This article explains how to construct a little helper circuit that can convert a 6V battery into a 12V power supply.
For devices that require 12V to function such as some motors or toys this circuit can help.
Objects that want a little more energy can make use of this particular circuit since it can supply more power current than some other converters.
Circuit Working:
Parts List:
| Component | Quantity |
|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | |
| 390k | 1 |
| 2.2M | 1 |
| 180Ω | 1 |
| 68Ω | 1 |
| 680Ω | 1 |
| Capacitors | |
| Ceramic 0.1µF | 3 |
| Electrolytic 100µF 16V | 2 |
| Electrolytic 200µF 16V | 2 |
| Electrolytic 1000µF 16V | 2 |
| Electrolytic 1000µF 25V | 1 |
| Semiconductors | |
| IC TDA2003 | 2 |
| Transistors TIP36 | 1 |
| Transistors BD139 | 1 |
| Diodes 1N4002 | 3 |
| Zener diode 15V | 1 |
An IC made by SGS and a number of other parts are used in this voltage converter circuit which operates between 6 and 12 volts.
Although it can be replaced with a IC TDA2002, the TDA2003 is the main IC used.
Instead of changing the complete equipment design and to accept a direct 6V power source the building cost of this converter is meant to be low enough to justify its assembly.
The design avoids the need for a transformer by focusing utility and simplicity.
The first IC known as IC1 functions as a multivibrator with steady power.
The capacitor C3 which stays about 4 kHz during standby and rises to about 7 kHz under load controls its oscillation frequency.
In the meantime IC2s output signal looks similar to IC1s but it is phase inverted.
Capacitor C4 charges through diode D1 to the power supply level which is less the voltage drop across D1 while IC1s output is at zero.
The voltage from IC1 adds up to the charge stored at C4 stopping the conduction of diode D1 when its output turns positive as it changes polarity.
Diode D2 then charges capacitor C5 to a voltage double that of the power supply level.
The supply voltage can be increased by the theoretical output.
A limiter stage which consists of a 15V Zener diode and two Darlington transistors T1 and T2 are included in the circuit to stop unnecessary voltage growth at low current consumption.
The output voltage is limited to about 14.2V by this step.
Capacitor C8 has also been added to the output to filter out ripple and minimize any hum signals especially on radios and other audio equipment.
While the transistor requires a separate heatsink hence it is advised to connect the ICs to a common heatsink near the PCB when building the 6 to 12V converter.
Capacitors C4, C5 and C6 should be raised to 2200uF in order to significantly enhance the converters output current.
Formulas and Calculations:
We can use a voltage doubler circuit to convert 6V to 12V by arranging capacitors and diodes in such a way that generates twice the input voltage.
A voltage doubler circuits output voltage is roughly estimated as follows:
Vout = 2 * Vin − Vdiode
where:
- Vout is the output voltage.
- Vin is the input voltage 6V in the circuit.
- Vdiode is the forward voltage drop across each diode.
Example Calculation:
Assume:
Vin = 6V
Vdiode (typical forward voltage drop of silicon diodes) = 0.7V (for each diode)
Vout = 2 * 6V − 2* 0.7V
Vout = 12V − 1.4V
Vout = 10.6V
This is a simple calculation and component tolerances and losses can cause some variation in the actual output voltage.
However it provides an adequate estimation of the expected output voltage.
Being familiar with the voltage doubling formula and while considering the characteristics of the components one can design a 6V to 12V voltage doubler circuit successfully.
Adjust the component settings and configurations according to the requirements and needs of the application.
How to Build:
To build the 6V to 12V voltage converter circuit below mentioned are the steps:
Prepare the PCB:
- Design or obtain a PCB design for the circuit.
- Mark the solder points and component location correctly.
Component Placement:
- Install the TDA2003 or TDA2002 ICs onto a common heatsink in close proximity to the PCB.
- Fix the Darlington transistor T1 and T2 to a separate heatsink.
- Place capacitors C3, C4, C5, C6 and C8 onto the PCB at their designated positions.
- Install diodes D1 and D2 as per the circuit diagram.
- Position the Zener diode 15V properly on the PCB.
Soldering:
- Following the circuit schematic solder each component onto the PCB.
- Avoid solder bridges and be sure all connections are correct.
Testing and Modification:
- Check all solder joints for any mistakes or shorts circuits before connecting to the main power.
- Connect a 6V power source to the circuits input terminals.
- Measure the output voltage across the proper terminals with a multimeter.
- Check that it is around 12V.
- If required troubleshoot any problems or modify component values.
- After adding the limiter stage ensure the output voltage stays within the specified range of 14.2V.
Completion:
- Complete the connections when testing is complete and the circuit performs as desired.
- In the equipment configuration where it will be used tightly mount the PCB.
- Check that the right safety precautions and insulation are in place.
Take note:
- The 6V to 12V voltage converter circuit should be successfully constructed if the above steps are properly followed.
- For more help refer to the circuit schematic and component datasheets if any issues occur during the whole process.
Conclusion:
Automotive applications, portable electronics, industrial equipment power supply and other applications which require a stable and efficient voltage conversion with high current features often use these circuits.
References:
Is it possible to convert 6V 4A (24W) DC to 12V 3A (36W) DC using step up booster?