Transformer less Power Supply.

Discussion in 'Feedback and Suggestions' started by BR-549, Jul 28, 2015.

  1. BR-549

    Thread Starter Well-Known Member

    Sep 22, 2013
    1,987
    388
    I think it's time to end the transformer less power supply ban.

    I think the liability issue is false.

    Multi phase motor controllers with a + 800 VDC bus, without isolation maybe discussed, but not a 120 V r-c or solid state circuit.

    With the processor chips and wifi chips, everything will be IOT and networked.

    I think this will happen quickly, and that AAC is already behind.

    Many manufacturers are showing several methods for power, directly from 120 V and 220 V lines.

    Many methods are UL approved.......I would think, because many methods are in use now.

    I think in a short time, these IOT devices will be pasted everywhere. Without transformers.

    Isolation transformers are great, I've always used them. But they are too costly, bulky and heavy for many more commercial products. Everything is small and lite, yet versatile and connected.

    AAC should man up, and be a leader in this new application.

    Hobbyist and experimenters will try to apply this whether AAC allows it or not.

    I think it is a dereliction to the purpose and spirit of AAC, not to address the safe, proper design and application of these circuits.

    The new AAC site has a whole section on IOT. How long or where do we go, to learn how to power it.

    If AAC owners are unconvinced, have your marketers go to the other sites, and check the interest in transformer less power supplies.

    BR-549
     
    MaxHeadRoom likes this.
  2. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    You are entitled to your opinion. I disagree, but it is not up to me either.

    This is not a liability issue, it is an issue about people getting hurt, same as rail guns and many high voltage projects. Just because you can do something does not mean you should do something.

    Just because other site do it do not pertain. Go to the other sites if it is that important to you. It still is not safe, and can not be made so for hobbiest use.

    I know of no reputable design that does this, care to name some examples? As in science, saying it is so does not make it so. I just disassembled a USB power cube out of curiosity, it too has a transformer for all it's small size.

    This is not saying we do no allow AC power in projects. Indeed, many projects use transformerless power supplies internally, then isolate the connection to the user later. It is the risk of someone finding a live voltage, either through failure or bad workmanship, that is the kicker. We are not talking commercial projects. UL codes do not apply here.

    Saving $3 in parts is not worth the dangers it presents, and I will fight this particular subject while it is open.

    Just curious, what have you build using discrete components before? It goes to a skill level that affects judgement. I have hundreds of projects build from the ground up under my belt. I do not consider building a computer using store bought components in this catagory.
     
    Last edited: Jul 28, 2015
    absf likes this.
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Newbies, with maybe one or two Battery-powered 555 and LED projects under their belt, cannot be trusted with transformerless, line-powered projects. Folks experienced enough to do it, do not need to ask for advice here...

    I can buy all the transformers (wall warts and bigger ones) I need for small projects at my local thrift store for between $0.25 to $4.00.
     
    OBW0549, boatsman, JohnInTX and 2 others like this.
  4. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    Safety should be the overriding concern. I think the "Transformer-less power supply ban" should be changed to the "Dangerous Circuit Ban". ANY design, through normal use, that is dangerous or has a reckless disregard for safety, should not be allowed on the forum. There are cases, where the circuit is inherently dangerous during development, but is rendered harmless in its final form. These cases can be resolved simply by asking a question in this section. I recently did it by asking if it was OK to post a power factor correction circuit that I was having trouble with. (It connected directly to the mains but the isolation was achieved in the following power converter.) The Mods considered it, asked questions, and finally gave me the OK. (I have yet to post the PFC circuit.)
     
  5. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    The old 5 tube radios were, "straight off the line" and some early TV's, but they are now considered prime examples of bad engineering.
     
  6. BR-549

    Thread Starter Well-Known Member

    Sep 22, 2013
    1,987
    388
    Diverting the post to my credentials will not change reality.

    Please refrain from personal attacks.

    Google transformerless power supply.

    Many examples of what I stated.

    From several areas of industry.
     
  7. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Read what I wrote, not what you want to hear. This is a hobbyest site, not an industry. Beginners make enough mistakes on their own without encouragement. The fact you are pushing for this does speak to your qualifications. If you are not qualified to build a power supply from scratch, how can you properly advise someone else how to do it safely?
     
  8. BR-549

    Thread Starter Well-Known Member

    Sep 22, 2013
    1,987
    388
    So if someone disagrees with you, they lose or degrade their qualifications?

    I was under the impression that the only qualification needed was to be a member of AAC.

    I was also under the impression that the new owners welcomed feedback and suggestions to improve the site and increase membership.

    This is my contribution to that goal.

    Is that ok with you, Wendy?
     
  9. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    What qualifications? You have not stated any concerning DIY electronics, or building a power supply from the ground up. I have build many, made some smoke too. Experience counts.

    Again, it is not my decision. This site is owned. I do, however, have very strong views on the subject based on experience, and do not hesitate to express them. Transformerless power supplies are not safe by design.
     
    cmartinez likes this.
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,800
    1,103
    Mike's first sentence in post #3 sums it up nicely.
     
    JohnInTX likes this.
  11. BR-549

    Thread Starter Well-Known Member

    Sep 22, 2013
    1,987
    388
    After participating in a recent post, I do declare that I am totally wrong about this.

    People are just too ignorant.

    As I have been. I regret this and apologize to all.

    BR-549
     
  12. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    Welcome to being Human. I am constantly amazed at the level of stupid that surrounds me. About 10% of my career was about fixing things that 90% of average persons could do it they would only bother to look at the thing that is malfunctioning.

    "My TV is dead."
    "There, I plugged it in to the wall outlet."

    "My garbage disposer won't drain."
    "There, I jerked the pulverized broccoli loose with a toilet plunger."

    "A board fell off my wooden fence."
    "There, I put a couple of nails in it."

    "Winter is approaching and I want you to start the pilot light in my furnace."
    "I was there last year. You don't have a pilot light. Turn the thermostat on."

    "I want to plug a cord into the wall outlet and stick my fingers in the circuit. Which wire will hurt me?"
    "Not on this website!"
     
    boatsman likes this.
  13. wayneh

    Expert

    Sep 9, 2010
    12,123
    3,047
    I'm not keen on the quaint idea of protecting people from themselves by withholding information. You can't fix stupid. I doubt it does any good and may do harm by driving them to other less savory sites. I looked up the definition of "sanctimonious", and it fits like a glove. Just my two cents. I'm not asking for a change.

    I support the ban on overtly dangerous topics that might harm others beyond the user, railguns, lasers, bombs and such.
     
  14. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Which also describes the transfomerless power supplies. The user will be showing off his project, possibly even loaning it to people.
     
  15. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    Yep. You never know when some beginner will put a beginner level project in a small box and take it into a Texas school to show off to his science teacher (and several other people).:D
     
    boatsman and cmartinez like this.
  16. cmartinez

    AAC Fanatic!

    Jan 17, 2007
    3,573
    2,537
    Sad to admit, but stupidity can and does reproduce
     
    boatsman likes this.
  17. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    ps, love your present avatar. You have discovered the cause of the 1960's.:D
     
    cmartinez likes this.
  18. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,545
    2,370
    Off the shelf DC powered items presently ran directly off of 240/120 AC and often openly discussed here.

    All Treadmill electronics.
    KB DC motor drives.
    On line TRIAC/SCR control circuits
    Advance Motion Servo Controllers.
    Copley controls Servo drives.
    Aerotech Motor controls.
    Washing machine Outrunner motor controllers.
    ECM HVAC motors.
    All VFD's
    etc. etc.
    Max.;)
     
    Last edited: Jan 5, 2016
  19. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    @MaxHeadRoom

    And yet not one of those designs offers the user access to the voltages. They are also commercial designs and not DIY.

    Please keep it real and on subject. That was borderline offensive. I do not enjoy these endless debates of me doing my job here. I did not make this rule, though I support it completely.

    You do not like these rules take it elsewhere. Please.
     
    JohnInTX likes this.
  20. JohnInTX

    Moderator

    Jun 26, 2012
    2,345
    1,028
    Here are links to a couple of posts I made on the subject, not because I think they are any better than others' comments but mainly because I remembered where they were.. The rest of the threads can be scanned for context.
    http://forum.allaboutcircuits.com/t...is-restricted-here-in-aac.118877/#post-940935
    http://forum.allaboutcircuits.com/threads/mains-circuits.118118/#post-929852

    I don't think the IOT (or anything else) using transformer less supplies argument holds water. Nor does posting a list of AC powered devices. Things plug in. I get it.

    This is an educational site. There is nothing about IOT, or most other subjects here, that can't be taught, prototyped or even constructed as a project that can't be done with a battery, wall-wart or power transformer. If you are in a position that requires transformer-less power to cost-compete in a production environment and sell stuff in blister packs you are in the wrong place. Those things happen in engineering labs with careful attention paid to safety standards (UL, CSA, CE etc.) and as I noted in the linked posts, if you have to ask how to do it, you are not qualified to mess with it.

    I have designed lots of line-direct stuff. But on the bench, in prototype and even when debugging/testing/servicing production units, they are always powered through an isolation transformer. Again, if you have to ask why, you shouldn't be messing with it and the matter of expectation noted in the linked threads always applies - IMHO.

    This subject has been noted and seriously reviewed by the mods and owners of AAC. I am not in disagreement with the merits of a transformer-less supply when applicable but this just is not the right place. As noted above, you can't fix stupid - but we don't have to kill them either.
     
    Last edited: Jan 5, 2016
    cmartinez likes this.
Loading...