The circuit posted here is of preamplifier for ceramic pick-up having moderately high input impedance about 470Ω and voltage gain more then 12.
Circuit Description of Preamplifier for ceramic-pickup
The circuit of preamplifier for ceramic-pickup is build around FETs because it have outstanding low-level characteristic including a high input impedance and low noise. These characteristic make the FET a natural choice at the input stage of a preamplifier for accepting signals from high-impedance transducers such as ceramic-pickup.
Inputs from ceramic microphone are given to base of FET through coupling capacitors C1. Vcc of 24V is given to collector which senses the additional function of providing the base current. In this circuit bypass capacitors C2 offers an almost short circuit and prevent loss of amplification. Output is taken from collector through capacitor C3 which is also coupling capacitors.
PARTS LIST OF PREAMPLIFIER FOR CERAMIC-PICKUP
Resistor (all ¼-watt, ± 5% Carbon)
R1 = 470 KΩ
R2 = 10 KΩ
R3 = 3.9 KΩ
C1 = 0.1 µF
C2 = 22 µF/12V
C3 = 10 µF/16V
T1 = BFW11