PWN controllers for HO

Discussion in 'HO Scale Model Trains' started by kenken, Aug 27, 2009.

  1. kenken

    kenken New Member

    Hi all.
    I would like to make PWM controller for HO.
    My AC adapter has 16V 4.5A output.
    Does any one has electorical diagram of PWM controller?
  2. pgandw

    pgandw Active Member

    I typed "PWM throttle" into my Google search window, and came up with 3 different circuits in the 1st four listings. I typed in "DC throttle" and came up with a couple of sites with circuits for many types of transistor throttles.

    Is there a particular reason for choosing PWM over other types of throttles?

    my thoughts, your choices
  3. kenken

    kenken New Member

    Hi pgandw.
    I use this circuits now. some parts are changed for 4A output

    My aim is try someting new throttle.
    They say PWM is better for slow speed with more power.
    I would like to test it by myself.
    For first step I need simple PWM circuits.

    I searched only in Japanese,
    So I will try it again in English today.
  4. pgandw

    pgandw Active Member

    I don't know that the motor cares about how the pulses are generated. The frequency and shape of the pulse have to be controlled for best slow speed operation without overheating. Pulse width modulation (PWM) is a rather simple and efficient method of producing pulses.

    One of the problems is that a low pulse frequency is needed for super slow operation of the motor. The harmonics in the pulse land right in the audible frequency range, causing a motor to be "noisy". And the pulses need to be "fatter" and "higher" at low frequencies, causing more heating problems. Today's DCC decoders (which use PWM for motor control) have higher pulse frequencies to avoid these problems; they have good but not great slow speed capabilities. But we don't often run our models at super slow speeds, either.

    Enjoy building and testing your new throttle. Your English is much better than my Japanese. I hope what I said makes sense.

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