Diezel VH4 Pedal  [schematic]

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

What do you use to attach the voltage regulator to the board? To help heat sink it.

bmxguitarsbmx
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Post by bmxguitarsbmx »

caspercody wrote:What do you use to attach the voltage regulator to the board? To help heat sink it.
To sink what heat? Not being snotty, but the TO-220 package could easily be dropped to a TO-92 package and use only air cooling:

https://www.mouser.com/ProductDetail/ON ... %2fRhHA%3d

^100mA TO-92 12V linear regulator

caspercody
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Post by caspercody »

I ordered a kit, and it came with the LM2940CT-12.

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Post by Svullgo »

First I wanna say thanks to all you heroes who put down a lot of time in this community and sharing your results and knowledge!
You have helped me a lot in learning and understanding the electronics of pedals!

I have built this after Alex Vero at tagboardeffects and everything works. (I needed to up the the 47p capacitor to 560p as reichi suggested to get rid of the oscillation/feedback on higher gain levels)
I wonder if the presence and resonance works as the original (which I never have tested)
The presence lowers the the perceived volume a lot when turned down and resonance feels like its to much in the lower midrange. (but thats what Bajaman on page 4 says that they should do but have anyone have had the opportunity to A/B-test it with an original?)

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Post by Daza »

I set the bass version, and I also have oscillation with high gain (around 12 o'clock) I'll see if it goes down changing the 47p

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Post by Daza »

Daza wrote:I set the bass version, and I also have oscillation with high gain (around 12 o'clock) I'll see if it goes down changing the 47p

I set the bajaman version, and I also have oscillation with high gain (around 12 o'clock) I'll see if it goes down changing the 47p

brejna
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Post by brejna »

It does, but pedal sound muddier...

bmxguitarsbmx
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Post by bmxguitarsbmx »

The real way to tame oscillation is to examine the layout. IMO

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Post by Daza »

It would not be good muddy sound.
I put shielded cable and it improved a bit. Increasing the depth increases the oscillation considerably

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Post by Daza »

Will you have a problem with the input impedance the scheme?
I put a buffer before the pedal as recommended by Brejna and the oscillations disappeared!

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J0K3RX
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Post by J0K3RX »

I wouldn't bother with shielding the output... I would shield the input and definitly the gain pot! Poke around with an audio probe and it should lead you right to the source of the oscillation...

bmxguitarsbmx
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Post by bmxguitarsbmx »

I wish I could attribute this quote pertaining to pcb layout:

"rarely will stray capacitance to ground cause the problems that stray capacitance between any other traces have".

Shield it up! Proximity/phase is also worth considering.

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Post by sego91 »

Im gonna try to replace the 7660s with another IC to eliminate the oscilation and squeel, maybe a 1054 im gonna check it out .

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Post by RockKenny »

sego91 wrote:Im gonna try to replace the 7660s with another IC to eliminate the oscilation and squeel, maybe a 1054 im gonna check it out .
Hi! Any good news after changing 7660? I'm also have oscillation problem & no ideas how to fix...

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temol
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Post by temol »

I've completed my VH4 build. Worked on first try, no oscillation. Because I did not have 25kC potentiometers, I used 25kB with an additional resistor, which was supposed to change the pot characteristics from LIN to ANTI-LOG. Unfortunately, it does not work as it should. In my opinion it still works as a linear potentiometer. It worked on a breadboard - I connected battery to the potentiometer, measured voltage, plotted a curve - definitely C characteristics. Maybe I should try with a lower resistor value. Now it's a 5k1 across leg 2 and 3.

T.

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Post by Silverhair »

Maybe the TC1044SCPA, in this version they use it: http://www.pedalpcb.com/product/valhalla/

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temol
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Post by temol »

I have 7660SCPAZ in my build and no oscillation.

Image

T.

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bajaman
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Post by bajaman »

nice build :D
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Post by RockKenny »

temol wrote:I have 7660SCPAZ in my build and no oscillation.
T.
What kind of 7660 do you use? I mean firs letters.
I have oscillation with ICL7660SCPA.

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bajaman
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Post by bajaman »

No problem with any oscillation my board layout as Temol has found :roll:
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