Attached is a picture of the home built Mini-Oven. Not as pretty but probable just as effective for operating at room temperatures. Three parts inside. A 1N825 ref diode, a small glass thermistor for the temperature sensor and a 1/4 resistor to do the heating. Runs at a nominal 1/8 watt. ws ******** Hi, This is the precision zener diode oven from the 5-1/2-digit DMM V7-34A: http://img714.imageshack.us/img714/9743/ovenizedzener1.jpg http://img249.imageshack.us/img249/7682/ovenizedzener2.jpg Mickle T.