Simple audio amp circuit?

scherzo · Post by **scherzo** » Thu Mar 23, 2006 9:47 am

Since I'm using the Hip Gear without its audio amp in my NESp, how do I construct a replacement that runs off of 5v for a single speaker? Can someone do a nice MS Paint drawing of one for me?

G-force · Post by **G-force** » Thu Mar 23, 2006 11:01 am

I made a mono audio amp that was only 1"x1"x.5". It runs off 3V-8V and is pretty loud. I'd prefer not to use MSpaint to draw it though. Is there a good circuit drawing program anybody can reccomend?

blackbox_dev · Post by **blackbox_dev** » Thu Mar 23, 2006 1:09 pm

ExpressPCB and ExpressSCH. Goto http://www.expresspcb.com Both a PCB design and schematic program, prices for manufactured PCBs are pretty good too.

timmeh87 · Post by **timmeh87** » Thu Mar 23, 2006 1:41 pm

or you could go for eagle, which is closer to being a professional tool

www.cadsoft.de

a lot of pcb manufacturers accept eagle files, so you arent always just limited to that one. this "express" software actually looks sort of like a ripoff of eagle.

Trv · Post by **Trv** » Thu Mar 23, 2006 8:23 pm

I made a simple amp.. here is the schematic. You can get all the parts at radio shack

http://www.national.com/ds/LM/LM386.pdf
look at gain of 20 on pg five. Note TWO pots are needed. The one in the schematic and ANOTHER right before the speakers. It took me two weeks to figure that out.

blackbox_dev · Post by **blackbox_dev** » Thu Mar 23, 2006 8:31 pm

Hey, sweet, I just found out eagle was free! I always thought it was one of those $900 kind of things.

scherzo · Post by **scherzo** » Thu Mar 23, 2006 8:58 pm

Trv wrote:I made a simple amp.. here is the schematic. You can get all the parts at radio shack

http://www.national.com/ds/LM/LM386.pdf
look at gain of 20 on pg five. Note TWO pots are needed. The one in the schematic and ANOTHER right before the speakers. It took me two weeks to figure that out.

Thanks. That's very handy. But why would it need two pots? Would both need to be adjustable externally?

EDIT: And, between Vs and Vin, which is the +5v and which is the sound signal?

A.J. Franzman · Post by **A.J. Franzman** » Thu Mar 23, 2006 11:19 pm

Trv wrote:I made a simple amp.. here is the schematic. You can get all the parts at radio shack

http://www.national.com/ds/LM/LM386.pdf
look at gain of 20 on pg five. Note TWO pots are needed. The one in the schematic and ANOTHER right before the speakers. It took me two weeks to figure that out.

And you figured it wrong, somehow. None of those schematics show more than one pot. If you built it right, it should work just fine with only one.

A.J. Franzman · Post by **A.J. Franzman** » Thu Mar 23, 2006 11:20 pm

scherzo wrote:between Vs and Vin, which is the +5v and which is the sound signal?

Vs almost always means Supply Voltage (in this case, +5V).
Vin is the audio signal that you want to amplify.

scherzo · Post by **scherzo** » Fri Mar 24, 2006 6:40 am

A.J. Franzman wrote:
scherzo wrote:between Vs and Vin, which is the +5v and which is the sound signal?
Vs almost always means Supply Voltage (in this case, +5V).
Vin is the audio signal that you want to amplify.

Thanks.

Trv · Post by **Trv** » Fri Mar 24, 2006 4:54 pm

A.J. Franzman wrote:
Trv wrote:I made a simple amp.. here is the schematic. You can get all the parts at radio shack

http://www.national.com/ds/LM/LM386.pdf
look at gain of 20 on pg five. Note TWO pots are needed. The one in the schematic and ANOTHER right before the speakers. It took me two weeks to figure that out.
And you figured it wrong, somehow. None of those schematics show more than one pot. If you built it right, it should work just fine with only one.

Well, i may have figured it out wrong. But if you have a problem when it is finished (you cannot adjust sound) add another pot like i said.

kalimot · Post by **kalimot** » Fri Mar 24, 2006 6:20 pm

i used a sega gamegear amp for my portable psone