Simple DC Voltage Doubler Circuit

A voltage doubler circuit is like a mini battery booster.

It can take the regular voltage from your batteries and give you almost double the power.

It does this with some clever components like diodes and capacitors, acting almost like tiny switches and containers for electricity.

Sometimes, it might even use transistors or little chips to help out.

Think you have a stream of electricity flowing from your batteries.

The voltage doubler acts like a special tool with two parts: one part chops the stream into chunks, and the other part smooths those chunks back out into a stronger, steadier flow almost like double the original power.

Circuit Working:

Parts List:

Essentially, the circuit consists of a square wave generator employing the 555 IC, followed by a transistor based final stage T1 and T2.

The actual voltage doubling operation involves components D1, D2, C4 and C5.

The 555 IC operates as an astable multivibrator, producing a frequency of approximately 8.5kHz, which drives the final transistor stage T1 and T2.

Here is how the voltage doubling occurs:

During the low phase of the signal, T1 blocks while T2 conducts allowing capacitor C4s negative terminal to ground and charge through D1.

Conversely, during the high phase, T1 conducts while T2 blocks preventing C4 from discharging as it is blocked by D1.

Consequently, the subsequent capacitor C5 accumulates a combined voltage from C4 and the power supply 12V input.

Under normal conditions, the circuit delivers around 20V with a maximum load not exceeding 70mA.

The actual output voltage hovers around 18V resulting in an efficiency rating of 32%.

At lower current levels the output voltage increases.

For stability in output voltage, a 3 pin voltage regulator IC can be incorporated at the output.

However, it is crucial to consider the regulator ICs own current consumption which should not exceed the total permissible current consumption of 70mA.

Formula:

To get a greater DC voltage from a lower input voltage, a DC voltage doubler circuit can be built.

The main concept is to operate a voltage doubling circuit using transistors, diodes, capacitors, and resistors by creating a square wave oscillator with the 555 IC.

The following formula is used to approximate the output voltage V_out of the voltage doubler circuit:

V_out ​= 2 × V_in​ − V_D​ − V_drop​

Where:

• V_in​ is the Input DC voltage.
• V_D​ is the voltage drop across the diodes (typically around 0.7V for each diode).
• V_drop​ is the voltage drop across the transistors and other components.

A basic knowledge of the operation of a voltage doubler circuit may be obtained from the formula given.

To really accomplish the intended voltage doubling effect effectively and consistently, careful component selection and arrangement will be needed.

How to Build:

To build the DC voltage doubler circuit you need to follow the below mentioned assembling steps:

Prepare Components:

• Gather all necessary components and ensure they match the specifications mentioned in the circuit design.

Assemble LM555 Timer Circuit:

• Follow the datasheet of 555 IC to build an astable multivibrator circuit.
• This involves connecting resistors and capacitors as per the desired frequency of 8.5kHz.

Connect Transistor Stage T1 and T2:

• Connect transistors T1 and T2 to the output of the 555 IC.
• Ensure proper biasing and connections according to their datasheets.

Integrate Diode-Capacitor Network D1, D2, C4 and C5:

• Connect diodes D1 and D2 along with capacitors C4 and C5 as described in the circuit.
• Make sure to observe the polarity of the diodes and capacitors.

Test and Troubleshoot:

• Power up the circuit and measure the output voltage across C5.
• Verify that it is approximately double the input voltage around 20V with a 12V input.

Finalize and Secure Connections:

• Once the circuit is working as expected, secure all connections properly to prevent accidental short circuits or loose connections.

Testing and Calibration:

• Test the circuit under different load conditions to ensure stability and efficiency.
• Calibrate if necessary to achieve desired performance.

Note:

By following these steps carefully and paying attention to component orientation and connections, you should be able to build the DC voltage doubler circuit successfully.

Conclusion:

To conclude, a DC voltage doubler circuit is an electronic setup that doubles the input voltage to approximately twice its value using diodes, capacitors and switching elements.

This compact and efficient circuit configuration finds applications in scenarios requiring higher DC voltages from lower voltage power sources offering a simple solution without the need for bulky transformers or complex circuitry.

References:

Voltage doubler

DC-DC Voltage Doubler