Online guide for hobby-level DIY thermocouples?

Do a Google search for [thermocouple tutorial].

You might also search for [Seebeck effect tutorial], since this effect is the cause of the voltage produced by a thermocouple.

You might start with:

Here is another pretty good reference:

That's not a great range in which to be using a thermocouple. Did you have some specific reason to want to use a T/C?

Best regards, Spehro Pefhany

No - just thought that for an analogue meter a device that made (milli)volts all by itself would be likely to keep things simple. What's better?

A thermistor or semiconductor sensor would be simpler to work with. National, for example, has some. Thermistors are nonlinear so a bit harder to work with, but cheaper and more accurate in quantity (not necessarily more stable). A coil of copper wire can be a cheap temperature sensor. A loose coil of thin Pt wire is one of the most stable temperature sensors made. If you are not so fussy, a thin film of the stuff will do. HVAC folks use thin films of base metal stuff like nickel.

Here's a semiconductor sensor that costs around $1 in small quantities:

You need a sensor such as the above in order to be able to use a thermocouple anyway! (for cold junction compensation).

Best regards, Spehro Pefhany