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IVO current limiter project

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PostPosted: Mon Oct 22, 2018 2:13 pm    Post subject: IVO current limiter project Reply with quote

I've received a batch of 6 boards and assembled and tested one of them. I found that there is an error on the board. Zener diodes D5 & D9 as well as mosfet Q7 & Q8 are mixed up. Now it makes no difference at all about Q7 & Q8 as they are identical but as for labeling on the board they are mixed up, but the zener diodes D5 & D9 are different, so when assembled as per the board markings, the LED glows dimly as there is grounding current leaking through the 10volt zener diode. It still glows bright when GP1 goes high. Switching D5 & D9 corrects this issue.This can be corrected for these already built boards, by simply altering the schematic diagram, otherwise the .pcb file for the boards could be corrected. I would recommend go with the first option, as it is quite expensive to have these boards produced by expressPCB,  but they do provide along with the finished product the gerber files that will allow future boards to be produced by much less expensive sources. I'd be happy to provide these files to Bob to post with the other project files on to save costs for future builders.
   But even after correcting this issue I'm still having problems with the circuit, that I suspect are a result of my ineptitude in compiling C into hex. I've contacted Paul Fisher for his guidance on this, as he wrote the original code. The problems are surprisingly similar to one that was reported here long ago when the first iteration of this project was all hardware based without the microcontroller;
When I apply power to drive the prop motor, it will move for approx .5 second before GP1 goes high, tripping the circuit. It does this for both directions. But measured current is only a max of 6.5 amps of inrush current with about 5 amps of continuous current. The behavior of this would suggest that possibly I may have correctly compiled the code as it should trip in .5 second of high current (.5volt across R16a-d). So possibly this just needs to be changed in the code.
   After several trips up to the airport to test this, I built a bench test set-up using an electric water pump for a load as it has very similar current draw as the IVOprop motor, so that will expedite further testing. I just heard from Paul and he will take a close look at my hex code, so hopefully it will be a simple error in my hex code.
I'll update soon....
Todd Bartrim

On Tue, Sep 18, 2018 at 12:15 PM Robert L. Nuckolls, III <nuckolls.bob(at) (nuckolls.bob(at)> wrote:

At 09:29 PM 9/17/2018, you wrote:
The last 2 posts I saw on this were these 2:

Robert L. Nuckolls, III <nuckolls.bob(at) (nuckolls.bob(at)>
Fri 7/21/2017, 12:23 PM
Got the board stuffed.

I need to get my pic programmer up and running
for a couple other programs. I'll pop a 9023 chip
and see how critter works.

  Bob . . .


Paul A. Fisher <paulf(at) (paulf(at)>
Wed 10/4/2017, 11:53 AM
Bob and all,
Did we ever finish this project?  The message attached below was the last one I heard about it.  I don't know if that means it worked, that it didn't work and we gave up, or everyone just lost interest.
I don't have an IVO prop, so I don't need the limiter.  I just wondered if the software that I contributed needs any additional refinement.
Paul A. Fisher
Q-200, N17PF
RV-7A, N18PF

If there was a limiter produced I didn't see it.


  Okay guys . . . looks like I dropped the ball on this
  one. I'll hide behind the 'too many projects' phenomenon.
  Got another grand-kid living with us for a year to
  try alternatives to Wichita schools . . . etc. But
  that's not an excuse. I'll dig around and get that
  package together.

  I know Paul had sent me some POC software and I
  don't recall having loaded it into a chip. We'll
  get that pot back on a front burner today.

  Bob . . .

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 Filename:  9023-600_P3_Schematic.pdf
 Filesize:  72.57 KB
 Downloaded:  25 Time(s)


 Filename:  9023-1_BOM_and_PartsLocator_RevP1.pdf
 Filesize:  552.34 KB
 Downloaded:  24 Time(s)

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