555 based Transformer Driver schematics needed

Driving an xfmr - to what end?

What's the purpose of the design. If you want to draw more than a few milliamps, you probably should consider using something like the LM3524 -- this chip can do a few hundred milli-amps, and the frequency is easily controlled by an RC network. It's kinda the low end of switch mode power supply design chips, motor control, but works. You can control the duty cycle of the chip by drawing from an internal reference voltage pin and feeding it into an internal amp. They cost less than $0.50 if you shop around.
LMAO. No offence to you Electro. But the people in radio shack don't even know what half the stuff they sell is (at least at the stores near me).

Sorry I forgot about the power requirements. I was planning on using an external transistor or SSR. I plan on making one to drive a car ignition wire for a jacobs ladder and one (or more) in my car to power various accesories.

Thanks David


2002-04-12 4:41 am
Go to Radio Shack and find Engineer's Mini-Notebook 555 Timer IC Circuits by Forrest M. Mims III (orange book). Open the book from the back. There you will see a 555 timer circuit that can power a neon light from a nine volt battery. Also it can power a 60 watt incadensent bulb. However, 555 (single) or 556 (dual) can only output about 200 milliampes, so use a MOSFET and a high power transformer for higher wattage output.
If you are going to drive a car ignition coil to get HV, get one from a car that didn't use breaker points and drive it with a IRFP460 fet on a heatsink using a 4-5 mS on-time pulse at up to 300 Hz using a 12v supply. The coil current through the fet ramps to about 6 amps. Put a 100nF 400v cap across the fet from source to drain. It is a good idea though not absolutely necessary to put a transil diode ~400v across the cap / fet. The fet should avalanche and protect itself if the voltage goes much over 500v on the primary (50kV on secondary) but it's better to use an external clamping device such as a transil.