This is astounding. Every other tutorial I've found for VCAs uses two op amps and a lot of it goes over my head, but this is exactly what I've been looking for
Okay.. baked my first two led+ldr fimo encased optocouplers a few days ago, fried it all together to 2 VCA's and... well it works like a charm :D exciting haha
a small tip - just use heat shrink tubes to make vactrols. Simply cut ~15mm of the tube, on one side insert LED, on the other - photo resistor. Apply some heat with soldering iron and all good. Super cheap and 100% effective.
6 лет назад+1
Yep. I don’t think I mentioned heat shrink but I did try that aswell. The tubing I had at hand wasn’t large enough though so I couldn’t get it around the led, that is why. But doesn’t heat shrink let some light through? I’m thinking it is really thin...
Kristian Blåsol well I guess it depends of the brand, maybe some are really thin. but if you’re using black - it totally should be fine. I’ve made a few in this way - no visual light coming in / out and works just fine
Audio is the only area where commercial use of these photoresistors are allowed in the EU (if they are Cadmium based). The tremolo effect on "How Soon is Now" by the Smiths is possible via vactrols due to the high voltage capability of photoresistors and the high voltages involved in tube preamps for guitars.
I make mine with the shrink plastic that you use on wires with a heat gun and that shrinks up and closes it up really well and it also insulates it electrically. I do a small piece of it around the ends of the LED and the photo resistor and then I do it again with a larger one around that and that's sufficient
Kristian: Module (all) in a week. Me: Module (1) in a year plus counting.
4 года назад+1
Well I have slowed down now aswell. Now it is more like 1module/2weeks. But the gist of it is still there. And I’m just trying to inspire you to speed up just a wee bit. ;)
First of all I'm enjoying this series a lot so thanks for the great job! When the "Vactrol" was mentioned on the previous video I immediately thought "Why not using an optocoupler?" And it is an optocoupler indeed xD I've used 6N137 (DIP8) format and later more effective H11L1 (DIP6) optocoupler chips to make MIDI gear. They're not expensive at all. Cheers!
You probably know this already, but for anyone else browsing these comments, the chips you mentioned won't work for this application as they are logic-level output (5V/0V only), so you won't get the smooth analog signal that a vactrol outputs.
Lol, strangely this doesn't work at all... I used some standard clear casing LEDs, some standard photoresistors and the VCA closes so slow after triggering it it's just ridiculous. As if the light emitted by the LED is decaying for more than 20 sec. or so... which was not the case when I checked the LED with a battery before buildung the vactrols, it was shutting off immediately then. And the photo resistor wasn't that slow either, when I checked it with the resistance measuring part of my multimeter. I just don't understand what I'm doing wrong. I've built so many kits, built my own synths and sequencers with 40xx CMOS chips, PICaxe and the like but with this modular stuff is the first time I'm really stumped and not able to find out whats wrong... :D
Hey hey, your modular vids are very very helpful thank you so much for all this. A problem i came acoss with vactrols like that was mostly the lack of over voltage protection. I designed them for 5v gates and after i broke it i realalised that befaco muxclicer for exampel outputs more than 10v gates. Turning it into an active module to give the led a fixed supply and switch it with a N-Mosfet could work. A friend just gave me that tip. Havent tried yet but should work. Maybe you have an idea for passive protection for 0hp stuff. But i think if you only use your diy cvs you know your V levels. Anyway awesome vids bro !!!
5 лет назад+1
That is an interesting idea your friend gave you, that we almost need to ponder more upon :) I added a potentiometer to my Vactrols as shown in the video, and I always turn them down quite far before I connect anything, that way I dont send too much voltage into the LED... But the MOSFET thought might have something to it. If you try it out let me know! As for my DIY CVs I have no idea what they signal they put out. I think they are very different every one, which gives them their own characteristic ;)
HINT for HOTGLUE!: if you use hotglue and the vactrol doesnt work just use IPA to "degrade" the Hotglue and recover your LED and LDR. The IPA dissolves the "glue"-Component of the Hotglue and make it brittle so you can take it appart again ;)
4 года назад+1
Thanks for the tip. I hope we are not talking about “India pale ale (IPA)” beer? That would be wasting a good beer... 😉 I’ll research what this might be in Swedish so I know what to buy :)
@ IPA är Isopropanol, finns hos Kjelle. www.kjell.com/se/produkter/hem-kontor-fritid/kontorstillbehor/kemi-spray-lim/spray-olja-isopropanol/prf-ipa-elektronikrengorare-p18370.
What do you think about adding a half wave rectifying diode in series with the LED and CV in to protect the LED from reverse voltage damage?
3 года назад
That might be an idea. I haven’t thought about it but yeah. You mean in parallel though right? And going the other way for reverse protection? Hard to visualize without a schematics. :)
could baking at 110 deg damage the components? The LED I'm planning to use is rated for storage up to 100 deg celsius and the GL5516 has an operational range up to 70 deg.
Wow, I forgot to put a resistor on there, and for some strange reason it did not work. I hooked the LFO up to a LED, and with the 10K it was on all the time, so I guess this wiould be hard without a pot, but I just can't seem to understand how to wire up a pot without a stripboard layout. I will order some LDR's before I play more with this, because I think all the vactrols I burnt are pretty expensive.
4 года назад
Yeah vactrols are expensive. Making your own is “good enough” and Munich cheaper. :) you need the resistor to lint the current to the led otherwise the led breaks at such high voltages.
You probably could do it, but since they are phototransistors rather than LDRs the output would be either on or off at your supply voltage, so you wouldn't be able to use (for example) a triangle wave to control it.
What do you think about the LiteOn LTV817? Could that work? It’s a
5 лет назад+1
Haven’t thought about using optocoupler a for this. They are on off though. So no nuance in throughput. Also most optocoupler are 3.3v so keep that in mind. Try it and let me now....
Kristian Blåsol good point. Can’t believe i missed that. I came across them in some schematic for a cv control function. But I guess it’s used as an on/off there. I will order a few none the less. I will experiment if it can be used in a semi useful manner.
Kristian Blåsol thanks :) But I have questions about vactrols: The LDRs have a different characteristics and what the models of LDRs you use? And if you use vactrols in parallel with potentiometrs - characteristics of the LDRs are depended from impedance of the pots? And what you think about resistor before positive leg of LED in the vactrol (for voltage limiting)? P.S. Thanks in advance for your answer, and sorry please for my english... :-|
5 лет назад
I actually dont know which type I used. I just took what I had at home, but I know there are many different ones of LDRs take one with a high off resistance (1M+) and as low on resistance as possible. To get the best switching effect. How do you mean in parallell to the vactrol? Yes, some kind of resistor is needed in series with the LED to keep it from frying this is where I put my Potentiometer, to limit how much input signal affects the LDR...
hello i don't speak english very well. thanks for the tutorial and all :), i want to do this module and have a question. in the squematic only appears(?) the ground, where is the vcc or what? thanks
4 года назад+1
Hello, This is a "passive" component. No VCC is needed, as the Vactrol uses the voltage from the gate input to "open" the signal path between input and output. Hope that helps. Sorry for late reply...
Great tutorial. Just wondering if anyone has implemented this design into eurorack format? I want to build one, but I'm not sure if I should add a voltage regulator since the circuit require connections to + and ground and eurorack standard is 12v.
4 года назад+1
This is eurorack format. It uses 12V and gnd which both are present in the eurorack power strip. So it will work fine in a eurorack.
Ric Jenner just saw that I wrote 12vac. I of course meant 12v (as in dc) which is the eurorack standard. Sorry if that was confusing. I have fedited the answer to reflect this more correct info. (I of course blame auto correct. 😉)
@ Wow, i think it depends on how many you need and your resources. If just building one or two circuits maybe buy them? Building 50 circuits, build them. Or get lucky like i did and buy a bulk bag of vactrols.
This is astounding. Every other tutorial I've found for VCAs uses two op amps and a lot of it goes over my head, but this is exactly what I've been looking for
Okay.. baked my first two led+ldr fimo encased optocouplers a few days ago, fried it all together to 2 VCA's and... well it works like a charm :D exciting haha
a small tip - just use heat shrink tubes to make vactrols. Simply cut ~15mm of the tube, on one side insert LED, on the other - photo resistor. Apply some heat with soldering iron and all good. Super cheap and 100% effective.
Yep. I don’t think I mentioned heat shrink but I did try that aswell. The tubing I had at hand wasn’t large enough though so I couldn’t get it around the led, that is why. But doesn’t heat shrink let some light through? I’m thinking it is really thin...
Kristian Blåsol well I guess it depends of the brand, maybe some are really thin. but if you’re using black - it totally should be fine.
I’ve made a few in this way - no visual light coming in / out and works just fine
Sugru would work instead of Fimo putty. Available at Clas Ohlson in Sweden or easily available from the sugru website.
Stephen Cook Yes sugru would work too. But it is much more expensive than Fimo clay and won’t last as long just lying around. 😉
@ anyway, just paint it or something if its transparent
Heat Shrink my dude and a heat gun or hair drier 10:20 and there is air drying fimo and other lighter types.
Audio is the only area where commercial use of these photoresistors are allowed in the EU (if they are Cadmium based). The tremolo effect on "How Soon is Now" by the Smiths is possible via vactrols due to the high voltage capability of photoresistors and the high voltages involved in tube preamps for guitars.
Technically your Vactrols are Voltage Controlled Attenuators, as there is no amplification happening. But simple and useful :-)
Keep on going ;-)
Thanks for clearing it up..
To be fair, most VCA’s are voltage controlled attenuators.
Isn't that what VCA stands for?
The A in VCA usually stands for amplifier. This circuit doesn’t amplify. It only attenuates. It only lowers the signal strength it doesn’t raise it.
@@PWMaarten Most VCAs are set up for unity gain at max CV. They don't have to be, though. I've built some that have some gain (X2 usually).
I make mine with the shrink plastic that you use on wires with a heat gun and that shrinks up and closes it up really well and it also insulates it electrically. I do a small piece of it around the ends of the LED and the photo resistor and then I do it again with a larger one around that and that's sufficient
I recommend limiting resistors on the vactrol’s LED. Without them you could fry the LED.
Kristian: Module (all) in a week.
Me: Module (1) in a year plus counting.
Well I have slowed down now aswell. Now it is more like 1module/2weeks. But the gist of it is still there. And I’m just trying to inspire you to speed up just a wee bit. ;)
First of all I'm enjoying this series a lot so thanks for the great job! When the "Vactrol" was mentioned on the previous video I immediately thought "Why not using an optocoupler?" And it is an optocoupler indeed xD I've used 6N137 (DIP8) format and later more effective H11L1 (DIP6) optocoupler chips to make MIDI gear. They're not expensive at all. Cheers!
You probably know this already, but for anyone else browsing these comments, the chips you mentioned won't work for this application as they are logic-level output (5V/0V only), so you won't get the smooth analog signal that a vactrol outputs.
@@bocoroth915 you are totally right :) Later after writing the OG comment I learned that. Thanks for pointing out!
Lol, strangely this doesn't work at all... I used some standard clear casing LEDs, some standard photoresistors and the VCA closes so slow after triggering it it's just ridiculous. As if the light emitted by the LED is decaying for more than 20 sec. or so... which was not the case when I checked the LED with a battery before buildung the vactrols, it was shutting off immediately then. And the photo resistor wasn't that slow either, when I checked it with the resistance measuring part of my multimeter. I just don't understand what I'm doing wrong. I've built so many kits, built my own synths and sequencers with 40xx CMOS chips, PICaxe and the like but with this modular stuff is the first time I'm really stumped and not able to find out whats wrong... :D
It's likely the photocall. They are all fairly different in their response. Especially the timing. Good vactrols are specd on timing.
Excellent explanation sir 🙏
Hey hey, your modular vids are very very helpful thank you so much for all this. A problem i came acoss with vactrols like that was mostly the lack of over voltage protection. I designed them for 5v gates and after i broke it i realalised that befaco muxclicer for exampel outputs more than 10v gates. Turning it into an active module to give the led a fixed supply and switch it with a N-Mosfet could work. A friend just gave me that tip. Havent tried yet but should work. Maybe you have an idea for passive protection for 0hp stuff. But i think if you only use your diy cvs you know your V levels. Anyway awesome vids bro !!!
That is an interesting idea your friend gave you, that we almost need to ponder more upon :) I added a potentiometer to my Vactrols as shown in the video, and I always turn them down quite far before I connect anything, that way I dont send too much voltage into the LED... But the MOSFET thought might have something to it. If you try it out let me know! As for my DIY CVs I have no idea what they signal they put out. I think they are very different every one, which gives them their own characteristic ;)
I will let you know ;)
HINT for HOTGLUE!: if you use hotglue and the vactrol doesnt work just use IPA to "degrade" the Hotglue and recover your LED and LDR. The IPA dissolves the "glue"-Component of the Hotglue and make it brittle so you can take it appart again ;)
Thanks for the tip. I hope we are not talking about “India pale ale (IPA)” beer? That would be wasting a good beer... 😉 I’ll research what this might be in Swedish so I know what to buy :)
@ IPA är Isopropanol, finns hos Kjelle. www.kjell.com/se/produkter/hem-kontor-fritid/kontorstillbehor/kemi-spray-lim/spray-olja-isopropanol/prf-ipa-elektronikrengorare-p18370.
Hi! Great. Any link for the clay in Sweden? Panduro?
Yes. Panduro has both Cernit and Fimo i think. Penstore, skapamer.se and slojd-detaljer.se should have it aswell.
What do you think about adding a half wave rectifying diode in series with the LED and CV in to protect the LED from reverse voltage damage?
That might be an idea. I haven’t thought about it but yeah. You mean in parallel though right? And going the other way for reverse protection? Hard to visualize without a schematics. :)
could baking at 110 deg damage the components? The LED I'm planning to use is rated for storage up to 100 deg celsius and the GL5516 has an operational range up to 70 deg.
See the comments above re using heat shrink tubing.
Wow, I forgot to put a resistor on there, and for some strange reason it did not work. I hooked the LFO up to a LED, and with the 10K it was on all the time, so I guess this wiould be hard without a pot, but I just can't seem to understand how to wire up a pot without a stripboard layout. I will order some LDR's before I play more with this, because I think all the vactrols I burnt are pretty expensive.
Yeah vactrols are expensive. Making your own is “good enough” and Munich cheaper. :) you need the resistor to lint the current to the led otherwise the led breaks at such high voltages.
Hey Kristian, ever tried to do a VCA with PC817 or 4N25 optocouplers?
You probably could do it, but since they are phototransistors rather than LDRs the output would be either on or off at your supply voltage, so you wouldn't be able to use (for example) a triangle wave to control it.
What do you think about the LiteOn LTV817? Could that work?
It’s a
Haven’t thought about using optocoupler a for this. They are on off though. So no nuance in throughput. Also most optocoupler are 3.3v so keep that in mind. Try it and let me now....
Kristian Blåsol good point. Can’t believe i missed that.
I came across them in some schematic for a cv control function. But I guess it’s used as an on/off there.
I will order a few none the less. I will experiment if it can be used in a semi useful manner.
Thank you very mutch for good tutorial :)
Your welcome. :) and thanks for watching.
Kristian Blåsol thanks :)
But I have questions about vactrols:
The LDRs have a different characteristics and what the models of LDRs you use?
And if you use vactrols in parallel with potentiometrs - characteristics of the LDRs are depended from impedance of the pots?
And what you think about resistor before positive leg of LED in the vactrol (for voltage limiting)?
P.S. Thanks in advance for your answer, and sorry please for my english...
:-|
I actually dont know which type I used. I just took what I had at home, but I know there are many different ones of LDRs take one with a high off resistance (1M+) and as low on resistance as possible. To get the best switching effect. How do you mean in parallell to the vactrol? Yes, some kind of resistor is needed in series with the LED to keep it from frying this is where I put my Potentiometer, to limit how much input signal affects the LDR...
hello i don't speak english very well.
thanks for the tutorial and all :), i want to do this module and have a question. in the squematic only appears(?) the ground, where is the vcc or what?
thanks
Hello, This is a "passive" component. No VCC is needed, as the Vactrol uses the voltage from the gate input to "open" the signal path between input and output. Hope that helps. Sorry for late reply...
fy fan vad bra! my swedish still sucks after years of living here. vart bor du?
South. Near Hässleholm if you know where that is. :)
Kristian, is it possible to build ground loop isolators with vactrols??
I would say no on this. I still don’t fully understand ground problems... :/
Yes, definitely. One of the best thing about Vactrols, total isolation.
Great tutorial. Just wondering if anyone has implemented this design into eurorack format? I want to build one, but I'm not sure if I should add a voltage regulator since the circuit require connections to + and ground and eurorack standard is 12v.
This is eurorack format. It uses 12V and gnd which both are present in the eurorack power strip. So it will work fine in a eurorack.
@ I see, thanks for the response.
Ric Jenner just saw that I wrote 12vac. I of course meant 12v (as in dc) which is the eurorack standard. Sorry if that was confusing. I have fedited the answer to reflect this more correct info. (I of course blame auto correct. 😉)
what's wrong with an off the shelf opto-isolator?
Nothing. Except the price for one where I live. 4$! 😅
If you mean the ones you can find in DC power supplies they are usually digital output (on/off) rather than analog.
An optoisolator is not necessarily a vactrol. There are many digital optoisolators, just on or off.
@ Wow, i think it depends on how many you need and your resources. If just building one or two circuits maybe buy them? Building 50 circuits, build them. Or get lucky like i did and buy a bulk bag of vactrols.