For labor day weekend, I had some extra time, so I put together the direct conversion receiver from the first chapter of EMRFD. I made some small changes to the circuit and used the si5351/arduino combo as the vfo. The receiver uses a NE602 as the mixer and an LM386 as the audio amp. I connected it to my 40 meter dipole, but I wasn’t hearing anything. After playing around with it for a while, I put together a simple rf amp and added it to the input and that seemed to help.
I finally put together the SoftRock Lite II kit that I picked up a while back. The kit itself was a pretty fun build, but when I was done, I couldn’t get it working with either of the laptops that I had at the time. They both had those combo headphone/mic jacks and I tried in linux and windows and I couldn’t get either to work. The only other computer in the house with an audio line in port (that was in an operable state) was my media server.
Since the last post, I have set up a raspberry pi and connected it to the arduino over usb. I configured wifi on the raspberry pi and I’ve written a simple python script to control the rover. Now, I can ssh into the raspberry pi, launch the python script and I can remotely control the rover using the same keys from the arduino sketch (‘l’ for left, ‘r’ for right, etc.
In the last post, I replaced the steering servo with a standard hobby servo. Now I should be able to control the drive and steering with an arduino. For the drive motor controller, I am using a Pololu MC33926 motor shield with a 7.2v NiMH RC battery pack hooked straight to the shield. I plugged everything in, tweaked the example code from the DualMC33926MotorShield library and it worked like a charm.
I am currently waiting on parts from China to continue working on my radio receiver, so I thought I’d start working on a robotic rover. I’ve picked up several remote controlled cars from the thrift store and I have been meaning to turn one into some kind of autonomous vehicle that can roam around the yard. Here is what I am starting with. I think I paid $1 for this truck without the controller.
After I killed my homebrew upconverter, I went back to messing around with ads-b and dump1090. The little antenna that came with the rtl-sdr dongle worked okay, but I wanted to build a better antenna to see if I could get more range. I looked online and found quite a few pages on coaxial collinear antennas and I had everything I needed to build one, so I figured I’d give it a shot.