flyboy0681

Cabin light auto shutoff

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I rewired the supply line to the light switch from direct to battery to the sonalert buzzer + supply in the overhead panel. This way the lights can only be turned on when the master is on.

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After I ruined my battery leaving the cabin light on, I designed a circuit to keep the lights on for 10 or 12 minutes after the master switch is turned off. It is an electronic circuit with a darlington pair transistor set up. I have a couple of them made up. Naturally, they are not STCed, so would need to be installed as a minor modification by and A&P, or a reasonably talented hangar elf. Let me know if you want one, or I will be glad to give you the diagram so you could build your own. 

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11 hours ago, DonMuncy said:

After I ruined my battery leaving the cabin light on, I designed a circuit to keep the lights on for 10 or 12 minutes after the master switch is turned off. It is an electronic circuit with a darlington pair transistor set up. I have a couple of them made up. Naturally, they are not STCed, so would need to be installed as a minor modification by and A&P, or a reasonably talented hangar elf. Let me know if you want one, or I will be glad to give you the diagram so you could build your own. 

There's no way I could build one myself.

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18 minutes ago, ArtVandelay said:

I think it’s basically just a capacitor and relay, CMIIW Don.

It is not too much  more than that. But some. Getting (or designing) a timer good for 30 seconds or so is easy. Getting one to stay on for 10 or 12 minutes is more of a challenge. Basically, the power feeds into a capacitator, and when the power is removed, it then bleeds back through a resistor. Sizing the capacitor, resistors, diodes and the transistors to get the timing right is the problem. Thus the Darlington pair transistor set-up. And yes, it requires a relay to carry the power for the lamps.

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I bumped into my cabin light switch with my baseball cap peak when I unloaded after a Bahamas trip.  Got back to the hangar two days later and the battery was completely dead. Master obviously off as per shutdown checklist.  Couldn't understand it at all - until I eventually figured out what happened.  Luckily happened back home in my hanger.  Very easy to happen somewhere else .....

@DonMuncy mind giving me a diagram?  Be a nice little project.

Edited by pwnel

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1 minute ago, pwnel said:

I bumped into my cabin light switch with my baseball cap peak when I unloaded after a Bahamas trip.  Got back to the hangar two days later and the battery was completely dead. Master obviously off as per shutdown checklist.  Couldn't understand it at all - until I eventually figured out what happened.  Luckily happened back home in my hanger.  Very easy to happen somewhere else .....

With the cost of the timer and ease of installation, I consider this one of the "best bang for the buck" things you can do. I know that many people fly a lifetime without having the problem, but one battery is one two many.

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5 minutes ago, pwnel said:

I bumped into my cabin light switch with my baseball cap peak when I unloaded after a Bahamas trip.  Got back to the hangar two days later and the battery was completely dead. Master obviously off as per shutdown checklist.  Couldn't understand it at all - until I eventually figured out what happened.  Luckily happened back home in my hanger.  Very easy to happen somewhere else .....

@DonMuncy mind giving me a diagram?  Be a nice little project.

PM sent

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On 2/13/2020 at 11:03 PM, Gagarin said:

I rewired the supply line to the light switch from direct to battery to the sonalert buzzer + supply in the overhead panel. This way the lights can only be turned on when the master is on.

This and a flashlight. Problem solved.

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I wired my baggage compartment light switch with a 3-position rocker switch.  Middle position is off, One side is on all the time (should back seat passengers want to look for something in the baggage compartment) and the 3rd position is on, but the light shuts off when the baggage compartment door is closed.

john Breda

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Somebody in the 90s thought it would be a good idea to have it hot all the time...

It was a good idea, until they combined it with a super easy to turn on switch...

The switch gets bumped accidentally, and your 0.6 amu battery croaks...

Best regards,

-a-

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