Diode circuit calculation

[nicksydney]

Hi,

I'm learning about Diode and I've done some calculation that I want to check with the folks in the forum to confirm whether I'm doing it the right or wrong way.

Below is the formula I'm using (the 0.7v that you see in the formula is the voltage drop for silicon diode)

View attachment 63167

Below is the circuit that I've drawn up in LTSpice

View attachment 63171

and below is the waveform that I got from LTSpice for the circuit

View attachment 63169

The below screenshot shows the waveform when I place the probe between the diode and R2.

View attachment 63170

When I calculate using the formula I can get the same voltage as the voltage between the Diode and R2 - for example if I use R1 = 3550, R2=1500 and V1=10v , using the formula I'm getting -2.76v same as voltage recorded in LTSpice.

Just want to confirm whether I'm on the right track to calculate the voltage between the diode and R2 using the formula ?

Thanks

 

[ericgibbs]

hi,

If you assume a forward voltage drop of 0.7V across the diode, you subtract this from the 10V supply.

So thats 10-0.7=9.3V the total resistance of the two resistors is 2K.

So the current on the Negative half cycle will be 9.3/2k = 4.65mA

Then the Vdrop across the 750R is 750*.00465 = 3.48V

 

[nicksydney]

Hi ericgibbs,

Thanks for the reply.

Cheers

 

[crutschow]

Just remember that the actual voltage drop across a diode depends upon the diode type and current rating, and the current through it.