thanks for the quick reply.
why i choose that BA1404 is bcz it uses less no. of components and the site has pcb layout(at which i always sucks).still i'll try BH1417.
and if u have any more stereo transmitter ideas pls let me know
thanks once again.
You said you want a simple design. Cheap toy transmitters have a simple design.
1) Their RF frequency drifts if anything gets near it.
2) Their audio beats with the stereo 19kHz pilot frequency causing distortion and odd noises.
Hi,
Just want to make sure, this (mod4) FM transmitter, the input voice signal is amplified, its output to the oscillator is 180 degree out of phase from the mic input right? Then at the antenna part, another amplifier to amplify the modulated signal then invert the signal again to get back the same phase as the original signal? Or the phase doesn't matter?
Okay, thanks!
My field strength meter shows only 40mV maximum, when the meter antenna is very near to the transmitter antenna. Both of the antenna are around 70cm long. But you told me that yours can up to a few hundred mV isn't it?
The emitter resistor reduces the voltage and the current for the output transistor. Power is voltage times current so the power output and heat are both reduced a lot.
My Mod4 FM transmitter has a range of "across the street" to a cheap FM radio.
Its range is about 200m to my cheap Sony Walkman FM radio with its antenna attenuator set to "distant".
Its range is about 2km to my very sensitive home stereo and my very sensitive car radio with nothing in between.
10km range will need a very sensitive radio and enough output power to cause interference and is probably against the law without a licence. If you make it yourself then you won't be able to licence it.