I just ordered a DC to HV DC converter (the F40 model, datasheet here: http://www.emcohighvoltage.com/Fseries.PDF [Broken]) from eBay for $50. My intent is to charge capacitors such at the 400V 12,000uF one located here http://www.amazing1.com/capacitors.htm. The converter has output up to 4,000V that is proportional to the input which is up to 12V. So if I wanted to charge the 400V capacitor, would it be best to input around 1.8V to the converter so that its output would be 400V, or would it be better (quicker maybe?) to go ahead and input a higher voltage to the converter, perhaps the full 12V, and simply open the charging circuit once the capacitor has reached 400V? Any help would be much appreciated! Thanks in advance for your time.