Top Circuits Page 230
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This is a Sony Triniton, Model KV-20M10, manufactured July 1995. There are no blinking lights (there really are no lights to blink) or clicking sounds. The described symptom on this particular model using a BA-2 chassis would indicate an internal hardware....
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A Code Practice Oscillator and that I must have built it some time ago. I had a vague recollection of the project. It certainly looked like something I might have built. There was a straight key in the same box that plugged right into the key jack. I opened....
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The most important part of a school`s CATV-CCTV system, is the process of planning for its infrastructure and the actual plan itself. The schools planning ideally is best facilitated when it involves all the school`s role groups as well as the district and....
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Electronic equipment is not `cheap` and can be damaged in a number of ways, by electro-static discharge, by lightning and by transmitting withno antenna attached, or into an antenna with a high SWR. The controller described herein attempts to facilitate the....
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While working two-meter SSB from the Benson area, I decided that local terrain and the limited height of my home-made six-element yagi, necessitate I incorporate a high gain antenna pre-amplifier at it`s terminations to enhance receiver signal strength. This....
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This 18 dB gain amplifier was built Manhattan-style to evaluate the Linear Technology LT1253 dual video amplifier as a candidate output amplifier for DDS systems employing the Analog Devices AD9850 and similar devices. This dual amplifier was chosen to take....
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This is the remainder of the receiver, including the post mixer amplifier, variable crystal filter, i. f. amplifier, product detector, local oscillator, receiver muting, and audio amplifier. The transmit section, showing the local oscillator, Tx single....
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Here is the design of an audio oscillator that runs at approximately 1 KHz. I don`t remember where I got this circuit, probably from EMFRD, since Wes`s book is a treasure trove of useful circuits. This handy oscillator can be used as a source of audio for....
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The Precision VXO (PVXO) and its matching Crystal Test Fixture (CTF) were created to provide a low cost means of evaluating the characteristics of crystals and a means of measuring their series resonant frequency. With this information, one can then build....
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Designing and building an AM Broadcast Sucker-outer. The undesired AM broadcast signal is shunted to ground with a series resonant circuit consisting of L1 and C1, C2, and C3. At the HF frequencies, this series circuit will look like an inductor from Input....
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Construction of a radio telephone integrator and created my first radio phone / repeater. I had been playing with electronics and radios since that first receiver I had built back in 1973. With that simple receiver and a random wire antenna I had discovered....
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The Kenwood TM-733A is an older dual-band mobile radio. This radio is capable of 50 watts transmit on VHF, 35 watts on UHF, full-duplex crossband repeat, and simultaneous receive on two VHF or UHF frequencies. It does have a problem, however: It is terribly....
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High-energy capacitors of the type discussed can produce hundreds of amps when short-circuited, possibly causing severe burns, fire and/or property damage! Please be aware of these hazards when using these capacitors and take precautions to avoid....
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The 2SK2975 was reportedly been discontinued by the manufacturer and the replacement part was the RD07MVS1 manufactured by Mitsubishi. This device is very similar - but it seems to have slightly higher gain than the `2975 (10 db typ. at 520 MHz versus 8. 4....
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A plot showing the paths of the recently-tracked and currently-tracked satellites. The receiver`s location is the "bull`s eye" in the center while the top of the plot represents the North pole. The red line shows the "EFC" value - the setting of the....
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A PIC16x84 processor may be used to generate a PSK31 or FSK31 signal. This could be used for beacon transmissions (as described here) or they may be used for telemetry, experimental, or even QSOs - the latter being true if you are willing to put up with a....
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This is a "quick-and-dirty" page that I set up to describe the T1-rate modem that I designed several years ago (in 1993, actually. ) Let me point out that unless you are going to use this on wires, this modem is absolutely useless to anyone other than....
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Inside the outdoor box to which the loop is mounted showing the amplifier circuitry. The four capacitors visible at the lower-left corner of the perfboard are used to broadly resonate the receive loop. In the office building in which he worked (a city....
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One is in a leather bag and is model EE-8-A. One or more is in a canvas bag and is EE-8-B. All have handsets with the butterfly push-to-talk lever. The -B model does have an original handset and cord. These have been tested in both LB and CB modes and work....
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The EE-91 is a wall mounted metal telephone box. It is a common battery phone which means transmitter current is obtained from the central office battery. It is equipped with a single gong ringer. It has a hand generator for signalling magneto lines. It has....
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The video-mixer no longer requires a supply voltage. This supply voltage could introduce moire problems if too noisy. As seen in my schematic above the video-mixer does not have an open-emitter buffer stage for any of the signals. (the original reference....
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It is important to layout your PCB correctly to allow trouble free In System Programming of AVR microcontrollers. This guide covers the usual problems that are encountered and typical AVR ISP circuit schematics. This guide covers Serial Programming, which is....
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Microchip do not recommend any particular circuit for ICSP programming. There are diagrams for different tools, such as Pro Mate and PICKit2 with similar circuitry but slight variations. In some schematics, their suggested resistor values are too small, in....
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Direct-reading" SWR meters that automatically compute the ratio of Forward and Reverse powers (i. e. you don`t have to adjust any sensitivity controls). Several years ago I built one to a design by G3WPO that was sold as a kit by Cirkit. It worked quite....
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Development board for 18 pin PIC microcontrollers with power supply circuit, crystal oscillator circuit, RS232 port, ICSP/ICD port, 4 relay output, 4 optocoupler isolated inputs...
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If you need lots of Analog to Digital channels, or plenty of program space (up to 32K!), this one is for you! Prototype board for 40 pin PIC microcontrollers with power supply circuit, 20MHz crystal oscillator circuit, RS232 port, ICSP/ICD programming port...
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I removed the entire setup from a bike awhile back and it ran then, and also ran about a year ago in the engine stand that it`s currently mounted in now. This afternoon I went to start the thing up to test things out before selling it off and hit a glitch.....
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Here`s a Regenerative Receiver project that I designed for the 80 meter Amateur band, but which can also be used in a wider-tuning configuration that covers approximately 3 MHz to 10 MHz, for Shortwave (World Band) listeners. Built in the same style as my....
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Here`s a dual-band Regen that came from some encouraging emails from Jerry (K9UT) and another gentleman named Harvey, who built my original AGC-80, and its experimental "Regenerodyne" successor, the AGC-80/30. Jerry and I have corresponded on several....
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Here`s something that might intrigue you Crystal Radio builders out there: A one-transistor (Silicon, yet!) AM broadcast receiver that derives its power from ambient AC hum and `spherics [static crashes]! Gotta give credit when I can: The germ of the....
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A standard 12-volt auto electrical system can be considered to be a powerful but unreliable source of low-voltage DC current. Some of the features any mobile PC installation should provide include: Automotive systems must be designed to strict electrical....
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The CODE and CONST memory classes are typically stored in ROM that may be either off-chip or on-chip. The CODE memory class is used for the actual program code while the CONST memory class is used for constant variables declared in code space. In addition,....
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This interface schematic shows the JTAG, Serial Wire, and ETM interface circuits of ULINKpro. Use this schematic to analyze potential problems with the target hardware. ARM websites use two types of cookie: (1) those that enable the site to function and....
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The basic circuit described in this document is capable of generating up to 30 kilovolts or more from a low voltage DC source using the flyback (LOPT) transformer salvaged from a B/W or color TV or computer monitor. Typical output with a 12 VDC 2 A power....
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The circuit is split into two sections: the isolated external loop which is connected to the remote interface connector on the front of the PSU and the non-isolated inner loop which is connected to the HT (AC line) supply. The two loops are linked by....
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The nitrogen (N2) laser produces intense extremely short (a few ns) intense (100 kW typical) pulses of light in the near UV portion of the E/M spectrum (337. 1 nm). Despite this impressive capability, the N2 laser is among the easiest to construct for the....
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This chapter contains circuit diagrams for several power supplies for pulsed solid state lasers. These include units suitable for driving the popular Hughes ruby and YAG rangefinder laser assemblies as well, one using the flash from a disposable pocket....
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A very precise digital thermometer with LM35 probe (0, 1 degree of freedom). The circuit has two adjustments. One of them, R5, adjusts the displays to 0. To perform this, we have to connect the extreme part of R4 (that goes to the temperature probe) to the....
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This simple circuit is based on the well-known integrated circuit LM3915. The main characteristic of this integrated circuit is its power to manage 10 LED-s (Light Emitting Diodes) in logarithmic scale with a difference between the 3dB LED-s, which it can....
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Each power supply, whether linear or switcher, uses at least two operating modes that characterize its operation: constant voltage (CV) and constant current (CC). The power supply can work in either one, while the other is usually a protective mode, both for....
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Using PC`s parallel port is a convenient way to control a stepper motor. For unipolar stepper motors, up to two motors can be controlled with the 8bit data line. The standard way of connecting a unipolar stepper motor to the parallel port is to use a....
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H-bridge is frequently used to control DC motors and stepper motors. When controlling a bipolar stepper motor, two full H-bridges are needed. There are many H-bridge ICs (like L298, MPC17529 and SN754410 which is a quad half H-bridge) for just that purpose.....
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Building an LC meter for a while since I do not have a multimeter that is capable of measuring inductance and while the multimeters I have can measure capacitance, they are not able to give accurate readings for small capacitance in the range of several....
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While most commercial grade signal generators offer more than just outputting a sinusoidal waveform, they are quite pricey for casual use. In this article, I will show you a simple wide band signal generator that is built around a Linear Technology`s LTC6905....
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Some ultrasonic range finders for my project. But most of the commercial sensors like Parallax`s PING sensor and other similar products are quite expensive, especially if multiple units are needed. So I thought why not building it myself The theory behind....
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This thermometer uses an LM19 sensor calibrated for measuring a wide temperature range (-55 130 Celsius, -67 266 Fahrenheit) for outdoor temperature measurement and an SHT21 digital thermometer with humidity measurement for indoor use. An ATmega328....
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The drive circuits for Unipolar stepper motors are usually very simple. In its simplest form, a transistor or MOSFET is used to drive each section of the windings. With this design, the control signal must be supplied programmatically to the four windings of....
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Typically a synchronous camera flash (e. g. slave flash) is triggered via an SCR. In this blog post, I will show you a circuit that can be used to trigger a secondary camera flash using an IGBT. Using an IGBT for camera flash triggering has several....
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A wireless temperature sensor so that temperature measurements can be made anywhere within the range of the transmitter and the receiver. There are many ways to achieve this. One of the simplest ways is to use a voltage to frequency conversion chip along....
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A used 250VA power transformer that was removed from equipment a couple of weeks ago. The transformer has a dual 10V AC output and a few auxiliary voltage outputs. The 10V winding is rated at 10A, I thought it would be perfect for a high current power supply....
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A simple Zenner diode tester circuit, when coupled with a PWM generator it can be used to measure the breakdown voltage of Zener diodes. Or more generically, it can be used to measure the breakdown voltages (e. g. BVceo, BVcbo) of BTJ transistors. As you can....
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A project on temperature/humidity logging a couple of years ago. In that project I logged the temperature and humidity readings in my basement lab over the course of a year. One issue with the approach I took back then was that the data could not be observed....
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The current sourcing/sinking capability of the I/O pins on Raspberry Pi is quite limited. According to the Wiki page, the current limit for each I/O block (e. g. GPIO0 through GPIO27 combined) comes at only 26 mA maximum, which is only capable of driving a....
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A teardown of a BK Precision 4011 5MHz function generator a few weeks ago. Like most of basic function generators in old days, BK 4011 does not offer frequency sweep as an option. What it does include is a VCG (Voltage controlled Generator) input, which....
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A tracking mount for trusty Minolta SRT-101. My untracked photos of Hyakutake had not done the comet justice; the exposures were too short. If one mounts a camera to a sturdy tripod and opens the shutter for several minutes, the developed picture will be....
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To increase one`s chances of seeing the northern lights, the uncertainties of existing aurora prediction methods can be bypassed by sensing the light from the aurora directly. The Aurora Alarm is a device which accomplishes this objective through the use of....
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A MIDI interface for an automatic accompaniment or controlling an MIDI expander. MIDIvice supports both manuals and has some nifty program features. It`s a MIDI output interface for upper and lower manual, working with a dirt-cheap 8031 and single-sided PCBs....
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I`ve been doing some CW contesting with my K2 and N3FJP`s Logging Software and since I now have this modern rig with computer control and everything I wanted to connect it up to my old Thinkpad and use the serial port for rig control and the parallel port....
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The ADEV Development System consists of the ATAR Target Module and the ADEV Test/Programming Module. The ATAR Target Module and the ADEV Test/Programming Module, together with development tools from Silicon Laboraties, Inc. (SL), can be used to develop....
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The following describes the design, construction, operation and use of the DECL (Decade PLL) module. The module has both a Phase Locked Loop (PLL) frequency multiplier and a frequency divider to produce various output frequencies that are based on an input....
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The following describes the design, construction, operation and use of the DECUS divider module. Photo 2 shows a top view of the module and Photo 3 shows the bottom. The primary use of the module is to condition the 10 megahertz (MHz) signal from a rubidium....
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The following describes the design, construction, operation and use of the Multiple Target Developent System (MUTS). The MUTS consists of a Target board (Target) that can connect to a Silicon Laboratories (SL) Debug Adaptor to program the Target board with....
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The PRUBY module that provides a PLL interface for rubidium frequency references such as the LPRO-101 and FRS-C products manufactured by EFRATOM Ball, Inc. The module conditions the ten megahertz (MHz) signal from the reference and provides both a square....
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The amplifier can be used in a number of projects to buffer and amplify outputs from devices such as Direct Digital Synthesizer (DDS) chips. The board was initially produced to amplify the output of the 9833 DDS chip. The board was also intended for Amateur....
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With the world`s non-renewable resources being consumed at an alarming rate, it`s no surprise that when the new curriculum was released, 2 ½ years ago, the word `environmental` appeared in the key concepts. The programme of study goes on to add that this....
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The 555 astable board uses a 555 timer in its astable configuration. This means that it outputs a square wave or a series of high and low signals. The speed that the signal goes high and low is set by the capacitor C1 and variable resistor R3. The board is....
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The thought of going to 24 GHz was far from my mind back in the summer of 2002. We had just come back from the Central States VHF convention in Madison Wisconsin where I had done a bit of chatting about it, but nothing serious. With Jenna just being born, I....
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Emphasis on the high bands (902 thru 10 GHz) had been a priority here at ARS KMGT for the last few years. The low bands were in pretty good shape, so not much other than standard maintenance was needed there. However, improvements to the microwave station....
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Port 1 of the controller (AT89C4051) is used as the data lines for the LCD (starting from pin 7- pin14 of LCD). here i am using a 16 x 2 lines LCD display. In the first line, I`ll display "DAY" and "DATE", in the second line, i am displaying "TIME" with....
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This ISP Programmer can be used either for in-system programming or as a stand-alone spi programmer for Atmel ISP programmable devices. The programming interface is compatible to STK200 ISP programmer hardware so the users of STK200 can also use the software....
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This LCD terminal provide two modes of operation by selecting jumper J1. When J1 is open the terminal operate as a normal ascii display terminal, when J1 is closed the terminal displays the input serial data in hexadecimal format. This mode is useful for....
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Easy build and use, the general purpose Big LED with SPI serial interfacing. Expandable for multiple digits but still uses only three wires for receiving data from any uC boards. The circuit uses a serial-in-parallel out shift register, 74HC595 for receiving....
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This circuit provides a short circuit protected power supply from PC 12V supply voltage. This is particularly handy when working with PC interfacing projects. Fig-1 shows the circuit diagram of the complete power supply. The necessary 12V supply voltage is....
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This self powered interface circuit electrically isolates the TxD and RxD lines from the PC serial port and protect the PC from direct connection to hazardous voltages. The isolator is intended to provide electrical isolation between a computer and the....
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This SPI Flash Programmer can be used either for in-system programming or as a stand-alone serial flash programmer for the Atmel SPI programmable devices. The programmer hardware interface is controlled by the PC parallel port and the parallel port control....
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Basic circuit of using L293 formsan H-Bridge Driver is shown in Figure 1. As shown for such inductive loadas DC motor, external diodes for suppressing back EMF must be connected. The MiniBoard uses L293D instead, the L293D has internal diodes,....
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Build your own a personal data logger for recording analog signal. The MiniLOGGER provides 8-channel analog input(-99mV to +999mV), 1-channel pulse input, battery backup 256kB SRAM, Real-time Clock, and RS232C. Start/Stop recording can be made by MANUAL....