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Topic: What size capacitor needed to power solenoid? (Read 4 times) previous topic - next topic

retrolefty

#5
Mar 26, 2011, 05:02 pm Last Edit: Mar 26, 2011, 05:54 pm by retrolefty Reason: 1
This concept of using a hugh capacitor to make up for an underated voltage source is bound to be problematic in practice. How often are you going to be turning the solenoid on and how long will the solenoid need to be on when you do activate it?

Lefty

pwillard


redtank

Thanks for all for answers, I'll check out the links provided. I will be cycling the solenoid every 5 seconds, but just for a brief instant, < 50ms.

Cris

Grumpy_Mike

I'm with lefty on this one, with these sorts of currents you are just asking for it.
That link was for a small current model railway.

Remember that the PSU will probably go into current shut down trying to charge up a capacitor of that size. Also the ripple current rating on the cap is going to be vastly exceeded.

MarkT

The ripple current rating is mainly about overheating, not instantaneous overload of the plates - I doubt if manufacturers quote ripple currents for low duty cycle conditions?  What's needed is electrolytics of the same sort of grade as used for flashguns, but with a lower voltage rating.  It may prove difficult to get enough current without going for high ripple-current ratings and using a parallel array to keep the ESR really low.  Some of the audio-rated electrolyics for car sound systems may be up to the task, if rather expensive!

Alternatively Ultracapacitors may be suitable - again probably expensive.
[ I won't respond to messages, use the forum please ]

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