433MHz Wireless transmitter and receiver problem

Discussion in 'The Projects Forum' started by hunterage2000, Jan 10, 2014.

  1. hunterage2000

    Thread Starter Active Member

    May 2, 2010
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    Hi, i recently bought the attached 433MHz Wireless transmitter and receiver modules and I have a problems, at present:

    1) I tested the modules with a 555 square wave signal transmitted to the receiver with an LED on the same 5V regulated power supply.

    I have 1 LED connected directly to pin 3 which flashes brightly but the LED at the receiver output is dimmer and turns on when the LED at pin 3 is off

    Do I need any additional circuitry to regenerate the signal and to improve the transient response, if so what?
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    An NPN transistor and a resistor in a common emitter configuration will invert and amplify the output on the receiver.

    Ken
     
  3. hunterage2000

    Thread Starter Active Member

    May 2, 2010
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    When you say invert you mean both LEDS will flash in sync? Is there a way so there is a slight delay from input tx to output rx?
     
  4. nerdegutta

    Moderator

    Dec 15, 2009
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  5. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Yes. Can you be more specific as to "slight"? And, how is the LED connected at the Rx's output now?

    Ken
     
  6. hunterage2000

    Thread Starter Active Member

    May 2, 2010
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    sorry I meant when the 555 output goes high as a step signal I imagined that the output on the receiver would go high milliseconds after. I don't really know much about wireless comms but am I right in thinking that the 433MHz frequency is the carrier signal and the data can be any frequency from DC to 433MHz?

    Thanks for that link nerdegutta I will take a look soon.
     
  7. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    From my limited experience there is a limit to the data rate. Likely in the low RS-232 bit rates. It might help if you told us what you are trying to do.

    It's often easier for us to help solve you problem, than help solve you solution. ;)

    Ken
     
  8. hunterage2000

    Thread Starter Active Member

    May 2, 2010
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    All sorts of stuff really. From replacing wired circuits with wireless ones from simple press a button and turn on an LED to wireless measurement systems.
     
  9. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Probably then, one answer will not fit all functions. Reading nerdegutta's link, and the associated links in that, would be a good start.

    Ken
     
  10. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    I have a pair I experimented with a bit. Battery supply on the RX and battery on the Tx. I found that with a continuous voltage input on Tx I would get a single, short pulse output on the Rx. That pulse width would limit your data rate. I then used a 555 astable on the input of the Tx to get a continuous output on the Rx. But, I noticed that what looked like environmental noise was intermittently pulsing the Rx output. I then put the Rx output through a LM567 tone decoder, and matched the 555's output frequency to the 567's center frequency. No more spurious output pulses on the Rx. Multiple selected frequencies from the 555 on the Tx and multiple 567s on the Rx would give you multiple on-off channels. Or one microcontroller on Tx input and Rx output could give you multichannel switching or a data transfer channel. maybe even both with a slow bit rate. I got about 125 feet for max reliable communications.

    Ken
     
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