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Hey Everyone,

I have an Optical Compressor on the way and would like to implement the Attack and Release mods, as well as the comp. level LED if possible. After spending a long while searching through the forums, all the older posts about this that I can find give me a 404 error when I click the links (for example- https://buildyourownclone.com/board/viewtopic.php?f=19&t=21293 and https://buildyourownclone.com/board/viewtopic.php?p=161039#p161039). Does anyone here have an archived version of these posts, or any more information they can offer?

Also, I will be using this as a bass pedal exclusively. Any suggestions on modifications to that end are welcomed as well.


Thank you in advance; I appreciate the help this forum provides

_________________
"It’s your soldering."

If you ever run into dead links on the forum, just replace 'buildyourownclone' with 'byocelectronics' in the URL, as Stephen did above.

_________________
Scott

My band, Austin Hollow

Ah-

Thank you, gentlemen. I never put that together.


Appreciate the help

One more question for the hive mind here:

Want are the chances of adding a Blend knob to this effect? From what I can see through the search function there isn't much information about it, but I might just be searching poorly...


Thanks!

I am far from an expert, but my sense is that it would be tricky. I think you'd have to split the dry signal and the wet signal and then also add a buffer to drive the dry signal maybe? I seem to remember reading about it, but I have no idea where, so take it with a grain of salt. Keith or someone with more knowledge of compressors and blend controls may chime in with a clarification or correction.

The BYOC 5-Knob Compressor has a blend control (called Ratio), but it's based on the Ross comp, which is a lot less transparent than the optical compressor. And anyway, it's out of stock at the moment. But if you like poking around in the technology, you could take a look at the schematic and see what you can learn.

_________________
Scott

My band, Austin Hollow

The envelope trigger and full wave rectifier are just too simple to add "attack" and "release" to the optical compressor circuit. You would need to add an extra transistor at the very least ala the Envelope filter. Unfortunately, we didn't assign number designators to the components on the envelope filter schematic, but you can see where the attack pot is. And replacing that 150k resistor with a pot will give you a "release".

Adding a "compression light" is pretty easy. Just add an LED in series with the LED of the optocoupler. You'll probably need to reduce the 4k7 limiting resistor to 3k3 so that both LEDs are bright enough.

Adding a blend will also require additional circuitry. It's probably best to look at the Mimosa and compare that with the original orange squeezer to see how that's done.

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Thanks, guys.

Sorry for the delay, Keith. I just saw that you had responded.

Maybe I was vague in the attack / release mods desired. Following along with this (http://www.byocelectronics.com/board/viewtopic.php?f=19&t=17982) thread, it seems like what Coolhand suggests in his 3rd post would be great : the addition of a 3 way switch to vary Attack rates. I already have the supplies to do so, as well as those to add the Release knob mentioned. In theory an Attack pot would be cool, but the switch seems like it will work well enough. And I guess I could socket those caps and further play around with values using those listed in the linked post as a starting place if I needed to get all OCD about it.

Regarding the LED addition, as I understood the from posts in the thread this could only be done with a 5-leg optocoupler. My kit came with the 4-leg version, so I had assumed I would have to replace that component to complete this mod. If I do need to replace this, would this one (http://smallbear-electronics.mybigcomme ... -vtl5c4-2/) work? I can't seem to find much of a selection across the web.

And as to the Blend knob, I'm afraid your suggestion is a little over my skill set, Keith (though the idea is appreciated). I'm afraid I can't read a circuit diagram to interpret where I should make those breaks. I'm a machinist who went to school for ME, and am now starting to wish I had paid a lot more attention to those EE electives I was required to take...

Thanks for all the help everyone. Beyond the satisfaction of building the effects myself, part of what makes all this so interesting is the ability to add things here or there to make them exactly as wanted. I am now on a quest to rid my board of all non-BYOC effects (well, I guess the Loop Station can stay...) and am grateful that this board exists. For folks like me with more enthusiasm than EE experience, the ability to learn from a larger collective is a great thing.


Thanks again and Happy Holidays

Yes, adding a toggle to switch between caps is an easy way to get some control over the attack time....and honestly...all you really need is fast or slow. That parameter is so incredibly subtle, that the fine tuning abilities of a pot are a waste.

If my understanding of a "compression LED" is an external LED that lights up brighter as it compresses harder, than what I described is correct. You do not need a different opto-coupler, nor would you want to use one.

An opto-coupler is an LED on one end and a light dependent resistor on the other end. If you could see what was going on inside the hermetically sealed capsule, you'd see the LED lights up brighter as it compresses harder. So you already have a "compression LED"....you just can see it because it's encapsulated.

If you pull the positive leg of the optocoupler, connect that to the negative leg of another LED, and then connect the positive leg of the new LED to the positive eyelet on the PCB, this would be called "adding another LED in series". It would react the same as the encapsulated LED, only you'd be able to see it. And it probably wouldn't be quite as bright, so you'd want to reduce that 4k7 limiting resistor to 3k3 or 2k2 to compensate.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Thanks Keith.

Yes, that is what I meant about the LED. That is a good explanation; it makes more sense than what I had inferred following the thread (and the 4 vs. 5 leg optos). Space-wise, it seems like I would have to mount the optocoupler on the 'back' side (solder side) of the board in order to get the legs of the component and the LED to reach each other as well as the enclosure top. I'll see what I can do to mark things up and drill a bezel hole in what seems like a good spot.

Thanks for the advice

I'm not 100% certain what you are trying to do, but I don't think you need to remount the optocoupler. It seems like you are trying to bring the garage to the car rather than just backing the car into the garage. Just pull only the + leg of the optocoupler from the PCB (the leg with the yellow dot). Rather than relocating the optocoupler, simply run wire(s) to and from your external display LED to the optocoupler and PCB.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

But bringing the garage to the car is just so much more fun!

That's a good point, not sure why I didn't think of it - there is plenty of space to snake some wires around to the other side of the board. As to changing the resistor value - would this only change how bright the 'display' LED would be? Is there any drawback in the function of the optocoupler by doing this? Or is it just because there are now two 'visible' LEDs so the current needs to be higher as it is split between the two?

Thanks again as always

Technically, there will be two visible LEDs, but the second is your on/bypass LED and it has nothing to do with this. Consider it a completely separate circuit. You may need to adjust the value of the R10/4k7 resistor. This is a limiting resistor. It controls how bright the LED in the optocoupler gets (exactly the same as R13 controls how bright your on/bypass LED gets). Since you are adding another LED in series with the optocoupler LED, R10 will control the brightness of both. Adding another LED in series may affect the brightness, and therefor affect the compression. If you notice that the compression doesn't seem to get quite as strong as it did before, reduce the value of R10.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Aha! I had assumed you meant lowering the value of R13. That's why I was confused.

I left R10 open when I populated the PCB with plans to add the "Release" pot mod. I was going to use a B50k pot with a 1k resistor tied to one leg for this (I had assumed those pot + resistor values were suggested by Coolhand to place the values inline with the stock 4k7 R value).

In the original mod post I saw (using an older kit), the compression LED addition was based on the 5-leg octocoupler. Does this mean then that I should choose either the pot mod or the LED addition since I have the Rev 2.1 and 4-leg? Or just that I should be prepared to play around with the resistor values of what I tie to the pot leg?



Thanks for your patience in talking through all of this...

I don't know, man. You're confusing me. Now I'm not sure what you want to do. It sounds like you're under the impression that you can only do one or the other. Post a wiring diagram of what you want to do, and I'll proof it.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Ha Ha. Sorry Keith.

So here is an image of what I wanted to do. I want to add the Release pot mod as well as the Compression level LED mod. I just wasn't sure that they would work together as described in previous threads.


Thanks again

Yep. That's perfect. Just a few things to watch out for.

1. Make sure you have your new LED oriented correctly. Connect the shorter cathode lead to the optocoupler. Connect the longer anode lead to the square eyelet on the PCB.
2. I think you have your B50k pot wired backwards. I think you should move the 1k resistor to the other side. Lower resistance = more compression. Turning it clockwise will give you less compression wired that way....I think.

One last thing. The knobs on compressors are famously misnomered....and understandably so. The parameters are so incredibly subtle, that they can be hard to describe. "Attack" on most guitar compressors is really release. "Sustain" is really sensitivity (which is the case here). This pot you are adding is definitely not a "release" knob. If anything, I would probably call it "ratio" or "compression".

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Wonderful.

The extra explanation is great; that clears up some things I had always wondered about. So then, in reality, what would you call the 'Attack" mod (with the SPDT switch and the additional caps)? I swear, this is my last question!


Thank you again for all of the guidance

That one really is "attack". Compression increases as the LED inside the optocoupler gets brighter. Q1 and Q2 act in parallel as a sort of switch to ground that turns the optocoupler LED on and off. As the envelope trigger receives signal, Q1 and Q2 open up and complete the LED circuit to ground. The higher the signal level, the more Q1 and 2 open up and the brighter the LED gets. But before current can flow to ground from +v, through the LED, through R10, and ultimately through Q1/2, it must first fill the C6 capacitor to its full capacitance. So if any of what I just wrote makes sense, you can see how the larger the capacitance of C6 is, the longer it will take between the time you pluck the string and the time compression begins. If it doesn't make sense, just know that the larger C6 is, the slower the attack. The smaller the C6 is, the faster the attack. So that mod is an actual true "attack" mod. You may not be able to adjust it like you can with a potentiometer, but this mod doesn't require any extra circuitry and as I said before, attack on a compressor is so subtle and so sort (only a few ms) that a switch with "short", "medium", and "long" is plenty. It's not like an envelope filter where you want an adjustable range of attack between 100 ms to a whole second or two.

Please feel free to ask any other questions you have. That's what the forum is here for.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

That does make sense, and gives me a much better idea of how the circuit functions.


Thanks again for helping me to learn more about all this...

So-

While waiting for some LED bezels to arrive and also waiting to have some free time after work I had a thought...

Would it make any sense to add a switch in line with the 'compression level' LED? I'd like to have that indicator visible for times when I am setting and adjusting the pedal, but I imagine there will be long periods of time in between changing things where the on/off LED will be enough. Could I just put something like a SPDT toggle switch (or a latching push button) in between the board and the LED as drawn above? Or would this adversely effect things in a way that I haven't thought of?


Thanks!

Sorry. I'm not totally following what you're trying to do. You want to be able to turn the compression level LED on and off? A diagram of what you want to do would be better.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Yeah, exactly.

I'll try and modify the image I posted above in the thread, but yes. Just a switch to turn the 'level' LED on and off...

Something like this:

I guess if you want to do that, you can. I'm not really sure what practical purpose that would serve though.

You'd need to use a DPDT toggle switch though. You'd need to "bypass" the LED, not just "make or break" to turn it on and off, because you still need to connect the LED inside the optocoupler to +v.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com