SCR Question

[sundin13]

Hey I'm a  ;Dtech student in need of some help.

A 34V dc supply is applied to an SCR in series with a resistor, R.  When the SCR is turned on, its Ih= 6mA, and V a-k= 0.7 V.  What is the minimum value of R before the SCR can turn off?

Rmin=_______ohms  rounded to the nearest hole number.

Do I just divided 34V by 0.006 Amps  or would that be the Max value...

Confused???  Any help would be great...

 

[audioguru2]

Hi Sundin,
Think about how much voltage will be across the resistor. It is less than 34V. That voltage divided by the spec'd holding current determines the minimum value of the resistor. What about the tolerance of the resistor?

 

[sundin13]

Oh yeah series circuit basics.  Ooops...So the other voltage drop would be 33.3 Vdc.  Now the smallest the Resistor value before turn off would be 33.3 divided by .006

5550 Ohms......Am I right?

Resistor tolerences are not factored in.  Thanks Audioguru

 

[audioguru2]

Hi Sundin,
You are correct! ;D