Power amplifier electronic circuits-tube audio rf amplifiers

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

May 30th, 2010

Simple Tweeter Crossover Circuit

Circuit Description

The circuit diagram of tweeter crossover circuit has been described here. The advantage of this circuit over circuits of single coil speaker is that it can handle both high and low frequency signals simultaneously. A tweeter circuit can produce a better sound clarity than single speaker circuit if low frequency is filtered out from the amplifier output.  That principle is applied in this particular circuit. Here a low pass filter circuit consisting of elements C1, C2 (25 uF) and potentiometer R1 (100 ohm) is used for filtering high frequencies. This filtered output is given to the tweeter (K2). The existing woofer (K1) is driven with the low frequency.

Circuit Diagram

Simple Tweeter Crossover Circuit

Simple Tweeter Crossover Circuit

Notes

  • The power rating of potentiometer should not be less than 2 Watts.
  • Use electrolytic capacitors for C1 and C2.
  • The tweeter can be a 2 to 3 inch, 4 to 8 Ohm one.
  • Potentiometer R1 is used to adjust the output level of tweeter to that of woofer to match both.
May 28th, 2010

Remote Controlled Appliance Switch Circuit

Circuit Description

Here is the circuit diagram of remote controlled appliance switch circuit. The main parts of this circuit are IC1 (NE 555), IC2 (CD 4017), IC3 (TSOP 1738), Q1 (BC 158) and Q2 (SL 100). This device can switch on/off any appliance connected to it using a TV remote.

Here the IR remote sensor is TSOP 1738 whose output is high when no signal is falling on it and becomes high if 38 KHz signal from TV remote falls on it. When the output of IR sensor becomes low, that will turn transistor Q1 into conducting state. Its low output triggers IC1 which is wired as monostable multivibrator and it produces 4 sec long high signals at its out put. This signal is given as clock to IC2 which is a flip-flop having two output pins (2 and 3). Then pin3 goes low and pin2 goes high. The output of pin2 is used to drive the relay through transistor Q2. The output of IC2 toggles when the next signal comes. As a result of this on each press of remote, the relay will be toggled and hence the appliances connected to it can be switched on/off by remote.

Circuit Diagram

Remote Control Appliance Switch Circuit

Remote Control Appliance Switch Circuit

Notes

  • Use a good quality PCB or common board to assemble this circuit.
  • Use TV remote having a frequency of 38 KHz.
  • The appliance can be connected through NO or NC and C contacts of the relay.
  • Use a 6 V DC regulated supply for powering this circuit.

May 28th, 2010

Simple Door Bell Circuit

Circuit Description

The circuit diagram of door bell circuit using UM 66 IC has been published here. This is the simplest door bell circuit in which the central part is the IC UM 66 as the name says. The difference of this circuit with the melody generator circuit is that the melody generator plays music till you release the switch after pressing whereas in this circuit, after one press full song will be played. In this circuit if once switch is pressed, the capacitor C1 (220 uF) gets charged and the transistor Q2 (BC 548) keeps the IC for playing music till its end. The charging time of the capacitor C1 determines the music playing time of IC UM 66. This can be adjusted by the potentiometer R1 (100K). The speaker K1 is driven by the transistor Q1 (BC 548).

Circuit Diagram

Simple Door-Bell Circuit

Simple Door-Bell Circuit

Notes

  • The voltage given to UM 66 IC should not be larger than 4.5 V.
  • Adjust pot R1 to select the playing time for music, whether full tone or a part in one press.
  • POT R2 is optional but if included, the loudness can be adjusted.