5V reference

momostallion · Post by **momostallion** » Mon Jul 07, 2014 3:26 pm

Hello,

Just a quick question about the +5V reference output from the RCP unit. Is that safe to drive multiple analog sensors (maybe 4 sensors) from that single 5V lead?

Thanks.

toga94m · Post by **toga94m** » Tue Jul 08, 2014 2:49 am

From the schematic on Github, the VRef output is internally protected by a 50mA PTC (self-resetting fuse) so as long as you don't go over 50mA total, you can drive whatever you want. Current is figured by volts/ohms, so at 5V out, if you've got a 1k throttle position sensor, that's 5mA = 0.005A. You could run 10 of those and be right at the limit. If your sensor is a 10k load, that'd only be 0.5mA, and you could run 100 of them.

So the answer is, it depends on your sensors.

momostallion · Post by **momostallion** » Tue Jul 08, 2014 3:13 pm

sounds good. thank you!

as far as getting the resistance of a sensor, if that wasn't part of the specs, i should just be able to measure it using a multimeter right?

toga94m · Post by **toga94m** » Tue Jul 08, 2014 6:54 pm

If it's a simple position sensor (linear or rotary potentiometer) then an ohmmeter will work. For smart sensors (temperature, pressure) you'll need power/current specs from the vendor.