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Thread: Protectionism must be brought in to UK engineering

  1. #31
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    Quote Originally Posted by grumzed View Post
    Hmm, yes. There are always complaints about "health and safety" being OTT, especially when it makes items harder to install. If it's done well, there should be no complaints really and it should not make things more difficult. I think if you have worked in A&E you get another perspective. A problem is that manufacturers sometimes "game" the rules to make items cheaper. It does seem that sometimes installation experts are not consulted before changes are made!
    Off the top of my head the last one was the earth bond,regs introduced stated it had to be continuous and without breaks and bonded as close as possible to the incoming electrical supply to the meter and bonded as close as possible to the incoming supply on the gas meter.
    That's fine and pipes were always bonded before but not that close to the incoming,anyway so the story goes lightning hit a row of houses in Yorkshire melted the gas pipes and the whole row went up.
    Since 1945 how often was the legitimacy of a general election result questioned and how many received 52% of the vote?

  2. #32
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    Quote Originally Posted by Baron von Lotsov View Post
    I don't think it is usual to fail within days. I've tried some Chinese LED lights and regarding failure, a couple of bulbs exploded, but I found out it was because the lampshade prevented as much ventilation and the electrolytic caps dried out and went bang. The ones in the larger lampshades have never failed. What I have found though is they nearly always use Epistar LEDs, and they are Taiwanese. You get different bins of them, from good performing ones to cheap ones. I think the Chinese tend to use lower efficiency LEDs, plus as they are used for a few thousand hours the efficiency drops off with an LED. The bad ones have a faster rate of decline + heat reduces efficiency. This means in practice they don't give any more light out than a sodium lamp. The new ceramic metal halide lamps might even beat them.
    I had some fail within days (quite expensive ones) so I took them apart and simulated the circuitry. The first thing I found was that they used more power than specified but the real problem was that the LED chips simply got too hot. Even if the devices had been in spec. they could not have withstood the working temperature. These particular ones, even in free air resulted in the LED chips operated way over any likely spec. limit which I would reckon should be about 85C. max. It would kill them right away of course, but the life goes down rapidly. I also expect that the chips were being overpowered too but I could not check on that without seeing the chip specs.

    The problem with even well made LED lamps is that it not explained to the public that they really need free air cooling. A filament bulb's main failure mechanism is the filament which runs at about 3000C so if the ambient temperature goes up by even 100C it makes little difference to the life. For an LED, or most semiconductor devices, the max operating temperature is about 85C, or if specially designed, 125C (MIL Spec is usually this). The LED's themselves are the main source of heat (though not the only source) and may be OK in open air (though not these particular bulbs) at 25C. But if the ambient temperature around the bulb goes up by 30 or 40C they are then operating over their spec. limit and death occurs fairly swiftly, usually due to a case of electromigration. Other forms of death are also possible. RIP bulb!

  3. #33
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    Quote Originally Posted by grumzed View Post
    I had some fail within days (quite expensive ones) so I took them apart and simulated the circuitry. The first thing I found was that they used more power than specified but the real problem was that the LED chips simply got too hot. Even if the devices had been in spec. they could not have withstood the working temperature. These particular ones, even in free air resulted in the LED chips operated way over any likely spec. limit which I would reckon should be about 85C. max. It would kill them right away of course, but the life goes down rapidly. I also expect that the chips were being overpowered too but I could not check on that without seeing the chip specs.

    The problem with even well made LED lamps is that it not explained to the public that they really need free air cooling. A filament bulb's main failure mechanism is the filament which runs at about 3000C so if the ambient temperature goes up by even 100C it makes little difference to the life. For an LED, or most semiconductor devices, the max operating temperature is about 85C, or if specially designed, 125C (MIL Spec is usually this). The LED's themselves are the main source of heat (though not the only source) and may be OK in open air (though not these particular bulbs) at 25C. But if the ambient temperature around the bulb goes up by 30 or 40C they are then operating over their spec. limit and death occurs fairly swiftly, usually due to a case of electromigration. Other forms of death are also possible. RIP bulb!
    They use a buck converter chip. Efficiency of the chip depends on the frequency of operation. The Chinese chip I checked out was 70khz, which I think gives you about 90% efficiency. The better Western chips out work at 1mHz, so they give you about 96-97% I think I recall. So the solution is to use faster chips, and certainly not do what I noticed they did. A large electrolytic was glue-gunned to the chip! Well presumably that was the heatsink, but real cowboy stuff.
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  4. #34
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    Quote Originally Posted by Baron von Lotsov View Post
    They use a buck converter chip. Efficiency of the chip depends on the frequency of operation. The Chinese chip I checked out was 70khz, which I think gives you about 90% efficiency. The better Western chips out work at 1mHz, so they give you about 96-97% I think I recall. So the solution is to use faster chips, and certainly not do what I noticed they did. A large electrolytic was glue-gunned to the chip! Well presumably that was the heatsink, but real cowboy stuff.
    The type that use a buck converter are more rare and a bit more expensive. The vast majority just use a capacitive coupler and bridge rectifier. The LED array varies but the one I reverse engineered and simulated is a series combination of 8 parallel connected pairs of LEDs. I took apart a couple of other manufacturers devices and they were of similar design principle though with a different array configurations. Obviously these designs are aimed at just 240V AC operation and not compatible with 110V. The design you have is more flexible in that regard and I would expect to be better behaved.

    The bulbs, rated at 8W, were made in China by LumiLife. It seems there are two companies called LumiLife in China, one who sells in Europe and another (I think unrelated company) who sells into the USA and Saudi Arabia. The latter have more complex designs with downconverters. The company selling the products in the UK is called the LedHut and they have done very well out of importing and selling LED products; they offer money back guarantees and no quibbles about returns on the product life. And they did return my money when I complained but were not interested in my critique. I think they have a very good profit margin on the products!

    LED bulbs are generally very good with excellent power savings but I would recommend using a reputable manufacturer like Philips and also ensuring a free flow of air as close to the base of the bulb as possible. LED downlights are usually better as the power is much less and there is better heatsinking - I would still recommend Philips or some other European based company as manufacture though as they have better regard for safety features as well as the product life.

  5. #35
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    Hi,
    UK must set up a government run lighting industry to gaurantee jobs for Uk youngsters wanting to come into Electronics in UK.
    It is actually cheaper to design and maintain lighting products by UK designers rather than "subcontract" it all out to China.
    Only pure manufacture is cheaper in china.
    Uk is loosing its way, getting into huge debt, and will be a third world country within a decade if it does not sort this out.

    If you get a power supply or lighting product designed and manufactured in China, it is more expensive than designing and maintaining the design from Uk, ....but getting it manufactured in China is cheaper.

    -But UK is loosing design ability as we are swamping out our electronics industry with Far Eastern designs.

    UK Youngsters who come into this state run lighting industry will at some point leave and go on to fertilise the rest of the British economy with their government instigated skills.
    People who can design lighting power supplies can design power supplies for all other sectors too.
    Surely you agree with all this?

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