Having trouble getting the LM567 Tone Decoder to work. Referring to the LM567 Data Sheet, thus far I have this. I need to detect a 1.050KHz signal. The detection bandwidth should be approximately 10%.I have an input signal at pin 3 of 282.8mVrms @ 1.050KHz. For the detection bandwidth, I multiplied 1.050KHz by 2200 micro Farads to get 2.31(table 2 of data sheet) which Is close to 10% bandwidth. So for the output filter at pin one I have a 4700 micro Farad capacitor. For the VCO, I have a 5K Ohm pot with two pins connected together(center and one outer pin) connected between pins 5 and 6. Then I have a .33 micro Farad capacitor from pin 6 to ground. I should be able to tune the VCO from 667Hz @ 5K Ohms to 1.3KHz @ 2.5K Ohms. When I tune the VCO pot the frequency at pin 5 on my oscilloscope does not change, in fact it equals the input frequency at pin 3. However, the amplitude at pin 5 does change going from 5.5mV peak down to near zero at the bottom end of the pot. It's about 2.5mV at the center of the pot(approximately 3K Ohms for 1.050KHz). If I shift the input frequency at pin 3, the VCO frequency at pin 5 matches and shifts right along with the input frequency. All this time the output at pin 8 remains high. About the output, I have an LED with a 390 Ohm resistor between pin 8 and the 5 volt supply.The idea is that when the output goes to ground or low, the LED will light.
Hope someone can help...
Thanks...
Thomas...
