Passive tremolo video. Let me know what you think?

[darron]

Maby I should have said " I changed the 22uf cap to 10 in order to make the rate knob more usable ( half of the sweep is way to slow to be usable) and I added 2 ldrs to get the depth I wanted " I stumbled upon some 2k-450k ldrs and I am using one of them now with an ultra bright Led. I am getting a slight tick because the voltage is changing too fast. They were older ldr's so my guess is the ultra bright leds were not out when they where made so I am going to experiment some more.

i agree that the slower sweeps are something i'd never use either, but i left it there for a more phaser sort of volume drops. if you changed to a 22uf cap and want to regain that really fast rate, then lower the 1.5k resistor. that was about the value that worked with my ldr and 50uf cap that allowed for the fastest possible trem with the ldr being able to keep up and not 'blur'. another idea would be to replace the 100k rate pot with a 50k and you'd get the same effect, or replace it with another 100k with a taper that leaves the really slow sweeps crammed right at one end, which is what i plan to experiment with. where  did you get that ldr? it sounds ideal.

as for the tick, being optically isolated it shouldn't come through. it would have to be either because you connected the ground to the negative power, or because it's leaking through somewhere by capacitance. if you have a shared power supply with other pedals then they probably connect the ground to the negative power also. i'll experiment with putting a cap on the power to see if it can smooth it out, but it would be better if it wasn't there at all. i hope it doesn't happen to me when i make my pcb. that rhymed.

thanks for your feedback (:

[ItZaLLgOOd]

I got mine to work.  Very nice. Just need to box it up. Thanks for the help.

[casey]

i keep getting a bandwidth limit being reached message...could someone email this schematic to me...? 

[darron]

i keep getting a bandwidth limit being reached message...could someone email this schematic to me...? 

sorry. after posting the video and the large pdf files everyone used my 1GB of webspace this month, which should refresh soon. i just put a temporary copy here:
http://members.optushome.com.au/bluespherecreations/forum/optical-tremolo.pdf

i don't like the idea of emailing files around since i update them so often. hopefully the original link will work again soon.

good luck with it. i'm really pleased that other people are getting good results.

[darron]

i know that people are going to want to be able to run any effect with the same power supply and shared ground to negative, i want to also! i've read with a lot of tremolos you should be weary of the tiny click as the wave changes direction. anybody have any ideas of how to get rid of this so that i can use one power supply? that would be nice (:

darron

edit: the geofex voltage multiplier causes a similar problem, if that stirs any ideas. otherwise ill be happy to keep this one running on battery.

[ItZaLLgOOd]

I got the tick on the breadboard but I was sharing the power ground as mentioned before.  I was able to fix it on the board but what about when I try to box it up?  I usually use a stereo jack and use the ring for the power ground and the sleeve for the rest.  Will this be enough to keep the tick out??

[darron]

I got the tick on the breadboard but I was sharing the power ground as mentioned before.  I was able to fix it on the board but what about when I try to box it up?  I usually use a stereo jack and use the ring for the power ground and the sleeve for the rest.  Will this be enough to keep the tick out??

the ideal thing would be to just use two mono jacks. when i box mine up i'm going to get the bypass switch to just hook up the signal and hook up the power directly from the battery at the same time. this circuit won't need to be powered in standby mode because it doesn't have any opamps etc. that need to be running before the audio gets hooked up to it. so the power doesn't end up contacting with the jacks, or the enclosure. i'm waiting for my new Lucibox for this one I think

[Albot]

Wow gotta build this one. 
Tried to make a layout for PCB with very slow progress (I'm kinda new to this).
If anyone got a finished one please post it here if not I'll post mine when it's done.

I love that you don't need any transistors of any kind

[Albot]

The wave switch got a bit messy with the offboard resistors and I made the pulse trim into a pot, other then that i think it might acctualy, maybe, and with a bit of luck work. 

My first layout!
Does it look like it might acctualy work?  Im gonna try and build it if you guys give thubs up.

[darron]

The wave switch got a bit messy with the offboard resistors and I made the pulse trim into a pot, other then that i think it might acctualy, maybe, and with a bit of luck work. 

My first layout!
Does it look like it might acctualy work?  Im gonna try and build it if you guys give thubs up.

that LOOKS cool. i'll take a better look over it tonight as i'm about to leave for work. the pulse pot is something that i really don't think you'll want as an actual pot, as most of it's range is unusable. i. did it as a trim pot. i think the rate pot would work better if you wired it the other way around. lower resistance makes a faster trem. same with the depth pot, lower resistance lets the LEDs go brighter and makes the tremolo deeper. it wouldn't matter, but i just think turning a pot clockwise should increase things. i might have looked at it backwards and got it wrong though :S

i may also have drawn it wrongly on the schematic as i can't remember ever thinking about it before.


here's one that I was working on for PCB. i haven't built it yet. i never intended to release it as i do things a bit differently. there's a large gap between the switch and the electronics because that's where the audio jacks would fit perfectly in the enclosure. i eliminated the wave switch though:


i didn't post that layout as a recommendation that you build it, clearly Albot's layout looks like it will be neater (I don't like that pulse as a pot though). But it gives you something else to look at.





HERE ARE SOME MODS

1)   to get rid of any clicking noise in the power (even if you don't ground it), put a 10uF NP cap between pin 7 and ground. pin 7 is top right, then down one. doing this you could probably even use the stereo jack trick and ground the circuit.


2)  to get any more 'wave' control, you can vary one of the 47k resistors going to pin 6 slightly higher or lower.



i'll reflect these on the schematic soon. thanks for bringing this topic back up (:


with that pcb layout Albot, make sure you get a ldr which has VERY low resistance as you won't be able to use two in series. also, put in a very bright green LED.

thanks! (:

[Albot]

Alright! your comments makes me all fuzzy inside (no pun intended).
Ah, great. I'll see what i can do to fit a pulse trimpot instead. might have to jumper it.. dunno

About the backwards pots I'm sure i did it wrong. I usually don't pay much attention to what directions they're wired up since i always have to fix some things after i know if the effect works or not. I'll redo the layout and make them right though. don't want to confuse anyone.. and some series holes for the ldr's

[darron]

Alright! your comments makes me all fuzzy inside (no pun intended).
Ah, great. I'll see what i can do to fit a pulse trimpot instead. might have to jumper it.. dunno

About the backwards pots I'm sure i did it wrong. I usually don't pay much attention to what directions they're wired up since i always have to fix some things after i know if the effect works or not. I'll redo the layout and make them right though. don't want to confuse anyone.. and some series holes for the ldr's

series led/ldr would be cool on a layout for other people. i like the idea of getting it right with just the one combo though. thanks, that would be really good to have a layout ready that everyone can use. i'm not sure if log/lin pots are better as i just used trim pots for now. i might start looking into making the pulse control more of a pot and make it smaller with a series resistor so that it's all usable.

i just re-uploaded the schematic with the 10uf cap to get rid of some clicking. could you please find room for that also. it will fit on your layout really easily. make the cap jump the trace (:

Albot, I just noticed all of the ground pads and that the LDR goes to them also. I tried to avoid grounding the negative so that the circuit is completely isolated from the signal. That would definitely let click through without that experimental 10uf NP cap I was recently experimenting with, but that might have fixed it now.


i was supposed to leave for work 1 hour ago! i got too caught up.

thanks heaps Albot

[Albot]

This should be right. I hope.
You can just cut or edit the traces depending on how you want to match the ldr/ldrs and led/leds. I could send the project file or send any special requests as pictures regarding that part.

Other then that i should be ok. I got a bit puzzled about how you hooked up the in/output but if others got it working this way it probably should work (I'm a complete novise so don't take it as any criticism I simply don't understaind how it could work  ).

Hmm.
This is my first design (well now it's reworked so it's kinda my second) so if you spot something wrong with it im just happy if you comment.




Hah, now it's not so clean anymore.
I'm gonna try it sometime in the week and come back to verify if it works.

[foxfire]

i finally got to put one together and it's pretty damn cool. i built an EA trem and love it but, it is all but lost in front of an amps distortion. not this little guy. sure it looses some of it's edge but, nothing like the EA trem. i did the wave switch mod and it's definitely worth it. the only real part change i made was using a nsl-32 optocoupler. i got a bit more "effect" with it than i got from my homemade led/ldr combo. i used an audio pot for the depth control and a linear for the rate. i think both want to be linear. thanks for sharing Darron.

[darron]

Albot, could you use C2 as an actual jumper? maybe use a cap with a wider foot print? if you want to make the layout a little bit cleaner, then you can take R3 off the switch, and move it in series with D1 on the board.        R3 and the depth pot both make up one resistance, so it won't matter which order you put them in. Get what I mean? R3 should be 300 ohms, not 300Kohm. it's just to lessen the current to the LEDs a very tiny bit.

the in/out are hooked up right. this signal doesn't go 'through' anything. the signal at input and output are exactly the same. the circuit just takes a small part of the signal through the LDR and connects it to ground. anything that you connect to ground has the effect of muting the signal, so as the LED flashes it just controls how much the LDR connects and mutes the signal. could you please label D2 as 5mm high-intensity green? all looks really cool so far (:


when you build it, make sure that the LDR is in pitch black (as much as practical) except for any light coming from the LED(s) this should be okay just on the board i suppose once it's in an enclosure, but it would be hard to tune the trimpot since you'd have to close it up all the time to check lol.

[Albot]

Now it's neater and got some better cable connections imo.
I just updated the latest pics so theyr'e above.

Shold be pretty easy to fit any (most at least) trimpot in there now too.

I should put some kind if credit for you on it incase it travels the net and stuff.
What would you like to be called?

[Albot]

Here's a smaller version but more cramped leds/ldrs
The placement for the signal ground kinda buggs me but what the hell.

[Thomeeque]

Hi!

I have not read all comments here, so maybe I'm saying something already said: did you consider to put input resistor there, to make it "more" voltage-divider? Without this resistor will be behavior of your effect (mainly depth) strongly dependent on source output characteristics (output impedance). Value should be something like 4.7-10kOhms (?), this could be switchable on/off or pot could be used (like "Depth2")..

T.

[darron]

Hi!

I have not read all comments here, so maybe I'm saying something already said: did you consider to put input resistor there, to make it "more" voltage-divider? Without this resistor will be behavior of your effect (mainly depth) strongly dependent on source output characteristics (output impedance). Value should be something like 4.7-10kOhms (?), this could be switchable on/off or pot could be used (like "Depth2")..

T.

Hey Thomeeque. Yeah, you're thinking right. I tried putting resistors in series with the signal, but they didn't really help much. What your talking about with the depth being dependant on the output is right, which is why this tremolo won't work with say a keyboard. This is why I've been asking people how they found it to work with a buffer before/after. Nobody has responded yet but I've heard good things otherwise. This is a REALLY simple circuit. Ideally, it would be BEST if there were two LEDs shining out of phase to adjust one series and one going to ground. This would make a much better voltage divider. That's what I'm working on at the moment and is why I haven't really done a big job releasing a PCB layout or anything as I'm hoping to have a second version soon. With a proper voltage divider, factors like the LDR/LED won't matter as much either.

For such a simple circuit there's a lot to rely on to get it as good as it was in design. This sort of reminds me of the Fuzz Face....

[foxfire]

i tried oe of AMZ's basic jfet buffers in front and behind the trem and, the trem ticked in both places. with the buffer in front it lessened the trem effect and ticked. and with the trem in front of the buffer it increased the trem's effect, almost too much though. it all but cut the signal to a mute and, rendered most of the depth pot useless and it ticked. i wired the buffer and trem so that they shared the battery so i'm guessing thats why it ticked. i'm out of battery clips.