Hemal Chevli blogged about his transistor tester project:
It has mega-8 as the brain, lcd to show specs of the transistor like which pin is which, what type of transistor it is eg NPN,PNP, N-MOSFET,P-MOSFET, etc., many components can be tested like different types of transistor, diodes, resistors etc, the good thing about this is that it also shows which leg is which, no need to open the data sheet
Transistor tester project - [Link]
Scott Harden writes:
In an effort to resume previous work [A, B, C, D] on developing a crystal oven for radio frequency transmitter / receiver stabilization purposes, the first step for me was to create a device to accurately measure and log temperature. I did this with common, cheap components, and the output is saved to the computer (over 1,000 readings a second). Briefly, I use a LM335 precision temperature sensor ($0.70 on mouser) which outputs voltage with respect to temperature.
Precision temperature measurement - [Link]
Hercules Trapierakis writes:
This is a copy paste tool of George’s Homemade Soldering Station but with some improvements and not with a PIC but with an AVR ATMEGA8 uC. I have changed the way that the information is displayed also you can adjust the P I D values and it has a safe mode option – that it will turn off the soldering iron if it is not used for a certain amount of time.
Homemade Soldering Station - [Link]
This is a simple use of internal ADC of AVR atmega8. Voltage is measured directly with help of resistor divider and amperes is calculated based on the voltage drop in a low resistance power resistor.
Atmega8 based Volt – Ampere meter - [Link]
Charalampos Andrianakis writes:
Two years ago i modified a scanner replacing its mechanism and all the internal electronics with UV lamps converting it to an UV exposure box for PCB prototyping. By the need of making my life easier and not waiting for the pcb to be exposured i designed an AVR timer to automatic switch off the lamps after 1 minute of exposure which was much enough for the PCBs. Here is the circuit
This was one of my first completed projects from design to production. As you can see the scheme isn’t that good and there have been by passed some capacitors at the power supply. But the circuit works with no problem.
AVR Switch Timer - [Link]
I designed this version in the need of a thermometer for my room, built in a small pack and easy to control. The hardware is designed on a way so that the pcb can be wall mounted. At the top side of the device the PCB extents giving space for two keyhole type holes which are able to keep the device mounted on the wall. The LCD display plugs at the front side of the PCB, covering all the electronic components and giving a compact design view. The user can interact with the device using the left side switch button. The design includes a 6-pin header which gives connectivity for UART (RX,TX,GND) and for the external sensor DHT-11 (VCC,GND,DATA). Also there is an ISP-6 pin header which gives the option of on board programming. Finally there is an optional Bluetooth plug on the back side connected with AVRs UART for possible communication to other devices like mobile phones, home automation devices, pc’s or whatever you imagine.
The code is written in C and is well performed in a readable way so anybody can read and modify it. For the LCD driving i have used Peter Fleury’s library.
AVR Atmega8 and DHT-11 Thermometer V2.0 - [Link]
After our recent post about the commercial semi-conductor tester we started a discussion about building a similar open source project. What came up is this AVR based transistor tester (machine translation) by Markus.
It’s built around an ATmega8 IC that interfaces with a standard HD44780 16×2 character LCD. The circuit that does the testing is simplicity itself. Three pairs of resistors are connected to 6 pins of the microcontroller, and each pair is connected on the other end to one of the transistor pins.
The theory of operation is also relatively simple. The microcontroller cycles through different patterns on its output pins until a recognizable pattern is read on its input pins. It supports a very large range of devices:
- NPN and PNP bipolar junction transistors.
- P and N channel, enhanced and D type mosfet transistors.
- P and N channel JFET transistors.
- Common anode and common cathode dual diodes.
- Two diodes in connected in anti-parallel or series configuration.
- Single diode.
AVR-based transitor tester - [Link]
USBasp is a USB in-circuit programmer for Atmel AVR controllers. It simply consists of an ATMega48 and ATMega88 an ATMega8 and a couple of passive components. The programmer uses a firmware-only USB driver, no special USB controller is needed.
- Works under multiple platforms. Linux, Mac OS X and Windows are tested.
- No special controllers or smd components are needed.
- Programming speed is up to 5kBytes/sec.
- SCK option to support targets with low clock speed (< 1,5MHz).
USBasp – USB programmer for Atmel AVR controllers - [Link]
PocketBot – a matchbox-sized line following robot – [via]
PocketBot project consists of three parts. The key part of the project is the robot itself – a tiny line following vehicle of a matchbox size. Furthermore, the robot is supported with an USB communication device and with a PC control application. Altogether, these three parts form a complex solution to the line following issue.
The robot was primary designed to fit into a matchbox. A homemade double-sided printed circuit board stands as the robot’s chassis at the same time. Robot is powered with two rechargeable lithium-ion button batteries wired in parallel (3.6V, 40mAh each). The Atmel ATmega8 microcontroller runs robot’s program, which is written in C. An 8-pin connector offers ISP and UART interface for programming and debugging, respectively.
PocketBot – a matchbox-sized line following robot - [Link]
Shawon Shahryiar (from Bangladesh) describes in this project about the HSM-20G sensor and its interfacing with the Atmega8 for measuring the ambient temperature and relative humidity. HSM-20G is an analog sensor that converts the ambient temperature and relative humidity into standard output voltages which can be measured through the ADC channels of Atmega8. With the use of the calibration curve provided in the datasheet, these analog voltages can be converted back to the temperature and relative humidity.
Atmega8 + HSM-20G to measure the relative humidity and temperature - [Link]