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Hardware & energy tools

Reference pinouts and the power and energy sums that come up at a bench. Every formula is shown, and every default can be replaced with your own measurement.

Reference

Pinout lookup

RS-232, Raspberry Pi GPIO, ARM SWD/JTAG, ATX, RJ45 and USB, drawn as the connector looks, with levels and a multimeter check.

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Power & thermal

PSU & thermal calculator

Size a PSU with headroom from a parts list, and get heat output in BTU/hr, enclosure airflow and yearly energy cost.

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Batteries & energy

Power bank real capacity

Why a 20,000 mAh power bank does not deliver 20,000 mAh, and how many charges you can really expect.

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Battery runtime

How long a battery bank, UPS or power station runs a load, allowing for depth of discharge and inverter losses.

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Appliance energy cost

What an appliance costs to run per day, month and year, including standby draw.

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Solar panel output

Daily and yearly energy from a solar array, and how many panels cover a daily need.

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Troubleshooting

Solar inverter fault finder

Grid, isolation, battery and arc faults by symptom: likely causes, safe checks, and when to call an installer.

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How this works

Every sizing rule, formula and assumption behind these tools is written up in the documentation — including what they deliberately leave out.

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Why these run in your browser

Everything on this site runs in your browser. What you type is worked out on your own device and is never sent to a server, so the tools keep working offline once the page has loaded.