20 Watt Power Amplifier (IC)

There are many instances where a simple and reliable power amplifier is needed - rear and centre

channel speakers for surround-sound, beefing up the PC speakers, low powered tweeter amplifier, etc. For those who want to build their own 'Gainclone' amplifier, this will certainly do the job :-)

This project (unlike most of the others, but in a similar vein to Project 19) is based almost directly on the typical application circuit in the National Semiconductor specification sheet. You can also use the TDA3050 (from SGS-Thompson), which has almost identical performance and (remarkably) the same pinouts! As it turns out, the amp in the NS application circuit is pretty good, as is the (very similar) one from SGS. The amp is also remarkably simple to build - if you have a PCB! These ICs are a cow to wire on Veroboard - it is possible, but results are unpredictable.

From :: http://sound.westhost.com/project72.htm

16 watt amp

U1 U2	LM383 8 watt audio amplifier ic
R1, R3	220 ohm resistor
R2, R4	2.2 ohm resistor
R5	1 megohm resistor
R6	100k audio taper potentiometer
C1, C7	10uf electrolytic capacitor
C2, C5	470uf electrolytic capacitor
C3, C4, C6	0.2uf ceramic capacitor
SPKR1	4 to 8 ohm speaker (up to 8 inches diameter)

all resistors are 5 or 10 percent tolerance, 1/4-watt
all capacitors are 10 percent tolerance,
rated 35 volts or higher

this circuit provides 16 watts of amplification. it is built using two LM383 power audio amplifiers. use suitable heat sinks with the ic's.

50 Watt Amplifier

This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low pass filter at the input, it makes a great amp for a small subwoofer.

Part	Total Qty.	Description	Substitutions
R1	1	200 Ohm 1/4 W Resistor
R2	1	200K 1/4 W Resistor
R3	1	30K 1/4 W Resistor
R5	1	1K 1/4 W Resistor
R6	1	5K 1/4 W Resistor
R7,R10	2	1 Meg (5%) 1/2 W Resistor
R8,R9	2	0.4 Ohm 5 W Resistor
R11	1	10K Pot
R12,R13	2	51K 1/4 W Resistor
R14	1	47K 1/4 W Resistor
C1	1	100uF 35V Electrolytic Capacitor
C2	1	0.011uF Capacitor
C3	1	3750pF Capacitor
C4,C6	2	1000pF Capacitor
C5,C7,C8	3	0.001uF Capacitor
C9	1	50pF Capacitor
C10	1	0.3uF Capacitor
C11,C12	2	10,000uF 50V Electrolytic Capacitor
U1,U2	2	741 Op Amp
U3	1	ICL8063 Audio Amp Transister Driver thingy
Q1	1	2N3055 NPN Power Transistor
Q2	1	2N3791 PNP Power Transistor
BR1	1	250 V 6 Amp Bridge Rectifier
T1	1	50V Center Tapped 5 Amp Transformer
S1	1	SPST 3 Amp Switch
S2	1	DPDT Switch
F1	1	2 Amp Fuse
SPKR1	1	8 Ohm 50W Speaker
MISC	1	Case, Knobs, Line Cord, Binding Posts Or Phono Plugs (For Input And Output), Heatsinks For Q1 And Q2

From :: http://www.aaroncake.net/circuits/amp50w.htm

4-WATT AF AMPLIFER

The circuit is very simple and incorporates darlington output transistors that will provide more than enough output current than is needed to drive a 3-ohm speaker. The gain may be pre-set for a variety of input levels, making it suitable for amplifying computer and cassette-deck Line-output levels. The input level is also suitable for use with the TDA7000 receiver. All components are easily available and I will shortly be making this project available as a kit. Naturally, the project will be built on a PCB which will also be available separately. Here is the first PCB, assembled and working.

From :: http://web.telia.com/~u85920178/use/afamp-4w.htm

20 Watt Power Amplifier

This IC chip was designed specifically for use in power boosting applications in automobiles. It is self protecting against short circuits and thermal problems. In the bridge configuration shown it will deliver 20 watts of power into a 2 ohm speaker operating at 14.4 volts.

From :: http://home.maine.rr.com/randylinscott/may98.htm