Even more power saving, alternating switch bewteen loads - Page 1
Forum section: electronics / projects

author: b_force
author_rank: Super Contributor
timestamp: August 18, 2016, 10:14:45 am
content: Just an idea/concept I would like to share.I was working on a project for a customer.In this case everything needed to fit around a very limited power supply.This was a bit of a problem, because I didn't had enough current for multiple LED indicators.Because I also needed a certain size and amount of light, I couldn't go for smaller LEDs.Luckily I was using a ucontroller and had some ports left.I came with the idea of switching the LEDs out of phase (alternating).So when one LED is one, the other one is off and vice versa.Therefore the power supply sees only the load of one LED at the time.If you do this fast enough, it still looks like the LEDs are just on.You could even do this in a chain of LEDs, but care must be taken with the switching frequency.Also it could be done with other types of loads, lamps etc etcAlthough, LEDs switch relatively fast, I don't know what will happen with a plain (old) light bulb?Anyone?

author: Zero999
author_rank: Super Contributor
timestamp: August 18, 2016, 10:22:58 am
content: I don't see why you can't just increase the series resistor to drop the LED. All you're doing is tuning the LED on and off with a duty cycle of 50%, which will make it appear to emit half as much light due to the low pass filter effect of the eye.The only time using sort high current pulses can save power is in IR remote control systems or when a light is needed to blink at a low flash rate. Otherwise, LEDs are generally more efficient when driven at lower currents.

author: Seekonk
author_rank: Super Contributor
timestamp: August 18, 2016, 10:36:41 am
content: Good idea that many just don't think about in this on demand, I want it now world. Regulator size and battery capacity can be better managed. Even PWM of relay coils. I proposed this same idea on a bigger scale to a mobile food vendor that travels to fairs. He was allowed 20A max and most of his loads were heaters and combined totaled close to double that. Those loads were now scheduled. A business started each morning with employees turning everything on all at once, they had to pay extra rate for max demand. I schedule and prioritize loads on my solar power system.

author: b_force
author_rank: Super Contributor
timestamp: August 18, 2016, 10:37:45 am
content: True, there are always multiple ways to fix a problem.In this case, lowering the resistor value was a bit impractical for other reasons.It's more about the concept of switching loads to reduce power.edit:@SeekonkThat's indeed more or less what I mean.In some case a system can't deliver the peak load when everything is turned on at ones.If you turn on everything on a alternating way, you can take care of the loads much easier.Especially handy with heaters, light bulbs etc (probably would even work for tubes, for the tubiefanatics)

author: LabSpokane
author_rank: Super Contributor
timestamp: August 18, 2016, 11:08:32 am
content: If you're really worried about power, dump the ballast resistor and use/make an LED driver.The "plain old light bulb" already switches at 50/60 Hz, just with a sinusoidal wave.