I had been eying up Arduinos and looking into getting started with digital electronics for a while and now finally brought an Uno along with a 16×2 character LCD with RGB backlight. Wow. It’s like I’ve unlocked a whole new world of electronics, for years I’ve looked at digitally controlled devices like LCDs woundering how I could use them, finding out that I need some sort of microcontroller and then having to forget about the idea as I thought that would be way out of my league, not any more, hooking up the LCD was so easy with Arduinos LCD library, I quickly made a stereo audio VU meter and a basic FFT spectrum analyzer.

This is a simple 555 timer based circuit which can jam IR (Infrared) communications like TV remotes, when I first made the circuit (October 2011) it was a bit iffy at jamming IR and eventually stopped working for some reason, it wasn’t until recently that I brought a mini DSO and found out it needed at least 6.5V to reach 38KHz with the 10nF capacitor (lower capacitor value will allow a lower supply voltage), the 9V battery I was using at the time was running out and couldn’t supply enough power to reach 38KHz! Once hooked up to a clean 9V supply and tuned to 38KHz with the help of the mini DSO the jammer worked flawlessly. :D

I haven’t really used LEDs all that much other than as power indicators or in a joule thief, perhaps it time to make some pretty flashy things. 😀

Here I made 3 slightly different PWM fan controllers based on the 555 timer for controlling a large server fan – Delta FFB1212EHE, 3A peak, 2A normal load, other features of these controllers are to boost the fan on to 100% for the first few seconds of receiving power and a ‘turbo’ button to set fan speed to 100% while pressed.

In case you’ve not heard of a joule thief before, they’re simple voltage boost circuits, usually used to drive light loads like LEDs with a single battery cell. Even batteries that other electronic devices consider ‘dead’ can be used.

Here’s a nice little FM radio transmitter, it has a range of about 100m – 200m with a 12V supply, decent audio quality and the microphone is very sensitive, with a 5pF – 30pF variable capacitor the transmitter can tuned between 87.5MHz – ~98MHz, however at the higher frequencies it’s much less stable and more difficult to tune. As the transistors and capacitors heat up the frequency changes, the heating is only a small amount and Q2 is the main one that does the heating.