Very Low Noise Pick-up Preamplifier


Posted on Mar 12, 2013

The preamplifier was designed to signal sources such as low-impedance moving coil cartridges (MC) on turntables high fidelity (and yet still there). The impedance of the amplifier is 100 W. To keep the noise levels low, three double-type transistors MAT03 SSM2220 or linked together to form a differential amplifier. Connecting this amp in front of an operand (OR27) is reduced to very low levels in noise input of the latter. The connections of the bases of the amplifier's inputs act as `super operator` very low noise input. One advantage of pnp transistors compared with the corresponding npn is much lower noise low frequencies. On the other hand, creates a relatively high current polarization at the entrance, about 5.5 Ma, as effect of the regulation of 2 mA for each transistor in combination with the relatively low gain transistor pnp.


Very Low Noise Pick-up Preamplifier
Click here to download the full size of the above Circuit.

The trimmer R 1 and resistance A7/A8 offset tolerances of the A4 and A5 at the exit of the differential amplifier. The tranxistor T4 LED D1 and the power source for forming the differential amplifier. The D1 is flat red LED's mounted on the T4 for better thermal coupling. Because thorythoW entry of the order of 0.4 nV / (Hz) (theoretical resistor value for 1I, Z) is an important feedback to grow as little as possible the total picture noise. Therefore the impedance of the feedback circuit should be much less than 1O W. In contrast, one needs OR27 specified minimum load impedance that can not be less than 600 ohms, so the price feedback resistance is less than 600 W. To ensure low prices for the A9 should be someone compromise the value of the maximum gain (about 24 dB, or 15.7 times in our case). Fitting extra resistance, R11, ahead of feedback operational amplifier that does not clutter while adding A9 only 0.3 nV / (Hz) 1 / 2 noise input, which in fact based on the measured data is 0.52 nV / (Hz) 1 / 2. If you want higher profits, can be image noise 0.4 nV / (Hz) 1 / 2 with a lower price for the R9.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Solid state stepping switch
op amp 6 line audio mixer circuit
radio remote control
A solar battery charger
An Ionisation Chamber Shield for OpenRelief
TBA820M high gain audio amplifier circuit design electronic project
Telegraph Transmitter in the Pilot Radios Radio Design magazine 1930s
Stepper Motor Project
MA1576Y charge pump LED driver circuit diagram
Combustible gas alarm circuit diagram 2 7806 KD28
Gas flameout alarm circuit



Top