Thursday, November 13, 2014

Our stab at a line follower robot

Found this old post that I somehow forgot to publish:

I and a couple of people from Illutron are running three workshops about robotics. One of the projects we are presenting is a line follower robot. We have chosen this since making a robot capable of following a black line on a piece of paper presents a number of good hardware and software challenges for the worksop participants.
This is our first version the hardware.
The robot is laser cut from 4mm HDF board and consists of a flat chassis driven by two hacked servos. A top structure is added to carry batteries and various sensors.
A curved structure at the back acts as the 3'rd wheel.
Good traction is achieved by gluing sand paper to the wheels.
The sensor is made from layered HDF board.

Minimalistic APRS transponder beaten by the internet

When starting the minimalistic APRS transponder project the goal was to make a semi-disposable APRS transponder costing less than 28 Euro (~35USD).
After spending many nights designing a VHF transmitter from cheap easily obtainable parts the price landed around (for the transmitter) 13.5 Euro (16.75 USD). This was not including about 1 hour of assembly time. All seem good but then I found this module on the Internet for 11.12 Euro, including shipping. Not only was it cheaper than I could ever build something myself but it was also a fully programmable VHF tranceiver and had 1W output.
I have now decided to base my APRS tranceiver around this module and use the left over money(!) on a more powerful processor.

Here is a picture of my initial prototype. Schematic and source follow shortly.

Friday, November 7, 2014

APRS transponder now with 1W output

Did some more work on the minimalistic APRS transponder. Made a test circuit board that allowed for adjusting component values. It now output 1Watt at 7.2V
UPDATE: Some pins have changed so this schematic is NOT compatible with the code posted earlier
Updated code HERE
Added a voltage regulator for 2LiPo cell operation.
Here is a quick video of my test setup transmitting 1W.