Power amplifier electronic circuits-tube audio rf amplifiers

Electronic Amplifier Circuits-Power amplifier, audio amplifier designs and circuits

May 31st, 2010

Simple Function Generator Circuit

Circuit Description

Here is the circuit diagram of common function generator circuit. The central part of this circuit is the function generator IC ICL 8038. This function generator IC can generate waveforms such as sine, square and triangular at the same time. This IC has got an added feature that it can control the waveform parameters such as frequency, duty cycle and distortion. The frequency of the output waveform is adjusted using potentiometer R7 (100K). The potentiometer R3 (1K) is used for adjusting the duty cycle of the waveforms. Adjustments in distortion of the waveforms are accomplished by the potentiometer R5 (100K). This circuit is designed to produce waveforms with frequency range between 20Hz and 20 kHz. The function generator IC requires dual DC power supply. A dual power supply of -15/+15 as shown in the circuit is used here for powering this circuit.

Circuit Diagram

Simple Function Generator Circuit

Simple Function Generator Circuit

Notes

  • Use a good quality PCB to assemble this circuit.
  • This is the best function generator circuit for a beginner to start with and is of course a must on the work bench of an electronics hobbyist.
  • Square, triangle and sine waveforms are obtained simultaneously from pins 9, 3, 2 respectively of the function generator IC.
May 31st, 2010

Simple Battery Monitor Circuit

Circuit Description

Here is the circuit diagram of simple battery monitor circuit. The main part of this circuit are the IC MN13811G from Panasonic and an efficient flasher circuit based on transistors Q1 (BC 558) and Q2 (BC 548). This circuit works in such a way that it produces a flash of LED when the output voltage of battery comes below a preset value.

In this circuit, the preset value of voltage is fixed at 2.4 volt. The circuit is designed in such a way that the IC is enabled when the output voltage of battery drops below 2.4 V. This enables the flasher circuit based on transistors Q1 and Q2 that drives LEDs and it flashes. One of the main advantages of this circuit is the power efficiency. This circuit draws a current of 1 uA when LED is not flashing and 20 uA when LED is flashing.

Circuit Diagram

Simple Battery Monitor Circuit

Simple Battery Monitor Circuit

Notes

  • Use a good quality PCB to assemble this circuit.
  • This circuit here is an ideal one for monitoring the level of all types of 3V batteries.
  • IC MN13811 series are available with different trip point voltages (from 2.4V t0 4.8V).
  • Soldering iron must not be kept at the tip of IC’s pins for long time.
May 30th, 2010

Window Foil Burglar Alarm Circuit

Circuit Description

The circuit diagram of window foil burglar alarm has been published here. The main parts of this circuit are SCR H1 (TYN 612) and transistor Q1 (BC 107). This burglar alarm can be fitted in windows to check breaking attempts.

Here the sensing element of break attempt is a network of fine wire element fitted through the window glass. At normal condition, the transistor Q1 will be in off state since its base is connected to the ground. Then SCR will be in non-conducting state since it has not been triggered. When a break attempt of window comes, then the wire elements will break and the base of transistor will connect to positive potential. This turns on Q1 and the output of it triggers SCR.  This turn on of SCR turn horn to blow and the circuit remains on unless power supply is switched off.

Circuit Diagram

Window Foil Burglar Alarm Circuit

Window Foil Burglar Alarm Circuit

Notes

  • To setup the circuit, make switch S1 open and adjust R2 to get a 1V between base of Q1 and ground. Now transistor will be conducting and horn will be blowing.
  • Now, close S1 and reset the power supply .The transistor Q1 will be off and horn will not be blowing. Then circuit is ready.
  • Make a loop of very fine wire through the window glass to make the window foil (two or three lines running in both direction is enough).