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8051 / 8052
PCB CAD Software
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555 Timer Circuits
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H Bridge Circuit
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Digital Signal Integrity
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4 Band Resistor
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Astable Oscillator Circuits
Astable Oscillator Circuits
Low Cost Pulse Generator circuit
This pulse generator produces square pulses from 1Hz to 100KHz with adjustable pulse width of nearly 0-100%. The generator is powered with a voltage of 5-15V and is therefore suitable for both TTL and CMOS circuits. If you want to measure the response of an amplifier or give timing pulses to a variable frequency digital circuit or drive a pulse...
Before power is applied, the input and output are at ground potential and capacitor C is discharged. On power-on, the output goes high (Vdd) and C charges through R until V is reached; the output then goes low (Vss). C is now discharged through R until Vn is reached. The output then goes high and charges C towards VP through R. Thus input A...
Dual astable multivibrator
This dual astable multivibrator provides versatility not available with single timer circuits. The duty cycle can be adjusted from 5% to 95%. The two outputs provide two phase clock signals often required in digital systems
The 4047 is configured as a free-running, astable- multivibrator (oscillator) circuit. That configuration, offers three different outputs. The output pulses at the Q and Q output (pins 10 and 11, respectively) are the same as in the previous two circuits. The third output at pin 13 pulses twice as often as the outputs at 10 and 11. So, the...
Uses CA3130 BiMOS op amp that operates at a frequency of 1 kHz. With rail-to-rail output swing, frequency is independent of supply voltage, device, and temperature.
This astable will trigger itself and run free as a multivibrator. The external capacitor charges through RA and RB and discharges through R8 only. Thus, the duty cycle is set by the ratio of these two resistors, and the capacitor charges and discharges between 1/3 Vs and 2/3 Vs.
The power bandwidth of the HA-5147 extends the circuit"s frequency range to approximately 500 kHz. R, can be made adjustable to vary the frequency ifdesired. Any timing errors because of Vas or hu., have been minimized by the precision characteristics of the HA-5147. Dl and D2, if used, should be matched to prevent additional timing...
Nearly half duty cycle multlvibrator
Three factors contribute to the output symmetry. The capacitor charges and discharges through the same external resistor. An internal resistive divider sets accurate switching thresholds within the chip, the bipolar types use dividers, as well. Most importantly, ICl"s CMOS output stage switches fully between ground and ICc, avoiding the...
Double astable multivibrator circuit diagram
As shown, the circuit consists of a dual time base circuit 556 consisting of two synchronized multivibrator, two output clock
555 Timer astable oscillator circuit
555 timer circuit unsteady open and closing times are independent of each other. Wherein a time constant is 1.1RcC2, another time constant is 1.1RcC3. Free-running period is th
555 astable multivibrator circuit diagram
As illustrated, the 555 (or 556 1/2) and three resistive, capacitive element connected as shown, constitute astable multivibrator mode. And one-shot mode except that only the t
Three astable circuit diagram
As shown for the three astable circuit. From this circuit can be seen, each level of the base of the transistor by a capacitor connected between the two levels are tightly coup
Astable multivibrator using too many electronic devices, widely used in the pulse signal generating circuit, which works as 17-18 in FIG. From the figure shows, with A coupling
Telephone Ring Modulator
The circuit requires four astable multivibrators for its working. Therefore two 556 ICs are used here. The IC 556 contains two timers (similar to 555 ICs) in a single package. One can also assemble this circuit using four separate 555 ICs. The first multivibrator produces a rectangular waveform with 1-second low duration and 2-second high...
High Speed Logic Astable Multivibrator (MC74HC04)
The MC74HC04 IC is a low cost CMOS Hex Inverter. I used this type mainly because, it is what I have, although you can use LS type but, with a little modification or exemptions..
Water Activated Alarm
The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. As the probes get wet, a small current flows between base and emitter and the transistor switches on. A larger current flows in the collector circuit...
Transistor tester fits into your pocket
It can be helpful to rapidly and easily determine the polarity (npn or pnp) and function of a transistor. The pocket-transistor tester in Figure 1 is ideal for quickly testing without regard to such parameters as gain and frequency response. You connect the transistor, or device under test, between the collectors, T, of an astable multivibrator....
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 reputable time signal (GPS, WWV/H, or Telstra 1194 on a fixed landline telephone). The box...
LED driver delivers constant luminosity
The circuit in Figure 1 is similar in principle to that of a previous Design Idea (Reference 1) but offers improved, more reproducible performance. The output current is almost constant over an input-voltage range of 1.2 to 1.5V and is insensitive to variations of transistor gain. Transistors Q1 and Q2 form an astable flip-flop. R1 and C define...
The LED Torch is based on a 7555 timer running in astable mode (do not use an ordinary 555). A white LED (Maplin order code NR73) produces 400 mcd light output, which, when focussed, can illuminate objects at 30 metres. Try Conrad Electronic for what appears to be a stronger white LED (order code 15 37 45-11). A convex lens with short focal...
Electromechanical door chimes can enhance your home, but they are vulnerable to costly repair problems. A defective pushbutton switch or a careless visitor can maintain the chime in an energized state for a prolonged period, thereby damaging the chime. The circuit in Figure 1 prevents damage to the chime and improves the chime`s effectiveness by...
10Hz - 100KHz Function Generator with AT90S1200
The presented project is a function generator for sinusoidal and square signals production. The output frequency covers the range from 10 Hz to 100 KHz with a step of 2 Hz. The waveform synthesis is based on the D.D.S. technique (Direct Digital Synthesis) and the output frequency is selected through a microcomputer with an embedded thumb...
Picured in Figure 1 is a miniature magnetic gun. When optimally tuned, it will propel a small slug about 1.5 metres high, or 2.5 metres horizontally. IC1 is a 555 timer in astable mode, sending approx. 10 ms pulses to decade counter IC2. IC2 is continually reset through R3, until pin 15 is taken low through the "Fire" button. IC2 then...
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 do not modify R1 and R2 values: set C1 value from 100 to 2200µF instead.
Recalibration Utility Oscillator
The PIC 12F629 and 12F675 devices have an internal 4Mhz oscillator that enables the devices to be used without an external crystal or RC network. This frees up one or two pins for I/O use and allows the device to be built into minimum component count designs. The internal oscillator needs to be calibrated and this is achieved by reading a...
Astable Timer with PIC 12F629 / 12F675
This software functions as a long period astable mutivibrator. The mark and space period can be set from 1 second up to a maximum 65535 seconds (18h12m15s). Using the internal 4Mhz RC oscillator delays with an accuracy of 99% or better can be achieved The code also implements an edge triggered reset and an active low hold function. The...
The use of positive feedback is useful for producing oscillators. The condition for positive feedback is that a portion of the output is combined in phase with the input. For an amplifer with positive feedback the gain is given by the expression below.
Mosquito repelant circuit
The Astable Multivibrator, which is generally used as a signal generator, is once again used here to generate the desired frequencies. It is an excellent example of the fact, how versatile simple basic electronic circuit can be. It seems quite obvious then, that by creating these insects frequencies electronically, we should be able to repel...
0 to 9 asynchronous decade counter 7490 display
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 digits 0 through 9.
Astable Multivibrator with 2 Transistors
This circuit is basically simple and easy to build, it uses two transistors as active components and a few passive components like resistors, capacitors and two LEDs. The circuit makes use of the MPS2222 transistor. You can use any NPN type transistor as the basis of your circuit provided that, the transistors Emitter-Base Voltage is less...
Maxim's MAX038 function generator chip is capable of producing nearly constant amplitude sine, square, and triangle waves with a low output impedance, from a very low frequency to more than 20 MHz. Basically, a function generator on a chip. Here is a function/sweep generator that uses the MAX038 chip. The design described on these pages are not...
Chua's Oscillator circuit
The applet shows a simulation of Chua's circuit, plotting the voltage measured across C1 against the voltage measured across C2. This corresponds to the display on an X-Y oscilloscope with probes connected across these capacitors. The initial values of the parameters used in the applet correspond to the component values in the circuit diagram,...
Colpitts Oscillator Circuits
Crystal Oscillator Circuits
Hartley Oscillator Circuits
RF Oscillator Circuits
Sine Wave Oscillator Circuits
Square Wave Oscillator Circuits
Volt Controlled Oscillator Circuits
Wein Bridge Oscillator Circuits
Pierce Oscillator Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial