Those who want to take the radio transmitters from a car to use in the house. You should use 12V Ham Radio power supply. Better that way, High current 13.8V power supply with enough power out of 5A to 30A. According to the size of the transmitter. I highly recommend this high-current power supply circuit. Because of Good performance, size of output 13V-14V depending on the load.
And, You can choose to build multiple sizes of 5A, 10A, 15A, 20A, 25A, 30A. According to real usage. So, help to save and easier to build.
Of course, you can buy this power supply that simple and effective with a variety of sizes. But if you build them with your own or your friends. It will be a great time while creating this project. And when completed, runs in its function. It will very proud.
Besides, this power supply circuit is also useful as a wide variety. Such as A large DC motor, car audio system, and others. Which you may apply by changing the voltage and current as needed. This circuit is very flexible.
The circuit diagram
Note: If you are beginner this circuit may is not suitable for you. You may use circuits below.
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Idea of circuit
We want the circuit that uses normal parts. So easy to buy on locals stores near us, and cheaper.
Sometimes you may have these components in your house.
A linear power supply circuit is a better choice. Because it is so easy circuit. There are a few parts in the circuit.
But It is a big size with large components.
For example, transformer if you want 30A output current. So you need the least of 30A transformer. It is so big.
By the way.
Its size is not a problem for you. Suppose that you get a big transformer from grandfather.
Yes, you can try it.
I love the linear circuit.
It must have quality
Checklists—we need these.
- The good protection circuit. When the output short circuit or overload.
- You can also choose to build a circuit size with output currents as you need. You can increase the current in a step by step, each step of 5A. Start with a minimum currents rate of 5A. And next step 10A, 15A, 20A, 25A and a maximum to 30A.
Constant voltage regulator
This circuit uses a regulator IC, LM340T-15. It keeps the level of constant voltage of 15V. Inside this IC has short circuit protection and prevent overheating.
As a result, this circuit can keep the level output voltage as well. And, If there are overload or short circuit. It will do not damage too.
How is current higher
At output pin of IC1 will be connected the Darlington emitter follower with the transistor-Q1. Then, Q1 drives six transistors Q2-Q7 in parallel.
Note: Q1-Q7 is 2N3055 NPN power transistor. Also, you may use TIP35 High-Power Transistors in TO-247. But it is more expensive than a 2N3055.
To increase the current up. From the original current maximum of 1A. When to connect these transistors Q1-Q7 to complete 7 pcs. It Makes can supply up to 30A. By parallel with the transistor Q2, from the Q3 onwards there. Each transistor can be expanded current of 5A.
The resistor 0.15Ω at emitter pin of each transistor has two act as are:
1. Check the current flowing through the transistor. Because there is the voltage drop across them as a ratio of the current flowing through each transistor.
2. The current through the transistor to equally.
Read more: Current limiting resistor
LM340-15 has a wonderful protection system.
1. Short circuit or over current power supply is not broken. IC1 can prevent overload very well. Even being long-short circuit throughout the day. It is still in good condition.
2. Hot does not work. When the temperature its highly unusual. The high-temperature protection system will order it to temporarily stops responding. Until the temperature drops. It is started as usual.
With the advantages of this IC. It should be installed on a heat sink near the transistor.
When IC1 has been heating up over defined transistor. It stops! Of course, there is no current to the transistor. So, It gradually reduces heat down. IC1 will return to run again.
Keep Reading: Electronic Circuit symbols
SCR Overcurrent protection
In the short-circuit conditions. Or Overload, Or Using too many currents. The Q2 is pulled by the current of 5A. Until the voltage of 0.75V drop across R5 – 0.15 ohms. (emitter pin of Q2). Then, this voltage to gate lead of SCR1. Next, it is enough to trigger SCR1 works immediately.
IC1 is temporarily stopped responding. Because it is overloaded. By earlier, the current of 1A flow through the IC1 and the SCR1 into loaded directly. Not through all transistors.
The SCR1 is working to hold. Until the power supply is cut off. Which automatically resets itself in this manner is called an Electronic circuit breaker.
How much output voltage
The output voltage of the power circuit is equal to the voltage output of IC1 (15V) minus the voltage drop across the base (B)- emitter (E) of transistor driver (Q1) and the transistor through (Q2) and the voltage drop across R5 emitter of Q2.
Vout = vIC – vbeQ1 – vbeQ2
= 15V – 0.6V – 0.6V
However, since the voltage drop across R5 may be changed by the current flowing through it.
So, making the voltage output of this circuit is slightly changed the switch from 14V (under no load) It may be of 13V in fully loaded conditions (regulation).
At this level, it will be maintained voltage is better than on the electric of a car. Its output voltage can be changed from 11V to 16V.
And the transmitter is normally used in the car with 12V battery is designed to be compatible with existing 13-14V voltage.
How it builds
Because the components used in this circuit there is not much. And most of them are large. Which must be installed on a heat sink.
The operation of this project, so no need to use a PCB. May use point connect the power cord, tighten the nut onto the heat sink. Then, Connect the wires to the other parts onto the heat sink.
Choose parts as you want
This circuit is flexible. You can choose a variety of devices as you want, follow these steps.
1. The C1 and F1 using this table.
Suppose You want to build 15A output current. With the output voltage of 13.8V.
You should choose C1-22,000 uF 25V. But it may do not for sale. We have to use five of 4,700uF 25V capacitors to in parallel together. So, we have a total capacity of 4,700 μF x 5 is 23,500μF. It is enough to use.
Use the size of 5A fuse is a slow, or Slow blow fuse.
2. Choose a bridge diode rectifier And the transformer T1 according to usage.
Because LM340T-15 requires a low input voltage to 17V. So, the input DC voltage to unregulated to output drop across C1 should be between 18V to 20V.
If less than 17V may not be enough to use the circuit. And, If more than 20V over 20%.
It may have more energy a loss in transistors and ICs. Making must use a larger heat sink. It is too consumes more energy than necessary.
You may choose the size of the transformer 15A. My friends go to the core steel EI at an antique store, then go hire made a new transformer. This is durable and inexpensive.
Lie detector circuit
Relationship voltage current resistance and Ohms Law
The power transistor—You can use 2N3055 which easier to buy. Or use TIP3055 is the same as 2N3055. But easy to hold on the heat sink with TO-3P. The Best, TIP35 is more high-power current more than 25A of collector current.
You can select any number SCR1 is 200V 5A such as 2N4441, C122, C106, etc.
You can add LED display to show power on by this how.
If you not like this circuit you can look others circuit more below.
- High power supply regulater 0-30V 20A by LM338
- High Current Variable Voltage Regulator 2-36V 10A
- Amplifier power supply using High Current Transformer
- 10A DC Supply FIX Regulated by IC 78XX and MJ15004
- 1-20V 10A adjustable dc power supply by LM338
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