trying to make a wireless door chime trigger a relay...

J

Jim

Guest
I have looked all over for a short distance, remote/radio-controlled
switch to trigger a relay with a momentary switch.

I could use an existing home-use device with the battery powered
transmitter and the AC powered receiver, but it is not a momentary
switch, you must make contact once to turn ON the device and again to
turn it OFF.

A cheap wireless Door Chime seems to fit the bill, you press the
button ONCE and the thing chimes for a second or so and then resets,
ready for the next push of a button.

However- Now that I have taken apart the wireless door chime, the only
place I can think to tap into it is the wires that go to the little
speaker. Ideally, I would like to remove the little speaker and just
take the 2 wires, attach them to a relay, but I don't know what
voltage would trigger this. I've tried a 12vdc relay I had and it did
nothing. (The wireless door chime itself is 110vAC-powered... the
button/transmitter is the "wireless" part)

is there another part of this cheapo device I should be looking at to
tap into instead? my electronics knowledge is pretty limited....

the email address is valid until it starts getting spam.....

Jim
 
First off , get out the multimeter and check your voltage across the speaker
wires. There most likely won't be enough current in it to operate a relay
directly even if you get the needed voltage. From here you could build a simple
transistrorswitch to trigger the relay. Of course you would have to do the math
to get the needed specs, but IMO it would probably be the simplest method to
achieve your goal.


"Jim" <usenet@1500main.com> wrote in message
news:5f4cb03a.0402231447.42cf5a29@posting.google.com...
: I have looked all over for a short distance, remote/radio-controlled
: switch to trigger a relay with a momentary switch.
:
: I could use an existing home-use device with the battery powered
: transmitter and the AC powered receiver, but it is not a momentary
: switch, you must make contact once to turn ON the device and again to
: turn it OFF.
:
: A cheap wireless Door Chime seems to fit the bill, you press the
: button ONCE and the thing chimes for a second or so and then resets,
: ready for the next push of a button.
:
: However- Now that I have taken apart the wireless door chime, the only
: place I can think to tap into it is the wires that go to the little
: speaker. Ideally, I would like to remove the little speaker and just
: take the 2 wires, attach them to a relay, but I don't know what
: voltage would trigger this. I've tried a 12vdc relay I had and it did
: nothing. (The wireless door chime itself is 110vAC-powered... the
: button/transmitter is the "wireless" part)
:
: is there another part of this cheapo device I should be looking at to
: tap into instead? my electronics knowledge is pretty limited....
:
: the email address is valid until it starts getting spam.....
:
: Jim
 
On 23 Feb 2004 14:47:58 -0800, usenet@1500main.com (Jim) wrote:

I have looked all over for a short distance, remote/radio-controlled
switch to trigger a relay with a momentary switch.

I could use an existing home-use device with the battery powered
transmitter and the AC powered receiver, but it is not a momentary
switch, you must make contact once to turn ON the device and again to
turn it OFF.

A cheap wireless Door Chime seems to fit the bill, you press the
button ONCE and the thing chimes for a second or so and then resets,
ready for the next push of a button.

However- Now that I have taken apart the wireless door chime, the only
place I can think to tap into it is the wires that go to the little
speaker. Ideally, I would like to remove the little speaker and just
take the 2 wires, attach them to a relay, but I don't know what
voltage would trigger this. I've tried a 12vdc relay I had and it did
nothing. (The wireless door chime itself is 110vAC-powered... the
button/transmitter is the "wireless" part)

is there another part of this cheapo device I should be looking at to
tap into instead? my electronics knowledge is pretty limited....

the email address is valid until it starts getting spam.....

Jim
Click to expand...
You might use an NPN transistor as the switch. A diode going to
the transistor base from one sife of the speaker wire with the
emitter connected to the other wire may allow the transistor to
work.
 
On 23 Feb 2004 14:47:58 -0800, usenet@1500main.com (Jim) wrote:

I have looked all over for a short distance, remote/radio-controlled
switch to trigger a relay with a momentary switch.

I could use an existing home-use device with the battery powered
transmitter and the AC powered receiver, but it is not a momentary
switch, you must make contact once to turn ON the device and again to
turn it OFF.

A cheap wireless Door Chime seems to fit the bill, you press the
button ONCE and the thing chimes for a second or so and then resets,
ready for the next push of a button.

However- Now that I have taken apart the wireless door chime, the only
place I can think to tap into it is the wires that go to the little
speaker. Ideally, I would like to remove the little speaker and just
take the 2 wires, attach them to a relay, but I don't know what
voltage would trigger this. I've tried a 12vdc relay I had and it did
nothing. (The wireless door chime itself is 110vAC-powered... the
button/transmitter is the "wireless" part)

is there another part of this cheapo device I should be looking at to
tap into instead? my electronics knowledge is pretty limited....
Click to expand...
---
Do you have a multimeter?

--
John Fields
 
On 23 Feb 2004 14:47:58 -0800, usenet@1500main.com (Jim) wrote:

I have looked all over for a short distance, remote/radio-controlled
switch to trigger a relay with a momentary switch.

I could use an existing home-use device with the battery powered
transmitter and the AC powered receiver, but it is not a momentary
switch, you must make contact once to turn ON the device and again to
turn it OFF.

A cheap wireless Door Chime seems to fit the bill, you press the
button ONCE and the thing chimes for a second or so and then resets,
ready for the next push of a button.

However- Now that I have taken apart the wireless door chime, the only
place I can think to tap into it is the wires that go to the little
speaker. Ideally, I would like to remove the little speaker and just
take the 2 wires, attach them to a relay, but I don't know what
voltage would trigger this. I've tried a 12vdc relay I had and it did
nothing. (The wireless door chime itself is 110vAC-powered... the
button/transmitter is the "wireless" part)

is there another part of this cheapo device I should be looking at to
tap into instead? my electronics knowledge is pretty limited....
Click to expand...
---
The chime sound you're getting from the speaker is AC, so there's no way
you could just hook a DC relay across the wires and have it be energized
by the AC signal.

If you had enough power available out of those two wires it's
conceivable that you could rectify the AC, smooth it, and use it to
drive a relay directly, but it's not likely that you have enough power
available.

In any case, it would be informative to know what's going on there, so
if you could measure the DC resistance of the speaker when it's not
hooked up to the wires and then the AC voltage of the signal across it
when it's chiming, that would be the place to start, I think.

It would also be nice to know what the DC supply voltage used to run the
receiver is, and if one side of the speaker is referred to either the
supply voltage or to "ground", the supply return.

It would also be VERY nice to know if the circuitry is isolated from the
mains, since that could very well keep an assumption from killing you!

What I have in mind is rectifying and smoothing the signal on the
speaker wires and using the resulting DC to turn on a transistor which
will in turn turn on a relay using the receiver's DC supply, and since
you indicated that you do have a multimeter, we'll need for you to make
the measurements outlined above and to post what you find before we can
proceed.

When you make the measurements to determine whether the speaker wires
are isolated from the mains, what you'll need to do is to completely
disconnect the receiver from the AC mains and then measure the
resistance from both sides of the speaker to both sides (and ground, if
it's 3 wires) of the mains and post what you find. If it's completely
isolated you should get a very high resistance from either of the
speaker terminals to either mains hot or mains neutral. If it's not
high, or if you get a low resistance between the speaker and ground or
the speaker and neutral, then since your electronics knowledge is
"pretty limited" it may not be a good idea to go any farther unless you
get an isolation transformer for safety's sake.

--
John Fields
 
John Fields <jfields@austininstruments.com> wrote in message news:
... If it's not
high, or if you get a low resistance between the speaker and ground or
the speaker and neutral, then since your electronics knowledge is
"pretty limited" it may not be a good idea to go any farther unless you
get an isolation transformer for safety's sake.
Click to expand...


thanks for your help John, this is going to be a bit more difficult
and/or dangerous than I imagined.

I will take your instructions and play with it just to learn, but I
think this has gone beyond my "limited" skill-set.

In the meantime- since I posted this message, I found an existing
circuit available in either kit form or completed. It does EXACTLY
what I need it to do and it is in a small package ready to go
http://www.rentron.com/PicBasic/RemoteControl.htm

a remote control with either latching or momentary control.

hurray!
 
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