555 supply voltage

Wendy

Joined Mar 24, 2008
22,170
OK, do you have a schematic to show us? That is generally a really good idea before buy parts. If you display such schematic the crew can give it a once over.
 

Wendy

Joined Mar 24, 2008
22,170
The schematic I drew there was to show one way you could run a 555 off of greater voltage. It was a schematic I pulled from my library by way of example.

Not without interfacing. There are ways to do it, such as the one I'm about to show for a relatively high frequency oscillator by way of example. The 555 controls a transistor, which in turn interfaces to the high voltage side.



BTW, a standard 555 can only handle 4.5VDC to 15VDC, while a CMOS 555 (totally different part) can usually handle 3.0VDC to 18VDC. The 19VDC is an internet myth, datasheets are your friend.
I talking a schematic of what your are going to do, which was a switching circuit using higher than rated voltage?

Show us what you are planning with an updated schematic.

I've lost track or your requirements. If you were turning on/off a solenoid (for example) half the circuitry is not needed.
 

Wendy

Joined Mar 24, 2008
22,170
OK, lets pin down some specs.

You have a high current 24VDC to 30VDC power supply.

You want to turn on and off a pump. What are the current requirements? Will the motor need to run in reverse?

If it is a simple on off function a single transistor will suffice, and I might change the zener for a equally simple 3 terminal voltage regulator (parts are very common and cheap).

What specifically is the criteria for turning the pump on or off? A sensor? Cycling on and off? Be as specific as you can.
 
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