Have you tried http://www.farnell.com/distributors/philippines.htm and http://philippines.rs-online.com/web/?
Your probably referring to this H bridge diagram, http://s.eeweb.com/members/von_wong/answers/1335122304-h-bridge.gif Or possibly a simple H bridge chip, http://www.elektroda.pl/rtvforum/files-rtvforum/ckt_mtr_1826.jpg
can i charge panasonic sla 6v battery (Panasonic LC-RB064P) by my 7.5v 500mA ac to dc adaptor?take note that the battery is 4ah and my charger has only 500mA....
If your following the first link I gave you then, tip 41, should be fine. But looking at the data sheet, its made for high voltage applications. Kinda overkill for your project. You may just want to get some 2n3904 or 2n3906 NPN transistors from RadioShack, or simply a H-bridge DC Driver IC.
The 2n5551 is fine, the maximum voltage it can handle is 160 volts, so 7 volts should be nothing to it.
Double check your wiring, and make sure only one side of the H bridge is on at a time.
That circuit will not work as it stands and may damage the lower transistor because there is no resistor to limit the base current. Put a 100 ohm resistor in series with the base of the upper transistor, and a 470 ohm resistor in series with the base of the lower transistor. Increase both the power supply voltage and the drive voltage to 5V. That will give you about 3V or 3.5V across the load.