xformer o/p w/ cap
xformer o/p w/ cap
(OP)
Hello....most likely a rudimentary stupid question I'm just not getting....
Got about a 10v (DC) increase on the output of a rectifier/transformer when I put a cap across it...
Prim 110 I think
Sec. 24vac to rect. dc
how could this be? I believe the cap is rated for 40V.
Got about a 10v (DC) increase on the output of a rectifier/transformer when I put a cap across it...
Prim 110 I think
Sec. 24vac to rect. dc
how could this be? I believe the cap is rated for 40V.





RE: xformer o/p w/ cap
The cap charges to peak VTG.
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: xformer o/p w/ cap
Using meters (especially digital) is often like looking at the world thru a soda straw. Use a 'scope to see the whole picture.
RE: xformer o/p w/ cap
Think about it.. What's coming out of your transformer/ rectifier? A bunch of humpy pulses.. Just what will your specific meter read those as?? You put a cap there and suddenly you have have tiny humps on a DC level. You will get a large increase. Your meter is still going to be wrong. Mine wouldn't be but yours will.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: xformer o/p w/ cap
RE: xformer o/p w/ cap
thanks again.....
Mark
RE: xformer o/p w/ cap
thanks,
Mark
RE: xformer o/p w/ cap
i=C*dU/dT Where i=current [A], C=cap [Farad]
dU= voltage change [V] and dT = time of the change [sec]
If you have 60 Hz with full wave rectification then
dT= 1/120 = 8.333 millisec. If you know your current and
the max. voltage drop, you can calculate it using the Eq.
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: xformer o/p w/ cap
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: xformer o/p w/ cap
RE: xformer o/p w/ cap
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: xformer o/p w/ cap
http
RE: xformer o/p w/ cap
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: xformer o/p w/ cap
When you make C so large that the figure is much greater than 10 then you will gain very little in terms of ripple reduction but pick up a lot of heat.
This is a crude method but yields very workable results.
RE: xformer o/p w/ cap
While I've got your ears...sorry...i coudl use a good link to learn more about swtiching 110vac with relays, and using 110vac relay coils...would a cap(s) placed in series with relay contacts (passing ac)help reduce the bounce or spike voltage?
AC Electronics is like Aikido...The more I do, the less I seem to know :)
RE: xformer o/p w/ cap
To remove switching transients the most common approach is to use a snubber or MOV or Transzorb etc across the load. However another way is to choose a solid state relay that has zero current switching for inductive loads or zero voltage switching for capacitive loads.
RE: xformer o/p w/ cap
RE: xformer o/p w/ cap
RE: xformer o/p w/ cap
Basically, I've got a circuit where I am latching one of the (2) coils with a pushbutton, and run the feedback wire through contacts on the other relay, which is latched with a seperate button (never at the same time).
I don't think solidstate relays are a possiblity...the 'loads' will be almost all inductive....
RE: xformer o/p w/ cap