STEREO AMPLIFIER

The TDA2822M IC used in this project is a dual amplifier built into an eight pin chip. It consists of two channels, each identical and with external components to provide a very simple but powerful stereo amplifier, with a gain of 39dB and a current draw of 9mA with supply voltage in the range of 1.8 - 15 Volts. It will plug into the earphone socket of Walkman type machines and give excellent quality stereo sound from two speakers. Students are encouraged to research the fascinating technology of speaker box design.

With 55 mm 0.25 Watt Speakers

With 100 mm 2 Watt Speakers

Component	Description	Quantity
Resistor	4R7	2
Variable Resistor	10K	2
Electrolytic Capacitor	0.47uF	2
Electrolytic Capacitor	100uF	2
Electrolytic Capacitor	470uF	2
Electrolytic Capacitor	10uF	1
Ceramic Capacitor	0.1uF	2
IC	TDA 2822	1
IC Socket	8 Pin	1
Speakers	55mm Note: (100mm if requested)	2
Stereo Jack	3mm	1
Figure 8 Wire		1 m
3 Core Wire		0.5 m
Battery Holder	9V	1
PCB Pins		8
Solder		1 m
Slide Switch		1
PCB		1

Component Layout

Construction

1. To make up the Kit, firstly check the PC Board for any damage. Check continuity of all tracks with a multimeter or an electronic circuit tester.
2. The two resistors can be bent to shape and fitted, and the IC socket pushed into place. Solder them but be careful not to bridge across between the legs of the IC socket. The best way to solder is to heat the track beside the leg and apply a touch of solder. When the solder "takes" to the track add more solder and move the soldering iron to touch the leg. Build a small cone of solder making sure you have heated the leg enough for the solder to take.
3. The two 0.1 uF capacitors (104) are not polarised so they can go in any way round. All the other capacitors are electrolytic so you must observe the polarity of each. Look on the body for an arrow pointing down one leg. This leg is the Negative (K) leg of the capacitor. Check the drawing for correct polarity, and push them into place. Bend the legs to stop them from falling out and solder.
4. The two trimpots can be matched to their holes, pushed into place and soldered.
5. Pins are provided to terminate the input and output wires. Their holes are drilled larger. Push them in and solder.
6. Find the small + and - markings on the speaker and solder lengths of Fig.8 wire to them. The wire with the black trace is usually used for the +ve line. The -ve wires from the speakers should be joined and soldered to the circuit board pin in the earth rail of the PCBoard.
7. Connect the 3 Core wire to each of the input pins and ground (common) on the PC Board and the other ends to the two channel terminals of the stereo plug and common.
8. To fix the battery holder in place first melt a dob of solder to each leg up near the plastic, and also beside each of the two holes on the Board, but keep the holes clear. Push the holder into place, right down towards the Board. Use the tip of the soldering iron to fuse the solder together. There is also a switch to be connected across the +ve rail as the drawing shows. Solder both wires to the one side of the switch, centre and one end.
9. You will find that the legs of the IC are spread too wide to fit into the socket. Place the four legs on one side of the IC on the table and push gently so they are bent in slightly. Repeat for the other side. Find the locating DOT on the top surface of the IC, turn it so it is the way the drawing shows and push it into its socket.

Test your amplifier by plugging into the earphone socket of your radio or player, turn the volume down, and switch on. Adjust balance with the trimpots. Mostly you will find that the Amp will work first time.

MORE INFORMATION

View the Datasheet for the TDA 2822.

website:http://cdselectronics.com