Single chip TTL touch switch circuit diagram

Here, only one integrated circuit chip T065 touch switch is used. It is small and has low power consumption, and is suitable for small current appliances such as transistor radios as contactless switches.

The figure below shows the working principle. YF3 and YF4, as well as C3 and R3, form a monostable trigger. This circuit has only one stable state. When the external trigger signal is input from the D terminal, YF3 is closed, the potential at point A rises, and the potential at point B rises accordingly, causing the output level of YF4 to rise, and its feedback line is input to the input terminal of YF3, so that the output of YF3 remains closed. However, as C3 charges, the voltage across C3 rises exponentially,