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I've the following analog amplifier:

schematic

simulate this circuit – Schematic created using CircuitLab

The Vin is the input voltage of the amplifier and the V- system and the V+ system are the two points where I can controll the motor with the amplifier.

The questions I've are:

  1. Has this amplifier a specific name?;
  2. I think that the resistor R1 is a resistor to limit the current, but how does it do that?;
  3. I think that R2 is a resistor to controll the voltage at the input of the voltage follower, but I can I caluclate that volateg?
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  • \$\begingroup\$ seems to be a homework question. You should at least try to come to a solution yourself and tell us where you are stuck/ what you do not understand. \$\endgroup\$ – Sir Sy May 31 '18 at 7:16
  • \$\begingroup\$ @SirSy It isn't a homework question. And I set my thoughts in the question (like that I think that R1 is a resistor to limit the current). \$\endgroup\$ – asd May 31 '18 at 7:17
  • \$\begingroup\$ It is a Darlington transistor. \$\endgroup\$ – Sir Sy May 31 '18 at 7:35
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Has this amplifier a specific name?

It's a voltage controlled current sink. Vin is a demand voltage and the transistors turn on sufficiently to take a current through the load that equals \$I_{LOAD}\times R_2\$.

I think that the resistor R1 is a resistor to limit the current, but how does it do that?

That is what resistors do - if you apply a voltage across tthem they restrict the current as per ohms law. R1 is probably needed to restrict the base current into T2 should the motor (say) become stalled.

I think that R2 is a resistor to controll the voltage at the input of the voltage follower

Answered above.

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