i just got a neon sign transformer and it had this little box connected to the primary windings. I have an idea of what it could be (current limiting?) but was not sure. It says on it... neolite neon, OCM-B, Amps:1.5-2.5, Voltage: 240 AC and then all the aproval numbers and whatever. When i tap it, it feels like there is a spring of some sort in there (resistor?). does any one know what it is?
Oh, i didn't notice the capacitor section there. when i tap it, it feels like there is a spring in there or something? It's says its an OCM, does anyone know what that stands for?
It monitors the output voltage, when it rises above a predetermined level, ( as would happen with an open circuit ) it disconnects the output.
This is a safety requirement in most areas, to prevent shock hazard and arcing/fire hazard if the neon tube was broken or a cap came free of the tube.
It often contains a fusible link on a spring, that burns open and the spring ensures the contacts are separated. THis is likely the vibration you noticed.