I'm working on an old hand held electromagnet (about 5" dia.) and need help identifying what size capacitor to use as a snubbing capacitor in parallel with the bridge rectifier.
The original magnet control used a selenium rectifier but from what I read, there should be a cap to smooth out the DC. Note it is just on-off and 120volt.
I have nothing to go from, there are no tags.
Help would be appreciated.
The original magnet control used a selenium rectifier but from what I read, there should be a cap to smooth out the DC. Note it is just on-off and 120volt.
I have nothing to go from, there are no tags.
Help would be appreciated.
A snubber device usually consists of a Polypropylene film capacitor with something like 100R in series with it.
If you work out the peak voltage and energy being switched an educated guess can be formed.
The capacitance varies between 22nF and 680nF depending on load and frequency.
Polypropylene Film Capacitors | RS Components
If you mean a smoothing capacitor then make sure the DC voltage of the chosen capacitor is not exceeded and the value of the capacitor could be between 10uF and 220uF depending on the demand from the circuitry.
If you work out the peak voltage and energy being switched an educated guess can be formed.
The capacitance varies between 22nF and 680nF depending on load and frequency.
Polypropylene Film Capacitors | RS Components
If you mean a smoothing capacitor then make sure the DC voltage of the chosen capacitor is not exceeded and the value of the capacitor could be between 10uF and 220uF depending on the demand from the circuitry.
Check out the http://www.diyaudio.com/forums/power-supplies/243100-simple-no-math-transformer-snubber-using-quasimodo-test-jig.html. Lots of good info there and a simple test board 
. I think there's even a group buy on for the pcb.
. I think there's even a group buy on for the pcb.- Status
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