This one needs an 18V supply, so use a dedicated supply, two batteries, or you could build up the 9V to 18V converter that I've posted
here. Best results may be obtained if you heat shrink the LED and LDR together or at least wrap a bit of electricians tape round them both.
Tag it - with couple of notes...
ReplyDeleteCircuit works as it should and sounds good. Like someone said over the interwebs, it's more like a sustainer than a compressor.
Anyway. I built it with 18V pump, BC549Bs (measuring ~320 hFE) and custom made optocoupler. The LDRs i have seem to go only up to 60K of resistance when dark, so that makes the sound go overdrive. After socketing and lots of trial & error, i figured that the LDR should ideally be at least 500K when dark. I guess that 50K light and 1M dark would be optimal. Anyway. Since the 60K dark was (and still is) all i have, i upped the bottom 100R for 470K and used what i had for LDR. It works, but it is somewhat impaired. Of course it is, as it should let the LDR control 500K of resistance instead of 50K. It still works and sounds good. I'm happy with it.
If i get my hands on more suitable LDRs, i might swap it and the resistor...
Another one bites the dust! Is it now 11 'till 300? :)
+m
Oh. Yellow 5mm diffused LED :)
Delete+m
I just remembered that i had one "spare" VTL5C1. Sticked it in and it's better. Much better.
DeleteIt still get kinda dirty, but placing a 500K trimmer in place of bottom row 100R would be a good idea to clean it up a bit.
I do think my choice of transistors may be the main cause for the dirt. 300-330 hFE may be just a bit too much.
Nice project though. But nowhere near the more modern compressors. Although i like this, it's not going to replace my dyna clone.
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Awesome, nice one Miro. Nearly there! :o)
DeleteHaving trouble with a bad hiss in the mix when the led /ldr is added, no matter what the led ldr combo is, also have to put both pots to full to match dry signal
ReplyDeleteAny idea where to start the debu
My electrolytic caps are only rated for 16v would that cause a hiss
ReplyDeleteIn my original Colorsound pedal, the led/ldr has been replaced by a Clairex CLM6000 fromSmallbear. It works like a charm!
ReplyDeletewould you say it has more sustain than a ross comp or dyna? im looking for a little more sustain
Deletedoes this yield a little more sustain than the average compressor like the ross and dyna or about the same??
ReplyDeleteBreadboarded this circuit, last night. Originally used a 500k LDR but when it became clear that this was more of a sustain circuit than a compressor circuit, I switched to a 1M LDR and I like it, much more. I tried using a phase inverter and another couple of transistors (I used 2N3904 transistors, all around) to get a less "spikey" current flow through the LED and also added a 10uF cap to smooth things out, even more. In the end, I just kept the 10uF cap but added a 500R trimmer in series with a 100R resistor in place of the 470R CLR so that I could fine tune the current going through the LED. I am adding this to my board after a treble boost that comes after my main compressor (a modified DOD 280A clone). That combination, feeding into my preferred overdrive, distortion, or fuzz pedal yields an incredible amount of sustain.
ReplyDelete