Re: 7904 Switch Lamps

Craig Sawyers <c.sawyers@...>

Horizontal mode switch = 670-1639-00

A and B bulbs = 150-0057-01
These are 7153AS15 "selected". The manual for 7904's above s/n
B26 gives a generic number of 17AS15 for these bulbs. Both
numbers are rated at 5 Volts and 115 mA.
Armed with that crucial information, I found that Farnell part number
315-9334 is a 3mm diameter 6.35mm long bulb, with a rating of 5V 120mA and a
20,000 hour lifetime. Price is 30p(UK) - so say 50c. And you have to order
10 off.

Or, here is an identical rating one. 5V at 115mA, same size as above,
Farnell part number 328-868. 37p each and minimum quantity of 5 off.

Alternatively try using a white LED. These drop 3.6V at a maximum of 30mA,
so a series resistor is necessary. Part 941-852, 3mm diameter 5.4mm long
and cost ?2.75. Probably only need 5-10mA for the same brightness as the
incandescent bulbs, so a tiny 150 ohm 1/8Watt resistor should do the trick.

Incidentally, Stan's figure for 50,000 hour ifetime works out at 8 hours a
day, 200 days a year for 30 years. Or if left on 24/7 they would burn for
nearly 6 years. Bet not many have blown, and used ones probably have many
good years left.


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