I recently ordered an EzTV666 USB DVB-T stick from eBay. People have found out you can use these sticks as Software Defined Radios (SDR) which can receive radio signals in a very wide range of frequencies. The particular model I got has RTL2832 chip with an Elonics E4000 tuner chip. You can tune it from 64MHz to 1700MHz (with a small gap around 1150MHz). I needed to build an antenna for it and a […]

A few weeks ago I was on a junkyard that had a decent amount of telecommunications equipment. Mainly racks of old cellphone 3G (I think) basestations from which I got a load of some interesting RF stuff. I also found a pretty rough looking switchmode power supply from the ground, made by Ascom energy systems. It had been sitting out in the rain for quite some time (I think at […]

Here’s a quick project I made in couple days or so. It is a push-pull step-down laser diode driver based on LT1683 SMPS controller chip from Linear Technology. The circuit works with 12-18V input and can put out about 1A to a 2V load. I used a PL140-105L planar ferrite transformer from Coilcraft which is quite overkill for this application (it is rated for 140W). The circuit has a current clamping circuit (so […]

I spent the whole yesterday battling with an ATMega16U4 microcontroller. I was trying to set the fuses to use the internal RC-oscillator instead of the external crystal oscillator. In the end I had to modify my avrdude.conf but the problem with the fuses ended up being pretty simple… Adding support for ATMega16U4 to avrdude Well the first problem was that even the SVN version of avrdude does not seem to […]

I designed a PCB for a programming box (based on OlliW’s original schematic) for the Assan GA250 gyro flashed with OlliW’s custom firmware (see my original post about flashing your gyro here). The programming box hooks up to your gyro and enables you to tune the parameters on the field. The design is really simple, it basically has an ATMega8, four buttons, 16×2 HD44780 compatible LCD and some auxiliary stuff. The […]

I got around setting up a GitHub repository for the driver library for the OLED-displays I did a post about before (this). The library currently supports printing 5×7 font characters and turning single pixels on and clearing the whole display but I will keep working on it and add features as I go. What I’ll add soon is support for larger fonts and arbitrary font placement (currently you can just write […]

I needed a display for a project of mine and was just going to use a regular HD44780 -based text LCD display, until I spotted some very neat looking TINY OLED-displays from eBay. The displays are monochrome 128×32 pixel displays with a 4-wire SPI bus and they are around 30x11mm in size (the actual display area is under an inch diagonally!). The exact type of the displays is UG-2832HSWEG04. I found […]

Edit: Schematic had a bug, the INT pin on the DS3234 should be connected to pin 2 on the arduino, not the 32kHz pin! I updated the schematic. I bought a small aquarium (54l) as an impulse buy and I needed some lights for it, so naturally I wanted to use LEDs. I also needed a timer for the lights. I also wanted the lights to fade in and out […]

Every once in a while I’d have needed a function generator but since I didn’t have one I always had to resort to some sort of quick and poor 555 kludge or something similar. I spotted a nice looking DDS (Direct Digital Synthesis) kit meant for the Juma RX-1 receiver that uses the AD9833 DDS chip. I figured I should be able to use it as a function generator because the frequency range […]

I’ve been thinking about making a temperature logger for my room and my computer, I set on using DS18S20 sensors from Maxim because they’re common, cheap and overally pretty ideal. My computer is so new that it does not have a serial port (not 100% sure, I think there might be a pinheader on the motherboard with serial port connections) so I have to use USB for interfacing. Next thing […]