1000 lumen caving light

[emesine]

Here are a few pics of a light I have been working on. My newest version is 1000 lumens ( about 12 times a 4 D cell halogen) fully waterproof, will run for 300 hours on low power, and costs about $140 to build. There is a single button switch on the lamp that cycles through the brightness settings. It runs off an 8.4 volt battery pack.

Now that I've ironed out the details, this is pretty easy to make. I'm trying to make this sort of technology open to all cavers. This is something anyone with a boy scout's technical ability can make. A 500 lumen version costs under $100 (you could do it cheaper) and can be made in a few evenings.

I'm thinking of posting plans if anyone is interested!

Andrew







This is my light compared to a 4 D cell halogen beam.

[NZcaver]

Nice looking light!

Feel free to post the plans. Are they anything like these which junkman just posted on this thread?

[FiddleCaver]

Plans would definitely be cool.

[emesine]

Here are plans to make the 500 lumen version. I'm still working out the details of the linear regulator for the 1000 lumen version. I've made two that work (based on a 334 chip), but EEs that I know shake their heads and groan when they see the schematic. I'm going to publish a good regulator (based on an op-amp) when I get the details ironed out. Allen, I suspect you want to see the schematic I am working on- I'd be happy to send it to you so you can fiddle with it. I'm pretty sure it will work, but I haven't actually built it yet!

Happy light building

http://www.emesine.com/light.pdf

Andrew

[FiddleCaver]

MOST IMPRESSIVE!!! Hah, I use epoxy to glue everything, and never thought about using it to encase my electronics. That's so freaking simple. My light has 12 screws holding 2 plexi lenses against O-rings, a magnetic reed switch, a plug from sure seal, and a battery encased in a flexible rubber sort of like the sten... All to ensure waterproofness, and I still worry about just how "waterproof" it really is. I guess you don't have to wonder about that though. Good work.

I am curious about your regulators, I've been wanting to design one based on an op-amp or a microcontroller but I just haven't had the time to sit down and mess with it.

[Stelios Zacharias]

How waterproof does the epoxy allow this set-up to be? Are we talking dunky waterproof or something more substantial?

I am not interested in official figures, but would such an epoxy set up allow the light to be submerged enough for a shallow dive?

(I know next to nothing about waterproofing so this may be a very stupid question)

[Ralph E. Powers]

MOST IMPRESSIVE!!! Hah, I use epoxy to glue everything, and never thought about using it to encase my electronics. That's so freaking simple. My light has 12 screws holding 2 plexi lenses against O-rings, a magnetic reed switch, a plug from sure seal, and a battery encased in a flexible rubber sort of like the sten... All to ensure waterproofness, and I still worry about just how "waterproof" it really is. I guess you don't have to wonder about that though. Good work.

I am curious about your regulators, I've been wanting to design one based on an op-amp or a microcontroller but I just haven't had the time to sit down and mess with it.

I'm thinking the only way to test water-proofness is the ole' bathtub test... get one of your lights (that you can spare) and turn it on and drop it in your tub of water and leave it for a little while. Then slosh it around a bit.

Either that or drop it in the washing machine and give it the ole' soak and banging around test.

[emesine]

The easiest solution would be not to cave dive. It's pretty dangerous anyhow. I am strictly forbidden from cave diving by my wife and other important figures to whom I owe some debt of love or obedience.

There is almost no airspace in the light, so it is pretty well completely waterproof already. If I were to take this underwater (again, I don't cave dive. If I didn't die in the cave, my wife would kill me herself when I got home), I would make two modifications:

1. As per fiddlecaver, use a reed switch embedded in the main epoxy of the light as the on/off switch. A reed switch is 100% waterproof, it is activated by waving a magnet a few cm in front of it. They cost less than a dollar from digikey. OF course then if you loose your magnet in the cave, you're in trouble.

2. Remove the glass faceplate. Instead of a faceplate, just fill in the reflectors with a very clear, bubble free epoxy. You'll loose some brightness, but now you are truly 100% waterproof, because there is literally no airspace at all for water to seep into the light.

Andrew

[FiddleCaver]

I'm thinking the only way to test water-proofness is the ole' bathtub test... get one of your lights (that you can spare) and turn it on and drop it in your tub of water and leave it for a little while. Then slosh it around a bit.

Either that or drop it in the washing machine and give it the ole' soak and banging around test.

I've tested them several times in the pool, sink, creek... I'm just a little paranoid. I had not thought of the washing machine, if one could survive that, I'd pretty much bet it would survive any cave.

[Realms]

we've had some electronic components encased in epoxy submerged in our underwater astronaut trainer for several hours at a time. So far I have seen no negative effects in the equipment.

[Stelios Zacharias]

http://www.emesine.com/light.pdf

This is a good guide to putting the light together, thanks for sharing it. The whole epoxy idea is quite appealing.

I noticed towards the end of this document that you have the power compartment (batteries, etc) also encased in an epoxy block - on the 1000 lumen model. What sort of batteries are these that you have encased in epoxy? How does one recharge them without compromising the waterproofness of the whole thing?

I have read (in the leaflet of the Princeton Apex for example) that batteries discharge potentially explosive hydrogen in watertight fittings. Is it safe to encase batteries in the epoxy?

Just some initial questions after reading.

[FiddleCaver]

I wouldn't be too worried about hydrogen discharge from those li-ion cells. I would be more worried about getting the battery pack's protection circuit soldered correctly and carefully, avoiding any cross wiring (Speaking from experience) because this can potentially cause an explosion. I assume you're using a protection circuit...

[emesine]

Yes, if you don't want your battery pack to explode, a battery protection circuit on the LiIon pack is a good idea. Most commercial packs are already wired with them.

According to the manufacturer, there must be an air space around LiIons in case they are overcharged/discharged and the batteries vent. If you look close in this design there are several holes in the epoxy where gasses can vent. I'm going to plug these holes with something nice and squishy like wax that will blow out easily. I've never seen a LiIon cell explode, I don't really know what would happen. I'd really prefer not to find out (especially underground!)

I haven't published the 1000 lumen design yet partially because I haven't really fixed this problem- how to protect the LiIons without sealing them completely in epoxy. Any ideas?

Andrew

[FiddleCaver]

I have my packs in 2 layers of industrial heat shrink tubing, then apply several coats of tool dip. It makes the pack waterproof and quite durable, yet it still leaves enough flexibility for some gas to escape.

[CAVERSCOTTM]

Here are plans to make the 500 lumen version. I'm still working out the details of the linear regulator for the 1000 lumen version. I've made two that work (based on a 334 chip), but EEs that I know shake their heads and groan when they see the schematic. I'm going to publish a good regulator (based on an op-amp) when I get the details ironed out. Allen, I suspect you want to see the schematic I am working on- I'd be happy to send it to you so you can fiddle with it. I'm pretty sure it will work, but I haven't actually built it yet!

Happy light building

http://www.emesine.com/light.pdf

Andrew

Sent you a email to see if you would send the parts. I do not want to order the wrong things.