Show Posts
Pages: [1] 2 3 ... 10
1  Using Arduino / Motors, Mechanics, and Power / Re: uno hangs on switching the relay on: November 03, 2012, 05:06:36 am
Put a diode in parallel with the coil of the big relay, right at the relay terminals, cathode to the positive side, anode to the negative side. Type 1N400x (where x = any of 1 thru 7) will do.

thanks a million that seem to solve it ..
(strange that making a pull-up to the lcd minimized at almost 100% the hangs), now i will leave it in my intensive test 500 relay actuations ..

2  Using Arduino / Motors, Mechanics, and Power / Re: uno hangs on switching the relay on: November 02, 2012, 01:19:21 pm
my first desing was with the lm2596 in 5v mode (so no need to use arduino 5v regulator) and both lcd and small relay where getting power from it..
but was even worst the hangs where more frequent.....
I can try keeping the lm2596 at 8v->arduino vin and use 3 diode in series to reduce to 5v and from that power both smal  relay and lcd...

all circuit is consuming 170mili amps so the lm2596 can give 3amps and the arduino can give this on its 5v pin, the strange is that only happen when the big relay is trigger and  (not the small that is connected to the arduino) that is coming direct from the 24v battery
As far as i know the vin uses the uno regulator the diference for the barrel is the reverse diode protection..  and i'm doing that now with 8v to the arduino

where do you suggest caps ?

btw if i don't use pull up resistors for the sca & scl i2c lines the hangs are more frequent also
3  Using Arduino / Motors, Mechanics, and Power / uno hangs on switching the relay on: November 02, 2012, 06:37:25 am
Hi im building a kind of  "ATS" automatic transfer switch  based on a battery voltage status and on the availability of 2 powersources... like

if bat < then minvolt switch to powersource 2
if bat  >maxvolt (charged) switch to powersource 1

if no powersource1 swittch to power source2
if no powersource2 swittch to power source1

* powersource1= inverter connected to the batteries 220v ac
*powersouce2= generator  220v AC

I have :
a big  dpdt (in fact 3) relay that can support 230v up to 40 amp that have a 24v coil
small 5v relay that i use to open or close the 24v circuit to the big relay...
voltage divider to sense battery voltage

Small ac/dc transformers (iphone type chargers) to sense both sources
i2c lcd that show some info on what is happening...
Lm2596 power converter to convert from 24v to 8v that go to the vin of arduino  then from arduino 5v I'm powering the small relay and the lcd.

Problem: After some switches  of the relay the Arduino hangs.... random some times after 2/3 switches some times after 50...

now if i take the lcd out it don't hang at least after 200 switches when i stopped the test  ... if i disconnect the the big relay it also don't hang...

So its the big relay(with no 230v  power presence) just by switching does any electric noise dirty that hangs the arduino  ? some times it doesn't hang but the lcd gets strange characters ...

So  do i need any decoupling capacitors , where ??? how can i troubleshoot this...

it only come back to life reseting the arduino....

Please advice..


4  Using Arduino / Sensors / Re: Voltage sensor. Isolated on: September 05, 2012, 04:23:36 pm
Hi no the link dont work and now no picture on the post
5  Using Arduino / Sensors / Re: Voltage sensor. Isolated on: September 04, 2012, 01:20:46 pm
Thanks but I'm bit lost with your diagram I will try to understand this better on the conputer.
But how does a relay and a capacitor isolate grounds ?

6  Using Arduino / Sensors / Re: Voltage sensor. Isolated on: September 04, 2012, 08:28:02 am
For now I dont want to measure. Individual cells, just all bank total  range from 23v to 30v...
7  Using Arduino / Sensors / Voltage sensor. Isolated on: September 04, 2012, 05:38:17 am
Hi Now have a voltage sensor using voltage divider , I'm measuring a solar battery bank .
This bank has a lot of amps 1000, and a lot of high amps devices inverters etc
When the inverter push by the battery arduino some times get strange USB results on the pc side  ...
So going direct I want to measure voltage without having common grounds..
At first I was thinking in 2 arduinos that communicate wireless
One measuring voltage other connected to pc ..
Then one arduino wireless connected but...
Must be a way to this cheaper and easy ..

Please give me advices ..
8  Using Arduino / General Electronics / Re: How to block AC current on: June 20, 2012, 08:06:48 am
Hi I know that It needs poweR from grid, what i want is that power that is generated don't  flow back outside of that circuit but power from the grid can flow in..

Is this possible with ac ?
9  Using Arduino / General Electronics / Re: How to block AC current on: June 19, 2012, 07:51:06 pm
is a device that you connect a powersource solarpanels or wind turbine and invert the dc power to ac synchronizing the sine wave with your existing grid suppyer ..
a good example


10  Using Arduino / General Electronics / Re: How to block AC current on: June 19, 2012, 07:28:56 pm
i want to use a grid tie inverter but i want to be sure that no power flows out of that circuit to the others...

11  Using Arduino / General Electronics / How to block AC current on: June 19, 2012, 07:17:25 pm
i mean with DC if you put diode on the positive line you prevent current to come back ...
is there any device that that do this with ac current ?

12  Using Arduino / Motors, Mechanics, and Power / optoisolated serial ttl on: June 19, 2012, 07:32:46 am
Hi have a arduino controlling my power inverter by a relay  and  every time my  the inverter is turned off or on my usb connection to arduino get lost until i unplug and plug the usb connector..
My pc is also connected to the ac part of the inverter and i thin i have here some kind of groundloop or something so i want to isolate  arduino from the pc but keeping communication with something like:

usb to serial (fdti or other) ------>optoisolator ------> arduino RX
usb to serial (fdti or other) <------optoisolator <------ arduino TX

how can i do this what kind of components do i need  ?

9600bps or 4800bps speeds are fine...

13  Using Arduino / Sensors / Re: BMS- battery management system arduino based on: June 19, 2012, 07:24:37 am
that was a way but i would need voltage dividers after the first cell and i would loose accuracy, but so far its the only way i know how to do it..


Your idea 3 confuse-me i can't understand correctly  can you please make drawing or something..

14  Using Arduino / Sensors / BMS- battery management system arduino based on: June 17, 2012, 06:21:15 pm
Hi there..
i'm here with small doubt i want to build a a small device that measures the voltage of my battery bank
i have 6 2v cells connected in series to give ~12v  (~because they can go from 1,75v to 2,45v) and thi is exactly what i want to know.
So with that the voltage i won't need any voltage divider, but my first ideia (stupid one)  was this:

but with this layout i would be adding the cells voltage and at the last one i would have 12v on arduino pin, right ?

so how do i connect all this to arduino so i can read each cell individually ?


15  Using Arduino / Motors, Mechanics, and Power / Another one bites the Dust on: February 09, 2012, 06:32:56 pm
5 Months later and another arduino gets "crazy"  switching on/off my ups grrrrrrrrrr i will have to check what went bad this time....
it seems that was the pin the the controlled the relay...
Im changing the relay with optoisolated with optocoupler 817c ...
what else can i do protect the arduino ?

Pages: [1] 2 3 ... 10