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Circuitbenders Forum => Circuitbending discussion => BENDING TIPS => Topic started by: wax+wire on February 10, 2015, 07:14:47 AM

Title: 555 oscillator + transistor to turn bends on and off
Post by: wax+wire on February 10, 2015, 07:14:47 AM

I stumbled upon this excellent idea : http://www.nerdybynature.com/2009/10/06/glitch-lfo/#comments (http://www.nerdybynature.com/2009/10/06/glitch-lfo/#comments)

It takes a basic 555 lfo circuit and hooks up a transistor to open and close the bend (or anything from what I gather)

Only issue, hooking it up doesn't seem to work for me.

What possible transistors would work in here?

Or should i stick a load resistor before the switch?  (i am running it off 7.5v - 9v from a casio sk

Title: Re: 555 oscillator + transistor to turn bends on and off
Post by: wax+wire on February 11, 2015, 12:09:29 PM

a 2N2222a transistor worked sweet.

i put a 1k resistor in line with the base of the transistor, but i don't think it does anything. 

Title: Re: 555 oscillator + transistor to turn bends on and off
Post by: Circuitbenders on February 11, 2015, 03:24:41 PM

A 1k resistor in line with the base will limit the current used to turn on the transistor. This is necessary if you're using something like a microcontroller output to drive the transistor, as theres a limit to how much current the IC can supply. Probably an idea to read up a bit on how transistors work. Theres load of stuff on the net.

You might get better results using the 555 to drive a 4066 switch, or even a reed relay being switched by the transistor. How well a basic transistor switch works will depend a lot on what its switching.

Title: Re: 555 oscillator + transistor to turn bends on and off
Post by: wax+wire on February 12, 2015, 08:29:12 PM

Thanks.

I think i do need to read up on them.  when i hit a problem i started reading about it, but it did my head in a bit to be honest.  might need to start at the dummies version.