tiny tremoloOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

[pinkjimiphoton]

this is the layout i used...if it makes any difference!

[pinkjimiphoton]

went back to radio shack...they also have another 555 timer chip, gonna try it in the existing circuit and see if the problem goes away...
more later...

[pinkjimiphoton]

tried the other rat shack 555, doesn't work at all. tried lifting pins 4&5...no difference. tried shorting them to ground, as i seem to recall reading in this thread...no difference.
tried the original chip again, and the above tricks...doesn't work, tho shorting the pins to ground does make the led's other than the in/out one light up much brighter.
the circuit definitely works...but i suspect that lead dress has a lot to do with the issues i'm having, as i made them rather long to make it easier to wire up. wondering if the flying leads to the rate and status led's are contributing to the problem.
i checked inside tube amps by torres, just to read a little about vibrato ticking...said to try a .01 mfd cap across the large resistor in a fender circuit. i'll try it, but doubt it will matter.

one other weird thing i noticed, is it definitely matters which jack is used for input and output...one is out of phase, and the effect is much weaker!!

i suspect that trying to make a better mousetrap is what's got things messed up. i'm gonna try and "stupify" the circuit, and see if something closer to deadastronaut's original layout will work. i don't need a rate led all that much, tho it's cool to watch...and will try a true bypass to see if that matters, but i don't think it will.

worst case scenario, it's a hell of a techno bass drum.


anyways...gonna go play with it some, see what i can come up with...if anybody has any ideas, would be very appreciated.

curious...do you think maybe the size of the caps are doing this? it almost sounds like when a tube amp motorboats....wondering if maybe i got the size of the caps wrong? the two electrolytics are in microfarads, aren't they?

man...my brain hurts again...or would, if i had one.

[pinkjimiphoton]

lead dress definitely made a diff, but i accidentally shorted something or something, i dunno, now tho the light still flashes, it has no effect on the audio whatsoever. gonna try rob's original, see if that works. if it doesn't, i give up for now...

[pinkjimiphoton]

sorry for so many posts...i got it working, no ticks, clicks or tribal techno drums. i can't get the status led to work, i think there's a glitch in the layout, too tired to keep looking.
but what i found was...make the leads on the ldr and led as short as possible, and shrink wrap together facing each other. lead length didn't seem to matter at all, i've got it sitting out of a box and it's working...i un-twisted the wires. go figure. it still wasn't working , tho the noise was gone. i connected a ground jumper from the input jack ground, to the battery ground (i didn't put a walwart plug in it) and wango...there it was, a sweet warm natural sounding pulse. tried it with a couple amp models in my cybertwin, with clean and high gain models, and it did it's thing with no discernable noise.

hope this info may help solve this bugger...
peace, and thanks to rob and everyone, i learned a lot from building this toy. rock on!

[Perrow]

I've run into an issue. The circuit seems so straightforward that I went straight to veroboard. I assembled the pedal and it didn't work (classic response, right). I did notice one peculiar thing: the yellow rate LED came on for a split second right when the cord was put into the input jack and thus power applied. I noticed I could replicate the effect by taking the cord out, waiting a few seconds, and plugging the cord back in. Assuming I had messed up the layout, I went to breadboard and started over. Now, after assembling on breadboard, I get the same response. Immediately after I apply power the 5mm red LED (part of the vactrol) and the 3mm yellow rate LED flash for a second, and then stay unlit.

I'm using a Hitachi HA17555 timer that Futurlec had listed as a CMOS 555 (here's the datasheet: http://www.google.com/url?sa=t&source=web&cd=3&ved=0CDAQFjAC&url=http%3A%2F%2Fwww.classiccmp.org%2Frtellason%2Fchipdata%2Fha17555.pdf&rct=j&q=Hitachi%20HA17555&ei=Yl-CTfHKGs6htwf2tuneBA&usg=AFQjCNHYgNEUr-Xj15Q0fFpv1sW-rrvasg&cad=rja). It seems to have the proper pinout and all. Any help at all would be greatly appreciated. Thanks!

I got the same thing. You're using the limit resistor on the 9V+, aren't you?

Install a trimmer (or a regular pot) there and find out just what value this resistor should be, I had to go down to 820R before mine started blinking.

Edit: Careful though, I blew two leds using too low resistance (zero resistance actually, but be careful).

[deadastronaut]

@jimi, phewwwwww....that was a journey eh?...success!...

see, it can be done!..without a tick...

this is why i strongly recommend 'breadboards'..... i bb everything!.



@neutron:  i tried various 555's and all ticked apart from the ts555cn...when it had a 2.2k on the power...

this may obviously vary due to tolerances or ic you are using etc...try what perrow suggested, to find 'that spot with a pot ' ok.

[neutronarmy]

Thanks for the responses folks. I'll give that a shot today - good to hear the problem isn't some detrimental lack of understanding. I'll let you know the results! I'm excited.

[Perrow]

Thanks for the responses folks. I'll give that a shot today - good to hear the problem isn't some detrimental lack of understanding. I'll let you know the results! I'm excited.

I can totally relate to that, I've been in this thread from page one, and just recently breadboarded it (didn't have a breadboard before) and that non blinking led was totally frustrating. The problem was made even worse by the fact that without the resistor on the power, the leds died almost instantly.

[pinkjimiphoton]

@jimi, phewwwwww....that was a journey eh?...success!...

see, it can be done!..without a tick...

this is why i strongly recommend 'breadboards'..... i bb everything!.



@neutron:  i tried various 555's and all ticked apart from the ts555cn...when it had a 2.2k on the power...

this may obviously vary due to tolerances or ic you are using etc...try what perrow suggested, to find 'that spot with a pot ' ok.

rob and everyone, thanks so much!

yah, it works perfect. i DID find two possible mistakes on the layout... i didn't use a dc jack, so i use a 9 volt battery clip wired to the b+ connection on the board, with a switch to break the battery ground at the circuit board ground. so that was a very slight modification...

the three things i had to do to make it work were...

add a ground strap from the input jack ground to circuit ground on the board...suddenly it stopped ticking and motorboating, and worked great!

next, the bypass led...on the layout, it looks like the anode is on the top, cathode on the bottom. this is backwards! also, there's enough current to just pop an led..i blew out about 5 of them before i figured it out. i used flying leads to a little piece of perfboard, and added a 4.7 k resistor  to limit the current...used a 1/4 watt one, and soldered it to the little piece of veroboard, then soldered the other end to (i think) the cathode side of the led...worked like a charm.

tried it with my twin, and again, my marshall...no ticking, no noise, just a really transparent, warm tremolo effect that kinda reminded me of a univibe a little bit in some circumstances.

if anyone else can't get it to work, but can see the led flashing inside the shrink wrap, try connecting audio and circuit ground, i bet it will work.

tried the other radio shack 555, no dice, no nothing...the led just lights and stays lit. if you're in the states, and go to radio shack, you need the one labeled tlc555 low power timer ic, linCMOS timer 8 pin DIP. part number 276-1718. and you should be good to go!!!!!!!!!!!!

i have to cut out to new york for the day, will try and post pics and some kind of demo when i get back...

if you're having probs with the circuit, try my suggestions, i hope they work for you...


the only other thing i noticed is when i turn my guitar down, it turns down QUICK with this circuit...so i imagine a tiny buffer at the input will do wonders...

but i don't know how to do that yet!


great circuit, fun toy, and a satisfying experience, rob....thanks again mate, especially for the patience while i sorted thru this!!

good luck, everyone...

peace,
jimi

[neutronarmy]

Success! Thanks Perrow, Pinkjimiphoton, and deadastronaut for the help. 1.1k seems to be just about the right value for that Hitachi 555 if anyone else is using it. Thanks again deadstronaut for the excellent project.

[deadastronaut]

yay!...........

great stuff guys!....

[pinkjimiphoton]

i just got back from new york, was showing it off to my bro kevin...he's blow away...lol.

glad i could help a little bit...try and do a demo and upload some pics tomorrow...it was pretty before i started trying to debug it, now not so much...alot of the leads to the board are tacked together in a very disorderly looking mess...but i don't care, sounds great!

anyways..again, thanks, and best of luck to everyone who builds this cool little gizmo!
peace,
jimi

[Ankhe]

Hi,
may I use a 27k-94k ldr? I can't find any lower value one, and I don't really want to order one via the Internet.
I was thinking, maybe putting it parallel with other resistor would do the trick?

[Perrow]

Try any and all ldrs you can get your hands on

[ppaappoo]

hi after check out the first half of the thread, i'm lost. What is the final verified version of the tremolo pcb?

thanks

[deadastronaut]

this is the version i ended up with....works fine, bit of a volume drop when on though ok...(top of this page)

breadboard it first...perrow did a pcb version in this thread somewhere...have a look...

http://www.diystompboxes.com/smfforum/index.php?topic=87322.msg769565#msg769565

[pinkjimiphoton]

when i was trying to debug it, i ended up trying 3 or 4 photoresistors...the resistance range was from a bout 5 k in light up to about 15k, and it really didn't seem to matter much. hope that helps a little bit. i would imagine if you add a resistor in series or parallel to it, it shouldn't really matter too much!

the other thing i noticed is, if the ldr and led are touching, like in my original attempt, it clicks more...i put a slight space (oh, maybe a 16th of an inch) between them when i shrinkwrapped, and it stopped the ticking...i mean, even into a cranked up marshall with the gain pegged, i get no clicking or ticking at all now.

there IS a really slight volume drop when it's in, but i don't think it's too noticeable...
what i was wondering was, if we added a pull down resistor, something big like maybe a 1 meg from the input to ground if that would help with the signal loss?

all in all, tho, a really groovy pedal.

rob, could you suggest a buffering circuit to try and add to it? because it's shorting the signal to ground, is it better to buffer the in and out?

thanks!

[deadastronaut]

i agree it could do with a boost in there....

i think, and i may be wrong...which isnt unusual,

but a buffer between the in/out on the pcb to the switch might work.(looking at the vero)..not sure if that would also boost the bypassed signal too though!..just thinking aloud..

any decent clean boost should be ok, ....take a look in the gallery for 'clean boost'....probably a small vero in there...

of course its another pot as well....cheers rob.

[pinkjimiphoton]

lol...thanks rob...i am WAYYYYYYYYYYYYYYYYYYYYYYY TOO STUPID myself to figure it out, so i'll lurk till someone else does!!


i'm wondering tho if it would need in AND out buffers? and would that change the tone?

if it changes it, heck, i'd rather live with the slight volume drop...this is about the sweetest sounding trem i've ever played thru!
:thu: