Found in a 90's EDN, this circuit controls both the speed and the direction of rotation of a stepper motor. Relays can be replaced by MOSFETs, with circuit adaptations.
The frequency of this circuit depends on the crystal. The transistor supports a modern equivalent. We...
Indicated in Maxim's documentation from the 90's, this circuit has a gain of 40 dB and an output...
The time obtained in this circuit, from a 1978 publication, depends on R3 and C. R3 can have...