Re: rectifier waveform

John Jardine. wrote:
I have tried to get similar waveforms in my simualation. After I
increased the
stray inductance to 500uH, it looks very similar. The remaining
difference are
bursts with about 100kHz repetiton rate when the diodes switch off in
every cycle. Maybe your scope doesn't show that because of the
choosen sampling rate.
It would require a sampling rate of 1MHz or faster. The spikes
depend on the diodes too.

Best regards,
Helmut


I used a 'kit' transformer in the sim. With a K less than 0.995, the
500kc ringing makes the sim very tedious.
Real life, a 100MHz scope, 100ma and IN4005's showed no nasties,
pretty much like John F's pics but smoother.
A floating measurement using two probes on the 14V~ bridge input gave
17V~ and 9V~ in quadrature. Ties in nicely with a 240V supply and
measured 30pF interwinding capacitance.
john

I found that just a resistor across the secondary pretty much cures ringing,
at least better than capacitors across the diodes. Choose R to be as small
as possible with dissipation and transformer current in mind. With 14V~ 1k
should be sufficient for a 10VA tranny.
--
ciao Ban
Apricale, Italy


.

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