Top Circuits Page 264
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This circuit interfaces a standard RC-control to a standard PC game port, see figure 1. The main target was to use the interface for the FMS flight simulator. The interface makes it possible to use a standard RC radio to control the FMS flight simulator....
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I picked up an LM386 Low Voltage Audio Amplifier. A little poking around and I found National Semiconductor`s data sheet, showing a schematicthat requires only 5 components for a gain of 20, and 7 for a gain of 200. Being the skeptical man I am, I built the....
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I managed to break my laptop, by reversing the polarity of a universal power supply. The repair shop diagnosed the problem as a failed motherboard, and asked for ‚¬659 to replace it. I found the price preposterous and the notion of throwing away a....
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The Fv-1 has internal circuitry to support an external crystal, preferably a 32768Hz watch crystal. These crystals are extremely inexpensive and widely available. Frequencies other than 32768Hz are available, but not as cheap and not as plentiful. If the....
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The motor is used to provide the mechanical output of the system, and to move the potentiomer to close the loop. For high power servos three-phase motors can be used. Potentiometer: For standard industrial applications a simple potentiometer can be used to....
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A potentiometer is controlling the firing point of the triac. Capacitor C4 is charged via resistors R3, R4, P1, and R5. After a certain time, dependant on the potentiometer, the charge contained in C4 is large enough for the dimmers diac D to start....
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This has been a fine week for the pet door. We actually have a fully functional prototype! The door itself is constructed of a high-tech polymer which is easy to work with and provided a quick means of prototyping the door mechanism. (Read: Legos) The door....
-
It makes sense to build your own individual joystick. Especially the flight simulation enthusiasts like to build cockpit parts with the look and feel of original aircraft parts. Such self made hardware needs an joystick controller that meets the requirements....
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Model aircraft pilots like to use PC-flight-simulator software to train the handling of model aircraft without the risk of the loss of real models. It makes sense to use the own model aircraft remote control (RC) as input devise for the software. This....
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Four 595s together to drive 7-segment displays and alsoadded code to acceptinput from the PC. Instead of using 10-LED bar graphs like I did last time, I`ve moved on to 7-segment displays - which are more challenging and provide a more meaningful output. The....
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A "servo slower" which has now evolved into a Servo Controller. `Servo slower` units are used to reduce the slew-rate (traverse time) of proportional servos. The most common use in model boats is to control the rotation of a servo-controlled gun turret,....
-
For this project the 1 1/4 meter Midland 13-509 ischosen, mainly because it`s use in several (transparent) links, which support the SRG 147. 20 repeater. First strip out several items not needed or otherwise to improve reliability and performance. That would....
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This document is written in attempt to include everyone interested in serious construction of a quality product. Its very technical, however, written openly and honestly. It`s designed for Amateur Radio (not commercial) at no cost to obtain and is open for....
-
This is the Sequencer circuit. Power to the Logic portion of the circuit is provided by a standard commercial "wall-wart" power adaptor supplying 6 VDC. The 555 timer IC provides the pulse train that drives the chase; the timing is adjustable with the 100K....
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Coolingmist Stage 3 HOM Trunkmount kit. I figure it`s about time to get this thing installed so I can enjoy HOM 24/7. My plan is to have one switch for arming the system, and a second push-button for the purge. However, since I have Stage 3 With Toys, I want....
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The way an engine management system monitors its Air / Fuel ratio is through the Oxygen Sensor (O2) stuck in the hot exhaust flow, usually before the catalytic converter. All O2 sensors are basically the same, with some being heated or others providing....
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Bus Pirate is a great tool for exploring new chips using your PC, without the need to integrate the chip into a MCU project. Once I received my unit, i decided to put it to the test by exploring an accelerometer with I2C/SPI interface the MMA7456L from....
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The RC transmitter uses a potentiometer for each axis, it acts as a voltage divider sending a voltage of 0. 5V (the middle position corresponds to 2. 5V) to the analog input that is converted into a pule of 1. 2ms that is sent over RF. This module converts....
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BattMan II is a computer controlled battery manager, intended for typical rechargeable batteries used by R/C and electronics hobbyists, as well as various consumer product batteries. BattMan II has the following capabilities: Works with Nickel-Cadmium....
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An expanded scale voltmeter (ESV) can save your plane. That may be a strong statement, but it`s true. The crucial radio link that lets you control your plane relies on nickel-cadmium (NiCd) batteries in the transmitter and receiver. If either of these....
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This project, which can charge a pair of AA Nickel Metal Hydride (NiMH) or Nickel Cadmium (NiCd) cells using a laptop`s USB port for power, arose to address part of that problem. (By the way, if you want to lighten your laptop load, take a look at the MoGo....
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This design is based on one published by Milan Lulic in the German magazine elektroModell. Mr. Lulic`s design is for surface mount technology (SMT) construction, whereas mine uses standard off-the-shelf components, and is therefore better suited to....
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I recently uncovered this schematic, that seems to be authentic and does not feature the 555 timer. Additionally if you check out the picture of Brian Davis on this page you can see him holding up the etch mask I don`t see anything that looks like a socket....
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Adapting one of my failed Tesla coils into a crystal radio set to show the neighborhood kids. I`ve run into the #1 problem everyone faces not enough antenna to generate a strong signal. I read somewhere that a proper AM antenna should be between 100 500 ft....
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A stereo valve phono pre built for me by a techie mate. He has the power transformer and all components needed besides the valves which he advised me to source myself based on what would be most suitable to my needs. So, all you experienced DIYers, if you....
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The project is a continuation of the 5kW Boost converter project. After a few failed attempts, I realized that I was really after more power, perhaps 10kW or so. I changed the title from 12kW to 8kW. While the converter is designed for 12kW, its very....
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This first DRSSTC of mine evolved from the ISSTC work I had been doing at the time. Talking with Jimmy Hynes, who built the first DRSSTC, I decided I would give it a try, though with some changes from his design. Jimmy`s DRSSTC used an oscillator to generate....
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a personal digital assistant introduced by in 1994. It was often called a palmtop computer, and it was notable that it was, with some minor exceptions, aMS-DOS-compatible computer in a palmtop format, complete with a monochrome graphic display, qwerty....
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This is just a quick post at the moment because the project isn`t done and I am distracted by other things. The thermostat for the central heater in my house became unreliable a week or two ago. My wife rang around and a new one from the manufacturer of the....
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Use some tiny blinking LED`s as fireflies. It takes a bit of electronics skill to do this project but it comes out really wonderful. LED`s are tiny Light Emitting Diodes. Thisis a picture of one of the LED`s I used for this project. It is rather small but it....
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This radio receiver built on a piece of wood uses only 5 transistors but will receive longwave beacons and VLF beacons, depending on the antenna unit connected. Uses our AMVC-384 capacitor and one of our "C" antennas. This page is still under construction as....
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An audio amplifier connected to the output will emit loud click sound for each lightning strike detected. When severe storms are approaching, this receiver will go crazy - producing hundreds of clicks per minute. This is a direct detection amplified....
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This device can`t be legally hooked up to the PSTN as there is all sorts of red tape you need to go through to get the device registered for that. The basic functional blocks of the English ringing converter are pretty simple. It has a ringing detector, a....
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In counter mode it provides 1Hz resolution up to 100Mhz. In timer mode maximum resolution is 0. 0000001 Hz up to 1Hz. Resolution is reduced by one digit for each additional decade. Multiple frequency updates per second by employing a sliding window for....
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This project displays how the Nokia 3310 LCD can be interfaced and driven using the PIC16F628 microcontroller. The code is written in Hi-Tech C and the character table is embeded in the source code. The Nokia LCD has 84x48 pixels and is divided to operate in....
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The Current Sensor Board contains an Atmel AVR AT90S8535 running at 8MHz which samples six ADC current inputs and uses the remaining two ADC inputs to control an integrating charge counter and packages the results up into data packets which are sent to the....
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The following video is of my test circuit of a 16 step analog sequencer based on Mauno Tuominen`s schematic for an analog CMOS sequencer based around at 4067n multiplexer/demultiplexer. You can see a DIY version of the sequencer here at studiomanus. com. I....
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There are only four components required, and the cost for these is around 70p, so it would be a good candidate for a classroom exercise. Even a cheap relay like the Omron G5LA-1 5DC can switch loads of 10A at 240V. A word of caution: don`t tinker with mains....
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This page describes my modifications to the RIG RX-2 receiver which enable it to be controlled remotely from a computer, using an RS-232 serial interface. The modifications are in two parts: some simple additional hardware, and a new firmware program for the....
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This is a set of plans for an inexpensive, high performance digital logic probe that you can build in a few hours. It is small enough to use a plastic ball-point pen as a chassis, giving it a personalized touch and added style. The main advantage of this....
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A speaker/microphone/transmit button circuit for the puxing 777 which probably works for all puxing radios. I decided to reverse-engineering an earphone/microphone headset that came with the radio to determine how it worked. I can`t claim that I`m an expert....
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The goal of such a machine (called an electrocardiograph, or ECG ) is to amplify, measure, and record the natural electrical potential created by the heart. Note that cardiac electrical signals are different than heart sounds, which are listened to with a....
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The core of any transmitter is usually an oscillator circuit, and in simple transmitters (i. e. , QRSS devices), it`s often a crystal. Frequency adjustment is accomplished by adjusting capacitance to ground on one of the crystal legs. Simple oscillators such....
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Create a rapid transmitter/receiver pair that anyone would have around their house. I decided that AM or FM radio would be good since everyone can receive that, and pondered how best to generate the necessary radio signal and modulate it appropriately. After....
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The 7th overtone of 18mhz (17m) is 144mhz (2m) smack dab in the CW region. Icarus a HAB project run on advertising revenue that seems successful and has launched many balloons with some awesome photos. Robert Harrison knows his stuff! Lessons in Electric....
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It`s similar to the Atari Punk synth, aka Forrest Mims` stepped tone generator, but uses two triangle wave oscillators that can be combined or used separately. A wave shaper and square wave LFO are used to increase the aural ridiculousness...
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The MP-P2 Power Supply is the supply designed to power the mother board and its complement of plug-on boards including the MP-09 Microprocessor Board, disk controller board, memory boards and up to eight interface boards on the SWTPC Computer system. It....
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Feed the cable through some hole in the chassis to the opposite side There, between fan and rear panel, you may install the IFD board upside down. Use a thin and flexible isolating material, as PE or PVC to prevent short circuits. The board should be placed....
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I liked the idea of distributed active RIAA correction and also the concept of using negative feedback to linearize the input stage. Now, the original Collin design has a few significant flaws (openly admitted by the author in the same article), one of them....
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This circuit is able to handle nine independent telephones (using a single telephone line pair) located at nine different locations, PDF Bidirectional telephone line simulator without using telephone lines, couple, test and demonstrate all types of telephone....
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Here we provided several schematic drawings of battery charger circuit. These circuits covered 5W~200W NiCd, NIMH, Lead-Acid, and Li-Ion/Polymer, LiFePo4 battery packs. We hope chargers circuits files can help our users to select correct chargers also can....
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If there are more than some 5mV, reduce this offset value by experimenting with resistors (220K a good starting point) from testpoint Z (junction of R22/R23) to +v if there is a negative voltage or to -v if there is a positive voltage until the voltage at....
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A while ago I was doing some fairly trivial repairs on a Philips portable radio/CD/cassette player. It had a sticker on it claiming that this particular product features something called Dynamic Bass Boost. From the outside this means an extra switch, that....
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This circuit is easy to recognise by the three equal-value capacitors and two equal-value resistors connected to the base of the transistor. We have already mentioned the signal at the output of a transistor connected in COMMON EMITTER mode is FALLING when....
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The search loop may be constructed in several different ways; however, the method offered here should get you headed in the right direction. Refer to Fig. 2 as a guide for constructing the loop. The loop form should be constructed from non-metallic and....
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This project comes via two circuits on 2 boards. The first circuit is designed around a PIC16F628A. It has been presented on an experimental PC board using surface-mount components and was built in less than 1 hour, with about 2 hours to write and finalise....
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This circuit will detect AC line currents of about 250mA or more without making any electrical connections to the line. Current is detected by passing on of the AC lines through an inductive pickup (L1) made with a 1 inch diameter U-bolt wound with 800 turns....
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A number of simple FM devices, (without the use of a crystal) and showed how the power and frequency depends on a number of factors including the voltage of the supply and the design of the stages. The broad term given to the oscillator stage of these....
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For a project such as a robot or car, we need an ELECTRONIC circuit - one that is controlled by a "CONTROL CIRCUIT". The Control Circuit outputs a signal (or a number of signals) to control an H-Bridge. Here is a circuit of a Hex Bug. The Control Circuit....
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At this point you whistle into the receiver and the Infinity Bug will pick up the line. The high-gain amplifier in the Infinity Bug will pick up the audio at the place where it is located. It can only be assembled on the PC board supplied in the kit as the....
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This project is an extension of Metal Detector MkI, and shows how metal objects are detected. It is the second in a series of circuits and allows a great deal of experimentation, especially if you have a CRO (Cathode Ray Oscilloscope) and a few items to....
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A grasshopper is a switch that is ready to go off at any time. A piece of plastic is placed between two switch contacts to keep them apart and connected to cotton thread fixed to the floor. When the object is moved, the cotton pulls the plastic out of the....
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It`s most useful application is as a Signal Injector for radios and TV`s. A square wave is the most suitable for testing the IF (Intermediate Frequency) strip as the signal will pass through the IF transformers without any attenuation, no matter what the....
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Time would be much better spent on explaining transistor and MOSFET behaviour in a simpler way and getting on with digital circuitry and microcontroller projects. You simply cannot put a transistor into a circuit and expect it to produce the calculated....
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The three circuits above provide a constant current through the LED (or LEDs) when the supply rises to 15v and higher. The second and third circuits can be turned on and off via the input line. This is done by turning on the top transistor via the....
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This is one of the smallest and neatest FM transmitters to be presented as a construction project and it has the advantage of being available as a complete kit of parts. This will save going to a number of suppliers as no single supplier has all the....
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The doorbell operates on the 303MHz band and the 30 metre range (100ft) is obtained without the use of an antenna! The circuit is actually radiating from the printed track of the tank circuit. The Tank Circuit is a single-turn coil and a small capacitor (5p....
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This project generates 350V DC and stores the voltage in a large electrolytic. This voltage will not kill you, but will deliver a nasty SHOCK! For this reason, the project has a great benefit. It will teach you to work very carefully on equipment with high....
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V1 and V2 are 12AX7 dual triodes. Each half of V1 is wired as a Class A voltage amplifier in a configuration known as Common Cathode. By comparison, both halves of V2 are wired together in the Cathode Follower configuration for current gain. Don ’t freak....
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This project is intended to support a simple course in which a student builds a simple AVR/Arduino based badge - a beginner`s soldering project producing a simple object with blinky lights that can be hung around the neck from a lanyard or pinned to a jacket....
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Flight Computer V1. 0: B1 PC Board U1 80C32 microprocessor U2 27C256-12 32Kx8 ROM - 120nS U3 74HC373 U4 LM340T-5 5v regulator (might be a 7805 part) U5 43C256-15 32Kx8 RAM - 150nS U6 74HC00 T1-T4 2N6045 or 2N6044 darlington output transistors Y1 11MHz....
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Flight Computer V1. 0: B1 PC Board U1 80C32 microprocessor U2 27C256-12 32Kx8 ROM - 120nS "V2. 1" U3 74HC373 U4 LM340T-5 5v regulator (might be a 7805 part) U5 43256-15 32Kx8 RAM - 150nS U6 74HC00 T1-T4 2N6045 or 2N6044 darlington output transistors Y1 11MHz....
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Until quite recently spread spectrum techniques were almost exclusively in the military domain. Their use in GPS and the latest cellular phones will be followed by many other civil applications. This article, the first of [two] parts, examines the technology....
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This part of the I2C interfacing project focuses on building an acceleration sensor, but in the process it also explores two other issues: advanced use of the PCF8591 chip (that we have already seen in the pressure sensor) and running the bus at 3. 3v. For....
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If you switch gears over 5k during a solar eclipse you`ll have to have your nut bearings revalved. There is a lot that goes into it. Same goes for making a sammich. They`re Fedders Inverter units. 12K & 18K. I understand they`re tricky to get the charge....
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This circuit converts the ripple from a wall wart supply to a clean Line x 2 digitial clock. Doing it this way eliminates the need to put AC into the unit which then has to be rectified and filtered just to have access to the line frequency sine wave...
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I have a 69 Princeton Reverb which is labled as having an AA764 circuit. When perusing various web resources for Fender Amplifier Schematics....
This circuit interfaces a standard RC-control to a standard PC game port, see figure 1. The main target was to use the interface for the FMS flight simulator. The interface makes it possible to use a standard RC radio to control the FMS flight simulator....
I picked up an LM386 Low Voltage Audio Amplifier. A little poking around and I found National Semiconductor`s data sheet, showing a schematicthat requires only 5 components for a gain of 20, and 7 for a gain of 200. Being the skeptical man I am, I built the....
I managed to break my laptop, by reversing the polarity of a universal power supply. The repair shop diagnosed the problem as a failed motherboard, and asked for ‚¬659 to replace it. I found the price preposterous and the notion of throwing away a....
The Fv-1 has internal circuitry to support an external crystal, preferably a 32768Hz watch crystal. These crystals are extremely inexpensive and widely available. Frequencies other than 32768Hz are available, but not as cheap and not as plentiful. If the....
The motor is used to provide the mechanical output of the system, and to move the potentiomer to close the loop. For high power servos three-phase motors can be used. Potentiometer: For standard industrial applications a simple potentiometer can be used to....
A potentiometer is controlling the firing point of the triac. Capacitor C4 is charged via resistors R3, R4, P1, and R5. After a certain time, dependant on the potentiometer, the charge contained in C4 is large enough for the dimmers diac D to start....
This has been a fine week for the pet door. We actually have a fully functional prototype! The door itself is constructed of a high-tech polymer which is easy to work with and provided a quick means of prototyping the door mechanism. (Read: Legos) The door....
It makes sense to build your own individual joystick. Especially the flight simulation enthusiasts like to build cockpit parts with the look and feel of original aircraft parts. Such self made hardware needs an joystick controller that meets the requirements....
Model aircraft pilots like to use PC-flight-simulator software to train the handling of model aircraft without the risk of the loss of real models. It makes sense to use the own model aircraft remote control (RC) as input devise for the software. This....
Four 595s together to drive 7-segment displays and alsoadded code to acceptinput from the PC. Instead of using 10-LED bar graphs like I did last time, I`ve moved on to 7-segment displays - which are more challenging and provide a more meaningful output. The....
A "servo slower" which has now evolved into a Servo Controller. `Servo slower` units are used to reduce the slew-rate (traverse time) of proportional servos. The most common use in model boats is to control the rotation of a servo-controlled gun turret,....
For this project the 1 1/4 meter Midland 13-509 ischosen, mainly because it`s use in several (transparent) links, which support the SRG 147. 20 repeater. First strip out several items not needed or otherwise to improve reliability and performance. That would....
This document is written in attempt to include everyone interested in serious construction of a quality product. Its very technical, however, written openly and honestly. It`s designed for Amateur Radio (not commercial) at no cost to obtain and is open for....
This is the Sequencer circuit. Power to the Logic portion of the circuit is provided by a standard commercial "wall-wart" power adaptor supplying 6 VDC. The 555 timer IC provides the pulse train that drives the chase; the timing is adjustable with the 100K....
Coolingmist Stage 3 HOM Trunkmount kit. I figure it`s about time to get this thing installed so I can enjoy HOM 24/7. My plan is to have one switch for arming the system, and a second push-button for the purge. However, since I have Stage 3 With Toys, I want....
The way an engine management system monitors its Air / Fuel ratio is through the Oxygen Sensor (O2) stuck in the hot exhaust flow, usually before the catalytic converter. All O2 sensors are basically the same, with some being heated or others providing....
Bus Pirate is a great tool for exploring new chips using your PC, without the need to integrate the chip into a MCU project. Once I received my unit, i decided to put it to the test by exploring an accelerometer with I2C/SPI interface the MMA7456L from....
The RC transmitter uses a potentiometer for each axis, it acts as a voltage divider sending a voltage of 0. 5V (the middle position corresponds to 2. 5V) to the analog input that is converted into a pule of 1. 2ms that is sent over RF. This module converts....
BattMan II is a computer controlled battery manager, intended for typical rechargeable batteries used by R/C and electronics hobbyists, as well as various consumer product batteries. BattMan II has the following capabilities: Works with Nickel-Cadmium....
An expanded scale voltmeter (ESV) can save your plane. That may be a strong statement, but it`s true. The crucial radio link that lets you control your plane relies on nickel-cadmium (NiCd) batteries in the transmitter and receiver. If either of these....
This design is based on one published by Milan Lulic in the German magazine elektroModell. Mr. Lulic`s design is for surface mount technology (SMT) construction, whereas mine uses standard off-the-shelf components, and is therefore better suited to....
I recently uncovered this schematic, that seems to be authentic and does not feature the 555 timer. Additionally if you check out the picture of Brian Davis on this page you can see him holding up the etch mask I don`t see anything that looks like a socket....
Adapting one of my failed Tesla coils into a crystal radio set to show the neighborhood kids. I`ve run into the #1 problem everyone faces not enough antenna to generate a strong signal. I read somewhere that a proper AM antenna should be between 100 500 ft....
A stereo valve phono pre built for me by a techie mate. He has the power transformer and all components needed besides the valves which he advised me to source myself based on what would be most suitable to my needs. So, all you experienced DIYers, if you....
The project is a continuation of the 5kW Boost converter project. After a few failed attempts, I realized that I was really after more power, perhaps 10kW or so. I changed the title from 12kW to 8kW. While the converter is designed for 12kW, its very....
This first DRSSTC of mine evolved from the ISSTC work I had been doing at the time. Talking with Jimmy Hynes, who built the first DRSSTC, I decided I would give it a try, though with some changes from his design. Jimmy`s DRSSTC used an oscillator to generate....
a personal digital assistant introduced by in 1994. It was often called a palmtop computer, and it was notable that it was, with some minor exceptions, aMS-DOS-compatible computer in a palmtop format, complete with a monochrome graphic display, qwerty....
This is just a quick post at the moment because the project isn`t done and I am distracted by other things. The thermostat for the central heater in my house became unreliable a week or two ago. My wife rang around and a new one from the manufacturer of the....
Use some tiny blinking LED`s as fireflies. It takes a bit of electronics skill to do this project but it comes out really wonderful. LED`s are tiny Light Emitting Diodes. Thisis a picture of one of the LED`s I used for this project. It is rather small but it....
This radio receiver built on a piece of wood uses only 5 transistors but will receive longwave beacons and VLF beacons, depending on the antenna unit connected. Uses our AMVC-384 capacitor and one of our "C" antennas. This page is still under construction as....
An audio amplifier connected to the output will emit loud click sound for each lightning strike detected. When severe storms are approaching, this receiver will go crazy - producing hundreds of clicks per minute. This is a direct detection amplified....
This device can`t be legally hooked up to the PSTN as there is all sorts of red tape you need to go through to get the device registered for that. The basic functional blocks of the English ringing converter are pretty simple. It has a ringing detector, a....
In counter mode it provides 1Hz resolution up to 100Mhz. In timer mode maximum resolution is 0. 0000001 Hz up to 1Hz. Resolution is reduced by one digit for each additional decade. Multiple frequency updates per second by employing a sliding window for....
This project displays how the Nokia 3310 LCD can be interfaced and driven using the PIC16F628 microcontroller. The code is written in Hi-Tech C and the character table is embeded in the source code. The Nokia LCD has 84x48 pixels and is divided to operate in....
The Current Sensor Board contains an Atmel AVR AT90S8535 running at 8MHz which samples six ADC current inputs and uses the remaining two ADC inputs to control an integrating charge counter and packages the results up into data packets which are sent to the....
The following video is of my test circuit of a 16 step analog sequencer based on Mauno Tuominen`s schematic for an analog CMOS sequencer based around at 4067n multiplexer/demultiplexer. You can see a DIY version of the sequencer here at studiomanus. com. I....
There are only four components required, and the cost for these is around 70p, so it would be a good candidate for a classroom exercise. Even a cheap relay like the Omron G5LA-1 5DC can switch loads of 10A at 240V. A word of caution: don`t tinker with mains....
This page describes my modifications to the RIG RX-2 receiver which enable it to be controlled remotely from a computer, using an RS-232 serial interface. The modifications are in two parts: some simple additional hardware, and a new firmware program for the....
This is a set of plans for an inexpensive, high performance digital logic probe that you can build in a few hours. It is small enough to use a plastic ball-point pen as a chassis, giving it a personalized touch and added style. The main advantage of this....
A speaker/microphone/transmit button circuit for the puxing 777 which probably works for all puxing radios. I decided to reverse-engineering an earphone/microphone headset that came with the radio to determine how it worked. I can`t claim that I`m an expert....
The goal of such a machine (called an electrocardiograph, or ECG ) is to amplify, measure, and record the natural electrical potential created by the heart. Note that cardiac electrical signals are different than heart sounds, which are listened to with a....
The core of any transmitter is usually an oscillator circuit, and in simple transmitters (i. e. , QRSS devices), it`s often a crystal. Frequency adjustment is accomplished by adjusting capacitance to ground on one of the crystal legs. Simple oscillators such....
Create a rapid transmitter/receiver pair that anyone would have around their house. I decided that AM or FM radio would be good since everyone can receive that, and pondered how best to generate the necessary radio signal and modulate it appropriately. After....
The 7th overtone of 18mhz (17m) is 144mhz (2m) smack dab in the CW region. Icarus a HAB project run on advertising revenue that seems successful and has launched many balloons with some awesome photos. Robert Harrison knows his stuff! Lessons in Electric....
It`s similar to the Atari Punk synth, aka Forrest Mims` stepped tone generator, but uses two triangle wave oscillators that can be combined or used separately. A wave shaper and square wave LFO are used to increase the aural ridiculousness...
The MP-P2 Power Supply is the supply designed to power the mother board and its complement of plug-on boards including the MP-09 Microprocessor Board, disk controller board, memory boards and up to eight interface boards on the SWTPC Computer system. It....
Feed the cable through some hole in the chassis to the opposite side There, between fan and rear panel, you may install the IFD board upside down. Use a thin and flexible isolating material, as PE or PVC to prevent short circuits. The board should be placed....
I liked the idea of distributed active RIAA correction and also the concept of using negative feedback to linearize the input stage. Now, the original Collin design has a few significant flaws (openly admitted by the author in the same article), one of them....
This circuit is able to handle nine independent telephones (using a single telephone line pair) located at nine different locations, PDF Bidirectional telephone line simulator without using telephone lines, couple, test and demonstrate all types of telephone....
Here we provided several schematic drawings of battery charger circuit. These circuits covered 5W~200W NiCd, NIMH, Lead-Acid, and Li-Ion/Polymer, LiFePo4 battery packs. We hope chargers circuits files can help our users to select correct chargers also can....
If there are more than some 5mV, reduce this offset value by experimenting with resistors (220K a good starting point) from testpoint Z (junction of R22/R23) to +v if there is a negative voltage or to -v if there is a positive voltage until the voltage at....
A while ago I was doing some fairly trivial repairs on a Philips portable radio/CD/cassette player. It had a sticker on it claiming that this particular product features something called Dynamic Bass Boost. From the outside this means an extra switch, that....
This circuit is easy to recognise by the three equal-value capacitors and two equal-value resistors connected to the base of the transistor. We have already mentioned the signal at the output of a transistor connected in COMMON EMITTER mode is FALLING when....
The search loop may be constructed in several different ways; however, the method offered here should get you headed in the right direction. Refer to Fig. 2 as a guide for constructing the loop. The loop form should be constructed from non-metallic and....
This project comes via two circuits on 2 boards. The first circuit is designed around a PIC16F628A. It has been presented on an experimental PC board using surface-mount components and was built in less than 1 hour, with about 2 hours to write and finalise....
This circuit will detect AC line currents of about 250mA or more without making any electrical connections to the line. Current is detected by passing on of the AC lines through an inductive pickup (L1) made with a 1 inch diameter U-bolt wound with 800 turns....
A number of simple FM devices, (without the use of a crystal) and showed how the power and frequency depends on a number of factors including the voltage of the supply and the design of the stages. The broad term given to the oscillator stage of these....
For a project such as a robot or car, we need an ELECTRONIC circuit - one that is controlled by a "CONTROL CIRCUIT". The Control Circuit outputs a signal (or a number of signals) to control an H-Bridge. Here is a circuit of a Hex Bug. The Control Circuit....
At this point you whistle into the receiver and the Infinity Bug will pick up the line. The high-gain amplifier in the Infinity Bug will pick up the audio at the place where it is located. It can only be assembled on the PC board supplied in the kit as the....
This project is an extension of Metal Detector MkI, and shows how metal objects are detected. It is the second in a series of circuits and allows a great deal of experimentation, especially if you have a CRO (Cathode Ray Oscilloscope) and a few items to....
A grasshopper is a switch that is ready to go off at any time. A piece of plastic is placed between two switch contacts to keep them apart and connected to cotton thread fixed to the floor. When the object is moved, the cotton pulls the plastic out of the....
It`s most useful application is as a Signal Injector for radios and TV`s. A square wave is the most suitable for testing the IF (Intermediate Frequency) strip as the signal will pass through the IF transformers without any attenuation, no matter what the....
Time would be much better spent on explaining transistor and MOSFET behaviour in a simpler way and getting on with digital circuitry and microcontroller projects. You simply cannot put a transistor into a circuit and expect it to produce the calculated....
The three circuits above provide a constant current through the LED (or LEDs) when the supply rises to 15v and higher. The second and third circuits can be turned on and off via the input line. This is done by turning on the top transistor via the....
This is one of the smallest and neatest FM transmitters to be presented as a construction project and it has the advantage of being available as a complete kit of parts. This will save going to a number of suppliers as no single supplier has all the....
The doorbell operates on the 303MHz band and the 30 metre range (100ft) is obtained without the use of an antenna! The circuit is actually radiating from the printed track of the tank circuit. The Tank Circuit is a single-turn coil and a small capacitor (5p....
This project generates 350V DC and stores the voltage in a large electrolytic. This voltage will not kill you, but will deliver a nasty SHOCK! For this reason, the project has a great benefit. It will teach you to work very carefully on equipment with high....
V1 and V2 are 12AX7 dual triodes. Each half of V1 is wired as a Class A voltage amplifier in a configuration known as Common Cathode. By comparison, both halves of V2 are wired together in the Cathode Follower configuration for current gain. Don ’t freak....
This project is intended to support a simple course in which a student builds a simple AVR/Arduino based badge - a beginner`s soldering project producing a simple object with blinky lights that can be hung around the neck from a lanyard or pinned to a jacket....
Flight Computer V1. 0: B1 PC Board U1 80C32 microprocessor U2 27C256-12 32Kx8 ROM - 120nS U3 74HC373 U4 LM340T-5 5v regulator (might be a 7805 part) U5 43C256-15 32Kx8 RAM - 150nS U6 74HC00 T1-T4 2N6045 or 2N6044 darlington output transistors Y1 11MHz....
Flight Computer V1. 0: B1 PC Board U1 80C32 microprocessor U2 27C256-12 32Kx8 ROM - 120nS "V2. 1" U3 74HC373 U4 LM340T-5 5v regulator (might be a 7805 part) U5 43256-15 32Kx8 RAM - 150nS U6 74HC00 T1-T4 2N6045 or 2N6044 darlington output transistors Y1 11MHz....
Until quite recently spread spectrum techniques were almost exclusively in the military domain. Their use in GPS and the latest cellular phones will be followed by many other civil applications. This article, the first of [two] parts, examines the technology....
This part of the I2C interfacing project focuses on building an acceleration sensor, but in the process it also explores two other issues: advanced use of the PCF8591 chip (that we have already seen in the pressure sensor) and running the bus at 3. 3v. For....
If you switch gears over 5k during a solar eclipse you`ll have to have your nut bearings revalved. There is a lot that goes into it. Same goes for making a sammich. They`re Fedders Inverter units. 12K & 18K. I understand they`re tricky to get the charge....
This circuit converts the ripple from a wall wart supply to a clean Line x 2 digitial clock. Doing it this way eliminates the need to put AC into the unit which then has to be rectified and filtered just to have access to the line frequency sine wave...
I have a 69 Princeton Reverb which is labled as having an AA764 circuit. When perusing various web resources for Fender Amplifier Schematics....
