# whats this circuit?

Discussion in 'Homework Help' started by ztigmax, Sep 12, 2015.

1. ### ztigmax Thread Starter New Member

Sep 12, 2015
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what is this circuit?what does it do?

2. ### cornishlad Member

Jul 31, 2013
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It looks like a direct coupled amplifier - or it could be if there was an input connection.

Last edited: Sep 12, 2015
3. ### blocco a spirale AAC Fanatic!

Jun 18, 2008
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It looks like something from a test paper rather than a functioning circuit.

4. ### tom_s Member

Jun 27, 2014
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transistors and resistors

absf likes this.
5. ### cornishlad Member

Jul 31, 2013
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I was tempted to add "is this for real ?"

6. ### atferrari AAC Fanatic!

Jan 6, 2004
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Inputless multistage amplifier used in a time-wasting machine. Probably prone to oscillate madly.

7. ### absf Senior Member

Dec 29, 2010
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If this is homework then the question should be :

"Find the value of V1 if VCC is 10V and get datasheets of the 2 transistors using Google."

Allen

Sinus23 likes this.
8. ### GopherT AAC Fanatic!

Nov 23, 2012
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Assuming the input is on the left, between the two 10k resistors, I would say this circuit is more of a power attenuator while at the same time, a voltage amplifier. Overall, i would say it is a mess.

9. ### OBW0549 Well-Known Member

Mar 2, 2015
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It's called a "student confuser."

It provides an output voltage, V1, whose value you're supposed to calculate.

Other than that, it has no discernible function.

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10. ### dl324 Distinguished Member

Mar 30, 2015
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An example of how to not draw a schematic??

It makes me cringe and wonder why the author didn't make any attempt to line up the resistors, use uniform spacing between transistors, and remove those unnecessary bends.

Aside from being useless...

11. ### DickCappels Moderator

Aug 21, 2008
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Or it can be a bandgap voltage reference or a temperature measurement circit.

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12. ### Lestraveled Well-Known Member

May 19, 2014
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I think absf got it right. It is an exercise in calculating bias points.

absf likes this.
13. ### ian field AAC Fanatic!

Oct 27, 2012
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I'm surprised no one entered it into a Spice simulation yet!

14. ### OBW0549 Well-Known Member

Mar 2, 2015
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I would, but I'm too lazy. Just eyeballing the circuit, and assuming Vcc is around 10 volts, I'm thinking Q5 and Q6 are both saturated and the output at V1 is therefore something in the vicinity of 0.10 X Vcc.

15. ### JoeJester AAC Fanatic!

Apr 26, 2005
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Maybe it's one of the circuits listed on the patent in one of the many over-unity devices ... or an "instructable".

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16. ### ScottWang Moderator

Aug 23, 2012
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I'm curious does Mike going to somewhere on vacation, otherwise he might do that?

17. ### #12 Expert

Nov 30, 2010
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Dick Cappels posted my first thought (post#11). Then I ran the circuit (simulated) in my head and found it's a saturated output transistor. Now I agree with OBWO (post#9).