Making MIDI hi-hat controller from unused bass drum pedal

Recently one of my friends bought an electronic drum set made by polish manufacturer "DIG DRUM". The drum set is very good and combined with the Alesis triggerIO works really well.

Unfortunately the pedal for controlling the hi-hat open/close signal was not included in the set. After a quick search, I've discovered that the circuit for the controller is trivial, so I decided to build my own.

The circuit for setting the pedal state consist only off a potentiometer and a cable which connects it to one of the IO ports of the trigger interface. You can find the diagram on this page.

For the pedal I've used a part of a twin bass drum pedal set, which was no longer used.
In order to be able to rotate the potentiometer, it needs to be mounted to the axis off the pedal. To achieve that I've created a stand from a piece of plexiglass and a metal plate.

The stand with the potentiometer and the socket:

The potentiometer is connected with a 1/4 stereo jack socket using a short wire:

The part which connects the axis of the pedal with the potentionemter. A few screws and metal pads mounted together:

...and the whole construction:

It works pretty well for now, but I suppose that the potentiometer will not live for too long in this kind of application :-)

Battery powered hands warmer

If you ever had your hands frozen in the winter, you may be glad to have this simple battery powered hands warmer made from junk.

IMPORTANT: I take no responsibility for any injuries caused by anything you build using this guide. Everything you do is for you own responsibility. Be aware that this device may cause burns and heated batteries can explode !!!

To build this simple, yet useful device you will need:
- old PC power supply
- plastic 3 x 1,5V battery pack
- some resistors
- wires, solder, soldering iron

The most important element for the heater is the radiator with a power transistor that you should find in almost any PC power supply. You will need to unsolder the transistor together with the radiator. Mine was TT2140 which you can see on this image:

The circuit is very simple, it includes only the transistor and a 25 Ohm resistor. The value of the resistor may be different for different transistors. I suggest trying different values between 10 and 150 Ohm and measuring the current from the battery. The current should not be too high because the batteries will start heating instead of the transistor (and check if the temperature isn't too high for your hands). In my case I used two resistors paralleled, because I didn't had a 25 Ohm one.

Some more views of the heater:

Have fun and be safe !

Arduino + ikea box + flightgear = flykeaduino

Hello there. It's been some time since my last post. I got some new stuff and ideas meantime so it's time to share something.

Recently I have played flightgear a lot, it is a very good open source flightsim and it has some usefull abilities. One of the most usefull things is that flightgear provides access to simulation parameters via telnet ! Using it for making own control system was really easy.

First I've wrote a simple app for arduino to utilize six switches and one potentiometer. Arduino sends the data about switches state using serial. You can download the code here.

Next I've used a box from ikea some wires and soldering iron to make a simple control panel. The switches are connected in the most basic way. Every switch has +5V, ground and one digital input pin connected. The potentiometer is connected in the same way except that it uses  the analog input pin.

The data from arduino is parsed by python script which connects to flightgear by telnet and sets proper values for various controls. You can find the script here.

Usage:
- connect arduino, compile and flash the app
- run flightgear with  "--telnet=5401" argument
- run the python script
- done ! use switches and buttons to control flightgear

Have fun :)

555 earrings

I've made a pair of very special geek-earrings for someone very special to me :). They are based on a 555 timer, LED, couple of resistors and a capacitor. All soldered to take as little space as possible.
They will be probably knitted out or transformed in some other way to be more girl-friendly.

Here you got the circuit and photo:
(555 chip on the circuit is upside down)

555 timer earrings