Quote:
Originally Posted by baza100
Hello it works in a fashion. I only get it to play through the radio when I am touching the round thing i have marked in the picture with the pen. Any ideas? When I touch the wire where the aerial is there is nothing at all. Thanks Barry
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The component pointed at is Q1. Sounds like you're close but not there yet. You need a yard/meter of so of wire from the non-earthed junction of C13 and the secondary of L2 - the side where there are three pins but the centre one isn't connected to anything.
When you turn the centre ferrite slug of L2 (just use a flattened cocktail stick as it will break with anything metallic) the signal should increase in volume in the radio. If not there is something wrong around Q2 and associated components. Obvious question, but is Q2 in the right way?
What voltage readings have you made? The RF might affect your meter, but assuming you're using a 9V battery, you should be getting something like this:
Q2C 4V
Q2B 0V
Q2E 0V
IC1 pin 5, 4.5V
If you're getting some modulated signal I expect you have correct voltages around Q1 and the IC.
L1 sets the frequency and L2 matches the output transistor to that frequency. If they are not both tuned to the same frequency you'll get hardly any output.
I find it hard to get my head around Veroboard layouts, that's why I use any of the other construction methods previously mentioned in this thread. Check again that all the tracks you think are cut really are, with no shavings shorted to adjacent tracks.
Let us know how you get on.
Ian