i've been playing around with some 555's and a gargletron...

[foxfire]

so between Darron's optical tremolo and R.O.G.'s phozer i decided to try something in front of the gargletron i just made. i ended finding a schematic of what i'm gathering is a very common circuit for the 555. that's right, the Astable Multivibrator. the link for it is below. i breadboarded it today and, considering the low part count i think it's pretty cool. i know that C2 sets the speed range and, that R3 and R4 control the brightness of the leds. i was just wondering if there were any other mods i could do to it? i sent a lot of time reading about this chip but, most of what i read went right over my head. thanks i advance for any suggestions.
http://images.google.com/imgres?imgurl=http://www.electronics-project-design.com/images/LEDFlasherSchematic.GIF&imgrefurl=http://www.electronics-project-design.com/LED-Flasher-Circuit.html&h=329&w=344&sz=5&hl=en&start=33&sig2=h1Q1YBZlQUsqLOoXkUGM-Q&um=1&tbnid=GRmvSa_u1zzPgM:&tbnh=115&tbnw=120&ei=Yxt3R9DrKpSUeKeslFY&prev=/images%3Fq%3Dflashing%2Bled%2Bcircuit%26start%3D18%26ndsp%3D18%26svnum%3D10%26um%3D1%26hl%3Den%26safe%3Doff%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DN

[foxfire]

ever heard the saying, "A bird in the hand is worth more than two in the bush?" well it ain't true. i decided to wire up two 555's as astable multivibrators. i have a led and a led/ldr combo on each 555. so one leg of each lrd connects to the 470r going to ground (what was lug 2 of the gargle pot) of the gargletron. the other legs of the ldr's each get one the leads that would've been the outer lugs of the gargle pot or in other words they each get a filter. well i didn't like how that looked so i just used a 556. with a bit of tinkering it sounds really cool. having the ability to run each filter at different rates gives you a neat lushy watery effect.
now i'm guessing i'm not the first person to try this and, i'm guessing that there are better ways to do this? but hey, i got 2 days of fun out of it and i think i learned a little bit about stuff... in the end i plan on wiring this pedal up with a pot and the lfo on a switch so i can use it as a wah or fake phaser. 

[JasonG]

I would like to hear that one. Do you have any clips ?

[darron]

yeah. i'm really interested in some LFO's right now (: i wouldn't mind some sort of clip.

one thing that i would want to try is setting the rate with an optical source on the box, so when you click the switch with your foot it's really slow, and as you move your foot away it becomes faster. they use that effect often in pop vocals (not by foot i assume) and i think it would be great transfered to a distorted guitar.

i've got some 555s lying around. if there's a cool clip then i'd be further encouraged to get this crap of my breadboard to make something new. i bought some to make a atari punk console but never got around to it.

[foxfire]

'll see if i can figure out how to get some clips going then.

[Paul Perry (Frostwave)]

To get a speeding-up LFO, you could look at 555 oscillators that have voltage controlled frequency.
And, using a dual footswitch, you could use one switch to start a cap charging (via a high value resistor) so that the LFO builds up to a maximum rate.
Might be easier to use a CD4046, but there are voltage controlled 555 LFOs.

[darron]

at very worst i'd be happy with the effect plugged into the computer's audio input.

[foxfire]

i've never looked in to posting sound clips. whats the easiest way/or place to do it? i've seen a bunch of posts about this but never read them.

[darron]

don't use a wave file, too massive. make a mono mp3 of about 128kbps. what people normally do is then post them on some web space somewhere and just link to the file. your isp will often provide a small amount of web space. most of these guys have their own website though and use that. other than that there are sites that you can use that make it simple, but i don't know any off hand. i'll keep an eye out for next time someone posts a clip that's not on webspace. like photobucket, but for audio.

other than that, email us

i'd be happy to host it temporarily also.

[foxfire]

if you haven't gotten it yet i sent you a mpeg4 sample, hope it works. anyway i spent all day thinking about this instead of actually working. i think that using the 556 is a pretty simple way to get 2 independent LFO's but, you're limited to square wave. now if i used 2 LFO's like the ones you used on your optical tremolo then i could get both square and triangle. the only thing is that i really don't have much of an idea about the best way to go about doing this or if it's already an established pedal? i don't mind reinventing the wheel if i end up learning something along the way. i like what i have now so anything more will be a bonus.

[darron]

m4a file up  here

i like it (:

i'd be interested to see the schematic, even if i don't build it right away.

[ambulancevoice]

hmmm, sounds like a strage quiet mix of a tremolo, phaser and auto wah
too me anyway....
shut up!!!

...mmm chips

anyway, i remember finding a simple 555 lfo when i was interested in oscillators


sawtooth

[culturejam]

Sorry to bring up an old thread, but I was wondering if a schematic ever surfaced for the LFO that foxfire developed with the 555 and LDRs?

Thanks

[foxfire]

i had forgoten about this one. i'll try to whip up a schematic either tonight or the next. if i remember correctly it ticked with both circuits on the same power supply.
rylan

[culturejam]

Awesome. Thanks, man. 

[foxfire]

It's gonna be a bit before i'll have time to draw up a schematic but, here is a good site, http://www.kpsec.freeuk.com/555timer.htm#astable. i used a 556 which is just 2 555's. i remember having to adjust the brightness of the leds. making them too bright causes a tick. i think you'll find that this thing will tick no matter what if it shares power with a circuit that passes signal. i do also remember having a lot of fun playing with it though.
rylan

[Marc.yo]

you could  also use an integrator...which is merely a inverting op amp with a cap in the - feedback loop at the end of the 555 to get a sine output....not a great sine but it gets the job done. make sure you tinker with the cap value to get a good conversion...otherwise it'll look like a wanky sqine wave