mid-fi clai(not) schematic!

[doc_drop]

I see. It is a pretty simple concept that was easy to understand as I read up on how people use these in a circuit.

Now practically speaking as far as my build, I saw what the box looks like in the videos. The LED is mounted like in a regular stomp box. I don't see any LDR on the exterior, so where is it? How does the light of the LED hit it? And since there are no values given, and no color for the LED, what kind of LDR should I use?

Ideas? Thanks!

[doc_drop]

I think I found what I'm looking for...

http://www.alliedelec.com/Images/Products/Datasheets/BM/PERKINELMER/PERKINELMER_ACTIVES-AND-PASSIVES_9800700.PDF

[Barcode80]

yeah i was just going to post that the status led is not the led in the led/ldr combo. You can also make your own vactrol by getting an ldr at radioshack and heatshrinking your own led to it.

[doc_drop]

So, I ordered 3 different types of these variactors from Allied. I figure I will try all 3 to decide which works best. I actually found the part number from ROG's phasor project, via Google. I'm kind of excited about this "new" part, and the circuit snippet for it. I am wondering what else it might be used to control...

Anyway, I should have this guy bread boarded in a week, once I get all the parts. We'll see if I can get it working.

[Arn C.]

Doc_drop,
     Let us know for sure which Vactrol works the best .  I have a few left that I will use for this project.

Thanks!
Arn C.

[doc_drop]

Sure Arn. I will definately post a build report for this one.

[orangetones]

I used a homemade photocoupler for this on the breadboard and it worked just fine.  I can check the value of the LDR in that on, but I think it was around 5k-500k.  I would suspect most would work fine in this circuit.

[doc_drop]

The ones I ordered were the VTL5C1,  VTL5C2 and VTL5C4. I guess I'll see which works best once I get them and plug them into the circuit. The biggest difference I see is that the VTL5C2 has a turn off time of 500ms and the others are 35ms, so I guess that would be a big difference in how the thing tracks picking strength. I am looking forward to hearing the results.

[orangetones]

If I remember correctly, from that other site, the original uses a bright white LED and an LDR, not a commercial photocoupler.  Again, not sure of the resistance on the photocoupler.

I did notice that with this circuit you adjust the brigthness of the LED with the controls though, so having the right range might not be an issue.

I get what you are saying about the fall time of the photocoupler though.  Should produce a bit of a different sound, however, hifidelity and this circuit are not synonymous.

Do let us know what you think once you get your order.

[orangetones]

Here is a quote from the designer himself from that other forum, where you will also find perfboard and PCB layouts...
___________________________
Q: Maybe if Danelectro gets a hold of that schem they can build one cheap enough for all of us to afford.  Just kidding of course. On a serious note , what is the range of the photo cell?

A: doenst really matter, as long as it gets down under 5k or so, and goes about 200k your good.

_____________________________________________

Now that doesn't mean you need that exact range, just to be able to reach those ranges.  Cheapo Ratshack LDRs should work for this, with red, yellow, or white LEDs.

[doc_drop]

Interesting orangetones.

I'm afraid I don't know what the "other" site is, so I haven't been able to read that. Thanks for sharing.

[doc_drop]

If you guys are interested, I posted my build report here:

http://www.diystompboxes.com/smfforum/index.php?topic=75365.0

Short story: This guy RAWKS!!!

[snap]

well, since the originator is here,
why not ask himself?

[frequencycentral]

I've done this perf layout, I've got all the parts, just need to get it built. I think the layout is correct. I'm planning to mount the LED/LDR and output cap onto the pots to keep wiring down to a minimum. Would some kind person check it over please?

[doug deeper]

fyi the perf layout in the other thread is the exact one i use!

[frequencycentral]

fyi the perf layout in the other thread is the exact one i use!

Thanks Doug, but I wanted to do my own layout to suit the way I'm planning to box it up. By the way, which pots are LOG/LIN? The schematic isn't specific. Thanks!

[Cardboard Tube Samurai]

I used all linear pots except for the volume. Works fine

[frequencycentral]

I used all linear pots except for the volume. Works fine

Thanks, that's what I figured. I just didn't want to risk putting it together with the wrong pots and have to change them later.

[cheezit]

I'm looking at the schematic and wondering---just where is the "fuzz" coming from?  It would have to be the LM386 going full tilt, right?  I don't see clipping diodes or cascaded transistors anywhere...driven hard, the PT2399 might add some blatty grit, I suppose.

[bluesdevil]

Connecting pins 1 and 8 together on the 386 is what's doing it I believe.