This circuit triggers a relay when the set temperature is reached. The circuit is from an old documentation. The relay may be equivalent according to the transformer secondary voltage.
This circuit produces the sound of percussion such as blocks, drum, bell, etc. The frequency...
We found this oscillator in a publication from the 1960s. The frequency is around 600 Hz with the...
Found in a Popular Electronics from 1992, this circuit uses a PLL567 in an audio meter bridge that...