How to change transmitter frequency

Discussion in 'General Electronics Chat' started by 5&under=sorcery, Sep 20, 2010.

  1. 5&under=sorcery

    Thread Starter New Member

    Jul 4, 2010
    28
    0
    [​IMG]I found this neat little hand held transmitter/receiver kit that solved all my problems on my electric gate project. It even reverses a DC motor on demand so with the addittion of some auto-stop circuits I designed the gate now operates just fine. The problem is the kit comes with two small transmitters and that's all I can get because the kits share 500 different frequencies. I need two more transmitters. RF stuff is way out of my job description but from what I THINK I've picked up over the last few months the frequency is controlled by a germanium crystal. The picture is a transmitter of the same basic kind mine are. Is the silver disc the crystal? Can one find out what the frequency of the 2 transmitters that work are and put like crystals in two identical (except for the crystals) transmitters? Where would I obtain matching crystals? Does one have to use a scope to get the frequency or do the numbers on the crystal reveal the frequency? Thank you.
     
  2. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    No. They operate on the same frequency.

    Your photo shows an encoder IC commonly used in wireless remote controls. Its job is to generate data encode with different address/data so the corresponding receiver can match the received address/data to see if the correct transmitter is in use. The round silvery thing is actually the transmitter.

    The data sheet of the HS2262 IC is also attached in this post if you fancy a look at it.

    The following is a clip from the data sheet, showing how one can program the address of the IC. There are links or solder pads underneath the board which user can bridge using solder to select any of the three choices of a. to positive, b. leave open and c. to 0V. Thus one address line allows three possible choices and there are 8 address pins available on the IC.

    Shows us the bottom view of your transmitter and we might be able to point out to you where these links/pads are. If you want 4 transmitters for your gate just made sure all the transmitters are of the same type. Look very carefully at the bottom PCB traces of all four to ensure all of them has solder in the same spots all around. This will make them transmit the same address/data code.

    [​IMG]
     
  3. 5&under=sorcery

    Thread Starter New Member

    Jul 4, 2010
    28
    0
    Friend Chung, THANK YOU. Your answer was straight forward and understandable. I changed the two incorrect transmitters over to the correct code and they work fine. I can still hardly believe it was that simple. You solved a big problem for me. Thanks again, Doug
     
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