12 Volt Helmet Mod Guide

[Skippy[TK]]

I wanted to pimp out my Anovos bucket and add all the bells and whistles. It is a space helmet after all. I added adjustable fans, hearing assist and room for upgrades all while keeping everything contained within the bucket and on 1 battery. After months of experimenting, and trial & error, this is where I ended up.

 

 

 

 

General Mods

First I painted the inside of my helmet with black truck bed liner. I used that to help add a little rigidity to the bucket, its textured so things will adhere to it better, and it looks cool.

 

I ended up using a hardhat helmet liner. I tried the tactical helmet pads, but it just didn't work for me. The hardhat solution is perfect.

 

I took out the lens and cut them to shape. I then got Tee Nuts from home Depot, bent down the sharp bits and glued them to the inside of the bucket. I could then use screws to attach the lens.

 

 

To keep the helmet exactly where it needs to be on my head and stop the bobble-head look that some troopers have, I cut the nose bridge off of a pair of dollar store safety glasses and glued them to my TK lenses. All the helmet weight is on my head, the nose bridge just keeps my head locked in place.

 

 

 

Electronics

Here are the overall components and schematic.

 

 

Here are the schematics. I will explain each part bellow. The blue lines show each of the different components.

 

 

Battery

 

This is a 12 volt (12.5 actually, 2A, 3500mAh) battery that I got from Amazon.com used to power string lights, (https://www.amazon.com/gp/product/B007RQW5WG/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1)

 

I got it because its small, relatively light, but most importantly is has 3 cells in it. I realized that I was able to tap into each cell individually to get different voltages from it.  I’m able to get 12.5 volts, 8 volts and 4 volts with a common ground. This was an amazing discovery, because I was playing with different voltage regulators, but they are bulky inside the helmet and create heat. Also opening the enclosure and using just the battery shrank the size of the battery.

 

 

Inside the battery enclosure was a printed circuit board used to charge the battery. The circuit board monitors all 3 cells as it charges, so I had to cut the 4 connections, and install a 4 pin connector. So instead of the circuit board attaching directly to the battery cells, it goes though the connector first. You don't need the circuit board to use the battery, only charge it. It just so happened that the leads off the battery are 12.5v, 8v, 4v and a common ground. Perfect for what I need!

 

To charge the battery I just attached it to this make shift adapter and use the provided wall transformer to charge it.

 

 

Fans

 

I wanted very quiet, but powerful fans. I found I was very limited at what was available with 5 volt fans. So I found these 12volt blower fans that where the size I wanted. (https://www.digikey.ca/products/en?keywords=bfb04512MD ). They where on the expensive side at $20 each, but they were perfect for my needs.

 

I placed them inside the helmet blowing up beside the mic tips as seen below. My chin sits comfortably between them. One of the reasons I put them there was in was a good place to mount them for vibration reduction. The more I can reduce the vibrations, the quieter they will be. 

 

 

I made small adapter plates (from scrap styrene) to be able to mount them inside the curved helmet. I purposely left one side open so it can wiggle and absorb some of the vibrations.

I glued the adapter plates in the helmet, but used Velcro to attache the fans. This is partly for extra vibration reduction, but mostly to be able to easily take them out if they need servicing.

 

 

 

 

Adjustable Voltage Regulator

 

To control the fans I decided to make an adjustable voltage regulator in order to turn them down or off. I got all the parts to make my own at a surplus store for maybe $3. I used the following schematic, which is all over the Internet. You need a LM317 voltage reg, 0.1uF capacitor, 240 ohm resistor and a 5k pot. I later found out you and buy pre-made ones on ebay for $1.50. I ordered one just to test it out. It works just as good, but because it’s on a printed circuit board, it has a much larger footprint then the one I built.

 

 

Two VERY IMPORTANT things to note about this regulator is:

1) At full power it works great, no issues. When it’s turned down, and lets say the fans are running at 30%, the LM317 will produce heat and it gets fairly warm (that power has to go somewhere). I bent out a heat sync and I mounted flush inside of my bucket as seen bellow (it's the silver sheet metal part). For the very rare occasions I turn down the fans, the heat sink will solve that problem. 

2) One of the biggest problems people run into when using one battery to power fans and a hearing assist is electrical noise. You can hear the static and buzzing in the headphones caused by noise from the fans. A filter in the system can help fix that. I discovered that this voltage regulator acts as a filter and it solved that problem for me.

 

 

 

 

Hearing Assist

A didn't know if I would actually use it, but I decided to go for broke and install it anyways. This came with a lot of challenges, including electrical noise, RF interference and power issues. But I got it all figured.

 

The basic board is a very nice project board that I got from amazon.com for $14 (and a backup form a surplus store for $12)  (https://www.amazon.com/gp/product/B0006HJSLE/ref=oh_aui_detailpage_o09_s01?ie=UTF8&psc=1) The board takes about 2 ish hours to put together, it comes with great instructions and the full schematics which was super helpful when modifying it.

 

The board runs at 4.5 volts, but it can take 5v no problem. However I get 4v or 8v off my battery. I decided to use the 8v with a step down to make sure the board always gets its 5v. To step down the voltage I soldered in a LM7805 voltage regulator. It creates a constant 5V, I then soldered connector wires to it. Similar to the Adjustable voltage Regulator, the LM7805 produces heat. However the hearing assist draws almost no current (I measured it, but forgot the number. Its something like 10mA) so heat didn't end up being an issue.

 

Next was the hardest problem to solve, the RF noise. If you use a wired microphone, this is a non-issue for you. I wanted to use a wireless microphone from amazon.ca (https://www.amazon.ca/gp/product/B01DNJKUI6/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1). This wireless microphone gives off a signal that the receiver picks up. The hearing assist AND mic cables also liked to pick up a lot of noise from it, in the form of a loud hissing/buzzing.

 

Using regular wire to extend the mics from the board wasn't an option. I tested several cables (shielded wire, twisted pairs, Shielded twisted pairs, etc) and I surprisingly found that regular XLR microphone cable worked the best by far. It picked up no noise, it was black and flexible (perfect for the inside of the bucket, because some of the other cables was really stiff), and cheap at $0.10/foot at the surplus store. The only annoying thing was the cable had a braded shield. It was annoying to cut wile not damaging the wires or drain wire (the cable that runs with the shield for grounding purposes).  I also added a connector in the cable so I could swap out the mics. If you do this, make sure to not only connect the 2 leads, but the drain wires as well to help shield the system. I used JB wield as a strain relief for the mic cables at the board and on the mics, as pictured bellow.

 

 

I now had to shield the board. I used 2” heat shrink around the circuit to protect the components from shorting. I then used some copper ribbon I got at the surplus store for $5 ish. I wrapped it like a gift and soldered it together. I also soldered the two drain wires from the mic cables and the common ground from the power to the copper shield. This may have been overkill, but it works. I then wrapped the whole thing in another layer of heat shrink just to protect it all. RF interference is now a thing of the past.

 

 

During my experiments, I damaged the mics that came with the kit, so I had to order a new set. I ordered 5 different types, just to try them all and experiment with them. The biggest obstacle here was all these mics are grounded to the negative lead. I wanted an independent ground to help with RF noise.  Some mics you were able to scratch off the ground jumper with a knife and solder onto that. I ended up liking these noise canceling mics the best, but I will need to experiment with others at different troops. https://www.digikey.ca/product-detail/en/cui-inc/CMP-5247TF-K/102-1729-ND/1869989

 

 

To mount the mics, I did what everyone else does.  I took the ear caps off the helmet and drilled a hole behind them. I drilled tiny holes in the ear cap so when replaced the sound can go it. After a fresh coat of paint, you don't see the tiny holes. To mount the actual mics, I used rubber grommets.  This made it so I can easily swap out the mics, and the grommet act as a shock absorbent and dampener. So when someone taps your helmet, you don't hear it in the mics as much.

 

 

To hear things, the headphones work but there is room for improvement. I tried using small speakers (from an old ski helmet) inside the helmet instead of headphones, but they just produce feedback. For now I have these $17 headphones  (https://www.amazon.com/gp/product/B00V0JYQ50/ref=oh_aui_detailpage_o09_s04?ie=UTF8&psc=1). To pull in the headphone cable once the helmet is on, I attached the wire to a $5 retractable badge holder (https://www.amazon.com/gp/product/B01G1EY1Q2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1). Once the helmet is on, it’s comfortable. This system works, but hopefully I can find a better alternative to these headphones eventually.

 

Battery Indicator

 

I wanted to put a battery indicator in the helmet to keep an eye on the battery. I came up with 2 easy solutions.

Option 1: at $14 its the more accurate solution. (https://www.amazon.com/gp/product/B01LQ7MT4K/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) It gives a very accurate reading, however it's a little on the large size, and its always on. I epoxied a switch to it so I can turn it off so it doesn’t light up the inside of my bucket when I am wearing it.

Option 2: is $16 but better for what I need. (https://www.amazon.com/gp/product/B01E0U0JW4/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1). This indicator isn’t made for this type of battery, so there is a roughly 15% error on its read out. However, its small, waterproof, and when activated it only stays on for 30 seconds before turning off.  As long as I am aware for the 15% error, it’s not a huge issue for me.

For testing I use option 1, but I have option 2 installed inside the bucket.

Note: You attach the indicators to the 12V on the battery.

 

System as a whole

 

This may seem like a lot of stuff, but I got it all to comfortably fit inside the helmet. I’ve ran a few tests and troops since installing it and it all works great. I’ve ran the whole system for 10+ hours straight (with different fan speeds) to see how long the battery would last for. I got bored and stopped the test after a little over 10 hour mark, so I know it will run for at least that long.

 

I didn't weigh the helmet before, but it now only weights 2.4lbs with everything installed. I also made sure to balance the helmet when installing everything. The battery is mounted about 1 inch off center to help balance it on my head.

 

I used connectors on every component, and Velcro with a little hot glue to install them. So if anything needs to be serviced or upgraded, its all removable.

 

I used a large switch for master power switch, and mounted it where I could easily reach it while fully suited up incase of an emergency.

 

[Johnny Cab[TK]]

Wow! If you ever want to sell this rig, I'll buy one.

 

My signature has better things to do than sit here and let you read it.

[ukswrath[Staff]]

Yee Haw! Nice 

[Airborne Trooper[501st]]

Nice! I love to see different electronic builds. 

[Skippy[TK]]

Yee Haw! Nice 

Thanks Ukswrath. You where part of my inspiration to do this project.

[ukswrath[Staff]]

Thanks Ukswrath. You where part of my inspiration to do this projec

 Love it

[Big Deal]

[Kouri]

I'm fairly certain your pack's a mis-named 11.1v nominal pack using three 3.7v nominal 18650 batteries (full charge is about 12-12.6v, but batteries aren't supposed to be rated at their topped-up voltage). That probably explains why the second indicator is off by about 15% - you'd probably have better accuracy with an 11.1v lithium-ion or lithium-polymer voltage checker. Something like this perhaps: https://smile.amazon.com/dp/B06Y1HVR53/

 

As far as I can tell, the battery pack's protection circuit was left inside the pack's old case to use as a charging adapter. That should help balance things during charging (since the voltages are probably a bit uneven splitting off the two cells for 7-8v to the 5v regulator), but that still leaves you with three unprotected lithium-ion cells inside your helmet, which is a safety concern.

 

If you want to keep the batteries in the helmet, I'd suggest permanently wiring the protection circuit back to the cells and only using them with the full 11-12v line. Your 5v regulator looks to have a 25v max, so you're fine feeding it more voltage, though it might give off more heat.

 

Alternatively, if you can find some way to insulate these from moisture, a 3x18650 holder (like this: https://smile.amazon.com/dp/B071ZQ2X2T/ ) and three *protected* 18650 cells would give you the same amount of power in the same amount of space while also giving you the option to swap batteries if you happen to run down mid-troop. If you want to cut down on space/weight, you could also use a 3xAA battery holder with three protected 14500 cells.

[ukswrath[Staff]]

1 hour ago, Kouri said:

I'm fairly certain your pack's a mis-named 11.1v nominal pack using three 3.7v nominal 18650 batteries (full charge is about 12-12.6v, but batteries aren't supposed to be rated at their topped-up voltage). That probably explains why the second indicator is off by about 15% - you'd probably have better accuracy with an 11.1v lithium-ion or lithium-polymer voltage checker. Something like this perhaps: https://smile.amazon.com/dp/B06Y1HVR53/

 

As far as I can tell, the battery pack's protection circuit was left inside the pack's old case to use as a charging adapter. That should help balance things during charging (since the voltages are probably a bit uneven splitting off the two cells for 7-8v to the 5v regulator), but that still leaves you with three unprotected lithium-ion cells inside your helmet, which is a safety concern.

 

If you want to keep the batteries in the helmet, I'd suggest permanently wiring the protection circuit back to the cells and only using them with the full 11-12v line. Your 5v regulator looks to have a 25v max, so you're fine feeding it more voltage, though it might give off more heat.

 

Alternatively, if you can find some way to insulate these from moisture, a 3x18650 holder (like this: https://smile.amazon.com/dp/B071ZQ2X2T/ ) and three *protected* 18650 cells would give you the same amount of power in the same amount of space while also giving you the option to swap batteries if you happen to run down mid-troop. If you want to cut down on space/weight, you could also use a 3xAA battery holder with three protected 14500 cells.

 

I pretty certain you lost 99% of the audience by line three lol. Welcome to the FISD. Personally speaking it's always a pleasure to have others here with technical electrical knowledge.

 

 

 

[Kouri]

Ah, I spend most of my time with the lightsaber groups where the electronic knowledge is more commonplace. 

 

The short version is, as nifty as this setup is, the way the battery pack is disassembled and rewired makes it a fire hazard at the base of the wearer's skull.

 

The board in this photo is likely the battery pack's protection that prevents the cells from pushing too much electricity,  and shuts them off if they get too hot or the voltage drops too low. With the board separate,  this setup has three big unprotected lithium batteries stuffed inside the helmet. 

 

 

Something simple like letting the charge drop too low can damage the cells to the point they won't hold a charge anymore.  Or something more serious like a short from a loose wire or some other bridge might cause the cells to start pumping electricity and heating up until they damage whatever happens to be inside the bucket at that time. 

 

I'm not trying to be overly critical of Skippy's work.  This really is a very nice setup, and I'm sure he's taken great care of it so it hasn't cause any problems. I'm just suggesting tweaking the power supply to make it safer.