ElectroVibe Modifications Thread

[joelorigo]

Switch numbering
3 5 6
2 4 7
1 4 8



While the connections you've drawn will work, generally speaking the lugs on a 3PDT are typically numbered thusly:

1 4 7
2 5 8
3 6 9


I only bring it up because it may help in future communications with other builders about circuit wiring etc.

Yes, thank you, I noticed that numbering was not normal, I was copying the numbering from a post earlier in the thread (#33) who was addressing the same topic but wasn't sure why it was different.

 

[markuus]

Has anyone done any of these mods on the Electrovibe Mini by chance? As @Big Monk noted in a different thread, the capacitors and resistors are numbered the same way across the two versions, but the transistors are numbered differently.

I'm a bit stuck planning out an upcoming Electrovibe Mini build because I'm not sure which transistors to swap out.

 

[Big Monk]

Has anyone done any of these mods on the Electrovibe Mini by chance? As @Big Monk noted in a different thread, the capacitors and resistors are numbered the same way across the two versions, but the transistors are numbered differently.

I'm a bit stuck planning out an upcoming Electrovibe Mini build because I'm not sure which transistors to swap out.

I haven’t dug into yet as I’ve got other projects ahead of it.

Honestly, the transistor mods are likely to be the least value of all of them. If you’re in a pinch, just skip them.

 

[markuus]

@Big Monk All good, just checking. I'm also probably not going to build this for a while, but I was buying some parts for this and a few other builds and so was looking at these mods and taking note of what I wanted to do for future reference. I grabbed the alternate transistors for this project in my last Mouser order.

I'll poke around on here again when I get around to actually building this. Maybe someone will have figured this out or the EV Mini schematic will be available by then. Not too stressed about it.

Thanks!

 

[markuus]

@Big Monk Actually realized I could figure this out and poked around checking continuity on the ElectroVibe Mini boards. I think I identified the counterparts to Q3, Q4, and Q14.

Reliability mod (2N3904)
Q13 and Q14 on the EV Mini LFO board seem to correspond to Q3 and Q4 on the "regular" EV board. I found continuity between the lamp, Q13, Q14, R26 and the Gain trimmer in the Lamp Driver section.

Darlington mod ( MPSA13)
Q10 on the EV Mini audio board seems to correspond with Q14 on the regular EV. There's continuity from Q10 with R27/C20, R56, and C28.


EDIT:
Also just noticing the parts list doc calls the transistors on the LFO board Q1-Q4, but those are actually Q11-Q14 as noted on the PCB diagram on the product page for the ElectroVibe Mini here: https://www.pedalpcb.com/product/pcb448/

 

[ptone]

@Big Monk Thanks for posting these mods. Unity gain and max speed mod worked perfectly for me. I used 2.2m on R4, and 2.7k on R14/R15.

 

[The Gator]

Hey thank you for posting all of these mods and the great high lighted sections and details!
I am getting ready to start building mine.
I was wondering what some of you used for your sheild around the bulb and the LDRs? Some sort of small plastic cap or?

Thank you
~ Gator

 

[zgrav]

Hey thank you for posting all of these mods and the great high lighted sections and details!
I am getting ready to start building mine.
I was wondering what some of you used for your sheild around the bulb and the LDRs? Some sort of small plastic cap or?

Thank you
~ Gator

I think I used a screw-on cap from a 2 liter soda bottle.

 

[Big Monk]

Unless you are going to use a cap that has an inner reflective surface, you only need the cap for setting the pedal up. Use any old hodge-podged thing for setup then chuck it.

 

[The Gator]

Thank you for the replies.
I am looking at the different mod schematics posted early in this thread and noticed in the analog LFO portion of the circuit. one schem shows a darlington in place Q1 and Q2 (or a darlington in each position?). The other schem does not show this.
Any help would be appreciated.
Thank you
~ Gator

 

[The Gator]

Nevermind. I think I understand now.
Different question: if you mounted the LDRs and the bulb on the other side of the circuit board, you could put a red lens there and change the trim pots out for surface pots to dial in the the bias and gain. The question being, any body think of a reason this wouldn't work?

 

[Big Monk]

Nevermind. I think I understand now.
Different question: if you mounted the LDRs and the bulb on the other side of the circuit board, you could put a red lens there and change the trim pots out for surface pots to dial in the the bias and gain. The question being, any body think of a reason this wouldn't work?

As long as there is no light pollution from outside the enclosure then it should work.

I don't see a pressing reason to have the lamp controls external though but I did contemplate for a time.

 

[The Gator]

Oh. I guess I totally missed what the extra pots are on your original build.
I like the simple rate led mod.
I just thought about doing the flip side install before I saw your rate led mod.
I think I will look at the data sheet for the P9203 LDRs i have for the project to see there sensitivity to different colors orvif they "see" the whole visible spectrum equally.
That would dictate whether or not to bother with flip side mounting or just do the rate led mod.

 

[The Gator]

Well, they are extremely broad spectrum LDRs, so leakage of light would be a problem. Unless a purple lens was used. Also physically having the bulb on the flipside means spacers would be required on the pots for installation to bring the board lower. This makes for a tighter install in the recommended 1590BB.
This makes the rate led mod look like a easier/better idea.
I probably need to just calm down and build the pedal. ..lol
Not sure I'm gonna change out a lot of the caps. Probably just do the various resistor based mods.
Thank you for your help and for this information.

 

[Dman]

I've discovered that a cap to a chapstick fits snuggly over my LDR array.

My build couldn't fit any tighter in a 1590bb. After grinding down the base of my dual pot the bulb barely touches the lid. Wish I'd used a 1590bbs or Gorva.

So . . . I think I need to do the the Keen stereo mod.(http://www.geofex.com/Article_Folders/univibe/univtech.htm) But I've run out of room for another 1/4 inch jack. I'm wondering if I use a stereo output jack will it damage the circuit or alter the sound if I plug a mono jack into it?

I could use a 3.5 mini stereo jack instead.

Thanks for any words of wisdom,

Don

 

[The Gator]

I could use some opinions of those who know more than me.
In the lamp driver portion of the circuit R22 and r26 are on both sides of the bias pot and are 47k. I just ran out of 47k but for some reason I have 51k and 43k. So the questions are, if you could replace these with 51k or 43k would it be a problem and which one would you use? Basically you are increasing or decreasing the total overall by 8K in that portion of the circuit.

Thank you in advance for your help.
~ Gator

 

[Dman]

I'm not a EE, but those two resistors look like they form a voltage divider circuit to me. I think as long as they are kept the same the voltage is divided evenly. I'd go with 51K.

I think the bias is adjusting the voltage difference between the base and the collector of Q4 so that the base of Q3 gets the right amount of signal to effectively modulate the lamps access to ground.

You could also put two 95k in parallel to create 47.5k.

Hope this helps,

Don

 

[andare]

I'm putting together my build.

The mod for slower speeds is changing the value of R12 from 2M2 to >5M or exactly 5M?
All I have is 4M7 and 5M6. Which one should I go for?

 

[andare]

Bumping this up because I'm too dumb to choose for myself. Is R12 supposed to go above 5M Ohm for slower speeds? If so, am I good to go with 5M6?

Thanks

 

[Big Monk]

Bumping this up because I'm too dumb to choose for myself. Is R12 supposed to go above 5M Ohm for slower speeds? If so, am I good to go with 5M6?

Thanks

I think changing the middle cap in the LFO string from 1u to 2.2u has a greater affect, per my conversations with @Chuck D. Bones

Just make sure the caps in that LFO string are tants or film.