A preamplifier operating on a single supply and suitable for use with high impedance type crystal pickups is shown here.The circuit is basically a non-inverting AC amplifier in which the gain is dependent on the feedback resistor R4.The smaller is the R4,the lower will be the gain.The low frequency roll off characteristics are decided by C3.
Voltage divider network comprising of R1,R2 and R5 provide a DC bias of about half the supply voltage R5 and C2 from a supply line filter to reduce the hum level as well as to reduce the chances “growling” when the preamplifier is operated from common power supply.
Circuit diagram with Parts list.
- Assemble the circuit on a good quality PCB or common board.
- Use mono sockets for connection input and output.
- The IC1 should be mounted on a holder.
- The supply voltage can be up to 24V DC .I prefer 12V DC.