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Jan 12, 2022, 11:37 AM
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Discussion

Do we still have to do this ??


Back in the late 70's when I was introduced to R/C, I was advised that when shutting off my radio system to first turn off the Rx and then the Tx. With the significant advancement in radio design is this practice still necessary OR was it really ever ??
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Jan 12, 2022, 11:49 AM
AndyKunz's Avatar
It was, and still is, good practice.

In the old days it was necessary because

a) turning off the transmitter first could cause a bad frame of data to go out, resulting in unexpected movement of your servos, possibly jamming them. If you had an electric, it could cause the motor to start unexpectedly.
b) somebody else could be on the same frequency, and they would have control of your model. You can just imagine how dangerous that could be to your servos. And if you had an electric, they would have control of your spinning meat cleaver.

With most modern systems, (b) is not a concern, but (a) still can be.

Be safe. Turn off the model before the transmitter. Please.

Andy
Jan 12, 2022, 01:56 PM
Multi-Platform Pilot
barracudahockey's Avatar
Picture this
You don't properly set your fail safe
You have an electric powered model that uses an internal bec on the ESC so you have to unplug the battery to shut off the rx
you turn off the radio before you unplug the battery
The prop goes immediately to full power.
Bad things happen to human flesh
Jan 12, 2022, 02:52 PM
TOK
TOK
Registered User
TOK's Avatar
I can't understand any advantage to shutting of your control link before the controlled device.
Jan 12, 2022, 05:23 PM
Registered User
OpenTX will keep the transmitter powered until the receiver is turned off.
Jan 12, 2022, 06:22 PM
Registered User
Thread OP
Thanks to all for your informative responses....so very glad I posed the question.
Jan 13, 2022, 03:08 AM
Registered User
as a LHS worker we always try to implant the idea of

TX on first then RX on

RX off first then TX off last

Works best that way
Jan 13, 2022, 09:31 AM
Mark LSF # 3792
Yep, what Andy said!
Jan 13, 2022, 05:39 PM
Flying a Falcon or a 3D model.
fauconnier's Avatar
Some modern transmitters doesn't allow you to turn off the Tx. first. It's still relevant.
Jan 15, 2022, 01:58 AM
Fly, Crash, Duck tape, Repeat
jdixon77's Avatar
While some modern RXs don't even fully initialize until a TX is connected, I would say yes, it should still be done. And as for, "was it really ever?", oh yes it was!

I got into RC in the 80's and had enough little rubber burns on my tummy from my little RC cars kicking into full throttle with my radio off to know the importance of this, long before I ever had brushless motors spinning hard plastic props near me :-)
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Jan 15, 2022, 01:29 PM
Youtube channel : solentlifeuk
solentlife's Avatar
Quote:
Originally Posted by Tony Hallo
OpenTX will keep the transmitter powered until the receiver is turned off.
I have latest OTX on my TX18s and I can turn off TX before Rx ..... so wondering what setup you have ..........
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Jan 15, 2022, 01:44 PM
I don't want to "Switch Now"
pmackenzie's Avatar
Quote:
Originally Posted by solentlife
I have latest OTX on my TX18s and I can turn off TX before Rx ..... so wondering what setup you have ..........
It should warn you if the receiver is telemetry capable, but you can over-ride it in case you want to test failsafe (or some other reason).
Jan 15, 2022, 03:12 PM
Youtube channel : solentlifeuk
solentlife's Avatar
Quote:
Originally Posted by pmackenzie
It should warn you if the receiver is telemetry capable, but you can over-ride it in case you want to test failsafe (or some other reason).
Warn yes ... because OTX usually has a slow shutdown unlike most other systems. But guy said OTX will not power down ....... that's a different matter.

Just checked with a model ..... (Radioking TX18S / latest OTX / FrSky Rx with Telemetry) .... and surprise - it went to a standby mode asking if I wanted to cont shutdown ... with both single button and both buttons shutdown.

Interesting.
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Jan 15, 2022, 03:22 PM
I don't want to "Switch Now"
pmackenzie's Avatar
It won't power down unless you tell it to ignore the warning.
In that sense he was correct, if not precise.

It has nothing to do with a "slow shutdown", it is an added step to prevent you from leaving a model on.

You can reduce the shutdown time to zero in the system menu, and it will shut down immediately ( but still ask if you are sure if there is a rcvr connected).

I don't have a TX18, what is a "both button" shutdown?
Jan 16, 2022, 05:04 AM
Youtube channel : solentlifeuk
solentlife's Avatar
Quote:
Originally Posted by pmackenzie
It won't power down unless you tell it to ignore the warning.
In that sense he was correct, if not precise.

It has nothing to do with a "slow shutdown", it is an added step to prevent you from leaving a model on.

You can reduce the shutdown time to zero in the system menu, and it will shut down immediately ( but still ask if you are sure if there is a rcvr connected).

I don't have a TX18, what is a "both button" shutdown?
If you read my last post - it actually shows I have found OTX latest does inhibit shutdown if RX telemetry is on ... something I was unaware off till now. Most likely because I never used Telemetry until the latest RX's I have installed. Plus of course - over 55yrs of TX on first, Rx off first .... old habits hard to lose !

Both button shutdown ? Jumper / Radiomaster / Radioking / Eachine multi protocol radios all have Two Power ON / OFF buttons. For powering ON .. its usual to just hit one button, right or left makes no difference. For powering down - you can have the slow shutdown where you press one Button ... or the near instant shutdown by pressing both buttons together. Never really understood why they have it ... but its there.
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