Hello everybody. I'm working on a project to reset my router using an RF module controlled by a microcontroller.

PNP TRANSISTOR (disregard the position of the 'c', I put it to close the the base)

I have a transistor connected to my router/microcontoller like so...

now when I finalize the circuit (connect battery to power rail which is connected to the microcontroller) the router remains off and I am able to hear a very faint (high frequency) screeching noise. Why is this not working?

I am able using the transistor/microcontroller to successfully switch on and off LEDs, but not my router.

Here is a verbal description of how my transistor is set up just incase I made an error there.
Connected to my base is a low coming from my microcontroller
Connected to my emitter is my source voltage coming from wall outlet and pin connected to high from battery
Connected to collector is my router.

All help is appreciated

 

Why do you want to reset your router?

 

Why do you want to reset your router?

every so often the router speed goes really low until you manually reset it. The router is in an upstairs bedroom and it becomes very tedious to go upstairs to reset it every hour. Yes I know I can just buy a new one, but I'd like to learn a thing or two from this project.

 

How much voltage and current does the router require?

 

How much voltage and current does the router require?

12VDC
1A

As far as I know, BJTs don't have a voltage drop, right?

 

The power supply ground, the μC ground, and the router ground all have to be common. Are they?
Are you sure the router needs a high level for reset?
Is the power supply voltage providing the proper voltage level to the router? If it's too high, it can damage your router.

 

I think he is trying to switch the power supply with a PNP transistor.

 

I think he is trying to switch the power supply with a PNP transistor.

That makes more sense than what I was thinking.
So just the μC and the router grounds have to be common.
I would use a p-channel MOSFET for the switch.
PNP or PMOS, he will still need a level-shifter of some sort to switch 12V from a μC.

 

That makes more sense than what I was thinking.
So just the μC and the router grounds have to be common.
I would use a p-channel MOSFET for the switch.
PNP or PMOS, he will still need a level-shifter of some sort to switch 12V from a μC.

Ohhhhh, can you please explain why the router and μC ground have to be on the same rail?
I didn't have it set up like that, didn't think it made a difference.
Will test tomorrow morning when the internet is not being used.
Thank you .

and isn't my power supply ground the same as my router ground? or am I missing something here.
I am using two sources for EMF. A battery and a Netgear wall-wart.

 

As far as I know, BJTs don't have a voltage drop, right?

Oh yes they do. Find datasheet for your transistor and look
at Vce (Voltage Collector to Emmiter).

You will possibly be better of using a transistor to switch
a relay, which in turn will switch your power supply ON/OFF.

Look HERE for some basic transistor used as a switch schemes.
Note: on that page, Hfe for the transistor is used in the calculation
for base current. I believe the general consensus is to use Ib=Ic/10
when using a transistor as a switch.

If you intend to use a MOSFET instead of a transistor, which would
possibly be a better idea with a micro controller, and need help just
ask.

 

If I understand what you are trying to do, you need to use one of the options in the attachment. Note that the MOSFET version is much more efficient (draws less current) and has less voltage drop.

 

If your router is just slowing down, can't you just address it through your browser and command a reset? That's what I do when mine gets too slow.

 

Hello again,
I found the source of my problem which was the resistor connected in between the microcontroller and the base of the transistor. When I remove the resistor, the router turns on.
However, after about 10 seconds, the microcontroller gets very hot.
I was using a 1k resistor, will using smaller resistance solve this problem?
Why is this happening?

Thank you.

 

Hello again,
I found the source of my problem which was the resistor connected in between the microcontroller and the base of the transistor. When I remove the resistor, the router turns on.
However, after about 10 seconds, the microcontroller gets very hot.
I was using a 1k resistor, will using smaller resistance solve this problem?
Why is this happening?

Thank you.

Did you use one of the circuits I posted? If not, then that's what's wrong.
Post your schematic. Please make it a little cleaner than the first one. Include all parts and connections.