Transistor schematic7/28/2023 With the help of the following transistor amplifier circuit, one can get an idea about how the transistor circuit works as an amplifier circuit. Transistor as an Amplifier CircuitĪ transistor can be used as an amplifier by enhancing the weak signal’s strength. If you would like more information about identifying components and building up circuits, please see my article “ What You Need to make the Electronic Circuits at Bright Hub.The parameters of a good transistor mainly include different parameters namely high gain, high slew rate, high bandwidth, high linearity, high efficiency, high i/p impedance, and high stability etc. T11, T14 = 2N3055 (Mount over large finned-type heatsink)įuse, Mains Cord, Metallic Enclosure, Switch, External Sockets etc. T13 = BD139 (Mount over “C” channel heatsink) T10 = BD140 (Mount over “C” channel heatsink) You will require the following parts to build this 100w transistor power amplifier schematic design.Īll resistors are 1/4w, CFR unless otherwise specified. The current consumption may shuffle in between 1 and 3 Amp depending on the volume level of the unit. The output inductor L1 is made by winding 20 turns of 0.8 mm super enameled copper wire right over the resistor R24. The output stage of the circuit is virtually unaffected by temperature variations, however ideally T8, T9 and T7, T12 may be coupled with each other (by gluing them together) to enhance thermal stability of the circuit. Preferably use separate heatsinks for the transistors T10, T11, T13, T14, to avoid the involvement of messy mica isolators, heatsink paste, etc. Important Technical Parameters to be FollowedĪlthough the circuit parameters are not critical and may be built over a general purpose board, care should be taken that the component layout does not differ from the circuit diagram by much. The quiescent current can be set through P1 with a digital multimeter connected across resistors R6 and R7.Īdjust P1 until the meter reads about 40 mV, corresponding to 50 mA current. The frequency characteristics lie in between 1 dB from 15 Hz to around 100 kHz.ĭue to its very high amplification factor of around 20,000, the output stage may have an ideally low quiescent current drain of about 40 mA. The input sensitivity is in the vicinity of 750 mV. Total harmonic distortion is less than 0.01 %.įrequency range is within 20 Hz and 20 kHz. Power output is 60 watts into 8 Ω and 100 watts into 4 Ω loudspeaker. The remaining portion of the circuit is mainly the output stage and is responsible for amplifying the differential stage into the loud speakers. Transistor T1 and T2 are wired up in a standard differential amplifier mode. The presence of R2 and C2 ensures no frequency above 250 KHz makes its way into the circuit, thus blocking most of the high frequency RF intrusions. C1 also functions as an input stage DC bias isolator. R1 and R2 fix the input impedance, and the inclusion of C1 creates a high-pass filter that blocks all frequencies around 1.5 Hz. The input stage employs the standard R/C filter configuration. Transistors T9, T10, T11 and T12, T13, and T14 form two well-balanced halves of the circuit, perfectly complementing each other. However a closer look will prove this wrong. Circuit DescriptionĪt the first glance the circuit rather appears to be unsymmetrical in design, due to an unbalanced looking output stage. I have personally tested this circuit and believe me its response is outstanding, build a couple of them and it becomes compatible with stereo inputs- that also means now you are producing 200 watts of brain-pounding music power. If all the connections are done accurately as shown in the diagram, the circuit should immediately start “pumping” your loud speakers with a high quality music output. The entire circuit utilizes commonly available components and may be simply built over a general purpose board. If we compare the simplicity of the proposed 100w transistor power amplifier schematic design to its power output, which is a good 100 watts, indeed it looks very impressive.
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