I need this to drive a mosfet, 10A load. Do I need two NE555, or can I do it with one device?

 

I need this to drive a mosfet, 10A load. Do I need two NE555, or can I do it with one device?

Does it have to be a 555? Control in the 1-5% duty cycle range might be better with an op-amp square wave generator. That trick is commonly used for full-range PWM control.

 

You may have observed that such short duty cycles can be a challenge with the 555.

1) Have you tried using steering diodes to control the charge/discharge cycles?
2) A conventional Schmitt inverter can give short duty cycles too:

Source: http://www.cappels.org/dproj/aciprobe/ACCurrentProbe.html (@DickCappels )

 

Does it have to be a 555? Control in the 1-5% duty cycle range might be better with an op-amp square wave generator. That trick is commonly used for full-range PWM control.

Well, I have a bunch of those 555's, but I also have a few other cmos/Lm/Op etc. devices. What I am doing is making a powerful current driven electric fence charger for my garden, a "weed-burner" if you will, and I only want to drive it "on" for a short period, for safety, my safety. My previous attempt worked great, but a herd of elk moved in this past winter, and stayed. They go right thru my h-v fence (useless when rain torments my insulators) so I need something more authoritative, but I don't want to run 30mA on full-time, as that is unsafe.

 

I made a low duty cycle 555 circuit last year, it flashes a high power LED just briefly every 3 seconds or so. I made it to put next to my laser level so people would see it and not trip over it. I can look the diagram out if you think it will be of use to you.

 

I need this to drive a mosfet, 10A load. Do I need two NE555, or can I do it with one device?

Yes it can be done with one 555, you need to use steering diodes using the hysteretic circuit , using pin 3 to charge and discharge the capacitor .