Hi

I'm trying to create a driver for an H-bridge using a 555 Timer IC to switch the IGBT's on and off. I'm trying to get something like below. The difficult part is this has to have a pwm signal that will be controlled via a reference voltage. I have gotten that part to work using the 555 as an astable multivibrator, but not sure how to make it drive 2 IGBT's in every odd pulse and the other 2 in every even pulse. Any help would be appreciated.

 

Is using a 555 an important part of your objective? There are controllers designed specifically for this task that would be far simpler and better if what you really want to learn about is the H bridge part.

 

The 555 is the simplest solution I've found as well as cheapest, I'm sure they're others out there, just haven't found them. I'm very open to suggestions though. Except micro controllers. Would really like to do things without them, helps me to learn more.

 

Have a look at the datasheet for the SG3525A. I recommend the sheet from ON Semi.

The 3525 is a pretty ancient design. It costs more than the 555 but is still inexpensive and has many useful features built in. There are many more parts that are similar and many with better features and performance for some applications. The UC3825A is feature-rich.

If you really want to use a 555, you can accomplish what you want with an Eccles-Jordan circuit (which is not some weird cross between a pastry and a basketball shoe - and no one calls it by that name, but you'll find what you want using it )

 

By the way I realised I made a mistake with the picture in my first message. What i need is more like something below, where the red and blue signals come from 2 sources and the duty cycle of both can be adjusted to give a pwm output. Sorry if i'm not making sense, I'm new to all this. Can that still be achieved with what you recommended?