ESC's and 2.4GHz radios

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ESC's and 2.4GHz radios

New postby retiredVTT on Mon Oct 26, 2009 3:59 pm

I came upon this year old post from Lucien Miller, distributor for Scorpion procucts, and thought it might be helpfull to post it here, as from time time I hear things at the field related to unsolved mysterys involving the 2.4Ghz radios.
Sometimes a "bind" is lost between the Tx and Rx ...or sometimes the Esc does not "arm" itself the first time around.

These systems are quite sophistacated and we tend to take them for granted.
Have a read about this "No receiver signal present" starts in paragragh two...
Yes, this info pertains to the Scorpion line of ESC's and I have no info on whether other brands of ESC's use similar setups...


..from Lucien Miller of Scorpion products,

"There was an issue with the ESC instructions that caused a few problems. On some of the ESC's that shipped out from the factory, the programming instructions had a mis-print. SW1 on the dip switches needs to be in the On position to select the user mode, and in the Off position to get the factory default mode. Some of the instruction sheets have this reversed, and it has caused some confusion.

The continuous "Dee-Doo" sound can mean 1 of 2 different things. It can be an over voltage indication, but it can also be a "No receiver signal present" warning. If you plug in the speed controller, and forget to have the ESC plugged into the receiver, 5 seconds after you apply battery power the ESC will give out the continuous warning tone.

This is a safety feature that has been built into the ESC, that warns you if you power up the ESC, and it has no signal from the receiver. This was done to prevent a run-away condition in the pits in case someone was running a system with a seperate receiver battery, and forgot to turn on the power to the receiver before they plugged in the motor battery.

When you are using the built-in BEC to power the receiver and servos, the receiver gets powered up at the same time as the ESC does. With a conventional radio and receiver, the receiver starts sending out throttle signal to the ESC in less than a second after being powered up, usually in less than 1/10th of a second.

The problem has come up with the newer 2.4GHz radios. The receiver is basically a microcomputer that has to "Boot up" like a mini computer, and this normally takes 2-3 seconds before it starts sending out controll pulses to the speed controller. For some reason, some of these receivers do not "wake up" very fast, and can take 5-6 seconds, and sometimes even 8-10 seconds to completely boot up. When the speed control is mixed with one of these receivers, the 5 second window for getting a good pulse times out before the receiver starts sending out control pulses, and the speed controller shuts down and goes into the warning mode.

You did not say how long after you plugged in your battery that the "Dee-Doo" sounds started, but I would bet that it is around 5-6 seconds after you plug in the battery. What happens is that if you unplug the battery and plug it back in, next time it might only take 4 seconds for the receiver to boot up, and if this happens, the ESC is fine and runs properly.

In your particular case, I do not think that it is a matter of the battery voltage running down in an over voltage condition, it is the receiver waking up too slowly. You did not say which radio and receiver you are using, but I would imagine that it is a Spektrum DX7 with the AR6100 receiver. This is the one that seems to be causing the most problems right now.

I am not 100% sure of the exact cause, but I think that it has something to do with other 2.4 GHz radios being on at the same time. If the radio sees another similar radio running on the same frequency, it has to hop around to find an unused channel, and this extra time is what is causing the problems with the slower boot up of the receiver.

I have a Spektrum DX6 and DX7 radio with an AR6000 and AR6100 receiver. I cannot get either one to fail here, so I cannot isolate the problem. I will continue testing and see if I can come up with anything."

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