Friday, 20 April 2012

Dallas Rangemaster

As requested.


24 comments:

  1. Thank you very much for posting this,been wanting to do one for a while:))

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  2. hey IvIark, do all 3 legs of the trimpot go to something?
    i just built this on turretboard, it does work.. well sorta.
    i used an ac128 transistor, the trimmer doesnt do anything to it! also, it is quieter than unity. should i go to a diff tranny?

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    1. Hi Brian. The trimmer is just being used as a simple variable resistor and so only the two connections shown need to be made. If you say the trimmer doesn't do anything then something must be wrong because moving that will alter the bias of the transistor and so should definitely affect the sound.

      Are you sure the wiper and one of the legs are connected, and not both legs? Because if the wiper isn't connected to one of the connections shown, then it won't do anything.

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    2. pretty sure, wiper is on top and the 2 legs are on the bottom. i can say that with a fet booster in front of it, it fuzzes up nicely. i might try out a diff germ tranny and see if it does anything.

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  3. Hi Ivlark,
    I was just wondering how this circuit differs to the original Rangemaster circuit. This is because your circuit uses resistors of different values to the original and also has a trimpot. Does this affect its tone at all?

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    1. The only differences are that I have used the common 4n7 value instead of 5n, and have included a pulldown resistor at the input and output to counter pops and clicks. The trimmer should help fine tune the effect and would be set to 3K9 if you want to mimic the original values.

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  4. may I use AC125 or AC128 and if yes what about the Hfe ?
    Thank you very much Michael

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    1. You can use anything, in fact I would encourage you to try anything you can get hold of so you can see how much of a difference the different types, makes, gains etc make to your ears.

      I think around 100hfe seems to be a commonly quoted number but again try a few and see what gain react best for you with your guitar and amp. Remember this is all about getting the best response for you personally and no one can tell you what will sound best with your gear.

      Socket and experiment with a few different types, you don't have to spend a lot of money, particularly if you look at some of the Russian germaniums, but it's well worth doing.

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    2. Incidentally, this is a highly recommended read about the Rangemaster. RG has answered most questions here so it's really good if you want a broad understanding of what is going on under the hood.

      http://www.geofex.com/article_folders/rangemaster/atboost.pdf

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    3. Thank you very much indeed Ivlark

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  5. Hi there guys, I built this the other night.
    Well, I sort of built this. I didn't have the right transistor for it.
    So I decided to make a silicon version and see what works.
    I put in a few different ones. 1 type was weaker than a wilted flower, a few were not too shabby at all.
    Though I plonked in a bc183, and it was an overdrive pedal suddenly.

    I did change the input on output caps, I don't have the values with me, but I shall post them when I do.

    I'll let you guys know how it sounds next week. I have the shitest amp to use in the house so I can't tell what the tone's like, till I get to my good amp.

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  6. What wires would I switch in order to use an AC128 Germanium NPN Transistor?

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    1. If you have a NPN AC128 germanium... more than switching wires you should keep it and sen it to a museum :P

      If you want to use a germanium or silicon NPN, then you have to turn around the electrolithic caps. Then +VE will be the +9v wire and the -9v will become th ground.

      BR

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    2. I think Javi tried to point out that AC128 is PNP transistor. AC176 is NPN.
      +m

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  7. I'm sorry copy and paste error... I meant GT-AC187 Germanium NPN Transistor

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    1. No problem, it was just a joke :)

      As previously told, you just have to turn around the electrolithics and use +VE as +9v and -9v as ground, that's all :)

      BR

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  8. Which cap should I make switchable to get an option like the Cream/Spike switch on the MJM Dallas Boost?

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    2. This circuit is easy to build and really difficult to adjust.

      First, the trannie has to be really gainy and with very low leakage (in my experience < 0,1)

      And second, the collector has to bet set over 7volts (if the tranni is leaky, you'll never get similar values).

      Once checked this issues, you have to remember that the effect is very noisy, the knob crackles and you'll only perceive a use of this knob in the last quarte CW.

      J.

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