• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

New Projects | Privacy Policy | About us | Contact | Disclaimer | Copyright | Videos 

You are here: Home / Battery Chargers / 12 V to 19 V Converter Circuit

12 V to 19 V Converter Circuit

Last Updated on December 15, 2021 by Swagatam 7 Comments

The following post explains how to build a simple 12 V to 19 V boost converter circuit which can used to charge a 19 V battery from a 12 V car battery.

The main application of this circuit could be for the charging of a laptop battery from a car battery,

caution electricity can be dangerous

How the Circuit Works

The 12 V to 19 V converter circuit diagram can be seen in the following figure.

The working principle is actually very straightforward.

A free-running astable oscillator is employed to operate a voltage doubler circuit.

A series pass transistor is used to regulate the output voltage, which is controlled by a comparator. The earth connections for the input and output lines is the same and is common with the negative of the 12 V supply source.

IC1B becomes the main active part of the the astable multivibrator configuration. Capacitor C1 and resistor R4 which are connected across the feedback path provide a working frequency of 15 kHz roughly.

Diode D1 and resistor R7 make sure that the square wave output operates with a 50:50 duty cycle.

C1 capacitor must be a good quality capacitor with high stability and low temperature coefficient features, a ceramic type capacitor should do the job well.

The dode D1 should be rated with a temperature characteristics so that the output square wave is maintained correctly all the time regardless of the output load conditions and circuit heating.

Transistors T2 and T3 gets switched alternately through the square waves generated by the IC1B.

When T3 is in the switched ON period, capacitor C3 charges up to 12 V by means of D2. Next, while the T3 goes into the switched OFF period, causes T2 to turn ON, which enables the negative terminal of C3 to be instantly linked with the +12 V supply.

However, in this situation the charge stored inside in C3 is unable to change immediately, therefore as soon as the C3 negative terminal gets linked with the high 12 V potential, it becomes necessary for its positive terminal to also step up.

The situation causes the C3 positive terminal to get ‘boosted up’ to approximately two times the supply voltage.

In real life operation , due to the losses occurring through the diodes and transistors essentially mean that the output cannot be exactly two times the supply input level, rather will be a slightly below the expected 2X level.

Schottky diodes are employed in the circuit to ensure that the forward voltage drop is kept to the minimum. D3 is used for rectifying the voltage and C4 is configured to store the rectified output from the diode.

Make sure to use very high quality capacitor for C3 since it will be solely responsible for delivering the entire output current to the load. The regulation for the output voltage is executed by op-amp IC1A.

The potential divider created by the resistors R14 and R12 detects the T4 collector voltage and then IC1A compares it with the reference voltage generated from the network comprising of the parts R6, R9 and zener diode D4.

The level of the stepped up 19 V output can be fixed by adjusting the value of R14. A 15 kΩ value for R14 will provide an approximate output voltage of 19 V.

The ripple voltage content of the 19 V output at full load will be as shown in the next figure.

If the capacitor value C6 is increased, will ensure that the reference voltage goes up at a very slow rate when power is first switched ON. This feature can provide this 12 V to 19 v converter circuit a nice soft-start or slow-start characteristic. This switch-on delay can be verified by looking at the LED D6.

PCB Design

The complete PCB design and the components overlay diagrsm is shown in the following image:

You'll also like:

  • 1.  Ni-Cd Low Battery Monitor Circuit using Lambda Diode
  • 2.  Battery Charger for Positive Earth Cars
  • 3.  NiMH Battery Charger Circuit
  • 4.  Multiple Battery Charger Circuit using Dump Capacitor
  • 5.  Make this Fast Battery Charger Circuit
  • 6.  Triac Battery Charger Circuit

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

Have Questions? Please Comment below to Solve your Queries! Comments must be Related to the above Topic!!

Subscribe
Notify of
7 Comments
Newest
Oldest
Inline Feedbacks
View all comments

Primary Sidebar

Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (52)
  • 4060 IC Circuits (26)
  • 555 IC Circuits (99)
  • 741 IC Circuits (20)
  • Arduino Engineering Projects (83)
  • Audio and Amplifier Projects (115)
  • Battery Chargers (83)
  • Car and Motorcycle (94)
  • Datasheets (73)
  • Decorative Lighting (Diwali, Christmas) (33)
  • Electronic Components (101)
  • Electronic Devices and Circuit Theory (36)
  • Electronics Tutorial (120)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Fun Projects (13)
  • GSM Projects (9)
  • Health Related (20)
  • Heater Controllers (29)
  • Home Electrical Circuits (103)
  • How to Articles (20)
  • Incubator Related (6)
  • Industrial Electronics (28)
  • Infrared (IR) (40)
  • Inverter Circuits (98)
  • Laser Projects (12)
  • LED and Light Effect (93)
  • LM317/LM338 (21)
  • LM3915 IC (25)
  • Meters and Testers (66)
  • Mini Projects (149)
  • Motor Controller (67)
  • MPPT (7)
  • Oscillator Circuits (26)
  • PIR (Passive Infrared) (8)
  • Power Electronics (34)
  • Power Supply Circuits (79)
  • Radio Circuits (10)
  • Remote Control (48)
  • Security and Alarm (62)
  • Sensors and Detectors (121)
  • SG3525 IC (5)
  • Simple Circuits (75)
  • SMPS (29)
  • Solar Controllers (61)
  • Timer and Delay Relay (53)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (41)
  • Ultrasonic Projects (16)
  • Water Level Controller (45)

Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator

© 2023 · Swagatam Innovations

wpDiscuz