Medical equipment is expensive and not always accessible for wide audience. In fact in any biomedical measuring instrument there are nothing very special – here you can find ADC, analog front-end with low noise op-amp, some sort of controller. But the main part what makes it different from consumer electronics is safety. Because device is connected to your body through some sort of electrodes, there is always a risk of electric shock. So power supply has to be isolated if it is powered from mains. There might be other additional safety circuitry to prevent possible hazard. And of course there are many safety regulations ans certificates to overcome before device can be used with patients. This is where main cost comes from. It doesn’t mean that you cannot experiment with your body signals. You only need to know what are you doing. If you are building your own circuit to …
Ultrasonic echolocation is common practice in many areas including nature itself. We all know how bats or dolphins navigate – they emit ultrasonic waves and depending on time delay of reflected echoes, they can determine the distance from obstacles or catch. From engineering perspective it is relatively easy to measure distances with ultrasound – all you need to know is sound speed in the air and time delay between sent and received pulses. L is the measured distance; CAIR – ultrasound speed; t – time between transmitted and received pulses. The accuracy of measured distance mainly depends on air temperature. Approximately sound speed in air can be calculated by following formula: For instance at 25ºC the speed of sound in dry air CAIR = 346.13 m/s. So if you want greater accuracy, you should also measure temperature to adjust sound speed.
Arduino is a great platform for fast prototyping and building projects. But probably one of the best things here is, that Arduino layout allows plugging hundreds of standard shields. Today you can probably find any type of sensors, displays, drivers included in to shields. This is where comes the real power of using Arduino. Gearbest have supplied us with a great combination of commonly available products including Arduino Mega2560 and LCD keypad shield. Arduino Mega2560 comes with powerful AVR ATmega2560 microcontroller featuring 54 I/Os, 256KB flash, 4KB of SRAM and 4KB of EEPROM. It has standard Arduino header layout extended with tens of additional that are not occupied by shields. They can be successfully used with additional gear.
Previously we have driven servo and DC motor using this simple Arduino motor shield. And we saw how it is easy to interface these motors and write a code. This time we get to real business – stepper motor control. Actually this is what usually motor shields are used for. Stepper motors are more complex devices that require some knowledge. You cannot expect to plug some voltage and see it spinning. Their purpose is stepping, that gives precise control of how much motor is spinning. You can find stepper motor in any printer which feeds paper incrementally – and this is where you can get one. Disk drives is another great source to scavenge. We won’t get in to stepper motor working theory just take a peak on types and working principles before try to run one.
It’s been over three month since solar collector were installed. I decided to build controller by myself. And it turned out that it stayed in prototype stage. So I put it in to enclosure and left it like is. So far it works fine – water is hot everyday, so I have nothing more to expect. I have not many pictures of build, but I think will share what I have. I you have followed forum thread you probably are familiar what system I was building. As I mentioned the solar collector is cheap made in China and is pressureless. Normally they come with special controller which takes care of refilling tank, ensuring protection from water freezing and other special scheduled routines. Pressureless collector usually is first filled with water which heats and then it is used (mixed with cold). Initial test shows that when collector is in direct sun …
Probably you have noticed that Arduino is spread worldwide. It would be ridiculous to see one manufacturer producing them. The Arduino group produces original board that are named Arduino. This is their trademark. But being open source product, Arduino become popular popular in almost all workshops and so demand is huge. Since building plans are open other electronics manufacturers started building Arduino compatible boards. These are same Arduino boards, but with Arduino name and logo removed. Other than that is 100% compatible to standard Arduino that works with software tools, extensions and modules. Arduino compatible Uno R3 Rev3 development board is one of most known boards. Because this form factor is the first Arduino step in to community.
Among my electronics junk I found a VFD (Vacuum Fluorescent Display) display and wanted to make sure it still works and can be used in projects. It’s a 16T202DA1E display manufactured by Samsung. It can replace standard HD44780 based liquid crystal display out of the box. First of all it only requires 5V supply. Voltage step up circuit for lighting fluorescent display is already on board. Controller accepts same commands as any 2×16 LCD does. The pin-out of display is as follows: