4 channel rf transmitter receiver.. help pls!

[BoB_the_BoT]

hi

i'm trying to build a 4 channel rf transmitter receiver to transmit 4 data pins from the serial port of the computer to my robo.

Before connecting the serial port pins, i wanted to test the rf circuitry.
i've used the circuits shown in : http://home.att.net/~wzmicro/rf.html .. with the differences that i've connected +3v for the AD pins of encoder (HT12E) that i want to transmit and that i've used the AM 433Mhz transmitter and receiver shown in : http://home.att.net/~wzmicro/rf_xmitter_receiver.htm , instead of the WZ-X01 and wZ-R01 shown in the circuits.

i've used 3.1v batt (using 2 AA cells) for the transmitter side and 4.8 v batt (3 AA cells) for the receiver side.
Also, for the sake of testing, i had connected 4 LED's to the 4 output pins of the decoder (HT12D). Neither them nor the valid transmission pin (pin 17 of decoder) showed any signs of success. 

pls help

[4by4]

Your question is too broad. How much troubleshooting have you done? I would test the encoder/decoder separately from the transmitter/receiver. First check if the encoder is outputting data. Then set up the transmitter and receiver pair and input a logic high and low. See what the receiver outputs. Also check the decoder separately. Once you get all that working then connect them together.

[Soeren]

Hi,

[...] to transmit 4 data pins from the serial port of the computer [...]

Even though you haven't done it yet, beware that the serial port use +/-12V signals, so you need a level converter for that.

i've used the circuits shown in : http://home.att.net/~wzmicro/rf.html .. with the differences that i've connected +3v for the AD pins of encoder (HT12E) that i want to transmit

Are you aware that, in the schematic, it is coupled so the HT12E is powered continuously, but the transmitter is only grounded (through D1 to D4) when a button (S1 to S4) is pressed?

and that i've used the AM 433Mhz transmitter and receiver shown in [...]
Also, for the sake of testing, i had connected 4 LED's to the 4 output pins of the decoder (HT12D). Neither them nor the valid transmission pin (pin 17 of decoder) showed any signs of success. 

I guess you don't have an oscilloscope, which would make it a 5 minute job to find the fault?
If you probe the DOUT-pin of the HT12E with a DMM (in the 20V range Try both AC and DC) what does it read?

You really have to approach your problem in a modularized way. First verify the encoder, then the transmitter, then the receiver and finally the decoder.

[BoB_the_BoT]

thanks u guys...
i'll test each of these components separately like u guys have said and get back..

@soeren
thanks for the facts on serial port voltage and the transmitter grounding ... didn't notice them.