Astable

Astable multivibrator with two LED

This is one of the basic circuitry of the electronics. The multivibrator astabiele shows two LEDs alternately light up with an adjustable speed. The circuit uses two transistors conduct alternately by the capacitors charged and discharged. The rate at which this happens depends on the capacity of capacitors of R2 and R3 and P1, and the load of the transistors...

Astable multivibrator circuits

What exactly is a multivibrator? I suppose one definition would be 'a circuit which has several states'. This will do for now, it's quite loose so leaves plenty to the imagination! Conventional multivibrators have only two stages and come in three flavours: astable (where neither state is stable and the circuit oscillates between the two states); monostable (where one state is stable, the other transient). And bistable, where the circuit can be flipped from state one to state two. The fact that it can be 'flopped' back again leads to another term 'flip-flop' - but you can call an astable an astable flip-flop! Then you can get tristables - and one circuit I shall introduce is a 'donkey simulator' where 3 transistors are combined to make 3 separate astable mulivibrators!..

Variable astable frequency oscillator

This is a very simple circuit utilising a 555 timer IC to generate square wave of frequency that can be adjusted by a potentiometer. With values given the frequency can be adjusted from a few Hz to several Khz. To get very low frequencies replace the 0.01uF capacitor with a higher value. The formula to calculate the frequency is given by: 1/f = 0.69 * C * ( R1 + 2*R2) ..

Morse Code astable Oscillator

Astable or free-running multivibrators have been used in home-built amateur radio equipment for many years. The basic circuit is a two stage amplifier with AC-coupled feedback from output to input. One transistor stage is on ( conducting current ) while the other is off ( not conducting current ) until the stages switch conducting states repeatedly at a specific frequency. The oscillation frequency is set by the resistor and capacitor values connected to the base terminal of each stage. This RC network determines how long the transistor stays in the off position. Presented are two projects which utilize astable multivibrators built using the ubiquitous 2N3904 BJT. The first project is a code practice audio-frequency oscillator while the second is a simple , no-frills electronic keyer for keying a transmitter. Either circuit would be a great first project to learn how to build circuits using Ugly Construction...

Function Oscillator using 8083

Built around a single 8038 waveform generator IC, this circuit produces sine, square or triangle waves from 20Hz to 200kHz in four switched ranges. There are both high and low level outputs which may be adjusted with the level control. This project makes a useful addition to any hobbyists workbench as well. The waveform generation is produced by IC1. This versatile IC even has a sweep input, but is not used in this circuit. The IC contains an internal squarewave oscillator, the frequency of which is controlled by timing capacitors C1 - C4 and the 10k potentiometer. The tolerance of the capacitors should be 10% or better for stability. ..

Function Oscillator Generator (MAX038)

Oscillation frequency 10Hz ~ 20MHz, 6 ranges. Analog output Sine, triangle, square wave (0 ~ 4Vp-p, Zo = 50?). TTL Output Clock (Duty: 50% fixed) positive negative pulse (variable pulse width). Operating system Show: oscillation frequency and operating mode LCD display. Operation: Operation mode switching and analog volume adjustment. Power AC 100V. Production cost \ 10,000 or less. The circuit diagram has not been specified, as small as possible to process and put the power supply impedance bypass capacitor is not appropriate to say. Well, around here is a basic high-speed circuits. LM6361 analog output buffer is used. This amp I have GBW = 50MHz bandwidth, this is a little short. AV = +6 dB, so that you are using in, 20MHz in the vicinity would become almost a sine wave to square wave output is selected. More bandwidth (200MHz degree) you may want to use a buffer amplifier...

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, and show a simple periodic orbit (oscillation). The transition to chaotic dynamics can be found by carefully decreasing R or C1, (e.g. decrease R in steps of 0.01 to 1.2K). The simulation compares well with what is actually seen on an oscilloscope. Chaos seems to develop via a subharmonic cascade...

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 these insects! The most important point to remember here is that, unfortunately, this method has so far not been completely sucessfull. Whereas one group of insects can be made to run away at frequencies around 5 KHz, other types may desert only at higher frequencies, about 10 to 20 KHz. For some types, all the frequencies may fall on deaf ears! Yet other theories propose that in fact some frequencies may even attract them instead of repelling. ..

Sweep/Function Generator

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 so much instructions for duplicating the design as they are a collection of ideas to stimulate your own thoughts. The symmetry of the waveform, or duty cycle in the case of the square wave output, is variable. The performance of the generator is highly dependent upon physical layout. There is one frequency marker circuit and two selectable controls. This, in conjunction with the ability to switch the oscillator's frequency control to the selected marker pot allows accurate setting or location of the frequency marker...

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....

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 than 12V and has a maximum value of 5V...

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...

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 wheel keyboard...

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 then keeps bleeping, can be taken to an observation site, and can be used there for an hour or so, before the time slowly drifts too far out of calibration...

The circuit has both square-wave and triangle-wave output. The left section is similar in function to a comparator circuit that uses positive feedback for hysteresis. The inverting input is biased at one-half the Vcc voltage by resistor R4 and R5. The output is fed back to the non-inverting input of the first stage to control the frequency. ..