Speech Recognition Geocache: Se Habla Español

Instructables user [jorgegunn] has put a unique spin on a recent geocache build by incorporating speech recognition and requiring that the “finder” knows the secret password to access the loot contained within. Although we won’t spoil the fun here, the techie spirit of the build was further bolstered by choosing a password fitting for any trekkie.

Despite utilizing an off-the-shelf speech recognition circuit kit, the majority of this hack was accomplished using parts available at local electronics and hardware stores. [jorgegunn] went to great lengths to make this hack accessible to any amateur hobbyist  and even includes links to relevant tutorials, schematics, and online parts vendors where applicable.

The actual speech recognition is accomplished with an Images Scientific Instruments model SR-06 circuit kit, capable of recognizing up to 40 different predefined words across multiple languages. Any time a correct match occurs, a value corresponding to the memory slot for that word is displayed on a pair of 7-segment displays. A separate decoder circuit based on a 74LS373 D-Type Latch and 4028 IC Decoder CMOS determines if the value being displayed constitutes a valid response and then drives a solenoid via a Darlington transistor in order to release the latching mechanism. Once opened, the device is simply pushed closed again to await its next finder- we are guessing that finding it might actually be the easiest part as judged by its size!

Although the real-world battery life has not yet been determined, a single coin cell for memory retention and a 9V battery used to drive the circuit and for latch release lasted through a full month of testing without any issues. Battery life could be extended almost indefinitely with a simple solar cell and rechargeable battery setup, but this would also obviously increase the likelihood of vandalism and/or theft.

We can imagine many different applications for such a device as-is including automated door lock  mechanisms and even access control to things such as the controls on a computer case.  It should also be fairly easy to increase the security by stringing multiple words together into a password or by instituting a “time out” period after a certain number of incorrect guesses.

Let us know of any other applications or build variations in the comments below and make sure to see how it all came together in the short videos after the break.

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Reverse geocaching Christmas gift box

This is the reverse geocache box that [William Dillon] built as a Christmas gift this year. He started with an interestingly shaped wooden box from the craft store. The clasp to keep it shut uses a servo motor on the lid with a wooden arm that grasps a screw on the base. As with the original geocache box, the Frustratomatic, and the smaller geocache, the box is designed to open only when in the correct geographic location thanks to the GPS module inside. That was a problem for [William] when a bug in his firmware locked the box during development while the key location was 1000 miles away. Luckily the box uses hinges that are attached from the outside with screws. We wonder how feasible it would be to use the mounting screws from the LCD screen to implement a coded emergency entry, using one as ground and the others as paths to microcontroller pins.

Reverse GeoCache puzzle gets downsized

[Markus] built his own reverse geocache puzzle box but on a smaller scale than the original. His is based around a PIC 18F2520 and powered by two AAA batteries. The user interface includes one button, a 16×2 character LCD, and a piezo speaker. The box unlocks itself when the GPS module inside detects the proper location on the globe. There is also a secret code that can be tapped on the button to unlock the box prematurely, and another to show the locations in which the user attempted to open the box. This build doesn’t leave much room for a payload, but [Markus] did a great job designing the board and making the components fit as efficiently as possible.

Frustromantic Box, a reverse Geocache

One of the best feelings in the world is when one of our posts inspires a fellow hacker to plan, create, and execute his or her own project.

[Russ] let us know about his Frustromantic Box which he gained inspiration from the original Reverse Geochache we posted about. For those out of the loop, the box is locked and will only open in a certain location. The current distance to the  location is displayed on the screen when a button is pressed, and usually there is a limited number of button presses (3 presses for those that know geometry, 50 for everyone else). As soon as the box is at location, it will open.

The Frustromantic Box uses an Arduino, classic HD44780 display, a servo, and the pièce de résistance EM406 GPS. All built in time to frustrate his wife for Christmas.

Reverse geocache puzzle


[Mikal] wanted to create an awesome electronic wedding gift for his friend who was moving to France. After experimenting with a few things, he settled on creating a puzzle box that would only open in a certain location. Since his friend introduced him to the Arduino, he fittingly used one in the design, along with a serial GPS module and a mini character LCD. The box itself is locked using a servo-controlled chopstick, which could theoretically be snapped if [Mikal] really screwed something up. To save battery life, he used a small Pololu module to provide power that uses only 0.01 microamps in standby, and can be shut off by the Arduino.

The box was designed to be mysterious yet self-explanatory. When the button on the front is pushed, the box comes to life for 3 minutes, displaying the distance away from secret location. Additionally, it warns how many tries are left: the button can only be pushed 50 times before it is sealed “forever”. In order to open the box, you have to be within 2km of the destination. Theoretically, you can narrow down the location to one of 2 points after 2 readings, but a less scientific approach would probably be a lot more fun.

This seems like an amazing gift, and the same concept could be repurposed into hundreds of other devices. For extra fun, he could have placed it at a geocache location.