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FM modulation with lm567

JimB

Super Moderator
Most Helpful Member
Can someone help me design a FM modulation with lm567.
I assume that you mean an FM Modulator, or, an FM de-modulator.

In either case, the answer is no.
The LM567 has nothing to do with FM, it is a tone decoder.
This means that when it detects a certain frequency at its input (pin3), it will switch state at its output (pin8).

JimB
 

dr pepper

Well-Known Member
Most Helpful Member
No disrespect Jim.
I fiddled aroudn with this circuit a while back trying to put together a synchronous demodualtor.
This guy got a Ne567 to demod Am and Fm, Am isnt brilliant, Fm is more like it, read the blurb:
You might be able to get it to modulate Fm with a varicap, but then the Ne567 max freq doesnt go all that high, only 500kc from memory.
Sorry I odnt have time to do you a design.
 

unclejed613

Well-Known Member
Most Helpful Member
you can use a 567 to demodulate FSK (such as radioteletype) audio. the oscillator's frequency limit is 500khz, so it's not a good choice for modulating or demodulating FM. most FM demodulators work at 10.7Mhz (and depending on the application, on other RF frequencies as well). all of the LM56x PLL devices made in the 1970s and 1980s were generally limited to 1Mhz or less maximum operating frequencies. PLLs can modulate or demodulate FM, but a 567 isn't a good choice.
 

JimB

Super Moderator
Most Helpful Member
This guy got a Ne567 to demod Am and Fm, Am isnt brilliant, Fm is more like it, read the blurb:
Interesting, but given the vast number of ICs available which are dedicated to demodulating FM, this just seems like an exercise in "hey lets see what we can do with this"

PLLs can modulate or demodulate FM, but a 567 isn't a good choice.
Exactly.

JimB
 

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