Tektronix RG 501, Инструкция по эксплуатации

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Circuit Descripfion-RG 501
AMPLITUDE attenuates the signal to theoutpul. 078, R8J
and CRSO act as a current limit lor the output stage. l8S
reduces any tendency to oscillate with reactive loads.
090 and 092 form a unity gain, inverting leed-back
amplifier. R90 and R92 offset the base of 090. providing
adjustment lor zero volt starting point of the negative­
going ramp. Open loop gain of the amplifier is set by the
ratio of R95 to the forward resistance of CR89. Closed loop
gain is set by the ratio of R94 to R86. CR89 also
temperature-<:ompenstates the emitter-base junction 01
090. Current limiting for short circuit protection is
provided by R98 in the collector 01 092.
Gate Out Amplifier
044 and 046 buffer the poSitive-going gate output
signal from the Sweep logic IC,
U3O.
R47 is the effective
output impedance at the fronl panel GATE OUT connec­
tor, J45.
Power Supplies
+5
V
Supply.
An unregulated dc voltage from the
mainframe is supplied to the input 01 a three-terminal
voltage regulating IC with built-in short-circuit protection.
The +5 V output is decoupled by C110.
5·4
+15 V
Supply. A 15 volt zener. VRtoo. establishes a
reference voltage at the non-inverting input 01
Uloo,
an
operational amplifier connected in a voltage-follower
configuration. Current 10 the load Issupplied via Rl02 and
an NPN series-pass transistor mounted in the Power
Module. Changes in the load are led back 10 the inverting
input of
Uloo.
A shorl circuit in the load will cause a
voltage drop across Rl02 sufficienllo lurn on 0100which
takes base current from the series-pass, thus shutting it
off. Cl02 decouples the +t5 V supply.
- 15 V
Supply.
A 9 volt, temperature-<:ompensated
zener. VR120. establishes a reference voltage at the non­
inverting input of U12O. an operational amplifier con­
nected in a voltage-follower configuration. The regulated
output voltage of -15 V occurs as a result of the precision
dividers R124 and A126 establishing -9 V at the inverting
Input. Current to the load is supplied via A122 and a PNP
series-pass transistor mounted in the Power Module. load
changes are sensed across
A
124. causing U 120 to change
the base drive to the series-pass until the output returns to
-15
V and the fed-back. inverting input of U120 returns to
-9 V. Short circuit protection Is provided by 0120. As a
voltage drop occurs across A I 22. 0120 will begin to turn
on and take output current from U120 until the series-pass
is turned completely off. C122 decouples the -15 V
supply.