substitute d/c cap. for a/c?

[Richard]

I blew out a 1 mfd 120v.a/c cap. in my OLD generator automatic switch and
can't find a replacement. I was wondering what I can use for a substitute?
The original is a can about 7/8"D. X 1-1/2" long, wound tinfoil
inside(was) and a lead out each end. Would a 1 mfd. 400v.d/c work? what
type?
T.I.A.

 

[Michael A. Covington]

I think the main thing is that it needs to be a capacitor that isn't
sensitive to polarity, i.e., a plastic film capacitor of some type rather
than an electrolytic. Plastic film capacitors don't have positive and
negative ends. I suggest one that is rated at 250 volts.

The maximum voltage rating might still be expressed as DC volts; that
doesn't make it a DC capacitor.

"Richard" <rtamm@personainternet.com> wrote in message
news:10bbu61nbulq298@corp.supernews.com...

I blew out a 1 mfd 120v.a/c cap. in my OLD generator automatic switch and
can't find a replacement. I was wondering what I can use for a
substitute?
The original is a can about 7/8"D. X 1-1/2" long, wound tinfoil
inside(was) and a lead out each end. Would a 1 mfd. 400v.d/c work? what
type?
T.I.A.

 

[Dave Platt]

In article <q-qdnSjpP4hymivd4p2dnA@speedfactory.net>,
Michael A. Covington <look@www.covingtoninnovations.com.for.address> wrote:

I think the main thing is that it needs to be a capacitor that isn't
sensitive to polarity, i.e., a plastic film capacitor of some type rather
than an electrolytic. Plastic film capacitors don't have positive and
negative ends. I suggest one that is rated at 250 volts.

The "AC" rating might also indicate that the cap needs to be able to
tolerate high ripple currents (i.e. have low internal losses, or be
resistant to degradation due to the heat generated by its losses)
and/or might need to be safety-rated for connection across power mains
(e.g. the X2 safety rating used these days).

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Michael A. Covington]

"Dave Platt" <dplatt@radagast.org> wrote in message
news:10bc5brhineog79@corp.supernews.com...

In article <q-qdnSjpP4hymivd4p2dnA@speedfactory.net>,
Michael A. Covington <look@www.covingtoninnovations.com.for.address
wrote:

I think the main thing is that it needs to be a capacitor that isn't
sensitive to polarity, i.e., a plastic film capacitor of some type rather
than an electrolytic. Plastic film capacitors don't have positive and
negative ends. I suggest one that is rated at 250 volts.

The "AC" rating might also indicate that the cap needs to be able to
tolerate high ripple currents (i.e. have low internal losses, or be
resistant to degradation due to the heat generated by its losses)
and/or might need to be safety-rated for connection across power mains
(e.g. the X2 safety rating used these days).

Good point. He should use a capacitor that is designed for use with
line-powered AC motors, for safety's sake.

 

[Watson A.Name \"Watt Sun]

Richard wrote:

I blew out a 1 mfd 120v.a/c cap. in my OLD generator automatic switch and
can't find a replacement. I was wondering what I can use for a substitute?
The original is a can about 7/8"D. X 1-1/2" long, wound tinfoil
inside(was) and a lead out each end. Would a 1 mfd. 400v.d/c work? what
type?
T.I.A.

Use an X2 rated capacitor. You can find X2 caps in old AT power
supplies. THey're usually something like .47 uF or 470 nF, at 240VAC.
You could put two in parallel for about 1 uF.