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current limiting diode

Discussion in 'General Electronics Discussion' started by plumber, Oct 17, 2009.

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  1. plumber


    Sep 23, 2009
    Please dont laugh too much, the following is a note I sent off regarding a cld (diode) I attempted to use...I need help. In pipe fitting, almost everything is in line and parallel connections rarely effect the function of the main. I think this is where I am missing it. My beloved current limiting diode is a 2 terminal striped diode that is essentially a JFET with the gate shorted to the source. In the application that follows, can some one please tell me what to do to make it work? Thank you plumber.

    Hello, I recently purchased a current limiting diode, but it did not limit the current. I am sure the fault lies with me and not your product. I need to buy more, but first I must find out what went wrong. Please forgive the lack of proper terminology as I describe what I did: this is for electrolysis, in which I need to keep the current from climbing above 1.5 mA.
    30 volt dc unregulated power (wall adaptor) + output to striped end of CDL. (+) output from diode then goes through multimeter (in line) and then out to the (+) anode. - output from wall adaptor goes through (-) side of multimeter and then to the (-) cathode. Starting current was
    228u. As the process advanced, the current climbed past 2.88mA after the tenth hour. The CDL was rated for a current limit of 1.2mA .Stock #610-1n5299 / MFG PN 1n5299 (Central Semi Conductors) I will test the diode a little later and report back. How susceptible are these diodes to static discharge? I was reasonably careful, touching my grounded project box as I handled and soldered the diode in place. Didn't use a grounding strap. So please, tell me what basic circuit knowledge I messed up with? "series" / "parallel" did I need a Zen. diode or resistor somewhere? I know the set up was ultra simple...made sense to a plumber! Any input would be appreciated.
    thank you for your time
  2. Resqueline


    Jul 31, 2009
    So you got hold of a cld at last, not bad.
    That hookup sounds fishy to me, but I don't think the diode is damaged.
    Here's how I think it should be wired.
    PSU+ to the unmarked end of the CLD, the striped end of the CLD to multimeter red wire, multimeter black wire to electrolysis anode, electrolysis cathode to PSU-.
    If this doesn't fix the current then you could try it with the diode the other way around.
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