This circuit comes from an English publication of 1976, consisting of an experimental touch key. The circuit uses transistors that are not common in our days, but can be replaced by equivalent. Thus, we have for the BC108 the BC548. For the BC178 we have the BC558 and the 2N2926 the reader can experience the 2N2222 or other switching transistor. Power supply is made with 9 V and can be used as load or lamp relay 9 V The maximum output current is 100 mA.
