difference between the two circuits

[vicky29]

hi friends,
can someone please explain the difference between the two circuits shown in the picture?

thanks a lot in advance,

 

[armsgroup]

if you just make the led on with power of course no difference but if you measure the voltage in mid point the voltage will differs

 

[echo47]

Both circuit work the same, but I always use the second one because it survives when I slip and touch it with my oscilloscope ground clip.

 

[MRFGUY]

It is the same circuit (same current, and same voltage across LED).

 

[Btrend]

if ESD protection is considered, the second one is more better.

 

[csr1981]

functionally both the circuits are same but the second circuit is more better because when supply is switched on,the surge current is not directly applied to the LED it goes through the resistor.

 

[fantaci]

if ESD protection is considered, the second one is more better.

Could you explain it in detail?

 

[Btrend]

in my opinion.
1. PN junction (in diode) has breakdown voltage
2. if ESD test is doing in both cases, the first one PN junction will see high ESD pulse, however the seconde one will not see the full ESD pulse, cause there is I*R drop before the PN junction breakdown.

 

[xiongshoufen]

if ESD protection is considered, the second one is more better.

i also think so

 

[echo47]

Please explain your ESD reasoning more clearly. Where is the ESD pulse being applied? The parts are in series, so the same current flows through both of them.

 

[Jawn]

I don't understand how the second one can be better. The actual current of electrons will flow through the diode first in the second diagram.

 

[klj55888]

it's the same ,but the sevond one be applyed most