Swift-Tuning Electrical Setup

Introduction

The more observant readers of the build article (and setup article) will have noticed references to the electrical system installed in the Swift-Tuning machine. This system was designed to be highly resistant to electrical interference as well as provide extended flight times. It also takes account of voltage requirements for the GY401 gyro and 9254 high-speed servo.

The system employed optically isolates the speed controller, BEC and main cyclic servos from the receiver. A separate system powered by a nimh pack powers the receiver, gyro and high-speed tail servo. This article details exactly what is included in this system and how to set it up.

Obviously this electrical setup is more expensive than your average electrical setup but it offers the best component isolation and voltage control for the components installed in the Swift-Tuning helicopter.

Components Used

• Medusa Potencia 6V 3.5A BEC
• FMA 4 channel opto-isolator
• Phoenix 60A ESC
• GY401
• S9254 high speed servo
• Hitec high torque cyclic servos
• 2000mah Nimh pack
• Standard switch harness
• JR 770 PCM rx

System Design

The design point for this system is to isolate the high voltage (6V) and noisy (interference) components from the lower voltage (5V) quiet components (Gy401, RX, s9254).

The first system is powered by the Medusa BEC at 6V. This system includes the ESC & cyclic servos. The Phoenix 60 has had its internal BEC disabled by removing the red wire from its plug. This electrical system is wired into the motor & ESC as well as the lipo and the cyclic servos. These are all the 'noisy' and high voltage capable devices.

The second system is powered by the nimh pack and includes the receiver, gyro and high-speed tail servo. The pack is connected to the switch harness allowing the receiver to be turned on and off. The switch harness also provides power via the receiver to the gyro and high-speed tail servo. This system has the quiet components consisting of the nimh, rx, gyro and s9254 tail servo.

The two systems are separated using the FMA four channel optical isolator. The optical isolator is powered by the Medusa BEC and the cyclic servos and Phoenix 60 ESC are plugged into it. The optical isolator puts a small optical path between the servos and ESC plugging in one side and the receiver plugging into the opposite side of the optical isolator.

In order to illustrate how optical isolation works beyond my description above I have included a diagram based on an illustration from the optical isolator manual.

Discussion

So what do you gain?

Firstly this system is highly resilient to interference. The Medusa BEC supplies 6V to the high torque cyclic servos giving them more speed and power. The ESC, lipo and motor are totally isolated from the receiver electrically.

The receiver, gyro and high speed servo receive 5V from the 2000mah nimh pack, which is good for many flights as it only has to power an rx, gyro and one servo. The system can also be switched on and range checked without fear of the motor spooling up. The GY401 will work fine on 6V but the S9254 won't and is 5V only, so this setup also caters for the high speed servos voltage requirements.

Unfortunately the extra BEC and opto-isolator add some extra $ to the cost of the electrical system but this is no more expensive than one good crash. My belief is that the resilience to interference in this system will make up for the initial outlay to purchase it.

Conclusion

I've been running this system for several weeks and not had any radio issues of any description. No glitching, lockouts, failsafes or in fact anything to indicate an interference issue. Not only this but I can fly all afternoon on the nimh as long as I have lipos to fuel the Swift. Responsiveness of the Swift is increased due to the 6V BEC powering the cyclic servos and I can feel safe that my gyro and high spped servo are operating at their optimum voltage. If you have glitches then I would recommend this sort of system to resolve them. Most people will be quite content with just an rx pack powering the radio system and will probably not have issues. As I said this is a slightly specialist system but it works very well and provides me with peace of mind.

Here are some pictures of the installed system.