On Thu, 12 Apr 2007 21:39:45 -0700, wrote:

On Apr 12, 8:42 pm, "Homer J Simpson" wrote:
"Arfa Daily" wrote in message



The application is an Elmo school overhead projector. The unit uses an
82v 360W bulb. It looks like the bridge, that is, two sets of diodes
in series with those two sets then in parallel, is in series with the
lamp. When these bridges short, (usually just one diode in the bridge
shorts) the bulbs burn out. In this application it is used as a half
wave rectifier. I thought that perhaps by using a bridge in this
manner they were attempting to get a higher voltage drop across the
unit and less voltage to the bulb as there would be two junction
drops instead of one. However with those junctions then paralleled
with the other diodes maybe it would be a wash. Lenny.

It may be the other way around. I have seen a small bridge used as
protecion. When the big projector bulb fails, there's a big current
spike, blowing the diode.

FWIW on ESP website (Rod Elliot), the 100W guitar amp
project, power supply schematic shows a "protector" bridge.