The AP7500 and AP7501 are useful in totalizing applications, where the total number of pulses counted in a given time period represents the time integral of the DC input. If, for example, the input represents a flow in gallons per hour, then the time integral of this flow signal (total count) will represent total gallons (see Figure 1). The AP7500’s 6V square wave output can be used to drive electronic counters (DTL, TTL, CMOS). The AP7501 can be used to drive electromechanical counters when connected to an external AC or DC power source. In the AP7501, the DPDT relay contacts are pulsed (closed) for only a short duration (100 milliseconds) for compatibility with standard electromechanical counters. The AP7500 can also be used in telemetry systems, where the dc signal is converted to a frequency, transmitted over long lines, and then decoded at the receiving end by means of a frequency to DC converter, such as the AP7380.

Application

The AP7500 and AP7501 are useful in totalizing applications, where the total number of pulses counted in a given time period represents the time integral of the DC input. If, for example, the input represents a flow in gallons per hour, then the time integral of this flow signal (total count) will represent total gallons. The AP7500’s 6V square wave output can be used to drive electronic

counters (DTL, TTL, CMOS). The AP7501 can be used to drive electromechanical counters when connected to an external AC or DC power source. In the AP7501, the DPDT relay contacts are pulsed (closed) for only a short duration (100 milliseconds) for compatibility with standard electromechanical counters. The AP7500 can also be used in telemetry systems, where the dc signal

is converted to a frequency, transmitted over long lines, and then decoded at the receiving end by means of a frequency to DC converter, such as the AP7380. 

Output Ranges

The output frequency range is selectable via the 16-position rotary switch accessible through the top cover. See tables 1 and 2 for output selection. Since ranging is accomplished through digital circuitry, the accuracy of the unit is unaffected by the switch

Specifications

Input Impedance:

• Voltage Input: Greater than 100KW

• Current Input: Less than 500mV shunt @ full scale (e.g. 20W for 20mA)

• Input Protection: Withstands 200% of span

Linearity (Best Straight Line & Linear Input):

0.25% of span, typical

Low Input Cutout:

Adjustable, 0-10% of span (factory set at 1%), LED cutout indication

Output:

• AP7500: Square-wave, 0/6V, 1:1 mark/space ratio, source 10mA, sink 50mA. Option C 50mA sink, 30V.

• AP7501: Isolated DPDT relay contacts, rated 120VAC @5A or 28VDC @ 5A (100mSec min. on time).

• Contact Material: Silver Cadmium Oxide

• Life: 105 operations at rated load

Response Time:

100 milliseconds typical, 200 milliseconds max