Over the past few months I’ve been developing a couple of Arduino projects.
Remote Power Control via SMS
The first is a remote power device so I can turn power on or off via SMS. This has been working now for several months. The project is based on one found on the Little Bird Electronics site. It uses a remote control power board from Jaycar electronics. Cat No MS6150. No mucking around with 240 V connections to the Arduino required. It does need a 12 V power supply though to drive the remote control circut. It uses optoisolators as switches to essentially press the buton on the remote.
When the GSM card recieves an SMS the Arduino reads this and raises the volate at the relevant optoisolator for 1 second. The SMS is in the format of #(port)(on/off) eg #a0 for port a off. The code maintains the state. It responds with an SMS to the phone number that it reads from the SD card. The code is to be found here Remote Power
Web interface to follow.
The final assembly, the SMS modem, the driver shield, the outside box.
Remote Temperature Monitoring
I have an LX200 acf which has a number of draw backs. The one that annoys me the most is lack of thermal stability. Given an hour to settle down and focus when ever the temperature drifts for more than a degree the focus goes out. I’ve done all the critical focus calculations and I’ve tried all the automated refocusing (which I can never seem to make work with 100% accuracy) using MaximDL. So I gave up. What I did do was build a small project with a couple of arduinos and Zigbee boards. My observatory is only a few metres away from my house, but the brick walls play havoc with standard wireless comms. The Zigbee gives me a radius of about 800m, walls included. The circuits are pretty simple. The telescope end has a temperature probe with LCD display and Xbee Pro. The device on my wall above my TV (so I can see if the temperature changes more than a degree) looks very similar but only has a LCD, and Xbee receiver mounted on and Arduino.
Pushing the red button resets the Set Temp to be the current temp on both the local and remote devices, when the temperature differerence is more than a degree the LCD display backlight is turned on and off every 5 seconds. Drives you mad when trying to watch TV. Time to go and refocus.
Temperature sensor from Freetronics, installed in the case.
Email me if you want the source code for the arduino project.