Relay Board 12 volt Different ? R1 10K 1K ?

Projects Discussion and Showcase Home Automation and Networked Objects
#1

I am using some 12 volt relay boards from ebay that do not seem to match schematics I can find , Including what came with it.

I have attached what I have.

The boards come with the input R1 resistors as a 10k value. With an Arduino Digital High this gives around 190 u amps through the indicator LED and the chip emitter diode. This is not enough to saturate the output transistor and results in only 6.7 volts across the coil.

What I wound up doing is replacing the R1 resistors with 1k. This gives 1.90 ma through the indicator LED and the chip emitter diode. And fully turns on the relay.

:confused:
Has anyone else run into this ?

12v relay.jpg
12v relay.jpg2010×1434 393 KB

#2

10K does seem way too high- its possible that the manufacturer simply used the wrong part or it was intended for a much higher voltage.

#3