LM1801 smoke detector circuit design electronic project

 

This smoke detector electronic project is designed using LM1801 and common electronic parts. Smoke detector circuit diagram below does not use ionization detection, gas or optocouplers it use two photoresistors (LDR's) and an LED.
Diode D1 rectifies voltage, R7 reducing voltage at a level suitable for integrated circuit.
The circuit uses a pair phototranzistors for compensation which removes any resistance caused by changes in temperature or aging effects. This circuit is made of network bridge R1, R4, two LDR's (R12, R13) connected to one of the comparator inputs common point of R4 and R13. The other comparator inputs are connected internally to the point of R1 and R2 voltage divider R12 and / R3. This arrangement provides both LDR's polarization to the same voltage, to achieve accurate tracking.
Physically, LDR s should be located so that smoke particles reflect light from the LED (D2) in R3, leading to lower its resistance. Once comparator detects this voltage drop, the integrated circuit commands Th1 triac (SCR) powering siren putting it into operating mode. Circuit sensitivity is adjusted with P1, the LED D2 should be mounted between the two photoresistors at approximately equal distances.

Circuit Diagram:

BH1417F FM stereo transmitter electronic project

Using BH1417F FM stereo transmitter IC can be designed a high efficiency FM stereo modulator electronic project .
This stereo FM stereo modulator circuit use the BH1417F FM stereo transmitter IC which consists of a stereo modulator for generating stereo composite signals and a FM transmitter for broadcasting a FM signal on the air. The stereo modulator generates a composite signal which consists of the MAIN, SUB, and pilot signal from a 38kHz oscillator.
This BH1417F stereo FM transmitter is capable of broadcasting good quality signals over a range of about 20 meters and is ideal for broadcasting music from a CD player or from any other signal source so that it can be picked up in another location.
This stereo micrometer broadcasts on the FM band (ie, 88-108MHz) so its signal can be received on any standard FM tuner or portable radio.

L1 coil comprises 2.5 turns of 0.5 - 1mm enamelled copper wire (ECW) wound onto a tapped coil former fitted with an F29 ferrite slug. Alternatively, you may also use any commercially made 2.5 turns variable coil.
The antenna for this micrometer circuit project consists of a 1.5m length of insulated hookup wire, with one end soldered to the antenna terminal.
S 1 , S2,S3,S4 switch is a SPDT subminiature switch (Jaycar ST-0300, Altronics S 1415 or equiv.) and is used for frequency selection .
Using the table below you can configure the transmitter frequency .

Circuit Diagram:

TDA7294 bridge power amplifier circuit diagram electronic project

tip42 Circuit  tl431c Circuit  lm1875t Circuit  AT24c512 Circuit  tda8177 Circuit

Using TDA7294 audio amplifier integrated circuit in bridge mode configuration , can be designed another Hi-Fi power amplifier .
In this TDA7294 bridge power amplifier the value of the load must not be lower than 8 Ohm for dissipation and current capability reasons.
The main advantages offered by TDA7294 bridge mode configuration are:
High power performances with limited supply voltage level, Considerably high output power even with high load values ( 16 Ohm).
The output power of this amplifier in bridge connection is 150 W with Rl= 8 Ohm , Vs = /-25V the and 170 W output power for Rl=16 Ohm, Vs = /-35V.

Circuit Diagram:

TBA810 audio amplifier electronic project

• Audio Circuits

The TBA810 audio amplifier electronic project can provide a 7 W output power on a 4 ohms or 2 ohms load impedance .
With a 4 ohms speaker TBA810 audio amplifier circuit needs to be powered from a power supply with output voltage of 16 V and if we using a 2 ohms load impedance the TBA810 circuit is require a 14.4 volts dc power supply .
This IC is class B amplifier with high efficiency and very low harmonic distortion .
The input voltage range accepted by this power amplifier circuit project is from 4 volts to 20 volts . Main features of this TBA monolithic power amplifier circuit diagram project are : low noise , few external components required , polarity inversion protection , high supply voltage rejection ( 40dB min.) .
This monolithic audio amplifier can be used in many audio applications for car radios ,other audio devices or portable applications .

Stereo balance indicator circuit design electronic project

• Various circuits design

This stereo balance indicator circuit diagram is designed using few common external components .The schematic circuit is very simple to build and will provide an visual indication with LEDs for left , right and center balance . Outputs from each channel are fed to the two inputs of IC1 connected as a differential amplifier . Output of the IC1 is connected to the noninverting inputs of the IC2 and IC3 . If the outputs of the IC1 approaches the supply rail , the outputs of the IC2 and IC3 will go high illuminating the LED 3 , this will show that the right channel is dominating . If the sound is balanced to the left channel , the Ic2 and IC3 will go low and the LED1 will light . If both channels are equal in amplitude the outputs of the IC2 and IC3 would be low and high respectively , lighting up LED2 .

Circuit Diagram:

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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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