Saturday, 15 February 2014

Dallas Rangemaster PNP negative ground

Request.  Moving on from the Fourbanger, here's a compact layout for the standard Rangemaster but with a voltage inverter so you can use the better quality PNP transistors but with a negative ground.  Note the IC is rotated 180° to how we usually mount it, pin 1 bottom right.




To make this a little more versatile I'd be very tempted to lose the input and output caps (and shave off a column) and add a 4P3T rotary switch to swap input and output caps to offer a greater range of frequencies.




Maybe having:

Input caps
C1 - 5n
C2 - 22n
C3 - 47n

Output caps
C4 - 10n
C5 - 47n
C6 - 100n

or whatever suits your taste and equipment.


Oh and the collector/emitter swap cheat version for Travis, not sure how well this will work though!:o)


28 comments:

  1. Cool layout and great suggestions for the cap switch.

    Personally I would prefer to see one without a charge pump, set up similarly to the Fuzz Factory using PNP in a negative ground circuit.

    I might be biased against charge pumps though, because they're kindof expensive and noisy in my [limited] experience with them

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    1. Travis, They're not that expensive if you get them from overseas etc

      http://www.ebay.co.uk/itm/20pcs-ICL7660S-DIP8-Voltage-Converter-/390341332047?pt=LH_DefaultDomain_0&hash=item5ae2280c4f

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    2. See above, I still think I'd prefer the charge pump though!
      18p each here :o)

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    3. I'm curious, why do you prefer a charge pump? I've read that the "cheat" can result in oscillation sometimes, but I haven't experienced that before

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    4. One reason is that although I've heard people complain about noise with a charge pump, I haven't heard anyone complain when the IC is just providing a negative voltage rather than voltage doubling. Maybe that's just my own perception but I can't remember seeing anyone post about noise when they were just using the IC to get -9V. Secondly is because the transistor isn't symmetrical and so it won't behave when reversed necessarily in the same way it would when used in its intended orientation. Gain will possibly be lower and it will clip differently.

      I'm not against it because the anomolies of it may actually be pleasing to the ear, and as the only real measure is how these things sound, the theory behind it all takes a back seat. But my reservation is when I want something to sound like the original, and then I would be less likely to use it.

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    5. I see. Thanks for the explanation

      I built a fuzz face type circuit with the 7660S providing 9v- and got excessive noise. I tried several of the usual fixes for noise and the only thing that worked was ditching the charge pump.

      All of my voltages looked good but it was just really noisy with that charge pump. For better or for worse I mostly lost interest in them after that

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  2. O wow, that schematic for the switch is really cool!

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  3. Also thanks so much for listening to my suggestions! I look at this site everyday you guys are my favorite

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  4. Very excited about this! I was planning on build a new rangemaster soon. I love the Idea of the switchable caps too.

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  5. For anyone wanting to try the switchable caps in this or any of the other effects, this is a pretty good price:

    www.ebay.co.uk/itm/190934769333

    With it having the same split shaft as the pots we often use we could use the same sort of knobs and for this effect I think it would look quite cool to have a 2 knob Rangemaster with the usual Boost pot and a 3 position Tone control next to it with the same chickenheads or whatever.

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  6. Hi Mark, may I ask layouts using cheaper chargepump like NE555?

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    1. You can't do it with an NE555 I'm afraid, the largest negative voltage you can get from a 9V supply is -6V so it just isn't suitable for the circuit. You can get the ICL7660S cheaply though, here you can get 10 for $4 which will let you build a lot of these effects.

      http://www.ebay.co.uk/itm/370536923495

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  7. Hi Mates,

    My experiences with the 7660S and its different configurations are not all ok:

    - With the Klon, used as doubler, sounds great and no noise.
    - With the Mutron III: sounds great, no noise at all
    - With the Meatball: perfect sound, no noise at all
    - With the OKKO Diablo: Infernal whine when set to 18v, totally useless.
    - With a Fuzz Face: (as inversor) Noticeable noise, and tamed fuzz, not recommended.
    - With a Tonebender MKII: (as inversor) Noticeable added noise and slight oscillation when gain is al high values. Not recommended.

    So, in my opinion, this ic is not recommended at all with germanium builds as inversor and neither medium - high distortions as doubler. The only overdrive - disrtortion effect where I have had no problems, has been the Klon.

    Of course, this is my experience but I'd like to share it.

    J.

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    1. Thanks for the feedback guys. I wonder whether a different IC like the LT1054 would do a better job. A bit of experimenting may be called for.

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    2. I've made a few Tonebenders with the voltage inverter and have never had nouise or oscillation. And a few Ge fuzz faces with it too. That's just my experience. Although when I used a cheaper power supply, I had noise on the Fuzz face.

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    3. *Noise. And to add, I've always used the 76605

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    4. Yeah that's been my results too mate, never had one issue other than when I bought a non-S version by mistake once.

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    5. Yeah, first time it happened to me, I thought it was a defective batch, so I purchased another lot for a different seller, even though it was the same ones that used for the Klon and the Mutron III (a 100 pieces order). Had same results (npise) with the Okko and the Tonebender using the new batch, so I'm right now building a new MKII without inverter, and never built another Diablo :)

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    6. I did read someone say that the Openhaus sounded awful with a charge pump to get the 18V and you should always use a dedicated supply or just run it at 9V. So some circuits are obviously sensitive to it.

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  8. I've never gotten a MKII Bender to work on a power supply at all. It's always super noisy and oscillates. It's probably just my power supply, but since I use a one spot or BOSS PS I figure many others would have the same problem if I sold one that way

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  9. any suggestions for the Hfe transistor? Thxs!

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  10. Any pnp transistor with an hfe between 80-100 would be fine. Leakage 100-200 micro amps. :)

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  11. ICL7660S version with tone switch is verified. Used a Russian Mn39b (hfe 39) and C5 68n. No noise whatsoever.

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    1. Awesome, you're on a roll! :o)

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  12. Does it sound good with such a low hfe? I don't care too much to pick my transistors in the suggested ranges as long as it sounds good, but that's pretty low.

    I guess I should just put a rangemaster on my breadboard to find out for myself :P

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    1. Because of the low hfe there is not a whole lot of boost like you would have with a higher hfe including lots of gain. However there is a slightly cleaner boost which is useful in combination with the tone control. Basically the version I made is a simple EQ with three settings. Perfect in combination with a tube amp.

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  13. Hello!!

    I'd like to know how to adjust the trimmer.

    You're all are doing a brilliant job¡¡

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