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I am currently working on a project and to that end, i need to switch a 50VAC, 6-7 micro amp input across two outputs with a delay.I used a relay module connected to an arduino to do so. I intended for the current to flow from the COM of the relay to the NC for one second, then cut off, and switch over to the NO for another second (looped). I expected have a 50VAC in both of my outputs for one second each.However upon measuring the output, the voltage from the NC is only about 30VAC whilst the voltage at NO is 10VAC. Does anyone know why this is happening and how to correct it? I tried using a different relay module with similar specs but the problem persists

The specs of the relay module and the datasheet can be found here:

Datasheet:http://image.dfrobot.com/image/data/DFR0017/DFR-0017-Relay%20JQC-3FF.pdf

Specs:https://www.dfrobot.com/wiki/index.php/Relay_Module_(Arduino_Compatible)_(SKU:_DFR0017)

My Arduino code:

void setup()
{
  pinMode(7, OUTPUT);     
}

void loop()
{
  digitalWrite(7, HIGH);   
  delay(1000);                  
  digitalWrite(7, LOW);    
  delay(1000);                  
}

I greatly appreciate all and any help regarding this issue:) layout of relay

the input is from a wave generator and my outputs are connected to an oscilloscope

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  • 2
    \$\begingroup\$ Could you provide us with your schematic too? \$\endgroup\$ – MCG Mar 27 '18 at 8:19
  • \$\begingroup\$ Is the current you are switching really .05mA? Please confirm. \$\endgroup\$ – AlmostDone Mar 27 '18 at 8:21
  • \$\begingroup\$ i checked with a multimeter and its about 6-7 micro amps \$\endgroup\$ – Gughan T S Mar 27 '18 at 8:41
  • \$\begingroup\$ 0.05mA is 50uA.... 5uA is 0.005mA \$\endgroup\$ – MCG Mar 27 '18 at 8:48
  • \$\begingroup\$ its 6-7 micro amps. i might have read the multimeter reading wrong previously.sorry \$\endgroup\$ – Gughan T S Mar 27 '18 at 8:50
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The relay appears to be a standard SPDT switch It would be useful to see a schematic Its contact resistance should be negligible at this sort of current Does it "click" at one second intervals? What is the waveform on the coil? It should be a square wave with a 2 second cycle - presumably driven by pin 7 of the Arduino
I take it the Arduino can drive the relay coil direct - you may need to use a transistor to do this if not. Make sure you have suitable back EMF protection (eg a reverse diode) across the coil. You could try measuring the resistance across the contacts on each path as the relay switches - it should be close to zero I am puzzled about the 50VAC at 50uA - if the source limits the current to the load then the voltage across the load will be reduced. Why 50V and 50uA? What frequency AC? As I said a schematic and some details of the application should help

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