Pages

▼

Tuesday, June 11, 2019

EQD Bows

Here's Jamie's take on the classic Rangemaster circuit, with a NPN germanium transistor. There's an added toggle to switch between full range and treble input caps. Probably a tight a squeeze in a 1590A but should be doable. There is also a 1590A specific PCB with board mounted pot and switch in the store now (link below).

at

37 comments:

  1. ThafaJune 17, 2019 at 7:42 PM

    Plissss post skema "napoleon booster" original,,thnk you frns

    ReplyDelete
  2. DeeJune 20, 2019 at 11:00 PM

    Is there a schematic for this ?

    ReplyDelete
  3. JimSJune 21, 2019 at 3:59 AM

    Any idea on ideal hfe for the transistor?

    ReplyDelete
    Replies
    1. Effects LayoutsJune 21, 2019 at 10:36 AM

      Pretty low. The transistor in the one traced on FSB had a hfe of 35. Higher gain transistors can be used, you'll just need to adjust the value of the resistor going coming off the emitter to bias it correctly.

      Delete
  4. GeneralBlotoJune 22, 2019 at 7:16 PM

    That OC139 is pretty tricky to find. Do you know any direct replacement that i could use? Thanks.

    ReplyDelete
    Replies
    1. Effects LayoutsJune 22, 2019 at 10:53 PM

      Anything low gain will work as I mentioned above. You just may need to adjust the value of the 100Ω resistor coming off the emitter. In a typical Rangemaster that resistor is 3.9k.

      Delete
  5. skizoideJuly 9, 2019 at 8:58 AM

    I'm the only one who needed to reverse the orientation of the transistor? I tried a few different ones, and I'm sure of the pinout (used an DCPeak Atlas DCA model DCA75), and the emitter and collector are reversed, in this layout and in the original schematic traced.

    ReplyDelete
    Replies
    1. collinlylecarterSeptember 25, 2019 at 12:11 AM

      You aren't the only one. I bought a QC139 and found that the orientation was backwards. I'll have to do some more fiddling with the resistor coming off the emitter, however, to determine if really needs to be reversed. TBD.

      Delete
  6. ThumpTwangAugust 1, 2019 at 8:35 AM

    Sounds fantastic! FWIW, I biased an AC187 with 3K.

    ReplyDelete
    Replies
    1. FireproofAugust 30, 2019 at 1:06 PM

      Hi, I have an AC187, where you put the 3K resistor? tnks!

      Delete
  7. FireproofAugust 30, 2019 at 9:06 AM

    Any replacement for 5817 diode? I have 4148, 1n34a, 4007.

    ReplyDelete
  8. FireproofSeptember 19, 2019 at 9:38 AM

    Hi, I used an AC187 and placed a 10K trimpot instead of the 100 ohm ground / emitter resistance, but the trimpot has no effect, the sound is always the same, any ideas? (I also put 100k and 220k in parallel instead of the 68k resistor)

    ReplyDelete
  9. mgnMarch 13, 2020 at 3:01 PM

    This may be a dumb question but what voltage should we bias the transistor to?

    ReplyDelete
  10. ZZOYDAugust 3, 2020 at 1:57 PM

    Built it! I used b500k & 4n7, 22n, 0.1 caps see there: https://imgur.com/a/VhD6eCm
    68k bias i used 82k. ge npn mp38a hfe=90. Realy good working with fuzzes!

    ReplyDelete
  11. veggamanAugust 18, 2020 at 5:54 PM

    Hi, how to put a pregain on this (like on the Analogman Sunface) ?? What pot to use and how to hook it up? :)

    ReplyDelete
  12. veggamanAugust 23, 2020 at 5:43 PM

    Pleaaaaaas anyone !! :)

    ReplyDelete
    Replies
    1. ZZOYDAugust 27, 2020 at 8:51 AM

      or like there https://effectslayouts.blogspot.com/search?q=royal+tone+bender

      Delete
  13. ZZOYDAugust 27, 2020 at 8:48 AM

    do like there https://effectslayouts.blogspot.com/search?q=katzen

    ReplyDelete
  14. veggamanAugust 31, 2020 at 4:11 AM

    Thanks a bunch :)

    ReplyDelete
  15. BoukmanOctober 14, 2020 at 9:56 AM

    Hi i built it with a 5k trimmer in place of 100ohm with ac179k.I can get to 6v at the collector.In full range it is ok but in the treble position i have a lot of noise..Is this normal or it depends on the transistor?Thanks

    ReplyDelete
  16. Timothy ShieldsJanuary 22, 2021 at 2:44 PM

    I have a Philips Valvo ASY29 NPN Germanium transistor, hfe = 135. Would I be able to bias with the emitter resistor, or would also have to change the resistor leading to the bias of the transistor?

    ReplyDelete
    Replies
    1. Effects LayoutsJanuary 22, 2021 at 3:21 PM

      I'd start by tweaking the 68k resistor for the base to ground.

      Delete
  17. Timothy ShieldsJanuary 23, 2021 at 4:46 PM

    Thanks, I'll read up on how to calculate and measure the adjusted hfe.

    ReplyDelete
  18. BoukmanMarch 25, 2021 at 10:57 AM

    Hi!How did you wire the pot in place of the toggle?Thanks!

    ReplyDelete
  19. Unkle PhilApril 27, 2021 at 10:33 AM

    Great !
    How do you wire the pot?

    ReplyDelete
  20. Unkle PhilApril 27, 2021 at 10:35 AM

    Maybe my question is stupid , but... could I use a NPN silicon transistor?

    ReplyDelete
    Replies
    1. Effects LayoutsApril 27, 2021 at 4:35 PM

      It would need to be very low hFE. A 2N2369 might work, but might still not bias correctly.

      Delete
    2. Unkle PhilApril 28, 2021 at 2:52 AM

      Thanks a lot !

      ... and by the way: thanks for your PCBs, they are great!

      Delete
  21. Unkle PhilApril 28, 2021 at 2:51 AM

    This comment has been removed by the author.

    ReplyDelete
  22. Unkle PhilJuly 2, 2021 at 7:13 AM

    Hi,
    I build a Beauregard pcb, with an AC176, and a 5k trimmer for R5, easier to bias it.
    The treble position sounds great, but the"full" one is really really loud.

    ReplyDelete