This circuit is from a 1969 Electronics World. The transistors may be modern general-purpose equivalents. The circuit is for frequency ranges between 250 Hz and 250 kHz.
Written in an article in Radio Electronics magazine in April 1987, this circuit triggers an alarm...
This is the receiver circuit for the previous transmitter. The circuit has a programming key to...
This is an example of a temperature sensor shield using the Texas Instruments TMP390 obtained from...