erwin27
First Lieutenant   Posts: 6 Registered: 7/18/2006 Status: Offline
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posted on 7/18/2006 at 17:06 |
yea so i am attempting to construct a headphone amplifier, reallll simple
and basic circuit using the LM386 audio amplifier IC. but im not sure how
to connect the 1/4" input jack to the input of the LM386, ive tried wiring
it up, but it just ceases to work. Im almost positive the rest of the
circuit is correct. Whenever i measure the input voltage i get 0V and hence
i get no output, so it has to be a wiring problem with the input jack. Can
someone give me some tips/guidelines? thanks alot.
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brian
Moderator   Posts: 1075 Registered: 12/22/2003 Status: Offline |
posted on 7/18/2006 at 18:25, Reply 1 |
did you ground from the sleeve of the input jack? Are you building a clone
of another mini amp?
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brian
Moderator Posts: 1075 Registered: 12/22/2003 Status: Offline |
posted on 7/18/2006 at 18:40, Reply 2 |
I forgot to mention I had a similiar problem. I built a marshall guv'nor
clone the other day and got it all done and it didn't work.. I starting
messing with the board and heard it kick on and had no voltage on the
meter.. Come to find out I missed a resisitor to ground.. Now it works and
sounds better then the original.
Funny I didn't use a real board.. I cut up a clear cd sleeve printed the
layout on boxing tape then stuck it on the clear plastic sleeve.
This way I could solder point to point seeing both sides... I used a
drywall screw to neatly make the holes. hey it sounds great and I didn't
feel like etching aboard at the time.
Have you ever seen a see through board 
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brian
Moderator Posts: 1075 Registered: 12/22/2003 Status: Offline |
posted on 7/18/2006 at 18:46, Reply 3 |
here's a pic of the inside
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erwin27
First Lieutenant Posts: 6 Registered: 7/18/2006 Status: Offline |
posted on 7/18/2006 at 22:34, Reply 4 |
way thats reall cool what u did, very innovative!
im like now starting out with these guitar electronics stuff so im still
figuring stuff out. i havent done any etching or anything, still in the
prototyping stage using a solderless breadboard.
so i built the circuit on a breadboard, and no its not a clone, its just
the LM386 in its basic amplifier configuration which should be enough to
only drive headphones which is what im goin for.
and yea i did ground the sleeve of the input jack, so im really not sure
what im doin wrong...oh btw, im using a mono jack, should i be using
stereo?
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brian
Moderator Posts: 1075 Registered: 12/22/2003 Status: Offline |
posted on 7/18/2006 at 22:55, Reply 5 |
It could be anything and I can't say since I can't see it.. A mono jack
should be fine.
Double check to make sure all the ground points are grounded!
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erwin27
First Lieutenant Posts: 6 Registered: 7/18/2006 Status: Offline |
posted on 7/19/2006 at 03:11, Reply 6 |
hmm well i have a schematic that i would like to show you, but im not
entirely sure how i upload images here..
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Guitar101
Moderator  Posts: 481 Registered: 12/22/2003 Status: Offline |
posted on 7/19/2006 at 07:29, Reply 7 |
| send it as an attachment to contact@theguitarfiles.com we will post it! ____________________
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erwin27
First Lieutenant Posts: 6 Registered: 7/18/2006 Status: Offline |
posted on 7/19/2006 at 12:42, Reply 8 |
alright cool i sent it there.
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Guitar101
Moderator Posts: 481 Registered: 12/22/2003 Status: Offline |
posted on 7/19/2006 at 17:33, Reply 9 |
Here's the schematic you sent... The grey lines are all grounds! Make sure
all the grounds are connected together. Next make sure you have the opt amp
facing the correct way. Also make sure you have the positive side + of the
2 capacitors facing the correct way. I highlighted them in grey!
 ____________________
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