I designed a Win-driven by simple and practical power amplifier. Traditional Yun-driven amplifier, Yun-voltage due to the restrictions, the power to make. The amplifier used direct current voltage conversion of a drive amplifier power amplifier, the output power depends mainly on the upper stage of the amplifier and power amplifier, speakers and no on / off impact of sound. The whole plane did not increase any compensation capacitor, authentic, small phase-shift. As a result of operational amplifier for constant current amplification, so very different properties to facilitate the replacement of the operational amplifier, and sounds have more choices.
Circuit in Figure 1, IC1 and T1, IC2 and T2 were composed of current negative feedback absorption constant current source, are responsible for the audio signal is a half weeks and a half weeks of negative voltage, current conversion Larger, T3, T4 base only by the current IC1 , IC2 input voltage control, that is, as long as the Yun-enter as a constant pressure values of the upper stage of the T3, T4 collector current flow for a constant value. W1, W2 (multi-turn potentiometer) were used to adjust T3, T4 quiescent current and output 0.1, IC3 and R1, R2, R5-current composition of negative feedback circuit, as long as the corresponding changes in R3, R4 or R2, R6 resistance , Will be able to change the gain size.
The amplifier circuit protection (2) to cut off the power supply, power amplifier advantage is when a fault, not only to protect the speakers, while also protecting the end-of. Working principle is: When connected to power when, T6 in the conductance-, J aspiration for self-protection, power supply connected to maintain state.
When the DC component amplifier output greater than 0.1 ± 0.24V when, IC4 or IC5 a high-output, thus T5 on-saturated, T6 deadline for the release of the relay J, cut off the power supply, thus realizing the speakers and amplifier Of the protection.
Local debugging simpler, first W1, W2 transferred to the minimum position, and then slowly adjust W1, W2 to R8, R7 on the pressure drop to 40 mV (200mA). Measuring output, W1 or W2 to fine-tune the output voltage control point in the following 5 mV. Then preheat a half hour later, the tune again, you can access speakers attend an audition. Subjective evaluation, the amplifier signal to noise ratio high, bass fullness, flexible, thin smooth treble.
Yun-use NE5532 or AD827, and other dual-Wan Fang, T1, T2 check the power of 2 SB647, 2SD667, at the end of the optional power amp of the three is willing to 2 SC2922, 2SA1216 or 2 SC3281, 2SA1302, such as audio on the tube, with a resistance / 4W metal film resistors.
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