Saturday, July 28, 2012

Feed Back Power Amplifier

This concept has showed up lengthy returning in Realistic Gadgets a UK centered Journal. Based on this concept I designed this routine during 1981 to 1986 with lots of field tests and variations, the style was freezing in 1986. I have constructed so many amps for me and for my friends centered on this style with various energy levels. They are still throwing in so many homes. This concept can be used to any current firm also. You must pay attention to believe the superior booming bass sounds reaction. superior mid and hi wavelengths. Excellent temporary reaction with very low frame distortions. Hope you people  will enjoy the duplication of this firm.

In the art of audio sound duplication it is well-known that the powerful presenter is more nonlinear and produces more frame distortions than all the other program elements mixed. This is particularly true at low wavelengths which need large spool adventures where the rigidity of both the inner examine and the external encompass improves quickly as the spool techniques its optimum displacement, leading to a nonlinear revocation conformity producing great frame distortions.
For example, in a common great constancy stereo audio at a consistency of about 35 Hz the complete harmonic frame distortions of the firm might be of the order of 0.01%, whereas the frame distortions of the presenter might range from about 3.0% to about 50.0%, based on the volume. If this spool movement can be thought and given as a nourish returning to the previously level of the firm, this frame distortions can be reduced considerably.

Motional Reviews (MFB) was a audio speakers developed in the early Seventies by Philips Netherlands. It presented a feedback program to the woofers of HiFi audio speakers, allowing them to achieve a more prolonged low consistency reaction in a relatively small fencing. The key benefits are a very managed bass sounds reaction. Any frame distortions caused by the fencing or the woofer itself is instantly repaired by the feedback. These hand-built audio speakers were appearing excellent and were quite expensive.

As a different strategy, instead of using the spool activity, the present circulation through the speech can be thought (the present is proportionate to spool movement) and can be used as a spool activity feedback. This novel concept is used in this firm style (I don’t declare any originality; this concept has showed up in Realistic Gadgets UK Journal – lengthy returning – They might have even trademarked it).

The firm used here is a traditional Philips audio program routine, with a requirements of 40 W RMS @ < 0.06% Total Harmonic Distortion into 8 ohms impedance presenter and having a consistency reaction from 20Hz to 100 KHz, appropriately improved for our program.

The firm is a traditional category B immediately paired quasi free of charge out put level, managing with single 56Volt provide (no need for a managed or double energy supply). BC157 is the pre-driver and 50 percent provide backing. BD 139 is the car owner, a BD139 and a BD140 free of charge couple out put car owner level with 2N3055 as final out put level. The presenter speech coils present is thought through 0.47 ohms level of resistance linked from presenter one end to ground. This indication is given as negative fed returning to past level through 470 ohms. The 50 percent provide at presenter combining capacitor can be improved by different the 39K level of resistance (if required you may fix a 100K pre set in the place of 39K and modify for 50 percent provide with no in put indication at jct of both 0.47 ohms of out put transistors and presenter combining capacitor). The quiescent present through outcome transistors can be improved with 22 ohms in sequence with two prejudice diodes 1N4007. The value for 50mA quiescent present will lie between 15 to 33 ohms for a provide of 56volts. The firm can be secured with a simple 1.5Amp fast performing blend in the positive energy.

The firm can be constructed on 40watt Philips firm program panel or on any traditional simply immediately line panel. All the three car owner transistors need chilling segments. (Standard TO220 covering chilling fins). Out put transistors need a top quality extruded metal warm mess up with insulation increasing kit and with a apply of rubber conductive oil, permanently conductance of warm.

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