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I'd like to ask how to set fixed bias for this transistor.. It doesn't seem to be working. If anyone know how to calculate it, please tell me.

I wanna adjust two resistor values so that Uce = 5,44V, Ube = 0,655V, Ucc = 12V and Ic (collector current) has to be 2,43 mA.

I tried R2 = (12 - 5,44) / 0,00243 = 2,7kOhm.

But in the second part where I wanna find R1, I don't know Ib (base current). Or can I find it out? I tried looking for BETA, but didn't find anything.

I tried editing Beta in Multisim but I couldn't click Edit Model because it was unclickable.

R1 = (12 - 0,655) / Ib

Any ideas? If yes, please add calculations if you did some and explanation. Thanks forwardly for every sensible comment!

enter image description here

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  • \$\begingroup\$ I wanna read actual English words. If you don't know beta then you must proceed with trial-and-error, and there is no guarantee that you will be able to get both the Vbe and the Ic that you desire. \$\endgroup\$ – Elliot Alderson Feb 18 at 21:02
  • \$\begingroup\$ I would like to know at least beta.. but i can't find out. I tried Edit Model inside Multisim to see what's inside. But it can't click it, it's not clickable. \$\endgroup\$ – MerryGR Feb 18 at 21:06
  • \$\begingroup\$ choose R1=2*hFE*Rc but if you want independent of hFE then you use H bias \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Feb 18 at 21:17
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    \$\begingroup\$ @StainlessSteelRat, on the other hand, if the transistor doesn't turn on, then voltmeter U2 should read 12 V. \$\endgroup\$ – The Photon Feb 18 at 21:29
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    \$\begingroup\$ @StainlessSteelRat I think the graphic is misleading. I think that U1 is a voltmeter but for some reason it is not displaying a voltage. \$\endgroup\$ – Elliot Alderson Feb 18 at 21:30
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Problem has been solved, I found Beta(min) and Beta(max) and somehow tried to find the Beta so the values could match with all the pre-defined values. I was experimenting a bit but it took a time.

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