Posted by sparky on August 18, 2005, 12:52 am
I need to turn on a receptacle by remote(25 feet) and the reptacle can
NOT be used as a source of power for the relay. A battery powered relay
and a battery powered remote. Seen one anywhere ?
Posted by Scott Willing on August 19, 2005, 5:52 pm
Yes and no.
How handy are you?
I recently bought a couple of 12V remote-controlled relays intended
for turning on car lights (mainly to avoid the necessity of running
wires through the firewall and mounting a switch, but they have a
range of 250 feet).
Litelink, by Cooper Automotive, bought at Princess Auto.
One of these could be hooked up without internal modifications to a
small 12V gel cel (tricklecharged whenever the outlet was live, e.g.),
and its relay closure (rated 40A at 14VDC, BTW) used to engage an
external relay with specs suitable for switching the AC.
The quiescent power requirements of the receiver are minimal, and the
remote is the size of a matchbook.
Or if you have the skills and time on your hands... the internal
receiver circuit is actually powered from a TL05 5V regulator, so you
could replace the on-board relay with a 5V coil / 120VAC 15A unit to
control the outlet and probably run the thing from 4 AA's. (Again,
perhaps trickle-charged whenever the outlet was powered.)
If you're really ambitious you could try an arrangement that could
store enough energy (in a good-sized capacitor, e.g.) when the outlet
is powered - perhaps even topped up by stealing a bit from the search
mode pulses - to keep the remote receiver powered up and operate the
relay without the need for batteries at all. Trickier, admittedly,
dependent on duty cycle, dependent on whether the inverter is often
powered down completely... and whether the tinkerer has enough time to
do more than idly suggest such madness on a lunch break. :-)
Posted by Scott Willing on August 19, 2005, 6:05 pm
On Fri, 19 Aug 2005 12:52:53 -0500, Scott Willing
[snip blah blah blah]
Say, if you're off-grid, perhaps you'd have the option of running this
thing directly off your primary battery? Don't suppose you're at 12V
primary? Don't suppose you could either (a) put the receiver and relay
in the power room and control the feed to the outlet from there
(probably a bunch of other stuff on that circuit, right?) or (b) get
12V from the power room to some convenient location near the outlet?
If you have 12V in the right place already, all you'd need to do is
replace the relay in this thing with a suitably-rated one (a
pin-compatible part could probably be found with 120VAC contacts ) and
then isolate the contacts from the 12V circuit and connect them to the
Truth is the contacts in a 40A 14VDC relay would probably be more than
fine for 15A @ 120VAC... but officially I'm not suggesting that you
try that, nudge nudge, wink, wink.
In all seriousness, unless you know enough to get in there and safely
isolate the contacts from the 12V circuit completely, all nudging
aside: don't do it.
Posted by sparky on August 20, 2005, 1:11 am
Thanks Scott ! Just want to get the inverter out of sense to open the
garage door opener. Wife really epected that inverters should be
designed for this in the first place. I have little time as I started a
new job building the most expensive Barometer in the world and ......
Anyway since I only want to switch a 11 watt ac light on I was hoping
for off the shelf / turnkey. How about a post with light switch by the
Posted by Vaughn on August 22, 2005, 5:58 pm
Odd that you mention garage door opener...that is exactly what I was
thinking about. You can buy the clickers and receivers at any Home Depot and
there is no law that says you must use them on your garage door. The receivers
are usually fed with a wall wart, but I would be surprised if you could not make
one run on 12VDC. All you would need is a dedicated gell cell battery to run
the receiver when the inverter was in search and some sort of charger.