i was always wondering if a relatively high dropping resistor between the reservoir cap and the regulator would slow down the response of the psu when it has to deliver peaks of high current? with higher R's and a health dose of current peaks, you could even underrun the v.reg's minimum in-out voltage drop...
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as for me, i still need to build this multiple supply psu with about 400mA for +45v and 700mA for +24v and +/-20v each, and the dropping R question comes up here, too: i have a huge 28-0-28v xformer, plus another smaller 0-24v one which i could stack up on the former so that i get 28-0-28-52. i'm thinking about using a tl783 for 45v and lm317/337 for the rest. the dc voltages at the reservoir caps would be about 39v and 73v respectively. from 39v down to 20v, the lm317/337's would have to dissipate rouighly 14W each for max current. from 73 to 45, that would be 11W for the tl783. if i mount all these 4 v.reg's on a hefty heatsink of about 40x8x1 cm (psu sits in a rack), should that be fine? or should i rather use dropping R's in order to distribute heat dissipation? if so, can someone suggest values?
oh yeah - the tl783c is rated at 700mA max - will it still deliver 500ma over a 19v drop?
as for the lm317/337: the to220 pack is rated at 15W, will that still be fine, or should i go with to3's, rather? or (stupid question maybe), what about two to220 v.regs in parallel, anyway? never seen such a design though, so i guess that wouldn't work for some reason
hey tekay, why did you change your design from tl783 to lm317?