LM567 vs LM567CN

[chemelec]

Thsi any use?,

http://www.vk2zay.net/calculators/lm567.php

Is this anything to do with an fm stereo receiver?

NO, It is designed for Touch Tone Decoding on Telephones.

 

[audioguru]

NO, It is designed for Touch Tone Decoding on Telephones.

But the OP said 19kHz which is the FM stereo pilot frequency. Touch-tone frequencies are much lower because a telephone barely produces 3kHz. 19kHz is much too high.
The datasheet has a touch-tone decoder circuit complete with parts values.

 

[chemelec]

But the OP said 19kHz which is the FM stereo pilot frequency. Touch-tone frequencies are much lower because a telephone barely produces 3kHz. 19kHz is much too high.
The datasheet has a touch-tone decoder circuit complete with parts values.

The 567 can operate Up To 500 KHz.

So it can be used for MANY APPLICATIONS.

 

[audioguru]

What is the circuit going to be used for??

 

[Uljabaan]

What Values of Capacitors are you using for C2 and C3 on the 567 chip?

At 440 Hz, C2 should be a 1uF and C3 Should be a 2.2uF Cap.

I was playing the 440Hz sine just to test the Input Voltage, so it's unrelated to the decoder.

 

[Uljabaan]

The volume control of the sound card should affect the signal level. Is the signal taken from the headphone output?
The level 20mV is very low.
Something is wrong. Try to measure the signal level without LM567

I have since changed the soundcard, now the volume does affect the signal level. I am measuring it without the LM567.

 

[Uljabaan]

What is the circuit going to be used for??

Essentially I want to attach LEDs to it and drive them with frequencies >19kHz, encoded in music tracks, something similar to AudioStrobe. But mainly I just want to learn a bit more about electronics.

 

[audioguru]

I am an audio guru but I never heard of AudioStrobe so I looked in Google. I found a BALONEY Instructables article and project about encoding a 19.2kHz signal into the audio stream and using an LM567 in this project to detect it. The article did not say that of course the LM567 will also detect all high frequency audio in the original audio. Then the LM567 drives a few LEDs glued to glasses that you wear and get blinded by the LEDs unless you close your eyes but you can still sense the light.
The light signals are supposed to "entrain" your brain into a trance or something to reduce stress. I think that most people listen to music to reduce stress.

The author of the Intructables project admits that he knows nothing about audio or electronics like most Intructables authors.

 

[Uljabaan]

The detection bandwith can be reduced by choosing bigger C2. With C2=1uF bandwith is about 600Hz.
Recommended C3 > 2×C2
Decoupling capacitor ~ 1uF between 5V-gnd near IC is needed.

Yep, that worked great. I've been experimenting with the C2 value, and with C2 = 220nF and C3 = 460nF the bandwidth is around 1000Hz which is perfect for me.

 

[dr pepper]

Hi chem, it was the freq of 19kc that made me think of fm stereo, 19kc is the pilot tone freq used by receivers to detect the presence of the stereo subcarrier and turn on the decoder.

 

[audioguru]

When I was young and up until my twenties I could hear 19kHz easily and hear ultrasonic "burglar" motion detectors too. The high pitched whistling of this project would drive young people mad and not reduce their stress.