Equations and Variables

What does r’d mean

dynamic resistance

What is the equation linking capacitance, charge stored and voltage across

c = q/v

What is the equation for energy stored in a capacitor

1/2CV

What is the equation for capacitance

plate area x dielectric constant / plate separation

What is the equation for dialectic constant

Material permittivity/permittivity of free space

What is the equation linking voltage and turns in transformers

Vs/Vp = Ns/Np

What is the equation linking current and turns for transformers

Is/Ip =Np/Ns

What does V_p(out) mean

Peak voltage output

What is the equation for time constant

T = RC

What is the equation for time period

1/f

What is the equation for ripple factor

Vr(p-p)/Vdc

What is V_r(p-p)

Ripple voltage

What is V_DC

The DC magnitude carried by the wave form

What is V_z (diodes)

Zener voltage

What is Z_z

Zener impedance

What is the equation for Zener impedance

Change in Zener voltage/change in current

What is I_zk

The minimum amount of current needed to keep the diode in the Zener region

What is I_zm

The maximum about of Zener current that can be sustained before the diode damages

What is the equation for I_zm

Pd/Vz

What is P_D (diodes)

The max power the diode can take

What is Beta (BJTs) and where is it found

The DC gain and found in the data sheet

What is H_fe another name for

Beta

Why are BJTs better at amplification than FETs

As they have a higher value of gain, meaning they have a higher amplification factor

What is alpha (BJT’s)

The ratio of Ic to Ie

What does V_CEsat stand for (BJTs)

The collector - emitter saturation voltage

How do you calculate R_th

add r1 and r2 in parallel

How do you work out E_th

Voltage divider to work out r2

What condition must be met to use approximate analysis on this configuration

Beta times Re must be greater than or equal to 10R2

What approximation is made when using the approximate analysis

Ib = 0

How is V_B calculated for the approximate analysis

Voltage divider for r2

What is the current flowing through the N region for a JFET know as

Id

What is the controlling element for FETs

Vgs

What is the pinch point (JFETs)

Where the depletion region has expanded and joined at the top

What is V_P (JFETs)

Pinch off voltage

What is I_DSS

The current at the saturation point, where the current will not increase anymore

What is V_O (OP-AMP)

Voltage output

What is the equation for the output of an OP-AMP

V0*A

What is A (OP-AMP)

Gain

How is the differential voltage calculated (OP-AMP)

Vd = V1 - V2

What is V_D (OP-AMP)

Differential voltage

What is V_D equal to when the input is different (OP-AMP)

V1-v2

In common mode how do you work out V_d (OP-AMP)

V1 - V2

What is the input for common mode treated as (OP-AMP)

Average of the 2 inputs

What is the final output for common mode

AcVc + AdVd

How is common mode rejection ratio calculated (OP-AMP)

Ad/Ac

If common mode rejection ratio is calculated with logs, what would it be multiplied with (OP-AMP)

20log10

What is the equation for gain (OP-AMP)

V1/V0

How is the gain for each input calculated for this circuit

Rf/Rx

What is the resistance given by a capacitor (unrationalised)

1/jwc

What is the resistance given by a capacitor (rationalised)

-j/wc

What does wc equal (capacitor)

s

What is capacitor resistance in laplace

1/sC

What is x_c (OM-AMP)

Capacitor resistance

What does 1/s mean

Integrate

What does S mean

Differentiate

What is the closed loop gain for a oscillator circuit

A times beta

What is beta in an oscillator circuit

The gain form the feedback circuit

What is V_BR (thyristor Shockley diode)

Breakover voltage

What is breakover voltage (thyristor Shockley diode)

The minimum voltage to turn the device on

What is I_A (thyristor Shockley diode)

The current passing though the device

What is V_AK (thyristor Shockley diode)

The voltage applied over the anode and cathode

What is I_s (thyristor Shockley diode)

Switchover current

What is switchover current (thyristor Shockley diode)

The current at the point where the device starts conducting

What is I_H (thyristor Shockley diode)

Holding current

What is holding current (thyristor Shockley diode)

The minimum current required to keep the device is on state