SOLVED 12v Into 6v OK ?

[setotitan]

Hey all I guess this isn't exactly the right forum for this question, however I figure it's premise should apply.. anyway. Someone gave me a set of these baby monitors, no idea where they got them from, brand new but a couple years old. Anyways everything works OK except one of the power cords is 6vDC and appears to be busted. We're kinda strapped right now, so I'm trying to make something work that I found around the house. I have this 12vDC adapter that was to an old hobby helicopter charger. Anyways I plugged it up, seems to work fine, nothings running hot or anything. However before I chalk this up in the win coulmn I thought I'd ask if this is long term solution. I'd hate for it to burst into flames and catch my newborn daughter's crib on fire, ya know. Thoughts?

 

[tinymouse2]

Overvolting! Just add a resistor to drop 6V?

 

[Bobnova]

I'm surprised it didn't die on powerup, 2x the volts is generally fatal.

 

[setotitan]

Would an external resistor run the same cost as buying a 6v power plug? Or are you talking about cracking open the plug base and soldering a resistor into it?

 

[tinymouse2]

Hmm I might have been implying just cutting a few wires and botching in a resistor and seeing that it's a baby monitor maybe that idea wasn't very good...

Check to see how much a 6V plug is, if it's to expensive just buy a resistor and a load of duct tape to ensure no-one can touch the exposed wire?

 

[TempliNocturnus]

If it works with no problems now, you should be fine. Many devices that run on DC contain a component called a zener diode in the circuit where it receives the power. Zener diodes essentially behaves as a variable resistor, but only when a certain voltage is applied to it. It does have a maximum resistance that it will will reach, and a breakdown voltage.

In your case, the zener voltage in your hardware is probably 6v and it's max impedance is 6 Ohms or more. As long as your device does not exceed the zener's maximum power handling, you should have no problems. However, if you apply 12v to the device for a long period of time, it could, in theory, "burn in" that resistance in that zener and if you do switch to a lower output DC adapter, you could have issues due to under-powering.

You can buy a power adapter fairly cheap from many places. I bought one from Radioshack awhile ago that has a switch on it allowing me to vary the voltage between several different voltages between 1.5v - 3.3v - 6v -12v. It was only like $15. Just solder on the connector from one that fits if the one you buy doesn't fit.

 

[setotitan]

All excellent information, thanks guys I knew I'd get my answer here.

 

[Duner]

That's great information.

My 3G router has a label on the back of it that says 9-24V input and it comes with a 12V supply. I was wondering how it could handle such a wide range of DC volts.

If it works with no problems now, you should be fine. Many devices that run on DC contain a component called a zener diode in the circuit where it receives the power. Zener diodes essentially behaves as a variable resistor, but only when a certain voltage is applied to it. It does have a maximum resistance that it will will reach, and a breakdown voltage.

 

[Bobnova]

Your router has a voltage regulator inside, the router guts themselves likely run at 3.3v or 5v, and they use a nice lossy regulator so you need a few volts over that for the regulator to work correctly.