NJM2211 FSK demodulator problem.

[s3art]

Hi guys,
I tried to build this 1200 baud fsk decoding circuit using this NJM2211 ( the exact circuitary is given in the chip manual -> https://picbasic.com/downloads/NJM2211.pdf) I used the recommand component values fsk decoding too.

I tested the circuit with both a 1.2kHz 1Vpp input and 2.2kHz input, the output at pin 7 was always at 4.x VDC....Shouldn't the output be at "LOW" when my input frequency's at 2.2kHz ?

I wonder why this is happening. Please help =)

* Oh another thing, I set V+ = around +5VDC when i was testing the chip.

 

[Russlk]

Your link did not work for me. Go to this link and click on "data sheet". **broken link removed**

Did you use the values given in table 1, including the trim pot?

 

[s3art]

Yes, I used the values from table 1 and configured that circuit as given in figure 2. I did use a 5K trim pot as Rx.
Though, I'm not sure if I connected the trim pot correctly.

For the trim pot, there was 3 pins and I only used two of them ( I tested these two pins with a multimeter and the resistance was variable ) and i left the third pin open.

i'm sorry for any misused words ...I'm not really familiar with these stuffs.

and ~ Thanks for the help = )

 

[s3art]

Anyone ever used this chip before? Please help.

 

[Roff]

Anyone ever used this chip before? Please help.

I haven't used it, but I noticed that pin 4, according to the pinout on p.1, should be connected to GND. This isn't shown in Fig. 2.

 

[s3art]

HA!..pin4 to GND ....that solved my problem ..
thanks all.