UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Noise issue with DIY variable PSU and audio amplifier

G6ONEDave · 9th Dec 2022, 3:33 pm

I hope that the circuit works as expected for you. Do check how much head room you need for the 7809 to work correctly. If I remember correctly the low drop out varieties don't need as much head room as the bog standard types.

I've not checked the data sheet for the UPC1212C to see how much current it draws, possibly 250mA or less but once you know the normal operational current you can work out the dropper resistor value using ohms law.

Dave

9th Dec 2022, 3:33 pm	#43
G6ONEDave Octode Join Date: Dec 2019 Location: Owston Ferry, North Lincolnshire, UK. Posts: 1,701	Re: Noise issue with DIY variable PSU and audio amplifier I hope that the circuit works as expected for you. Do check how much head room you need for the 7809 to work correctly. If I remember correctly the low drop out varieties don't need as much head room as the bog standard types. I've not checked the data sheet for the UPC1212C to see how much current it draws, possibly 250mA or less but once you know the normal operational current you can work out the dropper resistor value using ohms law. Dave __________________ Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battlestar Galactica)