Relay to control appliances connected to pc

Click For Summary

Discussion Overview

The discussion revolves around the design and implementation of a relay system to control multiple appliances connected to a PC, particularly focusing on the wiring and functionality of the relay in relation to the PC's power state. The conversation includes practical solutions, alternative methods, and humorous interjections.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant describes a relay wiring setup intended to control lights and speakers based on the PC's power state, questioning whether the high coil resistance would allow sufficient current to flow to the PC.
  • Another participant suggests a simpler solution of using a power bar with a master switch to control all devices simultaneously.
  • A different participant mentions the availability of USB-connected power strips that can be controlled via a relay, proposing a DIY approach for a more cost-effective solution.
  • Several posts include light-hearted banter about the capabilities of Google and humorous references to unrelated topics, such as teaching a snake to tap-dance.
  • One participant notes the existence of power strips that automatically activate other outlets when current is detected in a designated "trigger" outlet, mentioning adjustable sensitivity settings.

Areas of Agreement / Disagreement

Participants express a range of opinions on the best method to control appliances, with some favoring the relay approach and others advocating for simpler solutions like power strips. The discussion includes both technical inquiries and humorous exchanges, indicating a lack of consensus on the optimal solution.

Contextual Notes

The discussion includes various assumptions about electrical components and their interactions, particularly regarding the relay's functionality and the implications of using high resistance in the coil. There are also references to specific products and DIY solutions that may depend on individual preferences and requirements.

Who May Find This Useful

Individuals interested in home automation, electrical engineering, or DIY electronics projects may find the discussion relevant, particularly those looking for solutions to control multiple devices based on a PC's power state.

bwana
Messages
82
Reaction score
2
when my pc shuts off, i want to shut off a bunch of other things too-speakers, light, monitor.

to do this i need a relay but am a little perplexed on the correct wiring.
(Please ignore the periods. they are necessary to make this drawing look right but have no meaning)

Voltage_____|
. . . . . . . . . .|
1___| . . . . . |
. . . .| . . . . . |
. . .coil = ). . |(
. . . .| . . A. . .B
2___| . . .|
. . . . . . . |
. . . . . . .R1 (lights, speakers)
. . . . . . . |
Neutral__|

When the coil is energized(current from 1 to 2), the switch moves from B to A.

Is it workable to also connect Voltage to 1, then to connect 2 to the hot leg of the pc power cord and then the neutral leg of the pc power cord to neutral? It would look like this:

Voltage_____|
| . . . . . . . . .|
1___| . . . . . |
. . . .| . . . . . |
. . .coil = ). . |(
. . . .| . . A. . .B
2___| . . .|
|. . . . . . .|
PC. . . . . R1 (lights, speakers)
| . . . . . . .|
Neutral___|

The idea is to get current to flow through the coil when the pc is on. This allows current to flow through R1. And when the pc is off, there is current through R1.

The resistance through the coil is 2 kOhms and this is an A/C relay rated at 10 amps for 120 volts. or is this stupid because insufficient current will flow to the pc because the coil resistance is so high?
 
Engineering news on Phys.org
Wouldn't it be a lot easier to just plug everything into a power bar and flip the master switch?
By the bye, on any of my non-portable Macs the shutdown automatically kills power to the monitor.
 
You can buy a USB connected power stip from from ecostrip for a ridiculous amount of money (thinkgeek used to do a cheap one)
Or if you google usb controlled power strip there are dozens of DIY versions - you just switch the 110/230V live input line with a 5v relay.
 
tnx.
google found this for me:
http://www.instructables.com/id/SC9F1YAFJKGWVP3/

is there anything google can't do?
 
Last edited by a moderator:
bwana said:
is there anything google can't do?

I'm pretty sure that it can't teach a snake to tap-dance... but who can? :wink:
 
Danger said:
I'm pretty sure that it can't teach a snake to tap-dance... but who can? :wink:

Mel Brooks !

spacemag5.jpg
 
mgb_phys said:
Mel Brooks !

Damn, but you're quick.
Unfortunately, you are mistaken. Since that critter has legs, it is not a snake.
Cudos for your response, though. :approve:
 
There are power strips made that automatically turn on the rest of the outlets when current is detected in the "trigger" outlet. There is a threshold adjustment knob to set the sensitivity of the trigger outlet. They work with about everything once the adjustment is set.

I forgot the company, but they are on the same page as the Kill-A-Watt meter on Amazon, which I can't get to right now.
 

Similar threads

Multiple signals controlling relay
  • · Replies 7 ·
Replies
7
Views
1K
Solving Power Delivery Issues in a 5V Series Circuit with a 1.5V Rated Relay
  • · Replies 12 ·
Replies
12
Views
3K
Motorcycle starter safety circuit
  • · Replies 11 ·
Replies
11
Views
5K
Controlling line power with a 6V circuit using a relay.
  • · Replies 4 ·
Replies
4
Views
3K
Relay and Capacitor circuit - blinking LED
  • · Replies 26 ·
Replies
26
Views
7K
How to calculate magnetic braking force?
  • · Replies 14 ·
Replies
14
Views
6K
Relays, transformers, actuators and a differential controller
  • · Replies 1 ·
Replies
1
Views
3K
Relays - Controlling voltage flowing for heater elements to maintain temperature
  • · Replies 5 ·
Replies
5
Views
3K
Is My Thyristor Gate Driver Circuit Malfunctioning Due to Component Issues?
  • · Replies 12 ·
Replies
12
Views
3K
Is there a way to keep an LED turned on even when the power source is off?
  • · Replies 2 ·
Replies
2
Views
2K