Top Circuits Page 246
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The antenna used for either receiving or transmitting is a vital element in the communication link. In most cases the antenna has a great deal to do with how well the receiver or transmitter works. Antennas are reciprocal, meaning that an antenna designed....
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I built one of these with the RS-232 option many decades ago. It a three channel HF receiver (5, 10 & 15 MHz) that receives either the U. S. or Hawaii WWVH time and frequency broadcasts and displays the time to a tenth of a second. It also has a discipline....
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BR Communications (later merged with TCI to become TCI/BR, later bought by Dielectric Inc ) makes a line of chirp sounder transmitters and receivers. See my RCS-5 Chirp Sounder page for more on this. One of the features of the Chirp Sounder system is that a....
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This page describes the construction of an electric field mill. This is a device to measure the electric field strength on earth due to the static electric field and the charge of clouds passing overhead. It can also be used to investigate static electricity....
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Condenser Microphones typically sound better than dynamic microphones. If you are unfamiliar with these two types of microphones you may want to read about them in this Wikipedia article. Electret condenser microphones have to little plates (capacitor), one....
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Driving an LED, we covered the electronic theory of how to use a Power MOSFET to turn the LED On and Off via a digital signal. In this post, we are going to walk the reader step-by-step on how to wire-up the circuit on a breadboard. The Bread board is an....
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Timed precisely with the pistons` pumping, this component works with the ignition coil to create the voltage jump that causes the spark in the spark plug. Engine Cut Out Switch - Essentially an emergency button, when pressed, this provides a route to ground....
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Capacitor Discharge firing boxes are well suited to certain types of electric match ignition and ill suited for others. Experimenting with this technology can be fun and educational, but the cost of a commercial CD firing box can be prohibitive. CD circuits....
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Sun tracking systems are very effective in increasing the efficiency of photovoltaic (PV) arrays, and are essential for concentration PV systems. The following paper discusses a light tracking servo model which has been built to simulate the movement of a PV....
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Triple check your pins on the datasheets for your chips and make changes if you need to. In my case, The RAM chip I used had a non-inverted enable on pin26, but the schematic assumed the enable was inverted. This caused the circuit not to work until I....
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The goal of the project is to create a robot that will follow a black line on a white sheet of paper and solve a maze created out of those materials. The project also included a list of specifications that were to be followed. These specifications are: The....
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A cheap garland tree and fill it full of blinking LEDs. The tree shown is a cheap garland wrapped plastic frame from Walmart. It could easily be made, but I didn`t feel like taking the time to do so. Besides, I got in on clearance, so I might not have been....
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This tutorial continues on from ATmega8 Breadboard Circuit Part 1 where we build a small power supply on the breadboard. In this part we will add the ATmega8 microcontroller and an interface to allow it to be programmed. The first step is to orient yourself....
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Interfacing with a HD44780 compatible display using some DIP switches and a few other components. The module that we are using is a 16 character x 2 line display that we stock over here. It uses an ST7065C controller, which is HD44780 compatible. The figure....
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EEPROM (Electrically Erasable Programmable Read Only Memory) Is non-volatile memory, meaning it persists after power is removed. The ATmega168 microcontroller has 512 bytes of EEPROM which can be used to store system parameters and small amounts of data.....
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Build a 10W LED flashlight that features swappable UV/IR/visible heads. We decided to document the build since this flashlight would fit nicely in a photographer`s kit for light painting, IR illumination, UV reflected photography, or UV fluorescence....
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Vacuum tube tesla coils operate in a continuous wave mode of operation, continuously providing energy to the tesla coil secondary. As a result, the output is primarily determined by how much power the vacuum tube can process. The spark discharge and....
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The Mini AV Test Box circuit is as simple and straight forward as I could design. It has three main sections that I split up in the schematic. The main devices used in the circuit are the 7805 +5v Regulator, 16F84A Microcontroller and 555 Timer. This is a....
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The first schematic that we`ll look at is the base schematic of the transmitter without any modification. The RC car`s transmitter circuit has two halves to it. One side (on the left) is pretty much all digital. When a switch(1-4) is pressed, IC1 becomes....
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The schematic for this project isn`t too, too bad to look at even though it`s not the best drawing/layout for a schematic that I`ve ever done. The basic flow is from left to right. Left side is the state machine, then the 555 timers, then counter circuitry....
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Here is the circuit for the FM Bug. In total there are 18 core components that are needed for the fm transmitter to work properly. The far left side has the electret microphone and then things move electrically to the right until they hit the antenna. Don`t....
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The schematic for this project is much more complicated than previous projects. There are four main features in our design. (1) We will be able to program the pic on the board we develop. (2) We will be controlling a servo. (3) We will be taking data input....
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The full schematic for this project is really, really big so if you want to see it, go ahead and click the picture below. Since the schematic is so big I split the explanation of how things are connected together into three sections. The Hsync Generator,....
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The IR Theremin hardware schematic is deliciously simple in that the main input and output devices do not require many connections. This is usually a mixed blessing because less hardware, often means more software. The main devices used in the circuit are....
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The Schematic has three main parts to it. The Sensor Circuitry where the accelerometer is wired up to the A/D converters. The second part is the power circuit where we have the On/Off switch, the 3. 7v battery & +5v 7805 Voltage Regualtor. The 3rd part of....
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The Pyro Propeller Clock POV schematic is actually not very difficult. There are three main parts: the power supply which uses a 7805, the LED output control which uses the PIC18F252 and 74LS373 and the `home` trigger circuit which uses an IR emitter and....
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The schematic for this project flows naturally from left to right. Beginning at the antenna and the regenerative receiver front-end, then flowing through the amplification stages and then into the 555 timer. This is a very common regenerative receiver....
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After the wizardry that is our standard renegerative front-end receiver circuit, we will be able to see some initial output receiver from our transmitter. The point in the schematic we`ll look at first is right after the LC tuning circuit and DC blocking....
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The schematic for this project is actually deceivingly simple compared to the complexity of what is happening in the circuit. So take a look below or click to view the full sized schematic. The two signals we`ve just generated are mixed together at the base....
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Instead of focusing on the mathematical and raw theoretical side of this simple pyro RF transmitter, we`ll be focusing on the elements in each of the stages. The math of how/why this circuit actually works is horridly ugly and way too complicated. so it`s....
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The hardware schematic for the wooden menace (robotic arm) is fairly straight forward. The PIC microcontroller has one control line feeding to each servo and it also connects to the RJ45 connecter. The RJ45 connector is used for getting input from the....
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The schematic for this project is not terribly complex, however it is very important that you understand the circuit board and how it operates because of the high voltages that are generated. Below is a `rough draft` schematic of the camera used for this....
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The schematic for this project is fairly large and you can see the complete schematic below. To explain what is happening here I will split it into two sections which I will call the analog and digital sections. The schemtic below (click to enlarge it) is....
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The Tupperware Turret circuit is as simple as things can get whilst still maintaining full functionality. The main parts seen in the schematic below are the: 18F4520, Servo Motors, IR Receiver and TIP120. The batteries used for this project are 4 standard AA....
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There are actually very few electronic components necessary for this project as the PIC Microcontroller is the powerhouse doing most the work. The few components necessary like, buttons, switches & power circuit are trivial forms of I/O which makes....
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The schematic for this tutorial can be seen drawn out below. It includes everything you`d need to wire up for the tutorial to work. PIC programming circuitry is not included in the schematic as I`m assuming either you`re programming the PIC out of circuit or....
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The schematic is very simple for this tutorial. It is just a matter of wiring up the ADXL320 sensor to the PIC and the LED. The power circuitry assumes you have a battery of +5v to power the PIC. You can create your own custom circuitry for this or just use....
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The electronic designs for the two animatronic mouths can be seen below. The first design is for the articulated mouth, the extra servos are for the eyebrows and eyes. The second design is for the LCD mouth. It is very similar to the custom characters on an....
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The schematic for this project really only consists of adding a single 5mm LED to one digital output port on the Arduino. The picture below should be fairly self explanatory for how to do it. The main parts in the schematic are the Arduino Uno, 5mm LED and....
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The schematic for this project has been kept super simple with very few parts keeping the total cost very low and assembly time low. The main parts in the schematic are the PIC 18F452, Tilt Sensor and LED Bar. The power regulation circuit is in the lower....
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The schematic for controlling the motors is split up into three main parts, with each part having a unique functionality. The main parts used and seen in the schematic below are the 18F252, SN754410 and 2N2222 Transistors. Seen at the very top, the....
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The Proximity Sensor circuit can be seen below. Three red boxes show the additions to the circuit that we already built in Part 2: Motor Control. The new parts used and seen in the schematic below are the GP2Y0A21YK IR Sensor, Headphone Speaker and some....
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This schematic is taken directly from the Altera ByteBlaster datasheet or manual. They spill out all the fine print and details of how the connector works & what connections go where. Find the datasheet on their website or through google and give it a good....
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The schematic seen below uses all the hardware components we`ve seen up to this point. If you`re following along with this tutorial be sure to follow it exactly as seen below. If you don`t have 220k resistor use the closest value you can find near it,....
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The circuit for the Digital Tachometer/RPM Counter tutorial consists of only a few devices. Wire them up according to the following circuit diagram. The PIC I`m using is on a demonstration board, which means the clock, power and ground pins are already wired....
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The schematic for this project is a modified version of the CPLD dev board schematic. There are a few new parts added for this project and you can see the completed schematic for this project below. The main parts in the schematic are the CPLD Dev Board,....
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An issue with CPLD and FPGA devices is that they have so many I/O pins that their schematics become overwhemlingly HUGE very quickly. I tried my best to partition out different sections of the schematic to show the motor control circuit, a-to-d converter....
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The schematic for this project is a modified version of the CPLD dev board schematic. There are a few new parts added for this project and you can see the completed schematic for this project below. The main parts in the schematic are the CPLD Dev Board,....
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The 10A H-Bridge Motor Controller circuit looks simple but there are some key points that you don`t want to miss. The main devices used in the circuit are the TIP147, TIP142 and 2n2222. The power circuit is the +12v coming in from the terminal block....
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The I2C PIC Interfacing Tutorial circuit is not terribly difficult however it will take some double checking to make sure you have everything hooked up properly before working the first time. The main devices used in the circuit are the 18F452, 24LC02B and....
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The way that this receiver works is very similar to the way that we as humans beings work. We see colors and we act depending on the different things seen. The phototransistors does the same thing, if reacts depending upon the intensity of infrared light....
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The Infrared IR Receiver circuit is not particularly unique. The main components are the phototransistor, the microcontroler and the amplifier. If you can understand how these three devices transfer data, then you should have no problem getting the circuit....
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The music equalizer display schematic is not a very difficult one to build. I managed to fit it all on a nice little breadboard. You will need all the parts listed out on the previous page to put it together. It is quite wire-intensive so make sure you have....
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For the 2 layer board schematic, we`ll use 6 core IC`s: 4 74LS164`s and 2 555 Timers. The schematic will be built using Eagle Layout Editor since all the parts I need exist in their library. The final schematic can be seen below, click on the picture for the....
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The Quick and Easy Wireless circuit is not terribly difficult however it will take some double checking to make sure you have everything hooked up properly before working the first time. The main devices used in the circuit are the 7805, 18F452, RC Receiver....
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Although we`ll be using the Olimex P-40 development board, you can also breadboard out the circuit as it is very simple. The schematic for our first pass at controlling a servo is shown below. Servos can start to sink alot of current like any motors so it is....
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The simple motor optical encoder circuit is not terribly difficult however it will take some double checking to make sure you have everything hooked up properly before working the first time. The main devices used in the circuit are the 7805, 18F4520 and....
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Hardware design for USB is actually quite minimal, which is a big plus for us. However, what you quickly find out with USB is that the easy hardware design means the communication and control software is very complex, we`ll see more about that in the theory....
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The circuit for the rs232 serial interface is of mild complexity. The main parts of the circuit are the 18F4520, MAX233A and DB-9 Connector and these portions of the circuit will be described briefly below. This is a basic +5v power regulator circuit for the....
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The SN754410 Dual Motor Control circuit can be seen below. It is just about as simple as it looks with the PIC being the central processor. The main parts used and seen in the schematic below are the 7805, 18F452 and SN754410. The LM7805 +5v Regulator is....
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The schematic for the board can be seen below. The three main elements of the board are (1) the power input and voltage regulation, (2) the L297 input and outputs and (3) the L298 stepper motor control circuit. While the motor is powered by a raw +12v input,....
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This circuit is not fun to look at nor is it fun to implement, it takes a bit of effort. Since there are two coils in our stepper motor we`ll use two LMD18245`s to control the current flow through the coils. It is important to note that there are motor....
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The schematic is very similar to the one seen in the CPLD Development Board Tutorial because it`s basically the same board with a tiny addition. The new part of the schematic is in the lower right corner. 8 (DIP) Switches, a resistor array & some additional....
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The RF modules used in this schematic are very simple, with only a few extra pins required for power, ground and data. The main parts used in this schematic are the RF transmitter module, RF receiver module, 18F452 and 18F4520. You can see them below, as....
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The schematic for the transmitter in this project has 4 main parts, the Arduino UNO, the sharp IR distance sensor, the XBee Wireless Modules and the 16x2 LCD. You can see how these parts are connected together to build the system we want in the schematic....
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There are two schematics that we`ll look at to see how to build this transmitter/receiver system. The first one is the transmitter, with a variable trimpot input into RA0. The trimpot value will be sent out of the Tx pin of the PIC and to the Din pin of the....
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The great thing about these little Xbee modules is they take care of almost all the heavy lifting. As you can see below both the transmitter and the receiver circuits are drop-dead simple. The main devices used in the circuit are the Xbee Modules, PIC....
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First, the 4017`s aren`t initialized to a known state since the reset pins aren`t briefly forced high when the circuit powers on. The chips might usually power up in the normal reset condition, but that isn`t probably guaranteed by the IC manufacturer. This....
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This web page is a memorial to Mike Caughran, KL7R, who died suddenly in January 2007. Mike was a passionate experimenter who was embraced by the homebrew radio electronics community. He was best known as the co-creator of and sidekick to Bill Meara, M0HBR....
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Focus on measuring low-level, HF circuits with a return loss bridge ” topics such as using the bridge for antenna matching are omitted and readily found on the web. This web page contains minimal text and just relies on simple diagrams and photographs to....
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Building VFOs in 2011 might seem an irrelevant exercise given the move to and evolution of digital signal generators laden with bells and whistles like memories and audio or video frequency displays. A successful L-C VFO requires skill, patience and some....
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My first tasks involved buying some VHF parts + exploring the Butler crystal oscillator. Specifically, I`ll cover my experiences with the common base version of the Butler oscillator. Like HF, the VHF knowledge base contains ever-present lore. Consider the....
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Above ” 2 air variable capacitors and a copper clad board screwed onto a piece of wood for my bench musing. Regenerative receivers delight and amaze ” some builders take them very seriously. I respect this, but to me; they should be as simple as possible. I....
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This circuit describes a simple, 6-bit random number pseudo-generator used to study binary counters and in particular, shift registers. Some very basic background information about binary counters and shift registers is provided. In reality there are dozens....
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The LO system from the project entitled A Monoband SSB/CW Transceiver in Chapter 6 of EMRFD. The mega low (about -20 dBm) output from a diode ring mixing a VFO and crystal oscillator is triple tuned band-pass filtered and then amplified to +8 dBm. Continuing....
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Low-cost CW superhet receiver with a 4. 00 MHz Intermediate frequency. There is no AGC or RF gain control, however this receiver has good large signal handling capability. This receiver uses just 6 bipolar transistors and an op amp for reasonable volume into....
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By the addition of one integrated circuit and some passive components, I was able to convert my earlier developed 40-meter direct conversion receiver design into a superhet model. Anyone who has listened to 40 meters during the evening hours on the crowded....
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Everything, it seemed, functioned normally. To me was pleased both half-duplex and work from the pedal in the telegraphic regime, when operator has the capability transferring, to listen to in the pauses of his transfer and here to pass into the usual....
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Experiments in rust electrolysis. The idea of using electricity to convert rust back into iron is not a new one, and electrolysis has been used for metal restoration by collectors and archaeologists for decades and the results can be very impressive, with....
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This transmitter had its origins as a conventional shunt fed Hartley oscillator for 80 meters using a pair of 27 triodes connected in parallel; with 300 VDC on the plates of the 27`s, I was able to get about 4 watts output ( with decent stability ) for about....