>I am planning to build a high voltage power supply for a tube project, and >I need to create a reference voltage as high as possible >to compare with an output of ~ 400V. Zener diodes only seem to go up to >around 40V, and I was wondering whether it was possible to reverse bias an >ordinary diode with a breakdown voltage in the vicinity of 400V to create >a reference voltage. If I run a (small) constant current backwards >through the diode (probably in the order of micro amps), will this produce >a consistent output, and will the diode be able to withstand this >treatment for long? It will probably work, but I doubt that the stability of the voltage will be good enough. If you need real stability in a power supply I would suggest a solid state reference diode that is something like 7 V. This would be compared to the divided-down output voltage. The 7 V reference diodes are very stable with temperature. This, and a set of stable and accurate divider resistors, will get you a better overall supply. the other thing you can do is bypass the upper divider resistor with a small capacitor. This effectively provides a much higher feedback gain for ac, cutting the ripple down significantly. -- phil
Date: 17 Sep 1998 04:02:19 GMT
Original Subject: Re: Diode back conduction