time switch - or NiCd chargers

elektor december 1984 The usual inexpensive NiCd chargers available in electronics retail P9 outlets are normally of Far Eastern origin, but that in itself is of littie consequence. They often suffer the disadvantage, however, of not having a charging time control. You therefore have to keep an eye on the charging times and this may be done with an ordinary alarm clock. This is not the answer, however, if you want the charging to be done while you"re away. In that case, you could not do much better than build the inexpensive time switch described here: it is so small that it can readily be fitted inside the housing of most chargers. timé switch .. . ...for NiCd chargers The circuit diagram of a popular inex- pensive NiCd charger is shown in figure 1. Here, the NiCd batteries are charged from half-wave rectified and transformed-down mains voltage. Four 1.5 V cells and one 9 V battery may be charged simul- taneously: two of the four 1.5 V cells on the positive half cycle and the o...