I want to use a TMP36 temperature sensor, so I thought to transfer the signal through an RJ45 cable. (Is that equal to a cat5 cable? I just used an old ethernet cable)
When I use the sensor next to the MCU (an Arduino) with some common jumper wires, I read a value of about 25oC.
- 25oC equals to 25*10 + 500 = 750mV
When I use the sensor a few meters away from the MCU and transfer the signal with an RJ45 cable, I get readings as low as 3oC.
- 3oC equals to 3*10 + 500 = 530mV
I use an RJ45 cable (8 wires inside) about 1.8m (6ft) long with terminals like these: https://www.sparkfun.com/products/716
I wonder how a voltage drop of about 200mV occures in less than 2 meters of cable? On the same cable (different wires) I transfer the digital signal of a DS18B20 temperature sensor as well as the signal of a DHT humidity sensor, and both seem to work fine.
Is this voltage drop reasonable? If so why? In any case what kind of cable should I use in order to transfer a signal for just a few meters?
Any thoughts would be appreciated.