[circuit] couple questions, should be easy!

jojor512

[H]ard|Gawd
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Jun 5, 2001
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I'm looking to build this circuit here, it's a simple 22 watt audio amp:
http://www.aaroncake.net/circuits/amp20w.htm

amp20w.gif

(diagram hosted from my site)

I understand the circuit for the most part, but any advice/knowledge on the following would be great!

1. Regarding inputs, how would I go about hooking up a single mini jack input? It wants RCA inputs. I know radioshack and the like carry those 1-2 adapters, but is one really necessary? I guess if I knew how they were wired i could make my own...

2. I like this circuit because it is so simple and because it is 12v. It pulls 5 amps at full power, and I'm curious as to how I would go about figuring out how long various batteries would last, or if I would be better off getting/making a power supply. If anyone knows any equations or any online resources in this area please let me know.
 
Rtstrider said:
on the 1-2 adapter do you mean like a Y adapter?

yes, I've used them to hook up my computer speakers to a TV that only has RCA inputs. I assume you can do the reverse. I guess I just need to know how to wire it, and how that would affect the sound, if at all.
 
If you are just connecting this to your computer, what I would do would be to get an old (or buy a cheap) set of headphones and cut the wires close to the actual speakers. Strip back both wires (be careful as there is an inner wire with an outer shield (ground). You could then connect red to right+ and (likely) white to left+. Connect both outer (shield) wires to gnd. That way you don't have to worry about any converters.

On this circuit. Am I the only one that is bothered by the fact that the 2nd input on those op-amps are left floating? I'd think they should be tied to ground or some kind of reference. Wouldn't they pick up interference or start to oscillate or something like that??
 
xtant3150 said:
On this circuit. Am I the only one that is bothered by the fact that the 2nd input on those op-amps are left floating? I'd think they should be tied to ground or some kind of reference. Wouldn't they pick up interference or start to oscillate or something like that??

I was too, until it dawned on me that they would use the pairs to get twice as much power out of it.
 
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