Vacuum Tubes Valves
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AC to DC & DC to DC
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Switching Power Supplies
Light Laser LED
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Data Bus Circuits
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RF Converter Circuits
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voltage to frequency
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TV Video Circuits
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8051 / 8052
PCB CAD Software
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555 Timer Circuits
Remote Control Toy
H Bridge Circuit
DIY HV Variable Cap
DIY PMA alternator
Interconnection & Timing
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4 Band Resistor
5 Band resistor
6 Band resistor
PIC Microcontroller Circuits
PIC Microcontroller Circuits
Dual Channel Servo Pulse to H-Bridge Interface
The interface uses a PIC16F876 microcontroller and not much else. It performs channel mixing, current limiting, and noise rejection. Push the stick forward, both motors move forward, move the stick to the left and the robot moves left. It makes the robot very driveable. You can use a wheel transmitter meant for cars to control it, in other...
PWM fan controller
Microchip Technology (www.microchip.com) offers a family of cooling-fan speed controllers that operate in PWM mode for use with brushless dc fans (Reference 1). To control fan speed using the PWM waveform`s duty cycle, you can use either an external NTC (negative-temperature-coefficient) thermistor or one of Microchip`s PIC microcontrollers and...
SMBus Fan Speed Controller
Battery run times for notebook computers and other portable devices can be improved and acoustic noise reduced by using Linear Technologys LTC®1695 to optimize the operation of these products internal cooling fans. The LTC1695 comes in a SOT-23 package and provides all the functions necessary for a system controller or microcontroller to...
RS485-like multi-drop bus
PBUS is an RS485-like multi-drop bus for interconnecting PIC and other microcontroller-driven devices. Protocol and software is written by Jap. Just include a separate pbus library file into your project and add your command handlers for the specific device in a few lines.
LCD Serial Terminal
This project is a self-contained serial terminal using a PIC16F84 microcontroller chip, an inexpensive LCD character display, a keypad, and very little else. It is full-duplex, meaning keypresses cause RS-232 output, and RS-232 input makes characters appear on the LCD. If you connect the RS-232 output to the input you can see the keys as you...
Low-power keypad 100 nA
The circuit in Figure 1 is a keypad interface that solves this problem by using an ultralow-power microcontroller. The circuit typically consumes 100 nA while awaiting a key press and consumes a maximum of only 2 µA if all keys are stuck or held down. An added bonus of the circuit is that it requires no crystal.
PIC16C5x Microcontrollers as LCD Drivers
The Liquid Crystal Display (LCD) is a thin layer of Liquid Crystal Material deposited between two plates of glass. The raw LCD is often referred to as glass. Electrodes are attached to both sides of the glass. One side is referred to as common or backplane, while the other side is referred to as segment.
Mobile MP3 Player PC
The CPU is an AMD K5 running 75 MHz. Theres 16 meg ram, and the operating system is Linux (Red Hat 5.2). MPG123 handles the MP3 decoding, and I wrote a control program in Perl. I built the remote control in an old Blaupunkt CD-changer remote case which I emptied completely. It now has a backlit 40x2 LCD and a PIC 16F84 microcontroller. It...
A PIC16F84 based CW Decoder
I propose a simple CW decoder wich makes use of a PIC16F84 microprocessor with a 16x2 chars LCD display. It is equipped with an audio frequency input from your receiver, an input for a stright key and an audio output locked to the input signal. It automatically adapts itself to the CW rate and may be employed for learning purpose substituting...
Robot Beacon is a rotating light. We have called it Robot Beacon as it has been designed as an addition for a robot, but it can be used for many applications. It can be used as a mast-head beacon on a boat or as an "all-round" warning light on a bike. Robot Beacon uses a PIC12C508A OTP (One Time Programmable) 8-pin microcontroller.
Saving the OSCCAL value for PIC 12F629 / 12F675
The PIC 12F629 and 12F675 have a factory set oscillator calibration value written to the last program memory location during manufacture. When programming the PIC the programmer software should read this value out, merge it with the program data being written to the PIC, and then write it back.
RGB PWM Driver for 350mA LEDs
# This version uses a double sided PCB. Dimensions are approximately the same as the original version. # Removed the second push button switch and components for the RS232 serial interface. # Added 22K resistor between MCLR input and Vdd. This eliminates the need for a jumper on the ICSP header in normal operation. (If you use a...
4 Channel DMX512 Driver
This project is a 4 channel DMX512 driver board. It features four power MOSFETs that can be configured to operate in PWM mode or as on/off outputs. The driver can be configured to use any four consecutive addresses across the full 512 channel address range. It can be used to drive LED arrays or low voltage lamps in PWM mode or operate relays...
MOSFET RGB LED PWM Driver
The RGB LED driver described on this page uses logic level 'N' channel MOSFETs which allow it to control LED arrays or lamps at up to 5 amps per channel without heatsinks. The driver uses exactly the same firmware as the small RGB LED driver shown in the photo so you can use the same code and sequences with this board to control big arrays...
RGB LED PWM Driver
The circuit uses (RGB) Red, Green and Blue high brightness LEDs that are pulse width modulated (PWM) to vary the intensity of each colour LED. This allows effectively any colour to be generated with rapid changing strobe effects, fast and slow colour fades as well as static colours. The data used to set and change the colours is held in an...
PWM DC Motor Controller PIC 12F683
A variable resistor provides a voltage input to the PIC which is converted to a digital value using the onboard Analogue to Digital convertor, this in turn is used to set the PWM duty cycle. Since the PWM duty cycle is adjusted using a voltage signal input to the PIC it is possible to use an alternative analogue front-end instead of VR1 to...
8 Channel PWM LED Chaser PIC 16F628A
This neat little circuit provides 8 LEDs directly driven from the PIC along with a single mode control switch. The firmware elsewhere on this page drives the LEDs with a 5 bit PWM signal providing each of the 8 LED channels with four levels of intensity; off, dim, mid, bright. A number of sequences are programmed into the firmware to provide...
LED Chaser with PIC16F84A / 16F628A
This simple circuit functions as a 12 LED chaser. A single illuminated LED 'walks' left and right in a repeating sequence, similar to the effect seen on KITT, the car in the Knight Rider TV series. Fully commented source code and programmer ready HEX files are provided for the PIC 16F84A and 16F628A at the bottom of this page. The circuit...
Recalibration Utility Oscillator
The PIC 12F629 and 12F675 devices have an internal 4Mhz oscillator that enables the devices to be used without an external crystal or RC network. This frees up one or two pins for I/O use and allows the device to be built into minimum component count designs. The internal oscillator needs to be calibrated and this is achieved by reading a...
Astable Timer with PIC 12F629 / 12F675
This software functions as a long period astable mutivibrator. The mark and space period can be set from 1 second up to a maximum 65535 seconds (18h12m15s). Using the internal 4Mhz RC oscillator delays with an accuracy of 99% or better can be achieved The code also implements an edge triggered reset and an active low hold function. The...
4-digit Up/Down counter with PIC 16F88
This is a 4 digit decimal counter which can operate as a free running counter or in count and hold mode with manual reset. In either mode the counter can be preset to count to a specified value. Clock edge and leading zero suppression can also be configured. The 7-segment display and indicator LEDs are multiplexed. It will drive most...
PIC to RS232 Interface
The circuit shown will convert logic level voltages to and from RS232 serial voltages levels. For basic serial comms between a Microchip PIC and a PC or other device you generally only need to connect the Gnd, Txd and Rxd lines. This little circuit will work with a supply voltage of 3.3v to 5v making it ideal for interfacing with a PIC
Voltage programmable square wave generator
Here's another daft yet interesting PIC12F675 idea I came up with. When I wanted to show someone how logic gates worked I could only find a NAND gate which wasn't very handy for demonstrating AND's OR's, NOR's and ExOR's. I also wanted to have a play with the A/D converter on the 12F675 so I came up with the idea of a PIC that could function as...
Race Start Lights
This project provides an simple F1 motor racing style 5 light race start sequence with a random delay that you can use on a real race track, kart circuit or even your slot-car circuit. Operation is simple; when the start button is pressed all the LED clusters are off. They then illuminate sequentially at one second intervals until all five...
Interfacing Relay To Microcontroller
Relays are devices which allow low power circuits to switch a relatively high Current/Voltage ON/OFF. For a relay to operate a suitable pull-in & holding current should be passed through its coil. Generally relay coils are designed to operate from a particular voltage often its 5V or 12V. The function of relay driver circuit is to provide the...
5W PLL FM Transmitter (PIC16F627A)
The transmitter includes RDS/SCA input and Audio/MPX input with optional preemphasis. It can be used with or without stereo encoder. Tuning over the FM band is provided by two buttons that control dual-speed PLL. The transmitter can work also without the LCD display. Some experience with building devices of this kind are highly recommended....
Frequency counter 400Hz to 50MHz with PIC 16F84
It consists only from Microchip PIC 16F84 cpu and LCD text module. Author states that this counter is capable metering frequencies from 400Hz to 50MHz. I used faster, 20MHz version of 16F84A-20I/P, and it managed to count 80MHz oscillator output.
Diode tester using PIC 16F84
This is a simple use of the PIC 16F84 about a diode tester. Test procedure : We set «1» to PB0 and «0» to PB3. If diode is ok and opens, then at PA0 we have «1». If PA0 is «0», then the the diode has problem. With the program we manage what the PIC will do in each situation . If PA0 is «1», green led lights wich means that the diode is OK and...
Aquarium Auto Controller using PIC18F4520
The AquaCont is an electronic system witch permits to manage and to monitor most of the parameters of all the electrics devices that can be found in a aquarium. The PIC18F4520 used to realize it, combines a real time clock and a temperature sensor in order to control 8 relays. The LCD display permits to monitor the current date and time, the...
OSCCAL Value Finder Board with 16F88
The program loaded in the 12F675 device which has no osccal value will force a pulse on GPIO.4 and it will make a loop while increasing the osccal value internally. GPIO.5 will send the current osccal value used for each pulse sent. Because the device has no calibrated osccal value, the pulse will be variable. The circuit will wait until it...
one wire keypad with PIC16F88
This project can be used for many different purposes. Probably the most used application would be to interface to any electronic project that requires a keypad. There are several ready made keypads on the market, but those work with matrix connections and require 7 pins for a 12 button pad. For new programmers, matrix keypads can be a bit tricky...
Digital clock with thermometer and hygrometer
I use a RealTimeClock Maxim DS1305. The RTC backup power is a supercapacitor (0,22F). I test it for 4 weeks, works fine. For this reason it don't have the capability to change the time, but you can do small-corrections. Once you push the button, the seconds change to 30, with no effect to minutes, hours etc. The routine is in lines 1878-1887...
Arduino Projects and Circuits
AVR Microcontroller Circuits
Microcontroller Programmer Circuits
68HC11 Microcontroller Circuits
8051 / 8052 Microcontroller Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity