Monday, April 05, 2010

Rangkaian 60 Watt Power Amplifier

Audio Power Amplifier 60 Watt

This amplifier is very simple to build, uses commonly available parts and is stable and reliable, this amplifier most were operated as small PA or instrument amps, but many also found their way into home hi-fi systems. The amp is capable of driving 4 Ohms, but it is starting to push the limits of the transistors, however, even when used at 4 Ohms, very few failures were encountered.

Rangkaian 60 Watt Power AmplifierSkema Rangkaian 60 Watt Power Amplifier

  • The resistor values are not too critical, but if 1/2W metal film resistors are used throughout, this will help to reduce noise.
  • The 0.5 Ohm resistors need to be 5W wirewound types.

If you want to build it, see P3A, Layout is not especially critical, and in fact if the components are laid out on a board much as they are seen in the diagram, you should have no problems. 3 Amp fuses should be fitted to each supply rail - these will not prevent output transistors from failing with a shorted speaker lead, but they will prevent further damage (wiring melting, transformer burning out, PCB catching on fire, etc).

The input capacitor should be a polyester type. If an electrolytic is to be used, the positive end goes to the amplifier (there is about +230mV on the bases of the long tailed pair transistors).

When wiring, ensure that the feedback connection is taken from the speaker output terminal, immediately before the inductor. Any track which is carrying half-wave audio from one or the other power transistor resistors will cause distortion of the feedback signal, degrading sound quality.



Rangkaian 150 Watt OCL Amplifier

150 Watt OCL Power Amplifier

If you are fanatical about the use of transistors jengkol 2N3055 and MJ2955 then this circuit is the answer. This OCL power amplifier circuit deliver a blasting 150 watt to a 4 Ohm speaker. The amplifier circuit is very cheapest and can be powered from 24 to 32 V/5A dual power supply. You must try this circuit. Its working great. Because Transisitor on the final amplifier will be very hot then add the aluminum finned cooler and the fan so that the transistor is not too high temperatures

Rangkaian 150 Watt OCL Amplifier
Skema Rangkaian 150 Watt OCL Amplifier

  • Use a well regulated and filtered power supply.
  • Connect a 50K POT in series with the input as volume control if you need.Not shown in circuit diagram

The transistor 2N3055 NPN and MJ2955 PNP are a silicon Epitaxial-Base Planar transistor mounted in Jedec TO-3 metal case. It is intended for power switching circuits, series and shunt regulators, output stages and high fidelity amplifiers.

maximum rating Transistor 2N3055 NPN and MJ2955 PNP
  • Collector-Base Voltage : 100 V
  • Collector-Emitter Voltage: 70 V
  • Collector-Emitter Voltage: 60 V
  • VEBO Emitter-Base Voltage: 7 V
  • IC Collector Current: 15 A
  • IB Base Current: 7 A
  • Total Dissipation: 115 W
  • Storage Temperature: -65 to 200 oC
  • Tj Max. Operating Junction Temperature 200 oC


Sunday, April 04, 2010

Rangkaian Amplifier 300 Watt

Amplifier 300 Watt

Jul 2003 OnSemi released a new range of transistors, designed specifically for audio applications. These new transistors have been tested in the P68, and give excellent results. As a result, all previous recommendations for output transistors are superseded, and the new transistors should be used.

The transistors are MJL4281A (NPN) and MJL4302A (PNP), and feature high bandwidth, excellent safe operating area, high linearity and high gain. Driver transistors are MJE15034 (NPN) and MJE15035 (PNP). All devices are rated at 350V, with the power transistors having a 230W dissipation and the drivers are 50W.

Rangkaian Amplifier 300 WattSkema rangkaian amplifier 300 watt

  • The total DC is over 110V and can kill you.
  • The power dissipated is such that great care is needed with transistor mounting..
  • The amplifier circuit is NO SHORT CIRCUIT PROTECTION. The amp is designed to be used within a subwoofer or other speaker enclosure, so this has not been included. A short on the output will destroy the amplifier.
  • Transistor MJL4281A and MJL4302A are new most constructors will find that these are not as easy to get as they should be. The alternatives are MJL3281/ MJL1302 or MJL21193/ MJL21194.
All three driver transistors (Q4, 5 & 6)must be on a heatsink, and D2 and D3 should be in good thermal contact with the driver heatsink. Neglect to do this and the result will be thermal runaway, and the amp will fail. For some reason, the last statement seems to cause some people confusion - look at the photo below, and you will see the small heatsink, 3 driver transistors, and a white "blob" (just to the left of the electrolytic capacitor), which is the two diodes pressed against the heatsink with thermal grease.


Skema Rangkaian Elektronika