Charging lead acid car is fairly simple. You need to take care of charging current which should be around 0.1C and charge up to 13.4V battery voltage. Having this in mind, it is easy to build charger out of few parts available. Pityukecske have shared his version of battery charger on instructable. He has chosen a PIC12F683 microcontroller which controls relay switching charging current to battery and also monitors battery voltage on one of its ADC inputs.
Current circuit doesn’t have much flexibility – charging current is basically driven directly from transformer and diode rectifier. It is visible on panel ammeter. So transformer is chosen to meet current requirements. Microcontroller monitors battery voltage. Since it is over 12V there is a resistor voltage divider used to scale voltage to microcontroller working limits. Once voltage reaches 13.4V, microcontroller shuts current by deactivating relay. Couple status LEDs indicate charging state. Simple solution that works in most cases.
PIC12F are great small microcontrollers with 8 legs. They usually come with internal oscillator, 4 channels 10-bit ADC, EEPROM, voltage reference, several communication peripherals like USART, SPI, I2C, timers and other. So with it you can build quit powerful applications and control devices.
Embedded-lab introduced pretty handy development board fir this micro. It has many features that enable rapid prototyping or learning the basics. It comes with 5V voltage regulator, I/O header for all MCU pins, fairly big prototyping area, ICSP programming header, four push buttons connected to analog pin through voltage divider resistors, and couple LEDs – one power another attached to digital output. You can solder any component to prototyping area and have even more to do.
Pong game is one of the first arcade games ever created. It mimic tennis game and is super simple. DysfuncTech couldn’t let it go and built Pong game on PIC12F1840 8-pin microcontrolller. It can be connected to TV and played as it was times ago. Game resolution is set to 32×56. It cant get higher due to RAM limitations. And there is no need for more res as game is simple as two cents.
With some code optimizations he was able to squeeze in sound. It is played using piezo speaker. If you look at build log you’ll see that project has several releases with better improvements every time. Right now it looks pretty polished for having great experience.
A clap switch could be nice addition inside the house. And it may be really practical when reaching for light switch in the dark – just clap your hands couple times and light goes on. Embedded-lab discusses on how to build a simple clap switch using few widely accessible components.
Obviously first part is capturing sound using microphone. Its signal is boosted using transistor amplifier. After signal level is raised to match microcontroller input levels it is captured by PIC12F683 microcontroller. Analog comparator inside MCU makes things much easier as it allows comparing two analog voltages and decided when clap has occurred. Simple microcontroller program simply listens for two claps in a row and toggles output LED which can be easily replaced with relay switching heavier loads.