TM 11-6625-3041-30/TO 33A1-8-908-12
1-26. MULTI VDC (A1) REGULATION (CONT)
Switcher
The high level
Crowbar
Crowbar output
turns on Switcher
Crowbar Q7.
When the
Switcher Crowbar
turns on, it shorts
T2 secondary (ter-
minals 2 and 1).
This short is
reflected into T2
secondary (terminals
5 and 6), which
shorts Q6 base to
emitter and turns
off the Switcher.
The Clock cannot turn off the Switcher because it lacks suffi-
cient power to control the Switcher current, which can be
several amperes.
The Switcher Crowbar remains on only momentarily. Once it
shorts the secondary it no longer has an anode supply sufficient
to keep it conducting.
When the Switcher turns off, the rapid decrease in current
Switcher
induces a high voltage in the secondaries of flyback transformer
T1 .
These secondaries supply power for all four dc supplies,
including the +5V and +10V supplies used for the feedback volt-
age to the negative input to the Error Amp.
1-38