IC or transistor to act as relay switch

Need this to act as a switch to turn a computer on/off. The wires will be connected to the motherboard on/off headers. These headers simply need to be shorted momentarily, and the PC would then turn on.

 

Right now, I am using a relay switch to do this, but I believe an IC or transistor would be able to do it too. Actual relay switches are expensive compared it transistor.

 

The current flowing through the transistor would be very small, and thus an actual relay switch is simply a waste.

 

How would I go about using transistors? I have 8 computers that I want to be able to control using Netduino, would it better to get an IC chip instead?

 

I don't think I need resistors, as I am simply completing the circuit (just like there is no resister in a PC on/off switch on the case).

 

Since the transistor should normally be OFF, I believe I need a NPN type. The transistor needs to be OFF when there is no current.

How would I connect the wires? Would appreciate it if you can link me a sample transistor, and a short code snippet.

 

Sorry, I am new to IC and transistors, and don't really know how to make them work.

I would recommend getting a bag of pnp and npn transistors, a bread board and following some tutorials before you start trying to interface with pc hardware. Out of interest why are you trying to replicate switch functionality when you could use wake on lan to do the same thing?

I would recommend getting a bag of pnp and npn transistors, a bread board and following some tutorials before you start trying to interface with pc hardware. Out of interest why are you trying to replicate switch functionality when you could use wake on lan to do the same thing?

Only reason I want this is b/c what if the PC got a hard freeze, and need a hard reset.

WOL can only wake up a PC when it is OFF. In the case that the PC freezes, it would still be considered ON.

Let me know if there are other easier way around this.

Only reason I want this is b/c what if the PC got a hard freeze, and need a hard reset.

WOL can only wake up a PC when it is OFF. In the case that the PC freezes, it would still be considered ON.

Let me know if there are other easier way around this.

 

Couldn't you hard reset your PC by holding the power button until it turns off, waiting 10 seconds, then turning it on again? Or do you need to automate this?

Couldn't you hard reset your PC by holding the power button until it turns off, waiting 10 seconds, then turning it on again? Or do you need to automate this?

I neede a way to do this when I am away from the PC.

Hi chungenhung,

I think this is an ideal application for an opto-isolator.

I did some experimentation a while ago and found one that uses a tiny amount of current to drive the LED.
Have a look at this wiki page for some ideas: http://wiki.netduino...rrent-load.ashx

I think in your case, you would just need the isolator without an extra power transistor.

Hope this helps - Paul