Step 8: =====PDF File=====

emran16122 years ago
why Audio + is also connected to GND? pls help bro.
jsawatzki4 years ago
Hi man whats up great instructable.
am trying to build based on your circuit schematics but am having some problems:
1. I read on the comments that i shouldnt use a linear taper potentiometer from radio shack so i need to change mine.
2. the Vin ur using is 5 volts, the timer i bought is a 555cn timer ic from radio shack but it says 18v max 4.5-16v type that means it will handle from +4.5 to +16v and from -4.5v to -16 volts right? and since am using a 9 volt battery for the input i should need to worry about using a voltage divider to bring the voltage down to 5 volts right?
3.bow how do u connect thenpn transistor, the emitter goes to the antenna, the base goes to output or #3 on timer and collector goes between R2 and threshold or #6 on the timer.
4. and last this is the most stupidiest question, haha, he phone jack will be conected to my radio in port right? and if dats the case then the part of the npn transistor that is hooked up to the antenna is the collector, right?
thanks a lot man!

jensenr30 (author)  jsawatzki4 years ago
  1. Linear is better for this project.
  2. When the 555 packaging says "4-16v", it means that as long as pin 1 is connected to ground (0 volts), pin eight may be connected to any voltage between 4 and 16 volts. If you have a 9v battery, connect the positive terminal (+9v) to pin 8 and connect the negative terminal (0v or ground) to pin 1. This will be well inside your alloted voltage range.
  3. the base of the NPN transistor is connected to pin 3 (preferable through a 1 Kohm resistor). the collector is connected to the positive terminal of the 9v battery. And, finally, the emitter is connected to the piece of wire that is your antenna.
  4. Audio + is connected to pin four. Audio + is also connected to GND through a 10,000 pf capacitor. On the other hand, Audio - is connected only to GND.
I hope this answers all of your questions. If it doesn't or if you have any more, just ask!
Be sure to check out my other inst'ables!