EHX - Mini Q-Tron  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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floris
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Post by floris »

Thanks! That's great! I see already (miniqtron.pdf) that changing R21 (33k) to a pot (say 100k) will get me a good variable attack. Wonderfull!

Flo.

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Dirk_Hendrik
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Post by Dirk_Hendrik »

and that's a goner...

suggested reading for the fella who is suspected te be behind it:
http://en.wikipedia.org/wiki/Don_Quixote

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xaxxop
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Post by xaxxop »

Hi, Can someone raise the file? :(
Leandro

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floris
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Post by floris »

You have a PM.

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rs
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Post by rs »

Yeah, if someone could raise the file that would be great!

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xaxxop
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Post by xaxxop »

thanks, floris! :D
Leandro

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alman
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Post by alman »

Hi there, I would also like the schem if possible. I have a guy who wants a pedal similar to this but wants it made to be his own.

Allan

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ianZeds
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Post by ianZeds »

Hi,

I've managed to break my mini Q-Tron by trying to wire a centre negative power socket, I think I reversed the polarity by mistake, any advice on how to fix this or which components to swap out first would be much appreciated!

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floris
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Post by floris »

Hmm according to the schematic, it has a protection diode D1 in series with the power rail so it should not have broken down by the reversed polarity.
Connect the power again (correctly!) and measure the voltage on:
- C8 (100uF)
- Vbias voltage divider R16 & R17
- Pins 4 & 8 of the opamps U1 U2 U3

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ianZeds
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Post by ianZeds »

Hi, Thanks for your reply, I will check those when I get home this evening, I should add the center negative power socket was made of metal, is it possible the power could have affected anything grounded to the case?

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floris
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Post by floris »

If you use a metal DC jack which connects to the metal FX enclosure then the outside MUST be Ground and the center pin must be +9V or else it does not work.
The signal jacks are also connected to the enclosure with Ground and that shorts the power in that case.
Only with an isolated DC jack can you use the "plus on the outside" & "ground on center" connection.

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floris
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Post by floris »

@Lejeune: You have a PM.

Please do not post your email address in plain text format here, the "spambots" on the internet will use it.

Please return the favor to others!

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celadine
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Post by celadine »

A redraw for your pleasure:
miniqtron.PNG
Lemme know if theres mistakes or whatnot.

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SPeter
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Post by SPeter »

Attachments
EHMINIQTRON.pdf
(171.72 KiB) Downloaded 258 times

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wareck
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Post by wareck »

Hello everyones..

I have 2 questions:

-There is the possibility to buy this stompbox kit ? (pcb+component)
-Where did I could find the HTV - P873-13 ?

Thanks in advance

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jonfoote
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Post by jonfoote »

hi, ive got a question about those 2 diodes in the envelope. (11DQ03 or IR9830 and the 1N5229B)

can i replace them with either LEDs or 1N4148s?
id rather use something ive got a lot of than buy a couple of odd bits.

ta

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erratom
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Post by erratom »

thanks a lot.

I would like to add a “direction filter” : up or down, anyone knows how to do it ?

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Post by kelsonbueno »

Hello everybody, I built the effect basing myself in the following diagram electronic pdf, but I have identified that the zener appointed as D4 - 1N5529B actually is a zener of 9.1v, and the scheme is written 4.3V (in my particular I I used a 1N4731 zener 4.3V). I was confused and the effect does not seem to be working well.

I built on a perfboard replacing two TLC2262CP by a LM324N in order to save space, and am doing a debug correcting links I had forgotten. If anyone has a credible blueprint, or could check with the effect the voltage at the point of D4 and its name, I appreciate that!!!

file: http://www.sendspace.com/file/sj8xui
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aaminiqtron.pdf
(22.35 KiB) Downloaded 440 times

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johnk
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Post by johnk »

zombie thread alert.
I just built one last night according to the EHX schematic posted , but using two VTL5C3 vactrols for the opto device. it doesn't work at all so i'm now questioning the accuracy of the schematic.

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Blitz Krieg
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Post by Blitz Krieg »

the schematic is nearly identical to the original qtron, the mu tron, the qtron+, and the foxx footsynth.

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