EEVblog #1191 - Digital Energy Savers BUSTED! - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: March 18, 2019, 11:10:53 pm
content: Digital energy saver boxes that claim to reduce your power bill by up to 50%, are...SPOILER ALERT:Complete bullshit.

author: johnlsenchak
author_rank: Frequent Contributor
timestamp: March 18, 2019, 11:49:47 pm
content: Great Scott ! The outer box should say " This power saver has a magic 'Wu Wu Flux Capacitor' that saves you 1.2.1 jig-a-watts on your real power bill"PURE 100 PERCENT WANKERY !

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 19, 2019, 12:06:29 am
content: Moving aside from the plug in energy savers that don't work, I can think of ways (other than turning things off) to make a plug in energy saver that does work, with the caveat that it only works for certain kinds of loads:* Rectifier (voltage doubled for 120V version) for PFC switching power supplies, to reduce input stage losses at the expense of lower power factor. Works even better as a modification built into the PSU in order to eliminate two diode losses.* Buck transformer for devices that use linear power supplies, most notably older audio equipment and some LED bulbs.* VFD for motor loads, would need to be part of a control loop.

author: HalFET
author_rank: Frequent Contributor
timestamp: March 19, 2019, 01:47:42 am
content: Quote from: NiHaoMike on March 19, 2019, 12:06:29 amYou can sort of out-perform many of the older power adaptors for low voltage DC I suppose. I remember a couple of years ago that some large company (think it was either Siemens or Schneider) was trying to push a 24V or 48V DC home/office system with a single large power supply and special outlets. They claimed it was more efficient, but given the performance of more recent AC-DC converters I think that's no longer viable.

author: Barny
author_rank: Frequent Contributor
timestamp: March 19, 2019, 05:28:30 am
content: Dave mentioned switching between capacitive and inductive load.Wouldn't the inductive load have to be placed in series to the capscitive load?That means that the coil need to be placed inside the distribution board.The showen device has some good sides too.The housing and powercoard are looking usefull.And the mains voltage meter seems usefull when a generator or something has to be monitored.

author: Cnoob
author_rank: Regular Contributor
timestamp: March 19, 2019, 07:11:33 am
content: I checked quite a few listings on ebay, only 8 of these energy savers have been sold.Presumably we've seen what happen to one on the video.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 19, 2019, 11:19:21 am
content: Besides the poor insulation and missing ground, there is another electrical hazard: I see no proper bleeding resistor. So when unplugging from the mains at the "wrong" moment the 3 µF capacitor can be still charged to up to some 320 V.It's at least a thing to remember touching such a cap.AFAIK the safe limit for caps without extra bleeding circuit is come 0.5 µF.At the capacitor I don't see a class X marking - so it's missing the usual mark for caps across the mains. So there may be an extra fire hazard with this cap, when it blows.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 19, 2019, 10:42:10 pm
content: Quote from: Kleinstein on March 19, 2019, 11:19:21 amThe voltmeter would probably discharge the cap, if it uses a voltage divider like most digital voltmeters do.

author: amyk
author_rank: Super Contributor
timestamp: March 20, 2019, 01:27:58 am
content: Quote from: Barny on March 19, 2019, 05:28:30 amNo, they are connected in parallel:https://en.wikipedia.org/wiki/Synchronous_condenser

author: jonovid
author_rank: Super Contributor
timestamp: March 20, 2019, 10:44:00 pm
content: its just mains voltage meter. the error is in the label

author: Deodand2014
author_rank: Regular Contributor
timestamp: March 20, 2019, 11:45:26 pm
content: I did notice there was a space for a missing resistor on the board, perhaps the manufacturer decided it was cheaper to leave it out. It's not as if the average purchaser is going to open the 'magic box'.