Ansil?...Munky? Flashing 555...

[petemoore]

Has anyone seen the flashing 555 LED circuit Ansil posted a while back>?
 Just a small hanful of parts and the LED starts flashing at various controllable rate..nice..but I can't FInd the dern widget...
 1rst Time Successes are the best!!! I put together an inductorless Opamp Wah [GEO] and buffer using a DUAL OA, also two batteries for V+, V-, and Gnd. [for the first time, and it worked perfectly], I used the OA Operations page for the power supply with two 10uf's.
  This is what I want the timer for. I found a couple LDR's and in parallel, they go from about 30k to 1M~, I want to use them for the V/R for the wah. I'm counting on the LDR slowness to get a decent sweep rate or hope I like the resultant effect of a 'stuttery' sweep rate...I would like also for the first time to sucessfully implement the LDR's into a build...I don't know what 30k Resistance of the V/R will sound like in the circuit, but I'm having fun with it so and that's working...
  I used an .0027uf for the -OA input and an .0068uf for the other one, also tagged on a 1k to the 500k wah pot, to kill the oscillations at near full treble, still plenty of high end...
 All in all a pretty good day!
 Also, as if this wasn't enough...I burned my first CD!!! Hooray!!! I think it sounds PDGood...course it's my music on there...I didn't do alot of final mixing on all the tracks...but the thing's WORKING...alot of buttons drivers, get inside..do unplug/plugin startups, shipping of Driver CD, other hurdles...feeels Greeat when you 'finally get it, play it on the boombox and can say it's all worth the while!!! Good thing too...I got aN "Audio Disc is Full" message when trying to record this morning

[brett]

Congrats about the CD. Very cool    
I've sent private email about the circuit, but might get it up on my web site this arfternoon ( forum-time).
cheers

[brett]

Hi.  Sorry Pete, I forgot to mention in the email that a couple of changes are needed to the circuit to get 50% duty cycle.

Also, because others might be interested, here's the circuit


Do the following for approximately a 50% duty cycle;
1.  replace the 50k pot and associated 4.7 k resistor with a 1k resistor
2.  replace the 4.7k resistor between pins (2&6) and pin 7 with a 100k pot and 1k resistor.
cheers

[petemoore]

Thanks. I could try that one...
 I see NE555 'astable', not knowing what 'astable is.
 I have a timer from RS labeled '555 TIMER'.
 Do those need to be Red LED's?
 I remeber another circuit I built that Ansil posted, it didn't do 50% duty cycle which is what I think I'd want.
 Also, the right hand side of the Schem looks to be cut off, and there's a .001 [uf?] cap there ...ok...looks like it goes to ground there.

[brett]

Hi.

I see NE555 'astable', not knowing what 'astable is.
I have a timer from RS labeled '555 TIMER'.
Do those need to be Red LED's?
I remeber another circuit I built that Ansil posted, it didn't do 50% duty cycle which is what I think I'd want.
Also, the right hand side of the Schem looks to be cut off, and there's a .001 [uf?] cap there ...ok...looks like it goes to ground there.

"astable" is the mode for the 555.  ie non-stable or flip-flopping
The leds can be any type.  The 555 can put out a big current, so you could drive several if desired.
The right side of the schem is cut off, because this was just part of a larger circuit.

stay cool

[gez]

Hi.  Sorry Pete, I forgot to mention in the email that a couple of changes are needed to the circuit to get 50% duty cycle.

Also, because others might be interested, here's the circuit


Do the following for approximately a 50% duty cycle;
1.  replace the 50k pot and associated 4.7 k resistor with a 1k resistor
2.  replace the 4.7k resistor between pins (2&6) and pin 7 with a 100k pot and 1k resistor.
cheers

Brett, if you want a true 50:50 duty cycle, wire these up as you would a Schmidtt Trigger oscillator.  One less component too.

Connect pins 6 and 2 together and a cap from these pins to ground.  The resistance chain which sets the rate connects from the output (pin 3) to pin 6 & 2.

4&8 connect to V+, pin 1 to ground.

The other advantage of doing it this way is that you free up the discharge transistor, so you can use it to drive a LED without any loading effect on the output (though you only get a square wave of coarse - nice for choppy trem).  Connect up your LED & resistor from V+ to pin7.

Try it, it's a lot better circuit...

[gez]

Here you go...



f = 1/(1.4 X R X C), where R is the combined resistance of the stop-resistor and whatever's on the pot.

(lot simpler)

You can always tap the signal at pin 2/6, which is a non-linear triangle.  But you need to buffer it as the cap is easily loaded.

I would advise you to use a 7555 Pete.  The current consumption of normal 555s puts them beyond battery use and they often produce large current spikes, which makes them prone to ticking.  If you want more than 1 LED, stick another in series with the one shown and adjust resistor to suit.

[Peter Snowberg]

That is a wild way to hook up a 555!    :!: I love it.

Another way to get a 50/50 square wave is to feed the output to the clock of a D type flip flop with the inverted output connected to the D input. Since most flip flops are doubles, you can wire the second the same way and you end up with the second flip flop outputting the 555 frequency by 4. That can be useful for long periods or when you want to use smaller caps in the oscillator.

[thomas2]

inductorless Opamp Wah? where can i find it? didn't see in in GEO.. could someone give me a link or something? i have two unused volume pedals waiting for this kind of projects..

[Torchy]

inductorless Opamp Wah? where can i find it? didn't see in in GEO.. could someone give me a link or something? i have two unused volume pedals waiting for this kind of projects..

Tim Escobedo's site ... fantastic wee toys      

http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html

[gez]

That is a wild way to hook up a 555!    :!: I love it

I wish I could say it's my own idea, but it isn't (apart from the LED plumbed into pin 7 it's lifted from an old book).  Makes you wonder why everyone does it the other way though.

One thing I did come up with was to wire the discharge trannie to short the cap so that you get a sawtooth.  Simple way of doing it as it doesn't involve any discrete actives.

The above way of doing things makes PWM easy too (diodes and pot trick).

[Ansil]

http://geocities.com/austenfantanio/weedingout/


all my old stuff well 68% of its here.

http://geocities.com/austenfantanio/weedingout/mytrem.htm

this is what i used to light up the led to drive the ldr into submission. works nicely.

[petemoore]

Ahhh...there it is!! Thanks for posting it and all else Ansil!!!

[Ansil]

no problems sorry for the late reply there i dont' get online very much and when i do i have a ton of questions to answer about the miniamps. so much that i am starting a faq.  getting the new bits in today so hopefully we can get the the things off to the painters.

[brett]

You can always tap the signal at pin 2/6, which is a non-linear triangle.

Pete, if you're still watching, you might want to use this waveform to drive your LED.  A buffer will be needed.  An emitter-follower such as a 2N5088/9 would do.  pin2/6 to base, emitter via a 10k resistor to ground, collector to 9V.  Tap the LED and a 1k resistor from the emitter, and run them to ground.  I *think* that'll work.

have fun

[petemoore]

...I don't know what happenned...I thought it would wah with the LDR's at least a little bit...er maybe it did...seemed kinda bassy all the time too  I put the pot back on it, it's wahing again just fine, interesting sounding wah too.
 I post a new topic [?] on V/R's

[gez]

If it sounds bassy all the time there's too much resistance on the LDR.  This either means the LED isn't flashing (bad connection/LFO doesn't work) or the current running through it is too low.  Time for some testing!:)

Could also be the min resistance of the LDR is too high (less likely to be your problem, unless the circuit is badly designed)