Monday 30 April 2012

Boob Tube V1.5

There have been a few requests for tube based pedals and this is one I did previously.  Based around JuanSolo's 12V Boob Tube which is a Valvecaster variant, but here with a 33 - 40V supply via a charge pump.  Make sure you choose appropriate rated capacitors for the voltage.  This is verified and apparently sounds great.

Here's the tagboard layout:


And here's a charge pump, if you supply it with 12V you should get close to 40V from the 33V output point.  The ICL7660S can accept a 12V supply but that's the maximum for that IC, but you can't use the MAX1044 at 12V.


If you want to supply the charge pump with 9V and so avoid using a 12V adapter, you could use a 12V regulator off the 17V rail to provide the 12V required for the heater, or maybe even a voltage divider from the 25V rail.  In this instance you would only get around 33V for the plates though.

Here's the pedal built up and looking very nice, built by candletears7:



94 comments:

  1. What kind of effect is it?

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    1. It's based on the Valve Caster which is this:

      http://www.youtube.com/watch?v=3cMqYlhSQ8c

      But this has 12V on the heaters and 40V on the plates and apparently sounds much better.

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  2. Is there a way that I could connect the 3 power outputs to a pot & have variable power/starve pot kinda thingy, or will the circuit not allow for that?

    Definitely going to be giving this mofo a gogo! :0)

    Thanks dude, Matt

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    1. You'd only need to do it with the 33V connection, the other two voltages would be covered by the pot. And yes, it would probably be a worthwhile addition to get a bit of variety. Just take the 33V connection to a 10K linear lug 2 & 3 and lug 1 to the tagboard, like a bias pot on a Fuzz Face.

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  4. Smashing thanks Mark! Sounds awesome, nasty & dirty! I Like it ;0)

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  5. Could I sub the tube for a 12ax7, or is it a totally different current draw? I have one in here now & it works, it's just a tad quiet!

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  6. Bugger bugger, I'll grab one off the bay. Thanks matey! :0)

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    1. God it shows how they're all melting into one at the moment! I was thinking of another schematic that I've just been looking at with 6111 submini tubes in it which are the submini equivalent of the 12AU7.

      You could certainly try a 12AX7 with this, but you may find it's a bit too high gain.

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  7. Haha, is your head a little blagged mate? Sorry dude, but ya' just too damn good! ;0)

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  8. If I only need the 17v, then can I leave stuff out of the charge pump?

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  9. Yes, just build it like this:

    http://tagboardeffects.blogspot.com/2010/03/and-few-more.html

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  10. Do I need to start thinking about ways to dissipate the heat from the charge pump, or will it be ok mate?

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    1. No mate, just make sure the diodes and caps are rated appropriately

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  11. My build sounds pretty good as a clean boost, but I'm not getting much gain out of it. It looks like Milkit got good results, so I may have messed something up. Is it supposed to have more gain than an original 9/12v valvecaster? If not, what is the easiest way to increase the gain?

    Thanks and congrats on 200!

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    1. Have you got a 12AX7 you could try? Otherwise if you wanted similar gain to the Valvecaster you'd need to reduce the voltage. I haven't played with this circuit though so don't really have any recommendations on the effect of reduced voltage, so it may just be one you'd need to experiment with to get sounding how you like.

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    2. Good suggestion, I'll give some other tubes a try...just haven't had too much time to experiment. Thanks!

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  12. I finally finished this build *my first* and have found the overdrive/gain isn't very noticeable and sounds nothing like that valvecaster youtube video...I may try a 12au7 but what about switching the gain pot to a 250k or 500k? Would this increase the gain/overdrive?

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  13. I don't think this is supposed to be as "gainy" as the Valvecaster (I could of course be wrong), but it is a nice sounding effect, good break up! I tried a 12AX7 & that had more gain, but lacked volume in comparison to the 12AU7. If it helps, try this;

    http://www.youtube.com/watch?v=_j3vOL7VUc0

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    1. I was using my clapped out Marlin Slammer strat (which I love) & my SE-5A

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    2. I tried it again with my larger amp and fender strat and it sounded great! I also tried a 12AX7 and thought the 12AU7 sounded better...still curious about changing the pots though

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    3. Increasing the gain pot won't increase gain. It's not like an opamp circuit where the resistance of the gain pot determines how much gain you get from the IC, with this it just attenuates the level of the signal hitting pin 7 of the tube, the more you rotate clockwise, the less of the signal is dumped to ground and vice versa.

      At maximum gain clockwise rotation, it wouldn't matter if the pot was 100K or 500K or 100 ohms, the full signal will be reaching the second stage. Lugs 2 and 3 are then electrically connected and so none of the signal is being dumped to ground and the only affect a change there will have is on the cut off frequency of the high pass filter it creates with the 47n cap. If you use a lower value than 100K you'll start to cut more low frequencies.

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    4. Incidentally Matt, I somehow missed that vid when you posted it but just watched it and yes that's exactly how it's supposed to sound, great vid! I'll do a Valvecaster layout if someone wants it as well, but the point of the Boob Tube is that it is lower gain and doesn't get buzzy like the Valvecaster can.

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    5. Thanks Duder! Yeah I really like this one, it is as cool as cake man. I'm very tempted to marry this (as the 1st stage) with a noisy cricket & having a sweet little bench valve amp! I've had to get rid if SE-5A, bummer! ;0)

      I for one would certainly be interested in anymore layouts you may have with tubes good sir. I enjoy tinkering with these builds, but this one I enjoyed a bit more (possibly because of the tag board). Thanks Mark! ;0)

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    6. Thinking about it, you don't happen to have a layout or info at least on the zvex nano head do you mate? That would be a pretty awesome thing to build. ;0)

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  14. just uploaded a quick little demo vid of mine, www.youtube.com/watch?v=I9zBmnQITMk

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    1. Sounds really good.. I'd probs have a go at this but I'm not familiar with tagboard.

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    2. Get involved Vince, tag board is sweetola!

      Sounds great Johnny!

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    3. I may well do Milkit, I'll have a look into it ;o)

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    4. Thanks Johnny, that sounds really great, love how natural and fat it sounds. Personally I much prefer that to the Valvecaster demos I've heard, and with it being a pretty authentic tube preamp you can alway add a bit of extra dirt with the pedals of your choice to get into higher gain territory as well all do with our amps.

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    5. Thanks for your help with this along the way! In my research online I saw the twincaster and even a tricaster, one of these days I may have a go at those haha.

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    6. Vince, this was my first pedal build...EVER... and I am very pleased with it!

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  15. A friend asked me if one of these could be made for bass. I assume changing some caps would allow more bass signal in. Which caps would I need to change and do you think it would sound good or sound muddy?

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    1. It's a fairly low gain drive so I wouldn't expect it to be muddy. You could increase the input and output caps to let more bass through the effect, but other than that you have a filter created by the 47n and Gain pot which will start cutting bass at 32hz, so you may want to swap the 47n for a 100n to drop that frequency down to 16hz so you know the lowest notes shouldn't be affected. Same for the 47n at the Tone pot.

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  16. I have a dumb question that I think I already know the answer to. I got a 12vdc power supply that measures 17v on the multimeter [my other power supply measures exactly 12.6v] and I have read two different sides to this. Some say power supplies often differ in voltage and 17 shouldn't hurt, others say 17 on the tube heater will shorten the life and possibly overheat it....
    Do you think a 12vdc that measures 17v will harm the tube or the voltage pump?

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    1. In all honesty I don't know, I'm no expert in tube and amp theory. But you could always use a 12V zener between the supply and ground if you want to get closer to 12V out of it.

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  17. Finished my first tube anything ever.

    http://mirosol.kapsi.fi/varasto/boxes/TubeDrive_1.JPG

    Sounds soooo good. Warm preamp-like tone, that gets quite dirty when cranked up. There wasn't that much space in BB box for all this, so i fastened the board to the bottom lid. No-one's (hopefully) ever going to open it, so it's all good. Tried on couple of tubes, JJ ECC82 and JJ ECC83S. Latter gives some more dirt when compared to ECC82. Both are sounding excellent. This thing gives out so much soft volume that it's amazing.

    12V in (i recant my earlier statement - i used negative tip) and boy does it rock. This will be a keeper. I have second board unwired, but ready. I'm thinking about using it with JJ ECC82 as preamp for Ruby amp. I bet that combo will be crazy.

    Thanks again, big time!

    (P.S. any chance for original Ruby on vero? :))
    +m

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  18. so the charge pump layout doesnt show an output for 17v... how do you get the 12vdc tthe heaters require? i'm kinda confused here!

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    1. Two choices.

      I did this with 12V in, so i used first row to get 12V to the heater. 12V is also good, 'cause you'll get more out of the ICL7660S. I can recommend using 12V supply with this one though.

      Other option is to use a regulator (in from 17V, out comes 12V and last pin to ground). That isn't on the layout, so you'll have to figure it out...
      +m

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  19. I have a potentially stupid question: I've got both the Boob Tube and charge pump boards assembled, and I'm ready to test the circuits before I box the whole thing up. Having never used a charge pump before...does everything on both boards come back to a common ground?

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    1. Yes, all grounds shown on the board, and all offboard grounds like the input/output socket sleeves, DC adapter, pots and switch need connected together. Either at a single point (like the ground rail of the charge pump board) or daisy chained from one to the next.

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    2. Awesome, thanks. :) I really couldn't come up with any other way to do it, and it seemed correct, but I wanted to double check before I went too far forward. Hopefully I'll have a result to share sometime this weekend. Thanks again!

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  20. I've built two of these now, and log taper for tone may be worth while...
    +m

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  21. This comment has been removed by the author.

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  22. Wow, I totally missed this! Very cool!

    If you want a little more information about the some of the reasoning behind the effect, have a look here: http://juansolo.demon.co.uk/stompage/btbuild.html

    I knocked that together recently when someone asked me to so hopefully it explains things a lot better (and saves me a load of typing!).

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  23. It works best with a 12AU7A. It's the best balance of tone, gain and current draw we've found. The 12BH7 sounds pretty damned good, but make sure you've got a heatsink on your regulator if you go that way as it draws a lot more current and that puppy will get HOT.

    Be careful with unregulated voltages above also. The heaters either want 12v in series or 6v in parallel.

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  24. Also ideally you want to run the heaters from the supply rather than the pump. The plates draw very little current, but the heaters draw quite a lot. So regulate 9v to 6v, run at 12v straight from a regulated supply or regulate 12v from an 18v supply.

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    1. That's great, thanks for the additional info John

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  25. I tested the Boob Tube V1.5 with a 9Volt supply at both the heater and plate with a 12AY7 tube (I was Using the 12AU7A in a Matsumin Valve Caster) and to my surprise got a nice tone with a Reverb & Echo Pedal through a Noisy Cricket. It also sounded good with a 50W Fender Bassman.

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  26. If you used the v1.5 schematic, you'll not be giving the heaters enough voltage. Have a look at the link I posted above. You'll want to wire the heaters in parallel and feed them with a regulated 6v (look at the v2 schematic).

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    1. Ok Thanks. Will do. I actually was not expecting much with 9V to the heaters but it worked. The reason why I tried this is as the article stated ie. excess wiring in the pedal causes more noise that is irritating. I wanted to see how much the noise is reduced with a lower voltage. ie. Experimenting.

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  27. The heaters you want to run at their optimal voltages. The least we've run the plates at is 24v most 60v and the difference in headroom is noticeable.

    We've done them with all the components on vero with wire to the socket and it was significantly noisier than the ones where we've directly wired them. If you're going tagboard you want to do it like an amp with the socket as close to the tagboard as possible and the tone bits at the other side. It's probably the neatest way to do it by far.

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  28. OK Thanks. Next will be Boob Tube V2.0 Heater modification as per your link and a clean up of any excess wiring. Much appreciated.

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  29. Is pin 5 connected to the DC jack, or do the 12 volts go via the chargepump?

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    1. That charge pump wasn't done specifically for this, it was an older one which just shows a way to keep increasing the voltage with a charge pump. It says in the post "if you supply it with 12V you should get close to 40V from the 33V output point". So this is supposed to be supplied with 12V (no more because that is the maximum for the charge pump) at both pin 5 and the charge pump input. Then the final output of the charge pump goes to the tag specified on the board.

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  30. Dear IVIark, I stopped counting the number of pedals I made with your remarkable guidance and help! Do accept my sincere gratitude... please keep going, for the sake of all devoted DIY guitar maniacs worldwide ;) The Boob Tube is indeed a remarkable OD. I decided to challenge myself and fit it in a "B" enclosure, and, bingo, it worked.

    http://img543.imageshack.us/img543/9783/crikee.jpg

    Here is a very quick late night recording of the Boob Tube in a Tube Cricket... Very nice match, I would say. Way to go IVIark, once again, huge thanks Man !!

    https://soundcloud.com/darth_jabs/tube-cricket-and-boob-tube-od

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  31. Looking at the charge pump and this statement:

    "If you want to supply the charge pump with 9V and so avoid using a 12V adapter, you could use a 12V regulator off the 17V rail to provide the 12V required for the heater, or maybe even a voltage divider from the 25V rail. In this instance you would only get around 33V for the plates though."

    Does the charge pump have enough current for the entire board?

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  32. Great pedal! How can I increase clean headroom instead of gain, in order to use it like a clean preamp?
    thanks

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  33. Hi mate,
    please apologize my ignorance. I've been building pedals from your layouts for only 3 months. and I haven't built a charge pump yet.
    Why are there three voltage outs (17, 25, 33V)? which one have I to connect with my power supply? and how a 12v DC (for example) power supply could work with 17, 25 or 33V?

    It may be a obvious question for you, guys, but I get nowhere fast (which in french can be translated by "I'm PEDALLING in the semolina"... appropriate, isn't it?)

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    1. Use the 33V row, the others are shown just to give a little bit more information about the circuit, that other voltages are available if required. It increases the input voltage because that's what the IC is designed to do. It's a versatile chip which can give you voltage doubling or negative inversion (converting 9V to -9V for instance), and if you cascade the doubling as has been done here, the voltage continues to go up.

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    2. OK! thx!
      another question: you say pin5 of the tube is connected to 12Vdc. That's mean the pedal is going to have two dc jack? (one 9v for the charge pump, and one 12v for the tube)

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    3. I think you've already answered this question : "So this is supposed to be supplied with 12V (no more because that is the maximum for the charge pump) at both pin 5 and the charge pump input. Then the final output of the charge pump goes to the tag specified on the board."
      is it that?

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    4. No just use either 9V or 12V at both, whichever supply you're using. If you use 9V you may only get 30V at the output of the charge pump instead of 33V but that's fine.

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    5. I was ready to choose the 9v supply with a 78L12 regulator off the 17V, but I hesitate when you said that with 12v, "you'll get more out of the ICL7660S". What do you mean? the preamp will have more gain? the sound will be globally better? or is it a question of efficiency of the charge pump, with no relation to the amp?

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    6. At 12V input you will get a higher output. So where it says 17V, you may get 22V etc if you have a 12V input supply. But the ICL7660S is rated for 12V input maximum so personally I'd stick with 9V anyway to stay on the safe side for the IC.

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    7. ok! it's just as well, as 9v power supply is simpler to find...
      many thanks to you and your patience...

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    8. A 12V regulator from 17V strip and a a 12V zener from ground to pins 1&8 of the pump IC makes the supply pretty safe to use with anything from 7 to 12 volts. Heaters will get the correct 12V no matter what the supply is. And the 12V zener will dissipate everything higher than exactly 12V to protect the IC. It'll also act a polarity protection.
      +m

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    9. what do you mean by "from ground to pins1&8"? one side of the zener to the ground and the other side to both pin 1 & 8?

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    10. Anode to ground and cathode to the strip where there are IC pins 1 and 8.
      +m

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  34. Another question please. (I've already post it in the Ruby amp page)
    Mirosol built the boob tube and ruby amp together in a box. which pot do you remove? gain and vol of the amp, or the preamp's ones? and what modification in the layout(s)?
    I'm going to build it and I think 5 controls will be useless, or even problematic...
    thanks

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    1. I only omitted the Ruby's gain by replacing the gain pot with 220R resistor. There are Gain, Tone, Volume and Master Volume controls on that box. It's fun, but quite unusable after all.
      +m

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    2. thanks for the answer.
      I was thinking of a DIY audio solution for my workshop.

      Why do you say it's unusable? If you add a little cabinet (example 1 x 8") don't you have a complete compact guitar head and cab?

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  35. A question about the capacitors, when you say rated appropriately, which voltage do you mean? Thanks!

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    1. If and when you're running the circuit with ~40V it would be best to use caps rated at least 75V.
      +m

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  36. Hi,
    I've followed Miro instructions about 78L12 and 12V Zener.
    the voltage at the 17V output is 6.4 V (instead of 12V).
    Any idea about the problem, please?

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    1. anyone please?

      I don't understand why the voltages at the outputs are:
      17v = 6,54
      25v= 7,86
      33v= 8,16
      (input of the charge pump 8,38v)

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    2. They shouldn't and so you must have a problem with a component or your build somewhere. The charge pump board is so straightforward that I'm sure everything will be placed correctly which means you need to check your soldering, check for shorts and then if all else fails, start replacing components to see which one is faulty. We can give people ideas of what to check, but at the end of the day you just need to start swapping things to see if you can fix it.

      We know the basic layout works so I personally would take out the regulator and zener and see what voltages you're getting then.

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    3. thanks for answering me.
      actually I already checked a few things in the charge pump:
      place of the components, soldering, cuts.
      I changed the ICL7660,taken out the zener and the voltage doesn't change, and so do the regulator.
      I'm going to change the 1n5817's one by one, and the 10uf also.
      it's very annoying to have everything ready, tube, pcb.... and this charge pump which don't want to run... :-((
      however thanks for all.

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    4. Hi,

      Mine has considerably more gain with a TAD 12AX7 compared to a JJ 12AU7. Also, with 12,3 V going into the charge pump I am getting 48,1 Volt from the 33 Volt connection on the charge pump. When I put in 9,3 Volt I am getting 36,5 Volt from that connection.

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  37. Damn I'd love to build this but how big (diameter) is the hole for the tube? I think the most my drill can do is 12/13mm

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    1. Depends on the tube socket (you can't fasten the tube by itself). Those come usually for 18mm or 20mm holes. I'd suggest getting stepper drill bit. Those are great for stomp switch and dc jack holes too.
      +m

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  38. Just built mine.... good boost.
    Two things I did different.
    1) I used a Schmitt trigger 40106 to power the board. Using a 12 volt power supply and "de-hummer" circuit, I wound up with 67 volts going to the board. The Schmitt trigger circuit will boost a voltage supply up to 6.66 times its original strength. I should of got close to 80 volts, but the "de-hummer" circuit drop the voltage about around 2 volts.

    2) With the higher voltage I could use a 12ay7 tube. Which provides more gain.

    I find this project best with a overdrive pedal (something like a tube screamer) in front of it pushing it hard.

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  39. I have a little problem, when i solder on pin5 to heat, my ICL7660S is starting to warm up. Without tube are the right voltage on all pins. The resistance between pin 4 and pin 5 is just 13 ohm (not kilo ohm) is it normal? can my tube be wrong?

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    1. I have the same problem, i build a LM317T reg after the 17v.
      Every voltages are ok, but with the heater connected, the 7660 get warm and the volatges goes wrong.
      Did you found a solution ?

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  40. Hey there. 1/4 watt resistors alright with this? Thnx!

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    1. yep. you should be able to get away with 1/4watt resistors for all pedal projects. btw, i for those in the know, i have finally fixed the stupid johns. about damn time!!!! :)

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  42. Where can I buy a terminal strip like that please? (1st layout on page top)

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  43. Ok, found that terminal strip. One more question about the charge pump please: possible to add 2 more "steps" e.g. adding 4 more caps and 4 more diodes to get about 50v on the output?
    Thank you.

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  44. I would like to use it with line signals. Low impedance and a lot of gain in the input.
    Could you tell me the mods to use like a line buffer but like it is?
    A line buffer with gain/distortion control.

    Perhaps I need to change the value of several caps because I need the complete range of frequencies.

    I would like somebody tell me the way. Thank you.

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