Stand Alone Mixer Board for Use In Boats

[CraigP]

I installed a stand-alone Mixer Board into my single engine Cat to provide throttle reduction on cornering. Here is a link to the Mixer used:

https://www.banggood.com/DasMikro-RC-Signal-Mixer-For-Tank-Dual-Bidirectinal-Motor-Control-p-1162275.html?gmcCountry=US&currency=USD&createTmp=1&utm_source=googleshopping&utm_medium=cpc_ods&utm_content=heath&utm_campaign=pla-hobbies-us&gclid=EAIaIQobChMIltTr0tLu2AIVQWx-Ch1pyQEbEAYYASABEgJOEPD_BwE&cur_warehouse=CN

It must be noted that this board has an adjustment pot, with an adjustment range of 33-100%. 33% is far too high for racing and for single engine craft. I got around this by adjusting the D/R on the rudder channel down to the 35-40% then using mechanical advantage on the rudder linkage, by using a long arm on the servo and a short arm on the rudder. This forces one to turn down the D/R, or you'll hit the mechanical hard stops. The adjustment range stated for the Mixer is for 100% signal input range. So you can "cheat" this number by not using the full range from the Transmitter. I have an effective combination working on my Cat that yields a throttle reduction on rudder command of only 4%. The last time I ran it, this seemed to work pretty good. I hooked this setup into my Digital Oscilloscope and took some pics of the actual signals in the boat. This is a very inexpensive mixer solution and appears, with the correct overall boat setup, to be capable of yielding good results. NOTE: being a single motor boat, I just used on of the outputs from the mixer. This same board will work for dual motor boats as well. I will post a schematic of this device hooked into mu boat at a later date.

The first pic is Full Throttle with NO rudder. The second pic is full throttle at full rudder. The third pic is the installation. The fourth pic is NO throttle and NO rudder.

[TRUCKPULL]

Craig
In the third pic of the installation, you have a second item plugged in line with the mixer?
Is that the single motor Isolator?

Larry

[CraigP]

Yes, that's from the output of the Mixer Board, to the Input of the Single Motor Opto Board (right side). The ESC cable is then plugged into the Output of the Opto Board (left side). You can't believe the noise just coming from the internal BEC. You can see that by looking across the grounds on the Opto Board. I should take a shot of that... And realize that's not even with the motor running!

[CraigP]

Here's the full electrical schematic to my Skater 32 Cat. It includes the Mixer and the Opto Board. All components are labeled.

[TRUCKPULL]

You can't believe the noise just coming from the internal BEC. You can see that by looking across the grounds on the Opto Board!

Craig
In the past we have found that the temperature on the ESC at the radio board (this is where the internal BEC is located)
runs about 20 degrees cooler when it is not used (U-BEC)

With the Isolator we need the internal BEC to power it, is there any other way to power the Isolator?

Or any way to reduce the noise coming from the internal BEC?


Larry

[CraigP]

The BEC is virtually disconnected, it’s only providing a scant 5mA of power for the Opto Board output so it is effectively disconnected. Another big advantage to using the design. Since the internal BEC is only powering this output and it goes to the ESC, the noise is what we call common mode, meaning it has no effect within the confines of this part of the circuit.

I made a math error on calculating that percent deviation on the mixer. Since the zero mark is 1.44mS and not zero, then that moves this number to 12.8%, so I still need to whittle on it. This cat likes it where it’s at. If you don’t back off going in the corner on my Cat, it will flip. It will flip in the straights too if it hits the right wind! Cats really like going airborne! Never flipped my hydro... it gets a bit unruly, but keeps its numbers up!

[srislash]

Haha, I should put a blooper vid of airtime with my Fantasm. Yup as you get up in speed they can get light. Well I guess when the rain stops and I have time, I should try that mixer on my Daytona. I already have the long throw arm on it. Just to be different, lol.