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Thread: Bizarre simpledrive II driver problem

  1. #11
    Join Date
    Nov 2008
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    Cleveland Ohio
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    Here's an idea to solve this forever. Load switching. Make a circuit that hooks to a dummy load and switches over to the diode after a few seconds. This then absorbs spikes. Do the same on turn off. Thinking a dpdt on off switch. One side is power and the other is the switch circuit. One shot 555 and 4066? Then again zener can lock voltage. Is there a currrent version of a mov? I'm sure this can be engineered out.

  2. #12
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    Feb 2008
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    Northern Indiana
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    Quote Originally Posted by jors View Post
    Do you power with Lab PSU while adjusting? Which brand is your PJ PSU? I got 4 P73 killed by a chinese 'no brand' PSU months before...now all seems OK with Meanwell
    I set-up with a lab supply. The supply in the projector is a meanwell. Although, to be honest, I have had a few meanwell's go up in smoke in LED installations. Not sure if they were genuine meanwell? They were very sparse and cheaply built when I opened the ones that failed.

    Quote Originally Posted by kecked View Post
    Here's an idea to solve this forever. Load switching. Make a circuit that hooks to a dummy load and switches over to the diode after a few seconds. This then absorbs spikes. Do the same on turn off. Thinking a dpdt on off switch. One side is power and the other is the switch circuit. One shot 555 and 4066? Then again zener can lock voltage. Is there a currrent version of a mov? I'm sure this can be engineered out.
    I'm thinking an easier solution may me to add a low inductance resistor in series with the diode. Say the power supply = 15V and the Vf of 2 series blue LDs is ~10v. A momentary short on the driver transistor would put a max of 5V on the resistor (plus the drivers sense resistor). A 1ohm resistor would allow only 5amps to flow. Probably not enough to kill the diodes on a start transient.
    Last edited by logsquared; 07-10-2017 at 08:47.

  3. #13
    Join Date
    Feb 2008
    Location
    East Sussex, England
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    5,075

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    If this is the project I'm thinking of, I've got the other 10 drivers of the batch in a pair of projectors (used them this weekend just gone actually, still working fine)
    Although they did have a bit of leakage last year where I had to adjust the quiescent current (perhaps you recall the conversation BBE)
    http://www.facebook.com/SubsonicSystems
    http://www.frikkinlazors.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

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