I have just created a new folder in the Files section.

In it, there are pdf files of the circuit used in my plane to connect my HKS-700E's tach signal to the GRT EIS. They include two versions of the schematic and a description of the circuit with component and assembly recommendations. The pdfs are easily viewed and printed.

The asc files can be used to simulate the circuit's operation. You can download the free Linear Technologies LTspice IV simulator from their website. It lets you run the simulation, and view the currents and voltages at any point in the circuit you choose. I really like this simulator, and think you will, too.

You can experiment with different part values to change the size of the output signal or the filter characteristics. If you do, you will find they interact, so don't be surprised! Also, this circuit is more of a pulse amplifier switching the transistor on and off, than a pure linear amplifier. As such, the transistor's characteristics become less critical. The filtering mostly controls the edge sharpness of the switching: how rapidly the voltage can move between the full on and full of switching levels.

I apologize for not unchecking the notify box and its generating several messages to the group about the files being posted.

If you are interested in this circuit, please review the files. Then, post questions or comments as you wish. You may wonder, as I do, how the electrical system works when the voltages on the wires delivering power to the rectifier and regulator module are so low. Even so, I'm quite certain I measured them correctly.

Thank you,

Don Weigt