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4046

M

merco

Jan 1, 1970
0
hi,
is it possibile to use 4046 as a tone decoder ?
I'd like to use the hook indicator as detector for a 440Hz sine wave
signal...
 
T

Tim Wescott

Jan 1, 1970
0
merco said:
hi,
is it possibile to use 4046 as a tone decoder ?
I'd like to use the hook indicator as detector for a 440Hz sine wave
signal...
A PLL will decode pure tones. To use the 4046 you'll have to square up
the audio into a logic signal. Once you've done that set up the 4046 to
lock on the tone of interest, use the VCO drive as a frequency reading
and (if it's pure enough) the lock pulses to tell you if the tone is
really there.

Having said that, there are probably _much_ better ways of doing this,
particularly since you could probably do some DSP Lite in some little
microprocessor.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
R

René

Jan 1, 1970
0
hi,
is it possibile to use 4046 as a tone decoder ?
I'd like to use the hook indicator as detector for a 440Hz sine wave
signal...

http://www.x-robotics.com/downloads/pdfs/NE567_SE567_2.pdf

Amazed to see it still exists...decades ago I built telex and morse
decoders with it, using the same oscillator in the 567 to generate
telex / morse signals.

(dreams of using the Commodore 64 to decode funny agressive
anti-capitalist Russian propaganda telex...damn - I get old)
 
R

Rick

Jan 1, 1970
0
René said:
http://www.x-robotics.com/downloads/pdfs/NE567_SE567_2.pdf

Amazed to see it still exists...decades ago I built telex and morse
decoders with it, using the same oscillator in the 567 to generate
telex / morse signals.

(dreams of using the Commodore 64 to decode funny agressive
anti-capitalist Russian propaganda telex...damn - I get old)

Heh...my C64 is sitting on the shelf only a few feet away. Used it for the same things and
controlling a DX440 : )
 
K

Ken Smith

Jan 1, 1970
0
hi,
is it possibile to use 4046 as a tone decoder ?
I'd like to use the hook indicator as detector for a 440Hz sine wave
signal...

The XOR phase detector will work with a fair amount of noise. You need to
prevent huge spikes from getting to the PLL chip so there is likely to be
a resistor in the input signal path. You will also need a capacitor in
series to allow the PLL input to self bias.

Vcc
!
--- 1N914
^
! 2.2nF !
--/\/\---+--+-------+-----!!----! Sig in
22K ! ! !
--- ---
1N914 ^ --- 22nF
! !
GND GND


You will want a counter chip so that the VCO output can be made to run at
4 times the 440Hz input. Assuming there is enough noise, you can decode
the "I'm locked" signal with a quad XOR gate chip.
 
K

Ken Smith

Jan 1, 1970
0
A PLL will decode pure tones. To use the 4046 you'll have to square up
the audio into a logic signal.

No, the 4046 will do the squaring up for you. You just need a capacitor
to let is self bias.
 
J

john jardine

Jan 1, 1970
0
René said:
http://www.x-robotics.com/downloads/pdfs/NE567_SE567_2.pdf

Amazed to see it still exists...decades ago I built telex and morse
decoders with it, using the same oscillator in the 567 to generate
telex / morse signals.

(dreams of using the Commodore 64 to decode funny agressive
anti-capitalist Russian propaganda telex...damn - I get old)

Yep!, the same dreams. Used the XR2211 demod chip. Vary, Baud, shift,
damping, centreF. Components calculated on the Sinclair Spectrum then in
turn programmed to do datastream to text. Then add inline audio notch
filtering and amps. Move then onto communications receivers ... Happy days.
Learnt a lot stuff but mainly the niceness of Z80 machine code and the need
for fast, efficient programs.
Won't throw the kit out as there's 6 months of my locked life in it :)
john
 
M

merco

Jan 1, 1970
0
Oh, thanks...
Can you help me qith the design ?
What capacitor ? 220nF ?
 
K

Ken Smith

Jan 1, 1970
0
Oh, thanks...
Can you help me qith the design ?
What capacitor ? 220nF ?

See the ASCII art I did. Look at a 4046's data sheet. Do a bunch of
calculations like:


F = 1 /(2 * PI * R * C) or C = 1 /(2 * PI * R * F)

You'll catch on.


 
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