For my circuit:
THe zener's cathode goes to the positive supply AND is also the positive voltage terminal of the load. (I'm trying to make almost a negative supply, I guess, that's referenced to the +V of the source).
If I short the resistor...won't that short the zener to ground? If I just open the resistor, where does the base current go?
For your schematic:
Huh, that's different. I was working off of this one presented here:
**broken link removed**
But I am trying to make the load voltage equal to that of the zener's breakdown. It seems that your circuit is dropping the the zener voltage across the NPN and the extra source voltage is being dropped across the across the load, isn't it? I need a regulated voltage that is connected to the high-side of the voltage supply- I think a PNP is needed for that. THe +V of the load is equal to the source's postive voltage, and the load's ground is sitting 15V below the +V of the source., with the extra source voltage being dropped somewhere between the load's negative terminal and the source's ground.
Doesn't your circuit also effectively form a series circuit with the NPN's BE diode, the zener diode, and the load, destroying the zener? I'm thinking the the NPN circuit model here. Or am I forgetting something where the collector current can also control the base current? My understanding right now is that the base current controls the collector current and it does not work the other way around.