Home

Hello, I am Karl Berger, the owner of this site. I am a licensed Professional Engineer (Electrical), a Life Senior Member of the IEEE, and holder of the Amateur Extra callsign W4KRL.

I design and sell IoT Kits©. These are low-cost, simple kits that can be built with common tools. Most kits use microcontrollers, typically the D1 Mini, ESP32, or Arduino Nano. The hardware and software are open-source. All development software and online services are free for hobbyists and non-commercial users. Assembly and programming of the kits is cookbook style with detailed explanations provided so that you can learn how the devices work. I generally program in the Arduino dialect of C++ so there are many online sources for support and education.

Take a look around the site. I suggest stating with the IoT Kits page. You do not have to register to use the site, however, only registered users can post comments. I will never share your e-mail address with anyone. Occasionally, I may send users notices of new products or updates of kit software. You may opt out at any time.

Permanent link to this article: https://w4krl.com/

Zambretti Forecaster

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 …

Read more

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 …

Read more

Temporary Station using DIY Solar Shield

It has rained since we arrived at Bethany Beach, Delaware for vacation so it has not been able to test how well the DIY solar radiation shield performs in sunlight. It is hung on a small twig of a tree in the backyard. ThingSpeak feed: https://thingspeak.com/channels/430753 APRS Feed: https://aprs-fi/W4KRL-13

Read more

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 …

Read more