On Oct 3, 2010, at 12:59 AM, Dr. Gerald N. Johnson wrote:
> The lamps could be in parallel. The schematic is badly drawn. Two on
> line vendors of lamps
> http://www.donsbulbs.com/cgi-bin/r/b.pl/1820|28v|0.1a~usa.html
> and
> http://bulbster.com/lightbulbs/eiko-1820bts-49790-p-2306.html
> claim the lamps are 1820 but two 1820 in parallel at 28 volts will
> draw 200
> milliamps and fry that 20 ohm 1/2 watt resistor with 0.8 watt
> dissipation.
After being the owner of what may be the last remaining box of #47
bulbs in Israel, I decided to look for other sources. I found that the
cost of shipping ranged from $13 to $35 for a box, while the box
itself ranged from $3 to $12.
I gave up and replaced them with LEDs. Super Bright LEDs
http://www.superbrightleds.com/
has LEDs that replace bulbs. They have a #47 replacement that works
on AC or DC and just goes into the socket. It has 180 degree
dispersal, so it works light a light bulb. Their white bulbs are
"daylight" colored so they are bluer than regular bulbs.
So far I've replaced #47's in Drake equipment, and used their 12 volt
bulbs in an Argo 509 and matching (405) amp. The Argo has 2 redish
grain of wheat bulbs for the dial and a socketed 12v bulb. I replaced
the socketed bulb with a white LED bulb, but left the grain of wheat
ones because they work, and are such a pain to replace (you have to
pull the font panel). Someday, I'll get energetic and replace them. :-)
For international buyers, they sent my first two orders in a padded
envelope for just over $5 in shipping. The third order was slightly
larger and sent in a box, which delayed it two weeks. :-(
Geoff.
--
Geoffrey S. Mendelson, N3OWJ/4X1GM
To help restaurants, as part of the "stimulus package", everyone must
order dessert. As part of the socialized health plan, you are
forbidden to eat it. :-)
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