I always wanted a spot welder, so I decided to built one. I wanted to build a capacitance discharge one but I couldnt afford for the capacitors at this time. So this is a controller for a dual pulse spot welder with some few extras:
- It has a zero cross detector. You could power the transformer at zero cross or dim the transformer if you like
- The transformer is triac controlled
- It has an hd44780 interface
- An spi interface for single thermocouple
- Peak detector of a current transformer
- Isolated foot switch
- Voltage monitor with opmaps
- An attempt to sense when the user tries to weld
- Single rotary switch for operation and single rotary encoder for setting up
MCU Controlled Spot Welder - [Link]
This project is a 7 segment LED display module that can be driven using SPI protocol, so it needs only 3 pins of your mcu to drive 4 x LED displays. It’s based on MAX7219 LED display driver.
Seven segment LED displays are very popular for displaying numeric information because they are very attractive and readable from a far distance and wider viewing angle.
The downside is they are resource-hungry. For example, it requires 12 I/O pins of a MCU to drive a 4-digit seven segment display using a standard time-division multiplexing technique.
Here I present a serial seven segment LED display module that can be used with any MCU using a 3-wire SPI interface. This particular display has four digits (0.40 size) and two colon segments (to support time display) display.
Serial 4-digit seven segment LED display - [Link]
Exar have announced the 5 mm square SP335 transceiver chip which supports RS-232, RS-485 and RS-422 serial standards. It is a single chip solution between the serial comms port and the UART or MCU allowing system designers to cater for multiple serial protocols over the same connector. The transceiver’s programmable end-of-line termination and multiple configuration modes allow all three protocols to be used interchangeably over the same cabling and connector without the need for additional switching components.
Built in protection tolerates direct shorts to DC or AC voltages as high as ±18 V and severe ESD events. The chip features a separate supply voltage for the logic interface pins, which can be as low as 1.65 V. This allows direct interface with low voltage UARTs and MCUs without the need for level shifters. It also supports data rates up to 20 Mb/s in RS-485/422 modes and 1 Mb/s in RS-232 mode and can be slew limited to 250 kb/s toggling a single control pin. With no inductors or magnetic components, the on-board charge pump generates the RS-232 bipolar voltage levels from a single supply (3.0 to 5.5 V) using just four external capacitors. [via]
Transceiver Chip Handles RS-232, RS-485 and RS-422 - [Link]
Here is a very nice build of a LED heart that creates incredible animations. Check it out.
Today we present the perfect Valentine gadget: just shake it and it will turn on and crate incredible light animations. That will be cool for sure!
We know that, as it’s Valentine’s Day, looking at the device described in this post you’ll be inclined to think that this is the usual heart-shaped Valentine gadget: in reality this is something much cooler as it’s capable to create beautiful and complex light games. Is based on the smallest microcontroller manufactured by Atmel: the ATtiny85.
Hack your Valentine with HeartThrob - [Link]
I present the new module MOD-20.Z Xmega eXploreGO of Modułowo, with the microcontroller ATXmega128A4U and MP3 decoder VS1003B. The module has an DataFlash memory and a microSD card connector. You can connect a Bluetooth module and a radio module nRF24L01. The module can be programmed via USB or programmed/debugged using the connector PDI, derived on the edge of the platform. All signals from the microcontroller are routed to external connectors. Signals connected to VS1003B and DataFlash have SMD jumper and they can be disconnected at any time, in the case of using signals for other purposes. On the edge of the plate also put a small switch ON / OFF for USB power.
The module has two configuration jumpers for selecting the power supply from the USB connector or the VIN. Xmega eXplore GO has a connector’s compatible with the Arduino platform, enabling connection of Arduino shield’s. Microcontrollers ATXmega tolerate voltage +3.3 V, each signal has a built-in resistor with a value of 3.6 kR, allowing you to connect systems +5 V. In some cases they can interfere, so most of the resistors has a SMD jumper on the opposite side. The module is available in two basic versions: with the block VS1003B (MP3 version) and without. A cheaper version will allow the use of the module as a development platform for microcontroller ATXmega128A4U. Below is a picture showing the contents of Xmega eXploreGO.
more info here: XMEGA EXPLOREGO ENG
Xmega eXploreGO – a new module with ATXMEGA mcu and mp3 support - [Link]
By Stephen Evanczuk
For circuits relying on lithium-ion cells, determining the amount of charge remaining in a cell requires specialized techniques that can complicate the design of energy-harvesting applications. Engineers can implement these techniques with MCUs and ADCs normally used in these applications, but at the cost of increased complexity. Instead, engineers can easily add this functionality to existing designs using dedicated “fuel-gauge” ICs available from manufacturers including Linear Technology, Maxim Integrated, STMicroelectronics, and Texas Instruments.
Determining the state of charge (SOC) in lithium-ion batteries is essential yet challenging due to the great variability in capacity not only across different cells, but also in the same cell. As a Li-ion cell ages, it loses its ability to store charge. Consequently, even if fully charged, an older cell would deliver usable voltage for a shorter period of time than a newer cell. With any Li-ion cell, SOC varies greatly depending on the temperature and discharge rate, resulting in a unique family of curves for any particular cell (Figure 1).
Fuel-Gauge ICs Simplify Li-Ion Cell Charge Monitoring - [Link]
bogdan @ electrobob.com wanted to know how much heat a heatsink can dissipate so he build a simple setup using a temperature sesnsor and a mcu. He writes:
It’s quite a common problem when building electronics that some components need cooling which is usually done through some sort of heatsink and optional fans. Choosing the right cooling solution can be a difficult task because the real life behavior of the system is hard to predict or model. In my case I have faced the simple question quite a few times: how much heat can a cooling system dissipate? The thermal resistance of a particular heatsink may vary quite a lot depending on the surroundings or it can simply be unknown to start with. The aluminum side wall of an enclosure made me build this thing.
This is why I have made this little device: a thermometer, a transistor and a microcontroller with a simple command line interface. I could have answered my questions in quite a lot of simpler ways, but since I made a simple thermometer not much else is needed to control the transistor when a DAC is available in the microcontroller.
Heatsink Tester - [Link]
It consists of a power supply, the basic components for running the microcontroller (i.e. crystal, reset pin, …) and ICSP connector for In-Circuit programming. All pins are available on a header strip, so it is ideal for rapid prototyping.
PIC16F/18F Experiment Board - [Link]
Raj @ embedded-lab.com build a mini LED Christmas tree for his son. He writes:
My two and a half year old son loves toys with flashing lights. For this Christmas I thought of making a mini LED Christmas tree for him. This project uses 22 multi-color LEDs which are driven by a PIC12F683 microcontroller using the Charlieplexing technique. The details of the build procedure is described in the following sections.
Making a mini LED Christmas tree - [Link]
Embedded Lab’s new development board for PIC12F series microcontrollers:
The 12F series of PIC microcontrollers are handy little 8-pin devices designed for small embedded applications that do not require too many I/O resources, and where small size is advantageous. These applications include a wide range of everyday products such as hair dryers, electric toothbrushes, rice cookers, vacuum cleaners, coffee makers, and blenders. Despite their small size, the PIC12F series microcontrollers offer many advanced features including wide operating voltage, internal programmable oscillator, 4 channels of 10-bit ADC, on-board EEPROM memory, on-chip voltage reference, multiple communication peripherals (UART, SPI, and I2C), PWM, and more. Today we are introducing a new development board (rapidPIC-08 V1.0) for easy and rapid prototyping of standalone applications using PIC12F microcontrollers.
Rapid development board for PIC12F series microcontrollers - [Link]