CT Clamp Burden Resistor Selection and ADS1115 Calibration
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Comparison
| Part | Role | Interface | Verdict | Price |
|---|---|---|---|---|
| Split-core CT clamp (x2) | Current sensing on both 120 V legs of the panel | Analog into ADS1115 A2/A3 | conditional | — |
| JANSANE SCT-013-000 100 A split-core CT clamp. Works, but a split core that is not fully closed reads low silently. Calibration constant is empirically fitted. | ||||
| ADS1115 16-bit I2C ADC breakout | Reads the two CT clamps (channels A2/A3) for whole-house current | I2C, single-ended A2/A3 | conditional | — |
| HiLetgo ADS1115 16-bit 4-channel I2C ADC. Fine for relative load trends; 860 SPS is ~14 samples/cycle at 60 Hz, so harmonics alias. | ||||
| Raspberry Pi 4 | 1-Wire master + villa collector | dtoverlay=w1-gpio; SQLite timeseries.db | yes | — |
| Used in the running shed build; works reliably. |
Verdict
Pick the part that matches your interface and accuracy needs. If you need humidity, prefer BME280 over BMP180. For long 1-Wire runs, DS18B20 is the most robust choice.
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Related reading
- SQLite Rollups and Retention: Stop Your Sensor DB From Eating the SD Card
How rollup tables and a retention policy keep a Raspberry Pi sensor SQLite database from growing unbounded — and why SD-card wear is rarely the real problem.
- CT Clamp Burden Resistor Calibration for ADS1115: Avoiding Voltage Drift in Home Sensor Projects
A practical guide to calibrating CT clamp sensors with ADS1115 ADC, covering burden resistor selection, capacitor stabilization, and common failure modes in home sensor projects.
- HC-12 Packet Loss and Retry Protocol
The HC-12 433MHz serial bridge has no built-in retry or CRC at the UART passthrough level. Here is a practical application-level framing scheme with CRC-16, timeout-based retry, and backoff that actually worked on a live link — plus what went wrong.