1. Rad Tech 110
Circuits

2. Conditions Necessary X-ray Production
High voltage
In the kilovoltage range
Electrons
A supply of electrons
A need to stop the electrons suddenly

3. Types of Transformers
Shell type
Core type

4. How do transformers work?
They can only work using AC current
On the principle of induction
Mutual
Self
The basic premise is that AC current ‘induces’ alternating magnetic fields.

5. Transformers work?
These alternating magnetic fields are distributed throughout the core of the transformer.
The alternating magnetic fields ‘induce’ an electrical current in loops (coils) of wire.

7. What gets transformed? Both voltage and current
In a step-up transformer the voltage is increased
The primary side (incoming) has less coils than the secondary (outgoing) side.
Because there are more coils on the secondary side a higher voltage is produced
Increases voltage is reflected as a higher amplitude of the waveform.

8. This occurs due to the conservation of energy.
At the same time as voltage increases the current correspondingly decreases.
This occurs due to the conservation of energy.
If you increase one aspect, voltage, you have to decrease the other, current.
(Voltagep)(currentp)=(voltages)(currents)

9. Step down transformer
Here the primary side has more coils than the secondary side.
The result is a decrease in voltage through the transformer.

10. The X-ray Circuit

11. Three sections of the x-ray circuit
Operating (control) console
High voltage generator
X-ray tube

12. Operating (control) console
Line voltage compensator
Autotransformer
kVp selector
mA selector
Timer
Pre-reading kVp meter

13. Line voltage compensator
The purpose of the line voltage compensator is to maintain a constant voltage to the system.
In the modern system this is done automatically.

14. Autotransformer
The autotransformer works on the principle of self-induction. It has a single core and is responsible for varying the voltage.
Because of its ability to adjust voltage, the autotransformer can be either a step-up or step-down transformer.

15. kVp selector kVp is adjusted at the autotransformer
Taps are available so that different voltages can be achieved.

16. Pre-reading kVp meter
The kVp meter is considered pre-reading because it is not actually measuring kVp but measuring voltage off the autotransformer.
Remember, the autotransformer is used to adjust voltage.

17. Timer Historically, there have been many types of timers.
Today, all timers are electronic timers of various types.
mAs
Phototiming (AEC)
Regular electronic

18. mA selector Allows for adjust of the filament voltage
Precision resistors
Choke coil

19. High Voltage Generator
Step-up transformer
High voltage transformer
High tension transformer
Step-down transformer
Filament transformer
Rectifiers

20. Step-up Transformer
This transformer is responsible for producing the high voltages necessary for x-ray production.
Turns ratio of 500:1 or 1000:1

21. Filament Transformer Intended to lower voltage and increase current
Allows for thermionic emission to occur at the filament
Ultimately, provides the electrons necessary for x-ray production.
Tube current measured in mA.

22. Rectifiers Current traffic cops
Intended to allow electrons to flow in only one direction
Provide the mechanism that converts AC to DC current.
4 rectifiers are required to fully convert AC to DC.

23. Types of Circuits Single phase Three phase Medium and High Frequency
Full wave
Half wave
Three phase
6 pulse
12 pulse
Medium and High Frequency
Capacitor discharge
Found predominantly in portables.

24. Single Phase
Full
Half

25. Three phase
6 pulse
12 pulse

26. Three phase transformers
Three phase units use delta and ‘wye’ transformers
6 pulse
2 ‘wye’ and 1 delta
12 pulse
2 delta and 1 ‘wye’
They also require 12 rectifiers

27. Advantages of 3 phase Higher beam quantity and quality
Higher mA stations are also possible

28. Why higher quantity and quality for three phase?
Because the voltage ripple is less
Basically when the tube is energized it stays energized.
full
3 phase 12 pulse

29. Medium/High Frequency Generator