I'm getting four more digital thermostats from Mcmaster Carr. Its a Johnson controls A419 unit. This makes eight units on my place. I want to get spare sensors and I'm thinking this must just be a thermistor??? I see it can be ordered from the maufacturer, but I know it will be a rip off price. Ideas for Digikey, etc.?
A419 thermostat:
P.S. page 10 shows resistance vs. temp of sensor
So, it's 1000 ohm nominal (at 20C or 72F or somesuch), and I make the tempco +7500 ppm/K
Digikey has Vishay items, but with +4100 ppm/K, and only in surface mount (it'd be hard to attach wires). Sounds like you just gotta get them from the manufacturer.
whit3rd wrote in news:06f64cd9-a7ee-41a0-831f- snipped-for-privacy@glegroupsg2000goo.googlegroups.com:
If you strike out at Digikey, don't forget to try Mouser. They carry different stufrf, and I've found a lot of slightly obscure stuff at Mouser:
"PTC" generally means thermistor. Different thermistor materials have slightly different curves, and of course moving the curve up and down is just a matter of changing the thermistor area.
For the little ones that I've used there is no standard. There may be an industrial standard for things like this, though.
This pretty much leaves you with having to shop around, and seeing if you can find a sensor that looks like it has the same curve.
Many years ago, I got good service from RCD.
Kevin Gallimore
Have something to add? Share your thoughts — no account required.
Ask the community — no account required