While most appliances that run off of internal batteries also include a socket for an wall adapter, this is not always the case. Just because there is no hole to plug one in doesn't necessarily mean that you cannot use one.
 
  The type we are considering in this discussion are plug-in wall adapter that output a DC voltage (not AC transformers). This would be stated on the
nameplate.
 
  The first major consideration is voltage. This needs to be matched to the needs of the equipment. However, what you provide may also need to be well
regulated for several reasons as the manufacturer may have saved on the cost of the circuitry by assuming the use of batteries:
 
* The maximum voltage supplied by a battery is well defined. For example,4 AA cells provide just over 6 V when new. The design of the device may assume that this voltage is never exceeded and include no internal regulator. Overheating or failure may result immediately or down the road with a wall adapter which supplies more voltage than its nameplate rating (as most do
especially when lightly loaded).
 
* Most wall adapters do not include much filtering. With audio equipment,this may mean that there will be unacceptable levels of hum if used direct.There are exceptions. However, there is no way of telling without actually testing the adapter under load.
 
* The load on the power source (batteries or adapter) may vary quite a bit depending on what the device is doing. Fresh batteries can provide quite a bit of current without their voltage drooping that much. This is not always the case with wall adapters and the performance of the equipment may suffer. 
Dell LCD R0423 AC Adapter(Dell LCD R0423 AC Adapter )
Apple A1021 AC Adapter(A1021 AC Adapter )
Compaq 338136-001 AC Adapter(DC18.5V 3.5A )
Dell XD802 AC Adapter(DC19.5V 3.34A )
HP Pavilion DV6700 AC Adapter(AC100-240V)
Acer Aspire 5570-2947 AC Adapter(AC100-240V 50-60Hz)
Gateway PA-1650-01 AC Adapter(AC100-240V )
IBM Lenovo ThinkPad R60 AC Adapter(AC100-240V )
Compaq 402018-001 AC Adapter(DC18.5V 3.5A )
Gateway API3AD03 AC Adapter(DC19V 3.42A )
HP 324816-002 AC Adapter(AC100-240V )
HP 384019-002 AC Adapter(AC100-240V)
Dell PA-12 AC Adapter(AC100-240V)
Dell Latitude D620 AC Adapter(AC100-240V)
Toshiba PA3467U-1ACA AC Adapter(AC100-240V )
Dell AD-4214N LCD AC Adapter(AC100-240V)
Dell NADP-90KB AC Adapter(DC19.5V 4.62A )
Acer AL1714 LCD adapter(AC100-240V)
Universal 70W AC Adapter with 9 tips(AC100-240V)
Universal 90W AC Adapter 9 Tips(AC100-240V)
Liteon PA-1900-05 AC Adapter(AC100-240V)
Toshiba PA3165U-1ACA AC Adapter 90W(AC100-240V )
Dell PA-1900-05D AC Adapter(AC100-240V )
Dell PA-9 AC Adapter(DC20V 4.5A)
Dell Inspiron 1200 AC Adapter(DC19V 3.16A )
Dell Latitude 120L AC Adapter(AC100-240V)
Dell LCD PA-9 AC Adapter(AC100-240V)
Dell CF719 AC Adapter(AC100-240V)
Dell TD230 AC Adapter(DC19V 3.16A )
Dell Inspiron B120 AC Adapter((worldwide use) )
Dell 310-6499 AC Adapter(AC100-240V)
Toshiba K000040330 Adapter(100-240V, 50-60Hz )
Acer PA-1151-03 AC Adapter(AC100-240V )
Toshiba PA3290U-2ACA AC Adapter(AC100-240V)
Acer AL1714 LCD AC adapter(AC100-240V )
Compaq 239704-001 AC Adapter(AC100-240V )
Acer Aspire 5720Z AC Adapter(AC100-240V)
70W universal ac adapter(one adapter all power solution)
90W universal ac adapter(one adapter all power solution )
120W universal ac adapter(one adapter all power solution )
usadapter(high quality)
HP Pavilion DV8000 AC Adapter 90W(AC100-240V)
90W Universal AC Adapter(AC90W )
Gateway SADP-65KB B AC Adapter(AC100-240V)
Delta SADP-65KB AC Adapter(AC100-240V )
Toshiba Satellite X205-S9349 AC adapter(AC100-240V )
Acer PA-1161-06 AC Adapter 150W(AC100-240V)
Dell UltraSharp 2001FP AC Adapter(AC100-240V)
Apple ACG4 AC Adapter(AC100-240V )
Dell Inspiron 2200 AC Adapter(AC100-240V)
Compaq DC359A AC Adapter(AC100-240V)
HP Compaq NX9010 AC Adapter(AC100-240V (worldwide use) )
HP Compaq Business Notebook nx6310 AC Adapter(AC100-240V)
Asus G1S AC Adapter 19V 3.42A(AC100-240V (worldwide use) )