The Web is full of examples of fabulous restorations of valve-based televisions and radios that still have cloth wires, paper capacitors, and other components with a certain tendency to spontaneous combustion. Anyone will tell you that it is a very bad idea to try to turn on those devices after so many decades of collecting dust, rust, and moisture, but Professor Carlson from Mr. Carlson's Lab decided (for his entertainment and ours) to take the risk with a battery charger from 1931...
Modern electronics is particularly frustrating for two reasons: its high level of integration makes repairs difficult, and we also have to fight with "black boxes" that have no public documentation. Do you need the circuit of a motherboard or a graphics card? Well, good luck, because the manufacturer will give you nothing to repair their products.
However, things were not like that in the past. Electronics were designed with durability in mind, and it is not unusual to open an old television or radio only to find a copy of the circuit inside, or the list of valves they use. But what happens with a true time capsule? For example, this battery charger from 1931 that Professor Carlson from the Mr. Carlson's Lab channel placed on his workbench. Its repair/restoration is not impossible, but this time, he simply decided to turn it on...
A 93-year-old battery charger in action
The year 1931 is only an "educated guess" for the charger (it appears on the identification plate), and its general design suggests that it is even older. The case also reveals that it is a wall charger, and all its external cables were replaced with slightly more modern versions.
Carlson explains that the charger needs a Tungar rectifier (Tungsten-Argon) and a fuse (both absent). The general design is based on a giant transformer and a reactor, so there is no regulation or "intelligence" here, just an amperage selector and a relatively high no-load voltage (on the order of 20 volts).
After obtaining the Tungar rectifier and the general circuit, the time came to turn it on... and although it seems unbelievable, the charger still works. The cables chill the blood, the sounds of the selector are disturbing and true growls come from inside, but with the help of a (dummy load) it reached its maximum of 7.5A without ending up in orbit. What's next? Restore it, of course!
