How many temperature sensor

[HodagReef]

How many temperature sensors can the RA handle? I was hoping I could have 6 temperature sensors. Three are for thermal protection of my DIY LED pedants.
Thanks,
Troy

[rimai]

3 without mods...
You can definitely add more if you change the libraries.

[HodagReef]

Thanks Rimai. What kind of mods would be needed? Has anybody else done this? I was thinking to use temp sensors to shut down LED (100w multichip) if the temp was too high (fan failure) by turn down the light and/or shutting off the relay outlet. Other option is to use a temp cutoff switch (12 v DC) to shut off a relay that is inline to the power the drive for LED. Still in the planning phase, so any suggestions would be welcomed.

[rimai]

You would need to splice into the 3 wires on the probe cable to add more probes.
Then, you would still need to modify the libraries though.

[HodagReef]

rimai, what is the maxi amount of probes one should considers splicing into a cable?

[rimai]

It depends on capacitance and how strong your pull up resistor is.
The head unit uses 2k2 as pull up.
I never tested how many though.

[HodagReef]

rimai, thanks for your replies. It’s not hard to figure out that electrical engineering is not my background. So excuse my questions if they’re totally noobish. I do have few other questions relating to the temp probe – Have you consider making an expansion module for temp probes? How long of a cable can you have for a temp probe? I think the probe and RA head unit will be a 25 ft apart.

[rimai]

I think 25ft will be too long.
You will need to have another pull up at the other end, or the signal will degrade and you won't get it to read anything