Sunday, May 28, 2017

Simple Microphone Amplifier Circuit using Transistor

Electronic Kit School. - There are many electronic circuit that design to get sensitive sound pick-up in this time. All circuit mentioned aim to result best design and allow us to use this circuit 

There are electronic design circuit to build simple microphone amplifier using Condenser Microphone (CM) will give the sensitive sound. One of the simple microphone amplifier circuit is look like in Figure 1 below with the main component used are CM and transistors that popular today.

In this time, beside we will show you the circuit, here we also will show you component part and global description about this circuit.


  1. R1 1.2
  2. R2 2.7 KΩ
  3. R3 33 KΩ
  4. R4 6.8 KΩ
  5. R5 3.3 KΩ
  6. R6 100
  7. R7 560 KΩ
  8. R8 4.7 KΩ
  9. R9 10 KΩ
  10. VR1 1 KΩ
  11. T1 BC149C
  12. T2 BC147B
  13. C1 47μ  10V
  14. C2,C3 0.1μ
  15. C4 220μ  10V
  16. C5 10μ
  17. BATT 6VOLT Battery
  18. MIC Condenser Microphone

Circuit like in Figure 1 above show you about the microphone amplifier using the main component Cm and transistors. From Electronicsproject site describe that the circuit diagram you can see that microphone is employs as the transducer. The output of the condenser microphone is quite low it has to connect with an FET amplifier. This amplifier circuit is power by the R1,R2 resistor network. The output of condenser microphone is fed to a two-stage amplifier. Transistor T1 (BC149C) utilise current series feedback the first stage. The second stage comprising transistor T2 is connected in the voltage shunt feedback configuration. These two stages provide sufficient gain to pick up even the slightest whisper. The amplifier circuit in the site requires  4.2 volt supply which can be obtained with a resistor R9 [1k]. 

The value of this resistor may be altered to suit a supply voltage other than 6 volts. Output of the microphone amplifier can be made variable by connecting a 10k potentiometer as shown in the circuit. Circuit‘s gain can be increased by reducing the value of R6 to 47 ohms or 22 ohms. depending on the input sensitivity of the main amplifier system. Increase in gain was also observed by using 3V supply and eliminating R9 altogether. The microphone should be housed in a small round enclosure.

Monday, May 22, 2017

Engineering Book: High Voltage Engineering Fundamentals 2nd Edition by John Kuffel - Free Download E-book

ElectronicKitSchool. - This is one of basic voltage engineering book categorize that titled with High Voltage Engineering Fundamentals, Second Edition 2nd Edition that authored by John Kuffel (Author), Peter Kuffel.

Image Courtesy of Free Engineering Books
This article will show you the reviewing of High Voltage Engineering Fundamentals, Second Edition like book description and table content. The last in this article we also will give you link to take download e-book of High Voltage Engineering Fundamentals 2nd Edition by John Kuffel freely.


From describe that Power transfer for large systems depends on high system voltages. The basics of high voltage laboratory techniques and phenomena, together with the principles governing the design of high voltage insulation, are covered in this book for students, utility engineers, designers and operators of high voltage equipment.

In this new edition the text has been entirely revised to reflect current practice. Major changes include coverage of the latest instrumentation, the use of electronegative gases such as sulfur hexafluoride, modern diagnostic techniques, and high voltage testing procedures with statistical approaches.

Features of Contents:

  1. Electric stress estimation and control using various techniques.
  2. Mechanism of breakdown of gases, liquids and solid insulating materials.
  3. Application of insulating materials for different electrical equipment’s.
  4. Generation of high a functional.c., d.c. and impulse voltages and currents for testing of electrical equipment’s.
  5. Various techniques and circuits for measurements of high voltages.
  6. Testing procedures for testing of insulators, cables, transformers, circuit breakers etc.
  7. High voltage schering bridge and partial discharge measurement techniques for assessing life-span of equipment’s.
  8. Insulation coordination and over voltage protection.
  9. A few photo plates to supply physical feel of various equipment’s within a high voltage laboratory.
  10. Large quantity of solved examples, practice problems and multiple choice issues and answers.

Download E-book

Here, we provide you some the links to download e-book of High Voltage Engineering Fundamentals 2nd Edition by John Kuffel from external server. So, if you fail to use one link or the link broken you can choose other link to download it. Please click the icon below to start downloading.

High Voltage Engineering Fundamentals 2nd Edition by John Kuffel

Saturday, May 6, 2017

Light Dimmer Circuit using Triac and Diac

Electronic Kit School. - In electronic field there are many project with simple and expert circuit to give easily maintenance light dimmer. Using simple or complex component light dimmer can be built.

In here we will show you one of the simple light dimmer circuit using triac and diac component that control the lamp or light with rotate potentiomenter. The circuit mentioned look like shown in Figure 1 below.

The main component to build this circuit are triac and diac which popular today. In this time, beside we will show you the circuit, here we also will show you component part and global description about this circuit.


Figure 1. Circuit of Light Dimmer using Triac and Diac (Source:

Component Parts
  1. R1 = 68 KΩ
  2. R2 = 270 Ω
  3. R3 = 10 KΩ
  4. VR1 = 100 KΩ
  5. VR2 = 500 KΩ
  6. C1, C2, C3 = 0.33 µF/400V
  7. TR1 = Triac BT136
  8. D1 = Diac ER900

Circuit like in Figure 1 above show you about the light dimmer circuit using triac and diac. From Electronicsproject site describe that the basic principle of light dimmer is based on phase control. The variable resistor VR2 is main controller of the circuit Light Dimer. From main supply capacitor C2 get charges which trigger DIAC D1. VR1 is used for fine brightness controller which control brightness to lower level. R2 and C3 used to overcome interference problem.

As the The lighting source (i.e. bulb, tube light) glow according to their specified watt rating. If we need more light then we have to use high watt bulb at the same place if we need low light we have to replace high watt bulb with low rating. But What if there is not necessary to change i.e. different brightness obtained from same source. Here is the simple but effective project which control brightness according to our use from the unchanged light source.