The astable multivibrator is a unique form of the relaxation oscillator in which the in-phase feedback is provided by a separate transistor. The first multivibrator was built with vacuum tubes and the circuit was very popular from the start. Millions were built and used in the earliest computers and employed in TV sets in their sweep generation an
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d deflection circuits. Multivibrators generate rectangular waveforms that can also be used for timing generator applications. There is often a need to have a clock oscillator when working with digital logic. Most often complete IC (Integrated Circuit) modules are used or some logic gates for that purpose. Making the clock oscillator from available spare transistors and a handful of surplus parts not usually done because of needless worry of possible circuit complexity. As demonstrated here the circuit is quite simple and it is very easy to customize it for the application at hand. Almost any transistor available is useable in this circuit if the selected frequency for oscillation is not very high. With the values as indicated on the schematic diagram the oscillators frequency is 1 kHz and the cycle time is mSec (mili-Second). With the circuit operating from a 5-volt power supply the output voltage is acceptable to drive TTL and CMOS gates directly. The actual multivibrator oscillator circuit is made up of transistors Q1 and Q2 only for its operation - Figure 1. To be able to obtain the signal from this oscillator without changing its frequency with the external load, transistor Q3 is added as a buffer output amplifier stage. The Q3 transistor isolates the multivibrator and this stage has no voltage gain as it is used for impedance transformation. Transistor Q3 provides low impedance output for the load while presenting high...
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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....
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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....
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....
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