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Matt Dralle's RV-8 Project
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Date: 1-27-2009
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Number of Hours: 2.00
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Manual Reference:
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Brief Description: VP-200 Annc. Logic Reversing Circuit - Part 1
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The starter relay has an output pin - generally labeled "I" - that is turned on when the relay is engaged, i.e. the starter is on. The idea behind this output is that you would wire it to a light bulb on the dash and then to ground. Whenever the starter is engaged, the light will come on and warn you that the starter is currently on. Otherwise, if the relay were to become stuck you probably are not going to be able to hear it and likely damage the starter and probably the engine.
The VP-200 LCD display has the capability of configuring "Annunciator Lights" for most any condition you might want to warn yourself about. There are 16 input pins on the VP-200 system that allow you to connect a switch to ground and trigger the input. Using the Annunciator Configuration page on the VP-200, you can configure when the warning is displayed, what pin on the CU or DU that it is coming in on, and what the warning says.
All of that sounds like a perfect setup for the aforementioned Starter Warning. The problem is that the output on the starter relay is 12v when its on, and the VP-200 inputs expect to see GROUND when activated. So, I came up with a little logic reversing circuit that converts the 12v output from the starter relay to a connection to Ground. It uses a standard NPN small signal transistor, a couple of specific-value resistors, a small bit of project board from Radio Shack, and some heat shrink tubing.
See that attached schematic diagram along with the pictures showing the project board implementation, connection to the VP-200 Keep Alive +12v supply as well as its I/O #8 pin on the CU. Also shown in the pictures is the Annunciator Configuration screen for the specific "Starter ON" warning, and finally the main VP-200 display with the starter engaged and the warning Annunciator activated.
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Copyright © 2008-2024 Matt Dralle. All Rights Reserved.
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