Rectification Flashcards
What is rectification in the context of electrical circuits?
Rectification is the conversion of an alternating current (AC) to direct current (DC). The electronic circuit that performs this conversion is known as the rectifier circuit.
Why is a high value of steady DC voltage ideal for x-ray tubes?
A high value of steady DC voltage is ideal because it ensures a consistent x-ray emission for the duration of the exposure.
Name some applications of rectifiers.
- Rectifiers are used in demodulators,
- AM radio circuits,
- Uninterruptible Power Supply (UPS) circuits,
- home inverters
- battery chargers for mobile phones and laptops.
Why is an alternating potential difference (PD) across the x-ray tube undesirable?
- inverse PD produces no x-ray emission,
- the sinusoidal changing PD results in a continually changing x-ray beam intensity, which can damage the x-ray tube.
What is half-wave rectification?
Half-wave rectification utilizes only alternative half-cycles of the AC signal, meaning only one-half of the total number of half cycles is used, and the x-ray beam is alternately switched on and off.
What are the two circuits used in half-wave rectification?
- self-rectified
- 2-diode half-wave rectified circuits.
How does the 2-diode half-wave rectification circuit improve upon the self-rectified circuit?
- use of two diodes to prevent inverse voltage across the x-ray tube
- separating the functions of rectification and x-ray production.
What is full-wave rectification and how is it achieved?
Full-wave rectification uses all half-cycles of the AC signal to produce x-rays, achieved by using four diodes in the secondary circuit of the high tension transformer (HTT).
What are the benefits of using two diodes in half-wave rectification?
The circuit is symmetrical, giving equal values of kV to the ends of the X-ray tube.
Failure of one diode does not damage the X-ray tube as the other diode will prevent reverse current flow.
What is the purpose of four-diode full-wave rectification?
To utilize all half-cycles of the AC signal, allowing a greater range of exposure settings and continuous X-ray production.
How does a four-diode full-wave rectification circuit work?
Four diodes are used in the secondary circuit of the high tension transformer, ensuring that the voltage across the X-ray tube is fully rectified and the anode is always positive with respect to the cathode.
