How to build a Tetra PAPRa m12 Battery Controller (v2)
Quick Synopsis
The Tetra Powered Air Purified Respirator requires power to function, and the m12 battery controller provides that power for these models. The controller consists of internal circuitry, a potentiometer to adjust fan speeds, a cable to connect to the fan box, and a port for a Milwaulkee M12 Battery to be inserted.
This build differs from the v1 version in that it uses a custom-built circuitboard to remove many of the difficult steps of the build, add a battery charge indicator, and a separate power port for use in a car. If you cannot get the custom board (found in this repository: https://github.com/tetrabiodistributed/PAPRA-PCB), then please refer to the v1 version of this guide.
Parts Required
This build will require printed parts, purchased parts, and several tools. Here is a picture of all the components used in this build:
3D Printed Parts
These parts should be printed at 0.2 spacing:
| Part | Quantity | Material | Supports Required? | STL File Location |
|---|---|---|---|---|
The Body | 1 | PLA | Yes | |
The Lid | 1 | PLA | No | |
The Plate | 1 | PLA | No | |
The Knob | 1 | PLA | No |
Bill Of Materials
You will need these components. Prices fluctuate, and so are not included here. Alternative versions can be sourced, and we welcome edits for tested alternatives.
| Count | Description | URL | Number in Package |
|---|---|---|---|
1 | Circuit board | 1 | |
1 | 2Pack Upgraded 3.5Ah M 12 Battery for Milwaukee 12V Battery Lithium XC M 12B Batteries | 2 | |
3 | Washers | Should come with the board | 3 |
3 | Nuts | Should come with the board | 3 |
Recommeded Tools
These tools are recommended. URLs are for tools purchased and used in the building of the prototypes:
| Description | URL |
|---|---|
4-3/4 In. Bent Long Nose Pliers | https://www.harborfreight.com/4-34-in-bent-long-nose-pliers-63819.html |
A hex screwdriver for the m4 screws | |
X-acto knife | https://www.amazon.com/Xacto-X3201-N0-Precision-Knife/dp/B00004Z2TQ |
A deburring tool | |
A 10mm socket wrench |
Build Instructions
Building this version of the controller is more a matter of ensuring that the Controller Box was printed cleanly and all support material is properly removed. If holes for various componets are not big enough, then do not hesitate to use the deburring tool to increase their size:
Separate the light pipe from the board:
Seat the board into the Controller Box:
Place the light pipe onto the board:
Place the Controller Plate into the battery socket of the Controller Box, then a washer, then screw in a nut. Note that the washer and nut will secure the Plate in place, but aren’t meant to do anything other than prevent random objects from falling onto the board:
Screw the Nut in place using the socket wrench:
Place washers and nuts on both external components of the Controller Box, and tighten with the socket wrench:
Place the Knob onto the potentiometer, and twist to turn on. If there is a charged battery in the Controller, you should see the lights in the light pipe:
Snap the Lid in place. Note the orientation; snapping the lid in in the opposite orientation may cause the lower lip to break off:
Congratulations! You have built a Tetra PAPRa M12 Controller Box v2!
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