Power amplifier electronic circuits-tube audio rf amplifiers

Circuit Description

The circuit given here is a three phase auto charger circuit. Any modern electrical or electronic device can operate from 230 V ac supply with 15% tolerance in voltage. That is the device will work normally for a voltage range between 195V and 265V. The device may not work properly beyond this range of voltage. To change over to the other phase, the voltage required for can be chosen. Here in this circuit, a step down transformer with a secondary voltage of 15-0-15 volt at 500 mA is used for the operation of 18V relay. Here switching of the relay can be controlled by the resistors R3 and R1 respectively.

Circuit diagram

3-Phase Auto-Changer Circuit

Connection diagram

3-Phase Auto changer circuit-Connection Diagram

Notes

• The circuit given here is designed by Mr.Seetharaman V.S from Chennai.
• Transformer T1 can be a 15-015 V secondary, 230V primary, 500mA step down transformer.
• For chatter free operation, use a capacitor of 100μF 40 volts in parallel with relay.
• Use one mould for each phase.
• The connection diagram given above gives the relay interconnections.

Circuit Description

Here is the circuit diagram of Baxendall tune control circuit. The name Baxendall for this circuit is because this circuit is based on the tune control circuit developed by Baxendall. This circuit uses two transistors Q1 and Q2 (BC 109C) which are the central active components in this circuit. This circuit can produce a maximum cut or boost of around 12 dB at 10 KHz (treble) and 50Hz (bass).

The whole circuit consists of three stages such as input stage, Baxendall circuitry and output stage. The input stage is an emitter follower centered on transistor Q1 and consisting of resistors R1 (560K), R2 (470K) and R3 (2.2K). This input stage has unity gain and the output of this stage is fed to the Baxendall stage through the capacitor C1 (10 uF). Potentiometers R7 and R10 (47K) are used for the adjustment of bass and treble respectively. The output stage of this circuit consists of transistor Q2 and resistors R11 (2.7M), R12 (10K) and R13 (2.2K). The output of second stage is given to the output stage and the final audio output is produced from the output stage with a gain of three.

Circuit diagram

Baxendall Circuit

Notes

• Assemble the circuit on a good quality PCB.
• A 12V DC supply is used for powering this circuit.
• Both the bass and treble can be independently adjusted.
• The input stage of this circuit has an impedance of 225 kilo ohms.

Circuit Description

The circuit diagram of FM remote encoder/decoder has been published here. The main parts of this circuit are the ICs RF 600E and RF 600D. This circuit consists of two main parts such as transmitter (encoder) section and receiver (decoder) section. Among these, the transmitter stage uses IC1 (RF 600E) as its core part and the receiver stage uses IC2 (RF 600D) as its core part. These devices are designed to provide a high level of security and it can operate from DC supply between 2 to 6.6V DC.

In the encoder section, pins 1 to 4 forms the switch inputs of IC1. When each push button switch is pressed a corresponding code will be generated at the pin 6 which is the output pin. Transistor Q1 is used for buffering the encoded signals.  After buffering, this signal is given to the FM transmitter module. In the decoder section based on IC2 has four digital data output pins (pins 17, 18, 1 and 2) corresponding to the switches S1 to S4 of the transmitter section. The receiver module receives the transmitted code and feds it to the data input (pin 9). After the signal processing in IC2 the transmitted signal will be obtained.

Circuit diagram

FM REMOTE ENCODER CIRCUIT

FM Remote Encoder Circuit

FM REMOTE DECODER CIRCUIT

FM Remote Decoder Circuit

Notes

• Assemble the circuit on a good quality PCB.
• The ICs can be operated from anything between 2V to 6.6V. It is better to use batteries for powering this circuit.
• Use miniature push button switches for S1 to S5.
• Various electronic circuits like remote control systems, remote alarm systems, anti theft alarms etc can be implemented using the RF600E/RF600D pair.