What tacho meter are you using.... how do you measure the speed of a dc motor and finding position of a dc motor is not possible......
---------- Post added at 16:27 ---------- Previous post was at 16:12 ----------
It has to be a closed loop to control speed or use a PID for that purpose and measure the speed using a tachometer
---------- Post added at 16:30 ---------- Previous post was at 16:27 ----------
**broken link removed**
i also think you need pwm to vary or control the speed with out which how will you control the speed without controlling PWM