DIY a Basic Common Emitter Amplifier for School Studying



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The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. The common-emitter amplifier is designed so that a small change in voltage (Vin) changes the small current through the base of the transistor; the transistor's current amplification combined with the properties of the circuit means that small swings in Vin produce large changes in Vout. From mobile phones to televisions, vast numbers of products include amplifiers for sound reproduction, radio transmission, and signal processing and more...

Step 1: Step 1: Solder the Resistors to the PCB

Resistors do not have polarity, just insert them into the PCB and then solder. Please note that you should get them at the right place that conform to the value printed on the PCB. Or it won’t be working properly. I recommend to use a multimeter to verify the resistor before you do the job.

Step 2: Step 2: Solder the Ceramic Capacitor and 8050 NPN Transistor to the PCB

Insert the 102 ceramic capacitor and 8050 NPN transistor into the respective place on the PCB as shown by the image④. Please note that the flat side of the transistor should be at the same side of the diameter of the semicircle printed on the PCB. When everything has gotten ready then solder them and cut off excess legs from the components.

Step 3: Step 3: Solder the Electrolytic Capacitors to the PCB

Electrolytic capacitors have polarity that you should verify their polarity before inserting them into the PCB. The long leg is anode while the short leg is cathode, or the leg near the white color band cathode and the other is anode. The value of the electrolytic capacitors are printed on their bodies. You just need to check the value and insert them to the place respectively has the value printed on the PCB.

Step 4: Step 4: Solder the Pin Headers to the PCB

The short end of pin header should be insert into the PCB and the long end is left for the header connector for the extended module or debugging purpose.

Step 5: Step 5: Solder the Potentiometer to the PCB

The legs of the potentiometer are crooked by default. You should put the three legs into the respective hole on the PCB and then carefully press the potentiometer into the holes.

Step 6: Step 6: Operate the Amplifier

The input signal is a sine wave generated by a NE555 circuit made in this instructable(please right click this link for reference). And the recommended working voltage of this common emitter amplifier is about 12V. By adjusting the potentiometer to change the bias voltage of the transistor you will get different waveforms with diffenent amplitude as shown in the pictures. This DIY kits is ideal for students and hobbyists to learn about the knowledge of amplifier. This DIY kits is available at



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