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Title: where the HECK can I got those tiny 6V light bulbs Post by: badbaud on August 23, 2010, 10:46:01 PM For the 50V reel reader cards. I really hate going to the distributors websites and searching for 6V lamps because I get hundreds of hits to look through and have not found this lamp yet. Where do YOU buy them?
Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: Neonkiss on August 23, 2010, 11:11:45 PM Are you looking for the 50V incandescent?
Or the 5V I/R? You threw me off with searching for 6V lamps.... either way,check Foxslots at the top of the page. He has them. Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: badbaud on August 24, 2010, 01:16:41 AM Those are 6V lamps not 50V lamps in the 50V reel reader cards. They put 5 of the 6V lamps (light bulbs) in series, plus a 470 Ohm resistor in series with that to drop the additional voltage.
Math: 6 x 5 = 30 so the resistor has to drop 50 - 30 = 20 volts. I'll have Larry W. call Barry F. tomorrow and find out where he gets his lamps. Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: Brianzz on August 24, 2010, 01:33:09 AM Make sure you let John Q. know what you find out
Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: badbaud on August 24, 2010, 01:36:55 AM Of course. Without John Q. there would be no customers... just you and me.
Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: Neonkiss on August 24, 2010, 08:15:21 AM badbaud,
Thanks, I forgot those are wired in series. # 680 lamps I found some hand written documentation in a book with a parts breakdown. and now John Q knows. :30- Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: badbaud on August 24, 2010, 02:22:35 PM Well, John Q. knows what the number is but still doesn't know where to purchase a couple hundred for repairs.
Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: stayouttadabunker on August 24, 2010, 02:28:14 PM Did you try China?
Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: Brianzz on August 24, 2010, 03:10:09 PM China has always been a little crowded for me.. a real sausage factory there.. may be Hong Kong?
Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: FOXSSLOTS1 on August 24, 2010, 04:25:49 PM If you are looking for the bulbs in the 50 volt E-series reader boards - I sell them.
Title: Re: where the HECK can I got those tiny 6V light bulbs Post by: badbaud on August 24, 2010, 11:36:57 PM And Larry knows where you get them. I'm his tech. Further research shows me that the replacement for the 780 bulb is the 7833 bulb AND that the 780 (and 7833) bulbs are 5V bulbs not 6V bulbs. Lets see... 5V x 5 = 25V for the 5 lamps in series. So the resistor has to drop 25VAC (lets talk RMS and not PEAK here). So a 470 Ohm resistor with 25 volts across it is conducting .0532 Amps through it and P = I squared times R giving us a minimum wattage rating of around 1.33 Watts. Probably why that 3 Watt resistor on the reader gets a little hot when the lamps are on. I use the 5 Watt metal film resistor when replacing this resistor. It is the same size and doesn't get as hot.
Back to the bulbs. All of the suppliers sold the 7833 lamp for over $1.20 each, Allied had the actual 780 bulb in stock but it was still over a buck. I am going to order a small sample of the lamps I found at Jameco Electronics to see if they will work. They have a 5V version of one with wire leads for under 50 cents each. |