| 摘要 |
PURPOSE:To set optionally a level of an output signal by using a current changeover circuit and a constant voltage source applying a prescribed voltage thereto. CONSTITUTION:To collector of a transistor (TR)1 receiving an input signal is grounded and the emitter is connected to a power supply VEE through resistors 11 and 2. Further, a connecting point between the resistors 11 and 2 is connected to the current changeover circuit comprising TRs Q1, Q2 and a constant current source. Further, a collector of the TRs Q1, Q2 is connected respectively to the emitter of a TRQ3 via resistors R1, R2 and a constant voltage source V1 is connected to the base of the TRQ3. The level of the output signal is changed optionally by setting the constant voltage source V1 and the constant current source in extracting the output signal from the collector of the TRQ1 or Q2. |
