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.
The price we pay for this is gain, which is slightly less than unity. Because the AC cathode follower is normally used only as a transparent buffer for driving difficult loads, it makes sense to use a medium- to high -current valve that can provide plenty of drive. The ECC83 / 12AX7 is a weakling in this regard, although for guitar applications it is often 'good enough'.