# PLC Relay Output Circuit

Can someone help with this question? I've answered it to the best of my knowledge based on the learning materials provided but the answers I've gotten are exactly the same as the example. Should 5v be 9v?

The assumptions are what I've been given from the learning material.

Basically just everything under 'Calculate' .

• Please edit your question to clarify which line you're having trouble with and why. – Transistor Dec 21 '18 at 20:04
• Unless the more transistor hFE data or a curve and Relay resistance are given, there is no guarantee the circuit is reliable as you need an hFE of 60 to generate 60mA from 1mA input and the result is is Vce will rise so hFE must also rise resulting is less voltage across the coil, with Icoil=V/R. So it is best to assume a lower hFE like 20 to achieve closer to Vce=Vce(sat) which by general rule uses Ic/Ib=10 – Sunnyskyguy EE75 Dec 21 '18 at 21:56
• @TheP: Your "Basically just everything under 'Calculate'" edit doesn't clarify anything. – Transistor Dec 23 '18 at 19:16