New Circuits Page 215
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The Hand Steadiness Tester is a game which tests the steadiness of your hand. The player has to take the ring from one end to another end without touching it to the wire. In this the player gets 4 turns. If the player touches the wire 4 times he has to reset....
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An ultra-low-noise, low-distortion op ampthe AD797is combined with the ADS 11 op amp, which offers a high bandwidth and a 100-mA output drive capability. The composite-amplifier circuit serves quite well when driving high resolution ADC`s and ATE systems.....
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The watchdog timer contains a counter, IC3, in addition to the usual retriggerable 555 timer, ICl. The counter will so..
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This IC chip was designed specifically for use in power boosting applications in automobiles. It is self protecting against short circuits and thermal problems. In the bridge configuration shown it will deliver 20 watts of power into a 2 ohm speaker....
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This is a classic signal mixer that is used for audio purpose. VR1 & VR2 are inputs audio volume controlers and VR3 is used to control the balance between Input1 and Input2. connect a dynamic microphone to Input1 and a music without vocal to Input2, then....
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The application that to you we propose is a simple filter of region that limits the acoustic region (20-20000Hz) in the region 20-100Hz.
With the manufacture that to you we propose you can make a active filter in order to you lead a loudspeaker of very....
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This is a selection of small self-contained alarm circuits. They have a very low standby current; and are suitable for battery operation...
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The 15v zener is fed via the 4K7 resistor from the input. With 0.6v across the base - emitter of the PNP transistor, this establishes a voltage of 14.4 across the 3K3, so there must be a current of nearly 4.4mA through the 3K3. This current is available to....
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This circuit is a high performance charger for gelled electrolyte lead-acid batteries. Charger quickly recharges battery and shuts off at full charge. Initially, charging current is limited to 2A. As the battery voltage rises, current to the battery....
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A few months ago as I was surfing on the net, I saw an oscilloscope based on PIC18F2550 microcontroller and a KS0108 controller based graphical LCD. That was Steven Cholewiak's web site. I had never seen before so amazing microcontroller-only oscilloscope.....
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The circuit uses independent timers to flash two light emitting diodes. Any time that light emitting diode D1 is lit__light emitting diode D2 will be switched off. Light emitting diode D3 is on if both D1 and D2 are off.
Two versions of the circuit are....
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Video designs are often pressed to operate on the lowest possible rail voltagesa simple result of the trend towards lower voltage logic and the advantages of sharing supply potentials wherever possible...
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Most of the transistors in this speaker protector function as switches. Normally, Q4, Q5, and K1 are on and the speakers are connected to the amplifier. However, if a large dc voltage appears at an amplifier output, either Q3, or Ql and Q2 turn on, biasing....
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This transmitter can be tuned to the FM broadcast band, 2 meters,-or other VHF bands by changing C5 and Ll. The values given for C5 and Ll will place the frequency somewhere in the FM broadcast band. Ll is 4 turns of #20 enameled wire airwound, % inch in....
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TimeGen is an engineering CAD tool which allows an engineer the capability to quickly and effectively draw timing diagrams. The waveforms can easily be exported to other Window programs, such as Microsoft Word, for use in writing design specifications.....
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SwitcherCAD¾ III is a high performance Spice III simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators. Our enhancements to Spice have made simulating switching regulators extremely....
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To decouple the sensors from the meter amplifier, either a reference junction at ooc or a bucking voltage set at room temperature may be used. The latter method is simpler, but is sensitive to changes in ambient temperature. ..
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This is a circuit for a game of the shooting gallery variety. IC2a and b form an astable multivibrator clocking ICl which causes LEDs 1-8 to flash in turn LED 5 is the target LED and the object of the game is to depress PBI just as LED 5 comes on. If this is....
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Using an RC oscillator, an up to 24-stage ripple counter O) 16777216 or 2U, and a 0.1-Hz count-rate with #..
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Rosemary's original test circuit is shown in the article she tried to have published in a "refereed" scientific journal, but the submission was always rejected. In the last 5 months, I have had extensive email correspondence, and numerous telephone....
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The circuit in Figure 1 is an RS-232/485 converter that uses the transmitted signal itself to control the flow. The circuit uses MAX232 and MAX483 interface circuits, IC1 and IC2 from Maxim Integrated Products (http://www.maxim-ic.com) to convert between the....
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A Class A // Class AB amplifier rated 100 Watts when driving a 4 ohm loudspeaker. This circuit developed out of my 30+ years of JLH class-A based investigations.
The original `simple` 1969 JLH class-A design provided excellent first cycle accuracy through....
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The amplifier"s gain is nominally 20 dB. Its frequency response is determined primarily by the value of just a few components-primarily C1 and Rl. The values in the schematic diagram provide a response of ±3.0 dB from about 120 to over 20,000 Hz.....
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The input impedance is the value of potentiometer Rl. If your instrument has extra-deep bass, change capacitor Cl to 0.5 mF. What appears to be an extra part in the feedback loop is a brightening tone control. The basic feedback from the op amp's output (pin....
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Except for the coupling and decoupling capacitors, IC1 is a complete wideband amplifier that has a fixed gain of 20 dB to 450 MHz. No external compensation is required. since the NE5205 functions as a gain block, two or more cart be easily cascaded to....
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The buck-boost configurationnf the MAX634 is well suited for dual output de-de converters. Only a second winding on the inductor is needed. Typically, this second winding is bifilar-primary and secondary are wound simultaneously using two wires in....
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Process-control applications often require a monostable multivibrator (one-shot) with a pulse width that c..
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The circuit receives its power from a 15-V wall adapter (not shown). The circuit takes advantage of the fact that th..
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A minimum number of parts yields a compact switching converter that can provide sufficient voltage to drive white LEDs. The resulting lamp is much more efficient, in terms of lumen hours per pound of battery, than incandescent bulbs, and because the color of....
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Light emitting diodes are advan- tageous due to their smaller size, low current consumption and catchy colours they emit. Here is a running message display circuit wherein the letters formed by LED arrangement light up progressively. Once all the letters of....
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C ircuit of a new type of remote control switch is described here. This circuit functions with inaudible (ultrasonic) sound. Sound of frequency up to 20 kHz is audible to human beings. The sound of frequency above 20 kHz is called ultrasonic sound. The....
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In the circuit in Fig. 1, ICla produces the integral term required but also has the side effect of producing a proportional term not required, so this term is subtracted by IClb leaving a pure integral. If the ratio R2/R5 does not exactly match the ratio of....
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This circuit is not open for discussion. Although working perfectly, it was experimental. I will answer no emails in regards to this circuit.
If you are looking for a more serious and reliable bug detector, go to the Countersurveillance Monitor article on....
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A simple solenoid driver uses incandescent lamp filaments as on-indicators to limit power consumption. High magnetic reluctance (opposition to flux) in the coil of an armature-driven device, such as a solenoid or relay, calls for a surge of activation....
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A time delay relay is a relay that stays on for a certain amount of time once activated. This time delay relay is made up of a simple adjustable timer circuit which controls the actual relay. The time is adjustable from 0 to about 20 seconds with the parts....
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This neat little circuit can play 8 note tunes at any speed you want. You select the notes with 8 trim pots. The speed in selected through a ninth pot. The circuit draws very little power and can be powered by a 9 volt battery, with the addition of a 7805....
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A variable dock-pulse generator is made up of two sections of IC1 (a 4069 CMOS hex inverter). Rl, Sl, and capacitors Cl through C6. By adjusting Rl and switching one of the capacitors into the circuit, the clock"s pulse rate can be varied over a wide....
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The 12 Volt power in my application comes from a small solar power system, it may also be provided by a suitable wall-wart DC power supply. The cistern is located below the toilet tank, the pump moves the water up to the toilet`s tank. The pump is switched....
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A very regular configuration of the 555 astable timer to work as a timer to trigger an alarm or any other equipment connected to pin 3. R resistor should be replaced with a potentiometer that will change the time delay. Capacitor C should be calculated too....
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This project is built on the third section of the PC board, identified by "SIREN" and "Project 5." You will notice the similarity between this circuit and the LED FLASHER circuit from project 2. The only differences are the LED has been removed and the 22R....
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Six preset controls and seven selector switches enable a vast range of different sounds to be produced and altered at will. Such sounds as steam trains chuffing, helicopters flying, bird chirping, and machine guns firing are possible, as well as the usual....
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This type of design can produce a very high amperage current for a faction a second that can used to do some useful work if properly harnessed. The switching device could be a rotating spark gap as used by Nikola Tesla or some high speed electronic device,....
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The single-chip, burglar -alarm circuit shown uses a dual 556 timer, draws 10 mA of standby current, and generates a pulsing alarm signal that conserves battery energy. Once activated, the alarm wilLremain on, independent of the subsequent state of any of....
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This Cheap circuit will amaze you with its wide range recieving signal between 6 and 17Mhz (49-19meters). Power supply is not necesery, just connect it to your pc, place the antena to your home piping network and voila!..
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Although the concept of a totally accessible system represents an ideal situation for users, designers now must limit access toand conceal code sequences forsoftware routines for calibration, diagnostics, memory erasure, system reset, and more. In a system....
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This box is a portable transfer standard to maintain and carry with you a local time signal of 59 short beeps (pips) plus a long 0.4 sec beeeeep on the full minute. At the start of the job, the box is started by manually synchronising it by ear with a....
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This is a circuit to use a standard, low quality opto isolator to transfer an analogue signal with reasonable linearity and without complicated feedback loops to monitor and linearise it. The circuit was designed to interface a mains driven thryristor motor....
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This circuit has high output only when all three inputs are high. The noninverting-input current, when all thre..
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TheCA3189E is a comprehensive FM-IF system designed for high fidelity FM tuners. It includes a three stage FM-IF amplifier/limiter configuration with level detectors for each stage, a double-balanced quadrature FM detector and an audio amplifier that....
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The GPS is based on 24 satellites located in six orbital planes at a height of 20 200 km and circle the Earth every 12 h. Each plane is inclined at 55 to the Earth’s equator and contains four satellites. The GPS positioning is based on oneway time-of-arrival....
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This stero amp will give you 4-8W/ch of zero feedback triode power for less than a pair of Chinese 300B's ...if you know where to shop. For those of you who are unfamiliar with this lil' tube here's the poop: The 5687 is a 9-pin miniature twin triode (a la....
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The interest for circuits of tubes, remains big. Thus I will give completed in enough big degree, circuit of preamplifier. It is mainly constituted by the department of main preamplifier, the department of input selector, delay of application voltage and....
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Outputs from each channel are fed to the two inputs of ICl connected as a differential amplifier. IC2 and 3 are driven by the output of ICl. Output of ICl is connected to the noninverting inputs of IC2 and 3. If the output of ICl approaches the supply rail,....
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Building a practical and usable direct conversion receiver for the 40 m CW band is not as simple as it might appear. Broadcast station signals from the adjacent 41 m band, will easily overload most direct conversion mixer designs with their unwanted (and....
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This is a one tube (6J5) plus diode (1N34) circuit that converts any 8 Mc of the new FM band to the old FM band. It is assembled on a U-shaped piece of aluminum and mounted inside the radio set. I built one using old parts and carefully followed the....
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This power supply was designed for ham-radio use and has been in operation for over 10 years. Its design is very simple and practically immune to RF. It is assembled from discrete components, being the most costly element a 600VA toroidal transformer, which....
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Here is a simple technique for measuring frequencies over quite a wide frequency range and with acceptable accuracy limits using a PC. It follows the basic technique of measuring low frequencies, i.e. at low frequency, period is measured for a complete wave....
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After one has built a QRP transmitter, it would be interesting to know the exact amount of output power. Without a power meter the peak to peak voltage Vss is measured at an 50 ohm resistance (dummy load) with the available oscilloscope. Now the power rate....
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The circuit described here is that of a metal detector. The opera- tion of the circuit is based on
superheterodyning principle which is commonly used in superhet receivers. The circuit utilises
two RF oscillators. The frequencies of both oscillators are....
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The TL081 is used as a comparator in a Wheatstone bridge circuit. When the CDS cell resistance decreases due to exposure to light, the output from IC2 cause the low-frequency oscillator (a) and (b) to generate a 10-Hz square wave, gating the 1000 Hz....
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This is a very basic power failure lighting circuit based around a relay. This simple circuit has many uses, from lighting up rooms and walkways in the case of a power failure, to monitoring and security uses. There are many different power failure circuits....
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The transmitter is a very simple crystal oscillator. The heart of the circuit is the tuned circuit consisting of the primary of the transformer and a 10p capacitor. These two components oscillate when a voltage is applied to them. The frequency is adjusted....
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An IR photodiode, which senses IR skin reflectivity as a result of increased blood volume during the periods that the heart forcibly contracts, is used to pick up a signal that is correlated with the heartbeat...
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This is a compact three transistor, regenerative receiver with fixed feedback. It is similar in principle to the ZN414 radio IC which is now replaced by the MK484. The design is simple and sensitivity and selectivity of the receiver are good. All general....
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This FET probe has an input impedance of 10 M!J shunted by 8 pF. Eliminating the protective diodes reduces this impedance to about 4 pF. The frequency response of the probe extends from de to 20 MHz ( -1 dB), although higher frequency operation is possible....
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This circuit stores a single morse code message as bits in an EPROM chip, the message is sent to a relay which can key a CW transmitter. The keyer can output either a one-shot message such as "CQ DX DE CALLSIGN", or a continuous message. The continuous mode....
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You can make your own 2-meter "rubber duckies" that will likely perform much better than many commercial units. I compared my design with two other "rubber duckies" of the TH215 and ICT7 which outperformed them both. With the "duckie" of the ICT7e as much as....
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The circuit in Figure 1 represents an attempt to combine the best of both worlds: the simplicity of a rotary interface and the performance of a digital potentiometer...
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RealView is a measurement application, which records and plots measured values from analogue hardware devices in real-time. Several curves can be plotted into a single diagram. Several diagrams can be arranged on one or more pages if necessary. Plot options....
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This thermometer is capable of measuring temperatures from - 30 to +120 °F. A diode-connected 2N3904 transistor form..
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This function generator, with an adjustment range in excess of 1,000,000 to 1, uses a CA3160 BiMOS op amp as a voltage follower, a CA3080 OTA as a high-speed comparator, and a CA3080 as a programmable- current source. Three variable capacitors, C1, C2, and....
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A positive transient, such as the power switch closing, charges r through L to a voltage above the supply voltage, if Q is sufficient. When the current reverses, the diode blocks and triggers the SCS. As the capacitor discharges, the anode gate....
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This unit uses a Nicad battery to provide power to an emergency lighting setup. When power fails, T1 beco..
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This oscillator-driver produces a deafening sound of about 3 kHz, modulated with a 10-Hz warble. BZ1 is a Matsushita EFB-RP3..
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This smoke detector uses a MEM 817 p-channel enhancement mode MOSFET as its buffer amplifier. Operation of the sensor is based on a decrease in the current when smoke enters the chamber, thereby causing a negative voltage excursion at the gate of the....
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The main objective of this system is to transmit message or text through ordinary Land Line Telephone from one end (source) to another end (designation). This is get achieved by the DTMF technology. It has two sections one for editing the text and to....
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Relays are devices which allow low power circuits to switch a relatively high Current/Voltage ON/OFF. For a relay to operate a suitable pull-in & holding current should be passed through its coil. Generally relay coils are designed to operate from a....
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Ions are defined as electrically charged atoms. Positively charged ions have a deficiency of electrons, and negatively charged ions have a surplus of electrons. An ion can also be classified as an atom or molecule with an electrostatic charge. Another....
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This circuit is a Single chip metal detector.Actually we can use this one to detect metals.Specially,I think you have seen some army soldiers keep some thing to detect metals.That equipment has been made through this circuit.so you also can use this to....
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No Description available...
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This circuit is intended to drive the various lights decorating the crib prepared during Christmas season at many homes in Latin Countries, especially for children delight, in order to obtain realistic light-effects...
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A circuit stabilizes the current-transfer ratio (CTR) of an optically coupled isolator used as a linear transducer. The optocoupler produces a voltage output that is proportional to—but electrically isolated from—the voltage input. However, the output....
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The CFL-2 is an electronic ballast design for driving
a 42 watt compact fluorescent lamp from a
120 or 230 volt AC line. The circuit was designed
using the IR2156 Ballast Driver IC. The main
features of the circuit are programmable frequency,
preheat....
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The first circuit energizes the relay when the temperature rises above the preset level. The second circuit energizes the relay when the temperature falls below the preset level. The two circuits are practically identical. The only difference between them is....
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This 5-V circuit utilizes a servo-controlled dc/dc converter to generate the compliance voltage necessary for loop-..
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This is a very simple to implement Temperature Sensor. It uses LM35DT as a semiconductor temperature sensor which operates with a +5 volt DC.
It produces an analog output voltage, proportional to the change in surrounding temperature in Celsius scale....
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The amplifier drives the base of a common emitter PNP MPS6517 operating with a voltage gain of about 20. RL control varies the quiescent point of the transistor Q, so that varying amounts of signal exceed the level of V r, diode D 1 rectifies the positive....
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After one cycle of operation, SCR 1 will be on, and a low value of voltage is applied to the UJT emitter circuit, interrupting the tuning function. When pushbutton SI is pushed, or a positive going pulse is applied at point A, SCR 2 will turn on, and SCR 1....
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First circuit is for connecting VGA card to video projector or a monitor which accept VGA card frequencies and has RGB + Composite sync input. This circuit has been succesfully used with Electrohome Projection Systems ECP 4100 data and video projector. This....
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The circuit is based around LM4702 manufactured by NATIONAL semiconductors MJ11029-MJ11028 by ON semiconductors It is a high fidelity audio power amplifier. Designed for demanding consumer and pro-audio applications. You can also use this circuit with AV....
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The TDA7294 is a Hi-Fi amplifier and can give 100W RMS but with 10% distortion. Supplying 30 Volts you can have 50 Watts RMS with 1% distortion. Frequency range start at 16Hz and can reach 100KHz. Make sure you are using good heatsink. The chip supports mute....
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The control circuit operates to double from a positive supply, which, when turned on the power of the first door. and goes off when the first drain as shown in FIG. This circuit integrates the LM123, a three-terminal positive regulator and a dc dc +....
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The LM318 op amp is operated as a standard non-inverting amplifier. Resistor Rl (47 k ohm) provides an input path to ground for the bias current of the non-inverting input. The combination of R2 (560 ohm) and C2 (10 /iF) provides a frequency roll-off below....
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This small receiver with reduced range (weight 9g, dimensions 32 x 25 mm) is suitable for slow-flyer, little boats, etc...
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The idea behind this snore alarm, is just to rouse the snorer, not the entire household. To wake the sleeper, vibration is used, not an audible alert. The vibration is provided by a small motor housed in a small 35mm film case, which can be placed under the....
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The transformer has a 240V primary and has a secondary rated 24V at 2A. The bridge rectifier contains 4 diodes, their current rating needs to be high with respect to the transformers output current; if not the current may damage the diodes. I used MR751....
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A very simple circuit, that will find application in the case where you have a lot of telephones installed on a telephone line and would want to know if somebody of them is open. Thus you will not be off any discussion. Simultaneously it can cut the certain....
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The two neon bulbs will light when more than 100 V is across the ringing circuit. The bulbs provide line isolation between the unit and the telephone line. Finally, they act as a voltage divider for the bridge rectifier made up of D 1 through D4. That....
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The RGB blue box turns your PC"s RGB-monitor screen blue at the flip of a switch. That is, it makes your computer display bright white text on a blue background, instead of the usual low-intensity white on black. The RGB .blue box connects between your....
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This is a novel flasher circuit using a single driver transistor that takes its flash-rate from a flashing LED. The flasher in the photo is 3mm. An ordinary LED will not work. The flash rate cannot be altered by the brightness of the high-bright white LED....
The Hand Steadiness Tester is a game which tests the steadiness of your hand. The player has to take the ring from one end to another end without touching it to the wire. In this the player gets 4 turns. If the player touches the wire 4 times he has to reset....
An ultra-low-noise, low-distortion op ampthe AD797is combined with the ADS 11 op amp, which offers a high bandwidth and a 100-mA output drive capability. The composite-amplifier circuit serves quite well when driving high resolution ADC`s and ATE systems.....
The watchdog timer contains a counter, IC3, in addition to the usual retriggerable 555 timer, ICl. The counter will so..
This IC chip was designed specifically for use in power boosting applications in automobiles. It is self protecting against short circuits and thermal problems. In the bridge configuration shown it will deliver 20 watts of power into a 2 ohm speaker....
This is a classic signal mixer that is used for audio purpose. VR1 & VR2 are inputs audio volume controlers and VR3 is used to control the balance between Input1 and Input2. connect a dynamic microphone to Input1 and a music without vocal to Input2, then....
The application that to you we propose is a simple filter of region that limits the acoustic region (20-20000Hz) in the region 20-100Hz. With the manufacture that to you we propose you can make a active filter in order to you lead a loudspeaker of very....
This is a selection of small self-contained alarm circuits. They have a very low standby current; and are suitable for battery operation...
The 15v zener is fed via the 4K7 resistor from the input. With 0.6v across the base - emitter of the PNP transistor, this establishes a voltage of 14.4 across the 3K3, so there must be a current of nearly 4.4mA through the 3K3. This current is available to....
This circuit is a high performance charger for gelled electrolyte lead-acid batteries. Charger quickly recharges battery and shuts off at full charge. Initially, charging current is limited to 2A. As the battery voltage rises, current to the battery....
A few months ago as I was surfing on the net, I saw an oscilloscope based on PIC18F2550 microcontroller and a KS0108 controller based graphical LCD. That was Steven Cholewiak's web site. I had never seen before so amazing microcontroller-only oscilloscope.....
The circuit uses independent timers to flash two light emitting diodes. Any time that light emitting diode D1 is lit__light emitting diode D2 will be switched off. Light emitting diode D3 is on if both D1 and D2 are off. Two versions of the circuit are....
Video designs are often pressed to operate on the lowest possible rail voltagesa simple result of the trend towards lower voltage logic and the advantages of sharing supply potentials wherever possible...
Most of the transistors in this speaker protector function as switches. Normally, Q4, Q5, and K1 are on and the speakers are connected to the amplifier. However, if a large dc voltage appears at an amplifier output, either Q3, or Ql and Q2 turn on, biasing....
This transmitter can be tuned to the FM broadcast band, 2 meters,-or other VHF bands by changing C5 and Ll. The values given for C5 and Ll will place the frequency somewhere in the FM broadcast band. Ll is 4 turns of #20 enameled wire airwound, % inch in....
TimeGen is an engineering CAD tool which allows an engineer the capability to quickly and effectively draw timing diagrams. The waveforms can easily be exported to other Window programs, such as Microsoft Word, for use in writing design specifications.....
To decouple the sensors from the meter amplifier, either a reference junction at ooc or a bucking voltage set at room temperature may be used. The latter method is simpler, but is sensitive to changes in ambient temperature. ..
This is a circuit for a game of the shooting gallery variety. IC2a and b form an astable multivibrator clocking ICl which causes LEDs 1-8 to flash in turn LED 5 is the target LED and the object of the game is to depress PBI just as LED 5 comes on. If this is....
Using an RC oscillator, an up to 24-stage ripple counter O) 16777216 or 2U, and a 0.1-Hz count-rate with #..
Rosemary's original test circuit is shown in the article she tried to have published in a "refereed" scientific journal, but the submission was always rejected. In the last 5 months, I have had extensive email correspondence, and numerous telephone....
The circuit in Figure 1 is an RS-232/485 converter that uses the transmitted signal itself to control the flow. The circuit uses MAX232 and MAX483 interface circuits, IC1 and IC2 from Maxim Integrated Products (http://www.maxim-ic.com) to convert between the....
A Class A // Class AB amplifier rated 100 Watts when driving a 4 ohm loudspeaker. This circuit developed out of my 30+ years of JLH class-A based investigations. The original `simple` 1969 JLH class-A design provided excellent first cycle accuracy through....
The amplifier"s gain is nominally 20 dB. Its frequency response is determined primarily by the value of just a few components-primarily C1 and Rl. The values in the schematic diagram provide a response of ±3.0 dB from about 120 to over 20,000 Hz.....
The input impedance is the value of potentiometer Rl. If your instrument has extra-deep bass, change capacitor Cl to 0.5 mF. What appears to be an extra part in the feedback loop is a brightening tone control. The basic feedback from the op amp's output (pin....
Except for the coupling and decoupling capacitors, IC1 is a complete wideband amplifier that has a fixed gain of 20 dB to 450 MHz. No external compensation is required. since the NE5205 functions as a gain block, two or more cart be easily cascaded to....
The buck-boost configurationnf the MAX634 is well suited for dual output de-de converters. Only a second winding on the inductor is needed. Typically, this second winding is bifilar-primary and secondary are wound simultaneously using two wires in....
Process-control applications often require a monostable multivibrator (one-shot) with a pulse width that c..
The circuit receives its power from a 15-V wall adapter (not shown). The circuit takes advantage of the fact that th..
A minimum number of parts yields a compact switching converter that can provide sufficient voltage to drive white LEDs. The resulting lamp is much more efficient, in terms of lumen hours per pound of battery, than incandescent bulbs, and because the color of....
Light emitting diodes are advan- tageous due to their smaller size, low current consumption and catchy colours they emit. Here is a running message display circuit wherein the letters formed by LED arrangement light up progressively. Once all the letters of....
C ircuit of a new type of remote control switch is described here. This circuit functions with inaudible (ultrasonic) sound. Sound of frequency up to 20 kHz is audible to human beings. The sound of frequency above 20 kHz is called ultrasonic sound. The....
In the circuit in Fig. 1, ICla produces the integral term required but also has the side effect of producing a proportional term not required, so this term is subtracted by IClb leaving a pure integral. If the ratio R2/R5 does not exactly match the ratio of....
This circuit is not open for discussion. Although working perfectly, it was experimental. I will answer no emails in regards to this circuit. If you are looking for a more serious and reliable bug detector, go to the Countersurveillance Monitor article on....
A simple solenoid driver uses incandescent lamp filaments as on-indicators to limit power consumption. High magnetic reluctance (opposition to flux) in the coil of an armature-driven device, such as a solenoid or relay, calls for a surge of activation....
A time delay relay is a relay that stays on for a certain amount of time once activated. This time delay relay is made up of a simple adjustable timer circuit which controls the actual relay. The time is adjustable from 0 to about 20 seconds with the parts....
This neat little circuit can play 8 note tunes at any speed you want. You select the notes with 8 trim pots. The speed in selected through a ninth pot. The circuit draws very little power and can be powered by a 9 volt battery, with the addition of a 7805....
A variable dock-pulse generator is made up of two sections of IC1 (a 4069 CMOS hex inverter). Rl, Sl, and capacitors Cl through C6. By adjusting Rl and switching one of the capacitors into the circuit, the clock"s pulse rate can be varied over a wide....
The 12 Volt power in my application comes from a small solar power system, it may also be provided by a suitable wall-wart DC power supply. The cistern is located below the toilet tank, the pump moves the water up to the toilet`s tank. The pump is switched....
A very regular configuration of the 555 astable timer to work as a timer to trigger an alarm or any other equipment connected to pin 3. R resistor should be replaced with a potentiometer that will change the time delay. Capacitor C should be calculated too....
This project is built on the third section of the PC board, identified by "SIREN" and "Project 5." You will notice the similarity between this circuit and the LED FLASHER circuit from project 2. The only differences are the LED has been removed and the 22R....
Six preset controls and seven selector switches enable a vast range of different sounds to be produced and altered at will. Such sounds as steam trains chuffing, helicopters flying, bird chirping, and machine guns firing are possible, as well as the usual....
This type of design can produce a very high amperage current for a faction a second that can used to do some useful work if properly harnessed. The switching device could be a rotating spark gap as used by Nikola Tesla or some high speed electronic device,....
The single-chip, burglar -alarm circuit shown uses a dual 556 timer, draws 10 mA of standby current, and generates a pulsing alarm signal that conserves battery energy. Once activated, the alarm wilLremain on, independent of the subsequent state of any of....
This Cheap circuit will amaze you with its wide range recieving signal between 6 and 17Mhz (49-19meters). Power supply is not necesery, just connect it to your pc, place the antena to your home piping network and voila!..
This box is a portable transfer standard to maintain and carry with you a local time signal of 59 short beeps (pips) plus a long 0.4 sec beeeeep on the full minute. At the start of the job, the box is started by manually synchronising it by ear with a....
This is a circuit to use a standard, low quality opto isolator to transfer an analogue signal with reasonable linearity and without complicated feedback loops to monitor and linearise it. The circuit was designed to interface a mains driven thryristor motor....
This circuit has high output only when all three inputs are high. The noninverting-input current, when all thre..
TheCA3189E is a comprehensive FM-IF system designed for high fidelity FM tuners. It includes a three stage FM-IF amplifier/limiter configuration with level detectors for each stage, a double-balanced quadrature FM detector and an audio amplifier that....
The GPS is based on 24 satellites located in six orbital planes at a height of 20 200 km and circle the Earth every 12 h. Each plane is inclined at 55 to the Earth’s equator and contains four satellites. The GPS positioning is based on oneway time-of-arrival....
This stero amp will give you 4-8W/ch of zero feedback triode power for less than a pair of Chinese 300B's ...if you know where to shop. For those of you who are unfamiliar with this lil' tube here's the poop: The 5687 is a 9-pin miniature twin triode (a la....
The interest for circuits of tubes, remains big. Thus I will give completed in enough big degree, circuit of preamplifier. It is mainly constituted by the department of main preamplifier, the department of input selector, delay of application voltage and....
Outputs from each channel are fed to the two inputs of ICl connected as a differential amplifier. IC2 and 3 are driven by the output of ICl. Output of ICl is connected to the noninverting inputs of IC2 and 3. If the output of ICl approaches the supply rail,....
Building a practical and usable direct conversion receiver for the 40 m CW band is not as simple as it might appear. Broadcast station signals from the adjacent 41 m band, will easily overload most direct conversion mixer designs with their unwanted (and....
This power supply was designed for ham-radio use and has been in operation for over 10 years. Its design is very simple and practically immune to RF. It is assembled from discrete components, being the most costly element a 600VA toroidal transformer, which....
Here is a simple technique for measuring frequencies over quite a wide frequency range and with acceptable accuracy limits using a PC. It follows the basic technique of measuring low frequencies, i.e. at low frequency, period is measured for a complete wave....
After one has built a QRP transmitter, it would be interesting to know the exact amount of output power. Without a power meter the peak to peak voltage Vss is measured at an 50 ohm resistance (dummy load) with the available oscilloscope. Now the power rate....
The circuit described here is that of a metal detector. The opera- tion of the circuit is based on superheterodyning principle which is commonly used in superhet receivers. The circuit utilises two RF oscillators. The frequencies of both oscillators are....
The TL081 is used as a comparator in a Wheatstone bridge circuit. When the CDS cell resistance decreases due to exposure to light, the output from IC2 cause the low-frequency oscillator (a) and (b) to generate a 10-Hz square wave, gating the 1000 Hz....
This is a very basic power failure lighting circuit based around a relay. This simple circuit has many uses, from lighting up rooms and walkways in the case of a power failure, to monitoring and security uses. There are many different power failure circuits....
The transmitter is a very simple crystal oscillator. The heart of the circuit is the tuned circuit consisting of the primary of the transformer and a 10p capacitor. These two components oscillate when a voltage is applied to them. The frequency is adjusted....
An IR photodiode, which senses IR skin reflectivity as a result of increased blood volume during the periods that the heart forcibly contracts, is used to pick up a signal that is correlated with the heartbeat...
This is a compact three transistor, regenerative receiver with fixed feedback. It is similar in principle to the ZN414 radio IC which is now replaced by the MK484. The design is simple and sensitivity and selectivity of the receiver are good. All general....
This FET probe has an input impedance of 10 M!J shunted by 8 pF. Eliminating the protective diodes reduces this impedance to about 4 pF. The frequency response of the probe extends from de to 20 MHz ( -1 dB), although higher frequency operation is possible....
This circuit stores a single morse code message as bits in an EPROM chip, the message is sent to a relay which can key a CW transmitter. The keyer can output either a one-shot message such as "CQ DX DE CALLSIGN", or a continuous message. The continuous mode....
You can make your own 2-meter "rubber duckies" that will likely perform much better than many commercial units. I compared my design with two other "rubber duckies" of the TH215 and ICT7 which outperformed them both. With the "duckie" of the ICT7e as much as....
RealView is a measurement application, which records and plots measured values from analogue hardware devices in real-time. Several curves can be plotted into a single diagram. Several diagrams can be arranged on one or more pages if necessary. Plot options....
This thermometer is capable of measuring temperatures from - 30 to +120 °F. A diode-connected 2N3904 transistor form..
This function generator, with an adjustment range in excess of 1,000,000 to 1, uses a CA3160 BiMOS op amp as a voltage follower, a CA3080 OTA as a high-speed comparator, and a CA3080 as a programmable- current source. Three variable capacitors, C1, C2, and....
A positive transient, such as the power switch closing, charges r through L to a voltage above the supply voltage, if Q is sufficient. When the current reverses, the diode blocks and triggers the SCS. As the capacitor discharges, the anode gate....
This unit uses a Nicad battery to provide power to an emergency lighting setup. When power fails, T1 beco..
This oscillator-driver produces a deafening sound of about 3 kHz, modulated with a 10-Hz warble. BZ1 is a Matsushita EFB-RP3..
This smoke detector uses a MEM 817 p-channel enhancement mode MOSFET as its buffer amplifier. Operation of the sensor is based on a decrease in the current when smoke enters the chamber, thereby causing a negative voltage excursion at the gate of the....
The main objective of this system is to transmit message or text through ordinary Land Line Telephone from one end (source) to another end (designation). This is get achieved by the DTMF technology. It has two sections one for editing the text and to....
Relays are devices which allow low power circuits to switch a relatively high Current/Voltage ON/OFF. For a relay to operate a suitable pull-in & holding current should be passed through its coil. Generally relay coils are designed to operate from a....
Ions are defined as electrically charged atoms. Positively charged ions have a deficiency of electrons, and negatively charged ions have a surplus of electrons. An ion can also be classified as an atom or molecule with an electrostatic charge. Another....
This circuit is a Single chip metal detector.Actually we can use this one to detect metals.Specially,I think you have seen some army soldiers keep some thing to detect metals.That equipment has been made through this circuit.so you also can use this to....
This circuit is intended to drive the various lights decorating the crib prepared during Christmas season at many homes in Latin Countries, especially for children delight, in order to obtain realistic light-effects...
A circuit stabilizes the current-transfer ratio (CTR) of an optically coupled isolator used as a linear transducer. The optocoupler produces a voltage output that is proportional to—but electrically isolated from—the voltage input. However, the output....
The first circuit energizes the relay when the temperature rises above the preset level. The second circuit energizes the relay when the temperature falls below the preset level. The two circuits are practically identical. The only difference between them is....
This 5-V circuit utilizes a servo-controlled dc/dc converter to generate the compliance voltage necessary for loop-..
This is a very simple to implement Temperature Sensor. It uses LM35DT as a semiconductor temperature sensor which operates with a +5 volt DC. It produces an analog output voltage, proportional to the change in surrounding temperature in Celsius scale....
The amplifier drives the base of a common emitter PNP MPS6517 operating with a voltage gain of about 20. RL control varies the quiescent point of the transistor Q, so that varying amounts of signal exceed the level of V r, diode D 1 rectifies the positive....
After one cycle of operation, SCR 1 will be on, and a low value of voltage is applied to the UJT emitter circuit, interrupting the tuning function. When pushbutton SI is pushed, or a positive going pulse is applied at point A, SCR 2 will turn on, and SCR 1....
First circuit is for connecting VGA card to video projector or a monitor which accept VGA card frequencies and has RGB + Composite sync input. This circuit has been succesfully used with Electrohome Projection Systems ECP 4100 data and video projector. This....
The circuit is based around LM4702 manufactured by NATIONAL semiconductors MJ11029-MJ11028 by ON semiconductors It is a high fidelity audio power amplifier. Designed for demanding consumer and pro-audio applications. You can also use this circuit with AV....
The TDA7294 is a Hi-Fi amplifier and can give 100W RMS but with 10% distortion. Supplying 30 Volts you can have 50 Watts RMS with 1% distortion. Frequency range start at 16Hz and can reach 100KHz. Make sure you are using good heatsink. The chip supports mute....
The control circuit operates to double from a positive supply, which, when turned on the power of the first door. and goes off when the first drain as shown in FIG. This circuit integrates the LM123, a three-terminal positive regulator and a dc dc +....
The LM318 op amp is operated as a standard non-inverting amplifier. Resistor Rl (47 k ohm) provides an input path to ground for the bias current of the non-inverting input. The combination of R2 (560 ohm) and C2 (10 /iF) provides a frequency roll-off below....
This small receiver with reduced range (weight 9g, dimensions 32 x 25 mm) is suitable for slow-flyer, little boats, etc...
The idea behind this snore alarm, is just to rouse the snorer, not the entire household. To wake the sleeper, vibration is used, not an audible alert. The vibration is provided by a small motor housed in a small 35mm film case, which can be placed under the....
The transformer has a 240V primary and has a secondary rated 24V at 2A. The bridge rectifier contains 4 diodes, their current rating needs to be high with respect to the transformers output current; if not the current may damage the diodes. I used MR751....
A very simple circuit, that will find application in the case where you have a lot of telephones installed on a telephone line and would want to know if somebody of them is open. Thus you will not be off any discussion. Simultaneously it can cut the certain....
The two neon bulbs will light when more than 100 V is across the ringing circuit. The bulbs provide line isolation between the unit and the telephone line. Finally, they act as a voltage divider for the bridge rectifier made up of D 1 through D4. That....
The RGB blue box turns your PC"s RGB-monitor screen blue at the flip of a switch. That is, it makes your computer display bright white text on a blue background, instead of the usual low-intensity white on black. The RGB .blue box connects between your....
This is a novel flasher circuit using a single driver transistor that takes its flash-rate from a flashing LED. The flasher in the photo is 3mm. An ordinary LED will not work. The flash rate cannot be altered by the brightness of the high-bright white LED....
