For my first cosplay I selected something that is easy and fast to make. All the pieces were first carved out of thicker (8 cm) insulation foam, thereafter sanded with sandpaper and colored at the end.
Before painting, the foam has to be coated with protective coating to eliminate damage to the foam done by used paint. I did this using two layers of the wood glue. Other thing can be used as well.
For the skull that represents guitar’s headstock I used ball made of Styrofoam. First it was carved out to fit the guitar handle and then painted it with white color. Details are painted in black.
Guitar strings are made of the rope painted in black.
My Nikon DSLR camera does not have any internal programmable mode for continuous shooting (intervalometer) or socket in which wired remote shutter could be plugged in. The only way you can make exposures longer than 30 second is using IR remote. If you want to take only a few pictures, this is not a problem. But when you want to make a time lapse few hours long or photograph a meteor shower for whole night, this is no longer convenient. Especially when you want exposures to have the same length and the same interval between them, this can be very challenging.
That is why I took one of those cheap IR remotes and upgraded it using small ATtiny85 microcontroller. Its task is to simulate button presses depending on the settings of the DIP switch. The element in use consists of five switches. The first one (1) is used for selecting the operation mode. When switched ON continuous mode is selected and long exposure mode when it is turned OFF. Other four switches (5-2) determine the length of exposure or interval. You can change the settings during exposition, but they are not taken into account until the next exposition.
Long exposure options – DIP switch 1 is set to OFF:
DIP switch 2 ⇒ 10 min
DIP switch 3 ⇒ 5 min
DIP switch 4 ⇒ 2 min
DIP switch 5 ⇒ 1 min
Total maximum time for a long exposure, when all switches are turned ON, is 18 minutes.
Continuous shooting (intervalometer) mode options – DIP switch 1 is set to ON:
DIP switch 2 ⇒ 120 s
DIP switch 3 ⇒ 60 s
DIP switch 4 ⇒ 30 s
DIP switch 5 ⇒ 10 s
Total maximum interval between two exposures in continuous shooting mode, when all switches are turned ON, is 240 seconds.
Button presses are simulated using MOS N-FET 2N7000 transistor (see the bottom image for wiring diagram). When pin 1 goes to HIGH the transistor opens and concludes an electric circuit that provides power to IR remote circuit.
My sister brought home some fancy hight-tech Gelish Gel Polish that must be cured using a very expensive UV LED lamp. I was interested in how the gel work but could find any description. To ensure proper application of the the gel you have to follow more than 10 steps and apply different kind of polishes and cure them with this lamp. The interesting part for me was the lamp itself. It does not look anything special just an 10×3 array of 30 LEDs and a timer switch. Unfortunately I was not allowed to open the device because it is still under warranty and sister would not be happy if anything should go wrong in the process.
I presume that the circuit board inside has very simple design. To replicate it you need a bunch of LEDs, some resistors to limit the current through them and an optional timer circuit. My intention was precisely that, to make my own cheap version of the original lamp. The result is this simple 8×4 array of 32 diodes.
Recently acquired USB TV tuner and antennae that I built for it had to be put into use. For some time it is fun just to listen to nearby radio and aircraft communications. In addition, I wanted to do something useful. I thought of an old weather station that is constantly (every 30 seconds) sending data to an indoor unit on a 433MHz frequency.
The 433 – 434MHz ISM band is full of various short messages from different commercial gadgets. To figure out the exact frequency of my wireless sensor I put it close to the receiving 400MHz discone antenna (for ensuring the strongest signal), and observed the spectrum of the band using SDR# software.
After obtaining the frequency it was time to record signals at different sensor temperatures and settings (audio sample 1, audio sample 2). The channel switch does not really change the working frequency but only changes a few bits in data stream as will be shown below.
Recorded audio was imported and processed by Matlab’s function wavread and then plotted using plot function. The received signal consists of wake up pulse followed by a pause and eight or nine data bursts. The last data burst varies in length for a reason that the entire signal is always the same length.
The picture above shows one of those data bursts. While watching this picture I started thinking about the way how to decode the signal. The first thought was to read signal peaks as ones and wider gaps between them as zeros. Processing few different temperature readings gave me following bits:
It looks like the message is not decoded as simply as I hoped. Something else must be behind because the messages have different numbers of bits. After some time and mapping options I found the correct one. Bits with value 1 are mapped to 0 and set of bits 10 as 1. This gave me much better results, messages that have the same bit lengths:
That way I was able to group bits into meaningful groups. Detailed process of the decryption will be shown for the temperature values 18.7°C and -1.9°C. For better visibility message must be first broken into seven groups.
0011 01001100 000010111011 11 1 0 0 equals to 18.7°C
0011 this part changes for every different temperature reading, probably some kind of CRC/checksum code, have not yet manage to decipher it
01001100 random sensor serial number, it changes every time your restart the sensor
000010111011 converted from binary to decimal gives us 187, divided by 10 returns the correct value of 18.7
11 channel number, possible variants are 01 for CH1, 10 for CH2 and 11 for CH3
1 battery indicator, 1 battery OK, 0 low battery
0 indicates the sensor normal working mode. You can force it to send data by pressing TX button on it. At that time this bit will change to 1, telling the indoor unit that you forced the sensor to send data and maybe changed the channel setting.
0 tail constant every time
0111 01001100 111111101101 11 1 0 0 equals to -1.9°C
111111101101 is the two’s complement of the sensor reading, first -1 must be subtracted returning 111111101100, this is then inverted to 000000010011 and converted to decimal values giving 19. Taking into account the sign and the division factor 10, the result is -1.9
I decided to upgrade the previous circuit with additional capabilities and intelligence. Using IR remote controller, relay and clock module it can be transformed into simple home automation system. Whereas the previous Arduino chip was lacking required ram space and I/O pins there was a need to add another one to the circuit board and to establish the serial link with the previous one that is managing the LCD display.
First thing needed was to figure out what HEX values the remote in use is producing to communicate with the device. I am using a remote that was bundled with USB TV-tuner, which is mainly used in another room. My remote has a total of 29 buttons however I am only interested in the fraction of them, here are the HEX values in use obtained for my remote.
A05F807F – Power
A05F906F – Num 1
A05F50AF – Num 2
A05FD02F – Num 3
A05FB24D – Display
A05FE817 – REC
A05F18E7 – Stop
A05FB847 – Fwd
A05F38C7 – Back
A05F6897 – Play/Pause
The next thing to figure out was how to control the 8-relay module. Every relay in this module has 3 screw-type pins to control the high voltage AC current named NO(normally closed), NC(normally open) and COM(common connection). The 220/110V AC input must be connected to COM. The switch inside the relay is moved by the electromagnet that is indirectly connected to one of the Arduino ports. When the relay is turned off the COM is connected to NC and when turned on connected to NO. I am using the relay with revered logic which means that the relay is turned on when port is set to LOW. For every relay there is an on board LED that shows if it is active. The module has additional safety factor as all the relays are optically insulated, this means that all Arduino really does is turn on an LED inside an optocoupler, and that turns the relay on. So far I am using the relay module for switching the lights in my room, further applications are on the way.
Another novelties on the board are DS1307 RT Clock and piezo buzzer. Clock and buzzer together, combined with way to turn on/off the light bulbs in the room can be used for a brutal alarm clock.
Ever wonder if that inexpensive laser collimator is really doing what it should? I never really trusted them, therefore I put mine on test one day. The first thing I had to build was V-shaped holder made out of wood, to prevent the collimator from moving around during tests.
Next I nailed the holder on to the wooden table to stabilize it and put the turned on collimator in v-shaped notch. 5 meters away (farther is better) where the laser beam was shining on the wall I attached a white paper for markings. Now rotate the laser collimator and see if the beam is making a circle or it stays a dot. If it stays in one place, your collimator is in perfect alignment. As you can see from the markings on the picture, my laser beam was making a circle. Using the two small allen adjustment screws at the back of the collimator move the beam so that it is pointing in the center of the marked circle and rotate it again. Repeat this until the beam remains in place while rotating the collimator. It took me about 5 iterations.
That’s it. You have successfully realigned you laser collimator, now use it with confidence for aligning your telescope optics.