The datasheet for a lousy old 741 opamp shows that its minimum output current is only about 5mA (10V into 2k ohms) and its maximum allowed supply voltage is 36V. Its minimum output swing with a 30V supply is only 20V p-p.
The datasheet for a 2N3055 transistor shows that its minimum peak output current with an peak input of only 5mA is 355mA.
The 355mA is the peak minimum output current. The RMS minimum output current will be 251mA. Then the minimum output power into an 8 ohm speaker will be (251mA squared) x 8 ohms= 0.5W like a cheap clock radio. The output swing will be 5.7V p-p.
1000W RMS into an 8 ohm speaker has a voltage swing of 253V p-p and a peak current of 15.8A. 2N3055 transistors have a maximum supply voltage of only 60V so they cannot be used. But many 2N3055 transistors can be paralleled and produce 60V p-p and a peak current of 95A to drive a transformer that steps up the output voltage to 5kV.
A 741 opamp was designed 46 years ago. It is too noisy for audio and it has trouble above only 9kHz. The 2N3055 transistor is also very old and is not used for audio amplifiers today.
if one 2n3o55 give 60V so we can use many in series to get more voltage???? actually this is not related to audio amplifier i'm working on an inverter.
i've used 3 stages of op amp with voltage gain of round about 400 and current is 5mA. so what should i do to enhance the current which is going to feed into 2n3055 circuitry?? i want 1000W and 1000 volts before power transformer
60V means maximum voltage which 2n3055 can bear m i right?? current from 2n3055 is 15 amp then what to do to get 1 amp current with above mention power and voltage??
An old inverter had a square-wave output. But many modern electronic devices need a sine-wave output. You are thinking about using a linear amplifier to amplify a sine-wave to make an inverter but you do not understand that the linear transistors will get extremely hot and waste a lot of battery power by making heat.
Therefore a modern inverter uses a high frequency Pulse-Width-Modulation (PWM) circuit to make a sine-wave with many steps. The carrier frequency is high so that a small lightweight ferrite core transformer is used. The transistors simply switch on and off without getting hot. The stepped sinewave is easily filtered into a good smooth sinewave.
help help
Posted - Apr 23 2014 : 04:41:24 AM
