Open Loop Fast Peak Detector

In this peak detector circuit, D1 is the detector diode and D2 is a level shifting or compensating diode. A load resistor RL is connected to – 5V and an identical bias resistor, RB, is used to bias the compensating diode. This equal value resistors RL and RB make sure that the diode drops are equal.

High values of RB and RL provide good low frequency accuracy but cause the amplifier to slew rate limit, resulting in poor high frequency accuracy. Low values of RB and RL (1k to 10k) yield in fast response, at the expense of poor low frequency accuracy. Adding a feedback capacitor CFB, which improve the negative slew rate on the (–) input, is the solution to improve high frequency accuracy. [http://www.hqew.net/circuit-diagram/Open-Loop-Fast-Peak-Detector_3405.html]

Single Chip FM Transmitter, For Short Range Application

The FM transmitter circuit here works in the broadcast band 88 to 108MHz, and can be used to broadcast audio signals for remote listening. The output power is around -21dBm, and the circuit operates with 3V power supply. Here is the schematic diagram of the circuit:

If you want to carry out your portable sound system around the house, this simple FM transmitter can be applied to links your mp3 player or your home-entertainment system. For example, if you want enjoy your favorites song in the backyard while doing barbecue, you can play your CD or MP3 player in your room and broadcast with this FM transmitter. All you need in the backyard is tuning your portable FM radio receiver to the music. [Source: http://www.hqew.net/circuit-diagram/Single-Chip-FM-Transmitter$2c-For-Short-Range-Application_3401.html]

Antenna Booster for FM, AM, and SW Receiver

This AM/FM antenna booster circuit amplify the broadband signal from antenna. This antenna booster should work fro FM, AM, and SW receivers. Here is the schematic diagram of the circuit:

Using this antenna booster circuit, for short wave reception, an 8″ antenna would produce a strong signal level equivalent to a 20 to 30 feet wire antenna. This antenna booster circuit is designed for general radio receiver, which its antenna is not tuned for specific frequency but for a wide band frequency. Try around 470uH for L1 coil for AM, and around 20uH for shortwave or FM frequency band. Use a standard 18″ telescoping type for this booster circuit. Bypass the supply to ground using 47nF capacitor? as close as possible to the L1 coil to prevent any noise picked up from the power cable. Install this booster circuit as close as possible to the antenna, shorter cables for better performance.

Source: http://www.hqew.net/circuit-diagram/Antenna-Booster-for-FM$2c-AM$2c-and-SW-Receiver_3397.html

Capacitance Meter Circuit

Capacitance meter is one instrument that you should have in your toolbox if you are an electronics hobbyist, or if you’re a professional electronic technician. If you can’t afford to buy such instrument or you you can’t find it on your local store then here is the good news: you can build your own capacitance meter. You can build a capacitance meter adapter to interface? between the capacitor to be measured and your general purpose voltmeter to read the capacitance value. Here is the schematic diagram of the circuit:

Just install a connector in place of voltmeter symbol, and now you can plug your analog or digital voltmeter to read the capacitance. If you use a digital one, then make sure if your digital voltmeter averages the signal reading with long time constant (over 1/10 second). Many low-cost digital voltmeter (DVM) usually is a dual slope integrator type that do the job. If your DVM is a fast sampling type then you should insert an RC filter, a 1k resistor and a 10uF electrolytic capacitor should be sufficient. More information about this circuit design can be found at [Source: http://www.hqew.net/circuit-diagram/Capacitance-Meter-Circuit_3380.html ]

Inductance Meter Adapter Circuit, Turns Your Digital Voltmeter to Inductance Meter

Measuring inductance is important in making your hand-made inductors, especially when you do-it-yourself (DIY) your coil winding. An inductance meter adapter circuit would be helpful since you can measure inductance using your general purpose digital voltmeter (DVM). This circuit cost much cheaper compared to already made inductance meter instrument. Here is the scehamtic diagram of the circuit:

The circuit is very simple, containing only one voltage regulator chip and one NAND gates chip. This inductance meter adapter provide two measurement range, low range for measuring 3uH to 500uH inductor values, and high range for 100uH to 5mH. Calibrating this inductance meter is easy. First you need to calibrate the zero offset. Connect your DVM to the output of this circuit, and select 200mV range for the DVM. Short the inductor measurement probe and adjust the sero calibration to give zero volt reading on your DVM. To calibrate the low range, pick a known inductor around 400uH. Select 2V range for your DVM. Measure the inductor and adjust the low-cal pot to give 1mV per uH inductance. For example if you use a 390uH then you should adjust the low calibration pot to give 390mV reading on your DVM. To calibrate the high range, switch the range of the adapter circuit to high, and use it to measure a known inductor with values around 5 mH. Calibrate the high-cal pot to give 100mV reading per 1 mH inductance. [Source: http://www.hqew.net/circuit-diagram/Inductance-Meter-Adapter-Circuit$2c-Turns-Your-Digital-Voltmeter-to-Inductance-Meter_3384.html]

5V Switching Regulator, Very Simple Circuit

Switching Regulator for High Power Efficiency

When you should regulate a high voltage to a much lower voltage, switching regulator must be the only choice. Fortunately, a simple switcher integrated circuit chip is available, let you build a complete step-down switching regulator using five components.

The switching regulator IC used in this circuit? is LM2575 series like we use in thye previous variable switching regulator, but we use the fixed type for the simplest design. LM2575-5.0 is a fixed 5V output switching regulator IC, capable of converting 7-40V DC to 5V DC at 77% efficiency. LM2575HV-5.0 can be use for higher input voltage up to 60V. This circuit is designed as step-down switching regulator, so the input must be few volts higher than the specified output voltage.

Source: http://www.hqew.net/circuit-diagram/5V-Switching-Regulator$2c-Very-Simple-Circuit_3390.html

Mini FM Transmitter Circuit

Here is miniFM transmittercircuit. TheFM transmittercircuit using 2 transistor. Audio sensitivity is very good when used with an ECM type microphone insert. This smallFM transmitteruses a hartley type oscillator. Normally the capacitor in the tank circuit would connect at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is. The FM transmitter coil is four turns of 18swg wire wound around a quarter inch former.

Here is a schematic mini FM transmitter:

Source: http://www.hqew.net/circuit-diagram/Mini-FM-Transmitter-Circuit_3354.html

Simple PreAmp MIC Circuit

Here is simplepreampmic. This circuits use infront an RF oscilator to make an RF transmitter that is very sensitive to sound. A microphonepreampmust provide stable gain for small signals without being sensitive to induced noise from cabling and without distorting large amplitude signals. A microphonepreampis a amplifier used to amplify a microphone's low output voltage to a stronger, more usable level. Most microphones must be used in conjunction with a microphone preamp to function properly.

Here is a schematic simple PreAmp mic drawing:

Read more at http://www.hqew.net/circuit-diagram/Simple-PreAmp-MIC-Circuit_3351.html

Simple Low Frequency Oscillator Circuit

Here islow frequency oscillatorcircuit. Thelow frequency oscillatorcircuit for testing tone controls and experimenting. The timing components, R1, R2, C1 and C3 dictate the oscillation frequency. In use preset RV1 is adjusted so that oscillation just begins. Thelow frequency oscillatorcircuit is a standard RC phase shift oscillator using a single bipolar transistor as the active element. When power is applied regenerative feedback is applied via C2 from collector to base of the transistor. Using R2 values higher than 1k or so may cause inaccuracy due to the attenuator loading. If desired, the output across RL can be attenuated. Here is a schematic low frequency oscillator circuit:

Simply replace RL with two resistors R1 and R2 according to the low frequency oscillator?table below:

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Variable Voltage lm723 power supply

Here is a variable voltage regulator using LM723 circuits. ThisLM723 power supply?have output on 1.3-12.2v 1A and over current protection. 2 sets the output voltage regulator. The maximum current is determined by the value of R3: the over-current protection circuitry inside theLM723 power supplysenses the voltage across R3 and starts shutting the output stage off as soon as this voltage approaches 0.65 V. C3 and C4, both ceramic, must be placed as close as possible to the integrated circuit, because theLM723 power supplycan be prone to unwanted oscillations. This way the current through R3 can never exceed 0.65/R3, even if the output is shorted.

Here is a schematic Variable Voltage lm723 power supply:

part LM723 power supply?:

B1 40V/2.5A
C1 2200uF (3300uF even better)
C2 4.7uF
C3 100nF
C4 1nF
C5 330nF
C6 100uF
D1 Green LED
D2 1N4003
F1 0.2A F
F2 2A M
IC1 LM723 (in a DIL14 plastic package)
R1 1k
R2 Pot. 5k
R3 0.56R/2W
R4 3.3k
R5 4.7k
S1 250V/1A
T1 2N3055 on a heatsink 5K/W
TR1 220V/17V/1.5

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Audio PreAmp MIC (dynamic) Circuit Diagram

Here is audiopreamp mic(dinamic). 200-600-ohm output impedance and low noise pre-amplifier for dynamic microphone is ideal for strengthening. This is a three-stage discrete amplifier with gain control. Alternatives such as the  BC109C  transistors, BC548 BC549, BC549C may be used with little change in performance. Thepreamp mic?circuit first stage is built around Q1 operates in common base configuration. It can not be used in the audio stage, but in this case allow Q1 to improve low-noise operation and the overall signal to noise ratio. Q2 and Q3 form a direct coupled amplifier, similar as with my previouspreamp mic. When the signal from a dynamic microphone is low, usually much less than 10mV, then there is too little to be gained by the collector voltage of Q1 voltage to half the supply voltage. Here is a schematic PreAmp MIC:

In power amplifiers, bias, half the supply voltage allows maximum voltage and maximum overload margin, but where the input is low, any value in the linear part of the operating system is quite nature. Here Q1 operating with the collector voltage of 2.4 V and a low collector current of about 200uA. This ensures a low collector current low noise and also increase the input impedance of the stage to about 400 ohms. This is a great addition to preamp mic any dynamic microphone with an impedance between 200 and 600 ohms.

source: http://www.hqew.net/circuit-diagram/Audio-PreAmp-MIC-%28dynamic%29-Circuit-Diagram_3346.html

Simple Variable Voltage Regulator Circuit with LM317 circuit

Here is a simple variablevoltage regulatorusing ic LM317 circuit. Thevoltage regulatoris an  LM317T,  and should accept up to about 14 volts without problems. It can handle up to 1 amp, but you WILL need a heatsink on thevoltage regulator. If you only plan to use items that run on one voltage, this is a very useful feature and will save plugging in and damaging your valuable (or not so valuable) equipment. You can even add a relay to switch off the power if the over voltage LED turns on, but bear in mind it will have to work from the voltage of the zener diode right up to the input voltage. The over voltage LED uses a zener diode to switch on the LED at a certain preset voltage, this can be varied depending on the voltage of the zener diode, I used a 6.2v zener diode.

Here is a schematic variable voltage regulator:

part of list variable voltage regulator circuit:

R1: 270R
R2: 2K Cermet or carbon preset potentiometer
C1: 100nF
C2: 1uF tantalum
LM317T Voltage regulator
Heatsink
PCB board

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Fluid level sensor circuit using common parts

A very simple fluid lever sensor can be designed using this circuit diagram . This fluid level sensor electronic circuit project is very simple and can be used to control water pump or to activate /stop some devices when the sensor detects presence of water.
This fluid level sensor circuit uses an ac sensing signal to eliminate electrolytic corrosion on the probes .The ac signal rectified is used to drive T1 transistor that drives a 12 volt relay , that can activate or stop some device . R2 resistor is used to modify the sensor sensitivity and can be replaced with a small variable resistor . MC104093B is a p channel quad 2 input NAND schmitt trigger and is pin to pin compatible with the CD4093. The unused inputs must be tied to an appropriate voltage level , either ground or 12 volts (8,9,12 and 13) and the unused outputs must be left open (10 and 11) .
The circuit can be powered with an input voltage between 3 and 18 volts dc , but in our case the circuit use a 12 volts DC power source .








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Door minder electronic project

This door minder electronic project uses an IR beam to monitor door & passage-ways or any other area. When the IR beam is broken a relay is tripped which can be used to sound a bell or alarm. This door minder electronic project is suitable for detecting customers entering a shop, cars coming up a driveway, etc. Because the IR beam is very strong distances over 25 yards can be monitored with electronic circuit . This circuit must be powered from a 12volt DC supply .
The transmitter circuit consists of two square-wave oscillators, one running at approx. 250Hz and the other running at 38kHz. The 38kHz frequency acts as a carrier wave and is required by the IR receiver module on the receiver board.
The oscillators are made by using two 555 timer ICs set up as astable configuration multivibrators.
Another 555 timer ( IC2) is used for the 38KHz oscillator. Resistors R4 and R5 and capacitor C3 set the frequency.
Diodes D1 and D3 are used to create a symmetrical output. Normally the external capacitor C1 (C3) charges through resistors R1 and R2 (R4 and R5) and discharges through R2 (R5). Without the diodes this output waveform would have a longer “high” time than the “low” time.
The output from the IC1 is coupled via diode D2 and resistor R3 to the trigger input of IC2. When the IC1 output is low it stops IC2 from running and IC2’s output is forced high (no IR LED current). When IC1 output is high, IC2 runs and the IR LED is pulsed at 38KHz.
The receiver module consists of an IR receiver module that detects the incoming beam from the transmitter. The IR signal is used to keep a capacitor charged which in turn holds a relay operated. When the beam is broken the capacitor discharges and the relay releases.









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Touch switch schematic electronic project

A touch switch sensor electronic project can be designed using this simple electronic diagram below. This touch switch sensor use one sense switch that allows shareholders "on / off". The capacitor C1 stores the switching state at the time. Depending on the signal output of gate N1, capacitor C1 is loaded or unloaded. On reaching the sensor, the signal is returned to the entrance of N1, so that switching state change occurs .

Circuit Diagram: 

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TDA0161 metal detector circuit diagram

Thesemetal detector circuit diagram is based on the TDA0161monolithic integrated circuit , designed for metallic body detection by detecting the variations in high frequency Eddy current losses. For detecting metals ,TDA0161  require an external LC tuned circuit .
Output signal is determined by supply current changes. Independent of supply voltage, this current is high or low according to the presence or the absence of a close metallic object. This metal detector circuit use two LEDs , which offer an visual indication of presence or absence at a metals ,around the coil . To adjust the circuit you need to make sure there is no metal near the coil and then set the fine adjustment to a "Mid position". After that you need to adjust the course adjustment to turn on the LED and , adjust the fine adjustment to turn off the LED.
This detector electronic circuit operates over a wide range input voltage of 4 -35 volts .? If you want you can use other values for the Cx capacitor and for L1 inductor? ( changing this value will affect the frequency oscillation and the detection range ) .








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Ion detector schematic circuit

An very simple ion detector circuit can be constructed like in the circuit shown bellow .As you can see in this schematic circuit this electronic ion detector circuit require few common electronic components .
This circuit detects static charges and free ions in the air .This ion detector circuit can be used for detecting presence of free ions , static electricity or high voltage leakage . Antenna used in this project is a short whip antenna and the R3 resistor is used to adjust the sensitivity of the circuit . The M1 from this circuit is an 100mA micro-Ampere-meter .
The ground connection is made by either an earth ground or can be attached to the hand using an aluminum foil .
The detector is set up to detect negative ions. It can be made to detect positive ions by simply reversing the polarity of the transistors that comprise the circuit, i.e., PNP units become NPN units, and NPN transistor is replaced by a PNP unit.
This detector circuit project must be powered from a 9 volts battery .








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Simple rain detector circuit

This rain detector electronic circuit project is an very simple alarm circuit , that will start an audio warning , if the liquid is present on the sense pad . This rain detector electronic circuit diagram is based on two transistors . When the sense pads conducts , Tr1 and Tr2 from an audio oscillatory circuit? that will generate a pitch sound .
This circuit needs a 12 volts power supply circuit and the speaker needs to have a 32 ohms . The sense pad can be constructed on a small piece of printed circuit board .








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Drilling machine speed regulator circuit diagram electronic project

Using this controller can be designed a speed controller regardless of the load. The electronic speed regulator can be used to control speed of drilling machine as the load grows, tcem Drilling of the machine decreases, while the current increases.
During positive half cycle of supply voltage, C2 is charged through R1 and D1 until the capacitor voltage is equal to the Zener voltage of the circuit to T1. T1 circuit is made with adjustable Zener voltage Zener is determined by adjusting P1.
The motor is not connected in the usual place at the beginning of the circuit, but after thiristor (SCR) Th1. Ignition time of SCR is thus determined by the difference between the Zener voltage and tcem of the motor. If the motor encounter a thiristor will "ignite" faster.

Circuit Diagram: 

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Detector de fulgere

In figura de mai jos este prezentat un detector de fulgere care este de de fapt un receiver construit pe o frecventa de 300KHz cu ajutorull caruia se poate sesiza descarcarile electrice produse in atmosfera.In momentul in care este detectat un fulger semnalul captat este amplificat ca apoi cu ajutorul acestuia un bec semnalizeaza prezenta descarcarilor electrice .

Lista de componente

Notatie	Valoare/Descriere
L1 L2 R1 R2 R3 R4 R5 R6 C1 C2,C3 C4 C8 C9 D1 Q1,Q3,Q4 Q2 R10(pot)	10mH 330uH 180k 3.9k 22k 2.2k 2.7k 47 ohmi 680pF 0.01uF 0.005uF 100uF 1uf 1N914 2N4401 2N4403 20k

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Miniemitator FM 4 ( max2606 )

Cu ajutorul miniemitatorului prezentat in figura urmatoare se poate realiza o "conexiune" intre un sistem audio si un aparata de radio portabil.Schema are ca element principal circuitul integratmax2606  care este un oscilator controlat in tensiune cu dioda varicap integrata.Frcventa de oscilatie este realizata cu ajutorul bobinei L1 de 390nH (in acest caz frecventa de oscilatie nominala fiind de 100mhz).Cu ajutorul potentiometrului R3 este posibila parcurgerea intregii benzi Fm 88...108Mhz.Cu ajutorul potentiometrului R7 se poate realiza reglerea semnalului audio ,acest lucru fiind necesar deoarece un semnal mai mare de 60mv poate produce distorsiuni. Montajul poate fi alimentat cu o tensiune cuprinsa intre 3 si 5v cc si are o putere de iesire de 21dBm pe o sarcina de 50 ohmi

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DC motor speed control circuit diagram using 555 timer

A very simple dc motor speed controller circuit can be designed using circuit that can be used to design a small drill project.
Q1, Q2 and U2 form a variable-frequency pulse width modulator, controlled by U3. Q4 forms part of a step-down power converter.
Speed regulation is accomplished by sensing the motor current with R17 and using it as positive feedback to compensate for motor resistance loss. The gain pot should be set to a point just below the point where the motor speed oscillates. After finding this point, you may want to change the value of R11 to get better speed control range.
Q3 limits motor current. D4 and C8 capture some of L1’s inductive kick to produce a loosely regulated -12 volts for U3. SCR1 acts like the usual flyback diode once C8 has stored the needed energy, preventing significant power losses.
This motor speed controller electronic project needs to be powered from a DC power supply from 12 volt up to 15 volt .
This speed regulator circuit is very simple an require common electronic components like 555 timer, operational amplifiers , transistors and passive components.








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A3952S DC servo motor controller circuit diagram

As we presented in another article the A3952S integrated circuit ( designed by Allegro MicroSystems ) can be used to design very simple and useful motor driver circuits .
In the precedent article was presented a simple bipolar stepper motor driver circuit that use two A3952S circuits.
As we presented in that article , the A3952S is capable of continuous output currents up to 2 A and operating voltages range up to 50 V.
Warning , the 50 operating voltage is to power the motor , for the logic controller you will need a 5 volts Dc power supply .
This circuit presents a simple DC servo motor application that can be used in various electronic projects . As you can see in the circuit schematic this Dc servo motor driver schematic circuit use just one integrated circuit and other few external electronic components .
With bidirectional dc servo motors, the PHASE terminal can be used for mechanical direction control. Similar to when braking the motor dynamically, abrupt changes in the direction of a rotating motor produce a current generated by the back EMF. The current generated will depend on the mode of operation.








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LMD18245 bipolar stepper motor controller circuit

Using the LMD18245 full-bridge power amplifier that incorporates all the circuit blocks required to drive and control current in a brushed type DC motor or one phase of a bipolar stepper motor can be designed various motor applications.
The LMD18245  controls the motor current via a fixed off-time chopper technique.
An all DMOS H-bridge power stage delivers continuous output currents up to 3A (6A peak) at supply voltages up to 55V.
The DMOS power switches feature low RDS(ON) for high efficiency, and a diode intrinsic to the DMOS body structure eliminates the discrete diodes typically required to clamp bipolar power stages.
An innovative current sensing method eliminates the power loss associated with a sense resistor in series with the motor.
A four-bit digital-to-analog converter (DAC) provides a digital path for controlling the motor current, and, by extension, simplifies implementation of full, half and microstep stepper motor drives .
This LMD18245 circuit application is a power stage of a chopper drive for bipolar stepper motors. The 20 kΩ resistor and 2.2 nF capacitor connected between RC and ground set
the off-time at about 48 μs, and the 20 kΩ resistor connected between CS OUT and ground sets the gain at about 200 mA per volt of the threshold for chopping. Digital signals control
the thresholds for chopping, the directions of the winding currents, and, by extension, the drive type (full step, half step, etc.). A μprocessor or μcontroller usually provides the digital control signals.
For this bipolar stepper motor driver electronic circuit you will need a 5 volt DC power supply for logic control and a 40 volt DC for powering driver .








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Cable tester electronic project

A cable tester device can be built using electronic diagram below.
Using electronic diagram below can test concomitant eight pairs of cable.
Electronic scheme is simple and consists of a clock generator (N1 ... N3) that control the 4-bit counter IC2. From all eight outputs of IC1, one is logical "0" during a certain period of tact. This signal then reaches trough inverters N5…N12 to clips cable connection. The other end of the cable is connected to the N13 .... N20 gates inputs. Among the outputs of these gates and the appropriate output of IC1 is located LEDs (D1 ... D16).
Odd-numbered LEDs (D1, D3, D5 ...) lights when output is in the state corresponding NAND logical "0" and while the corresponding output of IC1 is in state "1" logic. Even-numbered LEDs (D2, D4, D6 ...) lights only when NAND output is in state "1" logic and the corresponding output of IC1 is in state "0" logic.
If one cable is disrupted, the NAND gate output connected to it remains in state "0" logic, the two LEDs belonging to this output, diode corresponding odd number lights. At a correct binding, LEDs remain off, because when anode and cathode potentials oscillate at the same rate. Short-circuits between the cables are shown as in this case an even number LED anode is 1 and cathode is a "0" LED lights.
As long as no cable is not connected, the odd number LEDs lights.

Circuit Diagram: 

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Operational amplifier tester electronic project

Using this scheme can achieve an electronic tester for operational amplifiers. This tester allows a quick functional verification of operational amplifiers. For test this amplifier is connected as a simple square wave generator.
When S1 is pressed, the noninverting input of operational amplifier reaches a reference voltage which is the result of the output voltage divider R2/R3 voltage. Capacitor C1 is charged via R1 until the voltage at the inverting input is equal to the reference voltage. Since the operational amplifier working as a comparator, the output switch and reference voltage gets opposite polarity. Capacitor C1 charge properly again until the voltage reaches the reference voltage.
When operational amplifier output potential test is positive, T1 conducts and D1 LED lights, and if the operational amplifier is switched and output to a low potential, T2 conducts and D2 LED lights.
Transistor T1 may be BC107, BC547transistor type and T2 may be a BC177or BC557type.

Circuit Diagram: 

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Logic tester with acoustic indication electronic project

Using electronic scheme in the figure below can be constructed logic tester with acoustic indication. Acoustic tester in the figure below produces a low frequency sound when detects a logic 0, respective high-frequency sound when 1 logic is detected. The frequency produced by capacitors C1 and C2 depends. The input signal is supplied directly to the gate of N2 and reversed at the gate N3. If at input is detected, a logic gate N2 signal to pass through the amplifier A1. If a 0 is detected at input logic gate N3 signal to pass from the amplifier A2. The amplifier A4 form pulses from rectangular signal of the N4 gate which command transistors T1 and T2. With the buttons S1, S2 the oscillations can be turned on respective off. The circuit requires a continuous supply voltage between 5 and 10 volts and absorbs a maximum current of 10mA.

Circuit Diagram: 

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12 Exist Problems in The LED Lighting Industry

There are 12 exist problems in the led lighting industry.

1. LED color issues
Single LED applications basically does not exist the problem of chromatic aberration, but if a large number of LED to be put into use or a lamp with multiple LEDs, will highlight the problem of chromatic aberration to first say a group of lamps, if a glance the light of the inconsistent color, I want a happy mood they want to make a discount as LUXEON LED according to the color temperature is divided into eight military region, right in several residential and then in each Military Region, in a certain extent, a wide range of chromatic aberration control, but the same color area with a number of LED differences still exist, and this difference still can not run away to the naked eye provocation.

2. LED Insulation
(Insulation mentioned here refers to heat the substrate of the LED's positive and negative) would not say that we first discovered the insulation of the LED, but at least the big manufacturers questioned feel scared it is currently not resolved simply just take stop-gap measure, such as aluminum substrate to the insulation (the first aluminum plate did not do insulation, now almost all do) and we may think we can not understand. single LED is not insulated, has little effect on the series of many stars on a problem.

3. LED against pulse
This issue with the manufacturer remains controversial, in my actual application does exist, the main reaction in the cold pulse on power-on moment, the moment of a small number of LEDs in the cold state power breakdown or disconnect my opinion, is not static or high pressure due to (power voltage is within range)

4. LED light-emitting angle
Various manufacturers of LED lens package is not the same even if the same light angle (nominal angle), the effect is not the same, making the selection of poly mask difficult, to still not universal.

5. The hidden dangers of the potentially blinding LED
LED light points makes the center of brightness and super too concentrated, it is easy to hurt people's eyes, although some of the lighting manufacturers make efforts in this regard, but because of regulatory lag, only the moral problem of man.

6. LED heating problem
In theory, the LED is not very heat, but because of the immaturity of the current technology, the LED heat Yishi well known, I do not want to say.

7. The LED efficiency is low (luminous efficiency)
LED power conversion efficiency is too low (because there is no device to test, not giving specific figures).

8. The LED brightness is insufficient
Brightness is insufficient, making the current LED lighting industry can only play a supporting role, mainly used for decoration.

9. The LED light fades and life
Produced by the Mainland or Taiwan businessmen LED light  fades and life problems more serious, without further ado, the big-name vendors, such as the LUXEON nominal 100,000 hours, I am afraid only of their own psychological clearly, together with the thermal solution is good or bad, drive the matches are likely to affect the LED light decline and life expectancy 100,000 hours is just a selling point to!

10. The LED drive power
Most of the drive lines are borrowed from the switching power supply from the course, a very small number of lines is dedicated to the LED driver, but the effect is basically the same, due to the LED need DC drive, take the constant current control, the drive circuit is very large and can not compared with electronic transformer, and the efficiency is relatively low, reaching 80% to operator (single has not yet reached). In addition, firms in pursuit of applicability, the claim that a drive belt to ten random access (one, two , ..... all OK), in fact, this is a misunderstanding, although it is a constant current, high starting voltage will often LED to death in an instant.

11. LED modeling is limited
Makes the shape of the LED lamps LED single-sided light-emitting characteristics, subject to certain restrictions.

12. The LED unit price is too high
An import 1W-3W LED should be about three dollars, but also made more than 10 blocks (of poor quality, intellectual property rights) and about a 6 LED lamps sold to the hands of consumers, almost more than 1000 yuan RMB , Do you want to buy a color TV or buy a lamp.
Source: http://www.hqew.net/events/news-article/3582.html

Infrared beam barrier and a proximity detector circuit with IC 555

infrared detector circuit

Welcome again ,Free circuit dot com have the circuit can be used as an infrared beam barrier and a proximity detector.
The circuit uses the very popular Sharp IR module (Vishay module can also be used). NOS pin. circuit is shown in the Sharp and Panasonic modules. For other modules please refer to the relevant datasheets.
The receiver consists of a 555 timer IC  working as an oscillator at about 38Khz (also works from 36kHz to 40kHz), which must be configured using the standard 10K. The duty cycle of the IR beam is about 10%. This allows us to more current through the LED, allowing a greater range.
The receiver uses a sharp IR unit. If the IR beam from the transmitter IR drops, the output is activated, which activates the relay and turns off when the beam is blocked. The relay contacts can be used to turn ON / OFF alarm, lights etc. The 10K advance should be adjusted until the receiver detects the IR beam.
The circuit can also be used as a proximity sensor that objects in front of the device detects without obstructing a IR beam. So the LED has the same direction as the IR module and at the same level. The proposed scheme is shown in diagram. The LED should be adequately covered with a reflective material like glass or aluminum plates on the sides to stop the spread of the IR beam to prevent and get a sharp focus the beam.
When there is nothing for them, the IR beam reflected on the unit and therefore the circuit is not activated. When an object comes near the device, the infrared light from the LED reflected from the object on the unit and therefore the circuit is activated.
If there is still a very bad start, use a 1uF or higher capacitor instead of the 0.47uF.

Lamp Flasher Circuit with MOSFET IRF511

Lamp Flasher circuit with MOSFET

Welcome back to free circuit dot com,today we have circuit about control Lamp or call “Lamp Flasher” with MOSFET drive.
The working principle of this circuit is the MOSFET IRF511  and 2, the drive lamp turns on and off.
C1 and C2 with a speed controller works by receiving the voltage at the gate of the MOSFET when the voltage on C turn ON the other would be to drive MOSFET operation.
Source: http://www.hqew.net/circuit-diagram/Lamp-Flasher-Circuit-with-MOSFET-IRF511_3087.html

Infrared remote control tester circuit with Radio Shack 276-137

 

infrared remote tester circuit

Today,Free Circuit dot com would like to show you?used small infrared remote control tester circuit for controlling the operation of an infrared remote control.?
This is a fairly simple circuit for TV and VCR can be used to test remote controls. The infrared detector module (GP1U52X) (Radio Shack 276-137) provides a 5 volt TTL pulse train corresponding to the digital code to the button of the remote control. In the lower circuit, the module output normally low a signal and a positive going pulse train when a signal is present. Other detector modules that an inverted output is in the upper drawing, which showed type I, but I do not have the part number, I think from a video recorder.
The pulse sequence, the digital codes of special keys is available with information directly from the manufacturer. Since the pulse train occurs, the 4.7uF capacitor charges to approximately 3 volts and the capacitor voltage minus a diode drop appears above the 470-ohm resistor, a collector current of the 2N3904 or 2N3906 about 5 milliamperes. The collector current of the first stage flows into the base of the output transistor (2N3053  or MJE34), which provides about 250 mA in direction.
If the pulse train ends of the capacitor discharged slowly through the bottom of the first transistor stage left, the Christmas tree lights for about 1 second. The little Christmas lights will operate over a wide voltage range, so you can use bulbs from almost any string, but spheres of short strings (35 or less) will probably run longer at least 5 volts.
The circuit can be a small 9-12 volt DC, 250 mA wall transformer or operated higher. It can also be an additional 1000 uF capacitor filter on the DC output if the wall transformer no built-in capacitor. For use with a 9 volt battery, the light bulbs are replaced by a simple LED and 680 Ohm resistor and the output transistors by low signal transistor (2N3904 or 2N3906) can be replaced. The total power is about 25 mA with LED lights, standby and 15 mA when the LED should be.

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ADSL and DSL Inline Phone Filter Circuit

 

DSL Filter Circuit

When the ADSL and PSTN works on the same line at the same time, a problem the electronics in a normal telephone for high frequency signals ADSL: ADSL signals can be reduced (with high capacity intercom can be resonances in the phone, impedance mismatch ) and ADSL signals can be heard as the sound on some phones (electronic phone demodulates RF signal is out of range voting frequency noise). Just to keep these systems and stop interfering with each other, it is necessary for the two components of the telephone in your home to separate.
This is where the filter / splitter comes in. The ADSL POTS splitter / filter allows you to take full advantage of the frequency 1.1 MHz copper line to take, stopping the ADSL and phone systems interfere with each others.
An ADSL filter is normally a small plastic box with a short cable that connects to your telephone jack and two outputs, one for your ADSL modem and a telephone. Some filters have an exit by calling them. ADSL filter to the frequency band for each of the outlets, telephone or ADSL to select just the right tire and sending in the socket. The output of the phone is not receiving phone frequencies (from DC to 3.4 kHz) and the output is higher and ADSL freuquencies (above 25 kHz).
For good system performance, it is very important that all your other phone equipment is separated from the ADSL signals using a splitter / filter – This equipment includes telephones, answering machines, “normal” modems, etc., etc. .

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Increase current for IC regulator Circuit

 

Increase current for IC regulator circuit

Although the 78xx series of voltage regulators with different power outputs, you can compare the power generation by stimulating this circuitry. A power transistor is used to provide additional power to the load of the regulator, maintaining a constant voltage.
?Currents up to 650mA is flowing through the regulator, begins above this value and the power transistor to run, which provides additional power to the load. This must be a sufficient heat sink, because it is probably pretty hot.
Suppose you use a 12V regulator, 7812th Input must be a few volts higher to allow for voltage drops. Take 20 volts. Let us also assume that the load to draw 5A.
The power dissipation in the transistorVce * Ic or (20-12) * 8 = 40 Watt.
There you stay warm in the winter, but you will have a large heatsink with good thermal dissipation needs do. Do you want the output current with a negative regulator, such as increasing the 79xx series, then the circuit is similar, but a kind of power NPN transistor is used instead

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Simple Variable Frequency by 555

Here is a very simple circuit utilising a 555 timer IC  to generate square wave of frequency that can be adjusted by a potentiometer. With values given the frequency can be adjusted from a few Hz to several Khz. To get very low frequencies replace the 0.01uF capacitor with a higher value. The formula to calculate the frequency is given by: 1/f = 0.69 * C * ( R1 2*R2). The duty cycle is given by: % duty cycle = 100*(R1 R2)/(R1 2*R2). In order to ensure a 50% (approx.) duty ratio, R1 should be very small when compared to R2. But R1 should be no smaller than 1K. A good choice would be, R1 in kilohms and R2 in megaohms. You can then select C to fix the range of frequencies.

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USB Charger Battery Li-ON Circuit

here is usb charger circuit for you. this circuit used usb port to charge battery li-on. USB port capable of supplying a maximum voltage 5.25 V with a maximum flow of 0.5 A. Therefore, the above series can only be used to fill a Li-On Battery only. As LM3622 controller IC is used. IC’s main function is as decisive end and a battery charging. The LM3622 is a charge controller for Lithium-Ion batteries. This monolithic integrated circuit accurately controls an external pass transistor for precision Lithium-Ion battery charging. The LM3622  provides a constant voltage or constant current (CVCC) configuration that changes, as necessary, to optimally charge lithium-ion battery cells. Here is a schematic drawing:

Features IC lm3622
Versions for charging of 1 cell (4.1V or 4.2V) or 2 cells (8.2V or 8.4V)
Versions for coke or graphite anode
Precision (±30mV/cell) end-of-charge control
Wide input range: 4.5V-24V
Low battery drain leakage: 200nA
15 mA available to drive low cost PNP

Source: http://www.hqew.net/circuit-diagram/USB-Charger-Battery-Li$2dON-Circuit_3059.html

Simple vu Meter Analog Circuit

Here is vu meter analog circuit. The circuit is left connected to the line terminals of the amplifier. The VU meter is quite simple. T1 and T2 signal increase. The signal is then rectified by two diodes and fed to the meter. The capacitors C3 and C4 ensure that the voltage is slightly flattened and the meter responds less quickly. After building the circuit must be calibrated. To this end, the VU meter connected to a tone generator that delivers 0.3 V at 1000 Hz. Then P1 turned completely, ie the bishop of P1 lies at the entrance. P2 is then cut so that the meter is full deflection controls. Then P1 meter set to 0.5 mA (= half results) indicates. For a stereo VU meter circuit should be built twice.

part of list:

R1 = 1 MO
R2 = 820 O
R3 = 2,2 kO
P1, P2 = 100 kO
C1 = 330 nF
C2 = 22 μF
C3 = 1 μF
C4 = 470 μF
T1, T2 = BC 547B
M1 = meter 1 mA

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UHF TV Antenna Booster circuit diagram

This is thecircuit diagramof UHF band TV antenna booster with 15dB gain power. This low cost antenna booster is simple and easy to build.

This circuit formed based on BF180 UHF Transistor. The first stage is an band pass filter constructed by the C1, CV1, L1, L4, C7 and C3, the second stage is a base-common voltageamplifierwith low input impedance to match.air core coilconstruction and calculation here. After assembling, pack it into a proper metallic box and connect the ground of the circuit to the box to reducenoise effect.

 

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22W Power Amplifier with TDA1554 circuit diagram

Powered with main power IC TDA1554,  this circuit works up to 22W. A few externel components required to support the main component. Heatsink on the power IC is a must.

Components:

R1__________39K 1/4 Watt Resistor
C1,C2_______10uf 25V Electrolytic Capacitor
C3__________100uf 25V Electrolytic Capacitor
C4__________47uf 25V Electrolytic Capacitor
C5__________0.1uf 25V Ceramic Capacitor
C6__________2200uf 25V Electrolytic Capacitor
U1__________TDA1554 Two Channel Audio Amp Chip
MISC________Heatsink For U1, Binding Posts (For Output), RCA Jacks (For Input)

The? works best with 4 ohm speakers, but 8 ohm units will do. Thiscircuitdissipates roughly 28 watts of heat, so a good heatsink is necessary. The chip should run cool enough to touch with the proper heatsink installed.
Operated at 12 Volts and at about 5 Amps at full volume. Lower volumes use less current, and therefore produce less heat. Printed circuit board is preferred, but universal solder or perf board will do. Keep lead length short.
Download TDA1554 datasheet

 

15W FM RF Amplifier with 2SC2539 circuit diagram

This is a FM RF amplifier which build based on RF Power Transistor 2SC2539.
2SC2539 is a silicon NPN epitaxial planar type transistor designed for RFpower amplifiersin VHF band mobileradioapplications.
circuit diagram:

L1: 2T Coil diameter:4mm
L2: in series 6pcs Toroidal ring
L3: 4T Coil diameter:10mm
L1: 3T Coil diameter:10mm

FEATURES

• High power gain: Gpe >= 14.5 dB at Vcc=13.5V, Pout = 14W and f=175MHz
• Emitter ballasted construction and gold metallization for high reliability and good performances
• Low thermal resistance ceramic package with flange
• Ability of withstanding more than 20:1 load VSWR when operated at Vcc=15.2V, Pout=18W, f=175MHz, Tc=25⁰C

Download the datasheet of RF Power Transistor 2SC2539 HERE

 

1W Stereo Audio Amplifier with LM386N circuit diagram

This is a 1 watt per channel using two LM386N.  This circuit belongs to kitsrus.com and the kit is available there or at electronickits.com. This circuit only need 10mA current with best voltage supply is 6-12VDC. No heatsink required for normal usage.

There are only a few external components, the IC? contains most of the necessary circuitry. C1, C5 are? the input coupling capacitors, which block any DC? that might be present on the inputs. C2, C9 maintain? DC bias levels in the gain adjustment (feed back)? circuit. C4 provides power supply decoupling, and? C6, C8 are the output coupling capacitors. C10, R1? and C11, R2 act as zobel networks providing a high? frequency load to maintain stability where loud speaker inductive reactance may become excessive.? The pot provides adjustable input level attenuation.

Components :

Capacitors :
C1, C5 2.2 uF / 50Vecap _________2
C2, C9 10 uF / 25V ecap _________2
C3, C7 100 nF mono (104) ________2
C4 100 uF / 16V ecap ____________1
C6, C8 470 uF / 16V ecap ________2
C10, C11 47 nF mylar (473) ______2

Resistors :
R1, R2 10 ohm ___________________2
Pot 1 10k ohm stereo pot ________1

Misc. :
IC 1, 2 LM386N __________________2
8 pin IC socket _________________2

Download the complete explanation HERE

 

Basic Theory of DC to AC Inverters circuit diagram

This document entitled “The ABC’s of DC to AC Inverters”, arranged by Electronic’s Department of Northen Alberta Institure of Technology.

This document will show you the basic theory of DC to AC inverters, about the circuit’s works, the calculation to build DC to ACinverterand more. The sample of invertercircuit diagramalso included in this document.
Download theinverter document/paper here

Mini FM Transmitter circuit diagram

This is an mini fm transmitter. I think this is the simplest one. Simple, easy and of course…cheap… The supply voltage is between 1.1 – 3 Volts with power consumption is 1.8 mA at 1.5 Volts. This circuit should be able to cover 30 meters of range max. at 1.5 Volts.

Here the PCB Layout:

Visit this page for complete explanation.

 



 

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Hum Remover circuit diagram

“Hum” usually occured from liveaudiosystem, for example: input from microphone. Hum can be removed from an audio signal to get the maximum performance by mixing the actual hum with an antiphase hum in equal level. You can use any NPN transistor to support thiscircuit.
VR1 adjusted with VR2 until the hum is at minimum. SW1 may have to be changed over, then adjust VR2, is altered until the hum is removed.
Block diagram:

 

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100Watt Inverter 24VDC to 220VAC II circuit diagram

This is another 100watt inverter circuit diagram. Built based on IC CD4047  and Mosfet IRF540,  this inverter have ability to supply electronic device -which require 220VAC- up to 100w from 2-3A transformer..

 

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Portable Mic Pre-amp circuit diagram

This circuit consume low current supply (about 2mA), so will have a long battery life for supplying the circuit. The circuit built based on a low noise, high gain two stage PNP and NPN transistor amplifier, using DC negative feedback through R6 to stabilize the working conditions quite precisely.

12V DC Fluorescent Lamp Circuit

In this article I will offer driver circuit for 12 V/5Watt fluorescent lamp, this circuit used a normal 220 to 10V stepdown transformer in reverse to step 12V to about 240V to drive a lamp without the need to warm the filaments. Here is a schematic drawing :

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2 Way Crossover Active Circuit

This circuit is 2way crossover active, 18dB / octave unit, and has the crossover frequency centred on 300Hz. This circuit can be operated from the same power supply as the Audio Preamp, featured elsewhere on these pages. Other dual opamps may also be used, depending on your preference.Make sure that the power amplifier volume controls (if fitted) are turned fully up, and try to set the crossover controls so somewhere between midway and 75%. Here is a schematic drawing :

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Voltage Power Adapter for Car Power Supply

This voltage power adapter designed for car use only. And you know that a car voltage generally is 12 Volts. How about when you want to connect non 12 volts devices into your car?. The following power adapter circuit is the solution. Even the circuit is design for a car apppliance, it does not seem it can’t be used for another purpose. But you can try modifying it for any purposes. Here is a schematic car power adapter :

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Single Supply Phase Locked Loop

This circuit will function accurately over a 10:1 frequency range from 1 kHz to 10 kHz, but will not respond as quickly as the basic wide range phase locked loop (PLL). The reason is the use of the CD4046 frequency detector. When an FIN edge occurs ahead of a F feedback pulse, pin 13 of the CD4046  pulls up on C1 via R1 = 1 kW. This current cannot be controlled or manipulated over as wide a range as “I1” in basic wide range phase locked loop (PLL). As a consequence, the response of this PLL is never as smooth nor fast-settling as the basic PLL, but it is still better behaved than most F-to-V converters. Show a picture schematic :

Q1 = 2N3565 OR 2N3904 HIGH BETA NPN
A1, A2, A3 = 1/4 LM324
ON CD4046, PINS 1, 2, 4, 6, 7, 10, 11, 12 ARE NO CONNECTION
USE STABLE, LOW-T.C. PARTS FOR COMPONENTS MARKED*
VS = 7 TO 15 VDC

As with the basic PLL, the detector feeds a current to be integrated in C1 (and R2 provides the necessary “lead”). A1 acts simply as a buffer for the R1, C1 integrator. A3, optional, can provide a nicely filtered output. And A2 servos Q1, drawing a current out of C6 which is proportional to V2. Here the LM331 acts as a current-to-frequency converter, and F output is precisely proportional to the collector current of Q1. As with the basic circuit, this PLL can be used as a quick and/or quiet F-to-V converter, or as a frequency multiplier. One of the most important uses of an F-to-V is to demodulate the frequency of a V-to-F converter, which may be situated at a high common-mode voltage, isolated by photoisolators, or to recover a telemetered signal. An F-to-V converter of this sort can provide good bandwidth for demodulating such a signal.

Source circuit : hqew.net