Need Help with LM383 Amp design!!!!!!

[sir_modulus]

I have been trying to build a simple LM383 power AMP and wanted to know the answer to a simple question.

http://www.generalguitargadgets.com/v2/richardo/practiceamp/lm383.gif

in this schematic, what Wattage/ Voltage do the componenets have to be(specifically R1 and R2) and also, 2000 uf is not a standard value. 1000uf  is so two of them in parallel, or 2200 uf cap. What is better. Please help me as this is my first amp. THANKS

[petemoore]

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[spongebob]

I would assume standard ratings for resistors (1/4 watt) if not stated otherwise. The capacitor rating depends on the supply voltage, 16V should be fine, it doesn't hurt to take a higher rating, but caps get bigger the higher the voltage rating.

The 2000uF output capacitor does not have to be exactly 2000 uF, 2200 or something in the same area will do fine, I guess even 1000uF will probably be ok.

You might find interest in a similar project (which has an input buffer, volume and gain control, less output power though):
http://www.runoffgroove.com/ruby.html

[Mark Hammer]

Download the 383 datasheet first.  You can find copies in lots of places but here's one URL: http://www.eed.usv.ro/misc/mirrors/cc/dtasheet/LM383.PDF

The size of the output cap primarily determines low end frequency response.   if you are using this to power a 6" or 8" speaker for a small practice amp, I wouldn't worry that much about having flat frequency response down to 30hz or whatnot.  A 1000uf or maybe even 470uf cap will work just fine.

The chip, like so many, prefers to have what is called a Zobel network on the output, essentially a small value resistor (1R in this case) and a small to medium value cap (.22uf) in series to ground.  This is not essential but provides a little better performance from the circuit.

Also note that the chip will yield greater wattage output with a higher supply voltage and a lower impedance load.  So, 15v supply = more wattage than 12v, and 4ohm load = more wattage than 8ohm.  The 383 can take up to a 20v supply.  It is also essentially interchangeable with the TDA2003.