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jasonchong0
jasonchong0 • May 26, 2011

RF Transmitter Receiver

Hey all!
I have just constructed a RF circuit to try out. I made use of the T5-434-5V and the R5-434-5-128 transmitter and receiver pair and also the HT12E and HT12D as the encoder and decoder for the transmitter and receiver respectively.

The schemetic I used can be found on page 6 of this datasheet: https://www.spelektroniikka.fi/kuvat/T5R5-434-5V.pdf

After following exactly, the circuit does not work. I connected the DOUT of the encoder and the DIN of the decoder directly and it works, which brings me to suspect it's the RF pair that's not working.

HT12E oscillator resistance: 1M ohm
HT12D oscillator resistance: 51K ohm

If anyone has any idea as to why the transmitting and receiving isn't working, your comments would be greatly appreciated!
Thanks!
Harshad Italiya
Harshad Italiya • May 26, 2011
If you have a doubt on encoder and decoder section then first try to send and receive data without using Encoder and Decoder Chip. It should work properly.
jasonchong0
jasonchong0 • May 26, 2011
Thanks for the quick reply.

I tried removing the encoder decoder section and connect VDD to the Data In of the T5-434. However, I did not manage to get a 5V at the Data Out of the R5-434 when measured with a multi-meter.

I would think that the encoder decoder part should not be the problem in this case. But I may be wrong.
Harshad Italiya
Harshad Italiya • May 26, 2011
Have you applied VDD directly to Data In of T5-434? as they have mentioned that you have to use some CMOS driver circuitry to match the impedance of 45 Ohm.
jasonchong0
jasonchong0 • May 26, 2011
The HT12E and HT12D would help because they have CMOS compatible outputs.
Harshad Italiya
Harshad Italiya • May 26, 2011
jasonchong0
The HT12E and HT12D would help because they have CMOS compatible outputs.
Have you checked there is one small circuit also don't why it is used but i think most probably for impedance matching.
jasonchong0
jasonchong0 • May 26, 2011
Correct me if I'm wrong but do you mean the carrier detect circuit? That would be to indicate if any signal is being transmitted.
Harshad Italiya
Harshad Italiya • May 26, 2011
Actuually they have written that there is one pin which gives the strength of the FM Signal. So we have to check first that our Transmitter is transmitting or not? and by checking strength at that pin we can decide some conclusion what you say?
jasonchong0
jasonchong0 • May 26, 2011
I have tried that without adding the additional circuit, the voltage at the RSSI pin records a reading of approximately 0.5V. This is less than any of the values they gave in the RSSI table. I will try to construct the Carrier Detect additional circuit soon to try out.

But in the mean time, would there be any other possible problems?
Harshad Italiya
Harshad Italiya • May 27, 2011
jasonchong0
I have tried that without adding the additional circuit, the voltage at the RSSI pin records a reading of approximately 0.5V. This is less than any of the values they gave in the RSSI table. I will try to construct the Carrier Detect additional circuit soon to try out.

But in the mean time, would there be any other possible problems?
I think there no other component so it have to work properly don't know if there is any other problem. 😔
jasonchong0
jasonchong0 • May 28, 2011
Alright thank you anyway! 😀

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