An experimental HF 6-band SSB transceiver

Peter (DK7IH) has been working on HF 6-band SSB transceiver: Part 1: Project Basic Outline Presentation Part 2: The Oscillators (VFO, LO and Testtone Osc.) Part 3: The Microcontroller (ATMega128) Part 4: Bandswitching Logical Circuits Part 5: Measuring Transceiver Data Part 6: The Receiver Part 7: The Transmitter Part 8: Transmit/Receive Switch Unit Part 9: […]

Ionization chamber

Robert Gawron has posted an update on his Ionization chamber project we covered previously: Ionization chamber is a device to measure radioactivity level. When air’s atoms are hit by radioactive particles, an ion-pair is produced. Ions has electric charge, if they are in electric field create by positive and negative electrodes, negative ions will move […]

Simple VU-meter circuit

VU-meter circuit built on a breadboard using transistors, diodes, resistors, and LEDs @ Build Electronic Circuits: It’s basically a simple display for showing a value. It’s originally for showing signal level in audio circuits, but there’s no reason you can’t use it to show temperature, rain intensity, light level, or whatever other value you are […]

DIY cloud weather station with ESP32/ESP8266 (MySQL database and PHP)

A how-to on building cloud weather station with ESP32/ESP8266 @ Random Nerd Tutorials: Build a cloud weather station dashboard to visualize your ESP32 or ESP8266 sensor readings from anywhere in the world. You’ll see your sensor data displayed on gauges and on a table. The ESP32 or ESP8266 will make an HTTP POST request to […]

Building an extremely high powered 1-12V lab power supply on the cheap

Matthew Millman has published a new build: For a number of years now I’ve had a couple of high powered switching power supply units made by Power-One. They’re typically found in I.T. equipment and provide a single output rail of either 12 V or 48 V with a very high current rating. The other cool […]

Building your own Mini flight recorder

Pinko designed and built his own mini flight recorder: For a while a wanted to make my own flight recorder similar to the commercial altimeters but with my own requirements for functionality. In addition it needed to be visually appealing and functional in the same time … After some thinking about the design and functionality […]

Automatically re-connecting low-voltage cut-outs for 12 and 24 volt battery systems

KA7OEI writes: In a previous post I described a simple circuit that provided a low-voltage cut-out that could be used in a battery-operated system – see the article “A latching low-voltage disconnect for 12 volt lead-acid and lithium batteries”. That circuit – intended mostly for lithium-based batteries – required manual intervention to “reset” the device, […]

Homemade injection transformer for PSU loop analysis

Adil Malik made a DIY injection transformer for PSU loop analysis: Recently, I have been designing some SMPS and required some hardware to measure the actual loop response of the complete converters. People familiar with this area will probably know this can be done breaking the feedback loop of the converter and injecting a small […]

Building a Power-over-Ethernet (PoE) power supply using a DPS5005 module

Dr. Scott M. Baker has designed and built a PoE-powered lab power supply using a DPS5005 and custom PoE board: The DPS5005 is a DC-DC converter. It can accept an input voltage from 0 to about 55 volts or so, and will regulate an output voltage up to about 1 volt below the input. This […]