| T O P I C R E V I E W |
| geltara |
Posted - Mar 06 2007 : 7:34:13 PM
what is the use of the transistor or its main function? and then i dont know the flow of the circuit.... kindly explain pls.... im in the philippines right now i cant identify the line of the phone.... |
| 5 L A T E S T R E P L I E S (Newest First) |
| audioguru |
Posted - Mar 09 2007 : 7:14:29 PM
quote:
Originally posted by geltara
hey how can we know it is running? does the led lights when it is attach on the line or when your making a call? when well it light?
The phone bug circuit is connected in series with the phone. When the phone is not being used then the bug and the phone do not draw current so they don't work.
When you use the phone it and the bug draw current and the LED lights up. |
| geltara |
Posted - Mar 09 2007 : 5:01:37 PM
hey how can we know it is running? does the led lights when it is attach on the line or when your making a call? when well it light? |
| audioguru |
Posted - Mar 07 2007 : 09:10:48 AM
You need to learn about electronics basics (inductors, diodes) before you understand how an FM radio transmitter works. |
| geltara |
Posted - Mar 07 2007 : 01:42:00 AM
what about the inductor besides the transistor, what is its function? the placement of the diode also... |
| audioguru |
Posted - Mar 06 2007 : 8:28:12 PM
The transistor in The FM Bug project is a Colpits Oscillator (look it up in Google) that oscillates at about 100MHz. Audio signals on the phone line change its operating voltage. When its operating voltage is changed then the capacitance of the transistor is changed. When the capacitance of the transistor changes then its frequency changes which produces FM.
The circuit is too simple to work properly. If anything gets near it then its frequency changes. It doesn't have treble boost so it will sound like it has no treble audio frequencies when it is heard on an FM radio. |
