OT: Amp circuit

[John Bennett]

[ukvac] OT: Amp circuit
Hi all,

I'm trying to build an amp circuit using an LM380N IC which will take
a 12vdc input from a PC power supply. I know sweet Fanny Adams about
building circuits so I'll probably get it wrong anyway :-(

Thing is, I bought one of these 'Arcade Amp' jobbies from eBay and I'd
like to make another. It looks to be a simple circuit but I can't work
out about the big capacitor on there.

http://www.pcarcade.tv/grafx/Amp_circuit.jpg

It says 220u 16v on it - what's that in farads? Am I being daft? Don't
answer that.... ;-)

Any help in identifying the cap or an alternative suitable circuit
would be a _big_ plus.

I won't mention that this is for a MAME cab....



DATA Imported from archives: originally posted by Nigel Fletcher (njfletcher@btinternet.com)

 

[zepromz]

Re: [ukvac] OT: Amp circuit
At 18:18 21/09/2003 +0000, you wrote:
>http://www.pcarcade.tv/grafx/Amp_circuit.jpg
>It says 220u 16v on it - what's that in farads? Am I being daft? Don't
>answer that.... ;-)
>Any help in identifying the cap or an alternative suitable circuit
>would be a _big_ plus.

220u = 220uF (220 micro-Farads)
Thats just lazy typing by the guy who posted the spec.
Any old crap will do as long as the voltage is 16v or above, and the
value is between about 100 and 500 uF, o/p caps and smoother caps
on basic amp circuits like this are very unfussy about values, so as
long as the voltage is same or above original spec, then you can get
away with a lot of margin. 100uF, 220uF and 470uF are the common
values, you could substitute a 25v 470uF in the circuit with no ill effects.

 

[arcadeclinic]

RE: [ukvac] OT: Amp circuit
Hi Nigel,

It will be a 220uF (microfarad) capacitor. I expect it is used to feed the
speaker from the output pin of the LM380N.

Nigel

 

[John Bennett]

[ukvac] Re: OT: Amp circuit
It's also lazy typing by the Eastern person who printed on the cap. It
says '220u - 16V' which is why I asked about it. Not '220µF' as I
would expect. It's a reasonably large cap - about 18mm long.

Thanks for your help.



DATA Imported from archives: originally posted by Nigel Fletcher (njfletcher@btinternet.com)

 

[John Bennett]

[ukvac] Re: OT: Amp circuit
You're right - it appears to feed the speaker from pin 8 on the IC.

Many thanks.



DATA Imported from archives: originally posted by Nigel Fletcher (njfletcher@btinternet.com)

 

[Macro]

RE: [ukvac] Re: OT: Amp circuit
I always found the easiest way to build a amp for anything was to cut the
corner off of a bootleg mortal kombat or bootleg SF2 - they are nicely
isolated from the rest of the setup, and if you check the connections first
you are left with 4 wires to add - GND, 12V, audio in and speaker+ out - and
it conveniently has a volume control on it.