This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at the end of the timer, erasing the other. The timing can be increased by increasing C1.
This circuit uses a FET and a BJT to give a x300 gain for the input signal. So a 50 mV signal at...
This one-transistor alarm can be used with much more sensors than the two shown by the figure....
June 2017 - The new TE Connectivity FSJMI series of illuminated tactiles switches is now available in Mouser...