November 10, 2020

Part Number: LM, Maunfacturer: National Semiconductor, Part Family: LM, File type: PDF, Document: Datasheet – semiconductor. The LM and LMC are general purpose tone decod- ers designed to provide a saturated transistor switch to ground when an input signal is present within. DESCRIPTION. The NE/SE tone and frequency decoder is a highly stable phase-locked loop with synchronous AM lock detection and.

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Sign up or log in Sign up using Google. Home Questions Tags Users Unanswered. Rl on pin 8 in the diagram below.

Everything is working OK with the exception of the tone detector, yet I can hear the tone when I hook up a speaker to my circuit at the point where the tone detector can pick the same noise up. It is likely that the lack of output is due to you not having allowed for the fact that the LM has an “open collector” output.

If C3 is too small, frequencies just outside the detection band will switch the output stage on and off at the beat frequency, or the output may pulse on and off during the turn-on transient.

What equation do I use for the input and output filter capacitor for the to successfully detect a 5Khz tone? How exactly does one calculate the proper filter capacitors for the tone detector?


Currently I use 2. I can’t accept this answer because I’m trying to figure out how to calculate values of C3 and C2. Page contains most of what you need to know, but there is also much more there that is useful. Russell McMahon k 9 Without this the device is about as good at detecting tones as is a pillar of salt.

Tone Decoder – National Semiconductor

Lots of ideas – each image links to a page. LM used in IR controller. I think it comes down to the input filter capacitor and output filter capacitor connected to the Output filter capacitor C3 – From Philips data sheet page “The value of C3 is generally non-critical. Such delay may datashert desirable to avoid spurious outputs due to transient frequencies.

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Link to datasheet – for the at least?

LM datasheet, Pinout ,application circuits Tone Decoder – National Semiconductor

Shockingly poor wrt applications. I’m catasheet a wireless remote control system using the and IC’s. The tone I’m trying to detect is a tone at 5Khz. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. C3 sets the band edge of a low-pass filter which attenuates frequencies outside the detection band to eliminate spurious outputs.


National Semiconductor

Sign up using Facebook. The Philips data sheet makes design easy [tm].

Andy aka k 10 What you and other sources online have demonstrated is how to determine the detection frequency using C1 and R1. Email Required, but never shown.

National Semiconductor – datasheet pdf

Output is low when tone is ‘detected’. Sign up using Email and Password. Post as a guest Name. Here is an online calculator for all tone related components. If Datashdet is too large, turn-on and turn-off of the output stage will be delayed until the voltage on C3 passes the threshold voltage.

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. TI LM data sheet here – Detailed design requirements are given in section Natsemi – looks datassheet