New Circuits Page 200
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The input signal is amplified by the transistors. The distorted output is then clipped by the two diodes and the high frequency noise is filtered from the circuit via the 500 pF capacitor..
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This is the fully featured, jammed packed temperature readout unit. I can measure temperature from up at 8 DS1820 digital temperature sensors all on the same 1-wire bus. That's right only 3 wires are needed to go to all the temperature sensors, GND, VCC and....
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I use this power supply for applications that doesn't use too mucho power. It can provide power to circuit that uses less than 100mA without any problem. The disadvantage of this circuit is the danger of an electrical shock, so it cannot be used if the....
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The problem with using two zeners back to back in series to get symmetrical clamping is that the knee of the..
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An FM regenereative receiver using a single FET and one audio amplifier IC...
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This circuit is a simple wire loop alarm that can be used in doorways, hallways, or any other place the tripwire will be broken by intruders. The circuit has a built in siren, but it can be replaced by a relay to drive an external siren, commercial alarm, etc...
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This circuit, instead of dividing by an integer, divides the input signal by +1/2. With the feedback connections ..
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U1a operates as a low-noise microphone preamp. Its gain is only about 3.9 because the high output impedance of the drain of the FET inside the electret microphone causes U1a?s effective input resistor to be about 12.2K. C2 has a fairly high value in order to....
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This GPS receiver is powered by 2 AA batteries. They are only strong enough for the GPS to stay on for about two hours, and this seems like quite a waste. I would like to be able to use a larger battery, and sometimes even an AC adapter...
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WinCircuit is a software of realization of drawing of printed circuit in single or double layers. Principal qualities are the facility of use and the sight in pseudo 3D which gets a vision of the circuit close to reality...
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This Design Note describes how to generate five separate
output voltages using the LTC®1538-AUX, a dual synchronous
switching regulator controller with internal circuitry
adaptable to many additional configurations...
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At this circuit the SSM2044 IC is used, a 4 pole voltage controlled filter designed for electronic music applications. On-chip voltage control of resonance allows direct and easy interfacing with programmers and controllers. The IC features extended control....
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Ql and Q2 constitute a simple, high-speed FET input buffer. Ql functions as a source follower, with the Q2 current source load setting the drain-source channel current. The LT1010 buffer provides output drive capability for cables or whatever load is....
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The meter reading is directlyjproportiona! to the logarithm of the input light power. The logarithmic circuit behavior arises from the nonlineardiode pnjunction current/voltage relationship..
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Antennas that are much shorter than 1/4 wavelength present a very small and highly relative impedance that is dependent on the received frequency. It is difficult to match impedances over a decade of frequency coverage. Instead, input stage Q1 is an FET....
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Our present car controller runs on a single PIC16F870 micro and provides functions for remote door locks, headlight reminder, and car finder. It is constructed using wire-wrap to allow for future expansion and is mounted using Velcro on the passenger side....
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R1 and R2 form a voltage divider, insuring that the phone line sees a high impedance load and that high voltages (such as the ring voltage) are easily dissipated by the protective diodes (CR1 and CR2). Also (obviously) they serve to divide all incoming....
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This metal detector circuit needs to be powered using a 9 volts power supply ( DC) or a 9 volts battery .
The C1 capacitor is a variable capacitor with a value of 365 pF , C2 is a 100pF silver mica capacitor , C3 is a 0.05 uF disc capacitor and the C4 is....
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This circuit must be connected to a 5 volt DC source. See my RR page for several 5 volt supplies. Note the flashing LED is optional, but looks s-o-o-o-o good on the top of a locomotive...
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Inserting two 1-MO resistors, R1 and R2, in the output stage of one of the circuit"s inverters limits the current needed by the oscillator tone more than a few pA. This circuit includes a CD4007 package, which has three CMOS inverters. It forms a standard....
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The logic probe can indicate four input states, as follows: floating input—all LEDs off..
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The circuit is built around a 741 general-purpose op amp that is configured as a voltage follower; with the components shown, the op amp has a voltage gain of one. The output of the 741 is used to drive a 50- meter movement. Potentiometer R7 is used to zero....
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Here is the schematic diagram for a 20 Watt driver. I developed this circuit in 1985, and used it to build a lamp that found much use both as camping light and as emergency light during the then-frequent power outages.
The two transistors work as a....
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Beeps when hears your whistle
A gadget suitable for key-holders, games etc. These devices contained a special purpose IC and therefore were not suited to home construction. The present circuit is designed around a general purpose hex-inverter CMos IC and,....
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This circuit is used to trigger a camera`s electronic shutter circuit when a flash of lightning is present. This circuit would also work for photographing fireworks displays or other events involving flashes of light...
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Input 1 is used as a gating period, during which a single rising edge on input 2 will cause a logic 1 output-any other number, indicating non-identical frequencies causes a logic 0 output. ICla converts input 1 to a narrow pulse which initializes IC2 which....
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A circuit for multiplying the width of incoming pulses by a factor greater or less than unity is simple to build and has the feature that the multiplying factor can be selected by adjusting one potentiometer only. The multiplying factor is determined by....
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A preamp designed for the minimalist, and having no frills at all is the design goal for this project. It is designed as a preamp for the Death of Zen (DoZ) Class-A power amp (Project 36), and has very low levels of noise and distortion, in a minimum....
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This circuit has read the RIAA equalization, tone controls, and adequate gain to drive most power amplifiers conunercial by using CA3410 op amp BiMOS. Total harmonic distortion, pushed to provide an output of 6-V, is less than 0.035% in audio-frequency range....
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The circuit is based on asynchronous decade counter 7490(IC2), a 7 segment display (D1), and a seven segment decoder/driver IC 7446 (IC1).The seven segment display consists of 7 LEDs labelled a through g. By forward biasing different LEDs, we can display the....
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This project is intended for controlling mains powered disco lighting, although there are many other possible uses for controlling almost any mains appliance. It will control five seperate channels at up to 3 Amp per channel. This could be increased by....
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Using an intersil ICL 7106 A/D converter chip and an LED display module, this gauge uses a Sensym Corp. pressure tra..
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Low-cost microprocessor supervisors reset controllers when power-supply voltages fall below given levels. As added protection, you can also reset the microcontroller when the power supply is too high by combining a low-cost shunt-voltage regulator with a....
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The circuit shown in Figure 1 is specifically designed to
control a single 1W CCFL. T1, Q1, Q2 and associated
components form a current fed resonant Royer converter
that produces a high voltage at transformer T1s secondary
winding. The CCFL current is....
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Most products use multiple LEDs to provide adequate backlight for a display. Because the LED`s brightness depends on its forward current, these multiple diodes commonly connect in series to ensure that the same current flows through each of them. You need....
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The transmitting section of this infrared tx-rx is unusually simple but it works rather well: the infrared LED pulses at a frequency of 160Hz and its range, with its receiver, is between 2 and 4m depending on the transformer used and the setting of the 100k....
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Recent innovations in process and circuit design have
enabled the release of three new RS485 transceivers: the
LTC®1481, LTC1483 and LTC1487. These devices share
an improved receiver circuit which features 80mA quiescent
current operation (driver....
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The first amplifier circuit is a bird phone. In this circuit, the electret mike (MIC1) is mounted in the neck of a large plastic funnel. The amplifier, built around an MC34119 (which is available from D.C. Electronics, P.O. Box 3203, Scottsdale, AZ....
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This circuit uses three easily available 555 timer ICs. All three work as astable multivibrators. The first 555 has an on period and off period equal to 1 sec. This IC controls the on/ off periods of the other 2 555s which are used to flash two bulbs through....
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This frequency doubler using a single 4069 hex inverter IC, a frequency doubler can be constructed to give an output pulse train whose frequency is twice that of a squarewave input signal. The signal is applied to the input of N1. It should be a squarewave....
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The swept-frequency oscillator offers an inexpensive source of discrete frequencies for use in testing digital circuits. In this configuration, the circuit generates an 80-second seguence of eight frequencies, dwelling for 10 seconds on each frequency. You....
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A 0 to 2 MHz ferquency meter with a Minimum Mass Wireless Coupler, based on the ATMega8.Range to the Minimum Mass Base Unit is 10 to 15 cm. Since the frequency meter is battery operated, it can be floated from ground, making life in and around the test bench....
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The logic input is applied to opto-isolators Ul and U2 with, respectively, npn and pnp emitter follower outputs. Dc balance is adjusted by potentiometer R2. The emitter followers drive the gates of Ql and Q2, the complementary TMOS pairs. With a ±12 V....
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A gas sensor (TGS823 from Allegro Electronics, Cornwall Bridge, CT 06754) conducts in the presence of explosive gases. U5 is a voltage-to- frequency converter that produces a frequency proportional to the sensor conductance. The output frequency ranges from....
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An LM317 voltage regulator is configured as a constant-current source. It is used to supply the 50 mA charging current to S01-S06, an array of AA-cell battery holders. Each of the battery holders is wired in series with an LED and its associated shunt....
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At this voltage regulator prototype the maximum current, with output shortcircuited it was only 0,5 A, so no overheating occured.
In this dc voltage regulator circuit, T1 is for current limitation. As soon as the voltage on the R2+R3 becomes higher than....
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These units can be useful as a short-range, single-channel remote-control. When the pushbutton in the transmitter circuit is briefly activated, the LED D1 in the receiver illuminates and an optional beeper or relay can be operated. Circuit operation is based....
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This circuitry offers some features that are highly desirable when building a QRP (or ANY) transceiver. It also includes a combination of features that many might not always take the time to include in their projects. Considerable effort has been made to....
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Insulated-gate, field-effect transistor (IGFET), Q2 and silicon photo cell Zl form the heart of this circuit. Transformer T1 is an audio-output type, but it"s reversed in the circuit. A sudden flash from a photoflash unit detected by Zl sends a voltage....
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If you've crossed the line and play guitar or bass and also sing in a band, you're almost certain to have run into the situation that you step away from the mike to do a solo (or one of those neato, expressive dance steps, or a facial impression of the pain....
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This circuit monitors the power-line (ac) voltage. When a power failure occurs, on restoration of power, the circuit a..
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A cathode follower based on the 6BL7 or 6BX7 is ideal for output. I used a mu-follower circuit with no feedback, a 12SN7 as the gain stage, and a 6BL7 as the cathode follower/current source. (I have many old GEs I wanted to use, and converting to 6SN7 means....
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The object is to get the cell voltage high enough for the sulphate to dissolve without boiling or melting the battery. This is achieved by applying higher voltage for shorter periods and let the battery rest for a while. The pulses on short range is about....
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This circuit can be built small enough to frt inside a toy. The circuit consists of a relaxation oscillator utilizing one unijunction transistor (2N2646, MU10, TIS43). R2 and C2 determine the frequency of the tone. Pushing the button, SW1 charges up the....
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Integrated circuit Ul (a 555 oscillator/timer) is wired as a conventional pulse generator. The frequency of the pulse generator is controlled by potentiometer Rll. Resistor R2 puts areasonable limit on the highest speed attainable. The output of the pulse....
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The positive and negative peak amplitude is controllable to an accuracy of about ± 0.01 V by a dc input. Also, the output frequency and symmetry are easily adjustable. The oscillator consists of an integrator and two comparators—one comparator sets the....
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The basic VFC (voltage-to-frequency converter) in Figure 1 comprises an integrator (IC1) and a Schmitt-trigger circuit (IC2). The integrator converts the dc input voltage, VIN, to a linear voltage ramp, and the Schmitt trigger sets the limits of the....
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This simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input. It is therefore extremely useful for powering opamp and other circuits that require a dual voltage from a single battery. The circuit will....
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This method is sometimes impractical, however, because it cannot check for short circuits. The method shown in Figure 1 solves the short-circuit problem. Connecting LED indicators at each shorting loop provides a visual indication. The beauty of this scheme....
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Using the software during flight simulation models of planes: REAL-FLIGHT, we first chose a housing of any transmitter empty direct connection potentiometers innings. However this is not good because, first races of the potentiometers are only 90 degrees,....
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Crosstalk from digital data signals into the clock signal of a data-conversion system can cause hard-to-diagnose problems. This obscure problem is different than the crosstalk from digital data signals into the analog signal path, which was the subject of....
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The very simple circuit uses only two CD4001 packages, i.e., eight NOR gates and operates in the following way: Pulse streams are fed to an RS flip flop generating an output waveform wliich has a small or large duty cycle depending on the direction of....
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This project is useful if you wish to experiment with absolute phase, or are just interested in the possibilities of a polarity reversal circuit. In the case of absolute phase, many studies have shown that there can be an audible difference between....
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A 6 V battery can provide 100-150 Vdc center-tapped at a high internal impedance (not dangerous though it can inflict an unpleasant jolt). A 6.3 V transformer is connected ' 'in reverse'' with a transistor used in a Hartley oscillator configuration. The....
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The telephone-line tester consists of nothing more than a meter (that`s used to measure line voltage in the on- and off-hook state), three resistors (one of which is variable), a pushbutton switch, and a modular telephone connector...
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No description available...
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The dimmer circuit in Figure 1 can change the intensity of the light from zero to maximum. The dimmer operates at approximately 12V, unlike the usual ones that function by adjusting the firing angle of the 110 or 220V mains supply.
The dimmer works to....
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The incoming RGB inputs are terminated with resistors Rl, R2, and R3 and potentiometers RVl, RV2, and RV3. These provide input impedances of approximately 75 0. The presets should be adjusted to provide a maximum input of 1 V pk-pk into the MC1377. The....
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A 7 MHz oscillator with a variable crystal oscillator (VXO) operates very stably, but it allows only a small frequency variation (approx. 5 kHz). In contrast, a VFO with an LC resonant circuit can be tuned over a range of several hundred kHz, but its....
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The alarm is "set" by opening Sw1. It can be any small 1-amp single-pole change-over switch - but for added security you could use a key-switch. Once Sw1 is opened you have about 10 to 15 seconds to get out of the vehicle and close the door behind you. When....
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Because power MOSFETs offer high power gain at both audio and radio frequencies, they are useful in many areas of radio-circuit design. For rf applications, a MOSFET"s large safe operating area, V0 s vs ! 0, protects it against damage from reflected rf....
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Pulses from the distributor points are passed through a current limiting resistor, rectified, and clipped at 4 volts. Via Q1 and the diode pump, a dc voltage proportional to engine rpm is presented to RV1; the sharp transfer characteristic of a CMOS gate,....
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This self-biasing configuration is useful any time srnall changes in light level must be detected, for example, when monitoring very low flow rates by counting drops of fluid. In this bias method, the photodarlington is de bias stabilized by feedback from....
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This is a 8048/IM80C48 Microcomputer with 8 character 16-segment ASCII triplex liquid crystal display. The two bit character address is merged with the data and written to the display driver under the control of the WR line.
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This high power led mood light is based on PIC16F628 and the ability of this mcu to produce PWM pulses. Varying pulse width we can produce millions of color combinations using only the three basic colors. So only one RGB (Red-Green-Blue) led is capable....
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These ultrasonic circuits are all quite old: my notes date them at mid-70s so they don`t use ICs. Nevertheless there are several places where an op-amp would possibly simplify things. Despite their age I hope they are of interest: certainly basic principles....
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This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores), or for anything else that may be counted. The circuit accepts any TTL compatible logic signal, and can be expanded easily (see....
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The PWM controller uses complementary half-H peripheral drivers SN75603 and SN75604, with totem-pole outputs rated at 40 V and 2.0 A. These drivers effectively place the motor in a full-bridge configuration, which has the ability to provide bidirectional....
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This circuit uses the CA3207 sequence driver and CA3208 segment latch-driver in combination to drive display devices of up to 14 segments with up to 14 characters of display.
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Sounds are picked up by MIC1 and fed to the input of the first op amp. The signal is then fed to the input of second op amp Ulb, where it is boosted again by a factor of between 1 and 33, depending upon the setting of range switch Sl. With the range....
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Circuit has a 1 Hz-to-30 MHz output, 150-dB dynamic range, for a 0 to 5 V input. It maintains 0.08% linearity over its entire 71/3 decade range with a full-scale drift of about 20 ppm/°C. To get the additional bandwidth, the fast )FET buffer drives the....
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This simple circuit can color the sound coming from your audio system. Clocking for the circuit is provided by an oscillator built from one quarter of a 4093 quad NAND Schmitt trigger. With the component values shown, it will run at about 5 Hz. The....
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The most popular LCD interface is the Hitachi 44780 based LCD controller chip which provides a fairly easy to work with interface and low power consumption. The major drawback of the interface is the perceived complexity of working with the interface. This....
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This relatively simple, inexpensive circuit requiring one trimming operation can multiply or divide with a consistentaccuracy of greater than 1 part in 1,000. An inexpensive CMOS version of standard 555 timer chip T, in conjunction with low-drift LMll....
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Applying voltage to the circuit triggers SCR1. With SCRl on, the voltage on the anode of SCR2 rises until SCR2 triggers to commu-tate SCRl. The voltage on the gate of SCRl will swing negative at this time, and only after a positive potential of 0 volt is....
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The Dallas Semiconductor (www.dalsemi.com) DS1722 digital thermometer allows measurement resolution as fine as 0.0625°C in digital form and with linear response. The accuracy specification is only 2°C, but you can improve this figure by careful calibration.....
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S/PDIF is an acronym for Sony /Philips Digital Interface (or Sony /Philips Digital Interconnect Format). The full specification for the S/PDIF interface consists of hardware and software, but only the hardware side will be discussed here - the software is....
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This DC-DC converter ("inverter") needs nothing but unmodified Radio Shack parts. You don`t need to build or wind any coils or transformers. This is a cheap-and-dirty experimenter`s circuit. I tested this and it worked for me, but I disclaim all warranties!....
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Driving a D/A converter with an A/D converter provides an overall analog-hold function, which though limited in output resolution, offers zero voltage droop and infinite hold time. The A/D converter shown (IC1) includes a 12-bit compatible track/hold at its....
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This is the construction guide for the 5301 wideband fuel mixture display kit. The 5301 is the Tech Edge version (rather than the Jaycar version) of the modified Silicon Chip FMD design, and it features, compared to the original kit, double sided PCBs a new....
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This circuit will switch off the line supply to audio or video equipment if there has been no input signal for about 2 seconds. SI provides manual operation and S2 acts as a reset. This circuit allows for time to change a tape or compact disc. ..
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This circuit, is basically a resistance ? sensing window switch, except that the ?resistor? takes the form of an NTC thermistor and the circuit thus responds to temperature. TH1 must have a resistance in the range 500ohm - 9Kohm. RV1 is used to set half ?....
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The two basic parts for working with IR are the emitter and the detector. The emitter is typically an LED that emits near-infrared light. A typical wavelength is 880nm, which is just beyond the human eyes ability to see. Many suppliers, new and surplus, can....
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Many a times one needs an extra telephone ringer in an ad joining room to know if there is an incoming call. For example, if the telephone is installed in the drawing room you may need an extra ringer in the bedroom. All that needs to be done is to connect....
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The aim of this design is to reproduce a Combo amplifier of the type very common in the `sixties and the `seventies of the past century. It is well suited as a guitar amplifier but it will do a good job with any kind of electronic musical instrument or....
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This amplifier delivers 20 W into an 8-D load using a single IRF520 driving a transformer coupled output stage. This circuit is similar to the audio output stage used in many inexpensive radios and phonographs. ..
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This circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. The device formed by Q1, Q2 and related resistors triggers the SCR. Timing is provided by R1, R2 & C1. To change flashing frequency....
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Most of the power supply failure indicator circuits need a separate power supply for themselves. But the alarm circuit presented here needs no additional supply source. It employs an electrolytic capacitor to store adequate charge, to feed power to the alarm....
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The circuit in Figure 1 provides a simple and inexpensive way to protect one of the most valuable components in portable applications: the battery. Applications include all portable equipment that requires a limited time of operation, such as test....
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The shift pulse turns off the conducting scs by reverse biasing the cathode gate. The charge stored on the coupling capacitor then triggers the next stage. An excessively long shift pulse charges up all the capacitors, turning off all stages.
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The input signal is amplified by the transistors. The distorted output is then clipped by the two diodes and the high frequency noise is filtered from the circuit via the 500 pF capacitor..
This is the fully featured, jammed packed temperature readout unit. I can measure temperature from up at 8 DS1820 digital temperature sensors all on the same 1-wire bus. That's right only 3 wires are needed to go to all the temperature sensors, GND, VCC and....
I use this power supply for applications that doesn't use too mucho power. It can provide power to circuit that uses less than 100mA without any problem. The disadvantage of this circuit is the danger of an electrical shock, so it cannot be used if the....
The problem with using two zeners back to back in series to get symmetrical clamping is that the knee of the..
This circuit is a simple wire loop alarm that can be used in doorways, hallways, or any other place the tripwire will be broken by intruders. The circuit has a built in siren, but it can be replaced by a relay to drive an external siren, commercial alarm, etc...
This circuit, instead of dividing by an integer, divides the input signal by +1/2. With the feedback connections ..
U1a operates as a low-noise microphone preamp. Its gain is only about 3.9 because the high output impedance of the drain of the FET inside the electret microphone causes U1a?s effective input resistor to be about 12.2K. C2 has a fairly high value in order to....
This GPS receiver is powered by 2 AA batteries. They are only strong enough for the GPS to stay on for about two hours, and this seems like quite a waste. I would like to be able to use a larger battery, and sometimes even an AC adapter...
WinCircuit is a software of realization of drawing of printed circuit in single or double layers. Principal qualities are the facility of use and the sight in pseudo 3D which gets a vision of the circuit close to reality...
This Design Note describes how to generate five separate output voltages using the LTC®1538-AUX, a dual synchronous switching regulator controller with internal circuitry adaptable to many additional configurations...
At this circuit the SSM2044 IC is used, a 4 pole voltage controlled filter designed for electronic music applications. On-chip voltage control of resonance allows direct and easy interfacing with programmers and controllers. The IC features extended control....
Ql and Q2 constitute a simple, high-speed FET input buffer. Ql functions as a source follower, with the Q2 current source load setting the drain-source channel current. The LT1010 buffer provides output drive capability for cables or whatever load is....
The meter reading is directlyjproportiona! to the logarithm of the input light power. The logarithmic circuit behavior arises from the nonlineardiode pnjunction current/voltage relationship..
Antennas that are much shorter than 1/4 wavelength present a very small and highly relative impedance that is dependent on the received frequency. It is difficult to match impedances over a decade of frequency coverage. Instead, input stage Q1 is an FET....
Our present car controller runs on a single PIC16F870 micro and provides functions for remote door locks, headlight reminder, and car finder. It is constructed using wire-wrap to allow for future expansion and is mounted using Velcro on the passenger side....
This metal detector circuit needs to be powered using a 9 volts power supply ( DC) or a 9 volts battery . The C1 capacitor is a variable capacitor with a value of 365 pF , C2 is a 100pF silver mica capacitor , C3 is a 0.05 uF disc capacitor and the C4 is....
This circuit must be connected to a 5 volt DC source. See my RR page for several 5 volt supplies. Note the flashing LED is optional, but looks s-o-o-o-o good on the top of a locomotive...
Inserting two 1-MO resistors, R1 and R2, in the output stage of one of the circuit"s inverters limits the current needed by the oscillator tone more than a few pA. This circuit includes a CD4007 package, which has three CMOS inverters. It forms a standard....
The logic probe can indicate four input states, as follows: floating input—all LEDs off..
The circuit is built around a 741 general-purpose op amp that is configured as a voltage follower; with the components shown, the op amp has a voltage gain of one. The output of the 741 is used to drive a 50- meter movement. Potentiometer R7 is used to zero....
Here is the schematic diagram for a 20 Watt driver. I developed this circuit in 1985, and used it to build a lamp that found much use both as camping light and as emergency light during the then-frequent power outages. The two transistors work as a....
Beeps when hears your whistle A gadget suitable for key-holders, games etc. These devices contained a special purpose IC and therefore were not suited to home construction. The present circuit is designed around a general purpose hex-inverter CMos IC and,....
This circuit is used to trigger a camera`s electronic shutter circuit when a flash of lightning is present. This circuit would also work for photographing fireworks displays or other events involving flashes of light...
Input 1 is used as a gating period, during which a single rising edge on input 2 will cause a logic 1 output-any other number, indicating non-identical frequencies causes a logic 0 output. ICla converts input 1 to a narrow pulse which initializes IC2 which....
A circuit for multiplying the width of incoming pulses by a factor greater or less than unity is simple to build and has the feature that the multiplying factor can be selected by adjusting one potentiometer only. The multiplying factor is determined by....
A preamp designed for the minimalist, and having no frills at all is the design goal for this project. It is designed as a preamp for the Death of Zen (DoZ) Class-A power amp (Project 36), and has very low levels of noise and distortion, in a minimum....
This circuit has read the RIAA equalization, tone controls, and adequate gain to drive most power amplifiers conunercial by using CA3410 op amp BiMOS. Total harmonic distortion, pushed to provide an output of 6-V, is less than 0.035% in audio-frequency range....
The circuit is based on asynchronous decade counter 7490(IC2), a 7 segment display (D1), and a seven segment decoder/driver IC 7446 (IC1).The seven segment display consists of 7 LEDs labelled a through g. By forward biasing different LEDs, we can display the....
This project is intended for controlling mains powered disco lighting, although there are many other possible uses for controlling almost any mains appliance. It will control five seperate channels at up to 3 Amp per channel. This could be increased by....
Using an intersil ICL 7106 A/D converter chip and an LED display module, this gauge uses a Sensym Corp. pressure tra..
The transmitting section of this infrared tx-rx is unusually simple but it works rather well: the infrared LED pulses at a frequency of 160Hz and its range, with its receiver, is between 2 and 4m depending on the transformer used and the setting of the 100k....
The first amplifier circuit is a bird phone. In this circuit, the electret mike (MIC1) is mounted in the neck of a large plastic funnel. The amplifier, built around an MC34119 (which is available from D.C. Electronics, P.O. Box 3203, Scottsdale, AZ....
This circuit uses three easily available 555 timer ICs. All three work as astable multivibrators. The first 555 has an on period and off period equal to 1 sec. This IC controls the on/ off periods of the other 2 555s which are used to flash two bulbs through....
This frequency doubler using a single 4069 hex inverter IC, a frequency doubler can be constructed to give an output pulse train whose frequency is twice that of a squarewave input signal. The signal is applied to the input of N1. It should be a squarewave....
The swept-frequency oscillator offers an inexpensive source of discrete frequencies for use in testing digital circuits. In this configuration, the circuit generates an 80-second seguence of eight frequencies, dwelling for 10 seconds on each frequency. You....
A 0 to 2 MHz ferquency meter with a Minimum Mass Wireless Coupler, based on the ATMega8.Range to the Minimum Mass Base Unit is 10 to 15 cm. Since the frequency meter is battery operated, it can be floated from ground, making life in and around the test bench....
The logic input is applied to opto-isolators Ul and U2 with, respectively, npn and pnp emitter follower outputs. Dc balance is adjusted by potentiometer R2. The emitter followers drive the gates of Ql and Q2, the complementary TMOS pairs. With a ±12 V....
A gas sensor (TGS823 from Allegro Electronics, Cornwall Bridge, CT 06754) conducts in the presence of explosive gases. U5 is a voltage-to- frequency converter that produces a frequency proportional to the sensor conductance. The output frequency ranges from....
An LM317 voltage regulator is configured as a constant-current source. It is used to supply the 50 mA charging current to S01-S06, an array of AA-cell battery holders. Each of the battery holders is wired in series with an LED and its associated shunt....
At this voltage regulator prototype the maximum current, with output shortcircuited it was only 0,5 A, so no overheating occured. In this dc voltage regulator circuit, T1 is for current limitation. As soon as the voltage on the R2+R3 becomes higher than....
These units can be useful as a short-range, single-channel remote-control. When the pushbutton in the transmitter circuit is briefly activated, the LED D1 in the receiver illuminates and an optional beeper or relay can be operated. Circuit operation is based....
This circuitry offers some features that are highly desirable when building a QRP (or ANY) transceiver. It also includes a combination of features that many might not always take the time to include in their projects. Considerable effort has been made to....
Insulated-gate, field-effect transistor (IGFET), Q2 and silicon photo cell Zl form the heart of this circuit. Transformer T1 is an audio-output type, but it"s reversed in the circuit. A sudden flash from a photoflash unit detected by Zl sends a voltage....
If you've crossed the line and play guitar or bass and also sing in a band, you're almost certain to have run into the situation that you step away from the mike to do a solo (or one of those neato, expressive dance steps, or a facial impression of the pain....
This circuit monitors the power-line (ac) voltage. When a power failure occurs, on restoration of power, the circuit a..
A cathode follower based on the 6BL7 or 6BX7 is ideal for output. I used a mu-follower circuit with no feedback, a 12SN7 as the gain stage, and a 6BL7 as the cathode follower/current source. (I have many old GEs I wanted to use, and converting to 6SN7 means....
The object is to get the cell voltage high enough for the sulphate to dissolve without boiling or melting the battery. This is achieved by applying higher voltage for shorter periods and let the battery rest for a while. The pulses on short range is about....
This circuit can be built small enough to frt inside a toy. The circuit consists of a relaxation oscillator utilizing one unijunction transistor (2N2646, MU10, TIS43). R2 and C2 determine the frequency of the tone. Pushing the button, SW1 charges up the....
Integrated circuit Ul (a 555 oscillator/timer) is wired as a conventional pulse generator. The frequency of the pulse generator is controlled by potentiometer Rll. Resistor R2 puts areasonable limit on the highest speed attainable. The output of the pulse....
The positive and negative peak amplitude is controllable to an accuracy of about ± 0.01 V by a dc input. Also, the output frequency and symmetry are easily adjustable. The oscillator consists of an integrator and two comparators—one comparator sets the....
The basic VFC (voltage-to-frequency converter) in Figure 1 comprises an integrator (IC1) and a Schmitt-trigger circuit (IC2). The integrator converts the dc input voltage, VIN, to a linear voltage ramp, and the Schmitt trigger sets the limits of the....
This simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input. It is therefore extremely useful for powering opamp and other circuits that require a dual voltage from a single battery. The circuit will....
Using the software during flight simulation models of planes: REAL-FLIGHT, we first chose a housing of any transmitter empty direct connection potentiometers innings. However this is not good because, first races of the potentiometers are only 90 degrees,....
The very simple circuit uses only two CD4001 packages, i.e., eight NOR gates and operates in the following way: Pulse streams are fed to an RS flip flop generating an output waveform wliich has a small or large duty cycle depending on the direction of....
This project is useful if you wish to experiment with absolute phase, or are just interested in the possibilities of a polarity reversal circuit. In the case of absolute phase, many studies have shown that there can be an audible difference between....
A 6 V battery can provide 100-150 Vdc center-tapped at a high internal impedance (not dangerous though it can inflict an unpleasant jolt). A 6.3 V transformer is connected ' 'in reverse'' with a transistor used in a Hartley oscillator configuration. The....
The telephone-line tester consists of nothing more than a meter (that`s used to measure line voltage in the on- and off-hook state), three resistors (one of which is variable), a pushbutton switch, and a modular telephone connector...
The incoming RGB inputs are terminated with resistors Rl, R2, and R3 and potentiometers RVl, RV2, and RV3. These provide input impedances of approximately 75 0. The presets should be adjusted to provide a maximum input of 1 V pk-pk into the MC1377. The....
A 7 MHz oscillator with a variable crystal oscillator (VXO) operates very stably, but it allows only a small frequency variation (approx. 5 kHz). In contrast, a VFO with an LC resonant circuit can be tuned over a range of several hundred kHz, but its....
The alarm is "set" by opening Sw1. It can be any small 1-amp single-pole change-over switch - but for added security you could use a key-switch. Once Sw1 is opened you have about 10 to 15 seconds to get out of the vehicle and close the door behind you. When....
Because power MOSFETs offer high power gain at both audio and radio frequencies, they are useful in many areas of radio-circuit design. For rf applications, a MOSFET"s large safe operating area, V0 s vs ! 0, protects it against damage from reflected rf....
Pulses from the distributor points are passed through a current limiting resistor, rectified, and clipped at 4 volts. Via Q1 and the diode pump, a dc voltage proportional to engine rpm is presented to RV1; the sharp transfer characteristic of a CMOS gate,....
This self-biasing configuration is useful any time srnall changes in light level must be detected, for example, when monitoring very low flow rates by counting drops of fluid. In this bias method, the photodarlington is de bias stabilized by feedback from....
This is a 8048/IM80C48 Microcomputer with 8 character 16-segment ASCII triplex liquid crystal display. The two bit character address is merged with the data and written to the display driver under the control of the WR line. ..
This high power led mood light is based on PIC16F628 and the ability of this mcu to produce PWM pulses. Varying pulse width we can produce millions of color combinations using only the three basic colors. So only one RGB (Red-Green-Blue) led is capable....
These ultrasonic circuits are all quite old: my notes date them at mid-70s so they don`t use ICs. Nevertheless there are several places where an op-amp would possibly simplify things. Despite their age I hope they are of interest: certainly basic principles....
This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores), or for anything else that may be counted. The circuit accepts any TTL compatible logic signal, and can be expanded easily (see....
The PWM controller uses complementary half-H peripheral drivers SN75603 and SN75604, with totem-pole outputs rated at 40 V and 2.0 A. These drivers effectively place the motor in a full-bridge configuration, which has the ability to provide bidirectional....
This circuit uses the CA3207 sequence driver and CA3208 segment latch-driver in combination to drive display devices of up to 14 segments with up to 14 characters of display. ..
Sounds are picked up by MIC1 and fed to the input of the first op amp. The signal is then fed to the input of second op amp Ulb, where it is boosted again by a factor of between 1 and 33, depending upon the setting of range switch Sl. With the range....
Circuit has a 1 Hz-to-30 MHz output, 150-dB dynamic range, for a 0 to 5 V input. It maintains 0.08% linearity over its entire 71/3 decade range with a full-scale drift of about 20 ppm/°C. To get the additional bandwidth, the fast )FET buffer drives the....
This simple circuit can color the sound coming from your audio system. Clocking for the circuit is provided by an oscillator built from one quarter of a 4093 quad NAND Schmitt trigger. With the component values shown, it will run at about 5 Hz. The....
The most popular LCD interface is the Hitachi 44780 based LCD controller chip which provides a fairly easy to work with interface and low power consumption. The major drawback of the interface is the perceived complexity of working with the interface. This....
This relatively simple, inexpensive circuit requiring one trimming operation can multiply or divide with a consistentaccuracy of greater than 1 part in 1,000. An inexpensive CMOS version of standard 555 timer chip T, in conjunction with low-drift LMll....
Applying voltage to the circuit triggers SCR1. With SCRl on, the voltage on the anode of SCR2 rises until SCR2 triggers to commu-tate SCRl. The voltage on the gate of SCRl will swing negative at this time, and only after a positive potential of 0 volt is....
The Dallas Semiconductor (www.dalsemi.com) DS1722 digital thermometer allows measurement resolution as fine as 0.0625°C in digital form and with linear response. The accuracy specification is only 2°C, but you can improve this figure by careful calibration.....
S/PDIF is an acronym for Sony /Philips Digital Interface (or Sony /Philips Digital Interconnect Format). The full specification for the S/PDIF interface consists of hardware and software, but only the hardware side will be discussed here - the software is....
Driving a D/A converter with an A/D converter provides an overall analog-hold function, which though limited in output resolution, offers zero voltage droop and infinite hold time. The A/D converter shown (IC1) includes a 12-bit compatible track/hold at its....
This is the construction guide for the 5301 wideband fuel mixture display kit. The 5301 is the Tech Edge version (rather than the Jaycar version) of the modified Silicon Chip FMD design, and it features, compared to the original kit, double sided PCBs a new....
This circuit will switch off the line supply to audio or video equipment if there has been no input signal for about 2 seconds. SI provides manual operation and S2 acts as a reset. This circuit allows for time to change a tape or compact disc. ..
This circuit, is basically a resistance ? sensing window switch, except that the ?resistor? takes the form of an NTC thermistor and the circuit thus responds to temperature. TH1 must have a resistance in the range 500ohm - 9Kohm. RV1 is used to set half ?....
The two basic parts for working with IR are the emitter and the detector. The emitter is typically an LED that emits near-infrared light. A typical wavelength is 880nm, which is just beyond the human eyes ability to see. Many suppliers, new and surplus, can....
Many a times one needs an extra telephone ringer in an ad joining room to know if there is an incoming call. For example, if the telephone is installed in the drawing room you may need an extra ringer in the bedroom. All that needs to be done is to connect....
The aim of this design is to reproduce a Combo amplifier of the type very common in the `sixties and the `seventies of the past century. It is well suited as a guitar amplifier but it will do a good job with any kind of electronic musical instrument or....
This amplifier delivers 20 W into an 8-D load using a single IRF520 driving a transformer coupled output stage. This circuit is similar to the audio output stage used in many inexpensive radios and phonographs. ..
This circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. The device formed by Q1, Q2 and related resistors triggers the SCR. Timing is provided by R1, R2 & C1. To change flashing frequency....
Most of the power supply failure indicator circuits need a separate power supply for themselves. But the alarm circuit presented here needs no additional supply source. It employs an electrolytic capacitor to store adequate charge, to feed power to the alarm....
The shift pulse turns off the conducting scs by reverse biasing the cathode gate. The charge stored on the coupling capacitor then triggers the next stage. An excessively long shift pulse charges up all the capacitors, turning off all stages. ..
