the problem is, my local electronics store doesn't supply the BH1417F like in the silicon chip magazine. But still, it looks like a nice circuit. I don't want to be a nuisance, but you don't perhaps have schematics of a simpler transmitter that is made of commonly availible parts.
As always, thanks for the help to the newbies like me.
Talking Electronics have published lots of good books which are cheap and packed with FM bug circuits and ideas. You can still mail order their books and kits http://talkingelectronics.com/
is it possible to use any kinds of "black transistor" for an Fm transmitter? For example s8550!! I didnt mean that in a racial way nor black skin or white skin! He said "use a black one" and thats definitely rude
A Wing Shing S8550 PNP transistor is not black, it is Oriental.
I have never seen one since I use American 2N3904 NPN transistors that work at a frequency that is double the max frequency of the S8550.
I went to China to find a UTC datasheet for their S8550 transistor. It shows no skin colour so it might be purple instead of black.
It might not work as an FM transmitter because some of them have a gain of 1 (like a piece of wire) at 100MHz and won't oscillate at frequencies up to 108MHz.
I went to China to find a UTC datasheet for their S8550 transistor. It shows no skin colour so it might be purple instead of black.
It might not work as an FM transmitter because some of them have a gain of 1 (like a piece of wire) at 100MHz and won't oscillate at frequencies up to 108MHz.
is BC547 better than 2n3904 for low power RF amplifier? And I have seen the fm transmitter you have posted using 3 or 4 2n3904 so whats the range of the transmitter?.
is BC547 better than 2n3904 for low power RF amplifier? And I have seen the fm transmitter you have posted using 3 or 4 2n3904 so how many long it could be reach?
My FM transmitter is fairly low power so a BC547 will work the same as my 2N3904.
"How many long it could be reach" does not make sense in English. Maybe you are asking how far away it can be received which we call "its range"?
I tested it across a large river valley with nothing in between. It was more than 2km to my expensive very sensitive FM stereo and my very sensitive car radio, it was about 300m to a cheap portable Sony Walkman FM stereo radio and it was across the street to a cheap FM radio from The Dollar Store (it uses a TDA7088 FM radio IC). The Dollar Store sells very cheap Chinese and Indian junk). In my neighbourhood houses and trees reduced the range a lot.
The transmitter antenna was 80cm long and hanged vertically out an upstairs window. My FM stereo and car radio antennas were also long and arranged vertically. My Sony Walkman radio uses its earphones cord as the antenna (not good) and the radio from The Dollar Store has a whip antenna that is much too short at about only 12cm (it picks up only strong local stations but is also overloaded by many of them).
Many cheap FM radios are overloaded by strong local stations so the range will be reduced a lot. My cheap Sony Walkman radio has a local-distant switch that attenuates the antenna input when switched to local. When overloaded a station appears at many points across the dial.
When my transmitter is close to a cheap radio then it appears at many points across the entire dial.
you could make a long range transmitter if u try because u are a very experienced guy in electronics. but why u still playing with those old and cheap 2n3904 transistors? Have u ever tried to make one for a higher power or failed to?
Don't you know that it is illegal in most countries to make a powerful radio transmitter (more than a few mW output)? You must have a licence which shows a certain frequency (if a frequency is available) and the circuit must be certified to have excellent spec's.
My FM transmitter that uses 2N3904 transistors is much too powerful (its output is about 20mW to 100mW) and its frequency is not very stable.
I tested my transmitter for only one hour because it caused interference to cheap nearby radios and I was afraid that somebody might complain and send the RF cops to catch me illegally transmitting without a licence. I never used it again.
My simple transmitter was my fix of one that somebody posted and didn't work. I biased everything properly, added the output transistor to separate the antenna from the oscillator, added a voltage regulator and added pre-emphasis.