Tuesday, 5 January 2016

Switchable Onboard Power +9/+18V

Awhile ago I saw someone asking adding an +18V inverter to a board and the differences it made in some pedals, as well as what they need to do and worry about. Since there are more then a few people who have added an +18V inverter on a switch so they can switch between +9V and +18V, so I thought to myself, why not just whip up a quick layout to show how to do it for those that do not know.

Here's two that use an NE555 Chip



Here's two based on the 7660s/1044, based on the voltage doubler section of the madbean road rage voltage doubler section. schematic



Even though you can just run the +9V from the DC jack to SW1 and run that to the power in on the board, I don't like having multiple wires on a single lug of a switch so I made it so that you grab it form the board instead.

52 comments:

  1. I'm not sure if you intended this...but I noticed Pin 1 of the 7660S (the Boost pin) is grounded. Wouldn't you want to remove the cut between pins 1 and 8 (and the link to ground), connecting the boost pin to V+, to raise the oscillator frequency out of the audio band? It's set at 10kHz by default, so you would hear it.

    -Ryan

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    1. hey ryan. thanks for catching that. i was messing around with 2 layouts for two different IC's. it's been updated and i added the layout for the 7660s/1044 chip.

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  2. Hey Zach, thanks for the layouts. Is there any differences in performance between the two versions? I have not used the 555 version at all, so don't know myself.

    I'm thinking that with the relatively high price of 7660S and MAX1044 and the high chance of buying fakes if you find them cheap from China, the 555 version will be a cheaper and more reliable option.

    Do you know if there are any preferred versions of the 555, or any versions to avoid?

    Cheers,
    Mark.

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    1. not that i know of. the ne555 layout is identical to the one mark posted awhile ago and mentioned that it's cheaper alternative to the 7660s. the one thing though that i noticed between the two is that the physical size of the ne555 layout is just a little bigger and seems to use a few more components, so price wise it may just even itself out, but i'm not sure.

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    2. You can get more current from the NE555 version...

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    3. the difference between 555 and 7660s-1044 is as Zack said size and number of components.
      but there is an other difference between 555-7660s-1044-1054. Max Current...my great enemy those few weeks...

      http://www.madbeanpedals.com/projects/RoadRage/docs/RoadRage_2015.pdf

      i've read almost everything on this cause i wan't to make my rustbucket work, without paying 10 euros for just one 1054 chip...i need current!!!

      by the way i've build the 555 version Mark posted and it works just fine. though i didn't got 18v. i got something between 16v~17v

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    4. I've personally used this PCB layout I made for all my voltage doubling needs https://oshpark.com/shared_projects/PaTlnSoh . Made from one of Mark's 7660S voltage doublers on here. Using an LT1054, so pins 1 and 8 are not linked. The 1054 is $2.95 from Smallbear. The whole board works out to about $4 with components and PCB.

      And it's tiny!

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  3. You could do the switching with an SPDT on-on instead. 18V goes to lug 1, 9V goes to lug 3, and lug 2 goes to power the effect

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    1. That's how I have done mine too.

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    2. With the DPDT the Charge Pump is not consuming any power while being unused. That might be a benefit for some people...

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  4. Gracias, Gracias, Gracias, Gracias, Gracias, Gracias, Gracias, Gracias, Gracias!!!!!!

    555 rules

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  5. what are the difference between the version of "switch DPDT on-off-on" and "Switch SPDT on-on" i don't get it

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    1. not a whole lot, other then the switch and how it connects to this daughterboard and the main board. an SPDT switch is smaller and cheaper then a DPDT. and in reality looking at the DPDT switch it should be ON-NONE-ON, giving you either 9V or 18V, rather then having no power at all, so i'll make that change.

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    2. thanks Zach ;)
      here both switchs cost the same

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  6. why are there two ground lines?
    they are linked on the board.

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    1. correct. you only need 1 ground connection. the reason i put 2 is the idea that you can take the ground from the daughterboard and run it to the main board.

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    2. thaks for tellin
      btw, do you know any substitutes for the ICs?
      it is difficult to get them in Japan

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  7. The 555 is the highest selling IC ever made. It doesn't get more common

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  8. You can tag the 7660 version as VERIFIED!

    Puts out 17.68V from a 9.22V battery. I'm rebuilding my test box based on Miro's V2 and this makes a great addition. I've also built a simple 555 square wave oscillator that will act as a tone generator when debugging circuits (saves plugging in a guitar or my iPhone)

    Cheers man. Top job once again!

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    1. great job man. i was 99.999999% sure they would work, but since i didn't build it i had to wait for verification. it seems to me that you really never get 18v on the dot with a charge pump, but so what you got is spot on with what i normally see.

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  9. built it with 7660scpa. works great. gives surprising 19.5 V out of 9.5 V. might be slightly odd/bad voltmeter.

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  10. Argh, got a problem, maybe someone got a helping idea. when i try to use this fine thing for a 18v mxr m108 equalizer it is pulsing and my guitar makes scratchy pot noises. the later (scratchyness) i know as when there is current on a potentiometer. doesnt seem right. is this a common issue due to the oscillation and is there a way to avoid that?

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    1. it is pulsing only when i attach a guitar to the pedal. an open input cable without guitar is totally fine

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    2. something isn't right, and im not sure if it's the switchable power or not, but i think it's the mxr108 build. did it happen without it? what i mean is with 9V, rather then the voltage doubler. you might want to check the voltage of the doubler to see if it's a constant voltage or if it's fluctuating.

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  11. Thank you very much. tested the doubler. my dmm shows stable numbers. when i use it with a ep booster clone it sounds great. no issue, no crackling of pots.
    im afraid it is the pedal mxr.
    when i put a patch cable in input of the mxr its silent, no pulsing. seems alright. if i attach the guitar or short the patch( + to -) the pulsing starts and the leds blink ( what normally should indicate clipping on this pedal)...

    help very welcome

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  12. oh, and the mxr pulses the same manner with 9v batterie or wallwart.. seems to be pedal
    OR i damaged the pedal by pluggin in the doubler first time ( is that
    nevertheless the pedal works, but makes this pulsing sounds in the background

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    1. did you try different guitars or different guitar cables going from the guitar to the mxr? it could be either the mxr or the cables you're using connecting the guitar to the mxr.

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    2. I did sadly. Its the only thing left...

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  13. Hi. I just build NE555 circuit (the second one with the SPDT) for an EP boost circuit and I've been having some trouble. I blew up the 220uf cap on the top right twice (not sure why. They're rated at 50V). I tried reversing it so the white bit now faces down and the circuit seems to run ok (getting 16.7v) but now I've got a midrangey squeal through the amp that I wasn't getting without the charge pump. It's coming through with the switch in both positions.

    Does anyone have any idea on either of those issues? Blowing caps or the squeal? It's not heaps loud, and the boost still sounds quite good but it's too loud to be usable.

    Cheers

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  14. Isn't the 220uF between +18v and ground reversed in the NE555 versions??

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    1. hey man. just took a look, and yes they are backwards. thanks for the catch. fixed and reuploaded.

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  15. I got some tantulum 10u 35v lying around. Is it a got idea to use them for the 7660s?

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    1. Those will work just fine. Although i wouldn't do that myself. Tantalums are the best in signal path. For example, synth builders in my town go to lenghts avoiding tantalums in supply circuits due to their fear of tantalums shorting out in some cases. Never had a short with tantalums myself. But then again, i've only used those for signal path...
      +m

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    2. How about non polarised Electrolyte ones?

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    3. Should wotk fine. Standard polarized aluminun electrolytic will perform the best and be most reliable. Non-polar will work in the same manner, but cost more.
      +m

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  16. I just cannot get the 7660s version to work, I checked it multiple times and measured for shorts, but I get nowhere near 18V.

    1. I measured my adapter 9,45 V
    2. I connect it to the board and measure at the solderpoint of the 9V DC lug... 0,45V
    3. I measure at 18V output and get 0,33V

    I am going mad now.... Can anyone tip me what could possably be wrong?

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  17. Made a pcb of this to check what I could have done worng, but no difference. Maybe you can spot my mistake(s)?

    http://postimg.org/image/l8h1r51oh/

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  18. If you followed the layout exactly (great job on the PCB too) then this will work. If it doesn't work on both the layout AND the PCB, start removing the things they used in common....the IC, PSU, DC socket, reused caps?? etc. Eventually you will discover the problem.

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    1. Argh. When I remove D3 and no IC I get 9,45V but the 100u heats up. its a 35V rated one... Removing the 100u and placing the IC the IC heats up... When I replace D3 again, I get 0,45V again ... any hints? I have 100V rated 10u's.

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    2. Ok, ban me from this site :) I was so convinced it was not reversed polarity that it blinded me... what a noob error... sorry all for my questions. And you were right ciaran. At least I learned something again today! Do not be so convinced you checked everything before you really checked everything.. twice or more :)

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  19. Hi, what is the max. mA for these charge pumps?

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  20. Is it suitable for a ocd pedal?

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    1. No absolute maximum rating at the datasheet, but at least 40mA. Which is more than enough for 99% of the dirt circuits. Depends heavily on the load.
      http://www.intersil.com/content/dam/Intersil/documents/icl7/icl7660s-a.pdf

      And yes. With OCD and this, you'll get the EHX Glove. http://tagboardeffects.blogspot.fi/search?q=glove
      +m

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  21. It looks like the 220u cap at pin 3 of the NE555 is drawn reversed on both NE555 versions.

    I believe the negative leg of the 220u connects to pin 3 of IC NE555 and the + leg connects to the diodes jct.

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  22. I built the NE555 switch version for use with a Plexi Drive.

    I'm using a DPDT stomp switch for the switch and getting a pop when switching to 18vs. No pop when switching back to 9vs.

    I get the pop even without the LED hooked up.

    Any suggestions to stop this kind of pop?

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  23. Is it possible to have a 9volt to 6volt converter changing something in this layout?sorry for the stupid question,i'm new

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  24. You wouldn't need these layouts.
    Curious, why do you need 6v?

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  25. it's for a circuit bending project. So how i can do it?

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    1. I would probably consider switching in a higher current limiting resistor to drop the 3 volts. 1/2 watt resistor to be safe.

      I seem to recall JohnK once posting something about dropping 3 volts with a switch in a layout he had built. I'll see if I can find it.

      Can you post a link to the schematic or layout you are using?

      That will help suggest a proper way of doing it.

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    2. ok, I found John's post

      http://tagboardeffects.blogspot.com/2013/01/catalinbread-sagrado-poblano-picoso.html

      I believe John was referring to this voltage switching mod.
      http://www.muzique.com/news/mini-booster-fat-and-fatter/

      HOWEVER, THAT MOD WAS INTENDED TO BE APPLIED ALONG WITH AN APPROPRIATE CURRENT LIMITING RESISTOR. Otherwise the LED will burn out.

      Again, if you post the layout or schematic, I'm sure I can draw you a layout that would be appropriate for your pedal's design.

      Mike

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