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Author Topic: Correct zener diode to use in auto ignitor? Brad Allen Jedi Master Film Handler Posts: 688 From: Evansville, IN, USA Registered: May 2000 posted 05-31-2008 12:33 PM                     Just replaced a Kneisley rectifier with a Xetron (IREM). Now the lamp auto ignitor in the lamphouse won't fire. I'm sure what I need is to put in a lower voltage zener diode on the autostart board. What would be the proper one? No load voltage measure's 78.5 volts from the rectifier. Thanks.  |  IP: Logged Sean McKinnon Phenomenal Film Handler Posts: 1712 From: Peabody Massachusetts Registered: Sep 2000 posted 05-31-2008 02:07 PM                        I would go with one around 65-75 Volts DC. The important thing is that you have a value low enough to allow the autostrike to activate with an IREM but not so low that you have trouble lighting the lamp due to inadequate open circuit (no load) voltage.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 05-31-2008 03:14 PM                     It depends on the lamphouse. Usually you want the open circuit to measure about 25 to 30 volts above the zener voltage. So somewhere around a 50V zener would be a good first try.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 05-31-2008 08:30 PM                        Brad: use the same value as your other, identical, set up. Louis  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 05-31-2008 08:33 PM                     The zenier you use must relate to the voltage rating of the relay as well  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 05-31-2008 09:46 PM                     I agree with Dave; 48Vdc is my suggestion.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 06-01-2008 10:28 AM                     I've always used 48 volt with older Irem's. Newer Irems have much higher no-load dc and you will require a higher voltage zener for those...around 60 volts give or take a few volts. Be sure to a zener rated at 5 watts!!! Mark  |  IP: Logged Brad Allen Jedi Master Film Handler Posts: 688 From: Evansville, IN, USA Registered: May 2000 posted 06-01-2008 07:49 PM                     quote: Louis Bornwasser Brad: use the same value as your other, identical, set up. Louis I would, but I don't recall what diode I used and I can no longer read the numbers on that diode. UV is dastardly. I do recall it took some trial and error to get the right one the last time. Thanks for the replys.  |  IP: Logged

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