>> LM293x family (and SOME other regulator families) are specifically >> designed to survive all those things. > > My usual supplier doesn't have these, but does have the LM2940CT - and the > description is very similar > (including mentioning surviving double-battery jump starts!). Do you > happen to know what the difference is > between these two ranges? I have not compared them in detail before. In TO220 the 2940 seems to be 1A max and 2931 is 500 MA max. The 2940 seems to have higher input voltage and superior dropout spec (about half the dropout voltage of an LM2931) but both are comemndably low. I think the 2931 and the 293x seeries in genral are newer ICs with generally superior perfoprmance apart fromt he above figures. Close comparison of data sheets needed. http://cache.national.com/ds/LM/LM2931.pdf http://cache.national.com/ds/LM/LM2940.pdf > I'd always thought that LDO regulators were expensive, but these are the > prices of +5V regs from Maplin: > > 7805 "Value Brand" 39p > L7805CV 39p > L7805CP 79p The CV part is a TO220 package. The CT part is a TO220 variant (they call it TO220 FP) with a slightly WORSE thermal resistance. > LM2404CT 99p Is that REALLY an LM2404 - I imagine that's a typo and meant to be LM2940 Value brand (whatever that is :-) ) CAN be every bit as good as one twice as dear. but that greatly depends on WHY it is cheap, and you often can't tell. It MAY be product which does not meet some critical spec and has been rejected. Or it may be quite OK. For valued projects the LM293X and LM2940 areliable to be worth the little extra in a hostile environment. > Now I wouldn't touch the "Value Brand", but I'm confused about the two > L7805s - there's no hint of the > difference in the catalogue. I would normally go for the third option, > but for 20p extra I think I'll change > my habits! Agreed. RM _______________________________________________ http://www.piclist.com View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist