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Thread: Jonny reviews lack the Hold Up Time test.

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    Quote Originally Posted by CM Phaedrus View Post
    our Taipei lab to verify it's consistent.
    And if you could actually do that....there is no point in building your half baked solution because you already have the equipment.

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    I'll just air ship every sample to Taipei then if I want to test hold-up time.

    Seriously Paul, it's not that complicated.

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    His idea is valid. But I think only a couple samples need to be validated. Not every one. I mean, if you have a few that are consistent, is it not safe to assume that others wouldn't be?

    That's all I plan to do. Do a few units on the SM-5500, then do them again on the Chroma and see if the results are similar. If they are, I'd feel comfortable with the measurement being accurate.

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    Yup. That's how I plan to do it. Once I get this set up, tested, and working, I'll ask Taipei to make sure to do hold-up time tests on their next batch of samples to me and give me the data, then when I get them I'll run my own tests for comparison. 2-4 units should do it.

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    I whacked out the LM431 precision voltage section. Easy as pie. With proper resistor values this should be able to get down to 5.00V +/-0.01V or better up to a few mA.


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    Ok, HV section is done, I believe. One of the harder parts conceptually; the analog and logic will take more math, but aren't as much of a pain as isolating a mains switching relay while still having enough power to drive it. But it's best not to fuck with mains electricity, and coupled noise would definitely screw with the analog circuitry. So it has to be done. Took a few revisions, but I think I've got it.




    If I can get an optocoupler that can drive a few mA of current, and a fast enough relay that doesn't need more than a few mA of current, I may be able to nix the A3 bridge rectifier section, and remove that transistor. But for now it's best to include it in case I need it.

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    Quote Originally Posted by Travis View Post
    You don't have to buy a Chroma AC source to make a consistent hold-up time test.
    All you have to do is to make an MCU-based small device which cuts off the AC input (with a relay or solid switch) at a specific phase angle, for example, at the positive or negative peak of Vin. It may also generate a pulse as the trigger of osilloscope.
    It will only need a few hundred bucks, and a few weeks of work.
    It doesn't need a trigger for the scope since you can trigger the PSU PS On signal. Also you have to give a delay to the circuit in order to have the PSU running at full load for at least 5-10s. If you don't give any delay then the PSU will shut off immediately right after it starts. Or at least put a switch for normal and hold-up test operational mode.

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    Quote Originally Posted by crmaris View Post
    at least put a switch for normal and hold-up test operational mode.
    That's what I'm planning to do. A switch to activate the comparator.
    It's been a hard day's night and I've been working like a dog.

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    Quote Originally Posted by CM Phaedrus View Post
    I'll just air ship every sample to Taipei then if I want to test hold-up time.
    The product is already closer to Taipei. And if CM has the ability to so thoroughly test product, then why do they not do it already? Why do they have an employee with not EE degree or experience in NIST building half backed equipment?

    Seriously Paul, it's not that complicated.
    Actually, building, calibrating, and validating test equipment is MUCH more complicated than you know. I hate to break it to you, but there are reasons WHY these things cost what they do.

    Quote Originally Posted by CM Phaedrus View Post
    Yup. That's how I plan to do it. Once I get this set up, tested, and working, I'll ask Taipei to make sure to do hold-up time tests on their next batch of samples to me and give me the data, then when I get them I'll run my own tests for comparison. 2-4 units should do it.
    You can not pull 2-4 samples from a lot of thousands in one location, then pull 2-4 samples in another location and compare to two sets to establish the accuracy, precision, and resolution of your two pieces of equipment. Before you do this I would strongly encourage you to employ someone who understands at least sampling and statistical analysis methodologies if not development and production of test equipment as well.
    Last edited by Spectre; 03-21-2014 at 09:48 AM.

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    Quote Originally Posted by CM Phaedrus View Post
    For the switching device, there are some issues.

    Relay -- Most likely. Medium switching speed. Difficult to isolate. Inexpensive.
    Triac -- Unable to switch off on command. Not usable.
    Mosfet -- Fast switching speed. Easy to isolate, inexpensive. Only blocks in one direction, so needs to follow a bridge rectifier.
    IGBT -- Fast switching speed, not too difficult to isolate, not too expensive. More efficient than mosfets. Only blocks in one direction, so needs to follow a bridge rectifier.
    GTO Thyristor -- Ideal operation, but only available in >1kV and >100A ratings, cost >$200
    Relay looks better to me.
    It's been a hard day's night and I've been working like a dog.

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