It’s taken a while, but I finally have my JGRO CNC machine built and running. I spent a bit of time investigating a lot of ground noise on my stepper drivers. I’m using three Gecko G251 stepper drivers for the 3 axes of the machine. Turns out their step and direction inputs are not isolated, so with 3 drivers sharing the same logic ground, decent currents can flow between them. The fix involves adding a 100 ohm resistor in series with each logic ground connection, which reduces the unwanted ground currents. In hindsight, it would have been better to use drivers with isolated inputs, or a specifically designed 3-axis driver board. Continue reading
This is a very specific project, but I’m writing about it anyway in case someone has the same problem. I own an old boat, with an old switch panel that has old circuit breakers. Needless to say these particular breakers are not made anymore, but they still work well. Except the levers have a nasty habit of breaking. Continue reading
Here is a good idea I saw for cheaply monitoring engine temperatures. If your boat engine has ever overheated (like mine has) you will be a little paranoid about watching the temperature. I found some cheap digital thermostats on eBay and mounted them in a enclosure. The temperature probe wires needed extending, and I wrapped them in heat shrink for extra protection. I strapped one to a metal elbow in the cooling circuit, and the other to my exhaust, just after the raw water is injected. They can be powered from the engine ignition and will display the temperature of the probe. With a few buttons, you can programmed the thermostat to trigger its relay if the temperature goes beyond normal operating range. The relay is connected to a buzzer, acting like an over-temperature alarm. Works great!
UPDATED 09/08/2016. Following on from the last project, where I broadcast NMEA GPS data to iSailor, I wanted to send wind measurements as well. The mast in my Westsail 32 was out, and it was a perfect time to put a new wind vane on. The app iSailor now has an unlockable wind instrument display, meaning I could channel the measurements straight to it. Alternatively I could also send the data to a laptop running OpenCPN. Firstly I needed a wind vane to mount. In the same mind as the excellent Freeboard project, I decided to use a Peet Bros. Anemometer to mount at the top of the mast. The unit seems extremely reliable and simple, having only two magnetic reed switches inside. The timing between the switch pulses gives wind direction, and the frequency of pulses gives wind speed. It really doesn’t get much simpler than that, and this set-up only requires three wires to be run up the mast (eg. an audio cable).
Posted in Projects, Sailing
Tagged anemometer, arduino, iSailor, NMEA, sailing, wind, wind direction, wind instrument, wind speed, wind vane
If you have been using the iPad app ‘iSailor‘ for navigation (as I have), you may have seen the option to unlock NMEA positioning support. NMEA-0183 is a standard protocol used to communication marine information such as depth, speed, position etc. Most off the shelf GPS modules use this protocol as well. So I investigated how I could get my non-GPS enabled iPad (ie. non-cellular) receiving GPS data from another source.
To enable further projects, I decided a while ago that building a CNC router would be a great idea. This would allow me to cut wooden bits for projects and engrave circuit boards. I decided on the tried and tested JGRO plans, available for free on CNCzone.com. The JGRO design is mostly made from MDF, which is cheap and easy to cut at home. It also features metal pipes and skate bearings for the linear rails, which are simple and cheap but subject to slight flexing under load. Still, for a cheap home built machine, this is not too much of a problem. Continue reading
Having recently purchased a Hobie 14-ft catamaran, I have been having fun out on the water, but also wondering how fast I’ve been going. To give myself some idea, I decided to make my own instruments using an Arduino, LCD and GPS.
My first prototype is shown, displaying the speed in knots (0.0), the current compass heading (111°), the time, number of satellites (07), and the battery voltage (412mV). If you add on an OpenLog from Sparkfun, you can save all the GPS data to a flash card for viewing on a computer later. Best of all, it’s really quite easy to make! Continue reading