12
globalspecialties.com
Global Specialties
The PB-503A 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.
Components and Features
Debounced Pushbuttons (Pulsers)
Potentiometers
Two potentiometers are provided on the trainer. The resistance values chosen (1 kΩ and 10
kΩ) 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-503A 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-503A 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 V (ground) for a logic low, and logic high
levels of 5 V or +1.3 to +15 V at the voltage setting of the +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.
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.
(Continuation)
CAUTION
