After spending a lot of time researching, getting help from the likes of our very own Steve_H, listening carefully to others here and other specialty sites, then re-learning my basic electronics, I now have a very stable circuit that does the following:
1) Acts as an Alternator Charging System warning - On Ignition ON, the White LED comes on, on engine start stays on until 650 RPM is reached, then goes out because the Alternator is working properly. If the light ever comes on while the engine is running, there is a Charging System malfunction.
2) Oil Pressure Warning - At Ignition ON, the Red LED stays off due to the bias placed on the relay by the Alternators Warning Circuit. At Engine on, Oil Pressure rises above 6PSI so fast the alarm never goes off and stays off. The only time you see a Red LED and hear the 95dB Piezo Alarm is with Engine Running and Oil Pressure is below 6PSI.
3) Water Temperature Warning - At Ignition ON clear through normal engine operation, you never even know you have a warning. The only time the Blue LED and 95dB Piezo goes off is when Water Temperature reaches 220 degrees. This number is fully adjustable from Ambient to 257 degrees. Since this is a circuit that you would not even know if a wire was broken to the sensor thermistor, I incorporated a Supervisor Circuit that monitors to ensure all wires are connected properly. If not, an Amber LED mounted to the box itself warns you that there is a system fault.
4) Low Fuel Warning - This circuit has one wire that hooks to the fuel sending unit and monitors the level in your tank. When the sender tells the circuit you have low fuel, the Amber LED warns you to get more fuel. This is adjustable from Empty to Half Full. This makes sense because some folks live 1 gallon away from a gas station, others live 20 miles or more away. This circuit is totally independent from the gas gauge.
Once the individual circuits were prototyped and tested, it was necessary to put them together in one larger circuit. This was all done from scratch using Proto-Breadboards and lots of small hookup wire. Its not pretty, but a necessary step. Once it was thoroughly tested using the test engine and Start Kart, I am now ready to learn how to use a new program called DipTrace. This program takes your schematic diagram and turns it into a Printed Circuit Board file. Just like Draftsight for drawing out Metal for Laser Cutting, this program configures your schematic so that the circuit is designed the most efficiently, then with PC Board Printer technology, Printed Circuit Boards are made. With the learning curve, etc, I am hoping for completed boards in about a month.
Here are a few pics:
Top side of completed prototype:
http://devestechnet.com/Images/Projects/WarningSystem/WarningSystem0070lg.jpgBoard slides into the enclosure:
http://devestechnet.com/Images/Projects/WarningSystem/WarningSystem0073lg.jpgLots more to do but the current How-to is here:
http://devestechnet.com/Home/WarningSystemIn the end, this article will explain in detail how to make this entire project yourself.
