433MHz rf module interfacing problem.. plz help

[bobparihar]

I am using a circuitry to send data through wireless.. using RF of frequency 433Mhz
my circuit is as follows
the problem here is that this works but the range is only 2m
i had also attach a wire antenna of about 5cm to both the transmitting and receiving module.. but it does not work

 

[alec_t]

Have you checked the datasheets for the Tx and Rx modules to identify the best antenna configuration?

 

[bobparihar]

iam somewhat confused here.. here in my circuit diagram it uses 750k ohm between the pin n0. 3 and 4 of encoder for oscillator and 27 k ohm at the decoder end..
but in some tutorials i have seen 1M ohm at the encoder and 33K ohm at the decoder..
well i have seen what iam doing in many tutorial too..
can some one explain this? does iam doing somthing wrong?

 

[alec_t]

here in my circuit diagram it uses 750k ohm between the pin n0. 3 and 4 of encoder for oscillator and 27 k ohm at the decoder end.

Your diagram shows the resistors between pins 15 and 16. Are you sure you have the ICs correctly orientated?

in some tutorials i have seen 1M ohm at the encoder and 33K ohm at the decoder.

I don't think the values are critical.

 

[bobparihar]

Your diagram shows the resistors between pins 15 and 16. Are you sure you have the ICs correctly orientated?
I don't think the values are critical.

i have seen in some tutorial the resistance is of 1M ohm at encoder side and a 33k ohm at the decoder side..
i hav also seen 750k ohm at the encoder side and a 27k ohm at the decoder side in some other tutorials...

but i did experimented both and both works..
but the problem is with range

 

[alec_t]

i did experimented both and both works.

That's what I would have expected.

but the problem is with range

Re-read post #2. Short monopoles/dipoles are inefficient.

 

[jjw]

You could try higher supply voltage for the transmitter and l/4 antenna ( - 17cm) in both transmitter and receiver.

 

[atif123]

use this circuit