I am wanting a milli volt generator but i do not have the electrical prints to dos?

Question

the generator is to simulate a K type thermocouple 20 to 50 milli volts max

Answer 1

Cheap and simple solution:
Use a good 1.5Volt battery, connect a 2.7KOhm 1% fixed resistor, and a linear 100 Ohm potentiometer in series across the battery.
Between the center tap and the "bottom" end of the potentiometer, you will get 0 .... 53 milli Volt. Use a knob and scale, and a milli Volt Meter to calibrate it.