Does anyone know if all for bulbs have to be connected in order for the unit to flash? I move one bulb to the top of the unit (yes wires are soldered correctly) and disconnected the other 3. I'm taking hits but the bulb won't flash.... Thoughts anyone!!! PP

http://rctankhobby.com/PDF/TBU.pdf

Two are in series with another pair in parallel.

Timers, resistance, voltage is all calculated on the forward voltage and current consumption of a LED and the array. Change out one or the schematic and you change the entire circuit. Sometimes it's in the parameters, sometimes it isn't.