Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: acheld on December 23, 2018, 10:16:35 pm
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I'm restoring a 70 year old Heathkit audio signal generator (AG-10). The power supply states "full wave" rectification, but uses only two diodes, and I am not sure if they are working.
How does the attached circuit achieve full wave rectification with only two diodes? Every other schematic I've looked at has four diodes . . . (there is no center tap on this beast).
Chris
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It's a full wave voltage doubler. The top diode passes the positive half cycle to the top cap. The bottom diode passes the negative half cycle to the bottom cap. That covers the full wave. The caps are stacked on top of each other so the total voltage is double that of a single cap.
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It is often called Voltage Doubler. It is full-wave input and output.
There's only two half-waves, it should be (is) possible to rectify both of them with two diodes.
Also look at the standard rectifier scheme used with tube rectifiers. Two diodes (in one jug) and a center-tapped winding.
Do you have near 300V DC at the output?
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Thank you.
There was evidence of a prior "combustible event" as well as several errors in component selection (incorrect caps). I did not trust it to be safe, so I tore it apart and reassembling. As measured, ESR on most of the caps suggests they are goners. That is not a surprise, I guess, as it was first assembled in 1960.
I'm using it as an exercise in learning . . .
When it is wired up, I'll be testing and documenting.