BC547 Temp Probe

[More Coffee]

Ive finished building a Thermometer for my Pick-up.
The sensor/probe is a BC547.
Question is ,whats the useful resolution for this type of typical transistor? Most places Ive looked offer 20-70C as a general range.
Essentially if it can reliably given me accurate readings of -30C to 105C I'll be happy,If not I'll switch it out for a LM35..Just means I have to wait to put it in the truck

 

[picbits]

You can also use a 1N4148 diode with very good results.

 

[MikeMl]

Are you using the temperature dependence of the base to emitter voltage? If so, it should work fine over the temperature range you want.... Sometimes the temperature dependence of the circuit used to bias the sensor and amplify its output works against linearity of the entire thermometer. Post your circuit.

 

[More Coffee]

I just used this schematic,(pg3) part for part..only I used 1% resistors through out.

https://www.electro-tech-online.com/custompdfs/2013/01/k2.pdf