What special quality of this voltage are you sensing?
Is there some accuracy spec or any other parameters you can share about your secret project?
i am sorry 230v not 220. I am using a rectifying bridge to convert the Ac to Dc (since i havent found an opto coupler which takes direct ac input) and the i read somewhere that the DC output is ~.070 AC. Is that right?Just curious, 200VAC/50 Hz is an unusual combination. 220/230/240, have seen that. What is the source of the 200 VAC?
If I may make a suggestion, put as little on the 200 volt side as possible. For example, if you get away with moving the capacitor to the output of the optocoupler you can use a lower voltage (and safer) capacitor.
Something like this:
The diode across the LED might have to be external if your coupler doesn't already have it. It can be something small like a 1N914. You might want to make the collector resistor larger and put a capacitor across the collector/emitter so that get steady voltage present/not present signal.
I use an old ac-output wall-wart transformer for this purpose. These are a dime-a-dozen at garage sales around here. I have even broken off the plastic case and used just the transformer to get rid of the rectifier in a DC output wall-wart.Why not use a low-voltage transformer and measure the output from that? Much safer. The output voltage will be a fixed fraction of the mains voltage.
No, the AC is a sinusoidal waveform. Mains line voltage is normally specified as the RMS (0.707 * E peak value). So the RMS value is equal to the DC value. However, if a cap is added following the full wave rectifier then the DC level will be 1.414 * RMS value or in your case about 325 VDC.i am sorry 230v not 220. I am using a rectifying bridge to convert the Ac to Dc (since i havent found an opto coupler which takes direct ac input) and the i read somewhere that the DC output is ~.070 AC. Is that right?
My understanding is you just want to "sense" and not measure the mains voltage, the mains voltage is there or it isn't, Yes or No. I would just do as suggested and use a plain old simple wall wart adapter as was suggested. Safe, simple and inexpensive.I want to sense the voltage at the outlet(indian). I want to make it as accurate as possible.
i would like to use an ardiuno and the measure the voltage. Apologies, i should have mentioned that i was connecting the optocoupler to the ardiuno.No, the AC is a sinusoidal waveform. Mains line voltage is normally specified as the RMS (0.707 * E peak value). So the RMS value is equal to the DC value. However, if a cap is added following the full wave rectifier then the DC level will be 1.414 * RMS value or in your case about 325 VDC.
My understanding is you just want to "sense" and not measure the mains voltage, the mains voltage is there or it isn't, Yes or No. I would just do as suggested and use a plain old simple wall wart adapter as was suggested. Safe, simple and inexpensive.
Ron
Thats good to know. Could you suggest some optocouplers which could be used?What is it that you want to "sense"? Presence/absence, peak value, RMS value, frequency, current - ??? Except for current, all of these can be "sensed" through a transformer with more safety and accuracy than with an optocoupler. And BTW there are AC input optocouplers that have two back-to-back LEDs internally. Like all opto's, these cannot be connected directly to an AC mains without current limiting and transient protection, but they can eliminate the need for a bridge rectifier in some applications.
ak
i would like to sense the value of voltage a device derives from the outlet and read it through the arduino.Thats good to know. Could you suggest some optocouplers which could be used?
Yeah, that sort of changes things quite a bit. I would use a transformer to reduce the 230 VAC to a low DC level like 5.0 VDC. Just a matter of a full wave rectifier, a linear 230 VAC to 5 VDC would likely do fine. I would then do a simple test to make sure the wall wart was linear using a variac to drive the wall wart. In theory if 230 VAC provides 5 VDC then 115 VAC for example should provide around 2.5 VDC. The DC from the wall wart goes to your Arduino AI (Analog Input). Then do the math in the code.i would like to use an ardiuno and the measure the voltage. Apologies, i should have mentioned that i was connecting the optocoupler to the ardiuno.
by Jake Hertz
by Duane Benson
by Jake Hertz
by Jake Hertz