Abstract: To provide a printout corresponding to the integral of the current or voltage from any of several different instruments, a printing integrator includes a voltage-to-frequency converter which receives current or voltage through a replaceable buffer amplifier and provides pulses to a counter at a rate proportional to the amplitude of the input current or voltage. The output of the counter is printed in rows along with the time of printing and an indication of the state of the battery.To generate pulses at a rate proportional to an input signal, a charge is periodically supplied to a feedback capacitor of an operational amplifier from a storage capacitor in the voltage-to-frequency converter, and an input current derived from the signal decreases the charge in the feedback capacitor until the output potential of the operational amplifier drops below a level set on a comparator, thus generating a pulse and initiating another discharge from the storage capacitor into the feedback capacitor.