Karl Berger

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  1. Sending APRS Analog Telemetry – The basics — 1 comments

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E-Bike Energy Consumption

E-Bike with added rear rack and paniers

Anticipating a lot of spare time and with rare good foresight, I bought an electric bicycle at the beginning of the COVID19 lockdown. I wanted a folding model so that it could be put into the car trunk and big wheels because the small-wheel folding bikes look strange to me. The Ancheer 26-inch folding mountain …

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Permanent link to this article: https://w4krl.com/e-bike-energy-consumption/

E-Bike Logger

E-Bike Logger mounted on handlebar extension

Soon after I got my Ancheer 26-inch folding electric bicycle, I built a data logger that directly measures battery voltage and current, and calculates wattage. It also records calculated energy consumption in terms of ampere-hours and watt-hours. It records this data on a microSD card every second. The datafile can be opened in a spreadsheet …

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Permanent link to this article: https://w4krl.com/e-bike-logger/

ESP32 Analog To Digital Conversion Accuracy

The ESP32 is a powerful microcontroller with many input/output ports. Specifically, it contains two 12-bit multiplexed analog to digital converters (ADCs) for a total of 18 channels. ADC1 is attached to eight GPIOs from 32 to 39. ADC2 is attached to 10 GPIOs (0, 2, 4, 12 to 15 and 25 to 27). There are …

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Permanent link to this article: https://w4krl.com/esp32-analog-to-digital-conversion-accuracy/

Zambretti Forecaster

Zambretti Forecaster (rear)

The Zambretti Forecaster is a weather forecasting tool in the form of a circular slide rule introduced in 1920.  It claims to accurately predict near-term weather based on barometric pressure, the trend in the pressure (rising, steady, or falling), and wind direction. It relies on the fundamental meteorology of pressure fronts. Watch any TV weather forecast and …

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Permanent link to this article: https://w4krl.com/zambretti-forecaster/

Sending APRS Analog Telemetry – The basics

The amateur radio Automatic Packet Reporting System (APRS) is typically used for position and weather reporting. It can also handle eight digital and five analog telemetry channels. The IoT Kits© solar-powered weather stations have four APRS analog telemetry channels for LiPo cell voltage, time awake, WiFi signal strength, and light intensity. Four digital channels are used …

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Permanent link to this article: https://w4krl.com/sending-aprs-analog-telemetry-the-basics/

DIY Instrument Shield

An instrument shelter provides a flow of air around weather sensors while protecting them from direct sunlight and rain. Without a shield, the sun can heat the temperature sensor giving a false high-temperature reading. Professional weather stations use a large louvered box called a Stevenson Screen that is built to specific dimensions for standardized weather …

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Permanent link to this article: https://w4krl.com/diy-instrument-shield/

Solar Radiation Shield under test

The D1M-WX1 and D1S-WX1 solar-powered weather stations heat up in direct sunlight giving an incorrectly high-temperature reading. Early results from testing an Acurite solar radiation shield are very good. The shield is available from several online vendors. Check around for a good price as the same item sells for $10 to $60 from different vendors. …

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Permanent link to this article: https://w4krl.com/solar-radiation-shield-under-test/

Cheap (not so good) power supply

Most electronic projects operate on low voltage direct current. This is often provided by a USB connection or a battery. There are several possibilities to power a project from the 120 Vac power line. A common way is to use a wall adapter (wall wart) and feed low voltage direct current to your project through …

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Permanent link to this article: https://w4krl.com/power-supply-measurements/