Introduction: Discreet Pants Fly Checker

Picture of Discreet Pants Fly Checker

People are always wondering how it is that I make so many inventive things. This is normal day-to-day stuff for me. I just do it. I don't really know how to do anything else. What is more mind-boggling to me is how everyone else does those other things like clean their homes, feed themselves, and get dressed in the morning. These commonplace tasks that people take for granted I find utterly challenging. While there are so many things that I struggle with, one such task I'm particularly bad with is remembering to zip my fly back up after going to the bathroom.

The Discreet Pants Fly Checker was made with this in mind. Basically, this is a device that lets you discreetly check in public whether or not your pants fly is up. By pressing a button located in the watch pocket of your pants, a small pager motor alerts you to whether or not the zipper is up. Basically, the zipper of the pants was enhanced with two strands of conductive thread which  form a complete circuit when bridged. A small circuit board with a battery, button and motor attached then snaps into the watch pocket. Finally, when the button is pressed, and the zipper is closed, the circuit is completed and the motor vibrates.

How discreet you want to be about pulling your fly back up when it is down is up to you, but at least you do not have to be grabbing your crotch uncertainly all the time. That at least is a drastic improvement.

Step 1: Go Get Stuff

Picture of Go Get Stuff

You will need:

(x1) CR2302 battery holder (Radioshack #270-009)
(x1) CR2302 battery (Radioshack #23-802)
(x1) Vibrating pager motor (Radioshack #273-107)
(x1) Tactile switch (Radioshack #275-002)
(x1) 1.75" round PCB (Radioshack #276-004)
(x1) Round tube pen
(x1) Spool of conductive thread
(x1) Pants with watch pocket
(x2) Sewable snaps

Step 2: Battery Holder

Picture of Battery Holder

Solder the battery holder to the 1.75" round PCB, such that the holder itself is on the same side as the copper solder pads.

It may be helpful to tin (apply a small amount of solder to) the pads that you intend to solder to ahead of time.

Note: the attached circuit diagram applies to the next 10 steps.

Step 3: Button

Picture of Button

Solder the tactile button swithc to the (designated) top side of the 1.75" round PCB

Step 4: First Snap

Picture of First Snap

Strip the insulation off about 3" of solid core wire.

Pass it through two holes in the circuit from the copper side on through to the back.

Slide the button snap onto these wires so that it lies flat on the backside of the circuit board.

Bend the wires over and pass them through the other mounting holes on the button snap, and then back through the board.

Pull the wire taught.

Solder the wire to both the copper pads and button snap.

Trim away any excess wire.

Step 5: Ground It

Picture of Ground It

Solder the first snap attached to the ground terminal on the battery holder.

Step 6: Second Snap

Picture of Second Snap

Attach the other snap in a similar manner to the other edge of the circuit board such that they are about 1.25" apart.

Step 7: Solder

Picture of Solder

Connect the second snap to one of the terminals on the tactile switch.

Step 8: Trim

Picture of Trim

Take apart a pen tube and cut a section that is slightly larger than your vibrating motor.

Step 9: Insert

Picture of Insert

Insert the motor into the pen tube.

Step 10: Glue

Picture of Glue

Glue the motor into the pen tube while making sure the motor can stil spin.

Once that is dry, then glue the pen tube to the circuit board.

Step 11: Solder the Motor

Picture of Solder the Motor

Solder the motor's ground lead to the switch terminal opposite to the terminal connected to the snap.

Solder the motor's power terminal to the positive terminal on the battery holder.

Step 12: Insert

Picture of Insert

Insert the battery with the '+' side facing up.

Step 13: First Thread

Picture of First Thread

Cut 3' of conductive thread and fold it over onto itself. Pass the creased end of the thread through the eye of the needle to quadruple the number of threads. Tie the thread ends together with a knot.

Starting from the top, count down six pairs of zipper teeth, and make a stitch in the center of this pair.

With the same length of thread continue stitching between every other set of teeth until you reach the top.

Once at the top, using a running stitch, sew along the pants seam until the thread is over the watch pocket, and then sew down into the pocket.

Leave the thread attached to the needle for sewing the snap base on.

Step 14: Second Thread

Picture of Second Thread

Thread another needle with quadruple strands.

Stitch between the opposite set of zipper teeth, while being very carefully to keep the threads from touching or overlapping. If the threads do get close, they can later be tacked apart using a non-conductive thread preferably matching the color of the pants.

Make another conductive thread trace following the seam, and again not touching the other trace.

Finally, stitch this thread down into the watch pocket, also leaving the needle connected.

Step 15: Finish Snaps

Picture of Finish Snaps

Sew the based of the snaps into the watch pocket approximately 1.25" apart.

Step 16: Connect

Picture of Connect

Insert the circuit board into the watch pocket and snap it into place.

Step 17: Use

Picture of Use

Whenever you want to check if your fly is down, simply press the tactile switch. If it does not vibrate, find a discreet place to go to pull your fly back up.


Likeswater (author)2017-01-02

I like it! Very wear-able!

parisusa (author)2013-09-15

I agree with Chopper Rob (Jul 30, 2013) :)

chall9 (author)2013-07-30

I had the same problem with a favourite pair of jeans, the zip would work its way down. My solution was to put a 1" split key ring through the hole in the zip pull toggle, which both helps pull up the zip by hooking in my index finger, and the ring is then hooked over the copper button before putting through the button hole. The fly can't open without undoing the top of the jeans first (a sort of chastity belt mod as well).

JoshHawley (author)chall92013-07-30

I hate to admit it, but low tech is often the best solution.

KomaToast (author)JoshHawley2013-07-30

Low tech is best, KISS, Keep It Simple Stupid.
One could just attach a spring to it so it zips itself up.
Just keep a good grip on it while taking care of business.

ilpug (author)KomaToast2013-08-08

That brings bear-traps to mind.

How about no?

dwream (author)2013-08-06

Wonderful! This is almost the ultimate in wearable technology! For those - like me - who do not remember to "discreetly check", how about tweaking your invention to send a text message to the wearer if the zipper remains down more than a few minutes?

raykholo (author)2013-08-05

Cool. When I saw the first picture, I though the round PCB was a photocell, and I go to myself, "This guy has a photocell behind his fly to check if light will get through?

Good thing that wasn't it.

angelabchua (author)2013-08-03

Bravo. Bravo!

randofo (author)angelabchua2013-08-04


relaxing (author)2013-08-01

This is without question the single most practical e-textiles project I have ever seen.

DGerman (author)2013-07-31

Well thought out. Especially with snaps. Nice presentation. Now replace the switch with an LM555, 2 resistors and a capacitor and have it check every 30 seconds for you!

srilyk (author)DGerman2013-07-31

Pretty awesome idea but then you'll start getting ghost vibrations like your phone provide ;)

oldanalyst (author)2013-07-30

This is a fun project and I am tempted to try it but it falls into the Rube Goldberg approach to doing things. A very simple fly checker is either your eyes or your hands. No batteries required.

tig1 (author)oldanalyst2013-07-31

Ya I had high praise for the effort, buuuuuuut "Rube Goldberg" did flash to mind, and how about using,Arduino, or a pc with quad core CPU 16 gig ram an bluetooth to and nex gen robotics to keep your violin case shut........ or maybe just a pair of button fly LEE's... but whats the fun in that :)

tn. (author)oldanalyst2013-07-30

unless you suffer social anxiety which basically results in paralysis - you're afraid your zipper is down, but if someone sees you checking they might think you're a pervert. the resulting situation is the donkey dilemma (positioned exactly equal between two bales of hay, the donkey was unable to make a decision and starved to death).

Treknology (author)2013-07-31

An interesting idea but, like Winston Churchill, I don't have to worry about a dead bird falling out of the nest.

K4nyix (author)2013-07-31

Great idea, made me laugh a bit because of this simple ingenuity. On the other hand, I'd have rigged the thing so that it vibrates when the fly is down only, such as if you press the button on accident, or you've got something compressing your pocket (may it be your little nephew on your lap or rush hour in the metro) it doesn't buzz incomfortably.

Tin Man (author)2013-07-31

Could be worth building it into a custom belt-buckle.
When the zipper is done-up, (bar is at the top), a 2.5mm plug attached to the bar by a short length of cord plugs into the bottom of the belt buckle. The trousers are then washable without forgetting to take buzzer from pocket.

ElectroFrank (author)2013-07-30

As someone said, the problem is, you still have to remember to check.   So how about this:

The sensor circuit activates a motor in the waistband which winds up a cord which pulls up the zip automatically ?

Include a switch to turn it off when you undress, and a push button to deactivate it whilst tinkling.

(And a panic button just in case anything gets . . . ah . . . caught.)

vintammy (author)2013-07-30

I think this is an excellent idea. I had the embarrassing moment of walking around a tourist destination for about two hours with my fly open. Had it not been for a woman who told me to zip up my fly, I would not have realized. I was totally embarrassed, so I endorse this entirely.

shizumadrive (author)2013-07-30

oh no! did i put the battery in the pants fly checker! Nice item though I could have used it today

gulnar (author)2013-07-30

You made my day with this i'ble :D

alfeel (author)2013-07-30

duuuude that's so complicated, I use a bloody simple keychain ring or a paperclip!

mslaynie (author)alfeel2013-07-30

It's not for keeping the zipper zipped. Instead, it's to check to see if you forgot to zip after using the restroom without being obvious and checking out your crotchal area. :D

tn. (author)alfeel2013-07-30

which still doesn't address the whole "remembering to use it" issue.

dworley (author)2013-07-29

You wrote a lot of words but I know you only made this because you wanted to find a use for that goddamn pocket.

randofo (author)dworley2013-07-30

I used to have a pocket watch that I kept in that pocket. One day I shattered that pocket watch and never found a suitable replacement.

NateHoy (author)dworley2013-07-30

You mean the "USB Thumb Drive Pocket"?

Someone needs to make a thumb drive in the shape of a lighter or fob watch. Just sayin'

hornbadoing (author)NateHoy2013-07-30

That is actually a watch pocket. commonly referred to as a "Fifth pocket"

Chopper Rob (author)2013-07-30

I just like the idea vibrating pants. (someone had to say it)

skylossobaka (author)2013-07-30

makes me wonder if you have an idea for a device that just stops you from being embarrassed by having your zipper down...

NateHoy (author)skylossobaka2013-07-30

It's not a device. It's just called "getting old and not wasting as much time on what other people think". Works great.

While there are some side effects, it sure beats the alternative (not getting old).

tig1 (author)2013-07-30

Gota say I do like it.on several levels , your had a problem, thought out the problem, designed a solution , followed through and built the device that would solve the problem. A vast majority of people have ideas but they never follow through.. that's what separates the Nikola Teslas from the average person. I hate Like hell to quote Edison, I despise the man but he said "Genius is one percent inspiration, ninety-nine percent perspiration" and you my friend in my eyes embody that quote.. Brilliant.

nonobadog (author)2013-07-30

Dude, you need to get a girlfriend. She would check it for you and she doesn't need batteries, at least not for that.

kcbaltz (author)2013-07-30

Wouldn't some kind of poka yoke (fail proofing, look it up :-) ) for this be better? Something that would prevent you from closing the waistband without also zipping up? Or what about removing the pull tab from the zipper so you have to use the keyring of your car keys to pull the zipper up and down. I don't think you'd forget that you're walking around with your car keys hanging in front :).

mikeasaurus (author)2013-07-29

As someone that checks their fly regularly for this exact reason, I support this.

studleylee (author)mikeasaurus2013-07-30

I do a motion like this: Stretch with arms in air, the bring my hand down the abdomen, then casually run the finger under the zipper flap to check. Don't really care if anyone sees. The worst was when I trailed toilet out the back of my pants. Only a night guard at Qualcomm saw me as I went to my car.

kibukun (author)2013-07-30

Always wondered what that pocket is for... Hey! You should present this idea to a company. (with a patent on it of course) If you suggest them to start adding the sensor circuit to their jeans with a plug in, you can add a jack to yours and sell them next to the jeans!

Exocetid (author)2013-07-30

In your video, you stated the phrase "really awkward." Good grief, I could not have summed this Instructable up better myself. Bravo!

e5frog (author)2013-07-30

I wonder if that thread always connect properly to the zipper?

If the zipper was part of the top button it wouldn't be possible to button your pants without it being zipped and it wouldn't be possible for it to slide down.

Perhaps a magnet on the moving part of the zipper and a vibrator circuitboard with a magnetic reed switch would be a quicker and moveable solution. It would start vibrating if it was turned on and magnet wasn't close enough. With another type of detector perhaps a magnet wouldn't be necessary.

sm7x7 (author)2013-07-30

Awesome idea! Good job, very useful stuff.

Kikapoo (author)2013-07-30

A simple motion sensor would be a huge improvement. It could set off the alarm if the pants are moving with the zipper undone. There absolutely is no reason the owner should move with the zipper open.

rsucgang (author)2013-07-30

One suggestion to make this totally waterproof (for accidentally leaving this in the pants while doing laundry) is to encase it in resin. It may take a while before the battery runs out, so probably make a few extra ones! :)

nkapon (author)2013-07-29

thats cool, now you need to invent a device that will remind you to remove it from the pocket before throwing the pants to the laundry...

shadowyblade (author)nkapon2013-07-30

Yes, that was my first thought. I started reading this, and almost immediately worried that if I used this I would accidentally wash this the first day I used it.

msdrpepper (author)nkapon2013-07-30

That was my thought, speaking as a representative of the Mommy sub-species who usually washes the family clothes. My procedure is low-tech - I just check over the menfolk in the house before they leave, and tell them "Remember to close the Barn Door..." And that usually has them checking all day!! ;)

caitlinsdad (author)2013-07-29

I believe you are only addressing the symptom and not modifying the root behaviour. I would have went with the taser circuit with the two probe rails as the zipper sides. If your junk is ever hanging out....yup, it only takes one time to remember whether you last had it up or down. Now how to explain it to the paramedics on the scene, I dunno.

kidNeutrino (author)caitlinsdad2013-07-30

although... one could argue with an alternate placement of the vibrating motor, you could setup a reward loop system for having the zipper in the preferred public position.

With this solution you may as well remove the offending member and the need for a zipper...........urg!

About This Instructable




Bio: My name is Randy and I am a Community Manager in these here parts. In a previously life I had founded and run the Instructables ... More »
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