Am transmitter : QUARRIES IN INDUCTOR.

i HAVE GOT THE AM TRANSMITTER CIRCUIT FROM INTERNET... . Intialy i am facing the problem of making the inductor ..i have rolled the inductor coil across the plastic hollow cylinder... plz tell me about the possible errors and what about the others problems that AM transmitter come across.. THE CIRCUIT THAT I HAVE USED ITS LINK IS BELOW...

AM Transmitter Circuit

Problems you may face:

1. It isn't temperature stabilized so expect some frequency drift as it warms or cools.
2. It isn't voltage stabilized, frequency will drift as the battery discharges.
3. The proximity of items near to the antenna will shift it's frequency.
4. Both sides of the tuning capacitor are 'live', expect the frequency to shift as you touch the control as well as turn it.
5. The modulation control is poorly wired and will only have limited range.
6. For most electret microphones (a true condenser mic would not work in this circuit) the value of R9 is too low, a value between 4.7K and 10K would be more appropriate.
7. Some of the other values are not optimal.

Having said all that, it might work. If it doesn't, try connecting a capacitor of 10nF from the top of C3/L1 to ground.

Brian.

If its the first circuit that the link points at, its a medium wave circuit and the text says get the coil out of an old AM receiver. As its value on the circuit is 200 microH, you need, say 50 turns on a ferrite rod (to increase its inductance). Are you anywhere near this?
Frank