optical switch circuit

For detail in this circuit ,i will be to present thus as below.
When the phototransistor (2N5777)is determined by the IR light, and leads to tension between the stroken 220k Ohm R resistance (any) for drive collector BC558 and the drop PHOTOTRANS from VCC to lower levels.
IC4027 TTL signal output will be drive to [...]

Simple Class A amplifier circuit

This circuit is that of a simple class A audio amplifier. But with zero distortion, Q1 is a switch in the on or off, so that no load current by the resistance R2. In the best case, the tension in Q1 and the load resistance must be equal to the class-A [...]

Here’s AC power supply circuit with low voltage output (step down transformer converter). Warning! This project involves the use of dangerous voltages. You must make sure all high-voltage (120 volt household power) conductors are safely insulated from accidental contact. No bare wires should be seen anywhere on the “primary” side of the transformer circuit. Be [...]