Frsky divider schematic

Post by **ShowMaster** » Mon Jul 08, 2013 5:24 pm

Before I go to the trouble, anyone have a schematic with values of the Frsky divider board?
I stopped making my own when aloft started stocking them but need one more today for a new install.
My real issue is I'm using a D8R-II and like to make A1 display something. I believe I read the 2 1ks is series will work as a voltage divider for the RX 5 v buss with the junction feeding the A1 input.
For A2 and reading a 3c lipo I believe I did yes a 10k and 2-3k at one time. I used a voltage divider pgm posted.
I'm able to work it out again but Aloft spoiled me.
I couldn't hurt to get the latest ideas for DIY dividers with the release of the Taranis attracting more new users.
SM

gohsthb · Post by **gohsthb** » Mon Jul 08, 2013 5:48 pm

Here is a formula to figure out your maximum input voltage.

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(3.3*(R1+R2)) / R2 = Vin

R1 and R2 are the resistor values. R2 is the one that goes to ground.

I have read in other posts that you don't connect the ground on the Rx side of your divider. You leave that one off because the grounds are usually connected in the BEC. Connecting it might cause a "ground loop fault" which can cause interference with the system. If you are measuring an entirely separate battery, then you will need to connect the ground wire.

What should be the minimum and maximum resistance we should use for the divider? Or another way, how much current can the analog input handle?
-Gohst

Post by **ShowMaster** » Mon Jul 08, 2013 6:37 pm

Good enough info thanks.
I do t think there is any A1 or A2 port on the x8r RX only sbus input. Frsky isn't offering any converter at this time. I understand that the vario will allow some form of interface?
Those familiar with s-buss could help out a lot with a analog to s-buss circuit that we can use right away.
I'm usually only monitoring lipo voltage and the d8r with the divider is a lightweight, small footprint option.
I can use the d8r RX's I have but I'd like to use the new x8r since I'll have one.
SM

Post by **MikeB** » Mon Jul 08, 2013 8:45 pm

To clarify to X8R connections, it has an S_BUS for driving servos, and a S-PORT for telemetry. It does not have an A1 or A2 connections externally.
FrSky are producing certain telemetry devices with S-PORT connections. These include FAS-40 (current and voltage), Vario (altitude and vario), and the LiPo voltage senso for monitoring individual lipo cells.

Mike.

Post by **ShowMaster** » Tue Jul 09, 2013 12:09 am

Thanks Mike.
I guess I'll have to use my d8r rx while waiting.

Post by **ShowMaster** » Mon Jul 15, 2013 6:20 pm

I found this divider info I had screen captured last year. I've been making and buying Frsky dividers using other configs. Good news my Taranis order shipped today, bad news is I didn't add any divider sensors in time to be included.
I need a few to use on my d8r-II recs that don't have any.
I know Mike has a favorite, and so do others. Maybe we can post them all in one place with comments on why we like them. Of course for $3 added to an order it is easier to buy it pre built for most.
How about this circuit and values?
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