Newbie Question before I apply power - RC Groups
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Nov 09, 2017, 10:00 AM
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Newbie Question before I apply power


I have flown some cheapo drones so I have some pilot skills (left a couple in trees ). Lately I have been building a drone. All along I have been testing as I build. I am at a point where I am a little mystified. The last piece to power up is the X8R receiver. The pinouts are a little unclear. I am not sure where power input is. I wired power to the RSSI + and - pins. The manual makes no mention of where power should be applied. Can I apply it to any of the 3 ports with a + and - ?
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Nov 09, 2017, 10:06 AM
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That does not sound right! I don't have X8R receiver but you do not want to put power on RSSI pins. RSSI is the receiver's signal strength output. Get the manual for that RX and it will show you how to hook it up. Usually there are three pins - SBUS, + and - in a row.

Do NOT power it up until you have this correct. Build a "Smoke Stopper" to do your first power up. Search the forum for it. It is a 12V car tail light bulb in series with the power connector that limits the current if you have a short or miswire. It can save you $$.
Nov 09, 2017, 10:18 AM
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Ace12GA's Avatar
That Rx flags 3 connections, for SBUS, RSI, and SmartPort. Or 8 for conventional PWM. You should be able to use the +/- pins to supply 5 volts to the Rx at any connector where they are explicitly indicated.

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You should probably refer to the manual for the Rx too.

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Nov 09, 2017, 10:25 AM
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It's a bit confusing but you want to use the three pins labeled SBUS Port. See the left hand picture in the RX manual posted above. You can use a servo cable to connect to those three pins. Make sure you don't get the polarity wrong and you will be good to go. Do use a Smoke Stopper.
Nov 09, 2017, 10:48 AM
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Thank you Volt Ampere


The manual is clear as mud and makes no mention at all of where to apply power or what the pins labelled +,-, and 5 do?? What I was wondering was although there are 3 sets of pins labelled + and - nowhere does it say whether they are input or regulated output. I read somewhere that someone said the three sets of + and - are connected in parallel. I take it that on RSSI and SBUS the other pin is serial data and on the +,- and 5 the 5 pin is 5V regulated. Does this sound correct?

One more question what is a smoke stopper? Is it a polyfuse? There is a circuit I use in my electronic designs that uses a polyfuse and transorb. It protects against overvoltage and excessive current.
Last edited by exponent; Nov 09, 2017 at 10:53 AM. Reason: more info needed
Nov 09, 2017, 11:49 AM
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Quote:
Originally Posted by exponent
The manual is clear as mud and makes no mention at all of where to apply power or what the pins labelled +,-, and 5 do?? What I was wondering was although there are 3 sets of pins labelled + and - nowhere does it say whether they are input or regulated output. I read somewhere that someone said the three sets of + and - are connected in parallel. I take it that on RSSI and SBUS the other pin is serial data and on the +,- and 5 the 5 pin is 5V regulated. Does this sound correct?

One more question what is a smoke stopper? Is it a polyfuse? There is a circuit I use in my electronic designs that uses a polyfuse and transorb. It protects against overvoltage and excessive current.
Ya, it's confusing at times. The "5" is actually an "S" for Smart Port. You can update the firmware on the receiver using that port. In order to update it, you'd have to power it, so they conveniently provide + and - alongside the SmartPort pin.

As mentioned already, if you're using S.Bus, then just use the + and - and S.Bus pins for power, ground, and signal to the FC respectively. If you're using PWM then the giant grid of pins is what you'll be using. The middle column is power, with signal and ground flanking it respectively. When in doubt, JC (RIP) to the rescue...

https://youtu.be/RH_RuVbF2YU?t=46
Last edited by day o; Nov 09, 2017 at 12:00 PM.
Nov 09, 2017, 12:46 PM
Registered User
If you search this forum for "Smoke Stopper", you will find pictures and info. It is a 12V car tail light bulb wired in series with a male and female XT60 (or whatever you are using) connector. It puts that bulb in series with the battery to limit the current in case of a short.


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