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Portable 9V Headphone Amplifier Circuit Diagram
Description
Following numerous requests from correspondents, the decision to develop a 9V powered Headphone Amplifier was ultimately made. The primary requirement was to power the circuit using a common, PP3 (transistor radio) alkaline battery. Consequently, creating a circuit with a minimal current draw was absolutely essential, while still maintaining high-quality performance.
Circuit Diagram:
Parts:
- P1 = 22K
- R1 = 18K
- R2 = 68K
- R3 = 68K
- R4 = 68K
- R5 = 18K
- R6 = 68K
- C1 = 4.7uF-25v
- C2 = 4.7uF-25v
- C3 = 22pF
- C4 = 220uF-25v
- C5 = 220uF-25v
- C6 = 4.7uF-25v
- C7 = 22pF
- C8 = 220uF-25v
- J1 = 3.5mm Stereo Jack
- B1 = 9V Alkaline Battery
- IC1 = NE5532-34
- SW1 = SPST Toggle Switch
More:
- The introduction of the 5534 low-noise operational amplifier at an affordable price was greatly valued by audio designers. It is now challenging or impractical to design a discrete stage that matches the performance of the 5534 without significant complexity.
- 5534 operational amplifiers are now accessible from various sources, offered in a conventional 8-pin DIL format. This version includes internal compensation for gains of three or more, but necessitates a small external capacitor (5-15pF) for stability at unity gain. The 5532 represents a convenient package containing two 5534s within a single 8-pin device, with no spare pins.
- The 5534/2 is a low-distortion, low-noise device, capable of driving low-impedance loads to a full voltage swing while maintaining low distortion. Furthermore, it is fully output short-circuit protected. Therefore, this circuit was implemented using a single 5532 chip forming a pair of stereo, inverting amplifiers, providing an AC gain of approximately 3.5 and capable of delivering up to 3.6V peak-to-peak into a 32 Ohm load (corresponding to 50mW RMS) at less than 0.025% total harmonic distortion (1kHz & 10kHz).
IC1: NE5532-34
The NE5532-34 is a general-purpose operational amplifier widely utilized in audio applications due to its low noise, good linearity, and sufficient bandwidth. It is a three-terminal device with a differential input and a single-ended output. It is characterized by a low input bias current, which minimizes DC offset errors, and a high open-loop gain, enabling precise amplification. The 34 designation indicates it is a dual-supply version, allowing operation with both positive and negative voltage rails. It’s commonly found in audio amplifiers, instrumentation, and other applications requiring stable and accurate amplification.