Circuit-Zone.com - Electronic Projects

Thermostat Controller with LCD
Posted on Monday, July 18, 2011   •   Category: AVR

Thermostat Controller with LCD

I wanted to share my project of modifying the temperature sensor project and turning it into a thermostat with ATmega168. I added a digital output to drive an LED to "warm" the temperature sensor when the current (actual) temperature falls below the desired temperature. Two push buttons come in as digital inputs one to ramp the desired temperature up and the other to ramp it down. The logic is simple bang-bang control to turn the LED on and off based on the relationship of actual temperature to desired temperature. It simulates a thermostat in heater mode. The LED is off when the current temperature is above the desired temperature and turns on once the current temperature falls below.

Radio Receiver Circuit
Posted on Monday, July 18, 2011   •   Category: FM Radio / Receivers

Radio Receiver Circuit

This radio works with solar batteries that provide voltages between 0.5 and 2V. Microphones should be magnetic, high impedance (2k or more). The coil is wrapped around a ferrite rod 1 cm in diameter with 28AWG wire.

Character LCD Displays
Posted on Monday, July 18, 2011   •   Category: Miscellaneous

Character LCD Displays

LCD character displays can be found in espresso machines, laser printers, children’s toys and maybe even the odd toaster. The Hitachi HD44780 controller has become an industry standard for these types of displays. This tutorial will teach you the basics of interfacing with a HD44780 compatible display using some DIP switches and a few other components.

USB AVR Programmer
Posted on Saturday, July 16, 2011   •   Category: AVR

USB AVR Programmer

USB AVR Programmer for Atmel AVR microcontrollers. USB AVR Programmer is made of an Atmega8 and few components. The programmer uses a firmware driver that makes this programmer attractive to many amateurs. Another thin why this programmer is so popular is because it is officially included and supported in WinAVR. Once again lets see what this programmer is made off and how to set it up. The core of USB AVR Programmer adapter is Atmega8 microcontroller clocked by 12MHz crystal. Soldered board is ready to be connected via simple USB cable with B type connector (Computer side needs A type of connector). Resistors R2 and R6 are current limiting resistors, that protect computer USB port. Resistor R7 helps computer to recognize device as LS (Low Speed). Diodes D1 and D2 indicates about data transfer. Header SV1 is compatible with STK200/300 just 4 and 6 pins are used for RXD and TXD (may be used for other purposes).

Adjustable Bench Power Supply
Posted on Friday, July 15, 2011   •   Category: Power Supplies

Adjustable Bench Power Supply

I’ve built myself my own universal, adjustable bench power supply. This isn’t strictly astro stuff but the main reason I built it is to experiment with TFT backlight panels that I use for my lightboxes. I needed 5V and 12V to play around with the inverter boards and figure out their pin-out. I considered buying a bench power supply. But prices were too high, especially for ones with adjustable voltages. So I decided to build my own. This one has 4 outputs. One 5Volt, one 12V and two individually adjustable outputs going from about 1.5V to 19.5V. Each can draw up to 1.5Amp with a total of 3.5A for all together. The input is a standard replacement laptop power supply 20V, 3.5A. With a stronger external power supply the total output current can be higher, up to 1.5A per output. But currently the 3.5A is more than enough. Each of the adjustable outputs has its own little voltmeter built in. The fixed voltage regulators are based on a 7805 for the 5V and a 7812 for 12V. The two adjustable regulators are based on one LM317 each.

28W FM Broadcast Transmitter Amplifier 88-108 MHz
Posted on Friday, July 15, 2011   •   Category: FM Transmitters

28W FM Broadcast Transmitter Amplifier 88-108 MHz

This RF Amplifier designed for FM broadcast using a single 2SC1946 VHF Power Transistor. This 10-30W RF amplifier circuit provides an appropriate power boost with an input of 1-3 watt. Tower are 30 meters high will send signal surrounding air should be around 15 km. The layout of the 2SC1946 28 Watts FM broadcast RF amplifier has been created with Eagle. The pcb outline is 100 x 50 mm (width x height), all bitmaps have a resolution of 600dpi.Use FR-4 single sided photoresist epoxy pcb material for best results.

Digital Barometer with Graphical LCD Display
Posted on Thursday, July 14, 2011   •   Category: PIC

Digital Barometer with Graphical LCD Display

Here's a digital barometer that uses Atmega8 microcontroller and graphical LCD display. This project uses SCP barometer pressure sensor graphical LCD display connected to Atmega8 microcontroller. Graphical LCD displays latest 128 readings while one reading occur once in 20 minutes. You can see information of about two last days. Provided C source code can be customized to your liking.

PIC Temperature Logger
Posted on Thursday, July 14, 2011   •   Category: PIC

PIC Temperature Logger

This project uses a Microchip PIC microcontroller, a serial EEPROM and a thermistor to create a temperature recorder. The temperature is measured and stored at user programmable intervals; this can be from 1 second to 256 seconds. The time interval is set by programming it and the start time into the EEPROM. Most of the time the PIC will be asleep and the EEPROM IC is inactive. This gives a very low current consumption of approximately 50 uA or about 1 mAh per day. The EEPROM used is 32kBytes which can store up to 32,000 measurements. This could be one measurement every 30 seconds for 11 days for example. The combination of thermistor and analogue circuit gives a range of between about -40 °C and +100 °C although the linear range is between about -10 °C and +40 °C.

5 Watt Transmitter
Posted on Thursday, July 14, 2011   •   Category: FM Transmitters

5 Watt Transmitter

This is a very simple 5 watt CW TX based upon a TTL logic chip. There is just one "tricky" component and this is Cx. This component should have an impedance of about 10 - 50 ohms at the frequency of interest. If you wish to reduce the transmitter power, increase the value of Cx. It is Cx which causes the square wave from the output transistor to approximate a sine waveform. The value of Cx is the price of simplicity in this TX.

Automatic Battery Charger
Posted on Wednesday, July 13, 2011   •   Category: Battery Chargers

Automatic Battery Charger

Automatic battery charger automatically starts the charging procedure when battery voltage drops below a certain predefined value and stops after the voltage has risen above the maximum allowed value. Setup can't be easier, just connect two alligator clips to battery terminals and plug the device in mains. This way it can stay connected for months and the battery will never overcharge. This comes very very handy when you have a scooter or a real motorcycle that you don't drive during the winter time. Because we all know what happens to a battery when not used and especially during the winter.

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