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*STOP PRESS* Coronavirus. A lot of Clubs have already cancelled all activities. Check carefully before you plan any travel

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CANCELLED because of coronavirus. Papplewick Pumping Station, Nottingham, Sunday 12th & Monday 13th April
CANCELLED because of coronavirus. Bournville Sub Day, Sunday 10th May 2020

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(CANCELLED) Submarine, Boating & Sailing Weekend, Norwich MBC, Weekend of 25,26th July

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Model Boat Convention, Haydock Park (Cancelled this year)

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CANCELLED. Bournville Sub Day, Sunday 13th September

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(CANCELLED) Club Submarine Regatta, Furness MBC, Barrow in Furness, Sunday 20th Sept 2020

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» openLRS and 2.4 Ghz and Submarines
Transmission of servo (pwm) signals through water and clear plastic EmptyYesterday at 9:52 am by david f

» Italian CB class from WW2
Transmission of servo (pwm) signals through water and clear plastic EmptySat Sep 12, 2020 10:30 am by david f

» Last event cancelled for 2020
Transmission of servo (pwm) signals through water and clear plastic EmptySat Sep 05, 2020 10:31 am by david f

» Simple telemetry system for openLRS (on 458Mhz)
Transmission of servo (pwm) signals through water and clear plastic EmptySat Aug 29, 2020 1:53 pm by david f

» John Lambert Plans
Transmission of servo (pwm) signals through water and clear plastic EmptyThu Aug 13, 2020 11:51 am by david f

» Piston Tank - Depth Control (Paper by Wolfgang Baumann & Helmut Huhn)
Transmission of servo (pwm) signals through water and clear plastic EmptyThu Aug 06, 2020 9:17 am by david f

» Krick Type Vll B Wiring and build photos
Transmission of servo (pwm) signals through water and clear plastic EmptyTue Jul 28, 2020 8:02 am by Deep Diver (Fred)

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Transmission of servo (pwm) signals through water and clear plastic EmptySat Jul 11, 2020 9:34 pm by timgarrod

» PIC and Arduino microprocessors
Transmission of servo (pwm) signals through water and clear plastic EmptyThu Jul 09, 2020 10:59 pm by timgarrod

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    Transmission of servo (pwm) signals through water and clear plastic

    david f
    david f
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    Transmission of servo (pwm) signals through water and clear plastic Empty Transmission of servo (pwm) signals through water and clear plastic

    Post  david f on Sat Jul 05, 2014 12:43 pm

    I am just putting the components away for something I was trying with the original Darnell XXI. I originally needed to send a servo signal through a clear, flat plastic hatch. I dropped the idea later as you will see in the Darnell XXI thread.

    But the method I tried worked well and was very simple.

    The sender unit (connected to the receiver) was just an Infrared LED with a 30 ohm resistor in series (just to limit the current. The receiver unit (connected to the servo) was a photodiode with a 1 megohm resistor in series. (The LED and photodiode were a matched pair but I can't remember where I bought them from. Ebay probably.)

    The early trials were surprisingly successful with the signal being happily beamed through several mm of plastic or even water.

    If you used a separate 5v supply at the receiver end then that is just one wire to transmit a servo signal.

    David

    salmon
    salmon
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    Transmission of servo (pwm) signals through water and clear plastic Empty Re: Transmission of servo (pwm) signals through water and clear plastic

    Post  salmon on Sun Jul 06, 2014 7:35 pm

    Is that all it took was a resistor connected directly to the infrared led? No complicated circuits? Am misunderstanding?
    Thank you for posting this! Makes the brain work.


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    david f
    david f
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    Transmission of servo (pwm) signals through water and clear plastic Empty Re: Transmission of servo (pwm) signals through water and clear plastic

    Post  david f on Mon Jul 07, 2014 2:40 pm

    Yes, it really is that simple. I've just connected it up again to remind myself.

    One side of the photodiode (the side without a flat on it) is connected to +5v.
    The other side of the photodiode is connected to the white signal wire of the servo and one end of the 1 megohm resistor. The other side of the resistor goes to earth. (It's a pull-down resistor.)

    To "connect" the signal wire you would just need to push the led and diode into the end of ,say, some silicone tube.

    It should have wide application to model subs but, in my case, I bunged everything in a single WTC so the need for it disappeared!

    It is not particularly original - I'd seen the idea somewhere on the web in connection with robotics perhaps as an "optoisolator". The real optoisolaters are no good to us because they are encapsulated in a single device.

    David
    salmon
    salmon
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    Transmission of servo (pwm) signals through water and clear plastic Empty Re: Transmission of servo (pwm) signals through water and clear plastic

    Post  salmon on Mon Jul 07, 2014 3:01 pm

    Thank you David! I have heard that running a servo a long distance from the receiver causes problem with interference. This might be good for keeping a servo in a remote location on the sub. Definitely something to play with!


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    david f
    david f
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    Transmission of servo (pwm) signals through water and clear plastic Empty Re: Transmission of servo (pwm) signals through water and clear plastic

    Post  david f on Mon Jul 07, 2014 4:18 pm

    Your comment has made me think of something else.
    Long servo leads can indeed give interference. I wonder if the light signal can go down a fibre optic cable?

    David
    salmon
    salmon
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    Transmission of servo (pwm) signals through water and clear plastic Empty Re: Transmission of servo (pwm) signals through water and clear plastic

    Post  salmon on Tue Jul 08, 2014 12:29 am

    Exactly what I was thinking!


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