Global Specialties PB-503 - Manual - Manual (Page 11)

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selected. The 100KΩ input impedance ensures minimal loading effects of the circuit
under test.
DEBOUNCED PUSHBUTTONS (PULSERS)
The PB-503 uses clocked flip-flops to provide debounced pushbutton switch functions.
The pushbutton circuitry has open-collector outputs which can sink up to 250 mA each.
This type of debouncing gives the user a sharp, glitch-free trigger source which assures
reliable operation in digital circuits. Each pushbutton has a normally-open and a
normally-closed output. If necessary, a pull-up resistor can connect any pulser output to
any of the positive voltage sources.
POTENTIOMETERS
Two potentiometers are provided on the PB-503. The resistance value
s chosen (1KΩ
and 10KΩ) may be used in common circuit applications such as volume controls, DC
offset controls for op amps, and timing circuit controls. All leads for both potentiometers
are available and uncommitted.
BNC CONNECTORS
The PB-503 may be connected to other pieces of equipment via two BNC connectors.
This allows the use of shielded cable to minimize noise and interference.
SWITCHES
Two single pole, double throw (SPDT) switches are provided for general switching
functions. All leads are available and clearly marked on the PB-503 for easy
connection. Eight switches are configured as Logic Switches to provide a convenient
source of digital outputs. These switches will provide logic levels of zero volts (ground)
for a logic low, and logic high levels of either +5 volts or the voltage setting of the 1.3 -
15 volt +V supply. The high level is determined by the setting of the +5/+V switch. This
arrangement makes connecting special digital circuitry such as an eight-bit input port
quick and easy, and allows compatibility with virtually any logic family.
CAUTION
Integrated circuits can be destroyed if a voltage is applied to their inputs
that is higher than the operating voltage of the ICs. Always insure that the
setting of the +5/+V high-level switch is in the correct position before
making connections to any device.