Anyone know a very basic circuit for flashing LED w\rate pot

Wild Zebra

I've seen lots of circuits, but non with a rate pot. (probaby a matter of replacing a resistor with a pot huh? I'm sure if I looked hard enough I would eventually find one. But I reckoned some one here would already know. Also it would be nice if it could be tapped right into a circuit powered by a 9V. Thanks y'all

elektro80 · Posted: Fri Sep 29, 2006 8:46 am Post subject:

I think such a circuit was in the old 555 examples manual thingie.

blue hell · Posted: Fri Sep 29, 2006 9:28 am Post subject:

http://www3.telus.net/chemelec/Projects/Flasher/Flasher.htm

oh and this one is nice : http://www.uoguelph.ca/~antoon/gadgets/555/555.html

and another fun thingy : http://www.falstad.com/circuit/ex-555.html

State Machine · Posted: Fri Sep 29, 2006 11:28 am Post subject:

If you plan to use a 9V battery, may I recommend the ultra LOW power CMOS version of the 555 timer. The BJT based 555's will suck the power right out of your battery. Very Happy

I like the ramping circuit.

Here is the data sheet link from Intersil:

http://www.intersil.com/data/fn/fn2867.pdf#search=%227555%22

Bill

nisios · Joined: Sep 02, 2006 Posts: 49 Location: Lisboa - Portugal

i have made this one... the schematic may have errors.
I can make another if you like.
http://electro-music.com/forum/topic-13194.html

Mikmo · Posted: Sat Sep 30, 2006 12:08 am Post subject:

Check this from my site :

there's both veroboard and real PCB layouts for a simple 555 based "lfo" LED flasher with potentiometer rate control - very simple circuit just a handfull of components. I used it for triggering sounds in a circuit bend toy, but it is very general.

http://www.mikmo.dk/cblfo.html

You can experiment with the capacitor / resistor values to get the range you want.

Wild Zebra · Posted: Sat Sep 30, 2006 7:34 am Post subject:

Thanks everyone for the suggestions I think I'm going to go for yours mikmo. Thats kinda what I'm looking for. If I already have a circuit with a 555 or 556 I reckon I can tap off of that chip?

Mikmo · Posted: Sun Oct 01, 2006 2:08 am Post subject:

Yes i guess you should be able to connect a LED to an existing circuit, just remember the current limiting resistor, or the LED will have a very short life.

Only potential problem i can see is if the existing circuit is running at a frequency in the audio range, in that case the LED will not flash, but just be permanently lit.