The old resistor decade boxes consisted of a bunch of rotary switches which make them little bulky and expensive. Stynus has built this microcontroller-based resistor decade box that uses one rotary encoder and 16 relay switches to switch on the various resistances. The microcontroller used in this project is PIC16F84A.
PIC Microcontroller based resistor decade box - [Link]
An instructables on motor controllers for cheap robots by JayWeeks
Almost every robot needs to power a motor of some sort or another. Problem is that motors take quite a lot of power, compared to what most microcontrollers operate with. To solve this problem, robots use what is called a motor controller, which usually amounts to some form of electronic switch that can turn on a very high voltage, using a very low one. That’s what we’ll be making today!
Motor controllers for cheap robots - [Link]
xristost blogged about the frequency counter module he made:
First of all I wanted a PIC microcontroller to do the whole job without any additional ICs. Also I wanted to use the the familiar 16F628A, but because one of the portA pins (RA5) can be used only as input I was short of outputs to do the job. Driving 6 digit 7-segment multiplexed display requires 7 + 6 = 13 outputs. The 16F628A has 16 IO pins, two of which are used for the crystal oscillator, one is for the signal input and other one can be used only for input, that leaves us with only 12 useful IO pins. The solution was to drive one of the common cathodes with a transistor, which opens when all other digits are switched off.
Frequency counter with PIC16F628A - [Link]
A fine-spot welder is one of the few equipment where building yourself is cheaper than buying. There are already published a lot of DIY spot welders, this one has some unique features:
It can be used in 2 welding applications: opposed and series configuration.
The construction is kept very simple.
Accurate electrode force adjustment.
It has a solid electrode holder, made of a radiator earthing clamp.
An Arduino microcontroller is used to set the weld time accurately.
Creates a double pulse which improves clamping.
The current can be reduced for welding sensitive parts.
DIY battery tab resistance fine-spot welder - [Link]
An inexpensive single board computer which connects to a composite video monitor, keyboard, and SD card by Jack Eisenmann:
I created the DUO Light as a low cost platform for hobbyists to create fun and useful software. The DUO Light is ideal for anyone who wants a low power computer with video output and keyboard input.
The DUO Light is a hybrid of the Arduino UNO and the Raspberry Pi, but costs less than each. At the heart of the DUO Light is the ATMega328, the same microcontroller as in the Arduino UNO. This chip connects to a variety of peripheral devices, including a composite video monitor and SD card (in a similar fashion to the Raspberry Pi), PS/2 keyboard, and general purpose I/O ports. The second chip onboard is a 64 KB serial SRAM, which also connects to the ATMega328.
DUO Light Computer - [Link]
Davide Gironi writes:
DS18B20 is a programmable resolution 1-wire digital thermometer.
It has an operating temperature range of -55°C to +125°C and is accurate to ±0.5°C over the range of -10°C to +85°C.
This library is an AVR implementation to retrive temperature from DS18B20.
Built using the reference document: “Using DS18B20 digital temperature sensor on AVR microcontrollers” by Gerard Marull Paretas, 2007.
A DS18B20 1-wire digital thermometer AVR ATmega library - [Link]
by Vadim Panov:
Back when I was only starting to dabble in electronics, I needed a project that would meet the following requirements:
simple to make;
original (i.e. done entirely by myself from scratch);
containing a microcontroller;
and maybe the most important of all, useful. I’ve had enough devices I assembled just to dismantle the whole thing a month later.
The thing I came up with at the time was a light swich for my room controlled over an IR remote from TV. Remote that I had used RC-5 protocol, hence the firmware is suited for any RC-5 compatible remote.
Everyone is familiar to the everliving problem with switching the lights off in your room before going to bed and stumbling back across the room. The IR switch I describe here solves that problem, and I can definitely tell that this project was a success – I am still using it with no regret.
Infrared remote controlled light switch with ATTiny2313 - [Link]
Embedded modules may surprise you by their contribution and an overall costs savings.
As we know „embedded module“ is a quite wide term and it can represent a powerful microcomputer with OS, but it can also be a significantly simpler module with a microcontroller and peripherals, still able to add considerable functionality to a target device.
Typical representatives of useful modules, which add a lot – without big costs are so called quick start modules from company Embedded Artists. Their contribution is in a ready-made „tuned up“ PCB containing for example in case of module LPC4088 QuickStart Board (EA-QSB-016) the microcontroller itself (Cortex- M4), memory, display controller and many interfaces like Ethernet, USB, UART, SPI, CAN, PWM, Analog In/Out, I2C, XBee compatible connector and other.
Especially at low and mid-volume production batches their contribution is mainly in the fact, that it is a really proven solution with a guaranteed operating temperatures range, proper ESD protection and mainly – supported by a wide scale of development tools (free). In case of solving of problems, it´s still possible to contact customer support of company and a lot of hints for successful usage, source codes and libraries can be found directly on the producer´s website.
Try to go easier way - [Link]
herpderp shares his waveform generator:
Here is my last project, a tiny waveform generator based on my previous project and some components:
– An AD9834 (DDS chip with sinus/triangle output)
– 2 x AD5310 (10bit DAC: one for the Vpp control, another one the offset control)
– 3 x LM7171 (Fast OPA)
– 3 x LT1616 (switching regulator: +5V, +7V, -7V)
This waveform generator is directly powered by a standard 12V jack and is capable of outputting a 10Vpp signal at 1MHz (between -5V and +5V, sinus waveform, no load). Above 1MHz, the output starts fading, reaching only 9Vpp at 4MHz (maximal frequency). Frequency, amplitude and offset are digitally controlled through the smart TFT.
Three “basic” waveforms are provided: sinus and triangle, coming from the DDS chip (0.1Hz to 4MHz, 0.1Hz step), and PWM coming from the microcontroller (0.1Hz to 1MHz, variable steps).
Tiny waveform generator - [Link]
An interesting open source NFC project is seeking for funding on kickstarter.
MicroNFCBoard is an integrated development platform that makes it easy to use Near Field Communication or NFC (What is NFC? see below for more info). It contains a NFC transceiver, a microcontroller and all the software you need to use NFC.
It can be used with an Arduino, Raspberry Pi, mbed or PC/Mac. There is also a powerful ARM Cortex-M0 microcontroller onboard so it can work on its own and you can connect a bunch of things to the board using its various peripherals.
MicroNFCBoard – Easy NFC for the Internet of Things - [Link]