hello , i'm trying to do ASK modulation , i've generated a carrier using the circuit attached below , i'm getting a 16 MHz , 3 v p-p sine wave at the emitter , i want to make a simple receiver for my transmitter , i've tried cascading 3 CE amplifiers like in the 2nd attached schematic , but i'm getting no output , how can i design a receiver for this circuit any help is appreciated .

 

Hello,

Did you check if the transmitter is giving any signal?
What are you using as antenna?
The receiver has no selectivity at all.
It will receive all frequencies that are in reach.

Bertus

 

i think it is giving a signal because , my radio gets interference when my transmitter is powered , i'm using 2.5 m of copper wire as my antenna , i'm also connecting output of envelope detector to a LM358 comparator , but i'm getting no signal .

 

Hello,

On this page you will find a lot of serious RF circuits:
https://www.qsl.net/va3iul/Homebrew_RF_Circuit_Design_Ideas/Homebrew_RF_Circuit_Design_Ideas.htm

20 m is about 14 Mhz.
You could tune the circuits to meet your 16 MHZ.

Bertus

 

I'm pretty amazed that a three stage common emitter amplifier for 16MHz isn't just an oscillator. The fact that it isn't rather suggests the amplifier is seriously lacking gain for some reason.

 

As there is no supply decoupling I think it is almost certain to oscillate.

Les.

 

As there is no supply decoupling I think it is almost certain to oscillate.

Les.

why would it oscillate ? i thought there needs to be positive feedback for a circuit to oscillate .

 

Hello,

On this page you will find a lot of serious RF circuits:
https://www.qsl.net/va3iul/Homebrew_RF_Circuit_Design_Ideas/Homebrew_RF_Circuit_Design_Ideas.htm

20 m is about 14 Mhz.
You could tune the circuits to meet your 16 MHZ.

Bertus

i've looked at these circuits , they seem very complex for me to make or understand at this point ,my transmitter and receiver are 2 meters apart , is there any way i can make a simple receiver to detect my signal ?

 

why would it oscillate ? i thought there needs to be positive feedback for a circuit to oscillate .

Yes, and unless that circuit was made with very careful routing and decoupling as it would have a gain around 1000, very little signal would need to be coupled back into the input to make another transmitter!

 

hello , i'm trying to do ASK modulation , i've generated a carrier using the circuit attached below , i'm getting a 16 MHz , 3 v p-p sine wave at the emitter , i want to make a simple receiver for my transmitter , i've tried cascading 3 CE amplifiers like in the 2nd attached schematic , but i'm getting no output , how can i design a receiver for this circuit any help is appreciated .

https://forum.allaboutcircuits.com/threads/common-emitter-amplifier-design.159006/#post-1383947

lol..your ask still not working

 

This one is sort of a glorified crystal set. Just replace the components in the resonant circuit with a LC pair that resonates at 16 MHz. The output is what is connected to the ATTINY12 -connect that to whatever high impedance load you like. Only build the circuit to the left of the ATTINY12. A 2N3904 should work fine at 16 MHz. An MPSH34 or KSP10 a little better because of lower input capacitance.



Tuning is tricky. I tuned this by spreading and compressing the inductor because I didn't have any suitable trimmer capacitor. It would be easier with a trimmer. I think the values shown put the center frequency near 100 MHz (that was along time ago!)

Consider changing your operating frequency to an ISM (Industrial, Scientific, Medical) band such as 13.56 MHz ±14 kHz or 26.957 to MHz 27.283 MHz where you will be unlikely to affect licenses services. Crystals for those bands are readily available and inexpensive.