DC Small Motor Control using PWM

message: Greetings, I have a kit motor controller. I works just fine. It uses the NE556. I read some where ( on a NE555 )that I can change one of the capacitors with a variable capacitor to get the full range of frequencies out of the NE555.

 Is it possible to get adjustable frequencies out of the NE556? I have the circuit drawing. Is there any one I can send the diagram to so they could tell me which capacitor I can change? Thank you,

BR USA

PWM DC Motor Speed Control – This is a circuit for controlling the speed of small DC motors, it works nicely as a speed controller for an HO or N gauge model railroad.

Timing 555 Motor Speed – It uses a variable frequency 555 astable. The astable triggers a monostable that produces pulses of a fixed width. At lower frequencies, the monostable pulses are infrequent and the output is high about 20% of the time.

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