How does the software know what the step down ratio is?
Submitted by Guest on Mon, 28/11/2011 - 09:37
I've been busy building the Version 2.0 of the meter and have a query on the step down transformer.
In your project you use a transformer to step down the voltage to 9V and then use a voltage divider so that the ardiuno can take voltage measurements at a max 1v peak to peak.
What I dont understand is where these values get scaled back to 240V. Since the transformer is dropping from 240V to 9V shouldnt the value sampled be multipled by 2.66? Does the "factorB = 777.75" take care of this? I think I got lost in trying to understand all the formulas :)
I've build the circruit and have it running using a 6VAC transformer - I'm getting a reading of round 435Vrms with a 240V mains supply?
I haven't yet calibrated it yet as I dont have a true RMS meter - is there another way around this? What else can I use for this?
How does the software know what the step down ratio is?
Submitted by Guest on Mon, 28/11/2011 - 09:37I've been busy building the Version 2.0 of the meter and have a query on the step down transformer.
In your project you use a transformer to step down the voltage to 9V and then use a voltage divider so that the ardiuno can take voltage measurements at a max 1v peak to peak.
What I dont understand is where these values get scaled back to 240V. Since the transformer is dropping from 240V to 9V shouldnt the value sampled be multipled by 2.66? Does the "factorB = 777.75" take care of this? I think I got lost in trying to understand all the formulas :)
I've build the circruit and have it running using a 6VAC transformer - I'm getting a reading of round 435Vrms with a 240V mains supply?
I haven't yet calibrated it yet as I dont have a true RMS meter - is there another way around this? What else can I use for this?