Aug 26 2010, 11:27 AM
QUOTE(pseudoblue @ Jul 1 2010, 12:36 AM)
Hey alan, the PhD-M6 is really impressive in its technical abilities, these guys are the bomb! But what I'm puzzled is about the PWM regulation for incandescent bulbs, am I missing something here? Cause I thought the pulse width modulation is bad for the filament?
QUOTE(susuman @ Jul 1 2010, 12:53 AM)
Oh, there is PWM for incans? Interesting, For some filament, the PWM will cause vibration in it, hence weaken the filament.
but Pseudoblue, its depends on the construction, the house holds incans light bulb uses PWM too, its a sine wave 60 Hz (AC power)
, maybe that is the reason its does not last?
Hi there. I am William, the designer of the PhD-M6 custom pack. I noticed the references to my PhD-M6 pack so I decided to stop by and answer/clarify some of the questions I saw.but Pseudoblue, its depends on the construction, the house holds incans light bulb uses PWM too, its a sine wave 60 Hz (AC power)
, maybe that is the reason its does not last?The PWM is not bad for the bulb's filaments, in fact, it has been used successfully for decades. The soft-start and the regulation greatly extend the life of bulbs, so the benefits are real and tangible. Willie Hunt was one of the early pioneers in using a micro-controller to create the PWM signal to regulate incandescent bulbs, and his old web site still has a lot of very good information and explanations as to how PWM works:
Lightbulb Voltage Regulators
QUOTE(alantch @ Jul 1 2010, 01:44 AM)
I'm no electronics or materials science engineer, but I don't think PWM is bad for an incand bulb, since it's just pulsing the filament at relatively high frequencies after it's lit. They're also using soft start with the circuit. The multi-level switches from AW for the M6 also makes use of PWM to drive the bulb at different levels.
That is correct. Although I don't know first hand exactly that algorithm/frequency AW uses in his soft-start, multi-level driver, his driver and the the PhD drivers (including the PhD-M6) use PWM to provide the soft-start. What the PhD drivers adds in addition to the soft-start is the voltage regulation: as the battery drains, the duty cycle of the PWM signal is adjusted to maintain a constant voltage at the bulb, to achieve a constant brightness.If I can be of further help to clarify/expand on anything else related to the PhD-M6 pack, please do let me know.
Will
QUOTE(pseudoblue @ Jul 1 2010, 03:14 AM)
What I've read so far is that the if the PWM frequency is high enough, it would keep the filament hot and constant on before it can cool down and shuts off. I guess that's okay? Still can't get a definite answer yet.
The PhD drivers use a frequency of approximately 250 Hz. This is fast enough that to the bulb, there is no ON/OFF cycles, but a constant level as the bulb's filament is averaging the PWM signal to give a constant RMS voltage.
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