Little help guys?

[bigbassman]

I decided to have a go at this,to pass some time http://2manytoyz.com/COL.html I followed it to the letter with some help from member 'cookieraider' who had a couple resistors to spare (cheers Clive).Trouble is,the LED comes on,but not at the right time.It stays off while a signal is present,but comes on for a few seconds immediately after the scanner begins to scan again.I used a PRO-2006 for the project and didn't have any problems construction wise.What could be the problem?

[Mattylad]

I might be wrong here, but to me it looks like the LED should be reversed, a positive voltage on the 10k makes the transistor turn on and connect the circuit above it to ground.
So the voltage above the transistor and thus above the LED would be positive\+v and hence the LED should have the anode at the positive side and the cathode closer to the resistor.

What you are seeing is the led being illuminated when the transistor is off.

Try turning it around.

[bigbassman]

OK Matty I'll check that out.Sounds reasonable.Thanx for your input.

[Mattylad]

Let us know if it works then and we can contact the site above and tell him of his mistake.

[bigbassman]

OK guys.Heads up.I swapped the LED connections but this had the effect of stopping the blue light coming on at all.So I put them back the way they were and the same effect returned.No blue light during transmission,but coming on for about 2 seconds after transmission ends.Guess I'll need to start from scratch again and make sure the transistor legs are connected properly etc.Wish me luck.

[bigbassman]

Nope.Took it apart again and all is fine as per the pictures.Its as if the LED is being switched on at the wrong time,and as the only 'switch' involved is the transistor,could it be wired wrong? Or am I barking up the wrong tree.The guy shows his rigs all working OK and if he wired them like the one in the pics then I'm doing something wrong,right?

[bigbassman]

OK.When the guy said to solder a wire to pin 4 of the 10420 chip and I soldered it to pin 3,does that make me a bad person?? No! It doesn't. I swear,if I had brains I'd be dangerous.Sorry to have wasted your time Mattylad.All is fine.Working great.

[Mattylad]

And it works like that - with the LED the wrong way around?

Weird...

Glad it working though, not to worry about the numpty mistake - we all make them.

[bigbassman]

Seems so mate.Although I thought myself that an LED would only work when connected the right way round,it being a diode and all.The pin on the chip that I originally connected it to was the audio mute pin,as opposed to the (correct)scan control. Hey-ho!