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<p>I presume that you want to leave the gauges intact.</p>
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<p>The simplest method would be a three legged H bridge consisting of a pair of FETs per phase.</p>
<p>Then the microcontroller would cycle each phase through high, low and off in the proper order and phase offset.</p>
<p>Then you would increase and decrease the rate with the engine RPM.</p>
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<p>If that turns out to be too crude you could PWM a sine wave.</p>
<p>Then you use an opamp to buffer it, and then add a 120 degree phase shifter, second buffer, second phase shifter and third buffer.</p>
<p>If the gauge requires a lot of current you can add another amplifier to each phase's buffer..<br>
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<p>Or use three PWM outputs and let the microcontroller deal with the phase offset.</p>
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<p>Any idea on the gauges voltage and current requirements?<br>
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<div id="Signature">Vriendelijke groet,<br>
Jeroen.<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" color="#000000" face="Calibri, sans-serif"><b>From:</b> Simpits-tech <simpits-tech-bounces@simpits.org> on behalf of David C. Allen <dca911t@gmail.com><br>
<b>Sent:</b> Monday, August 7, 2017 8:04 PM<br>
<b>To:</b> Simulator Cockpit Builder's List<br>
<b>Subject:</b> [simpits-tech] N1 & N2 Gauges</font>
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<div>Hello<br>
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I was wondering if anyone has used a Arduino to get the N1 & N2 gauges operational?<br>
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>From the information I have found there is a 3 phase generator for the N1 & N2 mounted on the engine. The gauges have a 3 phase motor connected to a flux coupling (like is used in a mechanical speedometer) to drive the pointer. Once the engine is operating
the N1 & N2 are self powered.<br>
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I found a chart that lists the generator RPM vs Indicator % RPM<br>
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0 gen = 0 %RPM<br>
840 gen = 20 %RPM<br>
2520 gen = 60 %RPM<br>
4200 gen = 100 %RPM<br>
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So a question on frequency of the generator, would vary with generator RPM <br>
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Looking at one leg of the generator <br>
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0 gen = 0 Hz = 0 %RPM<br>
840 gen = 14 Hz = 20 %RPM<br>
2520 gen = 42 Hz = 60 %RPM<br>
4200 gen = 70 Hz = 100 %RPM<br>
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Just looking for ideas<br>
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David<br>
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N9070U 737-222<br>
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