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Battery powered switch

Discussion in 'Electronic Design' started by James, Aug 19, 2004.

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  1. James

    James Guest

    Hey all,

    I need to build/buy a small, cheap, battery powered system which will
    allow me to turn on/off another battery-powered apparatus remotely.

    I have a small battery-powered radio which is behind closed doors.
    The radio runs off a single 9-volt battery. For reasons I won't get
    into, I can't easily get to the radio at all times of the day to turn
    it on and off. Ultimately, as it goes now, the radio remains on at
    all times, basically until I can get to the radio at the end of the
    day to turn it off, or until the battery dies and I go back in to
    replace the battery thus starting the cycle all over again.

    I was wondering if there was a way for me to create or buy a remote
    receiver (I guess it would need to be RF or something similar, since
    IR won't work through the door) which could listen to a remote signal,
    and switch on/off the radio circuit, alternately cutting
    off/connecting the power supply.

    Ideally, this receiver would be battery-powered, and would not draw
    much power at all (so it could stay up and listening for days or weeks
    on end). It could draw from its own separate battery. And, it would
    need to connect to the radio circuit so the radio could be turned "on
    and off" appropriately.

    Sound like something easy or cheap?

    Thanks,

    James
     
  2. Is AC power available in the room where the radio is?
     
  3. James

    James Guest

    Unfortunately, no. Both radio and receiver need to be battery powered.
     
  4. If it were convenient, I'd guess he'd use it.

    When I read it, I was kind of imagining a "barn situation" where one might put a
    1970's style 5D-cell radio up in the rafters in the morning to get good overall
    speaker coverage to wherever one was working around at during the day and where
    power isn't available without stringing long extension drop cords that might
    just get in the way. When one leaves the area for a time (say, to go slop the
    hogs, for example), it would be nice to just point a controller at it and turn
    it off to save battery juice until working back in the barn area.

    Jon
     
  5. Ken Taylor

    Ken Taylor Guest

    Try something like this:
    http://www.smarthome.com/4000.html

    However it's relatively expensive for the task - you might prefer just to
    search using a term like "wireless remote control".

    Ken
     
  6. Ken Taylor

    Ken Taylor Guest

    Sorry, that unit isn't any good for what you want, unless you pretty well
    took it apart and re-engineered it (confession - I didn't read very far into
    the page!) :) However the search term should turn something up.

    Cheers.

    Ken
     
  7. mike

    mike Guest

    UR story sounds more than a little suspicious. Why not just put a
    switch with a sign on it so the people behind the door can turn on the
    radio when they want to listen to it??? Make it a timer so it shuts off
    after a time.

    If you want to monitor people without their knowledge or consent, your
    local spy shop can set you up with all manner of neat toys.
    mike

    --
    Return address is VALID.
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    Bunch of stuff For Sale and Wanted at the link below.
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    http://www.geocities.com/SiliconValley/Monitor/4710/
     
  8. James

    James Guest

    It is similar to that. Basically we have a small (for lack of a better
    word) outlet box near a back wall of our building. The outlet box actually
    houses connections to a set of external speakers that have been wired
    throughout parts of the building. There isn't any power that is running
    through the outlet box (I suppose we could run power there, but the cost of
    getting someone to do that would far exceed the amount of money I want to
    spend on this). Anyways, each speaker throughout the building has its own
    power switch so if we wanted to turn off the sound in, say, my office, I
    could just flip off the speaker itself. The outlet box door is pretty well
    surrounded by equipment in the storage room, so getting into the box is
    somewhat of a pain as you try to maneuver around equipment, etc., so for
    the most part, I just leave the radio on all day long, and let people turn
    off their speakers when they don't want to listen.

    Recently, I have really been the only one using the radio (it just plays
    sports radio all day long), so I can pretty easily turn on/off the radio
    whenever I want -- but only if I can get inside the box.

    Anyways, long story short, I want to be able to set up a remote system
    where I can just send some kind of remote signal from inside/just outside
    the storage room to the receiver inside the (blocked or closed) outlet box.
    The receiver should take any incoming signal and allow me to
    connect/disconnect the radio from its battery power source. Finally, the
    receiver should run on battery power (since there isn't a readily available
    power source) and shouldn't require too much power since it will basically
    need to be on at all times. If I only needed to get to the box once every
    few days or a week to change the battery on the receiver, that'd be good
    enough. As it is, I get about a 14 hours on the radio with the 9volt,
    which means I am either changing the battery daily, or going in to the
    outlet box several times a day.

    TIA,

    James
     
  9. James

    James Guest

    Suspicious or not, that's what I need. See my previous post for more
    details of the situation at hand. The door isn't a door to another room in
    the building, but a door to a small outlet box wired to speakers throughout
    the building.

    James
     
  10. Can you run a _low voltage_ power wire to the radio, and switch it from a
    more convenient location? Even a power wire from a battery box to the
    radio?
     
  11. Genome

    Genome Guest

    | It is similar to that. Basically we have a small (for lack of a
    better
    | word) outlet box near a back wall of our building. The outlet box
    actually
    | houses connections to a set of external speakers that have been wired
    | throughout parts of the building. There isn't any power that is
    running
    | through the outlet box (I suppose we could run power there, but the
    cost of
    | getting someone to do that would far exceed the amount of money I want
    to
    | spend on this). Anyways, each speaker throughout the building has its
    own
    | power switch so if we wanted to turn off the sound in, say, my office,
    I
    | could just flip off the speaker itself. The outlet box door is pretty
    well
    | surrounded by equipment in the storage room, so getting into the box
    is
    | somewhat of a pain as you try to maneuver around equipment, etc., so
    for
    | the most part, I just leave the radio on all day long, and let people
    turn
    | off their speakers when they don't want to listen.
    |
    | Recently, I have really been the only one using the radio (it just
    plays
    | sports radio all day long), so I can pretty easily turn on/off the
    radio
    | whenever I want -- but only if I can get inside the box.
    |
    | Anyways, long story short, I want to be able to set up a remote system
    | where I can just send some kind of remote signal from inside/just
    outside
    | the storage room to the receiver inside the (blocked or closed) outlet
    box.
    | The receiver should take any incoming signal and allow me to
    | connect/disconnect the radio from its battery power source. Finally,
    the
    | receiver should run on battery power (since there isn't a readily
    available
    | power source) and shouldn't require too much power since it will
    basically
    | need to be on at all times. If I only needed to get to the box once
    every
    | few days or a week to change the battery on the receiver, that'd be
    good
    | enough. As it is, I get about a 14 hours on the radio with the 9volt,
    | which means I am either changing the battery daily, or going in to the
    | outlet box several times a day.
    |
    | TIA,
    |
    | James
    |
    | |
    | > When I read it, I was kind of imagining a "barn situation"...

    I'd suggest you figure out how the speakers are actually wired.

    If it's not a '100V' system with transformers and the speakers are in
    parallel then you might consider moving the radio to your office and
    connecting it to your speaker terminals.

    Such a method may be feasible even if transformers are used, your
    speaker transformer becomes the main one.

    Anyway there must be a way of achieving what I'm suggesting.

    DNA
     
  12. James

    James Guest

    I was going to try to do that, but I'd rather not do anything to mess with
    the wiring already in place. Management is a bit wary about people hacking
    away at their speaker wiring system (it was originally installed as a means
    to send messages throughout the building a long time ago) and sometimes
    gets used for legitimate business purposes once every few months. (And
    sometimes to pipe xmas music throughout the office throughout the December
    months.)

    I guess the ability to turn off the speakers at each remote location makes
    the system a bit pointless now to send announcements, but again, I'd rather
    not try to hack into the system just to feed my own input just to my
    office.

    I was hoping that there was something simple I could do to get what I
    wanted. It doesn't sound like there is.

    James
     
  13. James

    James Guest

    One of the agreements I made before I was allowed to hook up the radio to
    the system was that there were to be no running wires in the storage room
    and that the entire radio system must be contained within the outlet box,
    with the box remaining shut at all times. Claimed it was a liability to
    have the wires running (which I can see) and to actually have the outlet
    box open (which I can't really believe to be true).

    Luckily the box has enough space inside to house the small radio, but I'm
    definitely not working with a lot of room.

    James
     
  14. I read in sci.electronics.design that James
    Well, you had a lot of sophisticated replies, but AIUI, nothing that
    works for you. I can see two solutions:

    1. Mount an IR sensor on the outside of the cupboard and use a remote
    unit like a TV control. You could build all this yourself. The IR
    receiver would switch the radio on by means of a relay or a FET.

    2. Buy a short-range radio transmitter and matching receiver, the
    receiver being configured for very low current consumption when idling.
    You would need to add a relay or FET to do the on/off switching, as for
    option 1.
     
  15. James

    James Guest

    Thanks John,

    Any thoughts as to where I can find a receiver like this?

    James
     
  16. I read in sci.electronics.design that James
    Well, you are posting from GMT -0500, but I still don't know where you
    are, even if I guess USA. There are a lot of Merkans here who can better
    advise you about sources.
     
  17. Rich Grise

    Rich Grise Guest

    The IR receiver out of a TV - or the circuit, copied - can turn the radio
    on and off, but you'd need either line-of-sight or the ability to set
    up mirrors for the IR.

    Good Luck!
    Rich
     
  18. Rich Grise

    Rich Grise Guest

    Piggyback a control signal on your speaker lead(s).

    Cheers!
    Rich
     
  19. Rich Grise

    Rich Grise Guest

    If it is a PA system, and each speaker has its own transformer, and the
    junction box just has a bunch of branches, then just move the radio to your
    office and connect its output to the primary of your speaker.

    That only works if it's a typical 70.7 volt PA system, where all the
    speaker transformer primaries are in parallel.

    Good Luck!
    Rich
     
  20. If you have line-of-sight contact, hitting photocells with a laser pointer
    is easier. I once designed a circuit (for "Q&A" in Popular Electronics)
    that had two CdS photocells. Hit one to turn on and the other to turn off.
    They formed a voltage divider driving a 555 configured as a Schmitt trigger.
     
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