250 ohm relay... how measure ?

[KB3BYT]

I hooked up a 250 ohm coil on a OEG 5 volt relay, added EMP .. 1N4001 diode and a .01uF disc capacitor to GPIO.0 on
a PIC12C509A.
Relay doing 30 minute ON time and 30 minute OFF time
with plain HIGH and LOW.
I was trying to figure out if the PIC would burn out and tried to measure miliamps BUT my multimeter will not display any values
at all during ON time when wired inline in the relay coil circuit.
I swapped settings on the meter and measure 6 volts DC and the relay does CLICK.
Perhaps my meter is not sensitive enough.
Strictly using just one I/O line so not too worried about any 25ma
maximums..... but I would feel better if the meter actually produced
an acurate reading.

[Melanie]

Time to invest in a new meter for Christmas perhaps...

5v divided by 250 ohms gives 20mA... well inside the 25mA individual pin limit.

[NavMicroSystems]

Originally posted by Melanie
Time to invest in a new meter for Christmas perhaps...


Assuming you have handled your meter correctly, Melanie is absolutely right.

But as any "cheap" Meter today has a at least a 2mA Range, you have probably just missed move the red wire on your meter from the "V" jacket to the "A" jacket to measure current.

You could also have blown the Meters Fuse by trying to measure Voltage in the "Current" setting.

regards

Ralph