PWM change frequency?

[supak111]

Is it possible to easily change the frequency of this PWM I got from ebay? I'm trying to use it to drive a car ignition coil and make arcs, but its not working. I'm guessing its because its frequency of 13khz is way too fast. If would be great if I could make it an adjustable freq PWM.


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310649883697

 

[Rleo6965]

I think this is a pwm controller only. You still need AC to DC pwm inverter ( power supply ) to be able to use it.

 

[supak111]

why do I need a ac to dc pwm to use this? I hooked this up to a small 12v DC motor an this PWM works fine to control the dc motor speed. Just doesn't work as a coil driver that's all.

 

[Rleo6965]

For clarification. Can you post sketch of wiring connection of this PWM controller and your ignition coil driver that does not work.

 

[supak111]

Maybe I'm connecting it wrong but there are 4 connections on the PWM, 2 are power in to the PWM and two say out for motor. I just connected the power to the 2 pwm, and connected the coil to the two that are suppose to go to motor

PS I don't have a coil driver, I though the PWMs pulse DC would drive the coil and make it spark continuously

 

[Rleo6965]

You still need to use ignition coil driver. Even you correctly the pwm able to function. Coil induction voltage will reached 250V AC and surely will damage your pwm.


I able to designed and successfully installed a MultipleSpark CDIS to my car. It had 625 uS between pulse or 1.6 khz pulse. Note that capacitor was used for charging current. Your 13khz pwm was too fast especially use for inductive charging for ignition coil.