We found this assembly in a Radio Craft from May 1942. What we have is a primitive type of light source that used two sticks of coal between which a spark produced light, as with welding machines. It is an experimental or didactic circuit.

We found this assembly in a Radio Craft from May 1942. What we have is a primitive type of light source that used two sticks of coal between which a spark produced light, as with welding machines. It is an experimental or didactic circuit.