I have been looking at building a headlamp circuit for a hub dynamo that gives increasing output with speed.
A series-resonant circuit that peaks near the expected top speed looks a good way to do that, but capacitor
choice seems not straightforward. Electrolytics are compact and have adequate ripple current ratings, except
that all the data sheets I have looked at have a steep derating of maximum ripple with falling frequency.
The tables typically have a low value of 50 or 60Hz, so it is hard to know if such circuits will over-drive
the capacitors.
On the other hand, this article suggests such ratings are very conservative at expected temeratures:
https://www.newark.com/pdfs/techarticles/kemet/Ripple-Current-Capabilities-Technical-Update.pdf
Does anyone here have practical long-term experience?
Reports of loss of brightness, measured loss of capacity, or even popped components would be
interesting, but so would reports that everything is fine. And how aggressive is your circuit?
Capacitor bias method (if any) may also be relevant.
A series-resonant circuit that peaks near the expected top speed looks a good way to do that, but capacitor
choice seems not straightforward. Electrolytics are compact and have adequate ripple current ratings, except
that all the data sheets I have looked at have a steep derating of maximum ripple with falling frequency.
The tables typically have a low value of 50 or 60Hz, so it is hard to know if such circuits will over-drive
the capacitors.
On the other hand, this article suggests such ratings are very conservative at expected temeratures:
https://www.newark.com/pdfs/techarticles/kemet/Ripple-Current-Capabilities-Technical-Update.pdf
Does anyone here have practical long-term experience?
Reports of loss of brightness, measured loss of capacity, or even popped components would be
interesting, but so would reports that everything is fine. And how aggressive is your circuit?
Capacitor bias method (if any) may also be relevant.