Solid State Buck Boost Convert SMPS Design

[codex653]

and just as something to say to everyone who reads this for future reference, i don't mind as much right now about the 555 driving the mosfet...i just want to get the thing built...it's ok if i have a lower efficiency at the moment, or if the mosfet doesn't switch as fast..i'm not going for mass production perfection quality here (atleast just yet)...since it has the lower efficiency, it will give me a whole 'nother project to work on with this, which sounds like fun!

i have already ordered the parts a while ago, with the timer, mosfet, among other things and for the base circuit, and i want to stick to those parts...even if it means a lower efficiency at the moment. i can always get the stuff later for the drive circuitry.

 

[Blueteeth]

It is honourable to build something from scratch for academic purposes, this is indeed how I learned about SMPS's, only moving on to 'specific' devices later.

That said, given the slower switching speed you're using for your MOSFET's, I assume you're also significantly lowering the power of your prototype. Lower efficiency, means more energy dissipated as heat. At 70% efficiency (possibly lower without tweaks), 30% of your input will go out as heat, mostly in the switches. For 100W, that's 30W to kick out as heat!
With low current driving for the mosfets, they spend more time 'half on', acting as resistors, and getting very hot.

Of course, you can just draw small power and ramping it up until your heatsinks get too hot.

Another great reference for academic purposes is DIY inverters. These convert 12/24v to mains at roughly 50/60Hz. You can of course increase this frequency and rectify the output(s) and many use nothing but basic logic oscillators, albeit at lmited efficiency (and therefore, power).

 

[codex653]

thank you blueteeth! yah, i'm just gonna see how all this goes with what i've got so far...i've got some pretty decently sized heatsinks that dissipated 60 watts for a transistorized amp i made before with no fan, so i think i should be good on that. granted it got decently hot, but i'm not gonna be dissipating that much power at all!