Rectification and Diodes

Frequency of AC current

60 cycles/sec (1/60th)

What symbol demonstrates one complete AC cycle

Full sine wave

How many times does AC change directions

120 times

What do diodes do

they allow electricity to flow in only one direction and blocks the other

What is the name of the process of changing AC to DC

Rectification, diodes work in pairs

After converting AC to DC, the waveform is now called

Full wave DC rectification

What type of current goes into and out of circuit without diodes

AC

What type of current goes out of a circuit with diodes

DC

What are unwanted pulses in XR deviation

Ripples

What are ripples

deviation of the voltage waveform across XR tube from constant voltage

What do ripples cause in terms of XR production

causes lengthening of exposure time and higher variations

How can you reduce ripples in the waveforms

Change the incoming line voltage or wiring

On a waveform, with diodes what happens

power will never dip to 0 and ripples are smaller

Three Phase Power generators

produce almost constant potential diff across XR tube

Three phase 6 pulse

6 pulses per HZ or 360 pulses per second

Three phase 6 pulse ripple factor

13-25%

Three phase 12 pulse

12 pulses per 1/60th second or 720 pulses per second

Medium/High frequency generator

produces nearly constant potential voltage waveform

Medium/High frequency generator ripple factor

<1%

Why is the medium/high frequency generator most efficient

• costs less to operate

• better image quality

• lower patient dose

Ammeter

measures electric current

Voltmeter

measure electric potential

Battery

Source of emf, provides electrical potential

When batteries cannot supply current as fast as your circuit drains them, you would use

capacitors

Capacitor

momentarily stores electric charge

Standard unit of capacitance

FARAD

Diodes/Rectifiers

allows electrons to flow in only one direction

Why is it best for current to flow in a single direction

to protect your xray circuitry

Ohmmeter

measures electrical resistance

Ground

safety device to reduce risk of electric shock

How does the ground reduce risk of electric shock

makes low resistance path for current to flow to earth instead of body

Resistor

inhibits flow of electrons

Rheostat

adjustable, variable resistor

Transformer

increases/ decreases voltage by fixed amount

Step Up transformer

less windings on primary than secondary

What happens to the voltage and current in a step up transformer

increases voltage on primary and secondary side while decreasing current

STep down transformer

more windings on primary side than second

What happens to the voltage and current in a step down transformer

decreases voltage from primary and secondary while increasing current

Wye (star) transformer

• named after the way the windings are connected inside transformer

• 3 phase equipment

Delta transformer

windings of three single-phase transformers
connected in series with each other

Fuse

safety device will blow if current flowing exceeds specific value