Hagerman Audio Labs VACUTRACE User manual

VACUTRACE
Vacuum Tube Curve Tracer
Made in USA

VACUTRACE Vacuum Tube Curve Tracer
2
Copyrights & Trademarks
©Copyright Hagerman Audio Labs 2012. All rights reserved. No part of this
document may be photocopied, reproduced, or translated to another language
without the prior written consent.
Disclaimer
The information contained in this document is subject to change without notice.
Hagerman Audio Labs shall not be liable for errors contained herein or for
consequential damages in connection with the furnishing, performance, or use of this
material.
Warranty
Hagerman Audio Labs warrants this product free of defects in materials and
workmanship for a period of 10 years (90 days on tubes). If you discover a defect,
Hagerman Audio Labs will, at its option, repair or replace the product at no charge to
you provided you return it during the warranty period, transportation charges
prepaid to Hagerman Audio Labs. This warranty does not apply if the product has
been damaged by negligence, accident, abuse or misuse or misapplication, has been
damaged because it has been improperly connected to other equipment or has been
modified without the express written permission of Hagerman Audio Labs. This
warranty is limited to the replacement or repair of this product and not to damage to
equipment of other manufacturers. Any applicable implied warranties, including
warranty of merchantability, are limited in duration to a period of the express
warranty as provided herein beginning with the original date of purchase and no
warranties, whether express or implied shall apply to the product thereafter. Under
no circumstances shall Hagerman Audio Labs be liable for any loss, direct, indirect,
incidental, special, or consequential damage arising out of or in connection with the
use of this product.
Hagerman Audio Labs
PO Box 61911
Honolulu, HI 96839
808-383-2704 (voice)
www.haglabs.com

VACUTRACE Vacuum Tube Curve Tracer
3
Description
The VacuTrace is a unique piece of laboratory test equipment that converts your
analog oscilloscope into a full-features vacuum tube curve tracer. This powerful and
flexible combination accurately sweeps the characteristic curves of diodes, triode,
tetrodes, and pentodes in real-time. A special A/B comparison mode allows perfect
tube matching by overlapping both sets of curves. A digital readout displays plate
and grid bias voltages, cathode current, transconductance gain, and output
conductance (1/rp).
Specifications
Item Specification
Plate Voltage 0V to 380V @200mA
Cathode Current 0mA to 100mA (200mA in 2A mode)
Grid Step Sizes 0.5V, 1V, 2V, 5V, 10V (8 steps) @5mA
Plate Power 20W peak
Screen Voltage 100V to 300V @25mA
Transconductance 0.1mA/V to 20.0mA/V
Output Conductance 0.001mA/V to 2.000mA/V (1000k to 500 ohm)
Basic Accuracy 2% voltage and current, 5% conductance
Output Signal Gains Plate/Screen: 10mA/V
Grid: -50mV/V
Cathode: 40mV/mA
Intensity Modulation 5V TTL levels, low on, high off
Heater Supplies 6.3V @5 amp
5.0V @3 amp
Socket Adapter Cards Dual Triodes: 8 and 9 pin
Pentodes: 8 pin (A and B)
Power: 5V Diodes and 2A3/300B
Blank: (wire up you own socket)
Input Voltage 120Vac or 240Vac, 50W
Fuse 1 amp 5x20 slo-blo

VACUTRACE Vacuum Tube Curve Tracer
4
Socket Adapter Cards
Socket adapter cards are employed to accommodate various tube pinouts. These
cards plug onto the connector at the top of VacuTrace and are held in place by four
wing nuts. They are built to be rugged and quickly swapped with one another. A
socket adapter card must be installed before a vacuum tube can be tested. Standard
cards included with VacuTrace are:
• Dual 8 and 9 pin triodes (12AX7A/6DJ8, 6SN7)
• Octal pentode power tubes (6L6GC, KT88)
• Power triodes and diodes (2A3/300B, 5Y3)
• Jumper (any 7, 8, or 9 pin tube)
Connections
Connecting a VacuTrace is simple. Use the BNC cables provided to connect the X, Y
and Z outputs to your oscilloscope. Note, not all oscilloscopes have intensity
modulation. This is ok, but makes it more difficult to determine which curve belongs
to which tube in A/B comparison mode.
1. Connect Xto channel 2 (horizontal) on your oscilloscope.
2. Connect Yto channel 1 (vertical).
3. Connect Zto the intensity modulation input, usually located on the rear.
4. Connect the ac power cord.
That’s it, install a socket adapter card and you are ready to go. Be sure to set your
oscilloscope to XY mode. Also, initially set both channel attenuators to 0.5V/division.

VACUTRACE Vacuum Tube Curve Tracer
5
Operation
Front Panel
The controls have been laid out and spaced for easy and intuitive operation. Be sure
to select standby mode before changing tubes or socket adapter cards.
Control/Indicator Description
Tube Select Sets the operating mode and chooses which tube to sweep.
There are two tube circuits, Aand B, which define the sections
within a dual tube (or left and right sockets on the octal power
pentode adapter). Stby mode shuts down all signals to the
sockets, including heater supplies. Selecting Aor Btests just
that tube. A/B mode alternately tests both tubes resulting in
overlapped curves and is ideal for matching tubes. 2A mode
doubles current and power capability by shunting the cathode
current sense resistors together.
Grid Steps Selects the step size (gain) for the grid amplifiers. There are
always eight steps starting at 0V.
Voltage This is the main limit control and sets the maximum value of
plate voltage for sweeping. When the limit is reached, the
plate voltage ramps back down to 0V initiating another cycle.
Current Sets the maximum value of cathode current for a sweep.

VACUTRACE Vacuum Tube Curve Tracer
6
Power Sets the maximum peak power dissipated by the tube’s plate
during a sweep.
Rate/Offset This is a dual function control. While sweeping it acts as sort
of a sweep rate adjustment. It offers a compromise between
accuracy and visual flicker. In Hold mode this becomes an
offset adjustment for the grid bias voltage.
Sweep/Hold Sets the operating mode between sweeping curves and taking
measurements. In Hold mode the 3½ digit LED display is
turned on and reads the value of the measurement selected by
the Output control.
Output Selects the measurement to be read in the display. Normally,
tube curves are swept in the gp mode, but the gm mode can
also provide useful information.
Triode/Pentode Operates the tube as either a triode or pentode. The screen is
tied directly to the plate in triode mode.
Screen Adjusts the screen voltage when in pentode mode.
Status LED indicates the present operating mode or condition. When
in standby it is red. During normal operation it is green. If
flashing yellow, then VacuTrace is experiencing an overload
condition.
Caution LED lights up yellow when a voltage greater than 70V is
present on the output connector.
Rear Panel
The rear panel holds the ac mains input/fuse holder connector, on/off power switch,
and three output signal BNC connectors. The outputs are labeled X, Yand Zand
connect to your oscilloscope by the BNC cables provided. See Chapter 1 for correct
wiring.
Socket Adapter Cards
Some of the socket adapter cards contain switches. These are for heater voltage
selection or, in the case of a diode, to choose which plate is operating (pin 4 or pin
6). The heaters of a 12AX7 type tube are run in parallel at 6.3V (set switch to
12.6V). All heaters are ac. The wing nuts are connected to chassis ground. There
are two tube circuits, Aand B, which allows for tube matching. The output connector
has the following pinout:

VACUTRACE Vacuum Tube Curve Tracer
7
Pin # Signal Description
1 PLATE Plate (common to A and B)
2
3 IKA Cathode (A)
4 GRIDA Grid (A)
5 +6H Switched 6.3V heater power
6 5CT 5V heater center tap, connected to cathode
7 +5H Switched 5V heater power
8 SCREEN Screen (can be switched to plate, common to A and B)
9
10 IKB Cathode (B)
11 GRIDB Grid (B)
12 -6H 6.3V heater return
13 GND
14 -5H 5V heater return
On the Duals card, both sockets use Aand Bcircuits (use only one tube at a time).
On the Pentodes card, the left socket uses A, right B. Both sockets on the Power
card use the Acircuit.

VACUTRACE Vacuum Tube Curve Tracer
8
Generating Curves
Setup
The most common use of VacuTrace is to sweep the characteristic curves of a
vacuum tube. There are two ways to display curves, cathode current vs. grid
voltage, and cathode current vs. plate voltage. Most users are familiar with
published operating curves as shown below (which were actually generated using a
VacuTrace).
While in standby mode, install your tube. Set the Voltage limit to minimum, the
Sweep/Hold switch to sweep, and Output to gp. Adjust the Current and Power limits
to appropriate levels. Set the attenuator controls on your oscilloscope to the desired
gain levels as given in the following table.
Output Oscilloscope Actual
Plate/Screen 1V/div
0.5V/div 100V/div 50V/div
Cathode 0.5V/div
0.2V/div
0.1V/div
12.5mA/div
5mA/div
2.5mA/div
Grid 1V/div
0.5V/div
0.2V/div
20V/div
10V/div
4V/div
Make sure the oscilloscope is set to XY mode and the spot is positioned in the lower
left corner (you may need to use the horizontal position control instead of the
channel 2 offset). This point is defined as 0mA and 0V. Now turn the Tube Select to
Aand wait 10 to 30 seconds for the heater to warm up. Slowly increase the Voltage
limit and you will see curves starting to form. Adjust the Grid Steps and other

VACUTRACE Vacuum Tube Curve Tracer
9
controls as necessary until you have a full set of curves and the tube is running
safely within its ratings.
Limits
Three sweep limit controls are provided to prevent tube damage and allow you to
adjust the way you want the curves presented. The triode curves shown above are
power and voltage limited. The A/B mode curves shown below are both current and
voltage limited. Sometimes you will want to combine all three.
Modes
Tube matching is accomplished using the A/B mode. VacuTrace automatically
alternates sweeps between tube Aand tube Bdisplaying both sets of curves
simultaneously. Differences in tubes are readily apparent and it becomes obvious
that single point matching (such as current at a given bias) is insufficient. The Z-
axis intensity control modulates the Btube so that its curves appear dotted.
Switching to 2A mode connects both cathode sense resistors together thereby
doubling the current capability to 200mA. Note that while in Aor 2A mode, the B
tube is cutoff by applying –70V to its grid. And, of course, vice versa.

VACUTRACE Vacuum Tube Curve Tracer
10
Sweep rate is adjusted by the Rate/Offset control. Use this to reduce flicker in the
display. Setting the Triode/Pentode control to pentode enables the Screen control.
It is best to start at 100V and work your way up.
You may switch modes at any time and set controls to any position in any
combination without causing damage to VacuTrace.
Transfer Function
By switching the Output to gm the oscilloscope display changes to current vs. grid
voltage. You will probably have to readjust the attenuator on the X-axis to get a
better aspect ratio. This unusual set of curves defines the transfer function for a
given plate voltage. However, you must insure that neither the Current nor Power
limit controls are involved. Drawing imaginary lines connecting each peak yields the
input-to-output transconductance transfer function. Linearity of the tube is
demonstrated by the spacing from peak to peak.

VACUTRACE Vacuum Tube Curve Tracer
11
Measurements
Hold Mode
Tube measurements are taken by switching to Hold mode. By doing so, the plate
voltage goes to the Voltage limit setting and the grid voltage goes to the Grid Steps
setting plus the offset from the Rate/Offset control. This determines the bias point
to operate the tube. You will also notice the 3½ digit LED display is enabled.
Setting the Output control to Vs reads the present screen voltage, or if set to triode
mode, plate voltage. Changing to Vg reads grid voltage. Use the combination of
Grid Steps and Rate/Offset controls to obtain any grid voltage from –0.5V to –70V.
Once the desired operating point is dialed in, switch Output to Ik to read the
resulting cathode current in milliamps.
Ratios
VacuTrace provides dynamic ratio measurements of great value to circuit designers,
namely transconductance gain and output conductance.
Transconductance (gm) mode measures the ratio of output Ik divided by input Vg
given in mA/V. The modulation of signals and division is all accomplished with
analog circuitry. You can see the modulation on the oscilloscope, centered about the
chosen operating point.
Similarly, gp measures the output conductance (1/rp) of the tube. It is the ratio of
output Ik divided by input Vp given in mA/V. Again, the modulation, or portion of
the curve being measured is visible in the display. VacuTrace always provides a
clear picture of what is being measured.
Other standard tube parameters are calculated by:
p
m
p
p
g
g
g
r
=
=
µ
1

VACUTRACE Vacuum Tube Curve Tracer
12
Technology
Generating Curves
VacuTrace sweeps the characteristic curves of a vacuum tube by applying plate,
screen and grid bias voltages and measuring the resulting cathode current. A low
value resistor shunts the cathode to ground converting the current into a voltage
that is then amplified and sent to the Y channel of the oscilloscope. The plate
voltage is ramped up and down and (an attenuated copy) is sent to the X channel,
thereby “drawing” a curve on the oscilloscope’s display. The update rate determines
image flicker and if fast enough, the curves will appear continuous.
A set of curves is formed because the grid voltage changes to a new value every
time the plate reaches 0V. The grid is stepped to eight different levels starting at
0V. The oscilloscope photo below shows the relationship between plate and grid
voltages.
The peak plate voltage is determined by any of the three limit controls. When one of
these limits is reached the ramp is reversed back towards 0V. Normally the voltage
limit control sets the peak voltage. But often you may want to limit either peak
current or peak plate power, both of which can occur prior to the voltage limit. This
capability is to prevent tube damage.
Taking Measurements
Both static and dynamic measurements are done in Hold mode. Switching to Hold
mode turns off the sweep and sets the plate voltage to the present limit setting
(regardless of current and power limits).
Static voltages and current are measured using a standard analog-to-digital
converter (DMM) IC.

VACUTRACE Vacuum Tube Curve Tracer
13
In gm (transconductance) mode, a 625Hz modulation is added to the grid output.
The dynamic peak-to-peak grid voltage is used as the reference for the LED analog-
to-digital converter and the resulting cathode current modulation (just the ac
component) is used as the input. This creates an analog divider circuit to calculate
∂Ik/∂Vg, which is transconductance gain. Similarly, in gp mode, the plate voltage is
modulated and dynamic cathode current measured to determine output conductance.

VACUTRACE Vacuum Tube Curve Tracer
14
Miscellaneous
Tube Life
Always set the plate voltage limit to minimum before coming out of standby. Do not
turn up the plate voltage until the heaters have warmed up, otherwise you could
cause cathode-stripping damage.
Be careful not to exceed any of the tube’s maximum operating specifications.
VacuTrace can deliver a lot of voltage, current and power to a tube. Small signal
types such as a 12AX7 are vulnerable to such overdrive.
It is not necessary to turn off VacuTrace when swapping tubes or socket adapter
cards. That is what standby mode is for. All signals to the output connector are shut
off in standby and it is safe to change tubes.

VACUTRACE Vacuum Tube Curve Tracer
15
Troubleshooting
Problem Possible Causes/Solutions
Does not turn on. Power cord not plugged in or fuse blown. Power switch
on rear panel must be turned on.
Tries to turn on but does
not operate correctly. AC input voltage selection on wrong setting.
LED display does not
work. VacuTrace must be in Hold mode.
Curves not generated. Faulty tube. Oscilloscope not in XY mode or set up
improperly. Heater not warmed up yet. VacuTrace in
Stby or Hold modes.
Oscilloscope display is
backwards. XY cables are reversed.
Curves keep
disappearing. VacuTrace is in an overload condition, lower the plate or screen voltage or remove fault.

A A
B B
C C
D D
E E
F F
G G
5 5 4 4 3 3 2 2 1 1
AC Voltage Select Board
N
Ac Switch Ac Input
Blu Blu/Yel Brn/Yel Brn Blk Blk/Red Wht/Blk Wht
E
Blu Brn
Gry Red Vio Red/Yel Red Yel Yel Yel/Blk Grn Grn Grn/Yel
Grn/Y Grn/Y
LL
ES
Blu/Yel Brn/Yel Blu Brn Blk Blk/Red Wht/Blk Wht
100V 110V 120V 200V 220V 240V
NC NC
NC NC NC NC
NC NC NC NC
NC NC NC NC
NC NC NC
NC NC
NC
NC NC NC
NC NC
NC SSS
SSS
LLL
LLL
LLL
NNNNNN
NNN
AC Voltage Select
N
275Vrms @150mA 5Vrms @3A
6.3Vrms @5A
6.2V @1A
1.275V
This document contains proprietary information and except with written permission of Hagerman Technology LLC such information shall not be published, or disclosed to others, or used for any purpose, and the document shall not be copied in whole or in part. Copyright Hagerman Technology LLC 2000. All rights reserved.
-5.65V @14mA
n/a A
VacuTrace: Power Supply Hagerman Technology LLC P.O. Box 26437 Honolulu, HI 96825
18Tuesday, August 22, 2000
Title Size Document Number Rev Date: Sheet of
D1 1N4007 C2
100u 450V
C4 10n 500V
D3 1N4007
D2 1N4007
C3 100u 100V
C8 22u 10V
C6 10m 10V
T1 370FX
C10 470u 10V
C11 22u 10V
ICL7660 U2
V+
8
C+
2OUT 5
GND
3
C-
4
S
6
C7 10u 10V
C9 470u 10V
C1 10n 500V
C5 100n 50V R1 4k7 1/2W
R3 4k02 1% R6 1k 1%
J32 J33 J34
J36
J35
J25 J26 J27 J28 J29 J30 J31 J23 J22 J24
J11 J12 J14 J15 J16 J17 J18 J19 J20 J21 J13
D4 1N4007
D7 1N4007 D5 1N4007
D6 1N4007
R2 10 R4
10
TP1
R5 100
LM2941
FB 1
IN
4OUT 5
GND
3
/EN
2
TP2
TP3
ICL7660 U19
V+
8
C+
2OUT 5
GND
3
C-
4
S
6
C50 10u 10V
+400V
-70V
+5H -5H 5CT +6V
-6V
10kHz
-6H +6H
+8V

A A
B B
C C
D D
E E
F F
G G
5 5 4 4 3 3 2 2 1 1
0V to 400V @200mA
10mV/V
GDS
200mV/W
-5.65V
n/a A
VacuTrace: Plate Amp Hagerman Technology LLC P.O. Box 26437 Honolulu, HI 96825
28Tuesday, November 14, 2000
Title Size Document Number Rev Date: Sheet of
+400V
+6V
-6V
+6V -6V +6V
+6V
+6V
+6V
-6V
-6V
+6V
-6V
+6V
-6V +6V
C14 100p LM358
U3B
5 6
7
4 8
Q3 ZTX558
Q6 2N3904
Q8 ZTX458
Q9 2N3904
J1 Socket Board
1 2 3 4 5 6 7 8 9
10 11 12 13 14
R19 16 1/2W
R7 1k
R13 100k 5W
R31 2k
R35 100k 1%
R42 100k 1%
R39 4k99 1%
R15 249k 1% 1/4W R10 249k 1% 1/4W
R33 249k 1% 1/4w R34 249k 1% 1/4w
R24 6k49 1%
R22 2k
Q1 2N3906
C16 100n
C17 100n
C13 10u 10V
R25 100k 1%
R43 100k 1%
U5B LM13700
11 16
9
1012
13 15 14
6
Q5 IRF820
R18 4k7
R14 470
Q4 IRF820
R20 16 1/2W
R17 10k R12 470
D8 1N5237B 8V2
R9 10k
Q2 ZTX558
R11 100k
C12 2p2 500V
R8 3R0 1/4W
Q7 ZTX558
R16 100k
R27 6k49 1% R29
20k0 1%
R23 100
LM358 U4A
3 2
1
4 8
R38 10k
R30 100 R26 2k
R28 47k
R21 10k0 1%
R32 10k0 1%
LM393 U6B
5 67
4 8
LM393 U6A
3 21
4 8
R40 100 C15
1u
R41 402k 1%
R36 402k 1%
R37 470k
R45 402k 1% R44 402k 1%
D10 1N4148 D11 1N4148
D12 1N4148
R47 10k
R46 100k 1%
LM358 U3A
3 21
4 8
TP4
D33 1N5226B 3V3
Q36 ZTX458
R164 10k
R165 10k
Q35 ZTX458
Q37 2N3906
Saturate
Vplate
Plate Screen GridA GridB +6HR 5CT +5HR -5H
IkA IkB
Caution
Plate
-6H
Shutdown
Pmod
Xscreen IkA
IkB
Standby
Green
Red
+8V
Ramp
Bleeder

A A
B B
C C
D D
E E
F F
G G
5 5 4 4 3 3 2 2 1 1
SCREEN
TRIODE/PENTODE
1 3 2
4 6 8
R L
CW
10mV/V
100V to 300V @25mA
n/a A
VacuTrace: Screen Amp Hagerman Technology LLC P.O. Box 26437 Honolulu, HI 96825
Custom
38Friday, December 22, 2000
Title Size Document Number Rev Date: Sheet of
+6V
-6V
+400V
Q12 ZTX458
R49 1M
P2
J2
J2
P2 S1
LM358 U4B
5 67
4 8
R51 470k 1/4W
R48 22k 1W
R52 220 1/4W R55 249k 1% 1/4W R57 249k 1% R59 4k99 1%
Q10 IRF820
D13 1N5237B 8V2
R54 100
R56 100
C18 3u3 450V
R58 10k
TP5
R166 10k
R172 100 1/2W
D13 1N4761A 75V 1W D13 1N4761A 75V 1W D13 1N4761A 75V 1W D13 1N4761A 75V 1W
ScreenBleeder
Plate
Vscreen
Shutdown Xscreen

A A
B B
C C
D D
E E
F F
G G
5 5 4 4 3 3 2 2 1 1
n/a A
VacuTrace: Grid Control, Modulation Hagerman Technology LLC P.O. Box 26437 Honolulu, HI 96825
48Friday, August 18, 2000
Title Size Document Number Rev Date: Sheet of
+6V
+6V
+6V
+6V
+6V +6V +6V +6V +6V +6V
+6V
+6V +6V
U8B CD4520B
CK
9EN
10
R
15
Q3 14
V+
16
V-
8
Q2 13 Q1 12 Q0 11
U7D CD4081B
14
11
7
13 12
U9A CD4001B
14
3
7
2 1
U8A CD4520B
CK
1EN 2
R
7
Q3 6
V+
16
V-
8
Q2 5 Q1 4 Q0 3
U9C CD4001B
14
10
7
9 8
U9D CD4001B
14
11
7
13 12
U7C CD4081B
14
10
7
9 8
U9B CD4001B
14
4
7
6 5
U7B CD4081B
14
4
7
6 5
U7A CD4081B
14
3
7
2 1
C22 1u C23 1u
R61 100k 1% R62
10k0 1%
R60 2M
R167 10k R168 10k
Bottom Grid2
Grid1 Grid0
ClockAB
Grid3
Hold
10kHz /Gp
Diff
Pmod
Gmod
Single
/Gm

A A
B B
C C
D D
E E
F F
G G
5 5 4 4 3 3 2 2 1 1
0V to -70V @5mA
ECB
2 5
4
GRID STEPS
5
0.5 1 10
123
0V to -70V @5mA
ECB
2 5
7
GRID STEPS
6
0.5 1 10
10 9 8
5V 2V 1V 0.5v
1.2V
n/a A
VacuTrace: Grid Amps Hagerman Technology LLC P.O. Box 26437 Honolulu, HI 96825
58Monday, October 09, 2000
Title Size Document Number Rev Date: Sheet of
+6V
+6V
-70V
-6V
+6V
+6V
+6V
-6V
+6V +6V
C32 220p
Q13 2N3906
Q15 2N3906
Q19 MJE340 Q23 MJE350 D20
1N4007
Q25 MPSA42
Q27 2N3904
R69 100k 1% R72 200k 1% R75 402k 1% R67 402k 1% R63 60k4 1% R88 100 R93 100
R97 4k7
R77 649k 1%
R81 100
R96 100k
Q21 2N3906 R92
1k
D15 1N4148 D18 1N4148
R65 200k 1%
D14 1N4148
R82 2k
R71 10k
U10A LM13700
111
8
7 5
4 2 3
6
D16 1N4148
R86 71k5 1%
C34 470p
R78 649k 1%
C30 220p
R90 34k0 1% 1/4W
C26 47p
R84 162k 1%
C28 100p
P3
S2A
J3
C33 220p
Q14 2N3906
Q16 2N3906
Q20 MJE340 Q24 MJE350 D21
1N4007
Q26 MPSA42
R70 100k 1% R74 200k 1% R76 402k 1% R68 402k 1% R64 60k4 1% R89 100 R95 100
R98 4k7
R79 649k 1%
Q22 2N3906 R94
1k
D17 1N4148 D19 1N4148
R66 200k 1%
R73 10k
U10B LM13700
1116
9
10 12
13 15 14
6
R87 71k5 1%
C35 470p
R80 649k 1%
C31 220p
R91 34k0 1% 1/4W
C27 47p
R85 162k 1%
C29 100p
P3
S2B
J3
Q18 MPSA92
R83 100
C25 100n
C24 100n
TP6 TP7
Q34 2N3904
R163 100k
Q39 MPSA92
C51 22p
C52 22p
Q17 MPSA92
Q38 MPSA92
GridA
Grid2 Grid1 Grid0 Grid3 Rate Hold
A/B
Gmod
IkA
GridB
Grid2 Grid1 Grid0 Grid3 Rate Hold
B/A
Gmod
Shutdown
IkB
Shutdown