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This circuit is designed to automatically manage the inrush current drawn by a solid state tesla coil capacitor bank, then quickly discharge the bank after use. Its default state has a discharge lamp connected in parallel with the bank via a NC relay. Once mains is connected it begins to slow charge the main bank through a 20W microwave lamp, while a step down transformer and bridge rectifies it to 12VDC to power the control circuit. The 12VDC supply is used to immediately open the discharge lamp relay as well as begin charging a delay capacitor through a resistor, which is connected to the base of an NPN transistor. Once the delay capacitor has been charged to approximately 0.7V, the transistor begins to conduct, energizing a relay and bypassing the slow charge resistance, applying full voltage to the bank. Once mains is disconnected, the discharge relay closes and reconnects the discharge lamp, indicating the discharge while draining the capacitor bank. The charge delay time is determined by the capacitor and resistor values, set low for simulation since max simulation time is 50mS/S (this results in a 60A spike on changeover, would be adjusted in real life) I’ve included indicator LED’s, green for an active control circuit and redundant reds for bus voltage, since one would assume the bus is dead if the lamp is off, a discharge relay failure could also cause this state.
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