555 based Transformer Driver schematics needed

PhaseShift · 30th June 2002, 04:24 AM

I need a schematic to drive a transformer from a dc power source that is based on a National Semiconductor 555 chip. I would like to be able to adjust the frequency. I would really like to learn how to use chip myself so the simpler it is the better.

Thanks David

Electro · 30th June 2002, 04:33 AM

How about stopping by Radio Shack?

jackinnj · 30th June 2002, 04:42 AM

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.

PhaseShift · 30th June 2002, 05:00 AM

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

Electro · 11th July 2002, 06:18 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.

Circlotron · 11th July 2002, 03:43 PM

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.

GP.

SteveG · 11th July 2002, 05:51 PM

this may sound obvious, but did you go to national.com and download the datasheet? They have a lot of example circuits in there, and also tell you how the chip works (it's very simple).
Steve

30th June 2002, 04:24 AM	#1
PhaseShift diyAudio Member Join Date: Jun 2002 Location: Illinois	555 based Transformer Driver schematics needed I need a schematic to drive a transformer from a dc power source that is based on a National Semiconductor 555 chip. I would like to be able to adjust the frequency. I would really like to learn how to use chip myself so the simpler it is the better. Thanks David

30th June 2002, 04:42 AM	#3
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	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.

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30th June 2002, 04:33 AM	#2
Electro diyAudio Member Join Date: Apr 2002	How about stopping by Radio Shack?

30th June 2002, 05:00 AM	#4
PhaseShift diyAudio Member Join Date: Jun 2002 Location: Illinois	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

11th July 2002, 06:18 AM	#5
Electro diyAudio Member Join Date: Apr 2002	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.

11th July 2002, 03:43 PM	#6
Circlotron diyAudio Member Join Date: Jun 2002 Location: Melbourne, Australia	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. GP.

11th July 2002, 05:51 PM	#7
SteveG Account Disabled Join Date: Jan 2002 Location: Newton Falls, Ohio	this may sound obvious, but did you go to national.com and download the datasheet? They have a lot of example circuits in there, and also tell you how the chip works (it's very simple). Steve

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