IR sensor and a DC motor

Discussion in 'General Electronics Chat' started by Jonasz, Aug 26, 2016.

  1. Jonasz

    Thread Starter New Member

    Aug 26, 2016
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    Hi, I'm making a paintball pistol with a electronic loader for 50 rounds :D
    It is almost complete, just need a simple circuit to finish
    I never made a circuit before or studied electronic, that is why I'm seeking for help

    I need a very simple circuit, Just a IR sensor that make a DC motor run when it receives IR light



    That is what I tried to do:
    Motor nao gira.jpg

    But the motor does not run :(


    With a white Led instead the DC motor the circuit works

    If I curt-circuit from the collector to the base on the transistor the DC motor works


    What should I do?

    Sorry for my bad english, I'm from Brazil
    Thanks
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Do you mean it works when the white LED is oriented in the opposite direction compared to the diagram, so that it conducts and lights?

    What IR diode are you using? That term is usually used for something that emits IR light, not receives it. Even if it is a receiver, it probably cannot pass enough current to turn the transistor on and run the motor.

    There are several solutions depending on what you have available. A darlington transistor (two transistors) to replace the 2N3904 may be the simplest, if your diode truly is a receiver.
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Welcome to AAC!
    In a 'very simple' circuit the LED will respond to normal daylight. Is that what you want? If you instead want to send a command to operate the motor then bear in mind that IR remote controls for TVs etc use transmitter and receiver modules which work with pulsed ultrasonic-frequency (typically ~38kHz) IR signals.
    Take a look at this to get an idea of what is involved.
     
    Last edited: Aug 27, 2016
  4. wayneh

    Expert

    Sep 9, 2010
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    @Alec_t, can you really get enough current thru a generic LED to make that circuit work? I guess it depends somewhat on that motor.
     
  5. Alec_t

    AAC Fanatic!

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    I very much doubt it.
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
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    AFAIK: the TV front panel IR receiver chips also respond to steady light and produce similar to an open collector TTL output.

    As long as my theory is right; it'd work very nicely with a logic level MOSFET.

    You have to regulate its supply, but a 78L05 doesn't take much space - every one I've seen on a TV front panel had a local 100R resistor and a small decoupling electrolytic, its probably for all the digital hash in modern TVs, but I'd duplicate it just in case.
     
  7. AnalogKid

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    Aug 1, 2013
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    What he said is that when he replaces the motor with a white LED, the white LED comes on when the photodiode is illuminated. My guess is that there is enough base current to turn on an LED with 5 mA, but not run a motor with 200 mA. If a 3904 can handle the motor current, what about a 2N7000 instead, with a 1 M pulldown resistor on the gate?

    ak
     
    Last edited: Aug 27, 2016
  8. Jonasz

    Thread Starter New Member

    Aug 26, 2016
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    3
    Thanks for the answers

    I asked for the seller for a IR receiver
    If I use a led instead a motor it works:
    Led acende.jpg


    If I curt circuit the receiver the motor run:
    Motor gira.jpg



    A guy told me to use this circuit
    BC337.png
    on the Q2 use a IR receiver

    It works with a led, But with the motor the BC337 fried.
    So he said to use a darlington

    2N3904 and MPSA13
    or
    BC548 and BD 139

    Moonday I Will buy and test it



    Yes
    Simple is better
    More sensible is better too

    I was even thinking about to use a LDR, but It would not fit. a 3mm IR receiver fits better


    I dont know How to make a pulldown, Is like that?
    2N7000 .jpg

    --------------
     
  9. ci139

    Member

    Jul 11, 2016
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    related reading see Photodiode Tutorial TAB
    ▲ they have science equippement that is quite expensive and specific -- there's some afordables also:
    Wavelength Range λ 350 - 1100 nm
    Peak Wavelength λP 980 nm (the red light ends 700nm - so it's iR or near-iR)
    there are a lot of problems getting this right and working - such as - daytime direct intense sunlight (may saturate your sensor and trigger it)
    the other factors - beam distance focus direction - what they use in TV remotes is modulated infrared pulses that get to iR sensor through proper light filter - and trigger nothing unless the encoded signal sequence matches the expected command - perhaps it not required if your setup is simple enough . . .
     
  10. Jonasz

    Thread Starter New Member

    Aug 26, 2016
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    Light interference is not a problem, it will stay in the dark inside the bolt chamber on the paintball pistol. the beam distance will be just one inch
     
  11. ian field

    Distinguished Member

    Oct 27, 2012
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    The problem seems to be; it works with a LED load - but not a motor. Using a Darlington might possibly fix that. The MOSFET solution could work - but just stating 1M pulldown may not work straight off. There wouldn't be any problem turning the MOSFET on, but compensating for PD leakage due to any ambient light that sneaks in, may take a bit of trial and error.
     
  12. Jonasz

    Thread Starter New Member

    Aug 26, 2016
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    is there any option to try with the actual inventory?

    TIP42
    TIP42
    2N3904
    2N3904
    BC337
    BC557c
    IR sensor
    pot 100k
    pot 20k
    resistance 10k
    resistance 1k
    resistance 390
    resistance 390
     
  13. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Yes. I should have been more clear - a 2N7000 or 2N7002 is a small N-channel MOSFET, almost like the FET equivalent of a 2N3904. To turn it on takes a higher voltage at the gate, but the gate current is almost 0 mA. For a very low current sensor like a photo diode, it might work better than a bipolar transistor.

    ak
     
    Last edited: Aug 28, 2016
    MaxHeadRoom and wayneh like this.
  14. ci139

    Member

    Jul 11, 2016
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    to play silly smart-S - its like a darlington of two 2N3904 (only slower - muhahahahaa) - so it's more sensitive . . .
     
  15. ian field

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    Darlingtons are not known for being particularly fast. The only thing that significantly slows a MOSFET is the small magnitude of the photocurrent charging the gate capacitance.
     
  16. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Do you need ultra hi speed?:rolleyes:
    Siliconix labeled the original 2n7000 as a 'Fetlington' as it compared to a cross between a darlington with FET characteristics.
    Max.
     
  17. ian field

    Distinguished Member

    Oct 27, 2012
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    With a bare PD; it may be worth considering a voltage follower - you can use a lower G/S shunt resistor for faster discharge of gate capacitance.
     
  18. wayneh

    Expert

    Sep 9, 2010
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    Another issue with that circuit is that the motor will respond very quickly to the IR diode signal, which is not debounced. Depending on the application it may make sense to use a 555 monostable to debounce the input and make sure the motor runs some minimum length of time after a signal is detected. Likewise on the input, something like an RC integrator on a comparator input would prevent possible chatter from an occasional flash of light, for instance. And that's another thing, the sudden battery voltage dip when the motor turns on will cause havoc on the PD sensor output.
     
  19. ian field

    Distinguished Member

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    AFAICS: the TS hasn't been *EXACTLY* clear on the intended switching mode - but its most likely that its supposed to switch on and off cleanly rather than any kind of linear action. I'd go for an LM358 with one stage as voltage follower and the other as Schmitt trigger.

    A non-retriggerable monostable might avoid the need for a Schmitt, but unless they're using SMD parts - a single op-amp isn't any smaller than a dual.
     
  20. wayneh

    Expert

    Sep 9, 2010
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    Yes, there are many options for solving the various problems. I'm not sure the TS is aware of the problems yet.
     
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