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Forum Index : Electronics : power supply

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irishron40
Senior Member

Joined: 22/09/2014
Location: Ireland
Posts: 254
Posted: 12:41am 13 May 2015
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thank you both. great toknow that now.

i did download a list with all vallues and numbers, which is great.#
thx again

ron
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 2437
Posted: 05:18am 13 May 2015
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with electrolytic capacitors, it is best not to use one that is rated at a massively higher voltage that what you are supplying. ie, if you're building a power supply with a 12 volt output, a 400v electrolytic is not a good choice. but a 35v one is likely fine.

this is something specific to electrolytic capacitors - at significantly lower than the rated voltage the effective capacitance (in uF) will be much less than the marked capacitance. so your 330uF 400v electrolytic capacitor, when hooked up across a 12v supply, may only provide smoothing equivilent to (say) 100uF.

please do remember that this applies to electrolytic capacitors only. you are fine using a 100v (or even 1000v) greencap or ceramic capacitor to filter a 12v supply.


cheers,
rob :-)
 
davef
Guru

Joined: 14/05/2006
Location: New Zealand
Posts: 499
Posted: 10:32am 13 May 2015
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When I started my first job on Christchurch in 1970 a workmate quoted the formula Q=CV as a reason not to use electros with a higher voltage rating than needed.

I often wondered how electros could be tested testing electros without any apparent information on the voltage rating.

Since wondering if you could really tell if an electro had lost some of its capacity.

 
irishron40
Senior Member

Joined: 22/09/2014
Location: Ireland
Posts: 254
Posted: 07:26am 14 May 2015
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just like your opinions on meters.


i was thinking of using a dual digital volt/amp meter so i can monitor amps drawn.

and a separate amp meter for current limiter.

would this be a correct setup?


thx

ron
 
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