Headphone amplifier with your hands in 15 minutes

Each novice radio amateur, after the first successful experiments, feeling the sweetness of his victories, wants to try to do something real. Not a toy, but a really working full-fledged thing. To do this, perfectly homemade simple headphone amplifier, which can be assembled with skillful handles in just a few minutes.

Where can it be applied? Firstly, for its intended purpose, namely to amplify the signal from a tonesblock or preamplifier, that is, where the audio signal is too weak and it is impossible to connect the headphones. In this case, you can make an amplifier for headphones with your own hands.

Secondly, it is useful as an additional tool. Portable headphone amplifier is perfectly suitable for testing circuits. After all, often there is a need to find the place of signal termination in the new circuit that you have assembled, but she does not want to work in any way. For example, you made the same headphone amplifier yourself. He will help in finding the cause of the malfunction. With it, you can very quickly find the point at which the signal disappears. After all, often this happens because of a trifle: badly missing parts, a faulty capacitor, etc. Visually or with a tester, the cause can be difficult to find.

Make an amplifier for headphones with your own hands simply, because the mono circuit consists of only five parts. It is based on the TDA7050 chip, which costs 30-80 rubles. But, I think that in your stocks of radio components, which are always available to anyone keen on this business, there is such a microcircuit. It was often used in cassette players and other simple devices that reproduce the sound.

On the same chip, you can make a stereo headphone amplifier yourself. To do this, you have to add two polar capacitors to the output (you can have one common), and the input volume control can be made from a dual variable resistor.

The chip itself is a power amplifier in a case of a normal size (DIP8). Operating supply voltage is from 1.6 to 6 volts. Consumes not a lot of energy. The output power depends on the supply voltage. In the stereo version with a load of 32 ohms and a voltage of three volts, you will get about 130 milliwatts output on each channel. When connected on a bridge circuit in the mono version, the power is doubled. The output of the chip is protected against short circuit.

The schematic diagram is given in Figure 1. The input signal is applied to pins 1 and 3, and headphones to 32 ohms are connected to pins 7 and 8. Under technical conditions in the bridge mode, the load should not be less than 32 Ohm. To smooth the voltage to the power bus, capacitors C1 and C2, 100 and 0.1 μF, respectively, are connected. The resistance of the resistor R1 is 22 kΩ. Well, perhaps, and all the description of our first model.

The second scheme from Figure 3 is often used in small-scale factory-made devices. To make it a little more difficult. The diagram shows all the necessary details. In Figure 2 - the same circuit for connecting the speakers. As you can see, the difference is small. In the circuit for the speakers, polar capacitors are used in each output channel, and for headphones there is a common capacitor in the place where the circuit casing is connected to them.