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54 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Pulsating DC |
Current that varies in amplitude but does not reverse polarity |
Not alt. Current because polarity remains the same |
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Protection. In SCR |
Optional section in an scr power supply. Prevents damage to power supply from excess current flow |
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Diode reflecters |
AC to DC |
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Power Supply |
AC to DC |
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Half Wave Diode Reflector |
AC to DC VDC=VPeak of secondary x .318 |
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Full Wave Diode Rectifier |
AC to DC VAVG= [VPP/2] x .636 If center tapped: VAVG= [VPP/4] x .636 Diodes preform reflection 180° out of phase |
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Bridge Diode Rectifier |
Only conducts if forward biased VAVG= VPEAK x .636 Output: pulsating DC |
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Half Wave rectifier freq |
Ripple req: same as input freq |
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Full wave rectifier freq |
Ripple freq: twice input freq With half VPEAK output |
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Bridge rectifier freq |
Ripple freq: twice input freq Output: twice the voltage of a fullwave |
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Advantage of a Bridge vs Fullwave |
Applied voltage is taken across the full potential of the transformer |
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Voltage regulators -purpose |
Adjust voltage to maintain Eout at a constant level |
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Zener diode normal operation |
Fwd biased: low ohms Rev biased: high ohms |
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Zener diode |
Series voltage regulator |
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Efficiency of a full wave vs half wave |
Full wave is more efficient because an output is developed for entire wave form |
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Purpose of a series volt regulator |
Maintain constant output voltages to a load |
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In a series volt regulator... |
Load current ^, r1 √ = er √ |
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In a Parallel volt regulator... |
Eout ^ if DC in ^ OR current of load √ |
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Zener Diode is rev bias when |
Rev bias when anode (+) is more - than cathode (-) |
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In a zener reg.. Q1 Fwd bias increases when... |
Q1 is fwd bias ^ when load current ^ |
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In a variable volt regulator... |
Q1 maintains output voltage level |
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In a variable volt regulator... |
If input V ^, Q1s voltage also ^ |
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How to reverse bias an SCR with a multimeter |
Put meters negative port on anode |
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How to check an SCR gate |
Current is applied by jumper cables from anode to gate |
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Polarized Outlet |
Ensures hot wire is not common to chassis and isolates the circuit from AC line |
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Voltage doubler is used when... |
When in need of high volt and low current |
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Voltage doubler purpose |
Change AC voltage into DC with a substantial ^ on magnitude |
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Half wave voltage doubler |
RMS x 1.414 =PEAK C2 >/ peak in x2 |
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If load is added to a voltage doubler |
Ripple ^ and output √ |
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Voltage multiplier vs current vs output |
The higher the multiplication factor, the worse the ripple , the lower the output, higher the component rating must be. Lower the multiplier the higher the current |
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IC Regulator 7812 |
Max current: 1.5 A Regulates to 12 volts RL sould never drop below 8 ohms |
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Trigger devices |
Solid state decides that turn on (trigger) when input exceeds a specified value. |
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Unijunction UJT |
Switch voltage 'On' when input voltage exceeds a specified value OR Base 1 to emitter current flows |
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Silicon Control |
Switches current 'On' when input current is applied to an element OR when current flows from cathode to anode |
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SCR turns off when... |
When current is interrupted. I.E. by shorting to ground via a switch. Otherwise remains latched' |
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Unijunction has how many PN junctions |
One PN junction |
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Silicon Control has how many PN junctions |
3pn junctions (P material for gate aswell) |
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Interbase resistance |
High resistance between two bases (RBB) ETA= Rbb1/(Rbb1 + Rbb2) Turn on voltage = ETA x VCC |
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Holding current (SCR) |
Minimum current required to sustain current flow keeping on =Ih |
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In an UJT Q1 turns on when... |
Q1 turns on when charge on C1 reaches Q1s TURN ON VOLTAGE |
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Normal component faulting in VOLTAGE REGULATOR |
Zeiner Diodes |
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IC Regulator vs Multicomponent regulator |
IC advantage over Multi: interthermal protection |
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SCR + Gate |
Gate of SCR is connected to Cathode |
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UJT operation is based on... |
Based on RC TIME CONSTANT |
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What is the effect on Rbb when emmiter is collected between two bases.. |
Rbb is divided in two, forming a volt divider |
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SCR power control purpose |
To rectify and control amount of power applied to load |
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SCR power control equations |
Erms= .707 x E Peak Eave = Erms x (C/ 360) C as in fireing angle P= E^2 /R OR P= Eave^2 / R |
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Most common fault in an SCR Power Control |
Failed semiconductor component (entire SCR) |
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SCR power control: Open vs Short |
Short: On all the time Open: stops current flow - no voltage is developed across load in either circuit |
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SCR power control trouble shooting steps |
1. Determine type ( trigger or power control) 2. Check applied voltage and gate signal 3. Check external signal path 4. SCR 5. Isolate fault |
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Relay definition |
An electro-magneticly operated switch |
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How many poles can a relay have? |
One or more |
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Thermal Time Delay |
Thermal big matalic strip as common terminal |
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Twerk |
Twork |
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