# Tiny Breadboard 5v PSU (with Two Output Modes)

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This tiny discrete 5 volt PSU is ideal for breadboard projects. You can stick it between the break of the power lines on your breadboard. With a jumper switch you can provide 5 volt for the whole power line or 5 volt on the right side and the input source on the left side. Which is very handy for projects who needs a voltage regulation. For example stepper motor controlling circuits; 5 volt for logic level and 12 v for the motors or relay controlling or RGB LED controlling, etc. The tiny PSU can be supplied by any regular AC/DC converter(8-18v).
I'm from the Netherlands so I'm doing my best writing this in English! And this is my first Instructable so any comments or questions are welcome.

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## Step 1: Parts and Tools

The parts of the tiny PSU are common. I've made a picture of it and here's a list:

1) Voltage Regulator 7805CT (datasheet)
2) 150 Ohm Resistor
3) 3mm LED
4) 100 µF, 25 Volt Electrolytic Capacitor
5) 10 µF, 63 Volt Electrolytic Capacitor
6) 100nF Small Capacitor (label is usually 104M, for more info of Capacitor color codes, go here
7) 2-pin Screw Terminal
8) 7 pin connectors
9) 1 jumper
10) A piece of stripboard
11) Some wires (use hard wires which you can bend)

Look at the picture for the tools i've used, they are also pretty common.

## Step 2: The Schematic

The schematic I've designed is a basic voltage regulation circuit with a extra option. As you can see in the picture there two outputs via the pin connectors; JP1 and JP2. JP1 always gives an output of 5 volt and the output of JP2 can be selected by JP3: if we place a jumper onto pin 1,2 of JP3 the output of JP2 will be the same as the source input and if we place the jumper onto pin 2,3 of JP3 the output of JP2 will be 5 volt.
So the finished PSU will be plugged into the breadboard above the break, providing 2 different or one output voltages. I made an illustration of this to make it more clear for you. Note that your breadboard also must have an break in the power lines. And if it does not you can adjust the PSU to make it only provide 5 volt for example. But I guess it is still a nice PSU because of its small size.
And don't forget to put a wire from the top power line to the bottom power line of your breadboard, you must add wires at both sides of the breadboard, as shown in the breadboard example picture.

## Step 3: Prepare the Stripboard

I made a illustration of the circuit into a piece of stripboard, which makes the details very clear.
First you saw out a piece of stripboard, 8 dots in the horizontal copper line and 7 vertical. Then you make the cuts in the copper paths as shown in the illustration. You can use a stanley knife for this. Just make sure no copper is touching each other and make the cut width enough (something like 1mm) so that the solder thin will not drip over the cut during soldering. I didn't take picture when I was building mine, sorry for that, but I added a picture of the bottom of my finished one, maybe it makes it more clear. Alright! when you are done fixing the stripboard it is time to go to the soldering part!

## Step 4: Soldering

When you start soldering begin with the wires, then small components and then the bigger parts. Use your helping hands. And if you find it hard to keep components in place upside down during soldering, bend the end leads of your components so that clamp a little in stripboard. If you find it really hard, just glue all the components with super glue onto the stripboard, but don't glue your fingers you need those! I Added a picture of the bottom of my finished one so you can see how I soldered it. So now solder it all together!

## Step 5: Test and Done!

Stick the tiny PSU into your breadboard. Connect a power supply into the screw terminal and plug in a multimeter into the breadboard power lines. I hope you did it al good and now have yourself a nice tiny PSU! I hope you've enjoyed my instructable. If you got any comments or questions, sent me a message or leave a reply.

Warm regards,
Stein Roeland

Amsterdam, The Netherlands

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## 8 Discussions

I am curious what is the purpose of the C2 and C3 together?  I understand having one capacitor as a filter but I see C2 and C3 in other setups also what is the purpose for that?

Thanks!

One capacitor filters out high frequency noise, and helps prevent oscillation of the device, and the other low frequency noise or ripples

Very neat - A great first Instructable.  No problems at all with the English.  If only all native English speakers communicated that well.
Just a couple of points :-
(I find the Farnell site extremely useful for data sheets.)
If you're pulling anywhere near 1A, or using a voltage in the 'teens that 7805 is going to get rather hot.  How about finding a simple way to mount a heatsink above the device for those situations.
What software did you use for the stripboard layout - was it Lochmaster?

4 replies

Thanks for that! Nice to hear!
I changed the link of alldatasheets to the one you gave, thanks for that.
And I think it would be possible to mount a heatsink, maybe the 7805 must be moved to edge of the board where the caps are, and a little adjustment in the circuit board, so that the 7805 can be turned around with his back to edge. Then you can hang a little strip of aluminum onto it... I will make an extra step for that when accomplished.
I used DIYLC, here's a link, for the stripboard. I used the multi platform which is in java, not the best but it works. The library contains some basic components and I took it trough photoshop where I added text en lines.
I don't understand what you mean with your second reply...? You mean that the input voltage must be at least 3v above the output of the 7805? Or something else...?
cheers

Capacitors have a maximum working voltage, which must be higher than the voltage you're going to use it with.  Common WVs are 10V, 16V, 25V 50V etc.  If you use a 100uF 10V or 16V one at the input you may exceed its rating.  Best to specify it as 25V so it will work over the full range you've given (8V to 18V).

Just one more thing;  You should mention to use a working voltage of at least the supply voltage for the input capacitor.