Top Circuits Page 120
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Four button RF remote is used to turn ON / OFF four different devices independently. Any of the four outputs can be configured to work independently in either toggle or momentary mode. Outputs are buffered by BC549 NPN transistors and can drive low voltage....
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This is simple 3-digits digital volt meter.PIC16F676 used to read analog signal(voltage) and display the value on 3-digits 7-segment. You can apply similar principles to measure DC current with parallel R shunt..
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As shown in the schematic, temperature sensor of our electronic thermometer is LM35DZ. There are some kinds of LM35 IC, since it is cheap and easy to find we used LM35DZ in our project. It measures from 0?C to 100?C with a very linear output graph.For one....
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The amplifier has exactly the same architecture as TX500 with the difference that TX300 has only one stage variable VHF amplifier. It is a cute schematic that was made for all of you who wanted something even simpler than TX500 and with not as many necessary....
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The TX500 is a simple to build 500mW FM Transmitter. It consists of three blocks; modulator / oscillator, two stage 500mW VHF amplifier and LED based power meter. The TX500 allows to transmit audio signals to FM band at frequencies from 88 MHz to 108 MHz.....
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This tiny receiver is not much bigger than an AA cell. It is powered off two LR44 button cells, which are expensive and I assume wouldn`t last terribly long. I`ll be on the lookout for LR44`s at the markets and $2 shops now that I`ve got this radio! As with....
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This project is a FM Radio based on TDA7000 and LM386 integrated circuits. What is unusual about TDA7000 IC is how it operates. It is a proper FM superhet receiver, with the usual local oscillator, mixer, IF amplifier, limiter, and phase detector. The....
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Here is the circuit diagram of the simple FM transmitter using a transistor. Great performance or range is not guaranteed here, because this is an elementary design. General purpose radio frequency transistor BF 494 (Q1) is used here for obtaining FM....
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This FM transmitter is about the simplest and most basic FM transmitter it is possible to build and have a useful transmitting range. It is surprisingly powerful despite its small component count and 3V operating voltage. It will easily transmit over 300....
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For measurement purposes in the electronics laboratory is needed again and again signals of different frequency and waveforms. A common function generator provides sine, for example, triangular and square waves. The frequency must be adjustable and at least....
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This is an article about my new PCB design for CMoy headphone amplifier. Main feature is that the new PCB fits exactly to the classic Altoids tin-can. This new CMoy incorporates moreover bass-boost circuit and constant current charger for 9V battery. P1 is....
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This device is designed to measure the torque in an automobile drive shaft and provide an output to a vehicle data recording system or a portable computer via an RS-232 interface. The received data can then be combined with RPM measurements from the data....
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Build your own Accurate LC Meter (Capacitance Inductance Meter) and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. LC Meter can....
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Here`s how to build your own adjustable power supply based on LM317. The IC LM317 is so versatile that an almost unlimited number of different, small, high grade power supply circuits can be built using it. The configurations can be introduced for different....
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Several years ago, National Semiconductor came up with some very high performance, easy to use audio power amplifier LM3886 circuits. I needed an extra amp so I can bi-amp some of my homemade electrostatic speakers so I tried the LM3886 chip. LM3886....
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Here`s a 2x60W LM4780 Power Amplifier. LM3886 is very interested in our project was the first project, and were acclaimed. But the feedback we receive from you, from scratch, we knew we should make a complete device. One reason for that, but hard to find and....
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Presented here is a Long Range FM Transmitter. This circuit is a super-sensitive, mini-powered FM transmitter consisting of a RF (radio Frequency) oscillator section interfaced with a high sensitivity, wide pass-band audio amplifier and capacitance mike with....
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Presented FM transmitter bug is built using BF414 / BF324 / BF606 transistor. The 30cm antenna has a range of about 30m in the building, more in the open field. Power supply 2x AAA batteries have been used with voltage of 2.75 V. I added resistor 10K in....
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Build your own simple mini FM transmitter. This fun project will show you how to build a mini broadcasting transmitter that can transmit an audio signal up to a quarter mile to any FM receiver. It`s easy to build and a good learning experience. It serves as....
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Here is a very simple telephone broadcaster transmitter which can be used to eavesdrop on a telephone conversation. The circuit can also be used as a wireless telephone amplifier. One important feature of this phone transmitter is that the circuit derives....
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Presented schematic shows how to build simple PIR motion detector sensor. PIR sensors allow you to sense motion, almost always used to detect whether a human has moved in or out of the sensors range. They are small, inexpensive, low-power, easy to use and....
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Here`s a really simple and inexpensive Power LED driver circuit...
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Here is a very simple project of controlling a small DC-motor (taken from an old personal cassette player) with ATmega8. The ATmega8 is having three PWM channels, out of which two are used here. PWM waveforms are fed to MOSFET (RFD3055) H-bridge. Here,....
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This RF inductance meter measures RF chokes in the 500 nH to 50 uH range. I needed a way to measure hand-wound RF inductors in my second lab, and since I would only be doing this occasionally, I didn`t need anything fancy, and since once a friend finishes....
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This easy to build FM transmitter bug can transmit voice to exceptionally good range. Tune trimmer to hear the signal to your near radio. Transmitter frequency range is 88-108 MHz. Max current consumption is 30mA. You can power the fm transmitter bug with a....
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There are many miniature FM transmitter bug circuits online, this one is unique in that it runs completely on solar power. No battery is required. As long as the sun is shining on the PV panel, the transmitter will transmit. The transmitter bug is useful as....
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These have two coils and are controlled by changing the direction of the current flow through the coils in the proper sequence. These motors have only four wires and cannot be connected to this kit. See our Kit 1406 for a Bipolar Stepper driver Kit. 2.....
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I built my first power amplifier when I was still in secondary school. The circuit was made of transistors, didn`t provide much power and had an ugly PCB. Around the same time I got access to a datasheet of TDA1524, a tone/volume control circuit, and I....
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A high quality stereo FM transmitter circuit is shown here. The circuit is based on the IC BA1404 from ROHM Semiconductors. BA1404 is a monolithic FM stereo modulator that has built in stereo modulator, FM modulator and RF amplifier. The FM modulator can be....
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The circuit is based on the IC BA1404 from ROHM Semiconductors. BA1404 is a monolithic FM stereo modulator that has built in stereo modulator, FM modulator, RF amplifier circuitry. BA1404 FM transmitter can be operated from 76 to 108MHz and power supply for....
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This TV transmitter transmits audio and video signal from Camcoder Camera, DVD, VHS, Satellite, video game, etc. Playing them in a channel free from the strip of VHF. These signal can be radiated with a common antenna and captured in an it distances of until....
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This is a TV transmitter for transmitting video of various video sources such as video cameras, Satellite receivers, DVD players, game consoles, etc. TV transmitter`s circuit is working on the 470-580 MHz frequency and can be received on UHF channels 21-34.....
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The USB-Servo is a device to control a servo via USB. A servo is a motorized device that is commonly used in remote controlled cars and planes. I built this device to activate a toy puppet. The puppet has a button on its bottom, if you press the button the....
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This is USB sound card with PCM2902 chip. For the purpose of testing the D / A converters, I built a simple USB sound card with the circuit PCM2902. The card has analog input and output, an electrical S / PDIF output, galvanically separated input and optical....
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This HD TV UHF wideband amplifier(Ultra High Frequency amplifier) has a total gain of 10 to 15 dB in the 400 ? 850 MHz domain frequency so it can be used where the tv signal is weak. For this UHF antenna tv amplifier to work correctly you need to cut the....
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Field strength meter is extremely useful when working with RF devices. It can be used to quickly diagnose whether a transmitter circuit is working, and can be used to detect RF signals in the environment. The simplest field strength meter could be built with....
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This circuit was submitted by Lazar Pancic from Yugoslavia. The sound card for a PC generally has a microphone input, speaker output and sometimes line inputs and outputs. The mic input is designed for dynamic microphones only in impedance range of 200 to....
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Add some resistors in parallel connection for more audio input. To adjust the volume for each input channel, add linear trimmer or potentiometer with configuration: pin1> ground; pin2>output; pin 3>input..
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This is powerful siren circuit diagram. You can get lots of supports from this circuit because you can use this circuit for your alarm circuit then you will be able to get maximum results...
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Enhancements include: analog front end, pin-to-pin compatibility (for existing designs), analog stabilized comparator and simplified external circuit design, improved time and temperature measurement and reduced current. TDC-GP21 is perfectly suited to....
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When speaking of fan control, there are generally 2 ways of doing it, linear control, and pulse-width control. The linear control is the most common. The idea is to decrease the voltage to the fan. If the fan is specified to 12 volts, in most cases you can....
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This is a very small telephone exchange attached only two ordinary Tele phones. Fully bi-directional facility with an intercom system. When a phone is in off hook condition, Exchange will detect it & send ringing pulse to other phone. When it will be picked....
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This multimeter was designed to measure output voltage and current in a PSU, where the current sense shunt resistor is connected in series with load at the negative voltage rail. It needs only one supply voltage that can be acquired from main PSU. An....
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Another feature of this circuit is that you can use the keys "1, 2, 3, 4" of a Philips TV IR remote to turn on or off three relays, The key `4` is used to turn on or off the over temperature alarm. package. LM35 can sense temperature from 0 C to 100 C but it....
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This is a real time clock by using 89c51 micro-controller, clock`s data format is hour:min:sec, and it is displayed on 16x2 LCD, the code has been tested and compilled on Keil uVision compiler, circuit diagram for the project is shown below...
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The positive feedback comparator circuit increases the gain ofthe op-amp, which helps to switch very fast between the two states of a multivibrator. The positive feedback also provides hysteresis to the circuit. A capacitor `C` is connected to the inverting....
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A simple non-commercial grade multiplexer compatbile with telephones. It will supports 4 telephone lines, and will multiplex over one cable. The topic was free of choice, but had to be oriented aroudn the theme of "PrG©vision" (prediction). As you may have....
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The mixer is really handy for DI`ing guitars and basses into soundcards or other mixers and making use of channels on mixes that do not have mike in`s, it comes in handy for one or two guitarists that want to sing and play through one guitar amplifier as....
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A PB-12N23PW-05Q buzzer and I`m trying to use it with ATmega 162. I can`t connect it directly to pin, because from what I`ve read from 162`s datasheet, it can source at most 20 mA. The buzzer takes 50 (or around 25, if we take a look at the graph), so I....
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Creating a 2-bit alu. It has 8 defined functions (the functions are defined by a 3bit code), AND XOR etc, and these functions act on two, 2-bit binary numbers and produce a 2-bit answer. From what I have done so far, I have a decoder that decodes what the....
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Build a logic level shifter (that`s what it`s called) with a few discrete components (transistors and resistors) or you can go for a one-component solution, i. e. an IC. Most ICs won`t accept input voltages as low as 1. 4 V, but I found Fairchild`s FXLP34....
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Planning on basing a QRP transmitter off of this instructables project, seeing as I have a veritable plethora of 555 ics in my shack toolbox. The problem is, this transmitter is designed to operate a bit below the commerical AM band. How is the general....
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Blinks 2 LEDs timely in sequence. Will somebody explain its working I know that capacitor will charge and during the charging the LED will off and whenthey discharge they will on the LED. But why transistor are there..
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Using this(also below in question) circuit to drive a motor, and I heard I should put a decoupling cap in there to smooth out voltage spikes. I have been told to put it close to the ic, and I have also been told not to put it in front of the ic, but between....
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In principle, the square wave oscillator doesn`t have to be a 555 timer, it could be a ring oscillator using inverters as you propose. In practice, using 4000 series CMOS logic for example, the negative output voltage produced would not be able to provide a....
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The piezo element is only connected to Channel 1 (Arduino A[0] port). The channels Ch 1 Ch 6 are connected to female mono jacks and the ground(GND) wiring is in series from jack 1, 2 and 3 so on. till the Ch 6 end to the Arduino GND port. Taped 3 times 787 0....
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My audio source will be a Line Level Audio -2V to +2V AC passed through a 220uF coupling cap and then a low pass filter(RC, 2 pole). The signal will be read by an ADC another one that i have seen is I don`t quite understand this FET-BJT preamp circuit And....
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Q1 and Q2. to form a table, on the left side, list the the four possible states of Q1, Q2; on the right side, write the values that Q1 and Q2 will assume after the next clock pulse. The table will then contain a complete description of the state machine.....
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The 5 V from USB seems to be powering the led on my laptop power brick. Hence even when I switched the power brick off at the wall outlet, the led is still on. When I unplug the USB it goes off but comes back on again as soon as I plug it in. Do Ijust but a....
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As I`m working from a single power supply and I`m trying to keep the design small, I`ve been using the LM386n-1 IC. Also, how would you suggest I control the frequency, which component value should be changed to achieve this - I`ve tried messing with all the....
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Hooked up an electret mic into an opamp and gave output to my arduino microcontroller. The ADC on the microcontroller converts a range of 0 to 5 vV to a 10-bit number (0 to 1023). The problem is that the output from the latter two chips is not "clean". The....
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Powering this circuit with a 6v alkaline battery, the circuit works just fine with 100uf capacitors. But the problem is I want to replace the LED with a dpdt relay, I tried a 6v one I had laying around but it wont budge. Also when I tried the circuit with a....
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An Atmega32A chip and I`ve been trying to program it with a usbasp for quite a few hours. I can change the fuses and write the program, but verification fails. The chip can be erased and fuses can be changed, my only problem is with the verification. The....
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Make those LEDs into LED bar graphs that will show the intensity. For example, I want a song with a loud base to make the bar graph shoot up to the top. The bars of the LED bar graph I would like to just be individual LEDs. I was getting the effect with an....
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Interfacing the BT139-600 TRIAC with this MOC3051-M Opto-triac. Build a snubber circuit for the TRIAC as shown in the MOC3051M opto-triac`s datasheet @ page 8, figure 12. The load will be a 230V AC, 4A motor. What are the recommended characteristics of the....
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The filter R1, R2 and C1 integrate the PWM waveform. But what is the point of the op-amp It looks like a non-inverting amplifier to me, with the gain set by R6 and R7 - if I`m not mistaken. But why does the integrated DC voltage need amplification Perhaps, I....
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The piezo effect works both ways: if you apply a voltage the piezo stretches, but also if it stretches it creates a voltage. This principle is used to create a feedback signal which drives the oscillator. The advantage of the self drive is that it will....
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Using the 555 timer as an oscillator in the high voltage power supply section. Can the design be changed to use an output from the micro-controller to generate an oscillating signal instead of the 555. The first question is that would such a design work If....
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Switch 50V AC voltage. Maximum drained current will be 5A. Frequency is 50Hz. Switching speed is not important, can be real slow, it is not a problem in my application. I wanted to use solid state relay at first for this purpose. But as soon as I started to....
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220V bulb where one end of the relay is connected to the 220V dc and the other end to ground; and is switched one to the other using the output of a PWM as shown in the block diagram below: However, I am afraid that this is a poor design and not safe: no....
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The power supply varies, and the circuit must operate on under 10uA of current (not counting charging the cap). It triggers an SCR every 10-30 seconds as long as the power supply is above 1. 8VDC, and must operate across a range of 1. 8 and 7. 0 VDC. The....
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Why are four legs connected to the green LED and two to the amber LED in the 4017 traffic light circuit Shouldn`t it be able to do with only one leg per LED Each output is consecutively active for the same time. By wired-OR-ing outputs you can create longer....
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A suitable method to sense when some LEDs in my Garage Door Opener are on. A power source (perhaps the same as Vout below) runs to a 1. 5Kohm resistor which runs to 6 LEDs then a transistor of some sort. The transistor is attached to ground and pin 7 on a....
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The ULN2003A and Zener from the driver board inside the same device. It`s a 5 wires motor, but the one in the schematic is 6 wires. I suppose the only difference is that the 5 wire version has the two center taps joined together so that`s what you see in my....
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Can I assume that most of the 555 chips from different manufacturers are interchangable (same pin configuration), however the programs/diagrams have pins that way just to look simpler I can always route my own weird ways on the actual chip to match the....
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Because you are powering the MCU via USB, this common zero voltage should be the same as the supply and therefore connected to the 0V (UVSS) line...
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No problems turning it on, but after I unload the input (no input current), the triac doesn`t turn off. The load is standard RS-232 voltages (+/- 12V), speed 56k. You mentioned you have already tried using an OptoTriac, so the schematic of how you connected....
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To create a square-wave generator but I would like to modify it by getting an output that runs from 0 to +5V, as well as changing the signal so that I can change the duty cycle of the pulse(PWM)...
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30 incandescent lightbulbs be controlled by my arduino uno on 3 channels (10 bulbs to a channel in parallel). I`ve used the arduino before to control a number of red, green and blue LEDs - I used a simple schematic using three transistors. I`m just not sure....
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Build a small battery powered device containing a servo. I would like to be able to turn off the servo to save battery life. I have read previously that MOSFETs can be used to do this, but I am having trouble finding example circuits that are detailed enough....
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Build a Wien bridge oscillator that oscillates at 2. 1kHz and that can be switched on by a transistor. The reason for me placing a transistor switch in the circuit is so that I can turn the oscillator on and off from a PIC MCU. However, when I build the....
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To do this, I want to push a button to initiate the timer, which will then light 3 x leds. After each 5 minute segment is up, one of the LEDs should go out. Finally, when 15 mins is up, I want to ring a bell (just once) using a solenoid. Trouble is - I don`t....
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Although my circuit allows for different combinations of input voltages (Vin) and output voltages (Vout). The case I am debugging is with Vin=3. 6V and Vout=7. 2V. The Load was a 120 ohm resistor. I calculated the duty cycle D=0. 5 (i. e. 50%). This seems to....
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Build an oscillator that will satisfy a few requirements. The main requirement is to have exactly one capacitor. Another one is to have high Q and sine wave output. I am considering Hartley`s oscillator design. Since it has only one cap. I don`t what to....
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Build the LC oscillator show on the bottom of this page for some school project and I`m having a bit of problems translating the theoretical circuit into a real-world one. I think I get how the circuit works on paper. We have a LC resonant circuit which will....
Four button RF remote is used to turn ON / OFF four different devices independently. Any of the four outputs can be configured to work independently in either toggle or momentary mode. Outputs are buffered by BC549 NPN transistors and can drive low voltage....
This is simple 3-digits digital volt meter.PIC16F676 used to read analog signal(voltage) and display the value on 3-digits 7-segment. You can apply similar principles to measure DC current with parallel R shunt..
As shown in the schematic, temperature sensor of our electronic thermometer is LM35DZ. There are some kinds of LM35 IC, since it is cheap and easy to find we used LM35DZ in our project. It measures from 0?C to 100?C with a very linear output graph.For one....
The amplifier has exactly the same architecture as TX500 with the difference that TX300 has only one stage variable VHF amplifier. It is a cute schematic that was made for all of you who wanted something even simpler than TX500 and with not as many necessary....
The TX500 is a simple to build 500mW FM Transmitter. It consists of three blocks; modulator / oscillator, two stage 500mW VHF amplifier and LED based power meter. The TX500 allows to transmit audio signals to FM band at frequencies from 88 MHz to 108 MHz.....
This tiny receiver is not much bigger than an AA cell. It is powered off two LR44 button cells, which are expensive and I assume wouldn`t last terribly long. I`ll be on the lookout for LR44`s at the markets and $2 shops now that I`ve got this radio! As with....
This project is a FM Radio based on TDA7000 and LM386 integrated circuits. What is unusual about TDA7000 IC is how it operates. It is a proper FM superhet receiver, with the usual local oscillator, mixer, IF amplifier, limiter, and phase detector. The....
Here is the circuit diagram of the simple FM transmitter using a transistor. Great performance or range is not guaranteed here, because this is an elementary design. General purpose radio frequency transistor BF 494 (Q1) is used here for obtaining FM....
This FM transmitter is about the simplest and most basic FM transmitter it is possible to build and have a useful transmitting range. It is surprisingly powerful despite its small component count and 3V operating voltage. It will easily transmit over 300....
For measurement purposes in the electronics laboratory is needed again and again signals of different frequency and waveforms. A common function generator provides sine, for example, triangular and square waves. The frequency must be adjustable and at least....
This is an article about my new PCB design for CMoy headphone amplifier. Main feature is that the new PCB fits exactly to the classic Altoids tin-can. This new CMoy incorporates moreover bass-boost circuit and constant current charger for 9V battery. P1 is....
This device is designed to measure the torque in an automobile drive shaft and provide an output to a vehicle data recording system or a portable computer via an RS-232 interface. The received data can then be combined with RPM measurements from the data....
Build your own Accurate LC Meter (Capacitance Inductance Meter) and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. LC Meter can....
Here`s how to build your own adjustable power supply based on LM317. The IC LM317 is so versatile that an almost unlimited number of different, small, high grade power supply circuits can be built using it. The configurations can be introduced for different....
Several years ago, National Semiconductor came up with some very high performance, easy to use audio power amplifier LM3886 circuits. I needed an extra amp so I can bi-amp some of my homemade electrostatic speakers so I tried the LM3886 chip. LM3886....
Here`s a 2x60W LM4780 Power Amplifier. LM3886 is very interested in our project was the first project, and were acclaimed. But the feedback we receive from you, from scratch, we knew we should make a complete device. One reason for that, but hard to find and....
Presented here is a Long Range FM Transmitter. This circuit is a super-sensitive, mini-powered FM transmitter consisting of a RF (radio Frequency) oscillator section interfaced with a high sensitivity, wide pass-band audio amplifier and capacitance mike with....
Presented FM transmitter bug is built using BF414 / BF324 / BF606 transistor. The 30cm antenna has a range of about 30m in the building, more in the open field. Power supply 2x AAA batteries have been used with voltage of 2.75 V. I added resistor 10K in....
Build your own simple mini FM transmitter. This fun project will show you how to build a mini broadcasting transmitter that can transmit an audio signal up to a quarter mile to any FM receiver. It`s easy to build and a good learning experience. It serves as....
Here is a very simple telephone broadcaster transmitter which can be used to eavesdrop on a telephone conversation. The circuit can also be used as a wireless telephone amplifier. One important feature of this phone transmitter is that the circuit derives....
Presented schematic shows how to build simple PIR motion detector sensor. PIR sensors allow you to sense motion, almost always used to detect whether a human has moved in or out of the sensors range. They are small, inexpensive, low-power, easy to use and....
Here is a very simple project of controlling a small DC-motor (taken from an old personal cassette player) with ATmega8. The ATmega8 is having three PWM channels, out of which two are used here. PWM waveforms are fed to MOSFET (RFD3055) H-bridge. Here,....
This RF inductance meter measures RF chokes in the 500 nH to 50 uH range. I needed a way to measure hand-wound RF inductors in my second lab, and since I would only be doing this occasionally, I didn`t need anything fancy, and since once a friend finishes....
This easy to build FM transmitter bug can transmit voice to exceptionally good range. Tune trimmer to hear the signal to your near radio. Transmitter frequency range is 88-108 MHz. Max current consumption is 30mA. You can power the fm transmitter bug with a....
There are many miniature FM transmitter bug circuits online, this one is unique in that it runs completely on solar power. No battery is required. As long as the sun is shining on the PV panel, the transmitter will transmit. The transmitter bug is useful as....
These have two coils and are controlled by changing the direction of the current flow through the coils in the proper sequence. These motors have only four wires and cannot be connected to this kit. See our Kit 1406 for a Bipolar Stepper driver Kit. 2.....
I built my first power amplifier when I was still in secondary school. The circuit was made of transistors, didn`t provide much power and had an ugly PCB. Around the same time I got access to a datasheet of TDA1524, a tone/volume control circuit, and I....
A high quality stereo FM transmitter circuit is shown here. The circuit is based on the IC BA1404 from ROHM Semiconductors. BA1404 is a monolithic FM stereo modulator that has built in stereo modulator, FM modulator and RF amplifier. The FM modulator can be....
The circuit is based on the IC BA1404 from ROHM Semiconductors. BA1404 is a monolithic FM stereo modulator that has built in stereo modulator, FM modulator, RF amplifier circuitry. BA1404 FM transmitter can be operated from 76 to 108MHz and power supply for....
This TV transmitter transmits audio and video signal from Camcoder Camera, DVD, VHS, Satellite, video game, etc. Playing them in a channel free from the strip of VHF. These signal can be radiated with a common antenna and captured in an it distances of until....
This is a TV transmitter for transmitting video of various video sources such as video cameras, Satellite receivers, DVD players, game consoles, etc. TV transmitter`s circuit is working on the 470-580 MHz frequency and can be received on UHF channels 21-34.....
The USB-Servo is a device to control a servo via USB. A servo is a motorized device that is commonly used in remote controlled cars and planes. I built this device to activate a toy puppet. The puppet has a button on its bottom, if you press the button the....
This is USB sound card with PCM2902 chip. For the purpose of testing the D / A converters, I built a simple USB sound card with the circuit PCM2902. The card has analog input and output, an electrical S / PDIF output, galvanically separated input and optical....
This HD TV UHF wideband amplifier(Ultra High Frequency amplifier) has a total gain of 10 to 15 dB in the 400 ? 850 MHz domain frequency so it can be used where the tv signal is weak. For this UHF antenna tv amplifier to work correctly you need to cut the....
Field strength meter is extremely useful when working with RF devices. It can be used to quickly diagnose whether a transmitter circuit is working, and can be used to detect RF signals in the environment. The simplest field strength meter could be built with....
This circuit was submitted by Lazar Pancic from Yugoslavia. The sound card for a PC generally has a microphone input, speaker output and sometimes line inputs and outputs. The mic input is designed for dynamic microphones only in impedance range of 200 to....
Add some resistors in parallel connection for more audio input. To adjust the volume for each input channel, add linear trimmer or potentiometer with configuration: pin1> ground; pin2>output; pin 3>input..
This is powerful siren circuit diagram. You can get lots of supports from this circuit because you can use this circuit for your alarm circuit then you will be able to get maximum results...
Enhancements include: analog front end, pin-to-pin compatibility (for existing designs), analog stabilized comparator and simplified external circuit design, improved time and temperature measurement and reduced current. TDC-GP21 is perfectly suited to....
When speaking of fan control, there are generally 2 ways of doing it, linear control, and pulse-width control. The linear control is the most common. The idea is to decrease the voltage to the fan. If the fan is specified to 12 volts, in most cases you can....
This is a very small telephone exchange attached only two ordinary Tele phones. Fully bi-directional facility with an intercom system. When a phone is in off hook condition, Exchange will detect it & send ringing pulse to other phone. When it will be picked....
This multimeter was designed to measure output voltage and current in a PSU, where the current sense shunt resistor is connected in series with load at the negative voltage rail. It needs only one supply voltage that can be acquired from main PSU. An....
Another feature of this circuit is that you can use the keys "1, 2, 3, 4" of a Philips TV IR remote to turn on or off three relays, The key `4` is used to turn on or off the over temperature alarm. package. LM35 can sense temperature from 0 C to 100 C but it....
This is a real time clock by using 89c51 micro-controller, clock`s data format is hour:min:sec, and it is displayed on 16x2 LCD, the code has been tested and compilled on Keil uVision compiler, circuit diagram for the project is shown below...
The positive feedback comparator circuit increases the gain ofthe op-amp, which helps to switch very fast between the two states of a multivibrator. The positive feedback also provides hysteresis to the circuit. A capacitor `C` is connected to the inverting....
A simple non-commercial grade multiplexer compatbile with telephones. It will supports 4 telephone lines, and will multiplex over one cable. The topic was free of choice, but had to be oriented aroudn the theme of "PrG©vision" (prediction). As you may have....
The mixer is really handy for DI`ing guitars and basses into soundcards or other mixers and making use of channels on mixes that do not have mike in`s, it comes in handy for one or two guitarists that want to sing and play through one guitar amplifier as....
A PB-12N23PW-05Q buzzer and I`m trying to use it with ATmega 162. I can`t connect it directly to pin, because from what I`ve read from 162`s datasheet, it can source at most 20 mA. The buzzer takes 50 (or around 25, if we take a look at the graph), so I....
Creating a 2-bit alu. It has 8 defined functions (the functions are defined by a 3bit code), AND XOR etc, and these functions act on two, 2-bit binary numbers and produce a 2-bit answer. From what I have done so far, I have a decoder that decodes what the....
Build a logic level shifter (that`s what it`s called) with a few discrete components (transistors and resistors) or you can go for a one-component solution, i. e. an IC. Most ICs won`t accept input voltages as low as 1. 4 V, but I found Fairchild`s FXLP34....
Planning on basing a QRP transmitter off of this instructables project, seeing as I have a veritable plethora of 555 ics in my shack toolbox. The problem is, this transmitter is designed to operate a bit below the commerical AM band. How is the general....
Blinks 2 LEDs timely in sequence. Will somebody explain its working I know that capacitor will charge and during the charging the LED will off and whenthey discharge they will on the LED. But why transistor are there..
Using this(also below in question) circuit to drive a motor, and I heard I should put a decoupling cap in there to smooth out voltage spikes. I have been told to put it close to the ic, and I have also been told not to put it in front of the ic, but between....
In principle, the square wave oscillator doesn`t have to be a 555 timer, it could be a ring oscillator using inverters as you propose. In practice, using 4000 series CMOS logic for example, the negative output voltage produced would not be able to provide a....
The piezo element is only connected to Channel 1 (Arduino A[0] port). The channels Ch 1 Ch 6 are connected to female mono jacks and the ground(GND) wiring is in series from jack 1, 2 and 3 so on. till the Ch 6 end to the Arduino GND port. Taped 3 times 787 0....
My audio source will be a Line Level Audio -2V to +2V AC passed through a 220uF coupling cap and then a low pass filter(RC, 2 pole). The signal will be read by an ADC another one that i have seen is I don`t quite understand this FET-BJT preamp circuit And....
Q1 and Q2. to form a table, on the left side, list the the four possible states of Q1, Q2; on the right side, write the values that Q1 and Q2 will assume after the next clock pulse. The table will then contain a complete description of the state machine.....
The 5 V from USB seems to be powering the led on my laptop power brick. Hence even when I switched the power brick off at the wall outlet, the led is still on. When I unplug the USB it goes off but comes back on again as soon as I plug it in. Do Ijust but a....
As I`m working from a single power supply and I`m trying to keep the design small, I`ve been using the LM386n-1 IC. Also, how would you suggest I control the frequency, which component value should be changed to achieve this - I`ve tried messing with all the....
Hooked up an electret mic into an opamp and gave output to my arduino microcontroller. The ADC on the microcontroller converts a range of 0 to 5 vV to a 10-bit number (0 to 1023). The problem is that the output from the latter two chips is not "clean". The....
Powering this circuit with a 6v alkaline battery, the circuit works just fine with 100uf capacitors. But the problem is I want to replace the LED with a dpdt relay, I tried a 6v one I had laying around but it wont budge. Also when I tried the circuit with a....
An Atmega32A chip and I`ve been trying to program it with a usbasp for quite a few hours. I can change the fuses and write the program, but verification fails. The chip can be erased and fuses can be changed, my only problem is with the verification. The....
Make those LEDs into LED bar graphs that will show the intensity. For example, I want a song with a loud base to make the bar graph shoot up to the top. The bars of the LED bar graph I would like to just be individual LEDs. I was getting the effect with an....
Interfacing the BT139-600 TRIAC with this MOC3051-M Opto-triac. Build a snubber circuit for the TRIAC as shown in the MOC3051M opto-triac`s datasheet @ page 8, figure 12. The load will be a 230V AC, 4A motor. What are the recommended characteristics of the....
The filter R1, R2 and C1 integrate the PWM waveform. But what is the point of the op-amp It looks like a non-inverting amplifier to me, with the gain set by R6 and R7 - if I`m not mistaken. But why does the integrated DC voltage need amplification Perhaps, I....
The piezo effect works both ways: if you apply a voltage the piezo stretches, but also if it stretches it creates a voltage. This principle is used to create a feedback signal which drives the oscillator. The advantage of the self drive is that it will....
Using the 555 timer as an oscillator in the high voltage power supply section. Can the design be changed to use an output from the micro-controller to generate an oscillating signal instead of the 555. The first question is that would such a design work If....
Switch 50V AC voltage. Maximum drained current will be 5A. Frequency is 50Hz. Switching speed is not important, can be real slow, it is not a problem in my application. I wanted to use solid state relay at first for this purpose. But as soon as I started to....
220V bulb where one end of the relay is connected to the 220V dc and the other end to ground; and is switched one to the other using the output of a PWM as shown in the block diagram below: However, I am afraid that this is a poor design and not safe: no....
The power supply varies, and the circuit must operate on under 10uA of current (not counting charging the cap). It triggers an SCR every 10-30 seconds as long as the power supply is above 1. 8VDC, and must operate across a range of 1. 8 and 7. 0 VDC. The....
Why are four legs connected to the green LED and two to the amber LED in the 4017 traffic light circuit Shouldn`t it be able to do with only one leg per LED Each output is consecutively active for the same time. By wired-OR-ing outputs you can create longer....
A suitable method to sense when some LEDs in my Garage Door Opener are on. A power source (perhaps the same as Vout below) runs to a 1. 5Kohm resistor which runs to 6 LEDs then a transistor of some sort. The transistor is attached to ground and pin 7 on a....
The ULN2003A and Zener from the driver board inside the same device. It`s a 5 wires motor, but the one in the schematic is 6 wires. I suppose the only difference is that the 5 wire version has the two center taps joined together so that`s what you see in my....
Can I assume that most of the 555 chips from different manufacturers are interchangable (same pin configuration), however the programs/diagrams have pins that way just to look simpler I can always route my own weird ways on the actual chip to match the....
Because you are powering the MCU via USB, this common zero voltage should be the same as the supply and therefore connected to the 0V (UVSS) line...
No problems turning it on, but after I unload the input (no input current), the triac doesn`t turn off. The load is standard RS-232 voltages (+/- 12V), speed 56k. You mentioned you have already tried using an OptoTriac, so the schematic of how you connected....
To create a square-wave generator but I would like to modify it by getting an output that runs from 0 to +5V, as well as changing the signal so that I can change the duty cycle of the pulse(PWM)...
30 incandescent lightbulbs be controlled by my arduino uno on 3 channels (10 bulbs to a channel in parallel). I`ve used the arduino before to control a number of red, green and blue LEDs - I used a simple schematic using three transistors. I`m just not sure....
Build a small battery powered device containing a servo. I would like to be able to turn off the servo to save battery life. I have read previously that MOSFETs can be used to do this, but I am having trouble finding example circuits that are detailed enough....
Build a Wien bridge oscillator that oscillates at 2. 1kHz and that can be switched on by a transistor. The reason for me placing a transistor switch in the circuit is so that I can turn the oscillator on and off from a PIC MCU. However, when I build the....
To do this, I want to push a button to initiate the timer, which will then light 3 x leds. After each 5 minute segment is up, one of the LEDs should go out. Finally, when 15 mins is up, I want to ring a bell (just once) using a solenoid. Trouble is - I don`t....
Although my circuit allows for different combinations of input voltages (Vin) and output voltages (Vout). The case I am debugging is with Vin=3. 6V and Vout=7. 2V. The Load was a 120 ohm resistor. I calculated the duty cycle D=0. 5 (i. e. 50%). This seems to....
Build an oscillator that will satisfy a few requirements. The main requirement is to have exactly one capacitor. Another one is to have high Q and sine wave output. I am considering Hartley`s oscillator design. Since it has only one cap. I don`t what to....
Build the LC oscillator show on the bottom of this page for some school project and I`m having a bit of problems translating the theoretical circuit into a real-world one. I think I get how the circuit works on paper. We have a LC resonant circuit which will....
