FrSky Amp/Current Sensor.
Re: FrSky Amp/Current Sensor.
I think he might be using er9x. If so, there is no offset.
I wanted to use once a temperature sensor that reads negative values, the TMP36, and as far as I know, I couldn't because of the offset..
Had to use a TMP37 (harder to get) that only reads positive temps, also better for what I need it for.
João
I wanted to use once a temperature sensor that reads negative values, the TMP36, and as far as I know, I couldn't because of the offset..
Had to use a TMP37 (harder to get) that only reads positive temps, also better for what I need it for.
João
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Re: FrSky Amp/Current Sensor.
Thank you very much!
- MikeB
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Re: FrSky Amp/Current Sensor.
Actually, there is an offset available for the current. It works like the altitude offset, it isn't stored in the EEPROM.
In one of the fixed telemetry views, altitude is displayed. LONG MENU sets this to zero.
In another of the fixed telemetry views, both A1 and A2 are displayed. If either of these is set to 'A' (current), then LONG MENU zeroes this value.
Mike.
In one of the fixed telemetry views, altitude is displayed. LONG MENU sets this to zero.
In another of the fixed telemetry views, both A1 and A2 are displayed. If either of these is set to 'A' (current), then LONG MENU zeroes this value.
Mike.
erskyTx/er9x developer
The difficult we do immediately,
The impossible takes a little longer!
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The impossible takes a little longer!
Re: FrSky Amp/Current Sensor.
oh, didn't know about that
The little secrets our developers keep hidding from us
The little secrets our developers keep hidding from us
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Re: FrSky Amp/Current Sensor.
rainer wrote:Wouldn´t it be sufficient to specify 400 as the range of that channel with an offset of -200A
I don´t have my transmitter handy, but if it´s possible to set the range to 400 that should work.
like that 0v would equal -200A 1.60v = 0A and 3.2v=200A
Rainer
Perhaps with open9x. But for whatever reason open9x won't run properly on my TelemetreZ+th9x. I also don't mind getting dirty in the code. I was meaning to take a look anyway.
Also - Mike - Thanks again. I've been able to compile my own version and run with it. The math is a little weird - I was trying to find where you're setting the limit of 65 - any pointers? If not no biggie - I can make it work with additional hard coding. I am also going to pre-set the offset for my needs so I don't have to set it each time.
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Re: FrSky Amp/Current Sensor.
The 65 is not a set limit, it just happens.
8-bit analog value and 8-bit ratio multiplied by each other gives 65535 maximum,
This is divided by 100, and the result treated as 10th of amps, so 65.5 Amps max.
BTW, I'm about to commit an update, where I've moved several procedures to different files, where they should be. So procedures to do with telemetry are being moved to frsly.cpp. This includes scale_telem_value().
Mike.
8-bit analog value and 8-bit ratio multiplied by each other gives 65535 maximum,
This is divided by 100, and the result treated as 10th of amps, so 65.5 Amps max.
BTW, I'm about to commit an update, where I've moved several procedures to different files, where they should be. So procedures to do with telemetry are being moved to frsly.cpp. This includes scale_telem_value().
Mike.
erskyTx/er9x developer
The difficult we do immediately,
The impossible takes a little longer!
The difficult we do immediately,
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Re: FrSky Amp/Current Sensor.
Sweet. I'll check out again. Knowing the math helps a ton.
Re: FrSky Amp/Current Sensor.
Another current meter but this time 50A (but for same price you can get 100A version) and more simpler!
http://www.ebay.com/itm/390341332320
in this version it's only needed 2x1.5kohm resistor and 10uF capacitor: End result:
http://www.ebay.com/itm/390341332320
in this version it's only needed 2x1.5kohm resistor and 10uF capacitor: End result:
Re: FrSky Amp/Current Sensor.
For 100A version would the resistor and capacitor the same as the 50A?
by the way, this is really nice, small, light, simple without the digital sensor hub. especially for trouble shooting/set up new plane it is great.
by the way, this is really nice, small, light, simple without the digital sensor hub. especially for trouble shooting/set up new plane it is great.
Re: FrSky Amp/Current Sensor.
Yes, 100A only lacks resolution, output voltages are same.kaos wrote:For 100A version would the resistor and capacitor the same as the 50A?
Re: FrSky Amp/Current Sensor.
How much less resolution we are looking at between 50A and 100A?
Re: FrSky Amp/Current Sensor.
1/2
20mV/A vs 40mV/A
20mV/A vs 40mV/A
Re: FrSky Amp/Current Sensor.
Is there a way to mod the 100A version with same resolution as 50A?
I have plane/heli is running just above 50-60 amp but under 100 amp
I have plane/heli is running just above 50-60 amp but under 100 amp
Re: FrSky Amp/Current Sensor.
not in simple way, it involves opamp and subtracting 2,5V from start voltage so you don't need to divide voltage.
My suggestion: http://www.rctimer.com/index.php?gOo=go ... oodsid=861 , clean, simple and plug&play
But my opinion is if you have something that runs on 60A, +/-1A off is not big deal (by my calculation you will have resolution of 1,2A)
My suggestion: http://www.rctimer.com/index.php?gOo=go ... oodsid=861 , clean, simple and plug&play
But my opinion is if you have something that runs on 60A, +/-1A off is not big deal (by my calculation you will have resolution of 1,2A)
Re: FrSky Amp/Current Sensor.
Thank you Isvedic.
I think I am going to make the 50A version. for a couple of the planes i have may just resort to the Frysky amp sensor which cost abou the same as the RC timer version, while needing the hub. but for the model needs 100A is large enough to carry/arrange the hub too.
The greatest part of your design is simple small, easy to be used on smaller planes without a hub.
Thx again. Once I get the part, if I run into problem, I will come up here again.
Oh, what happens if I use the 50A on a plane that may have a burst of 55-60 A in the rare extreme situation, the sensor just burn out and just won't read the amp any more or if burns out it will cut off the power as well?
I think I am going to make the 50A version. for a couple of the planes i have may just resort to the Frysky amp sensor which cost abou the same as the RC timer version, while needing the hub. but for the model needs 100A is large enough to carry/arrange the hub too.
The greatest part of your design is simple small, easy to be used on smaller planes without a hub.
Thx again. Once I get the part, if I run into problem, I will come up here again.
Oh, what happens if I use the 50A on a plane that may have a burst of 55-60 A in the rare extreme situation, the sensor just burn out and just won't read the amp any more or if burns out it will cut off the power as well?
Re: FrSky Amp/Current Sensor.
"The thickness of the copper conductor allows survival of the device at up to 5x over-current conditions." So you won't go down because of that, but if you get reading of 60A from 50A sensor let me know I'm curious too
Re: FrSky Amp/Current Sensor.
who wants to be the 1st tester on that?
I think I will be the 1st, my heli uses 45A esc and some times they got really hot, I suspect it some times goes to 60A bursts and it will puff a 2200mah 20C lipo.
order the ebay chip now. one spare for tester.
I think I will be the 1st, my heli uses 45A esc and some times they got really hot, I suspect it some times goes to 60A bursts and it will puff a 2200mah 20C lipo.
order the ebay chip now. one spare for tester.
Re: FrSky Amp/Current Sensor.
from their docs:"When the current flowing through the copper conduction path (between the IP+ and IP- pins) exceeds this threshold, the open drain overcurrent fault pin will transition to a logic low state"
So in theory over 50A it should show 0A
So in theory over 50A it should show 0A
Re: FrSky Amp/Current Sensor.
Great, thx for the info, at least I don't need to worry about crashing the plane.
by the way, can't order the chip yet (pay now). It is Chinese New Year, it does not matter order it today or a wk from now, nobody is going to process/ship it till a wk later.
by the way, can't order the chip yet (pay now). It is Chinese New Year, it does not matter order it today or a wk from now, nobody is going to process/ship it till a wk later.
Re: FrSky Amp/Current Sensor.
The seller doesn't sell to Germany..
Will this one work? I think this one is unidirectional with 60mV resolution
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... ink:top:en
Thanks
João
Will this one work? I think this one is unidirectional with 60mV resolution
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... ink:top:en
Thanks
João
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Re: FrSky Amp/Current Sensor.
It should, just be careful in what direction you put current.jhsa wrote:The seller doesn't sell to Germany..
Will this one work? I think this one is unidirectional with 60mV resolution
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... ink:top:en
Thanks
João
Unidirectional have 50% better resolution (60mV/A vs 40mV), end voltage is higher than bidirectional but still lower than 3.3v after 1:2 voltage divider
Re: FrSky Amp/Current Sensor.
But I think that with the biderectional sensor you would have to set an offset on the radio as the zero amps would not be equal to zero volts on the output, right?
Also why a divider? If you look at the specs on the ebay page, it says that output is 2.5V. I don't know how they calculate that as 0.06V (60mV) X 50 = 3V, not 2,5V
Or maybe I'm missing something..
João
Also why a divider? If you look at the specs on the ebay page, it says that output is 2.5V. I don't know how they calculate that as 0.06V (60mV) X 50 = 3V, not 2,5V
Or maybe I'm missing something..
João
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Re: FrSky Amp/Current Sensor.
UPDATED!
still over frsky 3.3v A1/2 input limit
Right, offset is 0.6Vjhsa wrote:But I think that with the biderectional sensor you would have to set an offset on the radio as the zero amps would not be equal to zero volts on the output, right?
when is 0A output is 0.6V and on 50A is 0.6V+3V(60mV x 50)=3.6Vjhsa wrote:Also why a divider? If you look at the specs on the ebay page, it says that output is 2.5V. I don't know how they calculate that as 0.06V (60mV) X 50 = 3V, not 2,5V
Or maybe I'm missing something..
João
still over frsky 3.3v A1/2 input limit
Last edited by isvedic on Tue Feb 12, 2013 12:19 pm, edited 1 time in total.
Re: FrSky Amp/Current Sensor.
But because this one is unidirectional I thought it would be 0V at 0Amps....
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Re: FrSky Amp/Current Sensor.
but with unidirectional 100A you can measure 65A with no voltage divider and still preserve good resolution!
offset=0.6V and resoulution=40mV/A
so 0.6V+(40mV/A x 65A) 2.6V = 3.2V <-- bingo!
offset=0.6V and resoulution=40mV/A
so 0.6V+(40mV/A x 65A) 2.6V = 3.2V <-- bingo!
Re: FrSky Amp/Current Sensor.
so, with the 100A sensor and not exceeding 65A We get the best possible resolution, right?
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Re: FrSky Amp/Current Sensor.
Yes, resolution in that case would be 0.3A
Re: FrSky Amp/Current Sensor.
Is there a link for the unidirectional 100A sensor?
Thanks
João
Thanks
João
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Re: FrSky Amp/Current Sensor.
sounds like I should get a 100A chip too. glad did not order it yesterday. 65A would cover most of my needs.