Table of Contents
Advertisement
CIRCUIT DESCRIPTION
Model
2001
The following circuit descriptions are referenced to the
schematics appearing i n Section 6.
4.3 POWER SUPPLY (PS6)
The PS6 power supply provides three regulated voltages and
an optional "pen-lift'' circuit.
AC POWER
&
RECTIFIER CIRCUITS
A dual-primary transformer allows operation at a line vol-
tage of 115 or 230 volts. AC power is supplied through a 4
wire receptacle from the Front Panel ON/OFF switch.
The transformer is located away from the sweep drive
module t o reduce magnetically coupled line ripple.
Un-
regulated plus and minus voltages are supplied by two full
wave rectifier circuits and filtered by C1 and C7. A 12 pin
plug, mounted t o the printed circuit board, provides access
to three unregulated voltages as well as the regulated +18
-18, and -20V. This plug also accepts a scope horizontal
signal for connection to a Rear Panel connector. The pen-
l i f t switching circuit is also enabled through this plug.
PEN LIFT OPTION
lns~allation of K50 and Rear Panel jacks provides a contact
closure which occurs during the sweep on-time. 0 1 1 is
normally conducting from current supplied through pin 9
of the 12 pin plug. When the base drive t o 0 1 1 is removed,
the relay i s energized by the turn-on of 012. To prevent
early failure of the relay contacts, the relay is only ener-
gized during slow sweep speeds and in the manual position
of the front panel sweep rate selector.
+ I 8 VOLT SERIES REGULATOR
Regulation is provided by IC1 which contains its own inter-
nal reference supply. R9 provides an adjustment t o +18.00
volts.
An external pass transistor, 0 2 , boosts the current
capability, and 0 1 improves the current limiting character-
istics of IC1 by providing amplification before limiting.
The +18 volt supply is protected against reverse voltage by
CR7.
-18 VOLT SERIES -SHUNT REGULATOR
The voltage reference for this supply is obtained from the
+ I 8 volt supply through R20, and R19 provides the feed-
back which is applied to IC2 which provides high gain forc-
ing 0 5 t o maintain a shunt regulated voltage across R13.
0 3 and 0 4 provide the series pass element and are con-
nected a s a compound emitter follower so that the voltage
across R13 is not loaded heavily. Short circuit protection
of
0 5
is provided by
CR8.
Current limiting is provided by
05, when 0 6 conducts sufficiently to forward bias CR9
and CR 10. Reverse voltage protection is provided by CR12.
-20 VOLT SERIES REGULATOR
The reference voltage for the -20V supply is applied to a
differential amplifier, 0 9 and 010, which in conjunction
with 0 8 provides a compound emitter following action
similar to the pass element of the -18V supply.
CR 17 provides reverse voltage protection. Current limiting
is provided by shutting down of the -18 volt supply by 0 7
through CR14 to the base of 05, reducing the reference vol-
tage to the base of 0 9 . This action is helped along by the
conduction of CR13 if the -20 volt supply drops below -18
volts.
4.4 SWEEP RATE (MODULE M 1 H )
M I H SWEEP RATE GENERATOR
This module generates a variable rate square and triangular
waveform.
Front Panel switching provides recurring, trig-
gered, or manual modes. The triangular waveform is a 32
volt peak-to-peak signal with a sweep time variable from
10ms to 100 seconds in four steps.
Retrace time is held
constant at the fastest sweep time of each range. The tri-
angular waveform i s used to provide the sweep drive and
the scope horizontal signals.
The square wave output is a -1 to +15 volt signal whose -1
volt level corresponds t o the sweep time and whose 15 volt
level corresponds to the retrace time. The square wave is
used to provide blanking of the RF output during retrace
time.
Triangular waveformsaregenerated in an integrator, 01, 02,
03, and 04, by applying positive and negative voltage levels
to the integrator input. When the integrator positive ramp
output exceeds a threshold voltage, a bi-stable hysteresis
switch is switched, reversing the polarity of the integrator dc
input, causing the triangular waveform t o start down toward
another threshold. I f the module i s programmed in a recur-
ring mode, the negative ramp will trip the hysteresis switch
producing continuous oscillations.
The hysteresis switch
output is clipped on the negative polarity and is used for
blanking (pin 10).
The symmetrical square wave output from the hysteresis
switch (pin 9) isconnected, through the Front Panel SWEEP
TlME vernier and one of the range determining resistors of
the SWEEP TlME selector switch, to the integrator input
(pin 7). Since the integrator output voltage change is pro-
portional to the input voltage level, the SWEEP TlME ver-
nier provides a sweep time increase by reducing the hysteresis
switch output if the polarity is negative. I f the polarity i s
CIRCUIT DESCRIPTION
The following circuit descriptions are referenced to the
schematics appearing in Section 6.
4.3 POWER SUPPLY (PSG)
The PS6 power su pply provides three regu lated voltages and
an optional "pen-lift" circuit.
AC POWER & RECTIFIER CIRCUITS
A dual·primary transformer allows operation at a line vol-
tage of 115 or 230 volts. AC power is su ppl ied through a 4
wire receptacle from the Front Panel ON/OFF switch.
The transformer is located away from the sweep drive
module to reduce magnetically coupled line ripple.
Un-
regulated plus and minus voltages are supplied by two full
wave rectifier circuits and filtered by Cl and C7. A 12 pin
plug, mounted to the printed circuit board, provides access
to three unregulated voltages as well as the regulated +18
-18, and -20V.
This plug also accepts a scope horizontal
signal for connection to a Rear Panel connector. The pen-
lift switching circuit is also enabled through this plug.
PEN LI FT OPTION
I nstallation of K50 and Rear Panel jacks provides a contact
closure which occurs during the sweep on-time.
011 is
normally conducting from current supplied through pin 9
of the 12 pin plug. When the base drive to 011 is removed,
the relay is energized by the turn-on of 012. To prevent
early failure of the relay contacts, the relay is only ener-
gized during slow sweep speeds and in the manual position
of the front panel sweep rate selector.
+18 VOLT SERIES REGULATOR
Regulation is provided by ICl which contains its own inter-
nal reference supply. R9 provides an adjustment to +18.00
volts.
An external pass transistor, 02, boosts the current
capability, and 01 improves the current limiting character-
istics of ICl by providing amplification before limiting.
The +18 volt supply is protected against reverse voltage by
CR7.
-18 VOLT SERIES - SHUNT REGULATOR
The voltage reference for this supply is obtained from the
+ 18 volt supply through R20, and R 19 provides the feed·
back which is applied to IC2 which provides high gain forc-
ing 05 to maintain a shunt regulated voltage across R13.
03 and 04 provide the series pass element and are con-
nected as a compound emitter follower so that the voltage
across R 13 is not loaded heavily. Short circuit protection
of 05 is provided by CR8. Current limiting is provided by
05, when 06 conducts sufficiently to forward bias CR9
and CR 10. Reverse voltage protection is provided by CR 12.
4-4
Model 2001
-20 VOLT SERIES REGULATOR
The reference voltage for the -20V supply is applied to a
differential amplifier, 09 and 010, which in conjunction
with 08 provides a compound emitter following action
similar to the pass element of the -18V supply.
CR 17 provides reverse voltage protection. Current limiting
is provided by shutting down of the -18 volt supply by 07
through CR 14 to the base of 05, reducing the reference vol-
tage to the base of 09. This action is helped along by the
conduction of CR 13 if the -20 volt supply drops below -18
volts.
4.4 SWEEP RATE (MODULE M1H)
M1H SWEEP RATE GENERATOR
This module generates a variable rate square and triangular
waveform.
Front Panel switching provides recurring, trig-
gered, or manual modes. The triangular waveform is a 32
volt peak-to-peak signal with a sweep time variable from
10ms to 100 seconds in four steps.
Retrace time is held
constant at the fastest sweep time of each range. The tri-
angular waveform is used to provide the sweep drive and
the scope horizontal signals.
The square wave output is a -1 to +15 volt signal whose-l
volt level corresponds to the sweep time and whose 15 volt
level corresponds to the retrace time. The square wave is
used to provide blanking of the RF output during retrace
time.
Triangular waveforms are generated in an integrator, 01,02,
03, and 04, by applying positive and negative voltage levels
to the integrator input. When the integrator positive ramp
output exceeds a threshold voltage, a bi-stable hysteresis
switch is switched, reversing the polarity of the integrator dc
input, causing the triangular waveform to start down toward
another threshold. If the modu Ie is programmed in a recur-
ring mode, the negative ramp will trip the hysteresis switch
producing continuous oscillations.
The hysteresis switch
output is cl ipped on the negative polarity and is used for
blanking (pin 10).
The symmetrical square wave output from the hysteresis
switch (pin 9) is connected, through the Front Panel SWEEP
TI ME vernier and one of the range determining resistors of
the SWEEP TI ME selector SWitch, to the integrator input
(pin 7). Since the integrator output voltage change is pro-
portional to the input voltage level, the SWEEP TIME ver-
nier provides a sweep time increase by reducing the hysteresis
switch output if the polarity is negative. If the polarity is
Advertisement
Table of Contents
