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Voltage Controlled Power Supply Tester by OPA277
Description: While testing the power supplies or discovering their potential problems, you must apply dynamic and static tests. This circuit, namely current sink, makes this job easier for you. It can draw 0 to 1.5A current from the load depending on the input voltage between 0 to 5V applied to …
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Frequency Counter by PIC16F628
In this project we are building a basic and low cost frequency counter circuit . It can measure from 16Hz to 100Hz signals with a maximum amplitude of 15V. The sensitivity is high, the resolution is 0.01 Hz. The input signal can be a sine, a square or a triangle waveform. The counter can be used …
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20 Watt Stereo Audio Power Amplifier by LM1875
Description: Here is a reliably high sound quality audio power amplifier project based on the National Semiconductor’s LM1875 IC. The circuit that we give is a similar form of the application circuit in the datasheet that NS provides. It is really easy to build and low cost. The voltage gai …
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USB 5V to 12V DC-DC Step-Up Converter by LT1618
Description: This is a 5V to 12V DC-DC step-up (boost) converter circuitry that is especially ideal for the USB powered applications. First of all a USB port has two current supply modes. Before detecting the connected device, it supplies maximum 100mA to the load. After recognizing the device, i …
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30W MOSFET Audio Amplifier IRF530-IRF9530
Description: This project was a sort of challenge: designing an audio amplifier capable of delivering a decent output power with a minimum parts count, without sacrificing quality. The Power Amplifier section employs only three transistors and a handful of resistors and capacitors in a shun …
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Programmable Current Source by LM317
Description: Accurate and stable current supplies are generally needed in electronic labs especially for creating V-I curves, charging and discharging batteries, preloading power supplies and for many other purposes and applications. This circuit provides a current supply that can be progr …
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Basic Concepts of Designing an RF PCB Board
In this article, we point out some important facts in designing RF application PCB boards. Of course there are many other facts that are not listed below but for the beginners these may be enough for now. First of all, separate the analog , RF and digital parts of your system and try to desi …
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Drive Multiple LEDs by Using Only One NiMH Cell
Description: This simple circuit allows us to drive serially connected seven LEDs by using a single NiMH (Nickel Metal Hydride) AA cell. As you can see there are a few components, a CMOS 555 timer, an NPN transistor, an inductor, three resistors and two capacitors. The circuit produces …
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LM317 Based 0 to 3V Adjustable Power Supply
Description: This is an LM317 based adjustable voltage regulator with a maximum output of 3V and 1.5A. The output voltage depends on the VIN, R1 and R2 values, so the circuit can be modified to use with a maximum output of greater than 3V. The maximum current output is also independent of th …
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PIC Controlled Relay Driver
This circuit is a relay driver that is based on a PIC16F84A microcontroller. The board includes four relays so this lets us to control four distinct electrical device. The controlled device may be a heater, a lamp, a computer or a motor. To use this board in the industrial area, the supply part is d …
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Frequency Counter
In this project we are building a basic and low cost frequency counter circuit . It can measure from 16Hz to 100Hz signals with a maximum amplitude of 15V. The sensitivity is high, the resolution is 0.01 Hz. The input signal can be a sine, a square or a triangle waveform. The counter can be used …
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Cell Phone Detector
This is a mobile phone sniffer circuit that can detect the signals being used in the GSM (Global System for Mobile Communication) band at about 900 MHz. Since the signals are digitally encoded, it can detect only the signal activity, not the speech or the message contents. A headphone is used to hea …
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RS232 - RS485 Converter with Automatic RX - TX Control
Today, although the wireless technology grows very fast, the long distance funicular communication still keeps its popularity. The reason is obvious that cost and complexity is high at the wireless communication. RS232 is probably one of the most used, easy to develop and easy to apply communicat …
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PIC and EEPROM Programmer
In this project we are building a JDM programmer that can handle PIC12, PIC16 and PIC18 family microcontrollers and some popular 24C family EEPROMs. The programmer also provides ICSP feature that allows In-Circuit Serial Programming. So if you desire, you will not have to carry your MCU each time …
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High Output Oscillator
Description: This is a high output oscillator set at 1Ghz. Designed out of frustration of not having a matched PNP transistor. The circuit will deliver 3v RF with the components shown. If you were to use two 100mW rated transistors, you would obtain around 300mW out. Tuned circuit is L1,L …
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500 mW VHF Video Transmitter
Description: Q1 (BC548C) is a modulated oscillator operating in the Commercial VHF Television Band and Q2 (BC548C or 2N4427) is an VHF RF Amplifier. Tuned circuits consist of C4, L1, C8, L3, and the two 15 pF trimmer capacitors across the collectors and emitters of both transistors. Other N …
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Switch Debouncer with Only One Inverter
Description: This circuit acts as a debouncer that prevents multiple logic signal transmitting when a switch is pressed. It takes its logic power from only the remote pull-up resistor R2 and can be used in non-energized devices such as a device in a system that's just coming from the stand-b …
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Simple No-Tune Wi-Fi Sniffer
Description: Here is a circuit of a very basic No-Tune Wi-Fi Sniffer. It’s about as simple as it gets, using only two transistors. It could detect my notebook at 10 feet with a tiny vertical. No doubt, a Well Tuned Dipole would increase it’s range. Q1+Q2 are RF amplifier stages tun …
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TTL Level - RS232 Level Converter by MAX232
Description: This is a small portable RS232 - TTL converter circuit that is based on one of the most common ICs MAX232. The minimum number of components are used to operate MAX232. Additionally a +5V voltage regulator 7805 and two supply capacitors are used. If you want to bypass the regulator …
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Simple Cell Phone Jammer
Description: A “Cell Jammer” is just way of saying “Dirty Transmitter” which happens to transmit within the Cellular Phone Bands. Reality is, the dirtier the better. The 555 timer [8 pin] IC simply makes a noise. It’s coupled via C4 [electrolytic] to modulate t …
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