I want a bright flashing display light. Imagine the sort of thing on a one armed bandit machine, that flashes a couple of times a second. And it would run for days on end. So either one of these which are rated at 5W:-

LED bulb



but the former is preferred as it contains all the necessary current control and is very easily replaceable without soldering.

Are these suitable? I'm concerned that as they run hot they'll be no different than an incandescent, suffering continuous thermal shock and mechanically breaking. Is there a more suitable high power LED for flashing or might I just as well use a traditional filament bulb?

There's Strobing very high power LEDs but that seems to deal more with frequency than resilience. There are some other questions too but again they seem to deal with implementation issues.

  • 2
    \$\begingroup\$ Notice that LEDs are much better suited than incandescents, partly because their temperature cycle will span maybe 100C max while light bulbs go to 2000C+. \$\endgroup\$
    – JimmyB
    Jul 15, 2017 at 14:51
  • \$\begingroup\$ "flashes a couple of times a second" - In that case the temp cycle span will be negligible. The LED itself will not be your problem; as usual, the driver circuit is more susceptible. That's why I'd recommend against the first part; its driver is not designed for millions of on/off cycles. Find an LED driver (chip) with an "enable" input. If that input is specified for use for brightness control via PWM you can be certain that it will last for a lot of switching. \$\endgroup\$
    – JimmyB
    Jul 16, 2017 at 18:53
  • \$\begingroup\$ @JimmyB What would cause the driver to fail if the LED chips themselves don't? \$\endgroup\$
    – Paul Uszak
    Jul 16, 2017 at 22:15

3 Answers 3


The first one is a LED bulb, the second is a bare light emitting diode (LED). LEDs can be driven in pulses and in most applications they are.

The LED bulb may contain a semiconductor current driver or may use a single resistor. If current is limited only with a resistor you can safely drive it with pulses with constant voltage amplitude. Otherwise you should check how the internal electronics will work in such mode. In most cases this mode will be bad for the bulb's electronics and may shorten it's life.

Pulsing the bare LED with constant current amplitude is best, but you have to be sure of the current waveform trough it and how much current overshoot occurs during turn on & turn off. This requires precise selection of the current driver and the switching off technique - breaking the circuit or shortening the LED. Not any "off the shelf" driver will work good enough.

  • \$\begingroup\$ Yes, the LED bulb is fully packed with electronics. It has some sort of regulator /buck /boost circuit inside that allows it to run as brightly on 5V (230mA) as it does on 12V (90mA). \$\endgroup\$
    – Paul Uszak
    Jul 16, 2017 at 22:13
  • 1
    \$\begingroup\$ @PaulUszak I would not flash its supply without knowing in detail the internal circuitry. Any capacitor may cause trouble. Also if you inspect the internal diagram and decide that it could safely be driven with such input, you can't be sure in a year or two will the next batch comply with the one you have inspected. My suggestion is to use the bare LED of the second picture. \$\endgroup\$ Jul 17, 2017 at 8:40

The Phillips is not made to be blinked. It is rated at 50,000 switching cycles. Also it has a 0.5 second turn on delay (warm up). It is powered by 12V DC or AC.

LINK: CorePro LEDcapsuleLV 2-20W 830 G4

The second is a cheap Chinese LED.
LEDs are made to be turned on and off.

You do not want to use either of these. Use a Cree XP-3G, the most efficient LED available today. In white or blue.

Use a Microchip MIC4802 or MIC4801 CCR driver with the enable pin driven by an inexpensive ultra low power µController. Very simple driver circuit.

Microchip MIC4802 Datasheet

This combination will give you the most efficient, very flexible, low cost, and very bright blinking LED. It is easily battery powered by a Li-ion 3.6V battery such such as Panasonic NCR18650B.

  • \$\begingroup\$ It's actually mains operated so infinite power available. The Phillips bulb obviously doesn't need a driver whilst I thought of running the other off a LM317 wired in constant current mode. Plus I can't do SMT. \$\endgroup\$
    – Paul Uszak
    Oct 20, 2017 at 12:29
  • \$\begingroup\$ One LM317 per LED string? A resistor is quite often enough to maintain reasonably constant current. \$\endgroup\$
    – Transistor
    Oct 20, 2017 at 16:20
  • \$\begingroup\$ The Phillips is powered by a constant voltage source. CC is not recommended. A Microchip CCR with enable (for blinking) would do fine with any LED. \$\endgroup\$ Oct 20, 2017 at 18:01
  • \$\begingroup\$ @Transistor Please expand immediately or sooner :-) I'm actually about to start building the LM317 circuit + hand made heatsink. I thought resistors were a no no for high power LEDs due to thermal runaway... \$\endgroup\$
    – Paul Uszak
    Oct 20, 2017 at 20:38
  • \$\begingroup\$ @PaulUszak: Sorry, I may have misLED you. I didn't see any mention of LED power and they looked like small indicator lamps. I was more concerned that you would need a lot of LEDs and a CC regulator each if you want to flash them individually. One option to consider is series connecting them all on one CC source and shorting out individual LEDs with a relay contact to turn them off. You now have one big heatsink. In this case you could use a switched-mode CC PSU to reduce the heating effect. \$\endgroup\$
    – Transistor
    Oct 20, 2017 at 20:57

The first one is a packaged consumer product that is made for direct application of a fixed voltage like 12V. It has drivers and controls embedded. It is not made to flash. If you search elsewhere you can find "consumer product LEDs" made of nothing but LEDs and resistors, typically 12V or 24V, notably in automotive replacement lighting, as well as many LED strips, puck lights, etc. These are perfectly fine with being flashed, in fact, flashing them too fast for the flashing to be visible is how they are normally dimmed. **

The second one is a raw LED emitter device. It responds very well to being pulsed, modulated or flashed at any imaginable frequency, but needs a driver circuit which is correct for this application, nominally-constant-current, but in your case, modulating current.

** But this is not the best way to dim LEDs. They can be dimmed simply by regulating their current flow. In this mode, they are the most dimmable lights ever made, happy to perform from "barely perceptible" to their max rating.


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