Power amplifier electronic circuits-tube audio rf amplifiers

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

May 3rd, 2010

Simple Electronic Combination Lock Circuit

Circuit Description

This section describes the circuit diagram of simple electronic combination lock. The central part of this circuit is the IC LS 7220. This circuit is used for the activation of a relay which controls a device on/off states while pressing a combination of 4 digits from keyboard. To set the combination, connect the appropriate switches to pin 3, 4, 5 and 6 of the IC through the header. Then connect the rest of the switches to pin 2 of IC. This is for correcting an invalid key press. The output relay will be activated if and only if the correct key combination is pressed for a preset time. In this circuit, the value of preset time is determined by the capacitor C1. Preset time can be increased by increasing the value of capacitor C1.

Circuit Diagram

Electronic Combination Lock Circuit

Electronic Combination Lock Circuit

Pin Diagram of LS 7220

LS 7220 Pin Diagram

LS 7220 Pin Diagram

Parts List

  • Capacitors: C1 (1uF 25V), C2 (220uF)
  • Resistors: R1 (2.2K)
  • Transistors: Q1 (2N3904 NPN Transistor)
  • Diodes: D1 (1N4148 Rectifier Diode)
  • Other Components: K1 (12V SPDT Relay)
  • U1  (LS7220 Digital Lock IC)
  • S1-S12 (SPST Momentary Pushbutton)
  • HD1 (12 Position Header)

Notes

  • Use a good quality PCB to assemble this circuit.
  • For the key pad, arrange switches in a 3X4 matrix on a PCB.
  • The circuit can be operated from 5V to 12V.
  • In this circuit, preset time for key press is set as 6s.
May 3rd, 2010

Mini Amplifier Circuit

Circuit Description

The circuit diagram of Mini 2 W amplifier has been published here. The core part of this circuit is the IC TDA 7052 from Philips Semiconductors. The IC TDA7052 is a mono output amplifier. This IC has some features like no external components needed,  no switch-on or switch-off click sounds , great overall stability ,very low power consumption(quiescent current 4mA) , low THD, no  heat sinks required and short-circuit proof. This amplifier IC has an internally fixed gain of 40 dB. Bridge-Tied-Load principle (BTL) is used by TDA7052 to compensate the reduction of output power due to low voltage supply.

The IC TDA7052 is an 8-lead DIP and is mainly designed for battery-operated portable audio circuits. Volume control in this circuit is done by potentiometer R1 (4.7 K). Capacitors C1 and C2 are used for supply voltage elimination when supply source is battery eliminator.

Circuit Diagram

Mini Amplifier Circuit

Mini Amplifier Circuit

Notes

  • Use a good quality PCB or common board to assemble this circuit
  • For operations using a battery C1 and C2 are not necessary
  • IC TDA 7052 can provide  an output  of around 1 to 2 W  into an 8 Ohm load with a power supply of 6 V
  • This amplifier can operate even from a 3V Mercury button cell and this makes it ideal for battery operated gadgets.
May 3rd, 2010

Simple Amplifier Using LA 4440 IC

Circuit Description

Circuit diagram of 19 Watt amplifier using LA 4440 has been published here. This amplifier circuit is based on the IC LA 4440 developed by Sanyo. In this circuit, amplifier IC LA 4440 acts as bridge amplifier. This IC has an extra feature that is protection against thermal, over voltage and short circuits. Adequate heat sinks should be provided for this IC in PCB.

12 V DC power supply is used for powering this circuit. The power supply used should be able to deliver a current of 3A at least. This IC can with stand up to 25 V but it is safe to use up to 16V. A 4 ohm speaker is used here as load. This speaker load can be 8 ohm but in that case output power will become half of that with 4 ohm speaker.

Circuit Diagram

Amplifier using LA 4440 ic

Amplifier using LA 4440 ic

LA 4440 Specifications

la 4440 specifications

la 4440 specifications

Notes

  • Use a good quality PCB to assemble components for this circuit. Carefully understand the specifications of LA 4440 given above.
  • This amplifier can deliver a 19 W Rms on a 4 Ohm speaker.
  • The IC LA 4440 also incorporates an audio muting function but it is not required in this circuit.
|