2N2222 datasheet – 2N2222 is a NPN switching transistor in a TO-18 metal package and his PNP complement is 2N2907A.

BD139, BD140 are epitaxial planar transistors which are mounted in the SOT-32 plastic package. They are designed for audio amplifiers and drivers utilizing complementary or quasi-complementary circuits. The NPN types are the BD135 and BD139, and the complementary PNP types are the BD136 and BD140.

The TBA120 Series ICs provide a high-gain limiting IF amplifier and a quadrature coincidence detector in one package. These ICs are primarily intended for extraction of TV intercarrier sound, which (in Europe) is frequency modulated onto a 5.5MHz or 6MHz subcarrier. The TV waveform constitutes an extreme interfering signal, and the TBA120 provides superior performance in comparison to early Foster-Seeley and Ratio Detector systems, with a considerable reduction in component count.

The ISD2500 ChipCorder family of ICs from Winbond contains almost all the necessary hardware in a single IC to record and playback audio messages. Included on the IC is a microphone preamp and AGC suitable for a low-cost electret type microphone, an output amplifier to drive a loudspeaker, memory, an oscillator, an A/D and a D/A converter. There are four basic models; 2560, 2575, 2590 and 25120, the numbers following 25 indicate the available recording time in seconds. The memory capacity of each version is actually the same but longer recording times are achieved by using a lower sampling rate. The chip with the shortest recording time therefore offers the best audio quality.