This idea is based on an unregulated wall adapter/ transformer with DC voltage of 9V/300mA for regulating three outputs of voltage: 5V, 9V and 12V.  However, the unregulated output transformer is about 15Volt for supplying it to each input of the three regulators (Fig. #1).  Remember that you can use an unregulated wall/adapter from 9V to 15V for obtaining an input in the voltage regulators from 15V to 25V respectively and so with a good selection of amperage in your unregulated wall/adapter, you can use this electronic device as a charger too.

The Power is equal to Voltage times Amperage.  That is, P=VxA=Watts
For example, if you need to your cell phone 5V, 0.7A,, you will require 5x 0.7= 3.5Watts.  Then, your wall/transformer should be of at least 3.5 Watts.

Also, the DC Power Plug or Jack should be connected of the form as it's showed in the Fig. #2 for drawing the terminal positive and negative. 

It's important you realize that kind of unregulated transformer you are using for reading its specifications because the type of transformer must be with center positive for matching with the connection of  the DC Power Plug or Jack of this project. 

In contrary case, you should invert the connections of  the DC Power Plug or Jack.  That is, if you have an unregulated transformer with center negative, the terminal negative will be at center by having that invert the current connections for looking as in Fig. #4.

Let me show through a sign in the Fig. #4 that those connections aren't used in this project.

But, for this project is used an unregulated transformer of center positive (Fig. #3) that match with the connections propose and showed on the Fig. #2

Although the power jack looks of natural way in the picture showed after the fig.#4, in the last picture showed in this step we can note the identification of the connectos are A, B and C for connecting A and B as terminal negative and C corresponds to the terminal positive of our power jack male cited.

Step 1: Bill of Materials

1 PCB of 2.8"x3.7", protoboard
3 Heat sink, TO-220
1 7805, 1A
1 7809, 1A
1 7812, 1A
1 Switch Rotary Shaft Solder Lug 4 pole, 3 position or any 3 position with 2, 3 or 4 poles.
1 Knob, 1/4" shaft, 24mm, black, w/set screw
1 Jack, DC power, male
1 AC/DC unregulated wall adapter/transformer (9V, 12V or 15V) from 200mA to 2A and it matched with your needs of Power.
1 Panel Meter, LED Voltage, Blue, 4.5-30Volt, 3-Digit, Jameco Part: 2152323
2 Connector terminal block 2 position
4 .1microF, 50V ceramic capacitor
3 Capacitor, Radial, 1microF, 25V

Or, you can eliminate the 2 Connector terminal block 2 position while you add a slide switch and an enclosure for your project.

Step 2: Install the Jack DC Power Male

The Power Jack Male should be connected between the connections A and B for obtaining the terminal negative, and the terminal positive is drawed of the connector C.

Th rest of the pictures show as mounting the component on the PCB.

Or, you can leave free the component for being connected with the slide switch.

Step 3: Install the Voltage Regulators and Capacitors

It's important to note that each voltage regulator and its capacitors constitutes a basic system and the three voltage regulators form the main part of this project. 

These voltage regulators receive the same voltage that is about 15 Volt, such voltage is the input supplied to each voltage regulator by the AC/DC wall adapter/transformer.  

Of this manner, the regulators provide through their outputs the voltages of 5, 9 and 12 V because they count witn the enough voltage for regulating it and obtaining the adequate output accords to this project..

Step 4: Install the Heat Sinks and Connector Terminal Blocks

In this step, you need to install the heat sinks and the connector terminal blocks because the first dissipate the hot that the voltage regulators provoke with their operation and the connector terminal blocks permit to access the outputs of each voltage regulator will supply the invariable voltages of 5, 9 and 12.

Step 5: Wire the Rotary Switch and Panel Meter

In this step, wire the rotary switch and panel meter for forming that perfect couple that permit to select the voltage wished and reading the voltage on the panel meter. 

When you select the first scale with the rotary switch, you select 5Volt and can read 5Volt on the panel meter. 

The first scale is defined with a line on the knob that is the first position in this type of switch while the second scale once selected with rotary switch will permit to read 9Volt on the panel meter. 

Finally, the last scale or third position defined by the line marked on the knob we will permit to read 12Volt on the panel meter.

Step 6: Complete Your Project

In this step, complete your project. That is, connect the panel meter and rotary switch with the rest of the circuit.

Once you assemble the whole project, you need to plug in the AC/DC wall adapter/transformer into the power jack male.

Next, you have to plug in the AC/DC wall adapter/transformer into your home AC power supply.

Or, you can use a PCB smaller than that you are using now.

Step 7: Use DC 5V, 9V and 12V

In this step, you need to plug in the AC/DC wall adapter/transformer, with the rest of the circuit, into your home AC power supply.

If you want to read 5V on the panel meter, you should select the first position of your rotary switch.

If you want to read 9V on the panel meter, you will have to select the following scale of your rotary switch.

If you want to read 12Von the panel meter, you will select the third position of your rotary switch. 

And complete your project!!!
<p>This project can also be seen in Jameco Electronics at:</p><p>http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&amp;storeId=10001&amp;productId=2182661&amp;catalogId=10001&amp;CID=CLO</p>
<p>LEATHERWORKING classes are now free in this site.</p>
<p>BREAD classes are now free in this site.</p>
<p>PHOTOGRAPHY classes are now free in this site.</p>
<p>CANNING PRESERVING classes are now free in this site.</p>
<p>WOODWORKING classes are now free in this site.</p>
<p>CONCRETE classes are now free in this site.</p>
<p>GLUE classes are now free in this site.</p>
<p>MEAT classes are now free in this site.</p>
<p>WEARABLE ELECTRONICS classes are now free in this site.</p>
<p>RASPBERRY PI classes are now free in this site.</p>
<p>LASER CUTTING classes are now free in this site.</p>
<p>LAMPS classes are now free in this site.</p>
<p>CNC classes are now free in this site.</p>
<p>3D PRINTING classes are now free in this site.</p>
<p>Robots classes are now free in this site.</p>
<p>Electronic classes are now free in this site.</p>
<p>Arduino classes are now free in this site.</p>
<p>LEDS &amp; LIGHTING classes are now free in this site.</p>
<p>This project is for you.</p>
<p>Thank you for viewing this project.</p>
<p>I enjoyed developing this project.</p>
Is it possible obtain 12 volts from a 9 volts battery using a 7812? I don't need at least 14 volts to obtain 12 voslts from a a 7812?
No, you need at least 2Volt more of the voltage that you want to regulate because it's impossible by taking 12 apples where there are 9 apples only. <br> <br>
You can get a higher voltage from a lower input voltage but you need to use a DC to DC converter circuit. Which is different than a linear voltage regulator. The &quot;Joule Thief&quot; projects on this site are one way people do it. It is a simple switch mode power supply.
<p>Than you!</p>
Its not even possible for a 7809 to produce 9V with only 9V going into it.
You need at least 2Volt more in its input for obtaining the adequate voltage. It's important to note that the project's diagram shows a common connection for all inputs of the voltage regulators. Then all of regulators receive the same voltaje or about 15Volt.
<p>Happy New Year. I am glad to know you are professional technician in the LED digital display panel. As a professional manufacturer of 7 segment LED digital display, we would like to provide free samples for your design.I am Judy. you can add me in skype:arkjudy, or email: wangql@arkch.com</p>
Once you set the knob in the rotary switch, it should be with the line marked on the knob by pointing the first position or the beginning of the rotary switch without turning it and with this you will read 5Volt on your panel meter. For the following two positions, you will read in order 9 and 12Volt on your screen. <br>Thank you for your comments <br>
Your schematic does show where the switch and screen hook up to.
I would suggest actually giving some written instruction in all steps. The pictures don't always speak for themselves. If you want to have something featured or get a lot of attention you need to have a good writeup to go with it. <br> <br>If your basing this on a 9V wall wart how do you expect to get 9V and 12V on the output. The 7809 needs a minimum input voltage of 11.5V to be able to produce 9V on the output. The 7812 needs a minimum of 14.6V to produce 12V on the output. There is no way the 9V wall wart will support those voltages.
As the wall adapter/transformer is an unregulated one and its output is about 15Volt, it can regulate 12V. Also, there is a common connection for all of inputs of the voltage regulators (check the project's diagram). Therefore, all of regulators receive enough voltage for regulating its output correctly.
BTW if you have measured the wall wart with a meter and your getting 15V that is what it outputs when it doesn't have a load. I suspect that is what your basing all of this on. Had you mentioned that in the writeup then it would prevent some confusion. But you need to understand that when you put a load that is within 75% of the max available amperage from the wall wart it will only output 9V. So your circuit will not work on the 9V and 12V settings.

About This Instructable




More by braulio777:4-Digit Yellow Binary Counter 2-Digit Green Binary Counter Green Binary Counter 
Add instructable to: