Rangkaian 1,5V Earphones Audio Amplifier

This audio amplifier circuit, connected to 32 Ohm impedance mini-earphones, can detect very remote sounds. Useful for theatre, cinema and lecture goers: every word will be clearly heard. You can also listen to your television set at a very low volume, avoiding to bother relatives and neighbors. Even if you have a faultless hearing, you may discover unexpected sounds using this device: a remote bird twittering will seem very close to you.

Skema Rangkaian 1,5V Earphones Audio Amplifier

The heart of the circuit is a constant-volume control amplifier. All the signals picked-up by the microphone are amplified at a constant level of about 1 Volt peak to peak. In this manner very low amplitude audio signals are highly amplified and high amplitude ones are limited. This operation is accomplished by Q3, modifying the bias of Q1 (hence its AC gain) by means of R2.

A noteworthy feature of this circuit is 1,5V battery operation.
Typical current drawing: 7,5mA.

List Component

• P1: 22K Log. Potentiometer
• R1,R9: 10K 1/4W Resistors
• R2: 1M 1/4W Resistor
• R3: 4K7 1/4W Resistor
• R4,R7: 100K 1/4W Resistor
• R5: 3K9 1/4W Resistor
• R6: 1K5 1/4W Resistor
• R8: 100R 1/4W Resistor
• C1,C2: 100nF 63V Polyester or Ceramic Capacitors
• C3,C6: 1µF 63V Polyester or Ceramic Capacitors
• C4: 10µF 25V Electrolytic Capacitor
• C5: 470µF 25V Electrolytic Capacitor
• D1: 1N4148 75V 150mA Diode
• Q1,Q2,Q3: BC547 45V 100mA NPN Transistors
• Q4: BC337 45V 800mA NPN Transistor
• MIC1: Miniature electret microphone
• SW1: SPST Switch
• J1: Stereo 3mm. Jack socket
• B1: 1.5V Battery

Source

45 watt Amplifier kelas B

45 Watt Class B amplifier Circuit of this very simple , straightforward but Rugged circuit, though intended for any high quality audio applications and, above all, to complete the series of articles recently started forming the Modular Preamplifier Control Center, is well suited Also to make a very Good Guitar or Bass amplifier

Skema rangkaian 45 watt amplifier kelas B

Note

• Power transistors Q8 and Q9 Can be Used satisfactorily: 2N3055/MJ2955, TIP3055/TIP2955, TIP35/TIP36, MJ802/MJ4502 amongst others.
• Power transistors Q8 and Q9 Should be mounted on a black, finned heatsinks as usual.

Technical data:

• Output power (1KHz sinewave): 45 Watt RMS into 8 Ohms - 69W RMS into 4 Ohms
• Sensitivity: 0.81V RMS input for 45W output
• Frequency response @ 1W RMS: 15Hz to 23KHz -0.2dB
• Total harmonic distortion @ 1KHz: 1W 0.008% 20W 0.008% 45W 0.016%
• Total harmonic distortion @10KHz: 1W 0.01% 20W 0.015% 45W 0.025%
• Unconditionally stable on capacitive loads

List Component

• R1: 18K
• R2: 3K9
• R3,R6: 1K
• R4: 2K2
• R5: 15K
• R7: 22K
• R8: 330R
• R9,R10: 10R
• R11,R12: 47R
• R13: 10R/1 Watt
• C1: 1µF/63V
• C2: 470pF/63V
• C3: 47µF/25V
• C4: 15pF/63V
• C6: 220nF/100V
• C6: 100nF/63V
• D1,D2,D3,D4: 1N4148
• Q1,Q2: BC560C
• Q3,Q4: BC556
• Q5: BC546
• Q6: BD139
• Q7: BD140
• Q8: 2N3055
• Q9: MJ2955

source

Rangkaian 2 watt Amplifier BD139/140

This amplifier operates in Class AB mode with up to 2 watts of output power, the single 470R preset resistor controls the quiescent current PR1 flowing through the BD139/140 complimentary output transistors. Adjustment here, is a trade-off Between low distortion and low quiescent current. Typically, under quiescent conditions, current is about 15 mA, rising to 150 mA with a 50 mV input signal. The frequency response is shown below and is flat from 20Hz to 100kHz

Skema rangkaian 2 watt amplifier

PR1 470R controls the quiescent current flowing through the BD139/140 complimentary output transistors. Adjustment here, is a trade-off between low distortion and low quiescent current. Typically, under quiescent conditions, current is about 15 mA rising to 150 mA with a 50 mV input signal. The frequency response is shown below and is flat from 20Hz to 100kHz

This amplifier circuit is DC biased so that the emitters of the BD139 and BD140 are at approximately half supply voltage, to allow for a maximum output voltage swing. R9 and R10 provide a degree of temperature stabilization which works as follows. If the output transistors are warm, the emitter currents will increase. This causes a greater voltage drop across R9 and R10 reducing the available bias current. All four transistors are direct coupled which ensures:

• A good low frequency response
• Temperature and bias change stability.

Mini Amplifier IC LM380

Based amplifier IC's offer many advantages including high efficiency, high gain, low standby current, low component count, small size and, of course, low cost. It is little wonder that audio amp IC's have replaced most discrete transistors in consumer electronic devices. While many experimenters have stayed away from these little black Mysteries, I am going to uncover some of their secrets and demonstrate how easy they are to use

Rangkaian Amplifier IC LM380

Amplifier IC LM380 comes in two flavors; LM380 and LM380-8 with output powers of 700 milli-watts and 2 watts respectively. A schematic drawing below depicts the 8th and LM380-LM380.

Skema Rangkaian Amplifier IC LM380-8

Skema Rangkaian Amplifier IC LM380

The LM380-8 comes in an 8-pin package and its basic circuit is virtually identical to the LM380 except for the different pin out. The LM380 comes in a 14-pin package and pins 3,4,5,10,11 and 13 are connected to ground to act as a heat sink. Experience has shown the LM380 should be soldered directly to the circuit board (no IC socket) if it is going to be operated at its full rated output of 2 watts. This IC can become quite warm and it's important to get rid of excess heat through the pins. The primary advantages of the LM380 series IC's are higher output power, very low distortion and low external parts count.