Star Tech Journal

S*T J
GOTTLIEB AUXILIARY lAMP DRIVER BOARD
The Auxiliary Lamp Driver
Board, introduced in the game
"Time Line", is the newest
addition to System 80 circuitry.
Its controlled or free-running
sequential lamp strobing
enhances the attract and game
play modes of Gottlieb games.
The circuit controls ten MPS-
U45 transistors (01-010) which
sequentially drive up to 30 #44
lamps (three lamps per
transistor maximum).
Strategically positioned lamps in
the lightbox or on the playfield
can create great lighting effects.
An LM555 (US), used as an
astable multivibrator, generates
a nine hertz frequency. The nine
hertz frequency is gated into a
7490 decade counter (U3)
through U1 (Pin 2), a 7400 nand
MARCH 1981
5
e 0
respective to the BCD count.
The 7405 (U2) inverts the
pulses to provide .11 second
positive going pulses
sequentially to the bases of the
driver transistors.
gate. An external control can
enable or disable the driver
circuitry at Pin 1 of U1. A logic
low on Pin 1 will turn off the
lamp strobing. If no external
signal is used, as in "Time
Line", the 3K pull-up resistor on
Pin 1 provides a logic hi to U1,
enabling the driver circuitry.
The nine hertz signal is then
applied to Pin 14 of U3, the
7490 decade counter. A BCD
count is then produced at Pins
12 (1 bit), 9 (2 bit), 8 (4 bit)
and 11 (8 bit).
The 7442 4-line to 10-line
decimal decod~r (U4) receives
the BCD count and generates a
low logic pulse at the output
B B
[J 9 8 B
c:::::::J
~
0
R1O
AIIJI
C4
U3
c2 =
c1Q
0
C
3
U4
0
~ D
Rt3
c:J
(
BUG
Rl2
) Q2
~
\
-- )Q3
~
\
}Q4
~ <
)Q6
~
<
) Q1
~
<
)Q 9
\
;,)Q10
ci \
-""i"T
)QB
COMPONENT
DIAGRAM
, 5V DC
+ liV DC
"
• 5V DC
A11J1
TO Ul ~ N 1
'
7
• 5V DC
U1 . U2 ,
r;:;N 7
ANO U6 ~
N 14
..
7
GNO
• 5VD~
,
• 5V DC
U4
SN7442N
..
• 511 DC
• 5V DC
12
FROM A11J1
PIN 1
15
10
11
R1
UJ
"
"'
SN7490N
_ _ _ ___._---'---f
!D
J
__!!L__
"
"
SN7405N
"
12,
1J
11
"'
12
"'
"' "
, 10
NOT USED
"'
10
7400N
1/~
, 11
11
10
"'
FLASHIMG LAWS
~
LOCATED IN UTEIOX
,,_r---.._,___,,
0
11
~
12
1
J
AUXILIARY LAMP DRIVER BOARD
SCHEMATIC
. . .
. . .
. . .
AI IJ 2
)Q5
ci ~--
RII
0
)Q1
6 <
U1
Reprinted courtesy of Gottlieb's "On Target" Technical NewSletter
0