Greetings, I have a device which runs on 4 AA batteries that I'd like to power on automatically when my PC is on. I think the best way to do this is to use the +5V from the USB port to send a wireless (RF?) signal to the device to turn it on. The devices sit ~10 feet apart w/ no obstructions. Can somebody recommend what kinds of components and design I'll need for this? Thanks for your help.
IR link or Bluetooth technology or hack a wireless mouse or keyboard.
D from BC
Thanks, D from BC, but
1) I don't want to have a constant IR source. 2) Bluetooth is way overkill for a switch 3) This suggestion doesn't make sense.What I'm looking for is an RF transmitter operating from +5V and a receiver that will close a relay when it senses the RF. Something like this would be appropriate, but it operates from
12-15VDC:
Ok...maybe the wireless mouse idea sucks but it has the RF electronics.
D from BC
You shouldn't have to. Send one pulse pattern for "on" and another for "off", kinda like a TV remote. (If you decide on IR, that is.)
2) Bluetooth is way overkillHoly yikes! This won't do anything near what you claim to want. All you'd really need would be an oscillator, and a sort of crystal set and amplifier/detector/switch at the receiver. Try googling transmitter/receiver set or so.
Or, you could just use small wire and hide it.
Good Luck! Rich
Rich Grise wrote in news:pan.2007.06.15.21.26.15.63667 @example.net:
you'd
How about an IR remote control powered from a port and a receiver in the device. Or better, just walk a few feet and turn it on when you turn on the computer...
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Hack an RF remote control toy. Conceptually:
+6 ---[SCR]---[RelayContact]---[YourDevice]---Gnd | Toy ForwardToySteering===[RelayCoil]
When you operate the toy remote for "forward" it turns the SCR on, and conducts current through the normally closed relay contact and your device. It stays on until current is interrupted. When you operate the toy remote for steering, it energizes the relay, interrupting the current and turning the SCR and your device off.
If you need only "on control" (ie your device goes on or off when the PC goes on or off), then forget the SCR and just use the relay's normally open contact. The relay coil can be connected to replace either the steering or the drive motor.
Ed
Dan wrote in news:1181934327.528209.13380 @w5g2000hsg.googlegroups.com:
In the receiver, you will have a micro with a sleep mode. It will wake periodically to check for the presence of RF signal, and if present, decode, and if code=true, fully power device, if not go back to sleep. If awake and it fails to receive further codes, it goes back to sleep mode.
The transmitter will have a micro, that when powered initially sends a continuous stream of coded RF (so the receiver can find it), and after a while goes into an occasional pulse.
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