Friday, 4 May 2012

Negative Voltage Inverter

I've done a few layouts using this method, but thought it may be useful to include a little daughter board which will allow you to easily convert any existing positive ground effects to (daisy chainable) negative ground.

Just de-solder the supply and ground wire from the existing board, and solder to this board, then take a couple of new wires from the -9V output and ground connections on this back to the de-soldered pads on the effects board.

5 minute job and you can get rid of your positive ground power supply.


104 comments:

  1. I have a feeling this will be VERY useful to me.

    Thanks.

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    Replies
    1. Yes I thought you'd be needing this soon which is why I did it! :o)

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  2. can you use a max1044 instead of the 7660?

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    1. You can. That's the equivalent of the ICL7660S because when you connect pins 1 and 8 to put it in boost mode, the oscillator frequency is higher than the audio range so you shouldn't get any squealing. If you've got some to hand then go for it, but if you need to buy them then I'd suggest going for the ICL7660S. My only issue is that the MAX1044 only rated for 10V which I think is too close to the 9V supply. Yes it will probably be ok, but not many people would use 10V capacitors if you could get higher rated equivalents cheaper.

      This is the last place I bought mine from:
      www.ebay.com/itm/250883870393

      So about £0.25 each for me, including postage.

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  3. Just wondering if this would work for a 18v centre positive pedal if the caps were rated over 18v? I have an eventide pedal that has to be on its own supply which is a real pain in the arse. I know gigrig sell one, but for £59 it seems a bit of a rort. And also can I put 2 input adaptors ie. 2.1mm style plugs in place of rewiring the internal power plug of my pedal so I can run it off a daisy chain psu

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    Replies
    1. Which Eventide pedal is 18V with a positive ground? You couldn't use this for anything above 12V anway (and I wouldn't even go that high) because that is all the IC can accept. There is an ICL7662 IC which could accept an 18V supply but it's obsolete.

      I just can't think which Eventide pedals has a positive ground, even if they have a positive centre pin.

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  4. Eventide time factor. I think all that range of "Factor" pedals are 18v centre pos. no biggy, just make it a bit tidier than having to have 2 power plugs, the one that comes with the eventide is a monster too, there's no way to conceal it either. I checked on gigrig and they make a reverse polarity adaptor especially for that range of eventide pedals but you have to buy the voltage doubler to take it upto 18v as well which ends up costing £118

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    Replies
    1. I've got a Pitchfactor and it has a 9VDC power supply? I don't know whether it's centre positive because I haven't checked the supply and have just been using the one supplied, but even if it is, it wouldn't have a positive ground.

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  5. Sorry mate, you are right. It is 9v. Don't know how I got 18v. Feel like a dickhead now. So this converter should work ok for the delay you reckon? Btw, what do you think of the pitch factor? Timefactor is probably one of the most versatile pedals I've ever had, kickass sound to boot. Just wondering what the rest of their gear is like

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    1. No because this is for converting positive ground pedals, like a Fuzz Face or Rangemaster with PNP transistors in them, so that they have a 0 volt ground which means they can be daisy chained in a conventional chain. The Eventide pedals will definitely have a negative ground, they've obviously just decided for whatever reason to use centre positive on the adapter, but that doesn't make it a positive ground effect. You should be able to use any standard DC adapter (as long as its capacity exceeds the 300mA needed by the Timefactor) and a polarity adapter like this:

      http://www.godlyke.com/power-all/power-all-cables/power-all-reverse-polarity-jumper-cord

      I've only recently got the Pitchfactor but I really like it. I've owned quite a lot of Eventide rack gear in the past and still have an Eclipse and DSP4000. I've always thought they were the best for (the obvious) pitch shifting but I also really love Eventide delay which adds nice colouration and fatness to the repeats. So I wanted something to use with a combo without having to mess around with a rack for a quick jam, and thought the Pitchfactor looked like a good choice because I can use it as a 2 second simple delay pedal as well (plus I love the crystals effect). So far I'm very happy with it.

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  6. That's excellent, thanks again mate. Is it the same thing just to chop an adaptor and just rewire it the opposite way?

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  7. quick question: would i be able to use a voltage sag knob, a la beavis devolt, on this if i took the DC jack to the 10k pot to the 9v+ strip on the left side of the converter?

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    Replies
    1. Yes. The IC will output the negative of whatever you put into it from 1.5V up to 12V max, so you could starve the input and it will perform the same function.

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  8. Just to clarify everything in the same row is connected? What are the red squares?

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    Replies
    1. The red squaares are cuts in the track that are used to isolate sections of the row so that everything ISN'T connected. Have a look at this build guide which should help explain:

      http://tagboardeffects.blogspot.com/2012/04/vero-build-guide.html

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    2. Will any of these chips at mouser suffice? I can't find the icl7660s:

      http://www.mouser.com/_/?Keyword=icl7660&FS=True

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    3. I don't know what all the designation variations are but none of the seem to be ICL7660"S" which means they don't have the boost function and so will squeal in an effect pedal. Have a look at the MAX1044, or you can definitely find ICL7660S on eBay.

      Delete
  9. Therr's anyone to convert from dc to ac?

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  10. Built this for a Fuzz Face which needed positive ground. Used the 7660S chip but it won't work, i gets REALLY hot tho. I dount i wired the board wrong, i mean it's so small so it's pretty much impossible to fail haha.
    nay idea what the issue might be?

    ReplyDelete
    Replies
    1. It getting really hot isn't a good sign. The current needed by a Fuzz Face can easily be supplied by the ICL7660S so that isn't the problem. Have you got another one you can test it with? I've used this method quite a lot of times now and so I know it works fine.

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    2. this happend to me too. and then I realized I WAS BUILDING ALL THE EFFECTS REVERSED! :) (as seen from the soldering side) simply bend the legs on the IC so that it faces the board with the side that says 7660S... and it wil work :)

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  11. Is the ICL7660S identical as the IC7660S you specify for the 9-18V doubler?

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    1. Yep. The "S" is always good to have there. I've used both circuits (doubler and -/+ pump) with ICL7660S. Actually ICL7660SCPAZ. Those are reasonable cheap to get from ebay. I remeber paying something like 3$ for ten of these.
      +m

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    2. Just noticed, but Doron is correct. It says IC7660 instead of ICL7660 on the IC at http://2.bp.blogspot.com/-yYGKBiFIRr8/Typ6JJ_JHoI/AAAAAAAAAhU/FSsSt8acW58/s1600/Charge+Pump.png

      I do believe that Mark meant ICL7660S there too...

      I was looking at something completely different and stubled on the datasheets of ICL7660 and ICL7660S. Normal 7660 can only take in maximum of 10V, but ones with that "S" are, as their datasheet puts it, Super Voltage Converters. They can take 12V in, but no more.

      I recently had one faulty power supply that put out 16V while it should have been giving out 12V. Sad thing for me, but after feeding one of those chips 16V, it still converts, but there is noise added. Even sadder, i didn't socket it as i was certain that it'll work..

      So i really had nothing important to say. Just felt like blabbering some.
      +m

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  12. Would your voltage converter work for powering the SCR. It needs a -9 and +9 lines. If I'm following things right I should be able to obviously get the -9 from the bottom row of your vero and shouldn't I be able to get the +9 from the top row on the boards right said as well?

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  13. i intend to try this for a stage center reverb circuit , the amp uses a single 12 volt sealed lead acid , ahhh , 8mah cell . thing is , fully charged these cells run like 12. to 13 volts ... hmm would this be ok ?

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    Replies
    1. If you use the ICL7660S, that can take 12V, but that's right at its limit, any more will likely damage the IC and so you're leaving yourself open to problems that may be cause by a quick spike. The ICL7662 can take 20V, but they are discontinued and more difficult to find. Also bear in mind these ICs are designed for very low current applications so the required current is important to consider.

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    2. Hmm. Wonder if placing 12V zener anode to ground and cathode to pin 1 could solve that. Maybe even placing 1N5817 as polarity protection (anode to supply, cathode to pin 1) before that. In my understanding that should make this fool proof to use with 12V - as with every other pump application of ICL7660S. Note that there has to be an S. S stands for super. Which stands for 12V max.
      +m

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    3. I actually had this exact same thought yesterday. Why not run something like a 7809 regulator in line with the +9v rail? That would keep the voltage hitting the ICL7660 constant.

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    4. Don't see any reason why that shouldn't work.
      +m

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  14. hi all, i've made one of this using a tc7660 cause i have i bunch of these....but i can hear a little the OSC frequency (near 10Khz),especially when the effect (PNP tone bender) is on, any suggestion to avoid this?
    thanks

    ReplyDelete
    Replies
    1. Yes, use the ICL7660S. The oscillator in the version without the S is at 10KHz and so often causes an audible whine. The S version runs at 35KHz with the boost function applied (no track cut between pins 1 and 8).

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  15. This comment has been removed by the author.

    ReplyDelete
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    1. Never mind, spent some time examining it and I don't think this is possible. Oh well.

      Delete
  16. how does everyone wire the battery snap in conjuction to dc jack using this method

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  17. not good..this gives noise to my pnp fuzz, oscilations

    if i take it out, there are no more oscilations

    and i did use the 7660S

    ReplyDelete
    Replies
    1. Could you have a tiny solder bridge somewhere in there? I've built something like 6 of these without any issues..
      +m

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    2. Yeah, but this NEVER happened, ever, before. I know you guys :D always say that to people. I'll build it again, but i'm sure it will do the same.

      Built a lot of stuff...Don't get me wrong, i always cut traces, check everything, 50 times, it WORKS, but with a certain fuzz, if i go past 4 o clock with the gain, the oscillations occur. If i take the inverter out they do not. So up till 4 o clock, everything is perfect. Worst case, i'll just leave it without the inverter and that's that.

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    3. I noticed extra noise with this voltage converter. I've added it to a mkI tone bender , and MkII tone benders and it adds a high pitched oscillation. Its not unusable but a little irritating.

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    4. Did you use an ICL7660S or ICL7660?

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    5. I'm not sure but I think I used the ICL7660. Is that one prone t noise? I didn't notice noise on one I made a few months back, which I could've used the ICL7660S in, but I don't remember.

      Delete
  18. Would a tc1044 work in this circuit?

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  19. Is this charge pump from Mammoth ok. It's a MAX1044CPA
    http://www.mammothelectronics.com/MAX1044CPA-Charge-Pump-by-Maxim-Integrated-Product-p/400-1125.htm

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  20. imi am also curious if a TC1044scpa will work as i have a few of these

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  21. Really nice blog!! I am glad to read your post, pretty informative..thanks for providing such a nice post.
    Inverter Manufacturer

    ReplyDelete
  22. I also got oscillation problems with this. I tried to counter that and burnt both of my chips in the process. Word of advice: do NOT put the chip the wrong away around, it will burn. In a blink of an eye :D

    ReplyDelete
    Replies
    1. Which chips you got? MAX1044? ICL7660? ICL7660S?

      I'd suggest to use a 9-10V zener to prevent the chip from getting too high voltage..
      +m

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  23. LMC7660IN here. Should work fine, right? The zener sounds like a good idea.

    ReplyDelete
    Replies
    1. There's your problem. That chip is rated for absolute maximum of 10.5V for the input. You should see if those work right with 8,9V or 9,1V zener (anode to ground and cathode to pin 1). That should fix it, as you wouldn't get anything higher than 9,1V going in, but the standard chips are known to cause oscillations.
      So.
      You should order some of those Super versions.

      Here are the datasheets:
      http://www.ti.com/lit/ds/symlink/lmc7660.pdf
      http://www.intersil.com/content/dam/Intersil/documents/fn31/fn3179.pdf

      Note that the ones with "S" after 7660 are rated for maximum of 12V for the input. That's what makes them Super. And that also means that it's safer and quiter to feed that with 9V supply. There are other differences too, but i've never had an oscillation with my Super chips :)

      Polida on ebay has them for cheap, but don't forget to ask for registered shipipng - it'll cost you $3 more, but you'll get the stuff in couple of weeks. The free shipping method takes months.
      +m

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  24. Hmm, actually did a little bit of research and it seems it might be the chip type. Gonna try and order other ones.

    ReplyDelete
    Replies
    1. Ha. You beat me to my answer... :)
      +m

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  25. Hi! I did two of this board (using ICL7660S) to power my Ge fuzz face clone.
    I use a Digitech power supply (form my Jamman solo)
    I wired the board between the DC jack (+9V) and the fuzz Vcc input (-9V).
    The DC jack ground is directly soldered to the input jack ground, as well as the daugher board ground. I soldered only one ground wire of this board, because all the ground from the main circuit are soldered on the input jack ground.
    The 1st IC "dead" when pluged the power supply. it delivers only -0.15V (my power supply delivers 9,6V). So tried the second board.
    The 2nd IC delivered -7.8V and died after 2 days.

    I used ELNA caps and ICL7660S from musikding.de. I never had any problem with them.

    That is why I am wondering if the wiring discribed above is OK. This IC seems to be fragile. Does it need a filter or something else?

    Thanks,

    Greg

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    Replies
    1. There's a filter on the -9V side, and you could add one if you wanted on the +9V side or even at the DC socket if you wanted to. But the IC won't die if it is unfiltered, it may be noisier but that won't destroy the IC. I've never had the issue you describe using this method, or voltage doubling. Are you sure it isn't a bad batch of ICs?

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    2. Thanks for your anwer Mark! Before thinking about these IC's were bad, I wanted to be sure of my wiring :)
      Do you agree that the ground to effect (on the right side) could be omited if I wire all the grounds (DC jack, daugher board and main board) to the ground of input jack ?

      I'll order new IC's and hope I'll be lucky!

      Thanks,

      Greg

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    3. Yes no problem. That was only put in there to simplify it in peoples minds in instances where it is used as a retrofit to an existing positive ground effect, and so emphasise that the daughterboard sits in between the supply and effect board. It's the same ground though so only needs one connection.

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    4. Thanks for your explanations Mark! I'll order new IC's and retry.

      Greg

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    5. Hi! I received my new IC's to retry this board, and this time it works! The negative voltage provided by the IC is the exact opposite of the supply voltage. Just had to retune my Fuzz Face. Next step : a Rangemaster - Naga Viper - Red Rooster mix!

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  26. Hi Guys!

    Do you know anything about MC34063API ?
    http://elinux.org/images/e/e6/MC34063A-D.pdf -> see page 8

    Dirt cheap ebay found 50pc/US $3.99 free shipping

    ReplyDelete
    Replies
    1. Well it certainly looks like it will do the job but the circuit won't be the same and I don't know how much money you'll save when you're going to have to buy components specially with the inductors and do a new layout for it. Personally I'd stick with these

      http://www.ebay.com/itm/261028247329

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    2. Yes, 7660S are my favorite to! Never failed on me. But I'll try to buy somewhere else. Every time I've bought from Polida, ended up with charging me for shipping or otherwise "the package may be lost". Well, for the last 4 orders I refused to pay more, now in the 3months+ waiting, and I think I'll never get those...
      Anyway, thanks a lot again for your advice!

      Delete
    3. It's a shame because the rest of the spec is fantastic. 100mA current, up to 40V and oscillator running between 24 and 48khz which is all great. Maybe they are worth looking into in more details to understand the way it works and what the external components are doing.

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    4. Yes, it does look interesting. I bet there might be a good use for it.

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    5. I've ordered some and found this calculator for working out the components required based on the input and required output voltage, plus current and ripple.

      http://sourceforge.net/projects/mc34063uc/

      and this online calculator:

      http://dics.voicecontrol.ro/tutorials/mc34063/

      I've got a set of inductors (which I haven't used for anything at all yet) :o) so I'll have a bit of a play with the circuit and see how accurate and stable the output is, and test it with an effect as a voltage doubler and inverter to see if it works well or if it introduces any noise or any other issue.

      I still think they're a pain compared to the usual charge pumps, but when you look at this and see you can get a 36V output from a 9V input with just a few component changes, then it may come in very handy for some other things in the future.

      I bought 50 because at only around £2.30 shipped I really wasn't going to save any money by just buying 10, so thanks for the heads up about this, I'll let you know how I get on with it.

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    6. Awesome! Yes that 36V pulled my interest to! Should be awesome for 9V input tube preamp.

      I'm really glad if I could help just a tiny bit, after all that I've learned here! ;-)

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    7. IvIark, any success with MC34063AP1? While I found a solution for ICL7660 with external 555 oscillator I still might run into issues with current (I have yet to build and test my circuit). I would prefer this solution to 230V and a transformer.

      Here's the info for oscillator:
      http://www.diystompboxes.com/smfforum/index.php?action=printpage;topic=24670.0
      http://web.archive.org/web/20081208131925/http://www.interq.or.jp/japan/se-inoue/e_ckt5_1.htm

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    8. I've literally only just received the ICs, hopefully I'll get chance to breadboard it this week

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    9. Did you get around to it yet? I'll have to try it because I'm getting distortion with 7660A :(

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    10. Haha, fun stuff. I burned a resistor (which I hoped won't happen) and blew a fuse in my DMM (not sure when and how).

      I can't comment on effects on audio but circuits next to it (connected to amp) were picking up some noise. I don't think I'm going to pursue this anymore, I would probably need to keep it on the other side of chassis and probably even shield it. I'm not even sure what went wrong and I still wasn't able to get any sound out of it because it stopped working correctly when I actually tried to use it (I'm trying to make single rail regulated supply into double rail).

      Delete
    11. This comment has been removed by the author.

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    12. I did wrong setup for inverter AND I have been inputing ripple in volts because other calculator had it in volts. I will have to give inverting setup another try again...

      http://www.bobtech.ro/tutoriale/componente-electronice/43-calculator-online-mc34063a-mc34063-step-down-step-up-inverter

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    13. I calculated a solution for inductors I have around and it finally works but I get significant drop with no load and huge drop with 470R load. No clue.

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    14. Sorry Adam I've had a lot of things on at home and haven't had a good opportunity to do any building at all, or even working on the breadboard for a while now. I'm even struggling to get some things posted out! I'll try to have a look over the next few days

      Delete
  27. Apologies Mark if I missed it in my thread reading but will ICL7660CPAZ ICL7660 CMOS VOLTAGE CONVERTER IC from Tayda work for me on this?

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  28. You want the ICL7660SCPAZ

    The S is the part you're looking for. This is the version designed for audio use

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  29. I can't see them at Tayda ebaystore.

    Here is my order just received yesterday, with surprisingly 4 days free shipping to Hungary.

    http://www.ebay.com/itm/301232134496

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    Replies
    1. Brilliant, thanks heaps Travis!

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    2. You're welcome! The ones RareDevil linked are the same brand I've been using with great results, though I bought them at mklec.com which is a great resource if you're in the US

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    3. Oh and apologies, thanks heaps RareDevil for the link :)

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    4. I'm looking at building a positive ground rangemaster and thought one of these might solve my power issues.

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    5. This is just awesome for that.

      http://tagboardeffects.blogspot.hu/2014/02/dallas-rangemaster-pnp-negative-ground.html

      Delete
  30. Built this one to use with my '69 clone. Worked great with a TC1044SCPA from Tayda. No extra noise, oscillations or crappy tone by any means.

    When I got back home tonight the pedal wasn't working anymore. I opened it up, took some readings... pins were not OK..., barely any reading on the trannies as well (all "0.0" but the Q2 collector, which was something like 0.2) and the IC was HOT! Got the voltage inverter off, back to battery, pedal is working fine.

    Anyone else had the same experience? This thing was great while it lasted.

    ReplyDelete
  31. Fried the 6th TC1044SCPA this morning. This is gettin' boring hehe. Some didn't last for a minute, others got some hours of playing time until they passed out. I'm using them with an One Spot rated at 9.4V so...not pushing them beyond the limits or anything like that. I had them fried while using them in daughterboards and in conjunction with a MKII PNP Bender (this one: http://tagboardeffects.blogspot.com.br/2012/03/tone-bender-mkii-pnp-with-negative.html).

    Think I'll order some ICL7660S and see what happens.

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  32. Used 1044 two times. Both failed. Never has problems with ICL7660S

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  34. How do I wire the jacks and the LED? Like a negative ground pedal or like a positive ground pedal?

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    1. Please see the last row. Ground is always ground, for jacks and for the LED to. It does not change. The power for the led from the +9V from supply (or battery) -> resistor -> LED+pole.

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    2. OK thanks.
      … and where does the input ring go to?

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    3. I think I got it. It has to go the power jack ground or to "minus" of the battery, doesn’t it?

      Delete
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  36. Hi guys,
    Mounted this before the full tone 69 fuzz clone posted elsewhere on this forum. But only get readings of
    -0.67v at effects end. 1-5 0.0,
    3-4 7.5v, 5-6 -0.67v and 7-8 0.0v.
    There are no visible solder bridges and the caps are placed according to the scheme. Can you guys please help? Desperate to find out if the 69fuzz works.

    ReplyDelete
  37. I found the solution thnx to Sumac. I bent the legs of the ICL7660 so that the little dimple faced to the plastic side of the board pins going through the board to the copper side. Now it works. Brilliant.
    Many thnx. I will send pics of my first build.

    ReplyDelete
  38. I realize this was originally posted long ago, but why is a 47u cap used for C2? The datasheets I find for this IC show 10u caps for both C1 & C2. I used a 47u in case this is biasing something to prevent "device latchup" without adding the optional diode or something else I don't really understand.

    Regardless of why C2 is the value it is, this layout works perfectly. I get -9.24V out to ground when using a 9.24V battery. I also get 18.48V when I measure +V to -V. This will work great for not only my positive ground pedals, but for low draw 18V pedals too. Many thanks!

    ReplyDelete
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  40. This comment has been removed by the author.

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  41. Something is wrong in your build then. Mine works just fine. Maybe you have the IC in the opposite direction?

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    Replies
    1. its probably the IC ..I am testing a maxx1044 in there now and its staying cool

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    2. i get so frustrated with all the fail builds ..I thinks its the IC maybe ..the maxx1044 seems to be working now ..although the first one with the 7660 worked okay at first 2

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    3. forgot to add in but the data sheets I am getting on google show both IC with a Vc max of 10 volts ..so I dont know how they are different ?

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    4. http://s33.postimg.org/51glzfrdr/Full_Size_Render_6.jpg

      so far, still cool ..hope it works

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