# Voltage Controlled Current Source (VCCS)

Here is a circuit that contains a Voltage Controlled Current Source (VCCS). The gain of the VCCS can be changed using the scrollbar.

When the gain of the VCCS is equal to 0.25 A/V this is the circuit considered in problem P2.7-2 of
**Introduction to Electric Circuits, 7e** by R.C. Dorf and J.A. Svoboda. In problem P2.7-2 the gain of the VCCS is denoted by the symbol g. Then

I_{a} = g * V_{b}
where g is the gain of the dependent source. Notice that the units of g are A/V. The current I_{a}, in Amps, and voltage V_{b}, in Volts, are measured using the voltmeter and ammeter. Thus the gain of the dependent source can be determined from the meter readings.

In this circuit

V_{b} = V_{s}* R_{2} / ( R_{1} + R_{2} )
where R_{1} = 50 Ohms, R_{2} = 25 Ohms and V_{s} = 24 V. (See, for example, Section 3.3 of **Introduction to Electric Circuits, 7e**.) Thus

V_{b} = 8 V
regardless of the value of the gain of the VCCS.

### Challenges:

- Set the gain of the VCCS equal to 0.25 A/V to check the answer to problem P2.7-2.
- Determine the gain of the VCCS required to cause I
_{a} = 6 A. Verify that the meter readings are consistent with the gain of the dependent source.
- Predict the value of I
_{a} when the gain of the VCCS is 7.5 A/A. Check your prediction using the scrollbars.
- Predict the gain of the VCCS that will cause I
_{a} = 5 A. Check your prediction using the scrollbars.