This circuit was found in a 1980s document. The integrated circuit is from the time and the power supply must be symmetrical. Note the types of components that should be used to obtain the desired temperature compensation.
In this alarm R1 and R2 can be 10k. The SCR is any 106 Series SCR and V1 is an oscillator buzzer....
This circuit was found in an 80's General Electric documentation. The circuit uses uncommon...
The HA2620 integrated circuit used in this comparator is from the 80's, but the setting can be...