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RE: Matching diodes in a 'diamond' diode rectifier?

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In Reply to: RE: Matching diodes in a 'diamond' diode rectifier? posted by andyr on October 13, 2024 at 20:47:07

Hi
Not sure what your meaning with the two secondaries part, can you draw that circuit? There should only be two connections to the bridge from a transformer. Often a there is center tap or series connected secondaries with the center point being grounded, then the bridge circuit produces equal + and - voltages with respect to ground (that center tap point)

The "on" voltage for a normal diode is around .6V but they should all be very similar. Matching isn't necessary and a way to look at it is the "on" direction it conducts with a low effective Resistance (but also a .6V threshold) but in the other direction it's an open circuit.

Follow Ups:

RE: Matching diodes in a 'diamond' diode rectifier? - andyr 15:30:29 10/14/24 (2)
Sure, Tom.

This is to produce a single, +ve DC rail - so either one of the transformer secondaries can be attached to the two 'AC' connectors ... or both can, in parallel.

Some info I have subsequently received suggests that, if I want to get anal then - due to the diodes' "forward voltage" - it would be best to have the sum of the Vfs of the 2 diodes on the 'top half' of the diamond bridge equal to the sum of the Vfs of the 2 diodes on the 'bottom half' of the diamond.
- RE: Matching diodes in a 'diamond' diode rectifier? - tomservo 16:42:16 10/14/24 (1)
  Yes, the configuration where a center tapped transformer or two secondaries in series to make a CT is what it sounded maybe like. That config has the ground at the center tap and the Bridge rectifiers output is now plus and minus Voltage with respect to ground.
  Note sure a tiny difference in on threshold makes any difference once one has more than a couple volts being rectified. Are you making a bridge out of separate diodes?
  
  There diodes that have a lower threshold V than generic silicon diodes if that matters, look for "shottkey" diodes
  - RE: Matching diodes in a 'diamond' diode rectifier? - andyr 19:15:31 10/14/24 (0)
    Thanks, Tom,
    
    Yes, I am making a bridge out of 4 separate diodes.
    
    End result is 24/25v DC.
    
    I will look up Shottky diodes.

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