Global Specialties PB-502 - Manual - Manual (Page 12)

12
OPERATING PRECAUTIONS
The Logic Indicators and Seven-Segment Displays are intended for use only with digital
signal inputs having voltage levels of Vcc or ground. It is, therefore, recommended that
all interfacing be done with digital circuitry operating from the Vcc tie points. Exceeding
Vcc, (12 volts with the CMOS/TTL selector jumpered to the CMOS position, 5 volts with
the jumper in the TTL position) at any input will cause circuit damage to the PB-502 as
will input voltages below ground. If necessary, input protection can be constructed on
the UBS-100 solderless breadboarding socket. This circuit should protect any input over
the voltage range of -15 to +20 volts without affecting input thresholds