A low-cost approach on a Wattmeter using a single-phase split-core current transformer and PIC16F628A. The prototype performed the most accuracy when the Input Voltage is around 4 to 5 Volts.
The project utilizes the built-in comparator of PIC16. The configuration charges to capacitors up to 2.5 Volts then discharges and recharges it for 1024 cycles to achieve a 10-bit resolution accuracy.
| voltmeter reading | adc voltage | adc reading |
|---|---|---|
| 1.98 | 2.04 | 409 |
| 1.96 | 2.09 | 419 |
| 1.96 | 2.09 | 419 |
| 1.97 | 2.09 | 419 |
| 1.97 | 2.09 | 419 |
| 1.97 | 2.09 | 419 |
| 1.97 | 2.09 | 419 |
| 1.98 | 2.04 | 409 |