Miller-Transitron
The Miller-Transitron is a relaxation oscillator and is based on the Miller integrator . It was mainly used in tube-equipped television sets of the 1950s to generate the vertical deflection voltage, but could not prevail against the blocking oscillator also used at the time .
functionality
The anode voltage (approx. 200 V) is fed in at the upper terminal, while the sawtooth voltage can be taken from the terminal below. Synchronization pulses can be fed in at the node of the connection for the braking grid, which ensure the necessary synchronicity with the voltage curve on the transmitter side.
When the circuit is started up, the anode current flowing in R3 causes a growing voltage drop. This causes the anode voltage to drop below the screen grid voltage . The current flow now jumps away from the anode to the screen grid. This results in a sudden increase in the screen grid current, which in turn causes an increased voltage drop at R1: The screen grid voltage drops. This negative voltage jump is conducted via C1 to the braking grid, which further suppresses the anode current. C1 now discharges via R1 and thus allows an anode current again. These processes take place very quickly one after the other, so that in total only a positive jump in the anode voltage can be observed.
From this state on, the anode current increases again very slowly and linearly. The increase in the anode current (or decrease in the anode voltage) is transferred to the control grid via C2 . The increase in the anode current is inhibited by the negative polarity of the voltage curve on the control grid. R4, on the other hand, causes a counter voltage to this charging voltage resulting from the charging current. C2 and R4 form what is known as an integrator . The more C2 is charged to its final voltage, the lower the resulting negative voltage on the control grid: The capacitor is charged faster. Overall, this arrangement brings about a linearization of the charging voltage curve of C2, which in turn affects the anode current and via R3 also the anode voltage.
This process continues until the screen grid becomes more positive than the anode again, the emission current jumps back to the screen grid and the process starts all over again. A tilting oscillation can be measured at the anode .
References, literature
- Otto Limann: TV technology without ballast . 8th edition. Franzis Verlag, Munich 1969.
- Harley Carter: Little Oscillography . 3. Edition. Philips Technical Library, 1963.