The Board can be used as a stand alone unit to demonstrate thermionic emissions and used to detect both positive and negative ions in the atmosphere. It can also be used in conjunction with a simple ionization chamber using a tin can to measure radiation particles. A great way to experiment with low voltage valves. You will need to provide 1.5v for the heaters and 6-9 volts dc for the anode volts. Long battery life due to the low currents involved. 

The XE3 break out board allows students to observe thermionic emission and experiment with safe voltages of below 9volts. The LED in the anode circuit can be removed and other measuring devices like moving coil meters inserted. This allows the valve to be incorporated in other detection devices which require a very high input impedance. A fascination device, British made in the era of peak valve technological advancement. This device was the for runner of the transistor. An ammeter can also be connected in the anode circuit by removing the link and connecting a moving coil meter.

About the valves used.

The XE3 is an Electrometer Triode manufactured by Hivac in the UK around 1960.

It is unusual as it requires 0nly 7.5V HT on the Anode. The heater volts of 1.25V requires only 0.015 Amps, that’s just 15milliamps. An XB1 barretter achieves the correct filament volts of 1.25V DC

The grid of the XE3 valve is situated away from the heater and anode connections at the top of the valve to avoid any inter electrode interference. The input is very high impedance and in its day the XE3 was a breakthrough in valve technology. It was the FET in the valve age! The Anode is represented by a red dot.

This can be supplied ready assembled or in kit, bulk Discounts  for school / university projects