ohms load

new york cheech · Post by **new york cheech** » Sat Aug 13, 2005 3:52 pm

does anyone know the ohms load on the 3.3v line?

Post by **gannon** » Sat Aug 13, 2005 6:49 pm

I don't see why that matters, but I get a reading of 2.778 kOhms

new york cheech · Post by **new york cheech** » Sat Aug 13, 2005 11:28 pm

ok thanks, the lady at radioshack said i need to know the ohms load so she can tell me how to wire the adjustable regulator up for 3.3v

pezman · Post by **pezman** » Sat Aug 13, 2005 11:34 pm

youve started like four topics about this one freakin voltage. this kinda stuff can be read on sites and in books. and sounds to me like you need a nice multi-tester/meter.

Post by **gannon** » Sat Aug 13, 2005 11:38 pm

no you don't....
for the lm317 (that's what I assume you want) it's just
Vo = Vref x (1+(R2/R1)) + Iadj x R2
edit: anyways, it looks like you'll need a 240 Ohm resistor and one close to 393.6 Ohms
note that those values are most likely not always accurate. It really depends on the voltage you're inputting to the regulator.

new york cheech · Post by **new york cheech** » Sat Aug 13, 2005 11:48 pm

is it possible u could tell me which resistors i need, cause im a noob at this kinda stuff.
EDIT: im putting in i think 8.4v

Post by **bicostp** » Sun Aug 14, 2005 9:34 am

That's esentially what I said in the F42 thread on this subject.

I think your best bet would be to add 2 1k pots/trimmers and fiddle with the settings until you get the required 3.3v out of it.

MikeJones · Post by **MikeJones** » Mon Aug 15, 2005 7:48 am

what's the part number of that regulator you're getting at the shack?

new york cheech · Post by **new york cheech** » Mon Aug 15, 2005 12:35 pm

lm317t positive

usbcd36 · Post by **usbcd36** » Mon Aug 15, 2005 2:02 pm

Just ask for a regulator and they'll direct you to it. There will be 7812s, 7805s, 7808s and LM317Ts.