Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: ed1380 on July 17, 2008, 05:45:06 PM

Title: big capacitor
Post by: ed1380 on July 17, 2008, 05:45:06 PM

i need a motor run capacitor as soon as possible. old one got destroyed. it was rated for 250v 120uf. none of the motor repair shops have had them. neither did grainger. they're all up to about 80uf.

help plz

thx

Title: Re: big capacitor
Post by: dsheller on July 17, 2008, 07:55:47 PM

Use two 60 uF capacitors in parallel?

Title: Re: big capacitor
Post by: Admin on July 17, 2008, 07:58:31 PM

why 250V?

Title: Re: big capacitor
Post by: dsheller on July 17, 2008, 09:01:47 PM

I was curious about that as well... not sure what kind of robot you're going to make that's running off mains voltage.

Title: Re: big capacitor
Post by: ed1380 on July 17, 2008, 10:16:03 PM

its for an air compressor. it runs off 120 but old cap is rated 250. i just might have to do the parralled 60's

Title: Re: big capacitor
Post by: ed1380 on July 19, 2008, 10:21:15 AM

parrallel vs series. how does it work with caps? if i need more uf which way do i do it?

thinking of getting 2 of these http://www.grainger.com/Grainger/items/3GA14

Title: Re: big capacitor
Post by: Admin on July 19, 2008, 10:46:05 AM

Putting caps in parallel is like putting resistors in series, you just add up the values to find the total.

Title: Re: big capacitor
Post by: dsheller on July 19, 2008, 11:32:10 AM

If you get two of those and put them in parallel you'll be fine, but why go for 370V? They'll never continuously see more than 170 V during normal operation....

Title: Re: big capacitor
Post by: ed1380 on July 19, 2008, 04:39:38 PM

thanks. just making sure.

i didnt care what rated voltage. these were the cheapest 60uf ones