Input voltage:

Top resistor:

Bottom resistor:

20

Oct

2019

Input voltage:

V
⚠

Top resistor:

Ω
⚠

Bottom resistor:

Ω
⚠

19

Aug

2019

lm
⚠

°
⚠

\Omega_{sr} = 2\cdot\pi\cdot(1-\cos(\frac{\theta}{2}))

I_{v} = \frac{\Phi_v}{\Omega_{sr}}

where:

- \theta is the
*apex angle*in radians - \Omega_{sr} is the
*solid angle*in Steradians - \Phi_v is the
*luminous flux*in lux (*lx*). - I_{v} is the
*luminous intensity*in candela (*cd*).

You can use the UliEngineering library like this:

from UliEngineering.Physics.Light import lumen_to_candela_by_apex_angle from UliEngineering.EngineerIO import auto_format, auto_print # These are equivalent: intensity = lumen_to_candela_by_apex_angle("25 lm", "120°") # intensity = 7.9577 (cd) intensity = lumen_to_candela_by_apex_angle(25.0, 120.0) # intensity = 7.9577 (cd) # ... or get out a human-readable value: intensity_str = auto_format(lumen_to_candela_by_apex_angle, "25 lm", "120°") # "7.96 cd" # ... or print directly auto_print(lumen_to_candela_by_apex_angle, "25 lm", "120°") # prints "7.96 cd"

In case you can’t use *UliEngineering*, use this Python function:

import math def lumen_to_candela_by_apex_angle(flux, angle): """ Compute the luminous intensity from the luminous flux, assuming that the flux of <flux> is distributed equally around a cone with apex angle <angle>. Keyword parameters ------------------ flux : value, engineer string or NumPy array The luminous flux in Lux. angle : value, engineer string or NumPy array The apex angle of the emission cone, in degrees For many LEDs, this is >>> lumen_to_candela_by_apex_angle(25., 120.) 7.957747154594769 """ solid_angle = 2*math.pi*(1.-math.cos((angle*math.pi/180.)/2.0)) return flux / solid_angle # Usage example print(lumen_to_candela_by_apex_angle(25., 120.)) # Prints 7.957747154594769 (cd)

07

Aug

2019

C
⚠

V
⚠

You can use the UliEngineering library like this:

from UliEngineering.Electronics.Capacitors import capacitor_energy from UliEngineering.EngineerIO import auto_format, auto_print # These are equivalent: energy = capacitor_energy("100 uF", "24 V") # energy = 0.0288 (J) energy = capacitor_energy(100e-6, 24.0) # energy = 0.0288 (J) # ... or get out a human-readable value: energy_str = auto_format(capacitor_energy, "100 uF", "24 V") # "28.8 mJ" # ... or print directly auto_print(capacitor_energy, "100 uF", "24 V") # prints "28.8 mJ"

In case you can’t use *UliEngineering*, use this Python function:

def capacitor_energy(capacitance, voltage): return 0.5*capacitance*voltage*voltage # Usage example: print(capacitor_energy(100e-6, 24.0)) # prints 0.0288 (J)

07

Aug

2019

*IEC 60384-14* specifies that X1/X2-rated capacitors shall be tested to withstand an * impulse voltage *of

However these values * only apply for a capacitance \leq 1 μF* (except for Y1/Y4 capacitors)

F
⚠

where:

- Up is the impulse withstand voltage rating
- C is the capacitance in Farads
- Up_{\leq 1 μF} is the voltage rating for that capacitor class with a capacitance of \leq 1 μF:
- For X1-class:
*4 kV* - For X2-class:
*2.5 kV* - Y1-class impulse withstand voltage is
*always*8 kV no matter what capacitance - For Y2-class:
*5 kV* - Y4-class impulse withstand voltage is
*always**2.5 kV*no matter what capacitance

- For X1-class:

The rationale behind the *derating *of the impulse withstand voltage is that larger capacitances will have sufficient capacitance so that a given overvoltage doesn’t cause a large voltage spike in the capacitor.

The formula (see above) is chosen so that the energy in the capacitor:

E = \frac{1}{2}\cdot{}C\cdot{}U_p^2is kept constant (i.e. at the same value as for a equivalent capacitor of *1 μF*).

30

Jul

2019

Use this online calculator to compute the reactance of an inductor in Ω at a specific frequency given its inductance.

Also see Capacitive reactance online calculator & Python code

H
⚠

Hz
⚠

The preferred way is to use UliEngineering’s `UliEngineering.Electronics.Reactance.inductive_reactance`

:

from UliEngineering.Electronics.Reactance import * # You can either pass strings like "150 uH" or values like 150e-6 inductive_reactance("150 uH", "10 MHz") # returns 9424.77796076938

Or get a human-readable value:

from UliEngineering.Electronics.Reactance import * from UliEngineering.EngineerIO import * # Compute value as a string xc = auto_format(inductive_reactance, "150 uH", "10 MHz") # "9.42 kΩ" # ... or print directly auto_print(inductive_reactance, "150 uH", "10 MHz") # prints "9.42 kΩ"

In case you can’t use *UliEngineering* and you want to do it manually, here’s a minimal example:

import math def inductive_reactance(f, l): """Compute the inductive reactance""" return 2*math.pi*f*l

30

Jul

2019

Use this online calculator to compute the reactance of a capacitor in Ω at a specific frequency given its capacitance.

Also see Inductive reactance online calculator & Python code

F
⚠

Hz
⚠

The preferred way is to use UliEngineering’s `UliEngineering.Electronics.Reactance.capacitive_reactance`

:

from UliEngineering.Electronics.Reactance import * # You can either pass strings like "150 pF" or values like 150e-12 capacitive_reactance("150 pF", "10 MHz") # returns 106.1032953945969

Or get a human-readable value:

from UliEngineering.Electronics.Reactance import * from UliEngineering.EngineerIO import * # Compute value as a string xc = auto_format(capacitive_reactance, "150 pF", "10 MHz") # "106 Ω" # ... or print directly auto_print(capacitive_reactance, "150 pF", "10 MHz") # prints "106 Ω"

In case you can’t use *UliEngineering* and you want to do it manually, here’s a minimal example:

import math def capacitive_reactance(f, c): """Compute the capacitive reactance""" return 1./(2*math.pi*f*c)

29

Jul

2019

Use this online calculator to convert a voltage in Volts to a voltage in dBµV.

Also see dBµV to Volts online calculator & Python code

V
⚠

import math def volts_to_dbuv(v): """Convert a voltage in volts to a voltage in dBµV""" return (20*math.log(1e6 * v))/(math.log(2) + math.log(5))

29

Jul

2019

X
⚠

Y
⚠

X
⚠

Y
⚠

28

Jul

2019

Use this online calculator to convert a voltage in dBµV to a voltage in Volts.

Also see Volts to dBµV online calculator & Python code

dBµV
⚠

def dbuv_to_volts(dbuv): """Convert a voltage in dBµV to a voltage in volts""" return (10**(dbuv/20.))/1e6

15

Mar

2019

Use this online calculator to calculate the power dissipation in a purely resistive load. Continue reading →