Monday, 9 June 2014

Tiny Giant Amp

Requested by a few people on the forum, this is a mini amp circuit by Taylor Livingston with a bit more ooomph than the others on here, giving 20 watts into a 4 ohm speaker, or 12 watts into an 8 ohm.

Designed to run off a laptop power supply which I'm sure we all have hanging around the house from old broken laptops, with a LM338T taking that down to a regulated 11.6V to supply the opamp and amplifier.  The pins of the TDA7240A will need offsetting slightly so it is suitable for vero, but it can be done easily enough, as checked by Lazy Swamis on the forum.

Details of the project can be found here, and there is plenty of discussion to read through if you want to at diystompboxes.

Short clip of the amp in use






42 comments:

  1. Hi all.
    In a voltage doubler is a max1044scpa good to use in place of a 7660s anytime?
    dale

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    Replies
    1. The MAX1044 is rated for a maximum 10V supply, the ICL7660S can take up to 12V. Apart from that it would be fine, personally I prefer the peace of mind you get from the extra capacity from the ICL7660S, and they're also much cheaper.

      You can't use them in this though, it will be too much current for them.

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    2. I agree.
      Tayda here I come.
      jeff

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    3. Thanks.
      I am not building this one.
      I know, that to get your attention quickly, I go to the most recent post.....hee hee hee.
      jeff

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  2. Hi all ...Struggling to track down the TDA7240A. any alternatives? ...pref from farnell/cpc

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  3. any chance on a 9v power supply version?

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    Replies
    1. No, the amp needs a higher voltage

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    2. Could you use a charge pump before... maybe double the 9v to 18v then regulate down?

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    3. No the charge pump can't provide enough current

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    4. maybe a tripler charge pump, than go back to 20v.

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  4. Nice one! Ordered the parts for this this morning. I'm thinking of putting this into a small hi-fi enclosure, along with a Rump Roast and a Schaller trem. Can't wait to get building.

    I would urge EVERYONE building this to FULLY READ ALL THE DOCUMENTATION on the link above. That stuff about grounding and isolating the heat sinks is critical - you don't want to risk electrocution!

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    Replies
    1. How could a person Electrocute them self's at such a low voltage anyhow?















      Vince

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    2. I thought the danger was not electrocution, but rather burning up components. It's not all that much current really.
      Heat sinks probably never saved anyone from lightning poisoning.

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    3. Erm, sorry guys - Arse of the month award goes to me - (huge round of applause).

      That was really stupid of me. Swamis right, the bit about grounding relates to burning out your components, not electrocution.

      Must have been too tired last night. I'm going to sit in the stupid corner now...

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  5. got everything ordered or arrived. 1590A friendly for sure.
    I think I'll just zip tie the Tiny Giant on top of the reverb tank in my old vibrolux.
    The next time the old girl starts acting up in the middle of the show, I'll let her rest a bit.
    Thanks a heap lvlark!

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  6. Am I right in thinking I could put any preamp (is one of ROG's JFET emulations) before the volume control instead of the TL072 pre?

    If that's the case I think many people would enjoy a very layout for the post volume amp section only (which I assume is as per the TDA7240A data sheet?) to try some options out, tweak or create multiple pres monster mini amps *wink wink* :)

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  7. Hi!Can I replace LM338 by IP338 ?

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  8. Here is a mod to just use a 12v power supply, and get rid of the regulator. Could I just follow these same instructions when using your layout? Omit the 1K and 120R resistors, and connect the 2 legs of the regulator pads?

    http://i1160.photobucket.com/albums/q485/jdansti/0AB0651D-D4B0-46A7-A5F8-BDE5DD767627-12822-00000C36B2650DE0.jpg

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    Replies
    1. Good idea. 12 vc source is cheaper than the 19,5v
      Have made this in practice?? worked fine??

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  9. Anyone have any success building this yet? I'm still waiting on some parts from China. Should be here by next week hopefully.

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  10. I just got this all put together and am having trouble getting it working :-/ A few questions:

    1) What is the proper pinout of the amplifier? Numbering 1-7 isn't very informative, though I'm not entirely sure that's my problem.
    2) How am I supposed to connect the amplifier and regulator to a heatsink if they are sideways in the middle of the circuit?
    3) How are the speaker 1 and 2 supposed to be hooked up? To those correspond to - and + terminals of a speaker? Please clarify.
    4) Related: is speaker - allowed to be grounded? I would like to turn it into a 1/4" output so I can drive a cab with it like a head.
    5) Will someone please just take a picture of a completed build so I can double check mine? :-/

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    Replies
    1. 1) Pinout:

      1
      2
      3
      4
      5
      6
      7

      2) I used ribbon cable to form "flying leads" to do this.

      3) Yes, 1 to + and 2 to - (though it does not matter if you reverse them).

      4) NO - DO NOT GROUND the speaker jack. Use a plastic case jack socket or spacer sleeve to isolate to jack from the enclosure. (Read the PDF linked at the top of this page.)

      5) I will photograph my board when I've finished it, and put it on the forum post, (also linked at the top of this page).

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  11. Crud. I don't have any 2.2ohm resistors. Closest I have is 7.5ohm. How important are those values?

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  12. If you put 2 of those 7.5 ohm resistors together PARALLEL you would get 3.75 ohm which is a lot closer.

    Three 75.5 ohm resistors in PARALLEL would get you down to 2.5 ohm.

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    Replies
    1. That last sentence should read "7.5" not "75.5"

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    2. I've got a keyboard like that :o)

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  13. anyone get this one working? i was thinking that it would be awesome to put the preamp section for whatever amp you really want in front of this and you can essentially have a mini version. like putting an orange preamp in front could give you a mini 20watt orange that can fit in a guitar case.

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  14. I've got this layout working. A few words to the wise. .. . First, verify that your power supply can provide 4A or better. I neglected to check that and tried to make it work with a 2.6A supply and it just won't make any useful sounds that way. If you've got a big enough laptop supply laying around, you're in luck. If not, you're going to have to spend some money to power this thing. Next, you have to keep your signal wires away from your power wires away from your speaker wires, or you will experience a lot of noisy, crosstalky shit. Finally - get your heat sinks squared away before you start trying to power this up/troubleshoot it, lest you cook your ICs before you ever get it working.

    Thanks for the layout lvlark, so many fun projects. . . .

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    Replies
    1. how did you fit the heat sinks inside the layout ?
      i tried firing it up without the heat sinks...
      got kind of a floppy sound then a high pitch squeal ...
      the guitar sound is coming thru thowe with allot of distortion and low volume with allot of heat.

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    2. I could only fit a heat sink onto one of the two ICs in this layout without the heatsinks touching, so I wired the voltage regulator offboard.

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    3. Awesome, thanks for verifying Andy

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    4. ok so i installed the heat sinks and im still experiencing issues.
      im getting some floppy sound at about 60 hz frequency. it sounds similar to driving in a high speed with one of the windows in the back open.
      the guitar sounds very weak and distorted and still it goes to a high pitch squeal after a few seconds...
      you know what can explain this ?
      i'm running it thru a 3.17ohm 8 inch speaker.

      btw are there suitable sockets for ics like those in this project ?

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    5. https://dl.dropboxusercontent.com/u/35159092/20140809_173008.jpg
      https://www.dropbox.com/s/89q4nwu3s1ish67/20140809_173016.jpg
      i have provided with a few pics...
      can this problem be related to heat dissipation ?
      maybe my heat sinks our not sufficient ? i noticed that the ics our getting really hot while the metal boards i use are not heating up so much ?

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  15. I have a working layout that positions the 2 chips at one end of the board for heatsinking purposes. See here for details:
    http://www.diystompboxes.com/smfforum/index.php?topic=89687.msg983965#msg983965

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  16. Ugh. I started having problems with my build, cutting out plus intermittent if you nudged the power amp IC. During troubleshooting I broke one of the leads off the TDA7240 I got from China on ebay. I have since broken the leads on 2 more of them trying to replace it. I suspect I got some crappy ICs, they're barely rugged enough to install in a build. Be careful. Not sure where to look for better ones. Futurlec has them, not sure whether to expect theirs to be any different.

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  17. I'm doing something wrong here. Immediately after powering up the TDA7240 went up in smoke. I mean a TON of smoke.

    I did try to bypass the regulator and just use a 12v power supply. I read that to do this you can just omit the 1K and 120R resistors, and connect the I and O of the regulator? But that was for the PCB. Did I do something wrong doing with this vero layout?

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  18. Kinski - make sure you don't have something shorted to ground that's not supposed to be - like a wrong connection/solder bridge/missing cut at the board, or a metal bodied speaker jack connecting to ground, for example.

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  19. hey all,
    i apologize in advance for my english.
    i have built this little beauty for the second time now and still no success.
    the thing works in very very low volume. but when i try to turn the volume up a bit or sturm a few strings together i get this repeating pop sound.

    i build this with a slightly larger vero layout to accommodate the heat sinks.
    i have used monolithic capacitor for the 1u values.
    i tried looking for bridges mis matched components and such with no luck
    i replaced the amp chip the power regulator the ic and the power supply and got the same results with all of them.

    https://www.dropbox.com/sh/uq6n3x2f4u4z6t9/AAAk1LRsrtmeOfIAZZnpk2Ava?dl=0

    could it be one of the capacitors ?
    any ideas what could have gone wrong ?

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  20. Requested by a few people on the forum, this is a mini amp circuit by Taylor Livingston with a bit more ooomph than the others on here, giving ... mguitaramp.blogspot.com

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