I made one to be a Bastl Kastle friend. Immediately great, thanks for the tutorial!

man you are great,gonna watch all of these videos

Well, I was going to make my first Atari punk console this weekend, but you just changed my plans..lol..thanks for sharing your knowledge mate!

hey o7, wanted to thank you for this vid......VERY MUCH!! i'm getting into building basic oscillators and noise circuits, and this circuit is so so legit, FUN and easy to make. I have been putting it on the output of everything lately and using the bastl cv trinity to send the vactrol rhythmic lfo's and envelopes. it works perfectly and sounds so soft, plinkety and analog. with a little fiddling with different leds and resistors it was pretty easy to get the cv voltage from trinity knob range, scaled to match the vactrol volume range. i really appreciate this revelation, because i really wanted some kind of simple envelope to tame and make useful the constantly ringing oscillator swarms...lol and this comes with an added bonus of lowpass filter too which has a very natural sound and can take the buzzing edge off the diy square wave oscillators. the trinity can send exponential shaped envelope cv, and this circuit responds well, making it really nice for shaping the constant input into sweet percussion sounds. but anyway, thanks again. would love to see more vids like this. (maybe the simple transistor ring modulator/waveshaper/bipolar vca one. it's passive too and uses one transistor and three jacks.) anyone considering trying this, SHOULD! : ) this vactrol is extremely useful and has made hours of experimenting with basic circuits pay off, because suddenly it has all become very controllable, musically useful and is really inspiring to use this circuit to perform different types of controlling. 🙋🏻🎛🎛🎛🐛

Thank you very much :-) With your help I made my first passive low pass gate and it sounds pretty much the same as my Meng QI DPLPG. I was a bit worried about the DIY vactrol but it works :-) cheers andy

another amazing video! the score and the gentle reverb on the voice audio are really great, too

love the reverb and the synth chirps, makes the whole thing easier on the ears and less boring

Excellent video , and very well explained . I may give this a go sometime in future. :-)

Many thanks for a well produced, interesting and useful video. Having watched it I've been enjoying experimenting with various LDRs, LEDs and resistor values. I'm getting some very passable results so a few of these will find their way into my modular. The main thing I've struggled with is keeping all of the light out. It's amazing how sensitive the LDRs are to very low light levels. I'll get hold of some heat shrink - at the moment I'm using black insulation tape and the light does like to find its way in! Really good cheap additions to my synth though - thank you

Oh my gosh! I think I'm gonna get into DIY now haha. That sounds amazing, and doesn't look like it's too unmanageable. Thanks for the inspiration, subscribed! :-)

I ordered some mini PCBs for a design similar to this. I'm going to make my own vactrols tonight. Hopefully it works.

I stumbled upon an old article int the electronic magazine from the early 80s, where not the LEDs, but the 12V miniature incandescent bulbs were used. What's interesting, the author recommended to use a kind of diaphragm between the bulb and the LDR. It was a piece of cardboard, painted black, with a teeny-tiny hole in the centre, like in the ancient _camera obscura_ . The diameter of this hole had to be selected EXPERIMENTALLY for the best result. I wonder if it only makes sense with a bulb or...?

hat's pretty cool! i never knew that combining an LED with a photoresistor was called a vectrol! i used to do that for fun making vibratos on inverter oscillators :D

Really great video and the results are amazing.

omg thank you so much! my diy vca until now was just any transistor this sounds way better ;) but i've got a quite high volume drop

Just found your channel, good stuff! I'm trying to get into more hands on, DIY side of synths with zero previous experience, stressful but rewarding...

very cool mate! I did on one project last year

Just found a universe of great ideas. Liked and subbed of course 👍🎹🖐

Thanks' for posting.Very nice,easy device!Definitely has that "Buchla, plucky-sound".Love it! : )

Two questions you can perhaps answer: A) Why is it called a Low Pass Gate? I've never understood that really. B) What are the functional differences between an LPG and VCA? All my synth learnin has pretty much been east coast school. I'm trying to wrap my mind around west coast school, but just don't really understand some of the concepts. I can use them, mind you. I just don't really understand them, which makes it hard to design sounds deliberately rather than "discovering" them experimentally.

I have a vintage stereo that uses a few of these types of devices in the fm receiver signal section, mainly the multiplex board. Could a variable resistor be used to adjust for best performance.

Thanks man. Very helpful 👍

I like your explanation and effort to show people ..but i would like to here the difference of the original sound ...and the vactrol filtered sound so you can hear what it really does..i heard lot of sounds but could not see wjst the folter really does..sorry for critic ..

Hello and thanks for this. I love the sound of a LPG. I built this and it works great on my Pulsar 23 but I can't get it to work right with my Behringer MS-20 clone. I think the EG1 on an MS-20 is only 5V max so it doesn't drive the LED hard enough. Do you have any idea where I might look for info to get the vactrol values appropriate for the MS-20? TX.

bro thanks a lot can u adice a breadboard mine is very hard and breaks even precutted wires when i stck them in

A lil' off-topic. :) How to make music which can be heard in the background of this tutorial (starting @0:09)? I believe I also heard this kind of sparkling sounds on Kaitlyn Aurelia Smith recordings... Are here the vactrols involved?

Hi! Electronics beginner noob here. First off, thank you for a very useful and very well-explained tutorial. I was wondering, what if I were to add a potentiometer to attenuate the cv input. Would I be ok connecting the side pins to cv in signal and ground and the middle "viper" to the resistor -> led-ldr combo +. Maybe this is a stupid question but I'm only taking my first baby steps in this thing. Happy if you can help, anyway thanks again for the tutorial.

I'd like to try it with an industrial vactrol. Can someone give me advice about choosing between those on THONK? They are VTL5C from XVIVE. Can't put the link here

Really dope, going to try it! thanks :)

Does he say the resistor value? I could swear he does but haven’t been able to find it. Thanks for any help!

What is the best color LED to use for this?

if you send a gate signal in, will there be a slight decay curve like on other vactrol lpgs?

Thanks for this simple tutorial. just getting started and it's super clear. Do you know if it would work for adding CV inputs to a guitar effect? I'm trying to hack my Robert Keeley compressor, and turn it into a module. Thanks again!

Very nice work - what type of LDR did you use for this? Also, have you done any measurement regarding the amount of time lag you get in the response? How long does the gate stay open once the LED goes off etc?

Really useful video! How much is your CV range in volts? Especially max V? Thanks!

This video is great to explain a vactrol but I guess I really didn’t hear the effect of the low pass gate as much as I was hoping to. Still love your channel though.

09:04 BETHOVEN! :D

What VST I could use as modulation source?

I can not hear the difference with the filter and without so can not compair what the lpf really does..sorry

...mmm....I might well make both and filter the APC with the Vactrols..if I control it with a s&h rather than the envelope I should obtain some interesting rhythmic sounds..do you think it would work?

hi, thanks for the video. did you messure the resistance of the foto resistor when the led is on? i had only a green led... out comes 50kohm for the light resistor. wondering if and in which direction i have to adjust the capacitor...

Hi, Thanks for this video. I made a vactrol gate based on your video using a 40106 integrated circuit as the LFOr. I have a Korg SQ-1 and wondered if you know anything about how i'd go about using it to make gate patterns in a similar way to how you have used the CV out from the 0-coast as an LFO. I assumed I'd be able to get the Gate from the SQ-1 output and achieve my desired result but it's seemingly more complicated than that.

Nice video Quincas, thanks for sharing. How significant is the volume drop from input to output when your vactrol is fully open ? I like the idea of a passive device, but wasn't sure if a make-up gain stage would be beneficial, or not really necessary

Would it be worth it to use a pot in place of the resistor for fine tuning?

So why would one need another non controllable VCA if you can already control the CV/gate before it goes thru this vactrol? Wouldn't you need a potentiometer on the LDR?

Nice :) If this is #2 though, where is #1? Can't see it in your uploads.

Brilliant, subscribed. Does adding the capacitor in the output means that this LPG will not pass CV or DC?

Hey! I'm pretty much a noob at this but I've seen people putting the resistor AFTER the LED part of the vactrol, at the "cathode" end (as I understand, with any diode there's a Anode, the recieving end, and a Cathode, the blocking end). I always thought putting the resistor on the anode end made more sense, that's where power comes from. Do you know of any reason why some would put a resistor at the cathode end? Thanks for this great tutorial, I'm going to put it into practise soon and hopefully force 4 LPG's in 4HP (I'll be using a protoboard at the back of the panel haha)

Interesting video even corresponding to another DIY build.. The Erica Synth SWAMP, would you use DIY vactrols in this module?

The light-dependent resistor, does it not wear out over time? Or is its lifespan good?

By far the most superior vactrol video > thank you Bo$$. I'm using a 2.2v LED with the 0 coast contour, and it works great. Only thing is though there is no resistor needed, from the Contour output. If I use a 33k resistor it won't light at all, even a 1k it's dim. I thought contour would have a hotter output; after measuring it on a meter it came out around just under 3v. What's the voltage coming out of your contour output if you get chance to measure? Thanks again!

im just using the audio from two ic555 chips ...will I get the same seq sound? you mentioned the audio you have going in ...do you have a straight tone going in and your out put makes a sequenced sound?

Really dig your stuff Do you think you could do a vid on the cem3320?

I love it. It should change the result with the brightness of the led, so it basically changes with the resistor that we choose. How did u choose your res?

Please help, I am entirely new to this and I got some 3.5mm jacks to do this, but idk which legs are ground or signal. There’s 3 legs, is there a ground and pos/neg signal or is it just ground and two signal?

What if you wanted this in addition to a potentiometer?

Hi does it matter what the capacitor is? What did you go for?

What is the value you went with for the current limiting resistor?

really cool ! Is it a Passive Low Pass Gate or a just Passive Vactrol VCA ? What can be done (simply) to adjust the low pass part ? will changing the value of the capacitor or put a pot in series or parallel to it change the band pass ?

Fantastic video. I was wondering how to Implement the tone switch. Is it just adding a SPDT switch with a different resistant party or is it a Capacitor? Thanks

Thanks for the video! So what does this do exactly? I honestly couldn't hear something. I came searching for a low pass filter to make a foot stompbox drum out of a piezo disc and cut all frequencies sharply above about 70hz out of the signal to the mixer. Is this what i need :)?

amazing :)

yeahhh cool !!! but what do you say about powering this module? how to top up the bus board

Hi! But... that exactly LDR you are use? :)

imo, voltage for synth, vactrol for fx...

nice!

Would you be willing to explain how this can be transferred off the breadboard and onto a pcb into a module? Perhaps a dumb question since I’m very new to DIY

Synth Diy Guy, Add a 25K potentiometer between 10nF and the audio "path" : )

Why the 33k resistor? I thought current limiting resistors for leds are usually under 1k.

What if you patch a 5 volts offset (from the math section) to audio in of the vactrol gate, audio output to dynamics and contour to cv input ? It should turn this into a real lowpass gate for typical buchla bongo Amazing tutorial by the way :)

Whuuu! Scary music 😨😨😨

Some posts on that forum thread are saying "that's not a low-pass gate it's just an attenuator" but... the LDR part of the circuit at kzfaq.info/get/bejne/bqh_odmEttbTd40.html looks like a low-pass RC filter to me, is that right? Thanks for the video, it's really good!

Great informative video, however the reverb on the voice it makes it quite difficult to follow. For me, at least. It's like, I'm in a tight acoustics room and you speak to me from a cave. When it's music it's fine. But when it's speech you need to follow along, it gets quite distracting. Otherwise, great info, like I said.

something that controls your Vacuum🤣 ?