Simple Pre-Amp with One Transistor

This is a very simple pre-amp circuit which use a transistor as a active component to boost the input signal. Its simplicity makes this circuit easy to built and inexpensive. The microphone used in this circuit is electret type which is very sensitive detecting the sound around its.

Mini Micropone Amplifier Circuit

This is the schematic diagram of mini microphone amplifier circuit, which all of the active components are based on transistor. This circuit project is called "mini" since its size is small and the output is small too. It uses surface mount technology.

Circuit works

Electric Guitar Preamplifier Circuit based TL071

Right here is definitely the circuit of a electric guitar preamplifier circuit based TL071 that would accept any common guitar pickup. It's also versatile in that it has two signal outputs.

A common illustration of working with a pickup attached to a guitar headstock is shown in above image. The pickup unit contains a transducer on one end and also a jack on the other end. The jack can be plugged right into a guitar preamplifier circuit and then to a power amplifier system.

Mini Mic Pre-Amplifier Circuit based IC LM358

The following diagram is a easy to build, simple and low cost mic pre-amp circuit which build using op-amp chip of LM358.

Component Parts List:
R1, R3, R4 = 10K
R2 = 1K
R5 = 100K-1M Potensiometer
C1 = 0.1uF
C2 = 4.7uF/16V
IC1 = LM358 dual op-amplifier
Mic = Electret Microphone

Notes:

• Vary the variable resistor of R5 to adjust the gain of op-amplifier IC LM358.
• The LM358 has two op-amp module, you may build stereo audio pre-amplifier using single LM358.

Need a reference for LM358? Then download LM358 datasheet

Simple Audio Pre-Amp circuit

Designed based on single Transistor 2N3904, this circuit will provide good gain for weak audio signals such as electret microphone. Easy to build and really simple for pre-amp circuit.

Pre-amp circuit with tone control

This a 2 in 1 circuit where 2 modules joined in one circuit. With this circuit, you no longer use tone control circuit before your amplifier, but you can add an equalizer between this circuit and your amplifier circuit. In this circuit, P1 is used to control the volume level, P2 to control Bass level and P3 controls Treble level.

This is a mono channel circuit, you need to build another equal circuit to make this circuit has stereo channel.

Part List:

R1__________220K 1/4W Resistor
R2__________100K 1/4W Resistor
R3__________2K7 1/4W Resistor
R4,R5_______8K2 1/4W Resistors
R6__________4K7 1/4W Resistor
R7,R8,R13___2K2 1/4W Resistors
R9__________2M2 1/4W Resistor
R10,R11_____47K 1/4W Resistor
R12_________33K 1/4W Resistor
R14_________470R 1/4W Resistor
R15_________10K 1/4W Resistor
R16_________3K3 1/4W Resistor (See Notes)

C1,C2,C9____470nF 63V Polyester Capacitors
C3,C4_______47nF 63V Polyester Capacitors
C5,C6_______6n8 63V Polyester Capacitors
C7__________10µF 63V Electrolytic Capacitor
C8,C10______22µF 25V Electrolytic Capacitors
C11_________470µF 25V Electrolytic Capacitor

Q1,Q3_______BC550C 45V 100mA Low noise High gain NPN Transistors
Q2__________2N3819 General-purpose N-Channel FET

Condenser Mic preamplifier

This is a very simple preamplifier circuit for condenser microphone. This mic preamplifier also can be used for dynamic microphone.

You can replace the BC549 with BC109C. For better audio result, use ultra low noise transistor BC650C.