UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

G6Tanuki · 21st Jun 2018, 11:38 am

Rather than using a COTS chip, why not do it the old way with a few discrete transistors? You'll probably learn a lot more about the workings of a SMPS if you can hook a 'scope to various points in the circuit and see what waveforms are there/how they change with differing loads.

I've built a few SMPS this way over the years: deceased Pye Cambridge radiotelephones will provide a nice potted transformer and a few NKT404 transistors. Sprinkle in some additional diodes and an OC81 or AF117 or three as a multivibrator.

21st Jun 2018, 11:38 am	#5
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,005	Re: Switched Mode Power Supplies Rather than using a COTS chip, why not do it the old way with a few discrete transistors? You'll probably learn a lot more about the workings of a SMPS if you can hook a 'scope to various points in the circuit and see what waveforms are there/how they change with differing loads. I've built a few SMPS this way over the years: deceased Pye Cambridge radiotelephones will provide a nice potted transformer and a few NKT404 transistors. Sprinkle in some additional diodes and an OC81 or AF117 or three as a multivibrator.