LM317 audio amplifier

[HeavyMetal80sRules]

Can LM1875 works with 5 volts?

[techguytyler]

i know a great deal about amplifier and this circuit should work in fact i will build a amplifer around this videos diagram if you want to see it check out my channel

[Knzo911]

three seventeen..i love it..

[haz939]

be very cool if you could more LM317's in series to get more output!!

[JJRSJOAO]

Qual a potência de saída?  :)

[AmateurEngineer]

this Idea made me smile, thank you!

[madamerotten]

Why do you refer to the input and output capacitors as a "decoupling" capacitors?

[vegmatic1966]

@madamerotten They decouple (block) the DC from getting in or out of the circuit which would upset the proper operation.

[madamerotten]

@vegmatic1966 Then I'd say the proper description of their function is "blocking capacitors."

[vegmatic1966]

@madamerotten Checking the definition, decoupling is incorrect. They should be called coupling or more specifically, AC coupling capacitors. Decoupling or bypass is the cap from supply to ground in the circuit.

[madamerotten]

@vegmatic1966 I agree; "AC coupling capacitors" is the best name for them, since they couple the AC and block the DC.

[equipeturbilhao]

@madamerotten quantos rms tei esse amplificador

[madamerotten]

@equipeturbilhao I suppose close to 1W RMS, provided that the LM317 is sufficiently heatsinked and your loudspeaker impedance is low enough. Some of the power will be wasted in the 10 ohm resistor. You may be able to get more power if the 9V input is increased, but pay attention to the thermal limits of the regulator. Or try an LM1038, which is a 10A adjustable regulator.

[madamerotten]

@madamerotten Acho que perto de 1W RMS, desde que o LM317 é suficientemente heatsinked e sua impedância é baixa o suficiente. Parte do poder será desperdiçado no resistor de 10 ohms. Você pode ser capaz de obter mais poder se a entrada de 9V é aumentada, mas preste atenção para os limites térmicos do regulador. Ou tente um LM1038, que é um regulador de 10A ajustável.

[fabiode34]

Maybe someone already asked, but i can't find it.

How much current i need in my power supply? Where go the negative side of the power supply? I have 2 LM317 and i'm planning to build a stereo audio amplifier. Please reply to me ^^. Thanks in advice

[gushhnet]

Pretty neat current gain stage right there, I've known about this for a while (even joke about it to audiophiles just to annoy them) but never actually built one; I was going to resurrect some 317 projects I've had in standby for a while which is why I bought a bunch of them off of eBay and it turns out I got fakes, so that was quite a bummer. At least I got a refund...

[madamerotten]

@gushhnet Why risk buying these from a sketchy supplier on eBay when you can but the STMicro version (LM317T) directly from their authorized distributor, Avnet Express, for 24 cents each, or $20.31 per hundred?

[gushhnet]

@madamerotten Simply because I don't live in wonderland and shipping costs are ridiculous for me. Otherwise I can walk to the store and buy them -- if I'm willing to pay the extra markup that is.

[Flapjackbatter]

Neat. I have newer heard about this before.

You use the European symbol for resistors. Is this becoming more common in the USA ?

[vegmatic1966]

@Flapjackbatter Not sure if it is standard here, but it is cleaner to draw with my markers, so will start using it now.

[quantumbits]

Neat! never thunk it. thanks The cap and speaker are the AC load. The 10 Ohm resister is a dc and an ac load. So about half of the signal output is lost through the 10 ohm resistor. Is there a way to max that and transfer most of the AC through the speaker? i wunder.

[vegmatic1966]

@quantumbits A proper amp uses a second IC and support circuitry. I wanted to demonstrate a simple circuit others may try although not practical.

[quantumbits]

@vegmatic1966 Yep after reading a blog on the subject I am starting to understand that. Thanks again, i like your ideas.