Abstract: A bar graph device has a column of 200 cathodes connected in three sets which are energized in sequence to give a visible gas discharge which travels up the column from a reset cathode. The cathode drive is from a clock which also drives a sawtooth which is compared with the input signal. When equality occurs, the anode is de-energized to extinguish the discharge. Cathode drive continues until all cathodes in the column have been energized. Divide-by-200 circuitry ensures proper resetting. Scale markers are provided in the display itself by splitting the divide-by-200 circuit as shown, and using the pulses from the divide-by-5 section to fire a one-shot and a disable gate for, say, three clock pulses. This effectively freezes the system after every five pulses passing through the gate, resulting in the display in the device dwelling on every fifth cathode; these cathodes, therefore, appearing brighter than the rest.

Abstract: A dual limiter circuit for limiting an input signal between high and low limits and having a first and a second operational amplifier with the positive inputs of the amplifiers being supplied with respective threshold, or limit, signals. A third operational amplifier has its positive input supplied with an input signal to the limiter circuit. A respective output impedance for each amplifier connects the output of the corresponding amplifier to the output of the limiter circuit while a feedback connection from the limiter output circuit is connected to the negative inputs of all three amplifiers. This dual limiter circuit operates for all values of the input signal to have one of the amplifiers operating in its linear region to control the output signal from the limiter circuit while the other two amplifiers are operated in saturated states in opposite senses.