So I tried to build this radio transmitter
http://www.uoguelph.ca/~antoon/circ/fmt1.htm
However when I try to pick up the signal right out side on my car radio. (or any radio for that matter)
It doesn't work. I have check the connections they all look good.
The only thing I was having problems was with which leg for the 2N3904
NPN transistors was the emitter and collector. I see a small line on top of the transistors I am wondering is this the collector or emitter leg? I am assuming with these transistor the base is the middle as the picture on the back of the package shows.
Also I am using radioshacks part 270-0090 Condensor microphone.
It has one leg that has 3 green lines is this the leg that goes to ground or power side? ( think I tried both )
For the antenna I used around 8 to 12 inchs of 22 gage magnetic wire.
For the inductor I used 10-11 coils around a pencil. I left the pencil in the middle of the inductor coil should I take it out or does it not matter if it's their? I used 22 gage magnetic wire for the inductor as well.
For the capacitors I used 0.01uF and 0.1uF polyester-film capacitors
For the resistor I used 1/8 watt carbon-Film resistors radioshack 271-003 500 pack. This had all the size resistors I need in it. I don't think I need more the 1/8 watt power?
I used a 9volt battery.
The only thing I didn't have is the varible capacitor and the 4.7 pF capacitor. They just didn't have these. But I have alot of 1, 10 , 15 pF cermic capacitors I just but them in parrell to make desired capacitor variations for the varible capacitor. I think I should still be able to get something.
For the 4.7pF I just used 5 1pf or 4 1pf is the .7pF or .3pF going to screw the whole thing? I guess their may be some series combination to make it exactly 4.7pF.
Anyway I don't want to buy any more stuff I have all the resistors and 1/8 and 1/4 watts. I have most of the pF capacitors , I have alot of uf , and some nF. I also have 2N3906 12 pack PNP transistors...etc
Their must be something I can do to easyly fix this.
I tunned into different stations around 87 MHz up to 99.3MHz FM
I tapped the microphone each time but I never got a taping sound out of the car speaker or anything.
The 9 volt battery is new and I check it with a multimeter to see if it was producing around 9 volts ,it was.
The car radio is in perfect working conditions so I am at a loss?
I don't have any bare copper wire if the insulation is screwing up the anttena but I have an old bunny ear TV anntena if that would clear it up.
I tried keeping the coils of wire in the inductor close together but maybe they are still to far apart?
For the varible capacitors should I be tunning more to the 40pF or to the 4pf or to the middle just so I know around how much capacitance I need to be at with my capacitors in parrell.
Thanks for any help
This is bothering the heck out of me. I should get something weather it be my voice with alot of noise. Anyway maybe I put the transistor or mic in the wrong way but I thought I tried ever combination. AHHHHHHHHHHHH
http://www.uoguelph.ca/~antoon/circ/fmt1.htm
However when I try to pick up the signal right out side on my car radio. (or any radio for that matter)
It doesn't work. I have check the connections they all look good.
The only thing I was having problems was with which leg for the 2N3904
NPN transistors was the emitter and collector. I see a small line on top of the transistors I am wondering is this the collector or emitter leg? I am assuming with these transistor the base is the middle as the picture on the back of the package shows.
Also I am using radioshacks part 270-0090 Condensor microphone.
It has one leg that has 3 green lines is this the leg that goes to ground or power side? ( think I tried both )
For the antenna I used around 8 to 12 inchs of 22 gage magnetic wire.
For the inductor I used 10-11 coils around a pencil. I left the pencil in the middle of the inductor coil should I take it out or does it not matter if it's their? I used 22 gage magnetic wire for the inductor as well.
For the capacitors I used 0.01uF and 0.1uF polyester-film capacitors
For the resistor I used 1/8 watt carbon-Film resistors radioshack 271-003 500 pack. This had all the size resistors I need in it. I don't think I need more the 1/8 watt power?
I used a 9volt battery.
The only thing I didn't have is the varible capacitor and the 4.7 pF capacitor. They just didn't have these. But I have alot of 1, 10 , 15 pF cermic capacitors I just but them in parrell to make desired capacitor variations for the varible capacitor. I think I should still be able to get something.
For the 4.7pF I just used 5 1pf or 4 1pf is the .7pF or .3pF going to screw the whole thing? I guess their may be some series combination to make it exactly 4.7pF.
Anyway I don't want to buy any more stuff I have all the resistors and 1/8 and 1/4 watts. I have most of the pF capacitors , I have alot of uf , and some nF. I also have 2N3906 12 pack PNP transistors...etc
Their must be something I can do to easyly fix this.
I tunned into different stations around 87 MHz up to 99.3MHz FM
I tapped the microphone each time but I never got a taping sound out of the car speaker or anything.
The 9 volt battery is new and I check it with a multimeter to see if it was producing around 9 volts ,it was.
The car radio is in perfect working conditions so I am at a loss?
I don't have any bare copper wire if the insulation is screwing up the anttena but I have an old bunny ear TV anntena if that would clear it up.
I tried keeping the coils of wire in the inductor close together but maybe they are still to far apart?
For the varible capacitors should I be tunning more to the 40pF or to the 4pf or to the middle just so I know around how much capacitance I need to be at with my capacitors in parrell.
Thanks for any help
This is bothering the heck out of me. I should get something weather it be my voice with alot of noise. Anyway maybe I put the transistor or mic in the wrong way but I thought I tried ever combination. AHHHHHHHHHHHH
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