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Allen Brtadley pilot light question

Started by Don Lancaster April 2, 2014
Some allen bradley pilot lights or lighted pushbuttons accept a 110 vac 
input to drive a 6 volt 1966 incandescent pilot light. One example is 
their 800T-PB16.

The stepdown circuit appears to be something of a mystery and not a 
transformer as infinite resistance is measured on the 110 vac lamp 
terminals. And using a capacitor alone for a bulb drop is really dumb 
because of possible surges destroying the bulb.

At any rate, if a modern LED replacement for the 1966 is used, the load 
current will be much lower.

Will their circuit handle this, or will the LED blow out from overvoltage?

-- 
Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml   email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com
Don Lancaster wrote:

> > Some allen bradley pilot lights or lighted pushbuttons accept a 110 vac > input to drive a 6 volt 1966 incandescent pilot light. One example is > their 800T-PB16. > > The stepdown circuit appears to be something of a mystery and not a > transformer as infinite resistance is measured on the 110 vac lamp > terminals. And using a capacitor alone for a bulb drop is really dumb > because of possible surges destroying the bulb. >
Does the unit still work? I know some definitely had a TINY transformer in the back of the fixture, and the windings must have been made with insanely fine wire. So, I'd check to make sure the unit isn't actually defective.
> At any rate, if a modern LED replacement for the 1966 is used, the load > current will be much lower. > > Will their circuit handle this, or will the LED blow out from overvoltage? >
I can't imagine they used any serious electronics in 1966 for this purpose. (Or, is 1966 the bulb number? But, I can't find one of those.) Is there any possibility this unit has the wrong lamp in it? If it was for a neon lamp, it would have a series resistor, and would appear open circuit with the neon bulb in place. Jon
On 4/2/2014 12:12 PM, Jon Elson wrote:
> Don Lancaster wrote: > >> >> Some allen bradley pilot lights or lighted pushbuttons accept a 110 vac >> input to drive a 6 volt 1966 incandescent pilot light. One example is >> their 800T-PB16. >> >> The stepdown circuit appears to be something of a mystery and not a >> transformer as infinite resistance is measured on the 110 vac lamp >> terminals. And using a capacitor alone for a bulb drop is really dumb >> because of possible surges destroying the bulb. >> > Does the unit still work? I know some definitely had a TINY transformer > in the back of the fixture, and the windings must have been made > with insanely fine wire. So, I'd check to make sure the unit isn't > actually defective. >> At any rate, if a modern LED replacement for the 1966 is used, the load >> current will be much lower. >> >> Will their circuit handle this, or will the LED blow out from overvoltage? >> > I can't imagine they used any serious electronics in 1966 for this > purpose. (Or, is 1966 the bulb number? But, I can't find one of those.) > Is there any possibility this unit has the wrong lamp > in it? If it was for a neon lamp, it would have a series resistor, > and would appear open circuit with the neon bulb in place. > > Jon >
Oops. It was a GE 1866 bulb. Lights up just fine, so the circuit still seems to work. Not very bright, but incandescent with a strong green filter is not very efficient. -- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com Please visit my GURU's LAIR web site at http://www.tinaja.com
Don Lancaster <don@tinaja.com> wrote:
> On 4/2/2014 12:12 PM, Jon Elson wrote: >> Don Lancaster wrote: >> >>> Some allen bradley pilot lights or lighted pushbuttons accept a >>> 110 vac input to drive a 6 volt [1866] incandescent pilot light. >>> One example is their 800T-PB16. >>> >>> The stepdown circuit appears to be something of a mystery and not a >>> transformer as infinite resistance is measured on the 110 vac lamp >>> terminals. >> >> Does the unit still work? > > Lights up just fine, so the circuit still seems to work.
They seem to have two kinds of transformers for this. <http://www.ab.com/en/epub/catalogs/12768/229240/229244/2531083/Accessories.html#183040> One is exactly what you'd expect: two 120 V gozintas, two 6.3 V comesoutas - 800T-N326. The other kind has *three* 120 V gozintas and two comesoutas, and either has a relay (800T-N296) or some diodes (800T-N920N) inside. This seems to have something to do with providing a "lamp test" input that's independent of the "regular" input. http://www.ab.com/en/epub/catalogs/12768/229240/229244/2531083/Typical-Wiring-Diagram-s.html If you have the three-gozinta kind, you have to pick the right two gozintas for the ohmmeter. I think. Matt Roberds