|
Cast iron bath tub full of water with steel and cast iron drain pipes. All great sound conductors. Bendix underwater com system used throat microphone, amplification and small underwater speaker to transmit sound through water that near by divers could hear. Only other place I saw it used was once on 1958 to 1962 sea hunt TV show.
We found only the base and lower side case of each cell in the battery pack. Was using variable voltage DC power supply with volt meter and amp meter to charge the battery pack. It worked but easy to set higher than was safe charge rate.
|