[Amps] Series Capacitor Strings in HV Supplies
2 at vc.net
Thu Feb 27 01:04:28 EST 2003
>I have formulated a new theory which offers very convincing proof that the
>traditional 'equalizing' resistors used with series-connected electrolytic
>capacitor strings are NOT necessary. I realize that this contradicts the
>prevailing wisdom, not to mention the design of hundreds of commercial amps
>that have come and gone.
In days of yore, electrolytic capacitors were less than uniform, so V
equalizers made sense. Currently mfg electrolytics are quite uniform, so
V-equalizers are probably of little or no value, except for discharging
them after use.
>In lieu of just passing off what might be construed as idle speculation, I
>have also done some meaningful practical work which supports my conclusion.
>Specifically, I have been running 3 power supplies here over the last two
>years with no resistors, one of them in my 'main' amplifier which is on the
>air almost every day. To date, no sign of trouble. In addition, I have made
>periodic spot checks of the voltage division between C's in each of the
>supplies. Again, no unusual imbalances.
>Now, I am preparing to make a public disclosure of my theory, which should
>of interest to anyone building medium to high power amps. Stay tuned for
>Meanwhile, I would like to hear any meaningful anecdotal data which supports
>the old belief: that without balance resistors, an imbalance in the leakage
>currents can lead to destruction of some C's. There are plenty of cases
>the resistors themself failed, which guarantees a destructive imbalance
>(that has happened to me).
Good point. High accuracy/high reliability MOF resistors are much
better than wirewound or carbon-comp resistors.
>But has anyone ever seen or heard of a case where
>'unequalized' capacitors blew? Unfortunately, few if any have ever dared to
>even try it. The old myth was born many years ago and everyone is afraid to
In the good old days, electrolytics were not uniform.
>Eric von Valtier K8LV
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
More information about the Amps