); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Tom Clifton <[EMAIL PROTECTED]> wrote: > A question for those that might know (or have an > opinion)... I have in hand an LPRO rubidium reference > that requires 1.7 amps at 24 volts while the oven > warms, dropping to 500ma while it runs.
> Can I parallel three or four 7824 TO220 style 1 amp > regulators with a quarter ohm half watt equalizing > resistor on the output of each one? > At maximum load there would be a quarter volt drop > across the resistors and the LPRO is stated to be ok > running on 16 to 32 volts. Tom, Most of the oven circuits will tolerate a significant sag in potential during warm-up as long as the supply doesn't cut out. I've often run OCXO's and Rb's off a "wimpy" bench supply when my high current bench supply has been otherwise occupied. But if you want more current, the typical way to get a 3-terminal regulator to put out more than spec'ed is to place a big PNP power transistor across the input and output. You'll find the details in the datasheets of many parts (e.g. LM340). Also, check out the National AN-103 app note. It's old but it's still full of useful info. I refer you, at least for a laugh, to page 20 of Linear's AN-83: http://www.linear.com/pc/downloadDocument.do?id=4172 (Despite what others have posted, *some* 3-terminal regulators *can* be paralleled. The LT1083 can be -- checkout the datasheet -- but, nota bene, in the suggested circuit the ballast resistance is on the order of 0.01 ohms, not 0.25 ohms. But it isn't the best idea.) -ch _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.