Lightbulb altimeter testing

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Dipstick

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I need some recommendations for making a lightbulb tester for my egg timer builds. I have been using igniters to test but want to save them...

I bought some cheap lights on Amazon thinking anything would work, but these don't. Any recommendations?
 

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rharshberger

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Good old incandescent christmas tree bulbs work fine, what you have there looks to be LED's any they have to have both a current limiting resistor and polarity correct to work (iirc). I have found in most cases the older style christmas tree bulbs take a bit more juice to light than ematches so if the bulb lights so will most ematches. I use different colored bulbs.

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jderimig

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I need some recommendations for making a lightbulb tester for my egg timer builds. I have been using igniters to test but want to save them...

I bought some cheap lights on Amazon thinking anything would work, but these don't. Any recommendations?
Your LEDs will work if you put a series resistor on them, anything from 100 to 1000 ohms should work. Also you need to get the polarity right, fortunately there are 2 options to try.

Throw the ones away you tried, you burnt them out.
 

cerving

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Another problem with LED's is that they might light dimly from the trickle continuity current, which is from 100 uA to 500 uA depending on which Eggtimer altimeter you have. Incandescent Christmas tree lights won't light unless you pump a decent amount of current into them, and there's no polarity to worry about. A package of 100 that you buy for a few bucks from a discount store at a post-holiday sale will last your forever.
 

boatgeek

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At least with the LEDs I used, I also needed a parallel resistor to get the continuity check to pass. It was something large, I forget how many ohms though.
 

UhClem

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The AltAcc manual recommends a Type 194 miniature bulb. Available almost everywhere.
 

heada

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pbahorich

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These worked well for me:
https://www.amazon.com/gp/product/B07T579FK7/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1
I just cut them off the wire and use different colors for each stage of deployment:
green: drogue primary
red: drogue backup
blue: main primary
orange: main backup
Having different colors allowed me to see that my drogue backup actually fired before my drogue primary during vacuum testing due to different manufactures philosophy on triggers.
As a result I rearranged things so my backup altimeter became primary for drogue and my primary became backup for drogue.
 

OverTheTop

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You can also get "grain of wheat" bulbs which are quite small. They can even be turned into igniters a bit easier than using Christmas tree bulbs if you want.

The Xmas tree bulbs are probably a larger electrical load, compared to the grain of wheat, and a better test of the avionics.
 

pbahorich

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There is a full writeup on a cheap and simple DIY vacuum test setup for altimeters here, as well as the colored light bulb approach I used:
 

Dan Griffing

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I need some recommendations for making a lightbulb tester for my egg timer builds. I have been using igniters to test but want to save them...

I bought some cheap lights on Amazon thinking anything would work, but these don't. Any recommendations?
I've used miniature Christmas tree lights clipped from an old string with great success. Each bulb has a resistance of less than two Ohms and glows quite brightly but without burning out.
 
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