ForumsDIY ← Designing oscillating circuit for DIY DC -DC converter

Am building a power supply that uses a transformer which outputs 24v rms. The problem is it uses various sensitive components such as an LCD. I think I have thrown together a buck converter to solve this issue. However am stuck on how to drive the MOSFET since I can't use a 555 timer because I don't have a 5v rail.

I have a feeling am trying to run before I can walk but hey. Ofcourse I can just buy a ready built dc-dc converter but I thought I'll have a go at building a crude DIY one. Not too bothered about efficiency.

Here's what I've done but am not getting 5v. As previously mentioned the output voltage vin * duty cycle which is 5.1v. Am going to stick this into a 3.3v reg.

You don't want me designing any circuits! Maybe Brian will chime in if he has a minute.