Top Circuits Page 263
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The circuit below is a one-shot multivibrator. One shot multivibrator is also known as monostable multivibrator, or timer. The main function of such circuit is....
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Using the circuit depicted in the schematic diagram below we can monitor the heart pulses of patient. This circuit buffer and amplify the heart pulses, and the....
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An oscillator can be built using LC (inductor-capacitor) tank circuit. When we vary the capacity of the capacitor in LC tank circuit then the frequency of the....
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Most cases of infra-red remote control failure can be detected by detecting the absence of the pulsed transmitted infra red light. It`s very rare that the....
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This relay circuit is controlled by almost any type of infrared remote controller. This circuit works on assumption that almost all remote controller use high....
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Ultrasonic sound wave can be generated using electronic circuit. This simple electronic circuit can generate an ultrasonic wave with frequency range of 12 to....
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A signal conditioner for pH meter probe is required to have high input impedance. The signal conditioning of the pH meter probe is done by providing a buffer....
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With the help of high gain high impedance operational amplifier, we can build a long time delay with resistor-capacitor (RC) circuit since it allow high....
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Balance indicator for power supply show if a symmetric power supply is really symmetric or not. With two comparator pairs from a LM339N quad comparator we....
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At high speed, visually checking your speedometer to keep under maximum speed can be dangerous. It will be much safer if we put an audio alarm system to give a....
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This is a flash triggered (photo-driven) circuit which produce a pulse with constant predetermined wide. This circuit can be used to control any device which....
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A DC to DC converter is needed for a board that only has +5V supply but have to provide dual-polarity supplies for few device such as op-amp or some DAC. Using....
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RS flip-flop, or reset-set flip flop, is a kind of stable multivibrator with two input, namely reset and set. The output will be at one of two stable states,....
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A signal averager circuit can be formed by an amplifier and active signal rectifier, which is implemented using two operational amplifiers in this circuit. The....
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We can do a step-up conversion without using transformer. Using this circuit, a 5V DC source can be converted into 15V. Please note that there is no power gain....
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How can television modulator be small and simple like this? First, it uses integrated circuit, and the second, any TV modulator is nothing more than amplitude....
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This application note describes the addition of a quad serial controller to the EB675001 Module. A multi source quad Universal Asyncronous Reciver and Transmitter (UART), 16554 type, was selected to ease implementation and sourcing of components. The RS232....
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The user CPLD is only used in this design to interface the LCD module and is the same code as used in the Attaching an LCD module to the EB675001DIP application note. CLinux was used to communicate with the GPS module. Communication is simply achieved using....
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This application note describes creating a dumb framebuffer with PAL composite TV output for the EB675001DIP. The design uses a minimal number of additional components to achieve this display. The user CPLD is used to provide all control and timing logic....
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It is sometimes necessary to monitor a device that generates a relatively short pulse to indicate a change of status. If the duration of the input signal is too short, the RFC-1/B may not have time to capture the pulse and respond appropriately. The RFC-1/B....
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This pre-amplifier can be drived directly from the DAC. ..
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This circuit detects the dial tone from a telephone line and decodes the keypad pressed on the remote telephone. The dial tone we heard when we pick up the phone set is call Dual Tone Multi-Frequency, DTMF in short. The name was given because the tone that....
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Now, let`s re-examine the function of the TRIS registers. The TRISA and TRISB registers control the direction of data transfer on each pin of Port A and Port B, respectively. The easy way to remember the TRIS register settings is to match the numbers 0 and 1....
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(This circuit first appeared in "The Braille Technical Press", edited by Robert W. Gunderson, in 1955. Gunderson, W2JIO, designed this "gimmick" to read transmitter meters. It appeared many times since over a 20-year period, included even in commercial aids....
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[The following circuit is adapted from battery monitors and testers published in The Smith-Kettlewell Technical File (SKTF). The first appearance of this system was "The Smith-Kettlewell Battery Tester, Where Silence is Golden", SKTF, Volume 11, No. 1,....
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How a cutt of a fader is differnet form a transform What does skratch tricks have to do with the fader function The cut on a fader is completely different from a transform. It isn`t an instant on/off but a sloped cut in perhaps anywhere from a few hundred....
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This area shows the construction and testing of a new half-wave (dual) Tesla coil. This type of coil has two secondaries driven by a single tank circuit. The design shown here is a small and rather in-efficient dual coil constructed from scrap parts for....
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This area shows the construction and testing of a medium to large class Tesla coil. In this section, the previous coils were dismantled and a new larger coil, with a secondary over 6 inches, was redesigned and constructed for maximum efficiency at a power if....
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The momentary hold relay board and the acc delay module are a couple things I engineered. The momentary hold relay board is to power on the gps unit and the tablet, it replaces the need for you to push a button. The acc delay module is for my older amp. It....
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The threaded drive rod was made from standard 5/16 inch Whitworth threaded rod (18 TPI), only because this was to hand. M8 metric thread could have been used. The radius of the curve in the drive rod (which must be equal to the distance between the hinge and....
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The RF engineer sometimes has to look for an instrument that will check a low frequency quartz crystal unit reliably and rapidly. This is a difficult piece of equipment to find and the engineer often has to consult an electronic circuits handbook for the....
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Restore the older style of telephones which used a pair of gongs to annunciate an incoming call, AND long to hear the nostalgic peel of those bells Presented here is a design for a "Telephone Ring Generator" which when connected to a suitable telephone will....
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This is a charger circuit for both NiCd and NiMh Batteries. Some time ago I aquired an old commercial handheld-TRX which was powered by a 12 Volt NiCd-Battery pack (10 Button Cells each having a capacity of 280mAh). In fact this (at least 10 year) old....
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This is a switch selectable dual output "re-hashed" version of my previous (2007) design, and uses a field programmed EPROM for generating both versions of the ringing sequence. AC mains is stepped down to about 10 v AC and fed to the familiar bridge....
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If you look into the bottom of a valve you will see the wires from each electrode and you can see the valve base pins to which they are connected. For this reason I will not give any valve data or pin-outs. These are widely available from other sources and....
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Make a basic RF oscillator. The circuit is ridiculously simple, so I will skip all the complicated maths and make component selection simple by using calculators. Let us assume I want an oscillator for 7MHz. The circuit looks like this: The first transistor....
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My particular favourite was the MC145152-2 that could be programmed with DIP switches, a diode matrix, or even a pair of EPROM look-up tables. But sadly, those days are over. The MC145152-2 costs about US$30, if you can find a supplier. Today we need to use....
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It is a programable frequency multiplier, usually using digital logic integrated circuits. The synthesizer is aranged to multiply a reference frequency by a programable amount to achieve just about any frequency you want. If, for example you had a reference....
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This turned out to be quite an interesting project. It all began as a project for a paying customer, but I found that the circuit had quite a lot of advantages over previous similar projects. It is basically an inverter for converting power from 12v DC to....
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If you have the time and money then make this plate bigger, if possible. 5-meters would be ideal for a home base. Similar to the system used in modern aviation where an antenna array modulates the phase of an incoming signal. The commercial system is known....
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This transmitter is very stable and will deliver up to seven watts of power with the components and tubes shown. Do not be put-off by valves as they are VERY easy to work with and it seems that there are quite a few valves around. Because no-one wants these....
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I am feeding that box with 12 volts, and it has a sequencer board, some external relays to drive the coaxial relays, preamp and the amplifier. As you can see, this sequencer board has some DIL relays, they are only intended to drive external relays that....
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A 52 MHz third overtone crystal is typically 30 ohms at its series resonance according to manufacturer specifications. The crystals used for the prototypes have nearly ten times lower series resistance but they were very expensive. An oscillator can be seen....
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The RF amplifier is similar to the one used in the 2. 5MHz amplifier. At a frequency of 10MHz the capacitances of a power MOS-FET become significant. Noiseless feedback by the use of transformers is no longer straightforward. Intermodulation and overtones....
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The RF amplifiers use noiseless feedback through the drain-gate capacitance with an inductor in the source lead to provide the necessary 90 degree phase shift between gate voltage and channel current. The first RF amplifier gives about 4dB gain with a noise....
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The RF amplifier uses noiseless feedback through the drain-gate capacitance with an inductor in the source lead to provide the necessary 90 degree phase shift between gate voltage and channel current...
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A 10 MHz crystal is typically 4 ohms at its series resonance and 40 kiloohms at its parallell resonance. To get low sideband noise the power dissipated in the crystal has to be reasonably large, the design used here dissipates 0. 2mW in the crystal, 7mA and....
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By use of transformers one can apply both voltage feedback and current feedback. There was an article in Ham Radio november 1979 by DJ2LR Ulrich Rohde giving details about this circuit. For the 2. 5MHz to audio converter the transformation ratio from drain....
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The design is based on the TubeHobby and is the power supply used in their NC2. I built this very kit as my first nixie tube project, and you can find a review of this excellent kit in the reviews section of my blog. The circuit is a switch-mode power supply....
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After building so many Nixie Tube Clocks from the Internet, I finally decided to design my own. My clock uses IN-12 Nixie Tubes and an 8-core Propeller Microcontroller. The Propeller may a be a bit of overkill for the task, but it`s the microcontroller that....
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The schematic diagram below shows a simple trivial low-cost 12 volt DC 50W off-line SMPS switching power supply circuit. It can be used for DIY home projects or to learn operation of flyback converters. This PSU can work over a universal input AC line range....
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All electronic systems and equipment regardless of their size or function have one thing in common: they all need a power supply unit (PSU) that converts input voltage into a voltage or voltages suitable for their circuits. The most common type of today`s....
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A sample robot, using parts from VCRs and bought only the minimum necessary to make the simplest robot I could think of. At the time I was using the Nemesis microcontroller, produced by Kronos Robotics, however this was not a good choice for Romania, because....
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This tutorial details the construction of a simple and low cost robot. The robot is mainly a line follower but can also be used as a photovore, a photophobe, and obstacle avoider!And all this for less than 40$. The best part is that the robot does not use....
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This device has been designed as an example application of an expandable system of modules for building mobile robots following the standards set out in the discussion on the Society Of Robots forum. These modules can be connected to each other using an i2c....
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The brain of the robot is made of Atmel Tiny2313 microcontroller. This MCU has a cool feature called In-System Programming which can be used to program memories of the MCU with almost-no-cost programmer. I used simple programmer which connects to parallel....
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In this project we`ll be using the ATMEGA16 @16MHz. But as every project. it must have something special, something to be able to look different from other. But what I `ve seen many robots with photosensors (photovore, photophobe), many linefollowers, many....
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The UART, or Universal Asynchronous Receiver / Transmitter, is a feature of your microcontroller useful for communicating serial data (text, numbers, etc. ) to your PC. The device changes incoming parallel information (within the microcontroller/PC) to....
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The most important schematic to know, one that is almost always required for every robot whether you`re a beginner or advanced, is a circuit to control your robots` power source. You cannot just hook up a battery directly to everything and expect it to work.....
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Current sensing is as it says - sensing the amount of current in use by a particular circuit or device. If you want to know the amount of power being used for any robot component, current sensing is the way to go. Current sensing is not a typical application....
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This circuit has a long and storied history - starting with an idea by Rich Piotter, then being honed and simplified by Wilf Rigter and Bruce Robinson. The final result does not show the necessary motor drivers (usually H-bridge based), but here`s the....
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The P5 design uses only eight 74HC/AC240 chips which are all octal inverting buffers. Each 74HC/AC240 chip has two groups of four inverters each controlled by a tri-state enable pin (pin 1 and 19). The 74AC240 chips (U1-U5) are used as H-bridge style motor....
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There is an advantage in using continuously active PWM signals. The main reason is that the asynchronous frequencies of the PWM core and microcore can sometimes result in a forshortened PWM pulse. The Sevo reconizes this as a command for a new positions and....
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I had always assumed that dynamic braking would be most effective at higher speeds. However, actual tests using a Faulhaber (micro mo) gear motor showed that the brake would hold a motor almost stationary. These gearmotors are so well made that I can turn....
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Altogether it will cost about US$ 10 and much room on my circuit board. The design is really great but i don`t have to room for it and i like to spend less. You can drop all off the transistors and resistors if your motors don`t drain too much current. You....
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The Zero Volt Diode (ZVD) is a circuit useful in a variety of applications including solar chargers of all types. It is a novel circuit in which a power MOSFET acts like a very low voltage drop diode that switches state at 0V and which is used to conduct....
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The MC34164 VS used in the Chloroplast SE is different in one respect from the 1381 VS (used in the VTSE and 1381 SEs) in that the MC34164 has an "open drain" output which requires a pull up resistor to the positive supply for the output to go positive. The....
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If you had time to experiment with the ALF type SE circuit you may have discovered some of its shortcomings with regard to a Power Smart Head adaptation. The problem is that HCMOS gates are power hungry when used as SE voltage comparators when the analog....
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A micro power solar engine has been a goal since my introduction to BEAM Robotics. I believe that if there wasn`t one before, I there is one now. What I`m presenting to you looks very similar to one of the circuits found in Steven Bolt`s web pages. As you....
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The all-transistor T3SE works much like a conventional SE: like the Tritium, it fires when the charging current drops below the minimum and after the circuit triggers, positive feedback is used to latch the circuit, resetting at a fixed voltage on the main....
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A power inverter converts DC power or direct current to standard AC power or alternating current. The following schematic shows a 12V power inverter Circuit Diagram...
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The giant (by radio control standards) servos above are shown adjacent to a Nokia 3310 mobile phone to give an idea of the scale. The arms are 12cm long - perfect for lifting a bank of solar panels (wing). Our local Model Aerodrome in Seaside Road,....
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Here is another little circuit I designed for radiation logging purposes. It is based on an Atmel 168 Microcontroller and a small and precise RTC device called RV3029. I also used an AT45DB41 Dataflash for this Circuit, as I had the sourcecode for....
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Several easy modifications for a Dataq DI-194RS and DI-154RS. There are at least two different styles: the kind that come packaged (shown) and the kind that come as an unpackaged PCB. The unpackaged ones are what you get when you are fortunate enough to get....
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This circuit is used to trigger a camera`s electronic shutter circuit when a flash of lightning is present. This circuit would also work for photographing fireworks displays or other events involving flashes of light. In a nutshell, the photo darlington....
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The FM broadcast band was moved immediately after World War II from its original spot just below 50 Mc to the present 88-108 Mc band. Hallicrafters was one company to offer receiving converters for those who had the old FM radio sets. The offerings included....
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Broadcast band frequency modulation (FM) radio was invented to solve existing problems with noise and fidelity on the amplitude modulation (AM) broadcast band. Thus, the first FM receivers were quite complex in design, employing a superheterodyne converter,....
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This is the unexpurgated, pre-edited version of the article "Improved Anode-Circuit Parasitic-Suppression For Modern Amplifier-Tubes" that appeared on page 36 in the October 1988 issue of QST. A more recent treatment of the subject appeared in the September....
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Today, it is by far the most common preamp tube used for electric guitar amplification and there is an almost overwhelming supply of current production options to choose from. The purpose of this comparison is simply to provide guitar players with a frame of....
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It provides a fully featured commentator position and a line-level input. The unit has an individual commentator output, with an additional output providing a mix of commentator and line input audio. A limit indicator on the main panel shows when the....
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The CM-CU21 is a high quality, portable Commentator Unit. Its sturdy construction and flexibility of features make it suitable for use in a wide variety of environments. It provides two fully featured commentator positions and a third guest position that can....
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The TX audio cable can be a little more complicated then the RX audio cable. Normally, the TX audio cable must have a circuit to attenuate the voltage leaving the sound card`s LINE OUT jack, otherwise the radio`s transmit circuit will be overdriven. Note:....
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A tube commonly used as a tuning indicator in old radios. I had to try them out in my amps. So I plopped together a quick video to see the dramatic and cool visual effect. I will probably tweak some values but overall I am very happy with the visual effect.....
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Most of the devices used in amplifier output stages are intrinsically seriously non-linear; the worst of all are transistors (both bipolar and FET) which are almost always used inside a global feedback loop for this very reason. Even tetrode and pentode....
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This is a distillation of my " design notes ", with more practical details as I move along with the construction, and (in due course) some pictures. Right at the moment I`m using it as a kind of progress report for myself - it`s a mixture of immediate plans....
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This setup is quite messy in terms of wires, so I`ve decided to remove both from their respective housings and place them in a nice, custom-built box. Right, so while I`m about to do that, aren`t there any other goodies toadd, like a VU meter and volume....
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Interferometer is best used in calculating the index of refraction of gasses and transparent matter (i. e. air and glass). Doing so requires counting each interference circle one by one. As a matter of fact, getting a precise measurement requires counting up....
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The analog interface is a very simple analog to digital converter which accepts the analog video output of the RF/IF board and puts it into a form that can be read by a PC Games port. The joystick input of the games port essentially converts a resistance in....
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Nothing wrong at all with that setup IMO. I`ve an (older) Peltor FMT15 amp in my Golf. Works awesome for 2 Peltor headsets. The issue is mixing Peltor & Terraphone headsets/amps. All (3) of the cars I`ve co-driven in this year have Terraphone amps. They`ve....
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This time it is using the IC made by National Semiconductor the LM2662M. This is a direct replacement for the MAX1044 just it is a surface mount part (so it is a lot smaller). I have also changed the main voltage regulator to the LM7805ACT, more on this....
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The FT-736R is a V/UHF all mode transceiver. A picture of the FT736R can be seen in figure 1. This article will show how you can modify the AGC (Automatic Gain Control) circuit to disable it. When you are doing radio astronomy it ’s vital to be able to....
The circuit below is a one-shot multivibrator. One shot multivibrator is also known as monostable multivibrator, or timer. The main function of such circuit is....
Using the circuit depicted in the schematic diagram below we can monitor the heart pulses of patient. This circuit buffer and amplify the heart pulses, and the....
An oscillator can be built using LC (inductor-capacitor) tank circuit. When we vary the capacity of the capacitor in LC tank circuit then the frequency of the....
Most cases of infra-red remote control failure can be detected by detecting the absence of the pulsed transmitted infra red light. It`s very rare that the....
This relay circuit is controlled by almost any type of infrared remote controller. This circuit works on assumption that almost all remote controller use high....
Ultrasonic sound wave can be generated using electronic circuit. This simple electronic circuit can generate an ultrasonic wave with frequency range of 12 to....
A signal conditioner for pH meter probe is required to have high input impedance. The signal conditioning of the pH meter probe is done by providing a buffer....
With the help of high gain high impedance operational amplifier, we can build a long time delay with resistor-capacitor (RC) circuit since it allow high....
Balance indicator for power supply show if a symmetric power supply is really symmetric or not. With two comparator pairs from a LM339N quad comparator we....
At high speed, visually checking your speedometer to keep under maximum speed can be dangerous. It will be much safer if we put an audio alarm system to give a....
This is a flash triggered (photo-driven) circuit which produce a pulse with constant predetermined wide. This circuit can be used to control any device which....
A DC to DC converter is needed for a board that only has +5V supply but have to provide dual-polarity supplies for few device such as op-amp or some DAC. Using....
RS flip-flop, or reset-set flip flop, is a kind of stable multivibrator with two input, namely reset and set. The output will be at one of two stable states,....
A signal averager circuit can be formed by an amplifier and active signal rectifier, which is implemented using two operational amplifiers in this circuit. The....
We can do a step-up conversion without using transformer. Using this circuit, a 5V DC source can be converted into 15V. Please note that there is no power gain....
How can television modulator be small and simple like this? First, it uses integrated circuit, and the second, any TV modulator is nothing more than amplitude....
This application note describes the addition of a quad serial controller to the EB675001 Module. A multi source quad Universal Asyncronous Reciver and Transmitter (UART), 16554 type, was selected to ease implementation and sourcing of components. The RS232....
It is sometimes necessary to monitor a device that generates a relatively short pulse to indicate a change of status. If the duration of the input signal is too short, the RFC-1/B may not have time to capture the pulse and respond appropriately. The RFC-1/B....
This pre-amplifier can be drived directly from the DAC. ..
This circuit detects the dial tone from a telephone line and decodes the keypad pressed on the remote telephone. The dial tone we heard when we pick up the phone set is call Dual Tone Multi-Frequency, DTMF in short. The name was given because the tone that....
Now, let`s re-examine the function of the TRIS registers. The TRISA and TRISB registers control the direction of data transfer on each pin of Port A and Port B, respectively. The easy way to remember the TRIS register settings is to match the numbers 0 and 1....
(This circuit first appeared in "The Braille Technical Press", edited by Robert W. Gunderson, in 1955. Gunderson, W2JIO, designed this "gimmick" to read transmitter meters. It appeared many times since over a 20-year period, included even in commercial aids....
[The following circuit is adapted from battery monitors and testers published in The Smith-Kettlewell Technical File (SKTF). The first appearance of this system was "The Smith-Kettlewell Battery Tester, Where Silence is Golden", SKTF, Volume 11, No. 1,....
How a cutt of a fader is differnet form a transform What does skratch tricks have to do with the fader function The cut on a fader is completely different from a transform. It isn`t an instant on/off but a sloped cut in perhaps anywhere from a few hundred....
This area shows the construction and testing of a new half-wave (dual) Tesla coil. This type of coil has two secondaries driven by a single tank circuit. The design shown here is a small and rather in-efficient dual coil constructed from scrap parts for....
This area shows the construction and testing of a medium to large class Tesla coil. In this section, the previous coils were dismantled and a new larger coil, with a secondary over 6 inches, was redesigned and constructed for maximum efficiency at a power if....
The momentary hold relay board and the acc delay module are a couple things I engineered. The momentary hold relay board is to power on the gps unit and the tablet, it replaces the need for you to push a button. The acc delay module is for my older amp. It....
The threaded drive rod was made from standard 5/16 inch Whitworth threaded rod (18 TPI), only because this was to hand. M8 metric thread could have been used. The radius of the curve in the drive rod (which must be equal to the distance between the hinge and....
The RF engineer sometimes has to look for an instrument that will check a low frequency quartz crystal unit reliably and rapidly. This is a difficult piece of equipment to find and the engineer often has to consult an electronic circuits handbook for the....
Restore the older style of telephones which used a pair of gongs to annunciate an incoming call, AND long to hear the nostalgic peel of those bells Presented here is a design for a "Telephone Ring Generator" which when connected to a suitable telephone will....
This is a charger circuit for both NiCd and NiMh Batteries. Some time ago I aquired an old commercial handheld-TRX which was powered by a 12 Volt NiCd-Battery pack (10 Button Cells each having a capacity of 280mAh). In fact this (at least 10 year) old....
This is a switch selectable dual output "re-hashed" version of my previous (2007) design, and uses a field programmed EPROM for generating both versions of the ringing sequence. AC mains is stepped down to about 10 v AC and fed to the familiar bridge....
If you look into the bottom of a valve you will see the wires from each electrode and you can see the valve base pins to which they are connected. For this reason I will not give any valve data or pin-outs. These are widely available from other sources and....
Make a basic RF oscillator. The circuit is ridiculously simple, so I will skip all the complicated maths and make component selection simple by using calculators. Let us assume I want an oscillator for 7MHz. The circuit looks like this: The first transistor....
My particular favourite was the MC145152-2 that could be programmed with DIP switches, a diode matrix, or even a pair of EPROM look-up tables. But sadly, those days are over. The MC145152-2 costs about US$30, if you can find a supplier. Today we need to use....
It is a programable frequency multiplier, usually using digital logic integrated circuits. The synthesizer is aranged to multiply a reference frequency by a programable amount to achieve just about any frequency you want. If, for example you had a reference....
This turned out to be quite an interesting project. It all began as a project for a paying customer, but I found that the circuit had quite a lot of advantages over previous similar projects. It is basically an inverter for converting power from 12v DC to....
If you have the time and money then make this plate bigger, if possible. 5-meters would be ideal for a home base. Similar to the system used in modern aviation where an antenna array modulates the phase of an incoming signal. The commercial system is known....
This transmitter is very stable and will deliver up to seven watts of power with the components and tubes shown. Do not be put-off by valves as they are VERY easy to work with and it seems that there are quite a few valves around. Because no-one wants these....
I am feeding that box with 12 volts, and it has a sequencer board, some external relays to drive the coaxial relays, preamp and the amplifier. As you can see, this sequencer board has some DIL relays, they are only intended to drive external relays that....
A 52 MHz third overtone crystal is typically 30 ohms at its series resonance according to manufacturer specifications. The crystals used for the prototypes have nearly ten times lower series resistance but they were very expensive. An oscillator can be seen....
The RF amplifier is similar to the one used in the 2. 5MHz amplifier. At a frequency of 10MHz the capacitances of a power MOS-FET become significant. Noiseless feedback by the use of transformers is no longer straightforward. Intermodulation and overtones....
The RF amplifiers use noiseless feedback through the drain-gate capacitance with an inductor in the source lead to provide the necessary 90 degree phase shift between gate voltage and channel current. The first RF amplifier gives about 4dB gain with a noise....
The RF amplifier uses noiseless feedback through the drain-gate capacitance with an inductor in the source lead to provide the necessary 90 degree phase shift between gate voltage and channel current...
A 10 MHz crystal is typically 4 ohms at its series resonance and 40 kiloohms at its parallell resonance. To get low sideband noise the power dissipated in the crystal has to be reasonably large, the design used here dissipates 0. 2mW in the crystal, 7mA and....
By use of transformers one can apply both voltage feedback and current feedback. There was an article in Ham Radio november 1979 by DJ2LR Ulrich Rohde giving details about this circuit. For the 2. 5MHz to audio converter the transformation ratio from drain....
The design is based on the TubeHobby and is the power supply used in their NC2. I built this very kit as my first nixie tube project, and you can find a review of this excellent kit in the reviews section of my blog. The circuit is a switch-mode power supply....
After building so many Nixie Tube Clocks from the Internet, I finally decided to design my own. My clock uses IN-12 Nixie Tubes and an 8-core Propeller Microcontroller. The Propeller may a be a bit of overkill for the task, but it`s the microcontroller that....
The schematic diagram below shows a simple trivial low-cost 12 volt DC 50W off-line SMPS switching power supply circuit. It can be used for DIY home projects or to learn operation of flyback converters. This PSU can work over a universal input AC line range....
All electronic systems and equipment regardless of their size or function have one thing in common: they all need a power supply unit (PSU) that converts input voltage into a voltage or voltages suitable for their circuits. The most common type of today`s....
A sample robot, using parts from VCRs and bought only the minimum necessary to make the simplest robot I could think of. At the time I was using the Nemesis microcontroller, produced by Kronos Robotics, however this was not a good choice for Romania, because....
This tutorial details the construction of a simple and low cost robot. The robot is mainly a line follower but can also be used as a photovore, a photophobe, and obstacle avoider!And all this for less than 40$. The best part is that the robot does not use....
This device has been designed as an example application of an expandable system of modules for building mobile robots following the standards set out in the discussion on the Society Of Robots forum. These modules can be connected to each other using an i2c....
The brain of the robot is made of Atmel Tiny2313 microcontroller. This MCU has a cool feature called In-System Programming which can be used to program memories of the MCU with almost-no-cost programmer. I used simple programmer which connects to parallel....
In this project we`ll be using the ATMEGA16 @16MHz. But as every project. it must have something special, something to be able to look different from other. But what I `ve seen many robots with photosensors (photovore, photophobe), many linefollowers, many....
The UART, or Universal Asynchronous Receiver / Transmitter, is a feature of your microcontroller useful for communicating serial data (text, numbers, etc. ) to your PC. The device changes incoming parallel information (within the microcontroller/PC) to....
The most important schematic to know, one that is almost always required for every robot whether you`re a beginner or advanced, is a circuit to control your robots` power source. You cannot just hook up a battery directly to everything and expect it to work.....
Current sensing is as it says - sensing the amount of current in use by a particular circuit or device. If you want to know the amount of power being used for any robot component, current sensing is the way to go. Current sensing is not a typical application....
This circuit has a long and storied history - starting with an idea by Rich Piotter, then being honed and simplified by Wilf Rigter and Bruce Robinson. The final result does not show the necessary motor drivers (usually H-bridge based), but here`s the....
The P5 design uses only eight 74HC/AC240 chips which are all octal inverting buffers. Each 74HC/AC240 chip has two groups of four inverters each controlled by a tri-state enable pin (pin 1 and 19). The 74AC240 chips (U1-U5) are used as H-bridge style motor....
There is an advantage in using continuously active PWM signals. The main reason is that the asynchronous frequencies of the PWM core and microcore can sometimes result in a forshortened PWM pulse. The Sevo reconizes this as a command for a new positions and....
I had always assumed that dynamic braking would be most effective at higher speeds. However, actual tests using a Faulhaber (micro mo) gear motor showed that the brake would hold a motor almost stationary. These gearmotors are so well made that I can turn....
Altogether it will cost about US$ 10 and much room on my circuit board. The design is really great but i don`t have to room for it and i like to spend less. You can drop all off the transistors and resistors if your motors don`t drain too much current. You....
The Zero Volt Diode (ZVD) is a circuit useful in a variety of applications including solar chargers of all types. It is a novel circuit in which a power MOSFET acts like a very low voltage drop diode that switches state at 0V and which is used to conduct....
The MC34164 VS used in the Chloroplast SE is different in one respect from the 1381 VS (used in the VTSE and 1381 SEs) in that the MC34164 has an "open drain" output which requires a pull up resistor to the positive supply for the output to go positive. The....
If you had time to experiment with the ALF type SE circuit you may have discovered some of its shortcomings with regard to a Power Smart Head adaptation. The problem is that HCMOS gates are power hungry when used as SE voltage comparators when the analog....
A micro power solar engine has been a goal since my introduction to BEAM Robotics. I believe that if there wasn`t one before, I there is one now. What I`m presenting to you looks very similar to one of the circuits found in Steven Bolt`s web pages. As you....
The all-transistor T3SE works much like a conventional SE: like the Tritium, it fires when the charging current drops below the minimum and after the circuit triggers, positive feedback is used to latch the circuit, resetting at a fixed voltage on the main....
A power inverter converts DC power or direct current to standard AC power or alternating current. The following schematic shows a 12V power inverter Circuit Diagram...
The giant (by radio control standards) servos above are shown adjacent to a Nokia 3310 mobile phone to give an idea of the scale. The arms are 12cm long - perfect for lifting a bank of solar panels (wing). Our local Model Aerodrome in Seaside Road,....
Here is another little circuit I designed for radiation logging purposes. It is based on an Atmel 168 Microcontroller and a small and precise RTC device called RV3029. I also used an AT45DB41 Dataflash for this Circuit, as I had the sourcecode for....
Several easy modifications for a Dataq DI-194RS and DI-154RS. There are at least two different styles: the kind that come packaged (shown) and the kind that come as an unpackaged PCB. The unpackaged ones are what you get when you are fortunate enough to get....
This circuit is used to trigger a camera`s electronic shutter circuit when a flash of lightning is present. This circuit would also work for photographing fireworks displays or other events involving flashes of light. In a nutshell, the photo darlington....
The FM broadcast band was moved immediately after World War II from its original spot just below 50 Mc to the present 88-108 Mc band. Hallicrafters was one company to offer receiving converters for those who had the old FM radio sets. The offerings included....
Broadcast band frequency modulation (FM) radio was invented to solve existing problems with noise and fidelity on the amplitude modulation (AM) broadcast band. Thus, the first FM receivers were quite complex in design, employing a superheterodyne converter,....
This is the unexpurgated, pre-edited version of the article "Improved Anode-Circuit Parasitic-Suppression For Modern Amplifier-Tubes" that appeared on page 36 in the October 1988 issue of QST. A more recent treatment of the subject appeared in the September....
Today, it is by far the most common preamp tube used for electric guitar amplification and there is an almost overwhelming supply of current production options to choose from. The purpose of this comparison is simply to provide guitar players with a frame of....
It provides a fully featured commentator position and a line-level input. The unit has an individual commentator output, with an additional output providing a mix of commentator and line input audio. A limit indicator on the main panel shows when the....
The CM-CU21 is a high quality, portable Commentator Unit. Its sturdy construction and flexibility of features make it suitable for use in a wide variety of environments. It provides two fully featured commentator positions and a third guest position that can....
The TX audio cable can be a little more complicated then the RX audio cable. Normally, the TX audio cable must have a circuit to attenuate the voltage leaving the sound card`s LINE OUT jack, otherwise the radio`s transmit circuit will be overdriven. Note:....
A tube commonly used as a tuning indicator in old radios. I had to try them out in my amps. So I plopped together a quick video to see the dramatic and cool visual effect. I will probably tweak some values but overall I am very happy with the visual effect.....
Most of the devices used in amplifier output stages are intrinsically seriously non-linear; the worst of all are transistors (both bipolar and FET) which are almost always used inside a global feedback loop for this very reason. Even tetrode and pentode....
This is a distillation of my " design notes ", with more practical details as I move along with the construction, and (in due course) some pictures. Right at the moment I`m using it as a kind of progress report for myself - it`s a mixture of immediate plans....
This setup is quite messy in terms of wires, so I`ve decided to remove both from their respective housings and place them in a nice, custom-built box. Right, so while I`m about to do that, aren`t there any other goodies toadd, like a VU meter and volume....
Interferometer is best used in calculating the index of refraction of gasses and transparent matter (i. e. air and glass). Doing so requires counting each interference circle one by one. As a matter of fact, getting a precise measurement requires counting up....
The analog interface is a very simple analog to digital converter which accepts the analog video output of the RF/IF board and puts it into a form that can be read by a PC Games port. The joystick input of the games port essentially converts a resistance in....
Nothing wrong at all with that setup IMO. I`ve an (older) Peltor FMT15 amp in my Golf. Works awesome for 2 Peltor headsets. The issue is mixing Peltor & Terraphone headsets/amps. All (3) of the cars I`ve co-driven in this year have Terraphone amps. They`ve....
This time it is using the IC made by National Semiconductor the LM2662M. This is a direct replacement for the MAX1044 just it is a surface mount part (so it is a lot smaller). I have also changed the main voltage regulator to the LM7805ACT, more on this....
The FT-736R is a V/UHF all mode transceiver. A picture of the FT736R can be seen in figure 1. This article will show how you can modify the AGC (Automatic Gain Control) circuit to disable it. When you are doing radio astronomy it ’s vital to be able to....
