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Thread: RC help

  1. #21
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    Jun 2004
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    Pune
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    i have pic-axe 18x.. so the uC is pic 16F88....

    ok.. so i know now how not to damage the thing.. but how do u improve the range??... also what for bi-directional capability?...

    i seem over-anxious but.. pls forgive me..

    thx a lot
    mandar

  2. #22

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    Hi mandar,
    i did not get clear picture about circuit. anyway.. you can connect motor to pic using h-bridge ic (L293D) . i mean disconnect the motor from rx.changing the output of pin connected L293D you can reverse the speed. connect the output of rc receiver to pic.
    as for increasing the range, may be u have to do something like increasing the power of signal at transmitter.

    as for -ve voltage problem i think pic should read it as logic 0. other wise u can try by connecting a pnp transistor to the input pin of pic such that emitter is connected to pic. -ve voltage from rx is connected to base and collector is connected to ground. when -ve voltage is applied at the base transistor turns on and pin connected to it is grounded. the concept here is to use transistor as a switch. i am not sure about this. i request other member to correct any mistake.

    subot_robot

  3. #23
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    Sep 2004
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    Ahmedabad/India
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    For increasing the range do the following :

    1) Tune the circuit ( the ferrite beads - make them move slowly in out)
    2) Use a matching antenna.( use whip aerials - try using cordless phone whip )
    3)try to keep RF block as far as possible from other electronics.

    -
    Pulkit

  4. #24
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    sorry for being unclear.... my problem is not abt reversing the motor... i know how to make that happen.... ok.. let me first clear up some things..

    i have o/p of rx connected to uC.. and some pins of uC connected to l293d.. which then give o/p to motors...

    now... when i say fwd from the tx.. one wire of o/p of rx goes high .. the uC sees this and then drives the motor fwd... (by changing some code i can drive it backward.. so the prob is different)

    when i say reverse from tx.. the o/p of rx which went high earlier changes to -ve.... so.. the gnd wire of rx always stays gnd while the other pin changes betwn +ve and -ve...

    i was hoping that the gnd and +ve states get interchanged when i reverse. but since only one pin is changing state.. i cant tell the uC to reverse it....
    thats my prob..
    hope that makes things clear

    i dont think the switch idea will work.. coz it wont be able to differentiate between and zero and a -ve..
    thnx a lot
    mandar

  5. #25
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    hey pulkit.. i was sitting next to the comp..when i tried the range.. maybe that was a prob.... will trry far away from it..

    also there was no antenna for rx.. (if thats what u meant ).. i'll also try tuning and post result tomo...

    thanks a lot

    mandar

  6. #26
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    Pune
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    in trouble again

    well i did try the remote control away from the comp and the range increased to around 5 feet.. pretty ok i guess..

    to connect it to uC.. i tried using a comparator.. LM339.. since i have two motors and the thing will give only 0-1 o/p .. i used all for comparators (so that reversing is possible..)

    but that comparator now refues to give any o/p....!! .. also the ckt diag in the article given by vikas shows 20 and -20 supply...so if i give a 5- 0 v supply will it work?... or that is no way related to my problem
    btw i bought two lm 339's and both dont work.. so i guess im messing up my ckt?.. i feel its the voltage given to it..

    am i right?.. and what do i need to do?

    thanks a lot
    mandar

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