Can Anybody Identify This Circuit From These Pics?

Discussion in 'General Electronics Chat' started by Simmo, May 27, 2015.

  1. Simmo

    Thread Starter New Member

    May 27, 2015
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    Hey guys, I'm new here, I'll just get right to it...so I came across this at a place I volunteer at today and am curious as to what exactly it is, I'm sure it's an audio circuit of sorts with a 3.5mm jack and volume pot. I'm quite the amateur when it comes to electronics but I'm learning as best I can. I'd especially appreciate it if we could figure out what wires do what, though I'm pretty sure the white ones with the heat shrink on the end of it are the power leads, as for the rest...heck knows. Especially interested in the two quick release thingos. What I'm hoping is that this is a mini amplifier circuit of sorts that I could use to power a small speaker which would hopefully make the jack an input and not a headphone out, though I somehow doubt that. So what do the experts think? Here's the pics:

    [​IMG] [​IMG] [​IMG]

    Cheers guys I realize this may not be possible but any help at all would be greatly appreciated, thank you and any questions I can help you with don't hesitate to ask :)
     
  2. wmodavis

    Well-Known Member

    Oct 23, 2010
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  3. Dodgydave

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    Jun 22, 2012
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  4. Simmo

    Thread Starter New Member

    May 27, 2015
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    I feel a bit silly now but hey I got my answer! Didn't even think to google the letters on that...thingo. What are they called again? That little black thing with the TDA2822 written on it? Anyway thanks a lot wmodavis and Dodgydave, I'll be back with more questions as my learning progresses. Thanks again.
     
  5. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Here's my guess. The white pairs are the speaker wires, the black wires are the power, and the orange/white are the signal input. If you post a photo of the bottom of the PCB, that would help.
     
  6. Simmo

    Thread Starter New Member

    May 27, 2015
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    Underside as requested. I can't read schematics to save my life so those google links are confusing me but I'm looking into them nonetheless, they are helpful. How much voltage will I need to run this thing? 3 volts I'm guessing. Pretty sure the wires on the left here are the power supply lines. The white pair here on the right I think are the speaker wires, one of which needs re-soldering. Have no idea what the quick release leads do.



    [​IMG]
     
    Last edited: May 27, 2015
  7. Simmo

    Thread Starter New Member

    May 27, 2015
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    Update: Got it all figured out thanks in part to tracecom, the black wires are the power wires, the orange and white wires power a speaker and the white pair that I originally thought powered the board are actually signal input. The two white wires from the underneath well I have no idea what they do and everything works fine without them so I removed them. Something tells me they were a failed attempt at a mod anyway. Thanks all, this is really gonna come in handy for a project I'm working on.
     
  8. ian field

    Distinguished Member

    Oct 27, 2012
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    The twin screened leads suggest its stereo - there are appotes you can download that show how to use the 2822 in bridge tied load, you get a mono amp that produces 4x the output for the same Vcc and speaker impedance.
     
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  9. Simmo

    Thread Starter New Member

    May 27, 2015
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    Thanks for the info Ian. It is stereo and a powerful little driver too, hooked it up to a 9 volt last night and with a lot of fiddling held some wires to the input from a lead from my ipod and had the outputs to a pair of headphones, nice sound coming out of it, great bass. Really annoyed I seem to have lost a bunch of hobby boxes and other assorted bits and bobs I purchased last year so will have to buy a few more to start the bigger project which this circuit will be amplifying.
     
  10. ian field

    Distinguished Member

    Oct 27, 2012
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    I used to re-stock my junk box from the local tip, a lot of the electronic stuff still works but someone considered it old.

    When the tip was first taken out of local authority control and sold to a contractor, the bloke in charge was pretty much permanently drunk - you could often get away with good stuff for the loose change in your pocket. He hasn't been seen for a while and his missus has taken over the yard - last I heard, the only stuff going out of the yard is on the van to the auction.

    Last time I was there myself, the yard worker I used to buy my tobacco from had just been fired for nicking stuff out of the clothes recycling bin.

    I'll miss that place - once when the bloke was out, one of the yard workers let me have an AF function generator, RF genny and a digital counter, all I had on me at the time was £7 and some loose change. There was considerable emphasis on my making myself scarce before the bloke came back.

    If asked - I was to say I'd paid the money for a scrap bicycle to break for spares, so the boss probably got at least some of what I paid.
     
  11. Simmo

    Thread Starter New Member

    May 27, 2015
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    Haha nice score! I'm in an area where people like to leave their old electronics, of all places, on the side of the curb lol. It's how I got my flyback transformer which I want to build a ZVS for and get some arcs and sparks crackling. Got a LOT more to learn before I tackle that however. In fact that's just given me the idea to look into joining a local electronics club...
     
  12. ian field

    Distinguished Member

    Oct 27, 2012
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    If you want to make a Jackob's ladder - you can't beat a twin lead (wasted spark) motorcycle ignition coil, each end of the HT winding is brought out to a HT lead as the coil hangs between 2 of the plugs. One plug fires at the top of the compression stroke as you'd expect, the other plug fires while its valves are "on the rock".

    Most 4-cyl motorcycles have a couple of these coils, but only some twins have one of them.
     
  13. Simmo

    Thread Starter New Member

    May 27, 2015
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    A Jacob's ladder now THAT would be an awesome build!! Thanks for the advice I'll see about sourcing a coil :)
     
  14. ian field

    Distinguished Member

    Oct 27, 2012
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    Summer is just around the corner, so plenty of motorcycle shows/rallies with auto jumble stalls.

    Plenty of breakers yards specialise in dead motorcycles.
     
  15. cornishlad

    Member

    Jul 31, 2013
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    Only if you arrange to invert the phase of the signal through one of the amps channels.
    And only 2x the power is you stick to the power specs of the amp chips. The safe load impedance doubles in bridge mode so using the same (rated) load impedance and driving to 4x power risks serious clipping, overheating and possible damage..discuss :)
     
  16. ian field

    Distinguished Member

    Oct 27, 2012
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    The appnote that shows BTL examples also shows the method of inverting one signal path - there's various ways of doing it.

    I was going by the figures for older car radios - a half bridge push-pull with the usual 4 Ohm speaker can manage about 5W, a BTL version is just a little over 17W. When discussing such things with a typical petrol-head - that's as close to 4x as you need to be.
     
  17. Simmo

    Thread Starter New Member

    May 27, 2015
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    I'm in Australia, Summer's long gone haha :p

    Ian I was at my local electronics store the other day - in fact the very same day that I saw your post about the motorcycle coil - and a clerk there had built the same thing out of a coil that came out of a type of car that is very common over here. He had built it as a taser like device and had it mounted on the end of a staff as a halloween prop - they actually sell the entire circuit there as a jacobs ladder kit, all you need to supply is the ignition coil, it's very reasonably priced too so I'll be picking one up next week for sure.
     
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