For newer Telescript Tally One units (Red/Amber/Green), and if your tally system outputs a
“Standby” or “Ready” signal, the following technical information explains the interface.
The sensor input is a standard 3.5mm stereo phone jack. The sleeve is grounded and the tip
and ring are each pulled up to +5 volts by resistors. The voltages at the command inputs are
compared with the setting of the threshold potentiometer located on the side of the tally. This
can be set anywhere between approximately 0.7 and 4.3 volts. Command signals can be sim-
ple contact closures to ground, or a variable resistance such as a light dependent resistor, or a
logic signal. If logic signals are used, a swing of at least 2V is recommended. The tally can tol-
erate swings as high as +/- 12V.
The command inputs are active low, therefore an open circuit or high logic level is ignored.
The tally responds to the four possible command combinations as follows:
TIP = H, RING = H displays green
TIP = H, RING = L displays amber
TIP = L, RING = H displays red
TIP = L, RING = L displays red
Each tally has an associated 3.5mm output jack labeled “REPEAT”. When the display is green,
the output lines are open circuit. When the display is amber or red, the associated line offers a
low impedance path to ground. The repeat output can be used to daisy chain devices for con-
trol from a single input. Note that devices which do not support amber do not repeat the am-
ber signal. In such instances, the tally should be the first device in the daisy chain.
SLEEVE
100K
100K
RING
TIP
RED COMMAND
1
2
3
+5V
AMBER COMMAND
