The assembly of an audio amplifier is greatly simplified by using a ready-made module in it. To this you need to add a volume control, a decoupling capacitor, a power supply, and any suitable enclosure.
Instructions
Step 1
Purchase a board for a complete (preliminary and final) sound amplifier of the UM1-3 type on the radio market. In the past, they were installed in many color televisions. If you want to make a stereo amplifier, buy two of these modules. In addition to them, get a power supply with an output voltage from 7 to 12 V (stabilized or unstabilized) with a maximum output current of at least 200 mA, as well as oxide capacitors with a capacity of 1000 μF, designed for a voltage of at least 25 V, according to the number of amplifier channels. You will also need a single or dual (for a stereo amplifier) variable resistor of group B at 100 kilo ohms.
Step 2
Connect the power supply to the board (or two boards), but do not plug it in yet. Connect it plus to the module pin number 4, minus to pin 3.
Step 3
Take a variable resistor. Expand it with the leads down and the axis towards you. Connect the left pins of both sections to the sixth pins of both boards. Connect the middle terminal of one section to the second terminal of one board, the middle terminal of the other section - to the same terminal of the second board. Connect the right pins of the resistors to the stereo channel outputs of the signal source. Connect the junction point of the left terminals of the variable resistor sections to its common wire. In a mono amplifier, connect a single section variable resistor to one board in the same way.
Step 4
Take electrolytic capacitors. Solder the positive terminal of one of them to pin 5 of one of the boards. In a stereophonic device, perform the same operation for the second capacitor and the second board.
Step 5
Connect the speaker of one of the channels (with an impedance of at least 8 ohms) between the minus of the power supply and the minus of one of the capacitors. In a stereo amplifier, connect the second speaker in the same way, but to the second capacitor.
Step 6
Install the amplifier into the enclosure. Fasten all its nodes and parts. Turn on the signal source and amplifier power supply. Check if it works.
