1. We will be in Read Only mode (no new threads, replies, registration) for several hours as we migrate the forums to upgraded software.

Changing Rx from 12V with relay to 4.5V no relay

Discussion in 'Wireless & RF Design' started by phildupuis, Dec 9, 2009.

  1. phildupuis

    Thread Starter New Member

    Dec 9, 2009
    1
    0
    I'm really new at this so I may not know all the terms at this point.

    Please have patience as I'm learning.
    I purchased a Tx and Rx from ebay that was just a plug and go(came with relays, chip all pre-assembled ready to go), cool... works great! But Rx needs 12V to operate a relay. It drained my batteries.

    -I only wanted to control a small 3V motor (on or off), relay not needed.
    -Wanted it silent, the relay clicked pretty loud - took it out
    -wanted to go down to a lower voltage circuit (3x AAA batteries)
    So I purchased another Tx and Rx from ebay

    • Distance: 100M(330 feet)
    • Type: RF radio
    • Carrier freq. 315MHz
    • Max data rate: 10KHz
    • Power supply: 5V~6V
    • Encoder/Decoder: No
    • Output type: Square wave
    • Size: 20mmx 18mm x 5mm (Tx)
    • Size: 30mm x 20mm x 5mm (Rx)
    I hacked it into the circuit of the other one (because I wrecked the Tx and Rx of the other unit while playing around)


    The transmitter is still using a 12V "23A" alkaline battery from initial unit.

    See attached picture of the circuit for the Rx that I put together.

    It works if I'm really close (2 - 3 feet). Can't get much range.

    The unit used to work at almost a block away in the original state. Is this because I downsized the voltage of the Rx from 12V to 4.5V??

    What can I do to increase the range.

    If I put my multimeter between Ground and the lead before the 3.3K Resistor, I get a reading of 3.8V, if I walk away farther then 3 feet, the current drops down to 0.48V, so the motor sputters.

    Any Ideas? Thank you so much for your help.

    Phil
     
Loading...