flip-flop/BCF project


Ray over at the diyAudio forum has been working on his flip-flop/BCF project:

I’ve just finished a project to roll up the developments into a more ‘finished’ build, feeding the balanced outputs from the flip-flop board into a Broskie BCF buffer stage. I’m using Nicks MJ Statistical Regulator for the B+ and one of Andrew’s indirect filament supplies

Project info at diyAudio forum.

Building a low cost wifi camera


Johan Kanflo designed a Esparducam board and built a low cost wifi camera with an Arducam Mini and a ESP8266 Wifi module:

Sometime ago I came across the Arducam Mini which is quite a nice camera module from UCTronics. It is a small PCB with a two megapixel OmniVision OV2640 sensor, an interchangeable lens and an FPGA to do the heavy lifting of image processing and JPEG encoding. Priced at around 24 Euros (lens included) you can easily buy a few without hurting your wallet and combined with an ESP8266 you can build quite a low cost wifi camera. Or several. Because designing and building PCBs is both fun and inexpensive I designed a board to go with the ESP8266/Arducam Mini combo, aptly named the Esparducam. And uniquely named too, try googeling for “esparducam“. Heck, even the domain name is available at the time of writing :)

More details at Johan Kanflo’s blog.

Project files are available on Github.

Arduino MPPT solar charger shield


Lukas Fässler made an MPPT solar charger project and wrote a post on his blog detailing its assembly:

The basic idea behind an MPPT solar charger is simple. A solar panel has a certain voltage (in the region of 17 to 18 volts for a 12 volts pannel, somwhat dependent on temperature) at which it provides most power. So as long as the battery needs charging, you want to pull just as much current to reach this voltage. But once the battery is full you need to avoid overcharging the battery. So you want to maintain a maximum voltage for your battery (somewhere around 13.8 volts for a 12 volt lead acid battery) and no longer care about the pannel’s voltage.

Project info at Soldernerd site.

Simple small QRO for HF


Marko Pavlin has been working on a HF amplifier project:

I followed the ARRL Homberw challenge 50 watt aplifier entry. It is low cost, simple HF linear amplifier designed and built by the author as an entry in the ARRL’s 2009 Homebrew Challenge contest. The requirements of the amplifier were: 40 meter band 50 watt output amplifier intended for use with a QRP transmitter as driver (less than 5W), constructed at a total material cost of not over $125.00.
I redesigned author original design an put it on the double sided PCB with additional output banpass filters. I started with first prototype. It worked quite well for short periods. Main disadvantage was lack of heat sink. Then I soldered second prototype with proper transistor cooling. I also wound correct transformer using binocular ferrite cores
Next step was designing PCB. I started with the schematic diagram based on original project

Project info at Mare & Gal Electronics homepage.


ESP8266 mains energy monitor


A ESP8266 mains energy monitor project by Brian Dorey:

 As the new solar logger did not have this functionality we decided to design a new data-logger that would measure not only the mains current usage but also keep track of the electric meter and gas meter so we can easily see how much energy we are using in the house.
The new mains energy monitor was designed to be a standalone box that would be powered from the mains and have sensors for the mains current, electric meter and gas meter. As we didn’t want to run any more wires around the house we also decided to make it wireless connecting to our network over Wi-Fi.

Project info at Brian Dorey’s blog.

Mullard 3-3 amplifier project (part 1)


Dilshan Jayakody has published a new build, a Mullard 3-3 amplifier project:

Mullard 3-3 is quiet popular 3W tube amplifier introduced by Mullard Ltd in 1956. A schematic and design detail of this amplifier is available in “Mullard Circuits for Audio Amplifiers” book and in National Valve Museum article. This amplifier is based on EF86, EL84 vacuum tubes and EZ80 full wave rectifier tube. In this project we decided to construct this original Mullard 3-3 Amplifier with some slight changes and commonly available electronic components.
In our prototype we replace EZ80 tube with 400V 5A bridge rectifier which is commonly available in many electronic spare parts shops. Also we replace EL84 with 6P14P pentode and EF86 with 6J8 pentode. Both of these valves can directly use with this circuit and those values are available for lesser price than EL84, EF86 tubes.

Project info at Dilshan Jayakody’s blog.