Replacement ac adapters....do I need to match the specs of the original?

I've gone through two ac adapters on my J720 (both broke). I found a couple adapters at work that are relatively close to the specs of the Jornada's adapter, and I'm wondering if they're close enough to work or I need to match the original.

IIRC, the Jornada's adapter's specs are:
- Input: 100-240V, 1.5 A, 50-60Hz
- Output: 12V, 2.5A

The two adapters I found have these specs:

Adapter #1
- Input: 100-240V, 50/60Hz, 0.3A (max)
- Output: 5V, 2.1A

Adapter #2
- Input: 120V, 60Hz, 3VA
- Output: 5V, 200mA

Would either of these work with the Jornada?

Never mind - the plugs are too big.

. . . and the voltage is too small.

(You need a 12-volt adapter to charge the Jornada.)

Got it working today. I had a non-OEM adapter that had stopped working...turns out the issue was in the cord between the outlet and the brick. I thought the problem was with the brick itself. Replaced the cord with a spare from an old PC, and it's working again. It'll be nice to have my Jornada back!

For future reference, the voltage must match, the amperage can be equal or over, but shouldn't be too far under.

Thanks, C:Amie. I knew there was a formula; I just couldn't remember what it was.