The Psychotenuse Tremolo... reverse sawtooth tremolo with very few parts

[moid]

First Raccoon: Whaddaya mean we put the wrong value resistor in R1? Duck_Arse is gonna go crazy at us; we only just got away with that last screw up - he's bound to see through our disguise this time!

Second Raccoon: Yeah I've no idea how we did it - putting a 15K where we should've put a 100K resistor! It makes no sense; we're always so careful with resistors...

First Raccoon: yeah because everyone knows racoons are colourblind, so we always use the DMM to check each resistor don't we?

Second Raccoon: I don't know how that went wrong; we have a system and all raccoons use the system, don't we? Raccoon three uses the DMM on the resistors and passes them to me, I solder them and you check the schematic! Foolproof! Only a fool could screw that up...

Raccoon number One and Two turn to face Raccoon Three

Raccoon Three: Errrrmmmm...

Raccoon One: You didn't use the DMM did you dum-dum?

Raccoon Three: Errr yes I did, mostly... sometimes... sorry fellas... I kept thinking about how girls love reverse sawtooth tremolo...

Raccoon Two: Quite understandable - those are very distracting thoughts, why I sometimes have them myself...

Raccoon One: I'm surrounded by knuckle heads! If we don't follow the system, then we don't get the reverse sawtooth tremolo, and if we don't get the reverse sawtooth tremolo then girls are right off the menu!

Raccoon Two and Three: Sorry boss

Raccoon One: OK well fix the damn circuit and let's see what happens!

sounds of welding, metal plates being hit repeatedly, geiger counters clicking and a Van Der Graaf generator powering up, someone loops the first line of The Special's "Man at C&A"

Raccoon Three: OOoohhh the lights are all flickery now!

Raccoon One: Great work team, now what do we tell Duck_Arse?

Raccoon Two: Maybe we should say we had a cold solder joint? That could happen to anyone, even pros get those!

Racccon One: Brilliant! Why I think I hear him coming, OK guys, solder casual, play it cool...

Moid: Oh hi there Duck, hey you'll never guess what was wrong with that circuit? I just needed to reflow the solder, must've been a cold solder joint somewhere - it works now* Huh, Who would've thought a little thing like that caused all those problems? Couldda happened to anyone...


* ok at this point I have to snatch defeat from the jaws of victory. The circuit kind of works. It does not like a 15K resistor, nor does it like the 100K resistor which works perfectly on the breadboard version of the circuit; it in fact likes the 33K resistor that you suggested in the first place. So that is in place (socketed). The LEDs now flicker rapidly. The sound however has really bad ticking in it and the tremolo sound is a bit gentle (I've wrapped the LED LDR combos in black insulation tape so I know there aren't any light leaks). However most disastrously, the circuit only works when powered by a 9V battery! As soon as I plug it into a wall wart 9V DC plug the Blue LEDS stay on and do not flicker, and the Red LEDs turn off. Also if I connect the circuit to any other pedal that uses mains power (9V) the circuit does the same thing - blue LED on, Red off, no flickering. I realised that in the video that inspired this crazy circuit, the guy who made it only used a battery to power his pedal... and when I breadboard things, that breadboard runs off a battery as well (I never liked the idea of mains electricity going to something that I am sticking my fingers into)... so presumably there is something in the circuit design that breaks if it doesn't have a battery attached? That is pretty weird! I think this one might be being chalked up to nice idea, but isn't very practical / reliable... and it's weird that two different C106D transistors require totally different values of resistor to fire up... quelle strange!

I noticed when I play through the circuit that loud chords will distort (not a bad thing as such, but very surprising considering the audio part of the circuit is supposed to not be attached at to the tremolo part), and also as a note decays the trem can slow down a bit and then stop, and I have to mute the strings to force it back on! Also I wired the pot wrong so that you have to turn clockwise to slow the rate down, so I switched the wiring and now (even with a 100K resistor on the pot as well) it seems to lock up at both ends of the pot sweep, but play fine in the middle. Now I wondered if somehow the audio is getting into the current that makes the tremolo work and I think I might need to put a cut on row J between the 1n4148 and the blue jumper on the right side of the board - does that sound like a good idea? New layout below




I do hope you aren't pulling your hair out or cursing my existence at this point (thanks again for your patience!)

That would be my plea anyway! If this circuit doesn't work then I suspect my next brilliant circuit idea (which steals from this one) is possibly dead in the water...

[duck_arse]

there. now I've drawn a line.

two things; junior. how are his eyes for colour sight, good? get him to squint at the resistors. photos. we don't know what you've done, no matter how many layouts you post, if you don't show us the photos, so we can then look. if you post it, they will look, like costner sez.

is there any chance you have the pot wiper on its own, and the two ends of the pot joined? I have licence to ask because of the symptoms, and the lack of photos. [ comment removed here ]


also - small a, small d. thank you [from the possums].

[moid]

Hi duck, I see your line and I'll be careful not to trip over it (orders from the D.A. as Dylan put it!)

I have to report some changes... first, not only am I stupid; I am also innumerate... Your comment about checking the value of the resistors made me look over the circuit again and check everything (OK the resistors are correct - well I've changed one, but for a different reason) and I discovered that not one, but two capacitors were not what I thought they were... I put 2.2uF and 4.7uF on the vero, whereas I put 22uF and 47uF on the breadboard...

I think the above currently summarises my skills in circuit building.

So I spent this afternoon taking photos of the vero like you asked and after getting them ready and then noticing the screw up regarding cap values, so I now need to take new photos... We have family visiting tomorrow, but hopefully I will still have some time after they leave to get some better photos.

The photos of the pot are still valid - have  I wired the resistor across it correctly?





I have made an updated layout image (I will try to get some decent photos of the vero tomorrow to accompany this)



I did add the cut I mentioned in the previous post (row J) and this has changed things. The circuit no longer works with a battery, but does work if I use mains power to it... however it has a terribly loud hum sound that is louder than the guitar audio. If I connect the ground of the output jack to lug 1 or 3 of the Speed SPDT switch (whichever lug on that switch that is not in use) the hum goes away and the pedal works. So there is a ground issue here, although I don't understand why. There are unused ground pads on the 3PDT switch daughterboard, but connecting them to other ground points in the circuit makes the LEDs either turn off, or turn on, but not flicker.

If I switch speed modes I have to move the crocodile clip to the unused lug of the switch to make things function.

The Switch that alternates between forward and reverse sawtooth no longer works - I only have reverse sawtooth and both positions of the switch give me reverse sawtooth (which is annoying - the Red LEDs are pulsing in a different way to the blues ones that generate the reverse sawtooth and I would like to hear what they sound like). I have a bad feeling that having both LDRs connected to each other is a mistake... I think one of them cancels the other out. I realised that I didn't test this function on the breadboard version - I just moved the LDR from red to blue LEDs to hear the difference and assumed my wiring would enable this (I bet I'm wrong about that)

Oh and the circuit ticks loudly when I play through it - it is very quiet when I stop playing. The reverse sawtooth 'rise' speed stays at 140ms regardless of how fast or slow the pot is set - although it looks to me that the Red LEDs are changing at a different rate and might be making slower pulses (in terms of how long it takes the LED to light up)... but my circuit is ignoring them.

Moid Junior's colour vision is fine - he gets that from his mother. Sadly his actual eyesight is worse than mine; both my wife and I have poor eyesight and our son has sadly multiplied that... I blame poor genetics myself... I have checked all the resistors with a DMM (no power in the circuit while testing) and am confident of the correct values in the vero layout.

I know you probably can't give any advice until you see some photos; I just wanted to show some progress!

[moid]

Some photos:

The whole circuit


Close up of vero



Back of vero


back of 3PDT


Current Schematic

[duck_arse]

100k on the pot wiring looks about right. bad luck on the cap values, that's one of the things a casual observer can't help with, photos wise.

I think there is something not as you think, he said understatingly. the footswitch board can only work if it wires the switch as you have in the circuit diagram. you would need to confirm that, otherwise .... and there is some sort of grounding confusion going on. you should be able to get the oscillatings working without an ldr or guitar anywhere in sight, and you should be able to get undistored signal through the ldr [when they are steady lit properly] without any power on the oscillating parts.

and that cut you said you needed - if I was looking at your vero layout correctly, there should have been no need for any cut, cause there was no parts supposed to be connecting - not where I was looking anyway. so, we are back to having all the documentation be correct and sane, and then having the built match the proposed.

but the footswitch board. me, I'd lash a switch in to the wires, to see if it's wires wrong or daughterboard non compliant.



ahhh. your added post didn't display. now it does. I will need some time to look at it.

[moid]

Thanks for looking duck! The distortion is gone now, I forgot to say that before. The cut on Row J stopped the link on I11 and J11 from connecting the Pot wiper with the ground of the audio jacks - adding this cut made the circuit work with main electricity (but it no longer works with a battery - which is fine; I don't want to power it with a battery)

[duck_arse]

well, I have looked and compared, and I can't see it. the problem, I mean. obviously I can't say what about that switch in your circuit diagram, because it isn't there, so I can't say if it's right or not. but - all fingers are pointing to that particular black box, the footswitch board, that which we have no wiring diagram or schem or layout for.

only way I can figure to debug is to remove that board entirely. wire a switch as you think it ( can be a double pole toggle if you like ) to the oscillating section, and see if it functions right. then wire the audio part -- can even be on a seperate switch -- see if that holds up as you expect. and if it all comes together then, we/you have your/our answer/answer.

[duck_arse]

see how confused I am by that f/s board? it doesn't even connect to the oscillator section, does it. does it?