Friday, February 26, 2021

Warning Indicators

The Short Story

I'm going to go with the Summit Technologies HAWK Array rather than rolling my own. It's less expensive and would look better than what I would build for my own usage.

The Less Short Story

For the purpose of testing my car's electrics I built a prototype indicator array. It half worked. I sunk all of the LED cathodes to a common chassis ground because I made bad assumptions. 

What indicators sink to what, briefly.

  • Discrete Source, Common Sink
    • Right Turn
    • Left Turn
    • High Beam
  • Common Source, Discrete Sink
    • Oil Pressure
    • Alternator
    • Brake

分りません!

Reading it that way is a little confusing if you've not fully grasped that some things within the car are ground switched. I had the boys down in R&D whip up this janky diagram to help better illustrate the point. (Brown lines are ground/sinks)

How does the HAWK Array work in this configuration?

The HAWK indicator array is already wired up with exactly these indicators lamps with exactly this configuration of sources and sinks. It's like it was purpose built for British kit cars. (It was purpose built for British kit cars.)

What the other stuff about bulbs, watts, and field exciter circuits?

Depending, I may need to build a circuit that will excite the alternator so that it'll produce power at idle. It's a fairly simple circuit, especially if you're using an incandescent bulb. If you're using an LED, well, they offer little forward resistance so they might not excite the alternator and you need to bridge a resistor that will simulate the load of a 2-4 watt bulb. (@12V)  I might need to do this with the HAWK array, but I'm not 100% sure on that right now.

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