Modern SIM cards allow applications to be loaded when the SIM is in use by the subscriber. These applications communicate with the handset or a server using SIM application toolkit, which was initially specified by 3GPP in TS 11.14 (there is an identical ETSI specification with different numbering).
(Redirected from Voltage follower) A buffer amplifier (sometimes simply called a buffer) is one that provides electrical impedance transformation from one circuit to another. Two main types of buffer exist: the voltage buffer and the current buffer.
In an NPN transistor, current flows from the collector to the emitter. In a PNP transistor, current flows from the emitter to the collector. How they turn on and off is also different. An NPN transistor is powered on when a sufficient current is supplied to the base of the transistor. Therefore, the base of an NPN transistor must be connected to positive voltage for current to flow in.