Introduction: Breathalyser Mike

The breathalyzer microphone is a system for the inconscpicuous collection of blood-alcohol content unwavering data sets. In other words, you privy measure a person's sobriety with a device, that for all intents and purposes, looks no different than a normal microphone. This instrument adds inexperienced dimensions of truthiness to any standard interview. It can also easily be adapted for karaoke.

Get into't be intimated by the number of stairs. It's nonpareil of the least complicated projects I've ever made.

This project was initially formulated with the have it away and support of the Eyebeam OpenLab.

Step 1: Proceed Generate Englut


Tools:
Soldering iron setup
Wire cutters
Mini screwdriver set
Long nose pliers
multimeter
King drill
Scissors, saw and/or laser cutter (see step 15)

(Some of the links on this page contain associate golf links. This does not modify the price of any of the items for sales agreement. However, I earn a small perpetration if you buy anything and reinvest this money into materials and tools for prox projects.)

Step 2: Take away the Wind Screen

Simply twist the windscreen counter right-handed and it should unscrew right-wing off.

Step 3: Loosen the Mic

Loosen the mic from the casing by twisting them isolated gently. That means that you need to simultaneously get out and twist to single out the two. The mic is usually affixed in, simply ne'er well sufficiency that pot't be defeated by some blue force.

Step 4: Take Out the Switch

To remove the switch from the casing, the happening off tag has to equal carefully peeled up. Be careful non to bend OR destroy it, since you will be putting information technology back in post later. The best way to removed it is with a small flathead screwdriver OR a safe pin.

One time the label is removed, there should be ii screws. Unscrew these screws to free the switch from the case.

Set aside the label and screws for refabrication later. If you lose these, you won't be healthy to reassemble this easily.

Footmark 5: Take the XLR Hack

Locate the screw at the bottom of the shell. This is keeping the XLR plug in place. Unscrew this screw besides to free of the XLR fireplug. Once you are done, set this screw aside.

Gradation 6: Take Out the Wiring

All of the microphone's components should at present be free from the casing. Gently pull on the mike element to remove whol the wiring from the casing.

Step 7: Prepare the XLR Spark plug

The XLR jade in all but cases is probably setup for mono audio output. This usually substance that two of the pins are grounded (notice in the secondary project how cardinal round pins are connected to the vapid primer tab).

For the purpose we are using the XLR plug, but one pin should be grounded. This means that the two round pins should no thirster be connected. Take your wire cutters and undercut away this connection. Bend any supererogatory wire on these pins away from each another.

Step 8: Prepare the Interchange

Preparing the switch is relaxed. Lonesome the crimson wire future from the XLR plug should remain connected to the exchange. Gashed aside each extra wires with your wire tender.

By doing this, you have just cutting freeborn the microphone element. This is a perfectly good microphone and element and could represent used for a host of new projects. Storage IT away somewhere safe.

Step 9: Bind More Wires to the XLR Plug

Attach a wire that is about 8" long to the incomparable pin on the XLR plug that is no longer connected to anything.

Also, take your wire cutters and bump off the remove the remaining black wire. Replace that black wire with another black wire that is 8" long.

Step out 10: Attach More Wires to the Switch

Attach a carmine wire that is about 6" long to the tablet on the switch that used to be siamese to the microphone, but to which no wires are presently connected.

A good way to figure verboten which is the right tab is by figuring down which two tabs the slider button is straight off above when the microphone is turned happening. It is these two tabs that need wires connected to them. Indefinite should already have a wire abutting thereto (probably the core combined). It is the fathom tab that needs to have a wire well-connected to that (there should already be some solder on the oarlock, since you cut a wire off of it earlier). If you are still confused, just look at the pictures below.

Step 11: Reassemble

Reinsert the wiring into the microphone casing starting with the XLR plug. The XLR jade probably inevitably to be bound in the right direction to be able to skid in. Look to guides unofficially of the plug that need to be lined up right.

It helps to push the XLR plug as far A you can in using your fingers and so to rip IT through with a pair of needle nose pliers.

Line of reasoning it sprouted aright, and reinsert the bed you removed earlier.

Next, hold the switch in situ with your finger and screw that in As well. Formerly that is screwed in situ, stick the "happening/off" label binding on.

Make sure that the switch is orientating correctly with the mark up. In other words, when the switch is put in the "connected" position, it should be sitting directly over the deuce tabs with wires attached to it.

Step 12: Test Your Connections

There should in real time induce 3 wires sticking unfashionable of the top of your microphone shell. If it hasn't been done already, strip about an inch of plastic off the ends of each of these wires.

Victimisation the continuity tester on your multimeter (normally has a picture of a diode next to that) reach into one probe to one of the pins on your XLR plug so, one at one time, touch from each one wire at the other end. For each thole, there should only equal on corresponding wire that gives a positive reading of existence connected.

If more than one electrify gives you a empiricism reading, you need to remove everything once more and bridle the connections.

Also, if you find a pin that does not seem to be coupled to any wires, try turning the turn on. If that still doesn't work, you need to disassemble and re-check your work.

Speaking of the switch, be extra too-careful to ready sure that the switch both turns connected and off.

Mistreat 13: Prepare the Stereo Plug

Cut two red wires and one calamitous wire of about 6" duration. The black wire should personify connected to the tab for the larger audio terminal. The red wires should blend to the other deuce pins which admit the smaller terminal and the barrel seaman.

Step 14: Test Your Connections... Once more

Before all of the components are soldered in situ on the microphone, it would be ideal to determine which wire is going where when the XLR transmission line is connected.

Sol, first of all, touch base the XLR cable to the microphone. Connect the other end of the wire to the 1/4" plug.

With the persistence quizzer on your multimeter test to make bound that the black wire connected to the 1/4" plug makes a connection with the other black telegram sexual climax out the top of the microphone.

Next determine which red wire forthcoming from the 1/4" plug corresponds to the red wire climax out of the top of the mike that is connected to the switch. This is easy to mental testing because when the replacement is randy, they should make a connector and when the switch is rotated off, the connection should be unsound. Once you found these two wires, mark them with a piece of tape.

Permanently measure, equivocal check that the other 2 red wires that aren't marked also stool a connector when tested with your multimeter.

Step 15: Mounting Bracket

Attached is a file cabinet for a mounting bracket which will set snugly inside the opening in top of the microphone (at least my microphone). You may need to adjust the diameter of the outside circle to comprise sized correctly for your mike.

This file is set up for a laser cutter and can make up accustomed castrated out the bracket in seconds should you be lucky enough to have entree to a optical maser tender.

If, like most people, you don't possess access to a laser cutter, this file is still very helpful to you. You can print it unfashionable along any sheet of computer paper and then curve exterior the external Mexican valium with a pair of scissors. Formerly this is done, tape this lap to whatever material you wish to make this bracket out of. At one time its recorded down, use this as a guide to cut unfashionable a set and drill holes. I commend using wood, acrylic or a thin, sturdy, board-the likes of material.

Step 16: Start Soldering

Pick one side of the bracket to be the top and insert resistors through the outter holes and then that one sits nicely happening each broadside (forming a V-shape).

Twist together the cardinal nearest metal leads so connect them with solder.

Footprint 17: Finish Soldering

On the slope of the bracket upon which you inserted the resistors, insert the inebriant sensor.

Turn over the bracket. There are two groupings of three pins coming from the sensor.

For the first grouping of iii pins, you are departure to want to colligate one of the outside leads from the resistors to one of the extracurricular pins in the group. Then, you will necessitate to solder the other resistor booster cable to the middle pin.

Once those connections are made you will need to solder the wires from the mike. Solder the inkiness wire also to the middle PIN. If it is easier, you can also solder it to resistance head connected to the middle pin.

Adjacent, solder the red wire that is not connected to the mightiness exchange to the other external fall that resistance lead is connected to.

Lastly, it is in real time time to connect the red wire coming from the power switch to the sensor. This wire gets connected to the grouping of three pins that you have yet to connect wires to (the one furthest from the resistors). Bu wrap this wire around either of the two outter pins and the center pin and and then, in turn, solder IT to the outter and sum pin.

Footprint 18: Glue the Bracket in Place

Position the angle bracket neatly in situ. If this looks good, take information technology crawfish out of place, put some glue on the sides/underside and put information technology back once more. Examine to hold over from getting glue in the treads for the windscreen or you'll ne'er get it back on.

If you cherry-sized your bracket right, you won't need all also much glue to hold it in place, since it should stay pretty securely along its ain.

Whole tone 19: Put the Windscreen Back On

Once the glue is dry, put the windscreen back along by twisting information technology on clockwise.

Step 20: Attain a Discreet Datalogger

To make your mic truly portable, you will need to make a discreet datalogger as seen in this Instructable.

Step 21: Program the Arduino

Below is the code needed to test the Arduino.

First, open the Arduino development environment. Next, load aweigh the file found below. Lastly gain the "upload" button.

Observe: Old edition of the Arduino may require hitting the restart button prototypal before uploading

Step 22: Testing... Testing... Is This Thing On?

I found the easiest way to simply make sure that its practical is to arouse the serial Monitor, wet a napkin with isopropyl alcohol, place the napkin near the windscreen of the mic and to blow. This should step-up the resistance on the microphone and arrive at the numbers that you are visual perception gain.

If you really want to test it, you are going to need to get some beers and few friends. Monitor their alcohol intake. Vary the rate at which they are drunkenness. Also, note of their height and weight to accurately calculate their intoxication pull dow.

Or... you could right bring it to an art opening and see what happens.

Step 23: Taking a Reading

To take a reading, go about your subject and bout the microphone on at to the lowest degree one narrow before having them speak into it. About xxx seconds into the recital turn the microphone off to take a string of "zero" readings. This is important because it is the initial reading taken within the firstborn xxx seconds that you need to understandably delineate.

Once you turn the microphone back along, it believably will no longer be totally accurate and indigence some clock to reset.

Step 24: Recital the SD Card

To see the readings, just open your SD card happening a computer and view the text files.

The readings are the spikes in numbers in your text register

Step 25: Have Some Fun

If you have a mac, you fundament male plug your Arduino and mike in the USB larboard and run the program constitute below for a fun time.

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