In the AC voltage measurement circuit of the Energy Monitor, electrolytic capacitors are installed. Can they be replaced with non-polar ceramic capacitors or polar tantalum capacitors of the same capacitance?
What exactly are you talking about? One of our energy monitors you’ve copying from Github? The circuits in the Learn section of Docs? Something else?
I know you’re new here (and welcome aboard), but remember, we can’t know what’s in your brain.
Firstly, I don’t advise you copy that arrangement, because when used with a switched-mode power supply, it is susceptible to picking up r.f. noise generated by the SMPS. (I never did understand why that arrangement was used.) Rather you should use the arrangement we now use in the emonTx4 and Pi2, further down the page, where one side of the a.c. adapter is grounded.
Ceramic capacitors are not advisable, because the capacitance value varies widely with the applied voltage. Tantalum electrolytics will be fine, albeit more expensive.
You can change the values of R1 & R2 to suit the voltage from your transformer. Beware, the voltage of small transformers is specified at full load, when used with almost no load (as here), the voltage is very much higher. The 9 V rms adapter we used to use had an output of 11.2 V rms.
Thank you for the clarification. This circuit has been working successfully for several years without any issues. No-load voltage on the transformer is 10 V.
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