If you want to run SBUS on older flight controllers and your RX only outputs an inverted signal you will need a way to invert that signal again before plugging into the FC. An inverter cable is a simple and cheap thing to make, and here's a little guide on how to do it.
This is the basic schematic:
![[Image: b3883d9282a41f9961ad90f317e3b1fd2562e817.png]](http://www.dronetrest.com/uploads/db5290/original/2X/b/b3883d9282a41f9961ad90f317e3b1fd2562e817.png)
R1 -- 6.8k Ohm Resistor
http://www.petervis.com/electronics/Stan...s/6K8.html
R2 -- 2.2k Ohm Resistor
http://www.petervis.com/electronics/Stan...s/2K2.html
Q1 -- BC337 Transistor
http://bit.ly/1nmR5Jt
Some additional reading on transistors might be helpful. This is a pretty good primer: http://www.technologystudent.com/elec1/transis1.htm
The positive lead just goes straight through. Ground is also straight though; however, the transistor emitter leg and R2 are "t-tapped" form the ground wire. The input signal connects to R1. R1 then connects to R2 and the base leg of the transistor. The collector leg of the transistor then goes to the output signal.
When the input signal has voltage (is sending an "on" bit) the transistor switches "on" and the output signal connects to ground making the output signal "off". When the input signal does not send voltage (is sending an "off" bit) the transistor switches "off" and the properties of the transistor mean that some voltage will still emit from the base to the emitter leg and therefore the the output signal is "on". It's literally inverting the signal from 1,0,1,0 to 0,1,0,1... for example.
R2 is there to ensure what when the signal input is "on" most of that voltage goes to the transistor and turns the transistor on. If it weren't there the transistor would always stay off.
I am not an EE, so there I can not go into much more depth here, but I have successfully made one of these cables so I thought it might be helpful for someone else in the future.
This is the basic schematic:
R1 -- 6.8k Ohm Resistor
http://www.petervis.com/electronics/Stan...s/6K8.html
R2 -- 2.2k Ohm Resistor
http://www.petervis.com/electronics/Stan...s/2K2.html
Q1 -- BC337 Transistor
http://bit.ly/1nmR5Jt
Some additional reading on transistors might be helpful. This is a pretty good primer: http://www.technologystudent.com/elec1/transis1.htm
The positive lead just goes straight through. Ground is also straight though; however, the transistor emitter leg and R2 are "t-tapped" form the ground wire. The input signal connects to R1. R1 then connects to R2 and the base leg of the transistor. The collector leg of the transistor then goes to the output signal.
When the input signal has voltage (is sending an "on" bit) the transistor switches "on" and the output signal connects to ground making the output signal "off". When the input signal does not send voltage (is sending an "off" bit) the transistor switches "off" and the properties of the transistor mean that some voltage will still emit from the base to the emitter leg and therefore the the output signal is "on". It's literally inverting the signal from 1,0,1,0 to 0,1,0,1... for example.
R2 is there to ensure what when the signal input is "on" most of that voltage goes to the transistor and turns the transistor on. If it weren't there the transistor would always stay off.
I am not an EE, so there I can not go into much more depth here, but I have successfully made one of these cables so I thought it might be helpful for someone else in the future.
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