Transistor Capacitance Multiplier Circuit The transistor capacitance multiplier can be used to give additional levels of smoothing in many areas of electronics. The basic capacitance multiplier circuit is essentially a simple emitter follower with a capacitor on the base and a feed resistor from the input to the base to turn the transistor on. A capacitor from the base to ground provides the smoothing. The capacitance multiplier circuit operation is quite straightforward. It acts as a simple emitter follower. The resistor R1 provides bias for the base emitter junction, and the capacitor provides smoothing. This considerably reduces the levels on noise on the output, i.e. Vout. The effect of placing the transistor in the circuit is that it effectively multiplies the capacitance on the base by the current gain of the transistor, i.e. by β The capacitance multiplier circuit is not a voltage regulator. The output voltage varies directly with the input Vin as there is no voltage reference. Generally the output voltage is about 0.65V less than the base voltage, and around 2 - 3 V less than Vin when a load is applied. Note there must be sufficient voltage drop across the transistor for its action to be made possible. The ripple and noise levels on the output can be reduced to very low levels> Increasing the values of R1 and C1 reduce the output ripple, and increasingly at low frequencies. On the downside large values of R1 and C1 cause the output to rise slowly towards the required value after turn on, because of the large time constant of R1 and C1.