rcpack

Hi their, I had a question about fail safes. I have been using my ofna micro fail safe for my nitro buggy for a while now and I wanted to put it in my rc10t4. I was wondering if I can use the fail safe on electric cars? Do I connect it to the speed controller or something? Will it work? Thanks.

Takedown

My Feedback: (23)

Its not needed 99% of ESC's made today have built in failsafes.

rcpack

Cool, I did not know. Thanks

DaveG55

Ummmm, what does the speed control have to do with the radio signal? And how can it tell if the signal is being interfered with?
Can you show some examples of where an esc has a built-in failsafe?
I know that several radios are coming with them now but esc's with failsafes?????
I'm prepared to be wrong but, I don't think so.

Josh222

Most speed controls will stop powering the motor if there is interference or low battery power to prevent run aways. When you get a Radio with a built in failsafe like a spectrum your supposed to disable it.

Takedown

My Feedback: (23)

^^Exactly^^ They just cut power to 0 if you go out of range or somthing odd happens.

Access

Basically the receiver sends a pulse to the ESC/servo/device every 5-50mSec. The width of that pulse determines the position of that device. Failsafe generally just means that if no pulse is detected for a set period of time, the ESC will return to the neutral position. This stops the vehicle from 'running away' if, say, it exceeds the range of the radio or if the signal otherwise drops out. The ESC doesn't really need to know why the pulses from the receiver stopped.

If you don't believe it, take the drive wheels of your car off the ground. Power up your transmitter and your car, gun the throttle and let the rear wheels spin. Then hold the transmitter at full throttle and turn it off (without moving the throttle). If your ESC has a failsafe (which just about all of them do), the rear wheels will stop spinning in short order. If your ESC did not have a failsafe, they would keep spinning since the last pulse the ESC got signified full throttle.

Try the same with steering. Turn the transmitter back on, hold the steering to one side and then shut it off. Servos don't have failsafes, the wheels will not re-center, they will stay to the side you had them on when you shut off the transmitter.

Some of the better failsafes will recognize erratic movement of the pulses and also cut that out.

Failsafe on a radio is a little different. This means the radio is actually detecting interference and either stops sending pulses or sends out nuetral position pulses when that happens. So for instance if someone is trying to hijack your signal, this would obviously help (a standard failsafe on the ESC might not). Spektrum is digital so it's probably using a CRC, parity, or some other math thing for detecting an error in the bitstream. When this error is detected, it will recognize that and send out nuetral pulses, stopping the ESC and maybe even returning all servos to the neutral position.

syncronized77

Wait....so you guys are saying that the reason why my mtroniks esc is cutting out, may not be due to overheating...but due to a crappy radio transmitter??

ASYSTEMERROR

is the setup BL or BR

DaveG55

Finally, someone explained it. I much prefer an explaination of how something works rather than a "because it does" statement. Thanks Access, I learned something today.

paintstikker

If you have ESC then it doesn't really matter as the ESC determines whether to operate based on radio signal. Though a car might "jerk" away when you turn on the car before the Rx, it won't run away like a nitro vehicle or electric with MSC because a servo jams forward.

One thing about going out of range; if you go out of range you might not know it if you are holding on the throttle; the ESC knows that before it left signal it was throttling, and the Rx still gets a glimpse of a signal. You can still control the vehicle but once you stop when out of range you can't control the vehicle much at all.