UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - FM to AM converter

paulsherwin · 30th Sep 2018, 1:20 pm

It's not critical, and the oscillator will probably be fine without it, but it's a good belt and braces approach to decouple the power rails with a 10nF-100nF capacitor as well as an electrolytic. This is because electrolytics tend not to work very well at RF frequencies.

You can overthink these things. This is a very simple circuit and all it needs to do is oscillate. It's difficult to imagine anything that would stop this happening unless there was an actual wiring error or faulty component.

30th Sep 2018, 1:20 pm	#29
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: FM to AM converter - variation on a theme! It's not critical, and the oscillator will probably be fine without it, but it's a good belt and braces approach to decouple the power rails with a 10nF-100nF capacitor as well as an electrolytic. This is because electrolytics tend not to work very well at RF frequencies. You can overthink these things. This is a very simple circuit and all it needs to do is oscillate. It's difficult to imagine anything that would stop this happening unless there was an actual wiring error or faulty component.