Tachogenerator help control system?
How would the Schematics for a simple speed controled D/C motor look like by using a tachometer.? I have a rough idea but ament quite sure of the control system which gives the negative feedback and how it would transfere to the motor – diference setup shoudl be used for the op.amp to cut down on lag.
PWM can be used but would rather there was an easier way
You have the basic idea – a simple differencing controller that compares your speed setting to the tachometer feedback.
The tach signal can come from a pulse sensor on the motor shaft and be converted from frequency to voltage for the comparison loop. If the motor always spins the same direction this works fine; if it’s reversible then you’ll need to encode direction too (use a quadrature encoder for this.)
The control signal can come from a DAC, potentiometer or other DC source.
As far as the loop details, the best-known type of motor control is called PID (proportional integrator-differentiator.) Link below explains this in detail, other links in the same page have supplemental info. The wiki page (second link) has lots of useful info and external links .
The drive style is up to you. PWM is more efficient (it’s popular with fan speed controls for example) but for a small, lightly loaded motor a linear signal is adequate.
Arduino Microcontroller H Bridge PWM Serial LCD Schematic and Sketch