| 摘要 |
An electronic reostat circuit having a pulse width modulated output for controlling energization of a device such as a vehicle dashboard illumination lamp. A comparator circuit compares a reference signal adjusted by a user with an alternating signal, preferably a saw tooth waveform, and generates a pulse width modulated output whose duty cycle varies directly with the size of the reference signal. The reference signal is generated by a tapped resistor array wherein contacts on the array are coupled to ground by a rotary switch contact which can be adjusted by the user. By raising and lowering the reference signal, the duty cycle can be changed from a minimum to maximum and thereby produce a minimum and maximum lamp illumination signal.
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