To anyone who has built one of these, two questions. 1: Did you use the "dead bug" method to mount the I.C.? 2. Do you need a ground plane for it to work?

I built one many many years ago. I don't think dead bug method had been invented yet, but it should work fine. I used a PC board. A ground plane isn't necessary because the frequencies are no higher than about 53kHz.

I used perfbord , no gound plane needed , use hi quality caps , silver mica or polystyrene for the tuned circuits , the beter Q you have the beter and easer it is to tune .

Okay, thanks. What should the range of the variable tuning resistor be? That's enough to get me started.

Which IC are you using? Way back when I built mine, I think I used an LM1800 which has been obsolete for a long time. Looks like the later FM decoder chip TDA1591 is also nearly obsolete.

Are you referring to some specific construction article from somewhere?

I've built several stereo decoders using the LM1800 with great results. The circuit is simple and uses no coils or inductors. Also known as ULN2244. You can buy the NTE-743 replacement for around $10 from a variety of domestic sources. Real LM1800's are sometimes listed on ebay for $5.00. Off-shore warehouses have them cheaper but you have to buy in quantity.

Here's a typical circuit shown driving buffer amps for low-Z output.



Dave

That circuit is similar to one I built and it does work good. For the LED I just used a red 12 volt panel mount LED assembly from Radio Shack which eliminates the need for a dropping resistor. I suspect one could use that pin to drive a transistor and then use the transistor to drive just about any bulb or indicator you want to use.

Here is one using an MC1310P chip. There is a typo, two pin 13 and no pin 3 http://www.circuitstoday.com/stereo-decoder-circuit
Don