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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By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. 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 lm57 point where the tone detector can pick the same noise up. I think it comes down to the input filter capacitor and output filter capacitor connected to the Currently I use 2.

National Semiconductor – datasheet pdf

What equation do I use for the input and output filter capacitor for the to successfully detect a 5Khz tone? 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.


Rl on pin 8 in the diagram below. Datasjeet is low when tone is ‘detected’.

Without this the device is about as good at detecting tones as is a pillar ratasheet salt. Page contains most of what you need to know, but there is also much more there that is useful.

Output filter capacitor C3 – From Philips data sheet page “The value of C3 is generally non-critical.

C3 sets the band edge of a low-pass filter which attenuates frequencies outside the detection band to eliminate spurious outputs. If C3 is too small, frequencies just outside the detection band will switch datasheey output stage on and off at the beat frequency, or the output may pulse on and off during the turn-on transient.

If C3 is too large, turn-on and turn-off of the output stage will be delayed until the voltage on C3 passes the threshold voltage.

Such delay may be desirable to avoid spurious outputs due to transient frequencies. TI LM data sheet here – Detailed design requirements are given in section Shockingly poor wrt applications.

Natsemi – looks familiar: Here is an online calculator for all tone related components.

LM567 Datasheet PDF

Lots of ideas – each image links to a page. LM used in IR controller. 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.


Home Questions Tags Users Unanswered. How exactly does one calculate the proper filter capacitors for the tone detector?

Tone Decoder – National Semiconductor

I’m making a wireless remote control system using the and IC’s. The tone I’m trying to detect is a tone at 5Khz. Link to datasheet – for the at least? The Philips data sheet datazheet design easy [tm].

Russell McMahon k 9 Andy aka k 10 I can’t accept this answer because I’m trying to figure out how to calculate values of C3 and C2. What you and other sources online have demonstrated is how to determine the detection frequency using C1 and R1. Sign up or log in Sign up using Google.

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Post as a guest Name. Email Required, but never shown. Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your datasbeet use of the website is subject to these policies.