Transformerless power supply 12v 2a

transformerless power supply 12v 2a

As you might expect, I have several power supplies that have more than enough capacity to power my new KN-Q7 transceiver. In short, I wanted a simple power supply which I could dedicate to this new transceiver.

All Rights Reserved. In order to operate the new transceiver, I needed a power supply. I began by building a power supply with a linear regulator, and later, I modified a laptop power supply. The details are described below. In addition, I have described how I connected a really cheap computer microphone headset to the KN-Q7. A tuning aid to help adjusting a manual antenna tuner is also described in detail here on my website. I hope to add some details of my new antenna tuner, complete with it's simple SWR meter, soon.

The Design The design is simple and well-proven although it varies from the traditional approach to allow the 2N to be directly mounted on the chassis or heatsink without the usual insulating washer I had a really cheap 12V car battery charger in the workshop which I thought could be easily modified to make a suitable power supply.

I also found that the cheap charger transformer induced some low level hum into the transceiver when I sat the transceiver on top of the supply. These consumer products seem to have a lifetime shorter than a mosquito!

The transformer looked big enough, and I measured its secondary voltage at 19VAC no load. A bit high, but under load, it dropped to about 16VAC. That would be OK. Linear Regulator The regulator section of the power supply is a slight variation on the standard regulator design shown in the datasheets for the LM 12V 1A regulator. To increase the current capability of the regulator, the datasheet shows a circuit using a high power PNP transistor wrapping around the If the circuit is inverted, and a V regulator LM is used instead, you gain two advantages.

However, more is better, and besides, I had this larger capacitor on my shelf along with all of the other parts. The audio system transformer has a copper band around the outside of the windings, and that effectively prevents the induced hum problem noted with the cheap charger transformer. It was arranged in a very similar manner to that shown in the schematic. I chose not to change this, although I think there is some benefit from relocating the red LED to the actual output of the power supply.

As it stands, with my transformer, the green LED acts as a current indicator. Because, on current peaks, the DC input to the regulator falls below the voltage required to keep the combination of the 12V zener diode and 2V green LED fully conducting.

It dims nicely at about 2A, and goes out at about 2. I also had to add a higher rated bridge rectifier to suit my new transformer, using diodes also salvaged from older equipment, and I added the slow blow fuse to the original charger PCB in place of the original, unwanted, glass-encapsulated thermal breaker.

All quite easy to do. Operation In service, the power supply worked really well. If you plan to talk longer than this, then use a metal box for the power supply and bolt the 2N or similar to the chassis. A SMPS like this is ideal to take on holiday because they are so light.

However, they can generate a lot of RF noise. And that proved to be a problem with the one I first tried to use. After adding lots of extra filtering and getting nowhere, I tossed it aside and went to find another one. I visited a recycling center in my town, and bought an old laptop switch mode power supply. The most difficult task was to carefully break apart the plastic power supply shell.Source: goo.

Custom applications will work a 3. In order to test the electrical resistance of insulators, it is necessary to have a voltage source. The required output voltage. Electronics Projects Tags Contact. Electronics Circuits.

Electronics Projects. Tags: power electronic projectssmps circuitssmps projectssmps schematic. They are cheap and uncomplicated. However, these programmers have lost their versatility because Atmel has introduced new microcontrollers, programmed with PDI and TPI interfaces. The programmer presented in the article is universal, it will be useful to both older and newer AVRs. List of AVR microcontrollers depending on the type of programming interface On the output side, the AVR-ISP MKII programmer has a special buffer by which it is possible to program microcontrollers fed with different voltages, whereby the programmable microcontroller can be energized by the programmer or the voltage of the programmed system.

Choosing the supply voltage enables the jumper. The programmer communicates with the computer using the USB interface. The computer can run under Windows XP, Vista, 7.

Electronic Circuits projects, circuit diagrams. This site uses cookies: Find out more. Ok, No Problem.The trimmer P3 adjusts the minimum current limit. P4 adjusts the maximum output voltage. After the final adjustment you may replace the trimmers with standard resistors. Power transistor dissipates quite a bit of heat and thus require a heatsink with optional fan. We may use two or tree transistors in parallel with emitter resistors to achieve more power. The transformer must be W with VAC output voltage.

Dual Adjustable Power Supply. The circuit is based on LM positive and LM negative voltage regulators. LM series of adjustable 3 terminal regulator is capable of supplying in excess of 1. A constant current source source can supply a fixed current to a load regardless of input voltage or load change. The LM is quite useful as a constant current source, works on a wide input voltage range, from 3V up to 40V.

Solar energy is renewable, free, widely available and clean form of energy. It is considered as a serious source of energy for many years because of the vast amounts of energy that is made freely available, if harnessed by modern technology.

Many people are familiar with so-called photovoltaic cells, or solar panels, found on things like spacecraft, rooftops, and handheld calculators.

The cells are made of semiconductor materials like those found in computer chips. When sunlight hits the cells, it knocks electrons loose from their atoms. As the electrons flow through the cell, they generate electricity.

In this project, we are building a power bank which harvests energy by using a solar panel. The energy gained by the solar panel is stored in a LiPo battery. Then the battery is used to supply a stable 5V which is used by USB gadgets. The power bank can also be charged by an external 5V source.

how to make transformerless power supply 230v AC to 12v & 5 DC #High amp 500ma

After many years of employing this ugly and clumsy bench power supply, I decided it was time to build something better, smaller and nice looking. It began as a variable power supply based on an LM 5A voltage regulator and external power adapter. LM's Data Sheet has several very helpful application notes and circuits. I chose one that illustrated variable output and included protection diodes.

Diodes are included to protect the regulator from damage in case the input is accidentally shorted to ground. This is a distinct possibility if using jumpers to attach it to the power supply. Also the output of station supply may be shorted if some other device fails. Without the diodes, if this happens, the capacitors will dump their charge back through the regulator. Since the current spike may be many amps, the regulator may fail.In this post we discuss 4 easy to build, compact simple transformerless power supply circuits.

All the circuits presented here are built using capacitive reactance theory for stepping down the input AC mains voltage. All the designs presented here work independently without any transformer, or no transformer.

As the name defines, a transformerless power supply circuit provides a low DC from the mains high voltage AC, without using any form of transformer or inductor. It works by using a high voltage capacitor to drop the mains AC current to the required lower level which may be suitable for the connected electronic circuit or load. The voltage specification of this capacitor is selected such that it's RMS peak voltage rating is much higher than the peak of the AC mains voltage in order to ensure safe functioning of the capacitor.

An example capacitor which is normally used transformerless power supply circuits is shown below:. This capacitor is applied in series with one of the mains inputs, preferably the phase line of the AC. When the mains AC enters this capacitor, depending on the value of the capacitor, the reactance of the capacitor comes into action and restricts the mains AC current from exceeding the given level, as specified by the value of the capacitor.

However, although the current is restricted the voltage isn't, therefore if you measure the rectified output of a transformerless power supply you will find the voltage to be equal to the peak value of the mains AC, that's around Vand this could be alarming for any new hobbyist.

But since the current may be sufficiently dropped level by the capacitor, this high peak voltage could be easily tackled and stabilized by using a zener diode at the output of the bridge rectifier.

The zener diode wattage must be appropriately selected according to the permissible current level from the capacitor. The idea is cheap yet very effective for applications that require low power for their operations.

Using a transformer in DC power supplies is probably quite common and we have heard a lot regarding it. Even if the current requirement for your circuit application is low, you have to include a heavy and bulky transformer making things really cumbersome and messy.

The transformerless power supply circuit described here, very efficiently replaces a usual transformer for applications which require current below mA. Here a high voltage metalized capacitor is used at the input for the required stepping down of the mains power and the preceding circuit is nothing but just simple bridge configurations for converting the stepped down AC voltage to DC. The circuit shown in the diagram above is a classic design may be used as a 12 volts DC power supply source for most electronic circuits.

However having discussed the advantages of the above design, it will be worth focusing on a few serious drawback this concept may include. Another drawback that certainly needs some consideration is that the concept does not isolate the circuit from dangerous AC mains potentials.

Therefore, new hobbyists must work with this circuit very carefully to avoid any electrical casualty. The last but not the least, the above circuit allows voltage surges to enter through it, which may cause serious damage to the powered circuit and to the supply circuitry itself. However in the proposed simple transformerless power supply circuit design this drawback has been reasonably tackled by introducing different types of stabilizing stages after the bridge rectifier.

This capacitor grounds instantaneous high voltage surges, thus efficiently safeguarding the associated electronics with it. PCB Layout for the above explained simple transformerless power supply is shown in the following image. Please suggest the best robust circuit with surge protector and advice any additional things to be connected to protect the circuits. Here the input capacitor 0.

12V, 2A Uninterruptible Power Supply

In this example it will be around 17mA which is just about right for the selected LED string. Therefore for 2 strings in parallel, the required value would be 0.

Similarly for 4 strings this would need to be upgraded to 1. Important : Although I have not shown a limiting resistor in the design, it would be a good idea to include a 33 Ohm 2 watt resistor in series with each LED string for added safety. This could be inserted anywhere in series with the individual strings. Now let's see how an ordinary capacitive power supply may be transformed into a surge free voltage stabilized or variable voltage transformerless power supply applicable for almost all standard electronic loads and circuits.

The idea was requested by Mr.Welcome to ETOP. Parameter table :. And inwe finished renewing the ISO quality. Our Certificates:. We can. Our packaging:. Business goal: Promote industry development, form complete industry chain and creat an international.

transformerless power supply 12v 2a

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12V @ 120mA Transformerless Power Supply

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transformerless power supply 12v 2a

Product Certification. CB Certified. Valid from until Time days 25 To be negotiated. Online Customization. Video Description. Our Services.Latest Projects Education. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Search Forums New Posts. Status Not open for further replies. I searched this 12VDC 2a transformerless power supply,but i was unable to find it Scroll to continue with content.

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Hi, I'd be glad to help you, but your specs are too vague for me to answer you. Also, tell me what the power supply load is what will it be powering? When you reply with that, I'll answer you with details. Regards, Kamran Kazem. Wendy Joined Mar 24, 21, If you are talking about trying to make a power supply connected to power mains without a transformer, well, I expect this thread to be closed shortly.

There is no safe way to make a power supply without using a transformer. Personally I recommend a wall wart. A DC - DC converter is one thing; a transformerless supply operated from the mains is another. Can the OP clarify? The use of a transformer is a MUST. There are circuits as SMPS that are small, but still use a transformer. You May Also Like. Continue to site. General Electronics Chat. Mar 31, Jan 6, Efficient, cheap way to step down 24v dc to 12vdc?

Dec 31, Oct 4, Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. C1, C2 is the electrolytic capacitor uF 50V is in parallel with the DC output 12v the other C3-C6 are also in parallel with the supply along with the uf ,so the Dc supply is filtered. Question 6 weeks ago. How did you choose the PCB? I mean how much current can it withstand? Is it possible to increase the current to 6 amperes?

I need a power supply to power up my TEC. How can I modify it to have an output with 6 and 2 amps output? If i use for designing 5V,2A power supply then any other changes needed in component values? If you like this then you might like one of the power supplies that I posted on this site. It is adjustable voltage, and current.

It is the variable current power supply which give output of 12V 1A-5A its a designed PCB Input is by 12V 5A transformer you can also increase the current rating of the power supply by using more no.

Add Teacher Note. I have designed the power supply on eagle. Did you make this project? Share it with us! I Made It! Embed Tinkercad Designs in Instructables by bekathwia in Websites. Large Motors Class 14, Enrolled.

Answer Upvote. Reply Upvote. Stefano 3 years ago.


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