Showing posts with label dc. Show all posts

Friday, December 12, 2014

Simple DC DC Converter

This schematic shows you how to build a dc-dc schematic.Here's a DC to DC circuit put together just from parts found on the test-bench. All it took was two transistors, two resistors, an audio transformer, a bridge and two caps. It may not be the ultimate in performance, but it does work.

The key to how it works is the transformer. As you can see, two transistors drive the transformer primary with the base drive for each coming from the collector of the other.When power is applied, suppose Q1 turns on a few nanoseconds faster than Q2.

Wednesday, October 29, 2014

Low voltage DC motor speed control circuit using TDA7274

Description.
Here is the circuit diagram of a low voltage /low power DC motor speed controller based on the IC TDA 7274 from ST Microelectronics. The IC TDA 7274 is a monolithic integrated DC motor speed controller intended for low voltage/ low power applications. Built in internal voltage reference voltage, wide input voltage range (1.8 t0 6V), high linearity, 700mA output current, excellent temperature stability etc make this IC well suitable for almost all low power DC motor speed control applications.
The motor to be controlled is connected between pin3 (Vs) and pin4 (output) of the IC. Resistor network comprising of R1, R2, and R3 is the section that deals with the speed control. Control pin (pin8) of the IC is connected to the junction of R2 and R3 and the speed of the motor varies linearly according to the position of POT R3. Capacitor C1 rectifies the fluctuations in motor speed and capacitor C2 cancels the motor spikes.

Notes.
The circuit can be assembled on a Perf board.
Power supply Vs can be anything between 1.8V to 6V and it must be selected according to the rating s of the motor.
Maximum output current capacity of this circuit is 700mA.
TDA7274 must be mounted on a holder.
POT R3 can be used to vary the motor speed

Friday, September 26, 2014

DC Voltage Doubler Circuit Explained

The inverters, N3. . . N6, are connected in parallel and operate as a buffer stage to reduce the load- dependence of the circuit.
Depending on the clock signal of the oscillator, point A in figure 1a is connected to the earth rail for a particular time per period and to the supply voltage for a particular time.
This causes the voltage across capacitor C2 to rise to almost twice the supply voltage. If D1 is connected to earth and the -polarities of diodes D1, D2 and capacitors C1, C2 (figure 1b) are reversed, the output at A will be a negative voltage and, in the no load condition, it will be at the same level as the supply voltage.
In both cases, unfortunately, the output voltage is dependent upon the load. As the load increases, the output voltage drops; in contrast, the superimposed a.c. level rises. The table shows the values measured in the circuit for load currents of 5 mA and 15mA.
This simple circuit can produce a d.c. voltage which is approximately twice the supply voltage, in the no- load condition.
Whilst point A is connected to earth, capacitors C1 and C2 charge up to the supply voltage via diodes D1 and D2. The oscillator then switches point A to the supply voltage potential during the remaining period, capacitor C1 transfers a part of its charge to capacitor C2.
The 4049 IC contains a total of six inverters. Two of them, N1 and N2, form an oscillator together with R1 and C3, of which the frequency is about 10 kHz.

Saturday, September 6, 2014

Digital DC Power supply using PWM with PIC microcontroller

In our lab I saw many DC power supply which have a variable knob to regulate the output. I was dreaming to make such a project where I can regulate the voltage using push button.As I am not an industrial level expert so this project is just about a digital DC power supply of small range(5V-12V). You can press push buttons to increase or decrease output voltage.Here we use LM317 to regulate the output voltage. Output voltage is controlled by the PWM output of a pic microcontroller.An OP-AMP is required to amplify the PWM output level. The idea is simple and easy to implement in schema.

Necessary Software:

1. Proteus 7.8 Professional
2. MicroC Pro
3. PICKIT 2.61 Boot Loader

Necessary Equipment:

1. PIC 16F73
2. LCD 16x2
3. 20 MHz Oscillator
4. Variable resistor (5k Ώ, 1k Ώ, 50k Ώ)
5. 7805 Voltage Regulator
6. 7818 Voltage Regulator
7. LM317T Voltage Regulator
8. LM741 Op Amp
9. Push Button Switch
10. Resistor (1k Ώ, 220Ώ)
11. Capacitor (47, 10, 1, 0.1 uF)
12. Vero board
13. Heat Sink

Methodology:

Figure1: Block Diagram of whole system

Schematic Diagram:

Figure 2: Schematic Diagram of the schema

Description:

· LM317 can give output of 3-37V . It can change its output voltage according to the adjust pin voltage.
· PWM signal is generated from microcontroller. The signal is applied to RC low pass filter which makes a DC voltage level.
· This voltage is applied to Op Amp to get required gain.
· This amplified voltage is applied to LM317 adjust pin.
· From microcontroller we adjust the width of PWM signal. More width gives higher DC level.
· It also changes the adjust pin voltage which controls the output of LM317.

Final Output:

Possible Application:

· Smooth speed control of DC motor

· Valve control of liquid and gas flow.
· Supply for different Electronic Circuit etc.

Downloads:

Download the full project file here.

Friday, September 5, 2014

4 W audio power amplifier with DC volume control

GENERAL DESCRIPTION:

The TDA1013B is an integrated audio amplifier circuit with DC volume control, encapsulated in a 9-lead single in-line (SIL) plastic package. The wide supply voltage range makes this circuit ideal for applications in mains and battery-fed apparatus such as television receivers and record players. The DC volume control stage has a logarithmic control characteristic with a range of more than 80 dB; control is by means of a DC voltage variable between 2 and 6.5 V. The audio amplifier has a well defined open loop gain and a fixed integrated closed loop. This device requires only a few external components and offers stability and performance. 4 W audio power amplifier with DC volume control

Features:

Few external components

Wide supply voltage range

Wide control range

Pin compatible with TDA1013A

Fixed gain

High signal-to-noise ratio

Thermal protection

PINNING:

power ground

amplifier output

supply voltage

electronic filter

amplifier input

control unit output

control voltage

control unit input

signal ground (substrate)

Circuit Diagram

4 W audio power amplifier with DC volume control

Datasheet for TDA1013B: Download

Friday, August 29, 2014

How to Make 12 9 Volt DC to DC Converter BD139

This schema is a DC voltage output from a small DC input generate large voltage.It ‘s easy and quick to do, and reducing the value of the Z-diode, the schema can be universally adapted to other output devices of the schema voltages. The give and all diagrams represent a DC converter with 12V battery 9 volt DC input and output.

12-9 Volt DC to DC Converter Circuit Diagram

With the 10V zener diode, as in the diagram, the output voltage is approximately 9.3 volts DC. The supply voltage is used, should always be at least a few volts higher than the Zener voltage. In this example, I have a 12 Volt DC battery to provide regulated 9-volt DC output. Link

Wednesday, August 20, 2014

Basic DC to DC Converter Electronic Schematic Wiring diagram

Those of you who frequently use devices that work on battery or you need a negative trend at the moment you have a single positive, will definitely look for a converter like the one described below. Constructing it, you can convert a positive voltage of a battery of 9 V to negative using well known integrated 555. The same schema can also be used in cases those requiring two symmetrical lines of power, when available a single battery.

The integrated TLC555 is the old bipolar NE555, manufactured with technology but CMOS. Unless you have this type of integrated, you might as well use an 7555. In this construction, the TLC555 is syndesmologimeno arranged in a ground unstable.The oscillation frequency determined by the A2, A3, C 1 and approaching 20 kHz.

DC to DC Converter Electronic Schematic Diagram

The rectangular waveform produced by the oscillator is therefore time to time (Duty Cycle) close to 50%. The waveform is led to a rectifier Doubler formed by C3, O1, O2 and C4. In place of O1 and O2 should be placed diodes Schottky type VAT85 due to low voltage correct direction which is equal to 0,4 V (silicon diodes such as type 1 N4148, show a tendency equal to 0,7 V). The capacitor C4 cares for smoothing the voltage bristled, while the C5 relieve the signal from noise high frequencies. With the help of A1, C6 and C7 achieved the disconnection of supply voltage timer.

The consumption of the inverter to power depends largely on the load to be connected to the output of -9 V. As seen from the values ??indicated in the table, the output voltage is held within tolerable levels, as the load current is kept less than 1O mA. To make it easy to integrate the inverter into any electronic device, I suggest you build a small PCB board.

AC DC POWER SUPPLY MINIATURE ISOLATED

AC/DC POWER SUPPLY MINIATURE ISOLATED

AC/DC POWER SUPPLY MINIATURE ISOLATED CIRCUIT uses a novel approach to produce a fully isolated and regulated 5 volts @30ma from the 120vac power line. It uses two tiny SCRs that alternately discharge two capacitors through a miniature high frequency transformer. The voltage spikes produced through the transformer are rectified, filtered and regulated. A very common 8 ohm audio impedance matching transformer can be used for the transformer.