Forgive me if I am wrong. But I doubt that the curve says the efficiency is around 20%
There are plenty of youtube videos that contradict this.Obviously efficiency cannot be greater than one
It comes from some logs. I mean logarithms. (it was introduced as a torture device for young students).
Forgive me if I am wrong. But I doubt that the curve says the efficiency is around 20%
Thanks for the clarifications.That is incorrect. No logs were used in the sim. It has to do with where I place
the current probe, entrance or exit of the device being probed.
Wrong....
Efficiency of a 3 terminal regulator -
View attachment 179056
Regards, Dana.
Hi,
The BD540 is a power transistor so we should expect it to have a low beta. In fact, its data sheet values confirms this. so, the base current should not be neglected.
I'd recommend you use the minimum value of beta as given in the datasheet.
Iout(worst case) = Ib*(beta + 1) + IR1
So if we let Ib to be one-tenth of IR1, we have: Iout(worst case) = 0.1*IR1*(beta + 1) + IR1
So that Iout(worst case) = IR1*(1.1 + 0.1*beta)
Therefore,
IR1 = Iout(worst case) / (1.1 + 0.1*beta)
R1 = Vbe/(IR1)
I have derived the equation as shown in the attachments below. In the equation for R1, everything after the division sign is the denominator. You can substitute ILOAD(max) and IREG(max) for ILOAD and IREG, respectively.For transistor Q2,
VBE(Q2) = 0.8 = ISC × RSC
From output side of the regulator we get,
ILOAD = IREG + IC1
From input side of the regulator we get,
IREG = IB1 +IC2 +IR1
IB2 =( β+1)× IE2
yesHi,
Do you see the Darlington between Input and Output?
I will look at what you have done in detail later on. However, I think I caught something. The expression you showed in a box on the last line of your first page is not what it should be. The relationship is IC3 = beta(Q3)*IB3. I'd encourage you start from there to review your work and then let us see what you have come up with. If there's another catch, we will let you know.Here is another example of an Outboard Current Boost Circuit. I am trying to find out the values of Rsc and R1 and R2.
But did not succeed. Can anybody remove the term IR1 in equation 5 so that only IREG, ILOAD, and IC2 remain in the equation??
In case if my solution is wrong then please solve this equation and find the values of Rsc, R1, R2, and R3 for me.
View attachment 179241
pleaseIf there's another catch, we will let you know.
Hello, Akanimo I cam not solve it. Can you solve it for me?I will look at what you have done in detail later on. However, I think I caught something. The expression you showed in a box on the last line of your first page is not what it should be. The relationship is IC3 = beta(Q3)*IB3. I'd encourage you start from there to review your work and then let us see what you have come up with. If there's another catch, we will let you know.
I believe it will be helpful to you if we take that path to get you to pick up the expressions you are missing in the derivation process.
Here is what I have done.Hello, Akanimo I cam not solve it. Can you solve it for me?
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