This amplifier for hearing aid was found in a 1968 documentation using an integrated of the time. The power is from a battery, the consumption of 1.65 mA and the power of about to 1 mW.
With each touch on S1, an output of 4017 is activated, this in sequence 3, 2, 4, etc. These...
A touch of the X1 sensor causes the motor to be activated for a time that can be adjusted in P1....
The circuit illustrated in the figure can be used to detect earthquakes or vibrations of...