Hi Guys, Sorry I missed this post. I was in hospital for a small op. A few days ago, Yuriy Yatsenko asked me for some clarification on the gain setting, so I'll just copy what I sent to him. Yuriy enjoys using my timers, and especially for the kids he's training.
All governor systems work with a feedback loop. You can think of a motor car with a cruise control where you can set the speed to drive on a long road. The feedback loop is from the speed of the car (sensor on wheels) to the engine rpm. If you set the speed to 100 km/h and you have too much feedback gain then the speed will over-shoot 100 and then go under 100 until it settles down to keep the speed constant. In the math formula's used in good governor systems, they use the PID formula's, but it takes someone like Tim Wescott to explain this, so I'll stick to the simple explanation. This feedback loop has some gain from a factor of 1 to whatever works the best. This is the same with our model governors to keep rpm constant. More gain = faster reaction time, BUT more over-shoot or oscillation. Why my system works quite well for stunt is because I only add gain one way, or when the system is loaded like in a hard corner or climb. It all sounds good and simple but there are other factors that effect this performance, like the overall power of the motor and battery, and if the throttle setting is very close to maximum power. A governor needs what is called “head-room” to work. This means that you cannot set the throttle to maximum rpm for your flights because then you have no more throttle to use if you need it. So, we set our throttle maximum to about 85% to 90% so that we have some more throttle if we need it especially near the end of the flight when the battery has run down.
I simple way to test my system is to set the gain to 7 and try to hear if the rpm is going up and down as you fly level, especially in some wind. This is called “hunting” just like unstable model in level flight. If you hear no difference then it could be that you have set your rpm too close to maximum, or also it could be that you have a very powerful power system. If there is a lot of hunting (it is also called “oscillation”) then it is possible that you set the rpm too low. For example, my heavy Newtron 2 model with AXI 2826-10 with a 13" wood prop and 4S 3700 mAh battery makes quite a lot of variation that you can hear with a setting of 6. I changed the motor to a bigger Sunnysky 3520–880 Kv, and it makes much less variation and I can only hear a small audible difference but the model performs much better. I often set my gain to 4 for windy weather and then, using the same rpm, I wind up the gain to 6 for low wind or dead air.
I have had requests to use a negative gain for dives, but then it becomes a conventional gain system with all of the oscillation problems. It's also an open debate on just how much backing off the rpm in a dive actually brakes the descent. I believe that it it's more a function of the prop that gives a model that slowing down. Just watch and also listen to a good tuned pipe model. You don't get a drastic 2/4 break during the flight if it is setup properly. I'm not knocking the active regulation timers, like Igor's or Fioretti, but they are more complex to setup and use properly, and of course they cost more. I just try hard to keep things as simple as possible.
Thanks to John for posting his info as he knows my system very well. To add to what he replied to Motorman, the power to the timer comes from the BEC voltage regulator, but just make sure to set the output voltage to no more than 6 volts if it is programmable.
Keith R