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Display Lightspeed Ignition Advance on G3X?

NovaBandit

Well Known Member
The Lightspeed Plasma III's have the ability to display the current ignition advance on a external screen that Lightspeed sells. The format that is output is .01 volts per degree of advance. Is there a way to feed this into a G3X (touch) and have it display on the engine page?

If it's not possible to directly wire that output into the G3X, are there any intermediate boxes that could convert that signal into something the G3X can use?
 
I can't see any reason the you could not use the second set of fuel level inputs. The only issue is whether the G3x allows you to change the label from aux fuel 1 and 2, to timing. You would have to determine a voltage to timing degrees relationship, then create a simple voltage divider with a potentiometer and using a DVM calibrate the fuel level to correspond to the timing advance. You can designate color bands etc. for the display.
 
I have found that you can not connect the timing/advance signal from an LSE Plasma(I) directly to the GEA24 analog input pin. It looks like the GEA24 input has too much impedance for the LSE output.

I was able to get this to work by buffering the signal with an LM324 op-amp configured as a voltage follower and powered from the GEA24 +5V pin.

I have the Plasma(I) and I don't know if the Plasma(II/III) would have the same issue.
 
...I was able to get this to work by buffering the signal with an LM324 op-amp configured as a voltage follower and powered from the GEA24 +5V pin.

I have the Plasma(I) and I don't know if the Plasma(II/III) would have the same issue.

I recently connected my Plasma II to my new Touch and have the same issue. The Plasma outputs just as the spec says as measured by my high impedance Fluke meter... But when connected to in my case the GSU73, the display shows about 10 deg low.

Searched and found this from a TI spec sheet:

LM124%2520Voltage%2520Follower.JPG


Looks easy enough to implement.

Thanks for the tip!

Heinrich
 
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27y5ufb.jpg


1) The LM324 has four op-amps and we only need/use one.
2) The two 10k resistors keep the three unused op-amps in a quiet, low power state.
3) You can usually get the LM324 at Radio Shack.
4) There is a single amp, 5 pin package version (LM321) but it is harder to find.
5) The current draw on the GEA24 +5v pin is slightly less than 2ma.
 
The Lightspeed Plasma III's have the ability to display the current ignition advance on a external screen that Lightspeed sells. The format that is output is .01 volts per degree of advance. Is there a way to feed this into a G3X (touch) and have it display on the engine page?

If it's not possible to directly wire that output into the G3X, are there any intermediate boxes that could convert that signal into something the G3X can use?

Hello Ed,

The GEA 24 general purpose inputs that are available for customized use in this manner have a minimum input impedance of 34K ohms, so we are surprised that the signal from the ignition module wouldn't drive this input, but others seem to have confirmed this is the case. We will do some tests with a Plasma III and report back. Update: LSE has confirmed that the timing advance signal provided by these ignition modules will only work when the input impedance is at least 1 Meg ohm, so the 34K ohm input impedance of the GEA 24 is too low for this signal.

Meanwhile, here are some example screens to show how you can custom configure and calibrate (simple two point line) an electronic ignition timing advance gauge with a response of 0.01V/deg.

You can create a custom name, configure color bands, and even add a tick mark per your personal preference.

ADVDegSetup.png


AdvDegCalibrate.png


Thanks,
Steve
 
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If you don't like soldering, a slightly lower parts count solution would use something like an MCP601, single op amp in an 8-pin package. It's only simpler because you don't have to worry about quieting down the unused amps in a 4-amp package. Fewer parts to deal with. The part is readily available -- Digikey or Mouser, along with several other suppliers I imagine.
exemplar.png
 
The GEA 24 general purpose inputs that are available for customized use in this manner have a minimum input impedance of 34K ohms

Buried in the Plasma(I) manual is the note ".01 v/deg into 10Mohm" which is a rolleye number but I guess that would do it. I did not find any mention of impedance in the Plasma(II/III) manual.
 
I dare someone to call up Dr. Jekyll and Mr. Hyde and tell him his output driver needs to be improved... :p :eek::eek::eek::eek::eek::eek::eek:

Just kidding...Just kidding...
 
GSU 73?

Will this work with the GSU73 as well? I'll dig into the wiring diagrams tomorrow when I'm at the hangar, but it would be a nice addition. Certainly for $0.58 and a bit of wire it is worth it.
 
Will this work with the GSU73 as well? I'll dig into the wiring diagrams tomorrow when I'm at the hangar, but it would be a nice addition. Certainly for $0.58 and a bit of wire it is worth it.

Hello Kevin,

Yes, this type of custom gauge support was recently added for both GSU73 and GEA24 engine interfaces used in both G3X and G3X Touch systems.

Thanks,
Steve
 
Thanks!

Hello Kevin,

Yes, this type of custom gauge support was recently added for both GSU73 and GEA24 engine interfaces used in both G3X and G3X Touch systems.

Thanks,
Steve

Excellent, thank you. I'll add this to my wiring tasks and order up an op-amp from DigiKey.

I did notice that it took just a few minutes over an hour for Garmin support to answer this question. You guys are slipping... :p

Thanks for the awesome support.
 
Just another data point for this thread, we wired an Electro Air E.I. advance signal into a G3X Touch as Steve suggested in post #6 of this thread. Worked out very well. Ran the engine yesterday on the RV-8 for the first time and noted that the advance gauge that we set up was indicating close to the advance curve values. Very stable. Nice feature.
 
Timing advance on EFIS

In response to Ed’s first post I have an Electroair ignition system on the right side in place of the mag. The spark signal output wire is connected to a Flight Data Systems L2E ignition adapter I installed (http://www.fdatasystems.com/l2e-light-speed-to-efis-adapter). From there it connects directly to the engine portion of my AFS EFIS. Granted it’s an AFS EFIS and not a Garmin but don’t see why it wouldn’t work. The folks at AFS, Flight Data Systems and Electroair guided me through the installation process and it worked the first time I cranked the engine after the upgrade.

The spark advance output format for the Electroair ignition is .01 volts per degree of advance just like the Lightspeed system you discussed. I was not able to connect the spark advance directly to the EFIS but by using the L2E this allows the EFIS to see a value it can then present on the display. I had an old LCD display that was pretty darn accurate when it worked but it was beginning to flicker and become unusable, hence the upgrade. Like Peyton said, you will have to configure the EFIS for an available aux input to display on your Garmin EFIS. Might be worth a call to Flight Data Systems to discuss your application-
(831) 325-3131
 
If you don't like soldering, a slightly lower parts count solution would use something like an MCP601, single op amp in an 8-pin package. It's only simpler because you don't have to worry about quieting down the unused amps in a 4-amp package. Fewer parts to deal with. The part is readily available -- Digikey or Mouser, along with several other suppliers I imagine.
exemplar.png

The MCP601 is an awesome part. The LM324 or 358 parts won’t work in this application because the output cannot swing all the way to the bottom rail. Also, with two resistors, you can increase the gain by 10X (100mV per degree), making the signal easier to process.

V
 
The MCP601 is an awesome part. The LM324 or 358 parts won’t work in this application because the output cannot swing all the way to the bottom rail. Also, with two resistors, you can increase the gain by 10X (100mV per degree), making the signal easier to process.

V

Vern,

Can you expand on this regarding the resistors? Where would they be in this diagram, and would it change the parameters for calibrating the EFIS?
 
You can set the amount of gain you want in the circuit using two resistors, as Vern mentioned. The circuit I posted is for a "unity gain" implementation, where voltage out = voltage in. If you want, for example, a 10:1 gain where 1 mV in results in 10mV out, you would use a couple of resistors in the feedback loop like this:

https://www.electronics-tutorials.ws/opamp/opamp_3.html

with-gain-e1599236310923.png


Resistor selection could be something like 10K for R1 and 9K Ohms for R2. I'm sure Vern is more familiar with op-amps in gain configurations like this, and might have better suggestions for resistor values. The vast majority of my work is more in the digital domain; I resort to analog when necessary but it's usually just reading ADC inputs or generating PWM outputs.
 
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