In Reply to: RE: Is this feasible? Rectifying 6.3v for heaters posted by Audio Pete on December 21, 2017 at 07:16:51:
Hi Pete,The capacitors provide the reactance to "ballast" the current through the LED (in this case ~ 6mA). The voltage drop across the LED is ~ 2 volts at that current. Yes 1 cap could have been used but for the same current it would be 1.5 microfarad. I chose to use two as the voltage one side of the transformer is going positive as the other side is going negative. This is an effort to keep AC on the leads to the LED at a minimum.
I have attached a picture of the schematic of the subwoofer amp which forced this regulation of the Citation 4 supplies as protection against the fridge. Sorry the schemo is beyond rough. It was the schemo I drew as I was designing the amp and got scribbled on during the refining of the circuit. I really need to draw a clean copy which is more easily understandable. I hadn't looked at it for about a decade and I had to struggle and I designed it.
The output transformer is a repurposed TV power transformer. I believe it came from a late 40s Zenith TV. I did not scrap the TV but found the transformer surplus. The push-pull primary is what formerly fed the 5U4 rectifiers. The source winding is made of a center-tapped 12.6 volt winding to which a 5 volt winding is added on each side. That output circuit is inspired (stolen) from Mac tube amps. The speaker winding is what was the 120 volt primary.
I don't know how to attach more than one picture so I'll put the protection circuit in another post.
Phil
Edits: 12/21/17
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- RE: Is this feasible? Rectifying 6.3v for heaters - coffee-phil 14:28:51 12/21/17 (1)
- RE: Is this feasible? Rectifying 6.3v for heaters - coffee-phil 14:48:33 12/21/17 (0)