Resistor R3 provides collector to base bias for Q1 and C3 is an AC by pass capacitor for the collector resistor R4. The audio input is coupled to the base of Q1 through resistor R1 and capacitor C1. Transistor Q1 with its associated components is wired as a pre amplifier stage. The circuit shown here is suitable for small radio receivers, audio players, intercom, telephone etc. Up to 78% efficiency is possible with class AB designs and cross over distortion is reduced. In class AB operation each output device conducts more than half of the input signal cycle. Description.Ī very simple and easy to build class AB audio amplifier using four transistors is shown here.
More over the value of the components are not very critical and slight variations in it will not affect the performance. The main feature of these circuits is that they all are just basic designs and the components used can be easily obtained from your junk box. These are circuits that can be used in a lot of low scale applications. A Low cost amplifier circuit using Transistor So you may keep visiting this post in future for more updates. This article is solely dedicated to publish more transistor amplifier circuits. Transformer X1 is a 230V primary to 9V-0-9V, 10A secondary used in reverse.This article is a list of various types of amplifier circuits built using Transistors alone.This includes a Class AB amplifier using 4 transistors, then we have a headphone amplifier circuit and finally a low power amplifier using transistor. Suitable heatsinks may be used for the output stage transistors. Somewhat higher wattage can be achieved by increasing the drive to 2N3055 transistors (by lowering the value of resistors R7 and R8 while increasing their wattage). This voltage can be used to heat your small electronic devices such as lamp, soldering iron, battery charger etc.
When you power the circuit using switch S1, transformer X1 produces 230V AC at its primary terminal. The centre-tapped terminal of the secondary of the transformer is connected to the battery (12V, 7Ah), while the other two terminals of the secondary are connected to the collectors of power transistors T7 and T8, respectively. The outputs from the drivers are fed to transistors T5 and T8 (2N3055) connected for push-pull operation.Ī 230V AC primary to 12V-0-12V, 4.5A secondary transformer (X1) is used. The complementary outputs from collectors of transistors T1 and T2 are given to PNP darlington driver stages formed by transistor pairs T3-T4 and T6-T7 (utilising transistors BD140 and 2N6107). For obtaining correct frequency, the values of resistors R3 and R4 may have to be changed after testing. Transistors T1 and T2 (BC548) form a 50Hz multivibrator. This is low cost fully transistorised power inverter 60W circuit capable of driving medium loads of the order of 40 to 60 watts using battery of 12V, 15 Ah or higher capacity.
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