Hi, I recently bought this Dynex DX-UC202 USB 2.0 PC card adapter for my old laptop (WinXP) with USB1.1 ports, but I have no information regarding the external 5VDC polarity (POSITIVE or NEGATIVE CENTER?). Note: I have a 5VDC adapter with switchable polarity and a connector that fits, but I can't use it since I don't know the polarity. I searched the web for this information but I did not find it.

Note: Not in the instruction manual. Does anyone know the polarity? Thank You in advance, John Paul 20.04.12 13:52. All I could find, by analogy, is the manual for a Belkin card.

'Note: The included power supply is not needed for bus-powered USB devices such as keyboards and mice, or self-powered USB devices such as hard drives, printers, etc. Bus-powered devices that draw large amounts of power directly from the USB bus, such as webcams and certain scanners, will require the use of the power supply.' On the specification page, theirs shows 'Center Plus' via an icon in the spec table. You can probably verify that, using an ohmmeter. The USB port has +5V and GND pins, and you should find continuity from GND to GND. There is little chance of that connector, being 'polarity protected'.

So be absolutely sure of your choice, before connecting. If they added a polarity protection diode, it could put the bus power too far out of spec (too much drop). Based on the dimensions shown in the Startech manual for their PCMCIA adapter, the barrel connector is an Adaptaplug 'H'. 3. Pokenet Game. 4mm OD, 1.3mm ID according to the Startech manual. But there's no reason they all have to be the same.

So that's just a hint, rather than a sure thing. If you were going to power via the Adaptaplug route, you'd go to Radioshack and use their wall display 'Adaptaplug octopus' to test the PCMCIA card connector before buying a plug. I was really surprised the Startech manual didn't mention polarity on theirs, as usually Startech is pretty good about details. There aren't many companies that give good tech specs. Paul Paul in Houston TX 20.04.12 15:49. Lipman wrote: >From: 'Paul in Houston TX' >>>wrote: >>>Hi, >>>I recently bought this Dynex DX-UC202 USB 2.0 PC card adapter >>>for my >>>old laptop (WinXP) with USB1.1 ports, but I have no information >>>regarding the >>>external 5VDC polarity (POSITIVE or NEGATIVE CENTER?). Note: I have >>>a 5VDC >>>adapter with switchable polarity and a connector that fits, but I >>>can't use it >>>since I don't know the polarity.

Apr 21, 2012 Dynex DX-UC202 USB 2.0 PCMCIA CardBus Adapter External 5VDC Polarity Showing 1-12 of 12 messages.

I searched the web for this >>>information but >>>I did not find it. Note: Not in the instruction manual. Tomb Raider Trainer on this page.

>>>>>>Does anyone know the polarity? >>>>>>Thank You in advance, John >>>>>and here: >>>>As I thought, but didn't post. >>Negative on the outside of a coaxial power connecter. >Not always.

Devices exist with both center plus and center minus. A number of the adaptaplug power supplies I've got, support reversal by rotating the plug 180 degrees. You have to be ready for anything. 'Over time, there has been a trend to de facto standardize with negative DC voltage on the barrel.

But barrel positive polarity is still occasionally seen, along with the continued usage of coaxial power connectors for low voltage AC power as well.' Somewhere, I read there was some standard, which suggests a label be affixed to each barrel power hole. Usually, they mold the polarity info, into the plastic, so you see 'black on black' and it's easy to miss. Montanari Jewelers on this page. None of the PCMCIA USBs I just looked at, had the molding. To further complicate matters, barrel powered devices exist, which can accept AC, unregulated DC, or regulated DC. The unregulated one can be a bit deceptive.

It consists of a transformer, bridge rectifier, and filter capacitor, for its power supply. This gives a DC level that varies with loading. On my label maker, it says '7 VDC' next to the barrel connector, but in fact, the power supply varies from around 7V (full load) to 10V (no load). If you plug in a 7VDC regulated adapter (which I tried), the device won't print. So in fact, the label maker wants 7V unregulated DC (varying from 7V on upwards, as a function of load). When the motor advances the label tape, the voltage drops. So really, you want documentation, before shopping for, or connecting a barrel connector, just to be sure you've covered the bases.