12V to 15V-24V Boost Converter Circuit

This boost converter circuit can convert a 12V 10A input into a maximum 24V 5A output. The output voltage can conveniently be selected from many ranges: 18V, 20V, 22V, and 24V. The circuit is also relatively easy to make and assemble. The full specification is listed below.

Feature of This Circuit

• Input Voltage : 12V 10A 
• Minimum Output Voltage : 13.6V
• Maximum Output Voltage : 26.3V
• Selector Voltage : 18V, 20V, 22V, 24V
• Maximum Output Current : 4A-5A

When using a laptop in an area without electricity, we would normally have to rely on the integrated battery, which at best would last a couple of hours. So, if we want to use it for an extended period of time, we will need to connect it to a power source.

In this case, we would use a solar cell and battery system. However, that system alone can only supply a voltage of 12V, and according to the laptop’s charger, it requires a voltage of 19V 3.8A to charge. Therefore, we need to find a way to increase the battery voltage.

The best way to increase battery voltage is to use a boost converter, which we would often choose the MC34063 because it is easy-to-use and inexpensive. However, the MC34063 by itself can only supply a maximum current of 0.5A.

Thus, to amplify the current, normally we would use a power transistor, but this time we will use the MOSFET instead, because it works well with high frequency, can drive high current, and is relatively easy to use.

The Circuit Structure

I got this boost converter circuit from a local electronic store. It can convert a 12V input to 18V, 20V, 22V, or 24V outputs, which is in line with the initial requirements we set earlier.

But I still think it would be interesting to learn how the circuit works, so let’s start with the block diagram.

The Protection & Softstart

A circuit that has high current should also have an adequate level of protection, especially against shortcircuits, which can cause significant damage to the IC and other semiconductors.

(1) When supplied with the correct polarity of current, the positive current enters the circuit through the D2 as a base bias current for the Q3, causing the Q3 to turn on and function similarly to a closed switch. (2) As a result, current flows through the relay’s coil, causing contacts C and NO to close. (3) Allowing the remainder of the current to flow to the boost coverter circuit. Meanwhile, the LED1 lit up, indicating that the circuit was working.

The circuit would not let current through if the following conditions were met:

• Vin is less than 9V; the voltage is too low, causing the relay coil to not be able to pull in the contacts.
• Vin is reversed polarity; the negative voltage cannot pass through D2 or it received reverse bias.

Basic MC34063 Switching Regulator

Now we moved on to the basic MC34063 switching regulator part. It consists of a few important components, such as C1, C4, D1, L1, and the MC34063 itself.

C3 helps keep the current smooth during a spike in load current; without it, the load might get damaged. C2 and R3 filter the current for the IC1, thus improving the overall efficiency of the circuit.

The External Current Booster

Currently, the circuit can only supply a maximum current of 500mA. So, we will have to use an external current booster; it will amplify the current to around 4A, which is what we need.

In the above circuit, Q1 and Q2 work together as a push-pull preamplifier, which increases the effciency of amplifying the AC signal. The preamplifier is then connected directly to G of the MOSFET, thus allowing better amplifaction of high-frequency signals. Also, the MOSFET biases with voltage, meaning that it can drive current through L1 and D1 at its maximum potential.

The L1 is 0.03mH or 30uH, capable of withstanding a current of 5A. The D1 is BA550A, which can withstand 5A current and 150V.

While the Q4 is IRF3205, it has the highest drain-source (VDS) of 55V and continuous drain current of 110A. This MOSFET is often found in an inverter, and it is also inexpensive. Lastly, R2 and R4 are there to increase the stability of the circuit.

Voltage Selector

Next is the resistor voltage selector circuit; it is used to set the output voltage of the circuit. It can select between 18V, 20V, 22V, and 24V by using J1 through J4. You can also use the VR1 to fine-tune it further.

For instance, if we jump the J1, the output voltage will be about 18V, and we can use the VR1 to adjust it to any voltage within the 18V range. The lowest output voltage is 13.8V, while the highest is 26V, which means that we can set it to match the laptop power supply of 19V.

Complete Circuit

Now we combine every part together into a complete High Current 12V to 15V-24V Boost Converter Circuit.

Testing the Circuit

We test this circuit by using it to power an old laptop with a 12V/7A battery as a power source. We selected the J1 (18V) jumper and adjusted the VR1 until getting the 19V that the laptop needs. Then plug it in to the laptop; it works quite well, though the output voltage did decrease by a little bit to 18.91V.

We want to know the signal wave between the D and S of the MOSFET, as it can indicate if the switching circuit is working correctly. When the load requires a lot of current, the frequency will increase as well as the signal level (Vp-p); the result we got is a frequency of 30kHz to 100kHz, as shown below.

When the circuit is operational, there are two notable heat-generating components, which are Q4 and L1. In addition, measuring the L1 inductor yields a value of 33uH and a resistance of 0.2ohm.

Also, if you have a TDA2004 and want to try the circuit below, it is interesting, but the efficiency is lower than using a Switching mode regulator circuit because it operates at a lower frequency.

Buy a 12V to 24V step-up converter at Amazon HERE

Simple 12V to 24V Double Voltage Converter Circuit

Do not be surprised. If see TDA2004 is in the circuit. Even it is good at the mini amplifier.

It is really, really. We are building a type of switching regulator with it.

We use it to produce the high current pulse to the simple double voltage circuit. Which they work with the capacitors and diodes.

This does not need to use any coil. So, easy and cheap. And, Imagine when you finish this DC converter job. You are bored. You can rebuild it into a nice amplifier.

This project can increase the DC voltage from 6V to 12V, or from 12V to 24V. It is a simple DC to DC step-up converter circuit.

The working principle

First of all, the voltage comes to the circuit. Then, this voltage will charge to C5 through D1. At the pin 10(output) of IC1/1 has the voltage rises up. Until almost equal to the voltage of the power supply.

Circuit diagram of step-up DC converter using TDA2004

Next, D2 passes the current to charge into C6. It makes the voltage at pin 10 of IC1/1 about 0V. However, the voltage across C6 or the output is equal to the power supply.

After that, the output(pin 8) of IC1/2 starts to have the voltage rise instead. Because C5 stops charging, so, C7 is charged instead, through the power supply.

Thus, there is the current pass D3 to charge into C6. And, pin 8 has a voltage of about 0V.

Then, the operating of the circuit will restart same the first again.

And, both current get out of pin 8 and pin 10 will be combined at C6.

This makes the output voltage to rise up to 2 times of input. Because the voltage of pin 8 and pin 10 are the input mixes together.

The capacitors C1 through C4 act as a square wave generator about 5 kHz. To determine the working of IC1.

Building, Testing, and Application

When we get fully equipped, and build PCB as Figure below. And then, soldering equipment as Figure.

PCB of 12V to 24V step up converter circuit using TDA2004

component-layout of the 12V to 24V step up converter circuit using TDA2004

After examining the faulty circuit. Then test them with 12V battery at the input and measure voltage output will have about 22V. Please watch a video below.

If you have a 6V input. It can increase the output voltage is 12V. Or, enter the input is 12V, the output is about 24V.

Conclusion

In conclusion, this above circuit works quite well; it is suitable for increasing a voltage of around 11-13V to 24V, or at not more than 26V, while powering a load of less than 5A. It is also a great example of an easy MOSFET circuit that can handle a high-frequency signal. In the future, we may be able to, for example, further increase the voltage by utilizing multiple MOSFETs connected together in parallel. We hope that this circuit will be of use to you. Thank you for reading.

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Apichet Garaipoom

I love electronics. I have been learning about them through creating simple electronic circuits or small projects. And now I am also having my children do the same. Nevertheless, I hope you found the experiences we shared on this site useful and fulfilling.