My little black box

I spoke with the vendor about my controller. He said I burned out the pre-charge capacitor. He indicated there is a specific sequence I should follow for powering up the components. He also recommended I install a small 12 volt battery to suppliment the DC-DC converter. This battery will prevent current surges.

I designed a circuit to control the startup sequence. It consists of a few relays and a few timer circuits. The contactors, some relays and the controller connect to this box.

I used an analog design to implement the logic. Because of this, the circuit is quite complex. Lots of components. I designed a printed circuit board, and ExpressPCB manufactured the board. I had to modify my design by changing one resistor and adding a diode. But, it seems to work. I'm now designing one using a Microcontroller. I'm beginning to appreciate the difference between analog and digital circuit design.