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Hello Guys,

I have put this post together to explain the Motorised Throttle Unit (MTU) for those who do not know the back story and to help explain why it's one of my best design products but probably the worst documented and why the build videos suddenly stopped.

We were still in Brunei this time last year, enjoying the sun and sea. The MTU build was going well, and the MTU was due to be released around May. Suddenly, I had to rush to get the MTU out overnight. This was because several people in China and Japan stole the plans. They had signed onto my Patreon, where I share my designs for those guys to test. Some entrepreneurial people put the build into mass production. It was at this point I started to receive requests from people about repairs on the products they had received. I have never laughed so much, as you could clearly see 737DIYSIM all over the products.

Suddenly, my designs were out and being mass-produced and sold before I had even created the build and parts guides. This left me with no option but to release the MTU without finishing the guides and videos. Although I had fully finished my unit and at least 7 Patreons who had all successfully built their units, producing the guides take forever!

Then our contract suddenly ended in Brunei, and we had to return to the UK....Looking back, this pretty much was the end of the dual-seat 737 sim. I still have the throttle unit and use it daily, even for my Cessna flights. It was also displayed at the flight sim expo.

After hundreds of hours and over a full year in design and prototyping and moving back to the UK, returning to the massive MTU project has been tough.

Once the 737SS MIP is finished, I will revisit the MTU and finally complete the build videos along with a few modifications from my Patreons.

This week I have had hundreds of questions regarding the MTU, and all are very similar:

1) Can you build the MTU without motorising it?

Absolutely! This is a solid build and a much better design than version 3. It was designed from the ground up and uses hall sensors or pots for the axes. With a Leobodnar card or Arduino micro pro, this can be used as a standard throttle unit joystick.

Add the two cheap steppers if you want an exceptional feel of the throttle levers. Do not electrically connect them. They are there for friction and resistance.

2) The build guide says Prosim is the controlling software. Can PMDG or XP be used?

In theory, yes, many people have said they have achieved this. But I am yet to see a person give that information out for others to follow.

3) Where is the build guide?

You need to start at build guide 1, not build guide 5. There are so many steps that they couldn't fit into a single build guide. All 5 build guides need to be consulted. They all can be found here:

4) Where is the Wiring Diagram?

This is located in build guide 5. There are actually two build diagrams. A close-up of a single motor connection and a complete full wiring diagram. They both can be found here:

5) How do you programme the MTU if I have Prosim?

This is now much simpler. Download the Mobfilight MCC file:

Download ZIP • 2KB

Open it, then connect your devices to the config page. All the line entries have already been completed.

I hope this helps answer some of the many repeat questions I receive almost daily. It's a fantastic build, and I hope to progress this much further. Kind Regards, Karl.

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Mar 01, 2023


This mcc file only works with Prosim, or I can only use it with Mobiflight


Would someone be willing or able to cut the mtu base into 2 parts with a way to glue it together so I can print it on the size printer I have?

Replying to

How high can you print? I've sliced it into 4 quarters for my brothers smaller printer.

I'd be happy to slice into 8 and add supports for glue or bolts for you. With karls permission obviously.


Do the stepper motors need 24v or can they run on 12v?

Replying to

I bought a 24-volt supply and installed it. I didn't notice much of a difference. The 24-volt supply works fine and was inexpensive.


Steve Lilley
Steve Lilley
Feb 23, 2023

Good morning Karl, or across the pond that would be good afternoon. I got the plans from you a year ago and finally getting it built... too many irons in the fire. It is all printed and in assembly mode. This is one of the most fun projects I have worked on... was a remarkable piece of 3D engineering. I will be using this on X-plane using Teensyduino on a Teensy 4.0. I am going to write a couple of programs, one for X-plane and one the testing the MTU. I will send them to you so you can share them with the sim builders. I also plan to create a PCB for the MTU and using DRV8825 plug-in drivers…


Thanks for the explanation and updates Karl, all parts printed and ready to put together, just need to finish off the FMC first! I blew all the led's in the switches with an incorrect power supply so these all need replacing - proper hand on face moment! But can't wait to get it all put together and working - hopefully with PMDG fingers crossed.

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