The main amplifier 50 watt OCL by LF351-2N3055-MJ2955 with PCB
This main amplifier 50 watt OCL circuit has high quality and economical. Because it is designed simple, It can be easily created in your friends, An electronics rookie. And cheap when compared to other speakers, the as same volume level.
The main power amp.
This circuit is designed in such a way “Direct Coupling All Complementary IC Drive” will be seen that, the heart of the circuit is IC1(LF351), are the differential amplifier and pre driver circuit.
Note: I chose LF351, because the noise reduction circuit. And high frequency response than IC741, or you may use a number TL071 or NE5534N is good quality as well.
The output signal of IC1 pass through two diodes D1,D2(both is 1N4148) to the transistor drivers Q1(BD139),Q2(BD140). Then, their current is entered to two main transistor output Q3(MJ2955),Q4(2N3055).
The small Potentiometer VR2-1K is fined the idle current of this amplifier circuit that easy to fine who not has an amp meter to do not need measure the IDLE current, you just fine the VR2 at middle only (very simple!)
Instructions on how to create.
1. Check the completed of PCB that defective, short circuit or not.
2. First, do not connect to the output transistors(MJ2955,2N3055).
3. Use a voltmeter measure voltage at output speaker and ground point.
4. Supply to this circuit And must meter reading is zero volts. Or error must not exceed 0.5V.
5. put the output transistor into this circuit.
6. The voltage must be OV the same, If non-zero, indicating that the bad output transistors.
7. Connect speakers and input signal to this amplifier circuit. Let’s to listen the melodic music.
The Electronic parts.
ZD1,ZD2___15V 0.5W Zener diode
C1,C9____10uF 16V Electrolytic capacitors
C3,C4___47uF 25V Electrolytic capacitors
C2______100uF 16V Electrolytic capacitors
Holding the output transistors onto the heat sink you must sure that:
1. The screws tight, not fell, the loose easily.
2. Do not the short circuit between the collector Pin(transistor body) and heat sink, Due to the installation of mica insulation is not well.
And….. This circuit may be good for you!
65W Amplifier Class AB by LF351 ,TIP3055 and TIP2955
I like mini power amplifier less 100W because it is low cost nad easy to make project. The 65W Amplifier Class AB,I use main part electronics are IC LF351 and thansisror two part TIP3055 and TIP2955. The LF351 is a low cost high speed JFET input operational amplifier.
The TIP3055 and TIP2955 are small size but have high power. This is circuit want Voltage supply +38V and -38V at current 3A min. Have output power 65W to 75W at 8ohm speakers.
Power Amp OCL 70w With IC 741, 2N3055
Younger brothers and sisters a student takes an interest to build electronics project sends a teacher. I then choose this circuit , because build easy be valuable certainly. It is Main Power Amplifier Circuit 70Watt RMS sizes are model OCL Class AB. Use pillar equipment be IC 741 and Transistor 2N3055,MJ2955 a little this equipment circuit. If friends want get electric tall power about 70Watt should use Voltage Supply +38V , and -38V. The usability should fine VR1 be appropriate. Request a friend has fun to listen the music from Amp Circuit , please sir.