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Jeff Wisnia
 
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Default Bulb Out Indicator circuit

Jeff Klein wrote:

so, can you suggest something for me that WILL work...





snipped

Awright, so for now, let's forget about relays, wall warts and LED's and
get back to basics here.....

Here's something that could work, and it's probably the lowest parts
count/cost solution, but no warranties on it or guarantees that it'll
satisfy all code requirements. (My advice is worth what you're paying
for it. G)

A 40 watt bulb will draw about 0.35 amps at 115 volts. If you Google
around and look at the specs of various automotive bulbs, you should be
able to find a (preferably) 6 volt or a 12 volt bulb rated to draw just
a bit more than that current. Get one of those bulbs.

If you put the 40 watt and low voltage bulbs in series across 115 vac
the automotive bulb (your "indicator lamp") should light to a little
less than full brilliancy, but only drop the voltage to the 40 watt bulb
by 5 to 10 volts, so the 40 watt bulb will produce close to it's normal
heat output.

A little experimenting should get you there....Unless my approach gets
screwed by the turnon surge of the 40 watt bulb blowing out the
automotive bulb. If that happens, get back over here and I'll give you a
more complex solution guaranteed to work.

Howzatt guys?

Jeff


--

Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"My luck is so bad that if I bought a cemetery, people would stop dying."