1. OCL Circuit
OCL circuit diagram shown in Figure 1, the circuit is a dual channel using two TDA7294 70W amplifier. External components, the circuit is simple, available in 8 ohm load when the supply voltage for the soil 35V 70W of continuous output power. Very suitable for the playback of the environment less than 30 square meters. Rectifier circuit shown in Figure 4, such as the speaker impedance is less than 8 ohms, the power supply voltage should be reduced accordingly.
2. BTL Circuit
BTL circuit shown in Figure 2, the rectifier circuit shown in Figure 4. Two TDA7294 bridge composed of the BTL amplifier circuit, the output power up to 150W, suitable for the place of the dance halls that require high-power, stereo, 4 TDA7294. Available on the 8-ohm load when the supply voltage for the soil 25V 150W of continuous output power. When the supply voltage of ± 35V, 16 ohm load, availability of continuous output power of 180W. With TDA7294 for BTL amplifier, the load shall not be less than 8 ohms.
3. Constant-current Amplifier
Constant-current amplifier circuit shown in Figure 3, the rectifier circuit shown in Figure 4. Of the amplifier circuit is somewhat different from the previous two structures, the feedback circuit for the current sampling voltage summation negative feedback. This circuit structure is commonly known as constant-current amplifier, the circuit analysis for detailed description is only the more prominent advantages compared with the conventional constant voltage amplifier.
①The amplifier output current and load impedance has nothing to do, even if the load short circuit, it will not cause the amplifier block overheating.
②Output power increases with the increase of the load impedance to drive the speaker load certain power reserve to ensure the bass of the original music signal strength and high-frequency resolving power.
③The role of the speaker voice coil force is only dependent on the current. Speaker driven flow control oscillation bound to be faster than the VCO, the speaker vibration system.
④Input and output impedance is easy to do matching. Constant-current amplifier circuit is actually a control input signal voltage controlled current source. Its internal feedback circuit for the current sample, the voltage sum of negative feedback, input and output impedance characteristics. High input impedance, just pre-constant voltage amplifier circuit, no loss of signal voltage to the amplifier input. The high output impedance, can reduce the internal resistance of the shunt on the signal, is conducive to the output signal current is added to the load. Figure 3, the supply voltage is selected as ± 35V, the magnification ratio of the decision by the speaker and R6.
TDA7294 Datasheet, download here
These datas come from http://www.hqew.net/circuit-diagram/Amplifier-Circuit-Diagram-Produced-by-TDA7294-_2315.html
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