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Latest Projects Education. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Tone Decoder LM not working. Thread starter prkandel Start date Sep 3, Search Forums New Posts. Thread Starter prkandel Joined Sep 3, 8. I bought an IC named LM from the market and wanted to use this an a bandpass filter which would give a low output when the input signal to it was 40kHz.

In all other conditions and no input signal condition, as per the datasheet states, the output at pin 8 should be a high. But while connecting the circuit as per the datasheet, the output pin 8 does not give a logic high while there is no input to it.

Should not it give a high output as soon as the IC gets the supply Vcc and there is no input to it? And one more question is that how much input voltage can I give to this IC? So does this mean that the input can be a mV signal riding on Vcc? Waiting for replies. Thanks in advance. Scroll to continue with content. Hello, Do you have a schematic you can post here? Hello, The output of the LM at pin 8 is open collector: You will need a resistor from the pin 8 to the powersupply to see level changes.

Try a 4K7 resistor for a start. The given diagram can be found on page 8 of the attached datasheet. Okay, I will try this tomorrow. But can't I just measure the output from Pin 8 with respect to ground and know whether the output is high or low?

I had read that the output of the decoder is low when the input signal is of the same frequency as the internal oscillator, which indeed is controlled by the resistor between pin 5 and 6 and the capacitor at pin 6. In other situations including when there's no signal, the output should have been high.

However, for me, the output is not high when there is no input. AnalogKid Joined Aug 1, 8, You are assuming that any output pin can swing both high and low, and this is not correct. Some output pins do not have the ability to produce a positive output voltage.

In this case, you complete the output circuit by adding a resistor from the output pin to the positive power supply at pin 4. Hello, What values do you use for the timing resistor and capacitor? AnalogKid said:. View attachment Bertus. GopherT Joined Nov 23, 8, I will try this too.

Well then, if I add a resistor from output pin to power supply, the output at no input will probably be high. Will this also make sure that the output at required frequency be low? Last edited: Sep 4, GopherT said:. The datasheet is your friend. Yes, to your question. View attachment Should be ok. Max input on pin 3 is 5. You must log in or register to reply here. You May Also Like. Continue to site. General Electronics Chat.

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LM567 NE567 Tone Decoder

Condition: New product. Expected Availability Date:. By buying this product you can collect up to 2 loyalty points. The minimum purchase order quantity for the product is 1. Add to cart. Add to wishlist. The LM are general purpose tone kHz decoders designed to provide a saturated transistor switch to ground when an input signal is present within the passband.


National Semiconductor

In this lab we will experiment with the tone decoder chip LM In the block diagram, the phase locked loop includes the upper phase detector and the current controlled oscillator rather than a voltage controlled oscillator. C2 provides loop filtering. The lower phase detector produces a signal with a DC level that is filtered by C3 and detected by the comparator to produce an output. The output of the comparator is a open collector and needs a pull up resistor. There are several different data sheets for this chip. The National Semiconductor data sheet is brief and does not have as much information as that from Philips Semiconductor.


LM567 Decoder. Datasheet pdf. Equivalent

The post discuses the main specifications, datasheet and working principle of the IC LM, which is a precise phase-locked loop with synchronous AM lock detection and power output device. Needless to say this chip can be used for a number of different applications, the most common being in the field of remote controls, and security systems. Referring to the the above shown IC LM internal configuration diagram, the pinout function of the IC may be understood from the following points:. Pin 3 is the sensing input of the input, which is used for detecting a given phase-locked loop frequency, in other words this pin will lock-on with the matching center frequency which may be set inside the IC through a pair of external RC network. The Pin 5 and 6 are used for creating the center frequency by setting up the values of R1, C1 as required, and this frequency is used by the sensing input pin 3 to lock-in and create a logic zero at pin 8 which is the output pin of the IC. Output Pin 8 is normally logic high and becomes logic zero as soon as a matching frequency is detected at pin 3 of the IC. Pin 1 and pin 2 are used for ensuring proper filtration of the involved frequencies so that the IC does not create any false output due to any existing spurious or stray noise interferences.


LM567 IC - Tone Decoder IC


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