Simple 100% <--> 0% throttle control of a boat ESC without a big transmitter
Hello! I have a fun problem that I figure the Hobby Squawk community can answer much more expertly than my limited google search abilities.
Quick background
We are building a prototype of a powered watercraft. We purchased and tested a few different RC boats and extracted their pump jet systems, and also bought some standalone pump jet motors + pump drives. The best fit for our desired thrust and packaging was the pump jet system supplied in the Streamlinerc Thrasher V3. It's a well-designed product.
Problem
Our issue now is that we want to bypass the Tx/Rx method of sending throttle commands to the Flycolor FlyMonster 90A ESC (supplier link here and, e.g. sold separately here). The Thrasher V3 ships with a FlySky FS-GT2E gun style transmitter and pre-bound receiver. However, we will not have a way to hold and control the transmitter while also operating our prototype, and our prototype will frequently be submerged under water and thus the Rx will lose connection to the Tx.
What we need
The only thing we need is bang bang full 100% and full off throttle control. We don't need steering. We don't need partial throttle. We have the ability to toggle an on/off switch during operation. So, one would think our application is as easy at it gets!
Some incomplete thoughts on solutions
One solution that we've considered is to use a "servo tester" (e.g. here) dialed up to the full throttle signal expected by the Flycolor FlyMonster ESC. We would then toggle an on/off switch that opens or closes the 5V battery circuit supplying the servo tester. Three problems here, which I will list below. But maybe someone on this forum knows of a simple Raspberry Pi solution to our woes?
A second solution would be to find a different very small Tx + Rx pairing, preferably waterproof. Our desire here would be to package the Tx and Rx together on the watercraft, and use a toggle switch or a push-button to simply depress the throttle signal into full 100% "on" and full 0% "neutral". We could wire the Rx into the FlyMonster ESC. Maybe someone on this forum knows of a good one?
A third solution would be to replace the FlyMonster ESC with a different 50-90A ESC that we knew we could control in an easy on/off toggle method, and preferably were also waterproof. Maybe someone on this forum knows of a good one?
Thank you for any ideas here!
MHS
Quick background
We are building a prototype of a powered watercraft. We purchased and tested a few different RC boats and extracted their pump jet systems, and also bought some standalone pump jet motors + pump drives. The best fit for our desired thrust and packaging was the pump jet system supplied in the Streamlinerc Thrasher V3. It's a well-designed product.
Problem
Our issue now is that we want to bypass the Tx/Rx method of sending throttle commands to the Flycolor FlyMonster 90A ESC (supplier link here and, e.g. sold separately here). The Thrasher V3 ships with a FlySky FS-GT2E gun style transmitter and pre-bound receiver. However, we will not have a way to hold and control the transmitter while also operating our prototype, and our prototype will frequently be submerged under water and thus the Rx will lose connection to the Tx.
What we need
The only thing we need is bang bang full 100% and full off throttle control. We don't need steering. We don't need partial throttle. We have the ability to toggle an on/off switch during operation. So, one would think our application is as easy at it gets!
Some incomplete thoughts on solutions
One solution that we've considered is to use a "servo tester" (e.g. here) dialed up to the full throttle signal expected by the Flycolor FlyMonster ESC. We would then toggle an on/off switch that opens or closes the 5V battery circuit supplying the servo tester. Three problems here, which I will list below. But maybe someone on this forum knows of a simple Raspberry Pi solution to our woes?
- First, we don't know the exact throttle signal that the ESC expects. The FlyMonster user manual (link here) doesn't list it. Is it 50 Hz? 490 Hz? 500 Hz? And then what is full 100% forward throttle? Is it 10% duty cycle? 5%?
- The second problem is all of the ESC's built-in throttle signal loss protection. We expect that a suddenly disappearing and appearing throttle signal would not be recognized by the ESC.
- We have previously tested servo testers with some other ESCs and they never pair well. We have seen unreliable "jerky" throttle output from what should be a stable and constant PWM signal output from the ESC. This makes us mistrust the reliability of using a servo tester.
A second solution would be to find a different very small Tx + Rx pairing, preferably waterproof. Our desire here would be to package the Tx and Rx together on the watercraft, and use a toggle switch or a push-button to simply depress the throttle signal into full 100% "on" and full 0% "neutral". We could wire the Rx into the FlyMonster ESC. Maybe someone on this forum knows of a good one?
A third solution would be to replace the FlyMonster ESC with a different 50-90A ESC that we knew we could control in an easy on/off toggle method, and preferably were also waterproof. Maybe someone on this forum knows of a good one?
Thank you for any ideas here!
MHS