Simple Fm Radio

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mgazza
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Posts: 3
Joined: Sun Aug 28, 2005 7:43 pm

Simple Fm Radio

Post by mgazza »

hi, im a noob to radio stuff. iv built a small fm radio but cant seam to recive it. im using a 555 in astable mode to create a continuious tone(r1=1k c=1uf)(pins 7 and 6 joined) and then a simple LC loop with a 30pf trimmer and 0.1uh air coil i can here the 555 tone on AM at about 230khz(LW) but i get nothing on fm 86-108mhz.

from the 555 pin 3 the circuit is
555_____R1__________________ANT
########|#######|#######|
########|#######L1######C1
########R2######|_______|
########\b#####c/#######|
##########(NPN)#########C2
################e\______|
#################|
#################R3
#################|
#################GND
R1= 4.7k
R2= 4.7k
R3= 15k
C1= 35pf trimmer ( -|/(- )
C2= 25pf ( -||- )
L1= 6 turns 22 gauge wire (0.1uh) air core

any ideas :)

hope u can understand the diagram lol!

regards mark
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