84Views3Replies

Author Options:

Circuit/relay that senses when ac appliance is in use Answered

Hello all,
I am attempting to add some ambient lighting to my home theater system.  I would like the lighting to activate whenever the tv or receiver are switched on (these units are always on together).

I am a novice tinkerer, who is capable of soldering and simple circuit design, but I am having trouble finding a way to activate the lights without opening (read: voiding the warranty) my receiver or television.

What would be the easiest way to accomplish this?

A few of my unformed ideas would be:
     -A relay that could sense when a/c power is being consumed (aka, receiver/tv being switched on)
     -Would some sort of hall effect sensor accomplish the above?

I'm just not really sure how to tackle this one, any suggestions are appreciated.  My project priorities are (in order): 1) ease/simplicity of design, 2) the smaller the component size the better, 3) cost

---EDIT---

I'm not sure if this helps, but this item came to mind, a Small Engine Hour Meter http://www.buy.com/pr/product.aspx?sku=226358043&sellerid=24561471  This item can sense the current to the spark plugs without a physical wire connection. (induction?)  I know that item is intended for dc use, but could one be adapted to AC?  Or does anyone know if the relatively low dc voltage signal to my speakers could be used to activate a product like this?  TIA

Comments

The forums are retiring in 2021 and are now closed for new topics and comments.
0
crob09
crob09

9 years ago

Do you think something like Arduino could be used for a project like this?
Also I think Phidgets may have something that will work.

Just a thought.

http://www.whatisacnc.com

0
Jayefuu
Jayefuu

9 years ago

How new's your TV? Newish ones have USB sockets on them, if yours has one you could buy one of those off the shelf power cables for PCs that you plug into the PCs USB and when the PC turns off the USB does too and so it turns off all of your peripherals for you.

You can also buy current sensing relays. Or I quite like Goodhart's suggestion of monitoring a status LED somewhere. Or you could use a current clamp.

0
Goodhart
Goodhart

9 years ago

On your first "idea": A relay that could sense when a/c power is being consumed (aka, receiver/tv being switched on) that may work with the receiver side (unless they are powered by the same cord) but not the tv (most tv's are "always on".
Although I am not so sure about the newer flat screens...

A small light sensor (CDS cell?) could be taped to the lower corner of the screen signalling when the screen is "lit". 

On you "EDIT":  yes, induction works for sensing voltage/amperage, but is normally reserved for higher voltages (like what would be on the INSIDE of your tv :-).