Wiring & diagram Info: preamplifier

Monday, January 26, 2015

Stereo Preamplifier With Bass Boost

This preamplifier was designed to cope with CD players, tuners, tape recorders etc., providing an ac voltage gain of 4, in order to drive less sensitive power amplifiers. As modern Hi-Fi home equipment is frequently fitted with small loudspeaker cabinets, the bass frequency range is rather sacrificed. This circuit features also a bass-boost, in order to overcome this problem. You can use a variable resistor to set the bass-boost from 0 to a maximum of +16dB @ 30Hz. If a fixed, maximum boost value is needed, the variable resistor can be omitted and substituted by a switch.

Stereo Preamplifier With Bass Boost Circuit diagram:

Parts:
P1 = 10K
P2 = 100K
R1 = 100K
R2 = 100K
R3 = 15K
R4 = 10K
R5 = 22K
R6 = 15K
R7 = 1K
R8 = 470R
C1 = 2.2uF-25v
C2 = 2.2uF-25v
C3 = 470uF-35v
C4 = 1uF-35V
C5 = 2.2uF-25v
C6 = 47nF-63v
C7 = 22uF-25v
IC1 = TL072, Opamp
SW1 = DPST Switch
Notes:

Schematic shows left channel only, but R1, R2, R3 and C1, C2, C3 are common to both channels.
For stereo operation P1, P2 (or SW1), R4, R5, R6, R7, R8 and C4, C5, C6, C7 must be doubled.
Numbers in parentheses show IC1 right channel pin connections.
A log type for P2 ensures a more linear regulation of bass-boost.
Needing a simple boost-in boost-out operation, P2 must be omitted and SW1 added as shown in the diagram.
For stereo operation SW1 must be a DPST type.
Please note that, using SW1, the boost is on when the switch is open, and off when the switch is closed.

Wednesday, November 12, 2014

VHF RF Single Chip Preamplifier circuit with explanation

Here is a high performance RF amplifier for the entire VHF broadcast and PMR band (100-175 MHz) which can be successfully built without any special test equipment. The grounded-gate configuration is inherently stable without any neutralization if appropriate PCB layout techniques are employed. The performance of the amplifier is quite good.
The noise figure is below 2 dB and the gain is over 13 dB. The low noise figure and good gain will help car radios or home stereo receivers pick up the lower-power local or campus radio stations, or distant amateur VHF stations in the 2-metres band. Due to the so-called threshold effect, FM receivers loose signals abruptly so if your favourite station fades in and out as you drive, this amplifier can cause a dramatic improvement.
The MAX2633 is a low-voltage, low-noise amplifier for use from VHF to SHF frequencies. Operating from a single +2.7 V to +5.5V supply, it has a virtually flat gain response to 900 MHz. Its low noise figure and low supply current makes it ideal for RF receive, buffer and transmit applications. The MAX2633 is biased internally and has a user-selectable supply current, which can be adjusted by adding a single external resistor (here, R1). This circuit draws only 3 mA current.

VHF RF preamplifier circuit diagram

Besides a single bias resistor, the only external components needed for the MAX2630 family of RF amplifiers are input and output blocking capacitors, C1 and C3, and a VCC bypass capacitor, C2. The coupling capacitors must be large enough to contribute negligible reactance in a 50-Ω system at the lowest operating frequency. Use the following equation to calculate their minimum value:
Cc = 53000/ flow [pF]

Saturday, September 13, 2014

Wednesday, September 10, 2014

Microphone Preamplifier

This is a good pre-amplifier for microphones that can be. Used in, for example, mixing consoles The circuit operates with a dual op-amp type NE 5532. The amplifier must be adjusted. Simply plug the power and control over P1 such that half the supply voltage (6 V) on pin 3 of IC1 state. P2 is then adjusted to the desired volume.

R1 = 8,2 kW
R2, R4, R5, R6 = 10 kW
R3 = 1 k
P1 = 4.7 K?
P2 = 100 k
C1, C2, C4, C6 = 10 uF
C3 = 470 nF
C5 = 100 nF
IC1 NE = 5532

Sunday, August 31, 2014

Phonon Preamplifier Circuits Wiring diagram

In recent years, following CDs introduction, vinyl recordings are almost disappeared. Nevertheless, a phonon preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient schema devised for cheap moving-magnet cartridges, can be used in connection with the audio power amplifiers shown in these webpages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency transients behavior due to passive equalization in the 1 to 20KHz range. Transistors and associated components provide ±18V supply to the op-amp, improving headroom and maximum output voltage.

Phono Preamplifier Circuits Diagram

Notes:

R2, R3, R4, R7, R8, C4 & C5 should be low tolerance types.
Schematic shows left channel and power supply.
For stereo operation R1, R2, R3, R4, R7, R8; J1; C1, C4 & C5 must be doubled.
Numbers in parentheses show IC1 right channel pin connections.

Technical data:

Sensitivity @ 1KHz: 2.5mV RMS input for 200mV RMS output
Max. input voltage @ 1KHz:120mV RMS
Max. input voltage @ 10KHz:141mV RMS
Max. input voltage @ 20KHz:127mV RMS
Frequency response @ 1V RMS output: 100Hz to 20KHz ±0.5dB; -0.75dB @ 30Hz
Total harmonic distortion @ 1KHz and 6V RMS output: 0.006%
Total harmonic distortion @10KHz and 1V RMS output: 0.02%

Parts:

R1_________47K1/4W Resistor

R2________100R1/4W Resistor

R3__________6K81/4W Resistor

R4_________68K1/4W Resistor

R5,R6_______2K71/4W Resistor

R7__________2K21/4W Resistor

R8_________39K1/4W Resistor

C1-C3_____100µF25V Electrolytic Capacitors

C4,C5______47nF63V Polyester Capacitors 5% tolerance

D1,D2__BZX79C1818V 500mW Zener Diodes

IC1_______LM833Low noise Dual Op-amp

Q1________BC33745V 800mA NPN Transistor

Q2________BC32745V 800mA PNP Transistor

J1__________RCAaudio input socket

Saturday, August 9, 2014

Balanced Microphone Preamplifier

The preamplifier is intended for use with dynamic (moving coil–MC) microphones with an impedance up to 200 Ω and balanced terminals. It is a fairly simple design, which may also be considered as a single stage instrument amplifier based on a Type NE5534 op amp. To achieve maximum common-mode rejection (CMR) with a balanced signal, the division ratios of the dividers (R1-R4 and R2-R5 respectively) at the inputs of the op amp must be identical. Since this may be difficult to achieve in practice, a preset potentiometer, P1, is connected in series with R5. The preset enables the common-mode rejection to be set optimally. Capacitor C1 prevents any direct voltage at the input, while resistor R7 ensures stability of the amplifier with capacitive loads.

Circuit diagram:

Balanced Microphone Preamplifier Circuit Diagram

Power supply:
Power_Supply_Balanced_Microphone_Preamplifier_Circuit_Diagramw

Power Supply For Balanced Microphone Preamplifier

Resistor R3 prevents the amplifier going into oscillation when the input is open schema. If the microphone cable is of reasonable length, R3 is not necessary, since the parasitic capacitance of the cable ensures stability of the amplifier. It should be noted, however, that R3 improves the CMR from >70 dB to >80 dB. Performance of the preamplifier is very good. The THD+N (total harmonic distortion plus noise) is smaller than 0.1% with an input signal of 1 mV and a source impedance of 50 Ω. Under the same conditions, the signal-to-noise ratio is –62.5 dBA. With component values as specified, the gain of the amplifier is 50 dB (´316). After careful adjustment of P1 at 1 kHz, the CMR, without R3, is 120 dB. The supply voltage is ±15 V. The amplifier draws a current at that voltage of about 5.5 mA. Note the decoupling of the supply lines with L1, L2, C2–C5.

Monday, January 26, 2015

Stereo Preamplifier With Bass Boost

Wednesday, November 12, 2014

VHF RF Single Chip Preamplifier circuit with explanation

VHF RF preamplifier circuit diagram

Saturday, September 13, 2014

ECM Mic Preamplifier

Wednesday, September 10, 2014

Microphone Preamplifier

Sunday, August 31, 2014

Phonon Preamplifier Circuits Wiring diagram

Technical data:

Parts:

Saturday, August 9, 2014

Balanced Microphone Preamplifier