The BC547 is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin.
The 2N6027 Programmable Unijunction Transistor is designed to enable the engineer to “program’’ unijunction characteristics such as RBB, η, IV, and IP by merely selecting two resistor values.
The 2SC2371 is a Silicon NPN power transistors, TO-126 package, High voltage 300V 100mA high frequency. For TV chroma output and vertical output applications.
The DAC0808LCN is an 8-bit monolithic digital-to-analog converter (DAC), It will interface directly with popular TTL, DTL or CMOS logic levels, and is a direct replacement for the MC1508/MC1408. For higher speed applications.