Author Topic: Philips 538249 4W Led "Party" Bulb  (Read 431 times)
John
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Philips 538249 4W Led "Party" Bulb « on: December 03, 2023, 04:30:04 AM » Author: John
Hello folks, odd question but I'm wondering if this lamp would be suitable for chasing / flashing? I know that the LED itself wouldn't mind but I'm not sure about the driver?

Just to be clear I'm refering to switching the lamp on & off in the 1Hz - 2Hz range, not dimming it. I know dimming is not acceptable according to the spec sheet.
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Medved
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Re: Philips 538249 4W Led "Party" Bulb « Reply #1 on: December 03, 2023, 05:17:33 AM » Author: Medved
The formal rating is 15k hour and 20k cycles, so hard to say (the "cycles" cycle is something like 15 minutes ON, so stoll not much comparable with your pattern).

Because they are of the filament in glass envelope, the ballast is most likely a rectifier ana a constant current source. Question is, whether there is also a smoothing capacitor or not, as the inrush current into that capacitor would be the thing killing it with frequent switching.
It is designated as a "party" lamp, so that would suggest it wouold be designed for frequent switching and the 120Hz flicker to not be a problem, so suffice without that filtering tank capacitor, but the published power factor figure is just 0.4 and a rather low switching cycle rating (20k cycles with 15 min/cycle test pattern by far won't make the rated life of 15khours, so there is something degrading with switching), which would suggest its presence.

But regardless, there is a way to reduce the inrush stress: Connect a resistor in series (so it will dissipate about 0.5..1W or so, so about 150 Ohm for each lamp), but the question is, whether your installation will allow it (if you are just designing a chaser sequencer yourself, you may add that easily, but just wiring ready made modules won't allow that).
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