Fab Key Finder – explore

10 Questions about KeyFinder

1) How will the Key Finder be powered?

The Key Finder will be powered through batteries.

2) What makes the Key Finder unique?

The Key Finder is unique because if your keys are lost the design will flash a light and make a noise to alert you to its location.

3) Who is the Key Finder intended for?

The Key Finder is intended for an older audience, since children don’t typically have keys. Also, those who are older tend to have a busy schedule making it easier to misplace their keys.

5) Why is this project helpful? Fab Key Finder, the user will no longer go through the struggle of having no clue of where their keys are located.

6) What are the expenses of this project? Affordable, one time pay, and abundant.

7) Can this project be improved in the future? There’s always room for improvement

8) Where would this project be the most helpful? This project is most helpful in a more home-base setting because it’s the most typical place where people tend to lose their keys.

9) How long does this project last? This project is estimated to last for life, like most products you’ll just have to change the battery, LED, etc when it comes time.

10) Can this project help those with disabilities? Yes, because if you’re blind you can hear your keys, and follow the sound. If you’re deaf you can see the light of where your keys are.


5 Keywords to google:

  1. Lost Keys

  2. Key Locator

  3. Key Finder

  4. Missing Keys

  5. Key Misplacement


3 Examples of products that have parts like

1. KeyRinger → Light, Sound

2. Men Kind Key Finder → Key ring, Light, Sound

3. Magic Key Finder bling → Fun shapes of keychains, lights, sound


3 DIY projects to “steal” from/

1. When the phototransistor is stroken by IR light it conducts and the voltage between the 1Mohm resistor(arbitrary) and the phototrans drops from VCC to lower values. When the voltage drops lower than VCC/3 the 555 is triggered and goes high (from 0 TO VCC). The amount of light that strike the phototrans necessary to bring his collector to VCC/3 is determined by the resistor (Vdrop = Icollector * R , so , if Vdrop= 2*VCC/3, the resistance needed to set the threshold on current is R=2*VCC/(Icollector*3)). High sensibility phototrans would need a smaller resistor, and weaker phototransistors higher value resistor, you can also use a trimmer to set the on threshold level with precision. The time of phototransistor isn’t critical. The 555 has high current capability and can drive various devices, such as Bipolars, relays, bipolars+relays, mosfets, mosfets + totem pole , or give a logic output (see pic).


2.Whistle Key Finder method1 →  use a band pass filter to do the work. It works well, but it suffers a lot to adjust the resistors values because it depends on those values to determine the various parameters of the filter. So it can hardly be built on a small piece of board to reduce its size. [ http://www.thinkcreate.org/index.php/whistle-key-finder/]

3. Whistle Key Finder method 2 → second design uses a different principle. It uses a Phase Lock Loop to catch the tone of a whistle. The PLL can catch a certain frequency in the background noise. And only the parameters of the VCO are essential. So a single potentiometer to adjust the oscillating frequency will do and other components have a high tolerance of inaccuracy. [http://www.thinkcreate.org/index.php/whistle-key-finder/]


Internet sites with technical information

1. For the light→

SuperBright White LED           (Size isn’t that important, I had some 1.8mm ones left over from the Lego flashlight)

Small switch                              (I used these)


PCB mount battery                   (I used CR2032 ones which could be considered a bit big, but will last practically forever)

Soldering iron

Solder (natch.)

Helping Hand (shameless plug: How to make a Helping Hand)

X-acto saw

Breadboard (optional, see step 1)

Electrician’s tape (to make a rudimentary casing, more on this later)

site: Instructables

2. For the sound →

Hook Up Ez Connectors

Hook Up The Ground Wires

One Side Of Red

Second Red Goes On Lever


site: Instructables

3 Pros, 3 Cons about this project.

Pros→ Never lose your keys again

           Non expensive

           Light Weight

Cons→ What if you lose your Finder, like where the button is?

             Small LED lights may need to be replaced often

             May not be convenient to have to replace batteries on my own

Leave a Reply