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This datasheet has been download from: Datasheets for electronics components. LM datasheet, LM circuit, LM data sheet: NSC – LMC Voltage Controlled Oscillator,alldatasheet, datasheet, Datasheet search site for Electronic. LM National Semiconductor datasheet pdf data sheet FREE Datasheets (data sheet) search for integrated circuits (ic), semiconductors and other electronic.

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You should provide a schematic of your test setup.

pll – LM Frequency deviation problem – Electrical Engineering Stack Exchange

Use the values shown to get a general idea, and if the capacitance is doubled then frequency is halved and vice versa of course. However, the supply voltage must be regulated, or the amplitude of the datasueet outputs will vary with the supply voltage. The circuits aren’t critical, but I do recommend that you use a nF ceramic capacitor as close as possible to the IC supply fatasheet. It’s not a perfect sinewave by any means, but it’s quite acceptable for frequency response scans.

The circuit relies on feedback, and even a seemingly trivial error will stop it from working. A positive modulation voltage causes the frequency to increase, and vice versa. If these aren’t high on your list of features then much simpler VCOs are easily constructed using a timer or similar.

By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. R6 and R7 set the threshold, which is also affected by the output voltage from U1B. Because most are unable to pull the output voltage down to the negative supply, we need to add an extra resistor R9, Figure 3 to ensure that the transistor Q1 will turn on and off properly.


How does the circuit work?

In such oscillators, an LC tank circuit is used for producing oscillations. Therefore, the maximum frequency is Hz, and the minimum is Hz.

Sign up datwsheet Email and Password. Message 7 of 7. This isn’t needed for the LM, but is required for many other opamps that are a great deal faster. The output frequency of the VCO datwsheet be obtained using the following equation: If Q1’s emitter is connected to ground commonly seen in schematics on the Net, but not recommendedthe base-emitter junction can be reverse biased to the point of possible breakdown.

Sign up using Facebook. This is engineering, not poetry. Previous post Next post. The output level and distortion will change with temperature.

LM Datasheet National Semiconductor pdf data sheet FREE from

Voltage controlled datasheey can be broadly classified into a linear voltage controlled oscillators and relaxation type voltage controlled oscillators. The output frequency vs. The lk566 modulation is clearly visible, as is the wave shape. Better performance may be available from a TL or any other reasonably fast opamp.

Many function generator ICs use an expanded version of the diode clipper to get better distortion but with a far more complex circuitbut it’s rarely much better than 0. Don’t be afraid to use enough words to explain your problem unambiguously.

It will work with as little as 50mV input, but will become lk566 non-linear and somewhat unpredictable. Unfortunately, the NE or LM which was an equivalent is no longer available from any reputable supplier. The maximum frequency is also limited, so these circuits can’t be used for RF applications.

This depends on what level of accuracy you need. The only thing you can do is to check all wiring very carefully, secure in the knowledge that if everything is wired exactly as shown, it will work.


The block diagram of a typical voltage controlled oscillator is shown below. Voltage controlled oscillator is a type of oscillator where the frequency of the output oscillations can be varied by varying the amplitude of an input voltage signal.

While the LM is quite ok for a fairly basic VCO, it doesn’t scale well to higher frequencies above 5kHz or so because it’s a low power opamp with very basic specifications. The frequency changes on its own accord. The output frequency can be also programmed using a set of external resistor and capacitor.

(PDF) LM566 Datasheet download

For many applications, and especially for running frequency scans on speakers or crossover networks or any filters for that matteryou usually need at least a reasonable approximation of a sinewave.

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. As shown, four diodes are used to clip datasbeet triangle wave in such a way as to get minimum distortion.

The modulation input will cause the frequency to change by a factor that is directly related to the input level. Sensitivity is halved because the effective supply voltage has been doubled compared to the single supply version shown in Figure 2.

You’ll find countless examples of this circuit on the Net, but since you will be unable to get a reliable source of the ICs it’s a moot point. An opamp VCO circuit is shown in the LM opamp datasheet, and that’s the basis for the design shown here.

Relaxation-type voltage controlled oscillators are used to produce a sawtooth or triangular waveform. It’s actually a clever design, and relies on U1A to integrate the source modulating voltage to produce a positive-going linear ramp.