TO CHARGE OR CHANGE?

The device was created to check the capacity of Nickel-cadmium and Nickel-metal hydride batteries, but they can check for any small capacity batteries and dry cells. The device is composed of two parts — digital multimeter and active load. The voltmeter consists of a transmitter “amplitude-time” on the element DD1.1 and the transistors VT1 — VT4, generator counting pulses on DD1.2 and pulse counters for DD2 — DD4.

 

Generator DD1.1 (assembled in the Schmitt trigger) generates a sequence of short positive pulses with a repetition period of about 0.5 s, and, opening the keys on the transistors VT1 and VT2, charge capacitor C4 from the source of the measured voltage. During the charge, you also reset the counters at the input R to prepare for the cycle count. After charging starts discharge C4 through the current generator to VTЗ (linearizer level) and the transistor VT4, which in turn, through the logic elements DD1.4 and DD1.3 to permit the passage of the counting pulses from generator DD1.2 (assembled as DD1.1, also in the Schmitt trigger) on the counters DD2 — DD4. Thus, the counting of pulses occurs during the discharge of the integrating capacitor C4. The discharge time is proportional to the amplitude of the measured voltage. The rest period after the reference (category C4) to the leading edge of the next pulse falls on the indication.