USB to 4.5DC power adapter?

[DeathOnSight]

Hi all,

I would like to know if this is possible?
Basically i have a device that says it requires 4.5DC
It is also battery powered,(AAA 1.5v x2) which gives it sufficient power.

Would i be able to get an adapter to power this device over usb,or possibly create my own?(i know usb doesnt have much power,but maybe over like 4 ports?)

Thanks

 

[nand]

USB is 5V DC.
But what is it you want to power? 1.5 x 2 = 3V; doesn't seem like it would suffice if the device needs 4.5V.

 

[DeathOnSight]

USB is 5V DC.
But what is it you want to power? 1.5 x 2 = 3V; doesn't seem like it would suffice if the device needs 4.5V.

Oh snap i didnt know that.
its one of those Chinese frequency transmitters that plugs into the secondary audio port

works with wireless headphones.

The batteries power it though,so iom guessing it doesnt need alot of power?

Thanks

 

[sajunky]

The batteries power it though,so iom guessing it doesnt need alot of power?

Correct, probably similiar power to Bluetooth devices. Put genaral porpose silicon diode in series with (+). It opens at 05-0.6V, it will drop USB voltage to required 4.5V.

 

[Pada]

Also take note that the maximum current that you can draw from an USB 2 port is 0.5A. So just make sure that the device is less than say 2.5W.
USB 3 should be able to give you more power though.

If you need to drop the voltage to 4.5V or lower, then that diode trick like sajunky mentioned should work just fine. It would drop about 0.7V I think.

 

[sajunky]

If you need to drop the voltage to 4.5V or lower, then that diode trick like sajunky mentioned should work just fine. It would drop about 0.7V I think.

Of course, I know these things. It is expected under typical working conditions 10-100mA. However my verbose concern was to not allow overvoltage, when there is virtually no load from device. It could destructive and we don't know maximum limits. It is why my focus was on the opening voltage barrier instead.