Geocache box with extra challenge

Yes, geocaching is still live and people enjoy this activity. GPS (or other) accessible to anyone who have at least a smart-phone. The idea is simple – you need to find a cache according to GPS coordinates. Usually this is hidden storage box with log book with sometimes additional treat. In order to make things more challenging, Cliptwings constructed a puzzle box powered by Arduino. The puzzle is a hangman game which has to be played and won in order to open the box. Controls are pretty simple – by turning knob you can select a letter and with single button you enter it. Arduino generates five random words to be guessed, and if most of them are not guessed – box remains locked. To in safe side, battery is … Continue reading

Opening garage door with fingerprint

There are still majority garages that can be opened with regular key. This is probably least secure way of protecting property – especially with standard locks. As you may know, most of standard locks can be picked in a minute. In order to be more safe, better install more secure lock with sophisticated key or go with electronic based system. Joebarteam have shared his instructable, where he built a fingerprint lock system for his garage. The basics of electronics is built around Arduino micro which reads electronic finger print scanner through serial interface. A bunch of limit switches ensure that closed, opened rood is detected correctly, also there are few fail-safe mechanism implemented that makes system power efficient and even safer. Mechanical lock is moved with stepper motor and seems … Continue reading

Monitoring three phase power usage with Arduino and keypad shield

This project is second iteration of DIY Life. Previously he has built a single phase power meter using similar technique. He wanted to keep things very simple, os he used only non-contact current measurement only by using Talema AC1030 current sensors on each phase line. They are capable of capturing 30A nominal and 75A maximum current. In order to measure power accurately a voltage measurements should be taken. But for sake of simplicity, voltage is only taken as 220V. The only focus is to measure current correctly which depends on burden resistor selection and measurement drop voltage through Arduino analog input. Input current then must be calibrated with known load. Rough estimate can be made with 100W light bulb. If you are considering building this three phase power meter, be … Continue reading

Arduino based high altitude balloon data logger

One of the more interesting experiments you can do above surface of earth is fly balloons in to stratosphere. Fun thing is that whole experiment isn’t very expensive and can give tons of fun. Probably most expensive thing here is balloon itself. The other parts can be used as you desire. Spaceshark have shared his experiment and build details on his instructable. He used Arduino Uno for logging various basic sensors detecting latitude, longitude, altitude, wind speed. He wanted to keep things simple and self contained, because at heights above 60000 ft some sensors start failing, e.g. GPS. Batteries are also another issue due to cold air above. He used authentic Arduino to make sure it works bellow -40 degrees Celsius. Fake ones can fail even at 0 degrees. Same … Continue reading

Simplest Attiny85 based watch

We are used to see different kinds of DIY watches. Some of them try to stuff lots of functionality, other make fancy time telling format or simply mimic smart watches. But why not build a watch that only tells time in a simple manner. This Attiny85 watch is what it does. Schematic is very simple and straight forward – Attiny85 microcontroller, 12 LEDs, push button, three resistors and coin cell battery. Such simplicity allows building small watch shaped PCB where all components are fit to look nice and light. Since microcontroller comes with only 5 I/O pins (excluding reset), LEDs are connected using smart Charlieplexing method that allows saving pins for simple I/O tasks. The only shortcoming of this watch that time is counted using microcontrollers internal clock which may … Continue reading