Do Special Effects Slow/Fast Flashing/Blinking LED use less power than reg LEDS? - Page 1
Forum section: electronics / beginners

author: Altair8800
author_rank: Regular Contributor
timestamp: January 13, 2023, 11:44:29 am
content: You can purchase 2-lead (prong) LEDs that have a special effect of Slow (~1-1.5Hz) and Fast (~2-6.8Hz) Blinking/Flashing.The question I have is do these premade blinking/flashing LEDs use less power than a standard LED (of same color) and about how much less power do they use?Thanks,I know that pulsing (PWM) an LED you can reduce the LED power (sacrificing some brightness), and assume that these SFX blinking LEDs work this way but not 100% certain. I couldn't easily find this answer online (and I do not yet own an oscilloscope)...

author: Ian.M
author_rank: Super Contributor
timestamp: January 13, 2023, 12:00:48 pm
content: Why would you think they use less power vs an ordinary LED of the same colour and semiconductor material, with comparable LED die area being flashed at the same intensity, rate and duty cycle by an external driver designed with efficiency in mind?Hint: There is no room in an ordinary leaded LED package for inductors or capacitors of significant value, so the controller die must have a linear regulator to stabilise the LED current against variations in supply voltage. Linear regulators are notoriously inefficient . . .

author: wizard69
author_rank: Super Contributor
timestamp: January 13, 2023, 01:56:58 pm
content: Quote from: Altair8800 on January 13, 2023, 11:44:29 amThe questions is should you.QuoteThe only way to answer this is to review the data sheet. Assuming these are well documented parts, it should be easy to determine over all power draw.QuoteYou will have to look harder for an online data sheet.

author: Ian.M
author_rank: Super Contributor
timestamp: January 13, 2023, 02:10:33 pm
content: Quote from: wizard69 on January 13, 2023, 01:56:58 pmGood luck with that! Here's the seller's page for the above LED:https://www.budgetronics.eu/en/leds/leds-blinking/flashing-led-yellow-5mm/a-353-10000036There's no manufacturer, part number or datasheet to be found, so its either measure a statistically significant sample or find a different flashing LED at another supplier with better traceability to the manufacturer.

author: CaptDon
author_rank: Super Contributor
timestamp: January 13, 2023, 02:12:51 pm
content: Considering they run at about 20ma. when on and .5ma. when off with a 50% duty cycle the average draw would be perhaps 10.5ma. I should think any external circuit you could rig up to flash a normal led wouldn't use any less power. Not sure about the power consumption of the CMOS version of a 555? You are trying to reduce the steady .5ma. draw of the active electronics. The power to produce equal brightness on the LED die won't change when speaking of the 'on' time. 20ma. being about normal for many plain jane LED's.

author: Ian.M
author_rank: Super Contributor
timestamp: January 13, 2023, 02:23:32 pm
content: The problem is the voltage drop across the linear current regulator that flashing LEDs invariably contain. Its only got to be 30% of the LED die Vf for you to be able to do far better with an external driver, even if its only the LED and a choke in series, with a free-wheeling diode across the pair, with a low side MOSFET PWMed by a low power, low pin count MCU with a duty cycle calculated from the supply voltage for the desired average current without saturating the choke.