Bistable 555

Thread Starter

Wendy

Joined Mar 24, 2008
21,914
Helping someone with another thread I think I've figured how to turn a single 555 into a flip flop. Check it out...



This will end up in my 555 projects collection if it works. Confidence is high that it will.
 

Thread Starter

Wendy

Joined Mar 24, 2008
21,914
The original was for an LED flashlight, and used 2 555's in a traditional manner to make the flip flop.

The thread at this site wants to make a foot switch for a fog lamp.

The only real claim to fame this design has is it has eliminated the extra inverter, and still has a nicely low parts count.
 

hgmjr

Joined Jan 28, 2005
9,029
Bill,

What you are aiming at is to provide a circuit that permits a momentary-switch to act like an alternate-action switch.

The circuit you have posted would appear to do just that.

The related post is this one. I think.

hgmjr
 

Thread Starter

Wendy

Joined Mar 24, 2008
21,914
That's the one.

AudioGuru has a schematic he posts using transistors. It think this beats it in simplicity.

It is also a decent demonstration in how to make a flip flop flop.
 

Audioguru

Joined Dec 20, 2007
11,251
My circuit uses Cmos inverters so its supply current is almost nothing. It can drive a transistor or a Mosfet to turn things on and off using hardly any current when off.

A 555 draws 3mA to 15mA all the time. A Cmos 555 draws 50uA to 400uA all the time.
 

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retched

Joined Dec 5, 2009
5,208
(Twenty years ago, yesterday)

Bill, you are on a mission from god. This mission is to find all practical and impractical uses for the readily available IC known to the world as the 555. Get started.
 
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