Passthru question

[Jules22871]

Why do some passthus have batteries in them? I thought the whole idea of a passthru was to run off the power from a USB port. Why do they need a battery in them? I have a passthru made by Nerf, well a couple of them actually, and there isn't a battery in them and they work. The ones we have learned to make ourselves dont' have batteries in them and they work fine. What is the point of having a battery in a passthru?

 

[SLDS181]

A usb port only has to put out .5 amps to meet the spec (without acting as a device, interfacing with the pc, and asking for more power) - not enough for your atomizer. Also, as the voltage can vary, including a battery will allow a more regulated voltage, so that its more consistent when being used. I should also point out that having an in-line battery prevents there being too much draw from the usb port, and potentially damaging the motherboard.

Without a battery, most people use their AC power with a 5-6vdc wall wart that will give 1.5 amps.

 

[Jules22871]

Thanks, that actually makes sense. I usually use my passthru with a kensington because I sit so far from my tower so I had no idea what the battery was for. Thanks for the explanation!

 

[Jim Davis]

My brother-in-law had one with a battery. He had nothing but trouble with it. I cut out the battery, and ran it direct to the USB. He's been a happy camper ever since.