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Current Transients -- Choke?

I am modulating power to a pump (power on and off) and when I am doing this I am seeing dips in the input voltage to my power regulators (Vin) on other parts of my board.

What is the best approach to guarantee that my Vin won't dip during these current transients caused by my pump? I added some larger input and output capacitors that helped a little but didn't fix the problem. Should I be adding an inductor/choke to help with this? How should I be calculating what type of inductor to use?

Thanks in advance for any info!

Reply to
blanko
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Yes, an inductor can help. But not really if the on/off cycles are longer than a few hundred msec. And be careful since inductors generate nasty spikes upon a load dump.

You can use this tool to see the effect of various sizes of inductors:

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Just pretend the transformer isn't there. Or throw your circuit onto LTSpice. Another trick is to tap the heavy motor current off before the regulators to the other parts of the board.

--
Regards, Joerg

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Reply to
Joerg

Handy site!. I'm just sorting a 6V pos earth, to 12V neg earth, switcher design for a friend who deals in old car radios. Repetitive calcs to home in on a decent wire size and core are not my area of fun, so was a pleasure to just click the buttons and see the results. An ETD44 showed in the list (I've piles of 'em :) and it seems I now need a few more turns :(.

Reply to
john jardine

There you guys in Europe have it easier. Schmidt-Walter's site favors Siemens cores, or now Epcos. Not that popular out here in the Wild West.

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Regards, Joerg

http://www.analogconsultants.com/

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Reply to
Joerg

"blanko"

** Huh ?? So what ?

What do you think voltage regulators are for ??

** Just ignore them.

..... Phil

Reply to
Phil Allison

Just remember that the old tube 6V car radios used positive as well as negative ground (chassis) depending if they were made for the US or for Europe.

Reply to
Robert Baer

The old radios actually had a polarity switch. Most of Europe's cars were negative ground but some French models were not.

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Regards, Joerg

http://www.analogconsultants.com/

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Reply to
Joerg

He doesn't say if the regulators are dropping out with the dips. A low forward drop diode and large cap on the critical supply can serve to decouple the PS dips. I'm running some servo motors from the same unregulated supply as my op amps and used that technique with good results.

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Reply to
default

Set your PC's clock correctly, you idiot.

Reply to
FatBytestard

Here in the US, all of the 6V car radios i had seen were fixed polarity and had no switch. In fact, the construction prevented the use of a switch, as the chassis was used as circuit ground for everything, from input power to plate filter caps to audio output...

Reply to
Robert Baer

5 minutes fast is close enough

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