ot micro amps

fordman · Post by **fordman** » Thu Sep 28, 2006 8:22 pm

does anyone know what micro amps are and what a micro amp meter is suppose to be for? in what application would a person want to read microamps? surely not in a truck or car. some sort of test equipment? if so what kind of test equipment would it be?

turbocharged400sbc · Post by **turbocharged400sbc** » Thu Sep 28, 2006 10:53 pm

it took me a second to figure out what ya was askin'

they arent microamps...it's milliamps
a small measure of AMPs aka current flow

if your using a milliamp meter on a vehicle more than likely you are checking for a key off draw that is higher than 50-75 milliamps which is enough to kill a battery in relativly short time

most EFI cars draw current to keep the memory alive in the PCM (brainbox) as well as for the closk, radio etc.

if this current draw is too large it kills the battery after a couple of nights, however most EFI vehicles will draw up to 3 amps for up to 10-15 minutes (i said SOME) before the car "falls asleep" at which point the draw should be under 75 milliamps

1000 milliamps = 1 amp

1 milliamp = .001 amp

ya dig?0

Regards, James

fordman · Post by **fordman** » Fri Sep 29, 2006 9:25 am

well milliamps is what thermocouplers in furnaces and hot water tanks use. i do know that. this gauge clearly says microamps. if thats the same thing then ok. this gauge has a 3" face and is square it is a zero center scale from 0 - 25 each way negative and positive. it is a mounting type of gauge that would be put in a machine for a permant type of use. as to show micro amps always being used negative or positive. my real question is what would be the aplication of such a meter? it got to be some sort of test equipment or part of some sort of metering system in some test equipment. but for exactly what i dont know.

68F250 · Post by **68F250** » Fri Sep 29, 2006 10:42 am

Milliamps (mA) and microamps (uA) are not the same thing. Milliamps are 1/1,000th of an amp increments and microamps are 1/1,000,000th of an amp increments. In other words a microamp is 1/1,000th of a milliamp.

A +/- microamp current meter like that would probably be used in a piece of electronic equipment where you have to null something, turn the dial until the meter centers. An application I can think of right now is an older analog FM tuner/receiver. The tuning meter is a microamp meter, you tune in the station until the meter reads in the center.

fordman · Post by **fordman** » Fri Sep 29, 2006 11:45 am

ham radio maybe? i had considered that.

kid · Post by **kid** » Fri Sep 29, 2006 11:09 pm

Micro amps is for High end digital equipment to measure the current for control devices.

fordman · Post by **fordman** » Fri Sep 29, 2006 11:13 pm

what type of control devices? sound or ?

kid · Post by **kid** » Fri Sep 29, 2006 11:25 pm

Anything that needs more microamps than a standard chip. TTL driver chips can drive several amps but some drivers are more compatible with very low current devices such as relays of both the magnetic and sold state varieties. They couls be so many different things. We used to have to send TTL outputs to a switching transistor to run a relay to turn on a 12 volt light. You also could use microamp meters to check for stray problems in weapon ignition and fusing circuits where .0000001 A at .002 VAC might trigger a missle launch, while the aircraft is on the deck.