Micro Radio Time Station Keeps Watch in Sync

The US National Institute of Standards and Technology (NIST) broadcasts atomic clock time signals from Fort Collins, Colorado on various frequencies. The WWVB signal on 60 kHz blasts out 70,000 watts that theoretically should reach the entire continental US. Unfortunately for [Anish Athalye], the signals do not reach his Massachusetts dorm, so he built this GPS to WWVB converter to keep his Casio G-Shock self-setting watch on track.

Not a repeater but a micro-WWVB transmitter, [Anish]’s build consists of a GPS receiver module and an ultra low-power 60kHz transmitter based on an ATtiny44a microcontroller’s hardware PWM driving a ferrite rod antenna. It’s not much of a transmitter, but it doesn’t need to be since the watch is only a few inches away. That also serves to keep the build in compliance with FCC regulations regarding low-power transmissions. Heavy wizardry is invoked by the software needed to pull time data off the GPS module and convert it to WWVB time code format, with the necessary time zone and Daylight Savings Time corrections. Housed in an attractive case, the watch stand takes about three minutes to sync the watch every night.

[Anish] offers some ideas for improving the accuracy, but we think he did just fine with this build. We covered a WWVB signal spoofer before, but this build is far more polished and practical.

200 mile RF transmitter (and high altitude balloon)

If there is one thing we like, it’s a fellow hacker so enthusiastic about his or her work that they write the article practically for us by including as much detail and information as possible.

In this two part hack, [Scott] wrote in to let us know not only about a high school built high altitude balloon, but also his $5 long range RF transmitter. The former is simply GPS and video data logged over the flight, but [Scott’s] specialty comes in the latter. A 74HC240 octal buffer is using to amplify the signal (Morse code) from an ATTiny44a with a 29MHz oscillator, producing a usable signal as far away as 200 miles.

It is low bandwidth, but if you’re looking for a simple transmitter in your project and need something with more power (and a smaller package), this might be the ticket.