Building a VV mod on a budget

I've been interested in PWM (pulse Width Modulation) and how to integrate it into a variable voltage power supply. I suspect, with a minimum of components, it is possible to do a homemade VV mod. This is a design for a motor controller, but it looks like it would drive an atty just fine

The basic circuit uses an inexpensive 555 timer IC and a mosfet (plus a few other supporting components) .. I think it would all fit on one of Madvapes mini PCB's .. which would allow one to build a 3-AA modbox VV ..

The problem I am working on is the frequency of operation. As designed, it will oscillate at 144hz, C1 and R1 determine the RC time constant. By juggling these two component values, it should be possible to crank up the oscillation to 14,400, possibly 28,800 hz or higher.

Jes thinking .. check the tutorial for more info ... DPRG: A Simple PWM Circuit Based on the 555 Timer

 

There are threads all over the forums about this. You can even get the Vregs for free. Do a search for Evercool on ECF.

 

I have read posts about the TI regulators, have 3 diff ones in the shop for future use, thought this simple circuit would allow you to put a VV together for just a couple of bucks. Like I said, I just found it interesting and wanted to share it with some of the more technically-minded members.