three terminal volt regulator

Generally, 5 volts is 5 volts. The price shouldn't be a major concern unles s you are building a million units. In, ground and out.

ipate 2.5 watts at no load. Not efficient but probably the cheapest option.

Between the LM340XX-5 and the 7805, I'd get whichever is cheaper.

All of the regulators of that type are the same as far external circuits go. As long as the voltage and current ratings are the same or greater, just go with whatever you want.

Just do not interchange the positive ones and negative ones.

That should have been the voltage the same and the current same or greater.

ess you are building a million units. In, ground and out.

ssipate 2.5 watts at no load. Not efficient but probably the cheapest optio n.

Thanks, I ordered the cheaper 7805... just wondering.

George H.

???

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     ?

** So they all say ....

** TO220 pac 7805s are rated at 1.5 amps, long as chip dissipation is not exceeded.

IIRC, obsolete TO202 pac LM341s were 0.5 amp.

** IME, no. Some devices have both numbers printed on them.

FYI: had to replace a couple of 7815s the other day in a dBx dual 31 band graphic. The regs were full pac versions with NEC brand name.

After warming up a little, both examples shut down completely.

... Phil

As long as you're using an electrolytic cap on the output, the two ought to be equivalent, but they might behave differently with big ceramic or alpo caps, whose ESR is very low. For instance, the ON Semi TLV431 is far more prone to oscillate than the TI or Diodes versions.

National used to label its TO220 regulators with both LM7805 and LM340-5 on the same part--I still have some like that.

With old parts like that, it's hard to know if what TI is selling these days is the old TI part or the old National part or what.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

Huh, Thanks... I'll order some of those then. (The Onsemi parts are going away.)

George H.

As long as it doesn't oscillate.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

If your budget can stand it, you might want to consider a switching mode re gulator. Some are three-terminal drop-in replacements for the TO-220 devic es.

If you are a hardware hacker (literally), you can cannibalize one from a US B car charger. Here in Silicon Valley, Fry's Electronics sometimes sells t hem for under a dollar. This may not work reliably if your unregulated sup ply is over 18V, but should work fine if it is 15V or less.

Thankyouthankyouthankyou! I have a function generator that at 12V will bake the 78L05 TO-92 cased regulator; the switchmode .5A unit should work a treat in its place so I don't have to have a second PSU just for it, when working on speedometers for my cars!

RwP