[Claudio] was working on a homebrew oscilloscope project when he started thinking about how unsuitable a standard breadboard is for a large-scale project. Rather than adding components on top of components until they became what he lovingly calls a “fragile, unforgiving crapstack”, he decided to build himself the Ultimate Breadboard.

He packed so much into his design, that it’s honestly hard to know where to begin describing it. Aside from an appropriately large breadboarding surface embedded in the center of the console, he added a power supply to the left hand side, which sits just below an Avr-Net-IO board. The right side of the console features an Arduino NG, and a pair of level converters. He also added some LED-based VU meters, a couple of 7-segment displays, an LCD display, an analog voltmeter, along with plenty of I/O connectors.

The Ultimate Breadboard might look a bit daunting at first, but it seems like an awesome setup on which to do any sort of prototyping. Be sure to check out the video below for more details and to see [Claudio] give a tour of the device.

[Dave] has an ASUS tablet PC with a little problem. The device is charged via the docking connector’s USB cable when plugged into a special wall transformer. The problem is that the wall unit tends to overheat, and is shut down by a thermister inside to avoid permanent damage. The word on the Internet is to drop it in a zipper bag and chill it in the freezer for a bit. Although this works, it’s not the permanent solution that he was looking for. Instead, he hit the parts bin and built his own power supply replacement without buying anything.

The device is simply looking for 12V on the power pin (pin 1) of the USB cable. [Dave] dug through his mountain of unused AC adapters and found one that fit the voltage and current specs of the stock unit. He also grabbed a dusty old motherboard and plucked the USB ports off of the back. A bit of protoboard makes for a good base to connect the AC adapter wires to the ports, which was then covered with one big shrink tube. The result is seen above, and demonstrated in the clip after the break.

[Giorgos Lazaridis] needed an AC adaptor for his Canon PowerShot camera. He hit eBay and was excited to find this branded adaptor for just five bucks! It works and, even though it would sometimes reboot his camera if the cord was twisted around in the jack, he was satisfied that it did what it was supposed to.

That is, until one day he observed some very peculiar behavior while taking pictures of a PIC circuit he was prototyping. When holding the camera and putting his other hand near the breadboard one of the status LEDs in his circuit began flashing sporadically. If he was using the camera with batteries instead of the adapter this didn’t happen.

His first instinct was to hook up the adapter to his oscilloscope and see what is happening on the power bus. The signal is incredibly noisy. Shockingly so. [Giorgos] cracked open the case to see what is going on with the power supply circuit inside. You simply must view the video after the break to see the horror-show he found. The board is poorly soldered, components are not properly seated in their footprints, and our favorite is when [Giorgos] points out a squiggly trace which takes the place of the smoothing inductors.

Have you documented your own fake electronic hardware finds? We’d love to hear about them.

Make your next project solar-powered with this charging circuit. It’s completely through-hole, and there are no microcontrollers that need to be flashed. If you can source parts and are handy with a soldering iron building this will be a breeze.

Both the maximum system voltage and the low voltage drop out are configurable. After assembly, you just need to attach a regulated power supply to the load terminals. Tune the power supply to the max voltage and turn a potentiometer until an LED comes on, then repeat the process for the drop out voltage. Board artwork for the two-sided PCB and a schematic are available from the page linked at the top. If you’re not into etching your own circuit boards you can buy one for around $10.

[Thanks Murray]

[Quinn Dunki] got tired of messing around with wires when connecting things to her benchtop power supply, so she built herself useful little power bridge that plugs directly into any standard breadboard.

The board is small and simple, but quite useful all the same. It was built to power both sides of the breadboard, and it can be easily switched between an unregulated power supply and a regulated 5v supply. An ammeter can be attached to the board via a pair of pins she set aside, allowing her to easily measure the current draw of the entire circuit.

We think her “Juice Bridge” would be very useful to anyone who frequently prototypes on breadboards. In fact, it would be a fantastic beginner project since it involves etching and developing PCBs as well as some simple soldering, while resulting in a handy takeaway tool at the same time.

If you want to build one of your own, [Quinn] has the schematics and Eagle PCB files available for download on her site.

[Guido Socher] built himself a great little bench power supply that’s able to put out 30 Volts at 2 Amps.

Instead of taking the easy way out by putting a few taps on an ATX power supply, this project was built around a generic 24 Volt laptop power brick. An ATmega8 generates a PWM signal that is sent though a low-pass filter, allowing everything to be very precisely controlled. This DC signal is then sent through a BD245 power transistor to bring everything up to the desired output. [Guido Socher] included a USB port for computer control of everything, and the final project is something we’d be happy to have on our bench.

We’ve seen a few computer power supplies converted into a bench power source, but we’re impressed with [Guido Socher]‘s build log. It’s not often we see a hack that goes over the theory of operation, and the end product is very nice (and functional) too.

When dealing with electronics you need 1 key thing, electricity. For quite a while now if I needed 5 volts I would just grab my homebrew arduino, but that is not always handy and its tethered to the pc and it does not have 3v. If I wanted 3 volts, now I am digging around looking for my UBW32 which does have 3v3 but now I have a 50$ microncontroller with very small regulators (so therefore only small loads) dangling around just for power, and its a mess.

So I need just a board that takes some DC from a wall wart and regulates it to usable voltages, and I set about to make it. This regulator board puts out +5, +3.3, variable and negative variable voltages, is pretty easy to make, and make a nice addition to the bench. (until I can get a real bench supply someday)

Now I know this is not ground breaking hackery, but I hope it helps someone out there, join us after the break to see what’s going on.

First up, parts! I started by reviewing the datasheets for the 3 regulators, and pretty much throwing most of their advice away as most of this was scavenged parts. Beggars can’t be choosers.

That works mostly okay, but due to my resistance choices on the LM317T I am loosing a bit more (about an extra volt!) than I should be in the regulator. I used 100 ohms and 1khoms for the voltage adjustment … 120 and 2k or 240 and 5k would have been a much better choice, if I had those parts on hand.

But this is what I ended up using

1*SPST toggle switch

1*LED of your choice and appropriate resistor for 5 volt operation

3*Silicon rectifier diodes (I am using 1N4001′s but most would do fine)

2*47uf capacitors with voltage ratings higher than ~16 volts (I am using 50 volt caps)

1*10uf capacitor (its for the 3.3 volt line so anything more than 3v will work)

1*4.7uf capacitor (again I am using a 50 volt)

6*100nf ceramic capacitors (code 104)

2*100 ohm resistors

1*1k ohm resistor

1*1k ohm trimpot

1*7805 in a TO220 package

1*3 volt regulator in a TO220 package (I am using a ST “LD33V” though its not common)

1*LM317T in a TO220 package

1*555 timer

4*Dual terminal/ screw blocks

1*Large 3 position heatsink or 3 normal TO220 heatsinks

Wire, solder, and a 2 position jumper

More or less voltage comes in is filtered a bit with capacitors and is fed to the 7805 and 317T, the 3v3 regulator is wired to the output of the 7805 (along with the LED) so it does not have to drop a bunch of current and not run hot with minimal loads. Keeping in mind there are 2 regulators connected to a wall wart this thing in theory could suck up to 2.5 amps out of your supply so you either need a wall wart that can handle it or be very mindful of how much current you are drawing.

Next is the schematic .. not much to say here its a schematic… (click for large version)

Update: fixed the backwards diode

Finally I have to make the thing, I choose perf board with copper pads on one side, and uninsulated 22 gauge solid tinned copper as I find this way to be pretty easy as long as the layout is not too complicated.

Construction starts by mounting the regulators to the heat sink. I got this heat sink and many of the capacitors out of an old dead PC power supply. It is pretty big and should do the trick just fine, but there is a catch. Each of the regulators mounting tabs go to different functions, so unless I want to connect the outputs of the 3v3 regulator and the LM317T to the ground of the 7805 I am going to need either separate heat sinks or some silicon pads and nylon washer isolation hardware which my power supply was gracious enough to provide. (only after I threw them away and had to dig in the garbage for 20 min)

Here is a shot of the power input and 7805 all wired up and tested working.

Another shot with the 3v3 regulator wired up and tested working.

Another shot with the 317T wired up and tested working.

And finally the 555 voltage inverter is in place and working. While they make voltage inverters and I have a 5 volt one somewhere I rather like the idea of having one that can be hooked up to the 317 because I really don’t know if I will need -12, or -5 or anything in between.

Keep in mind this is a kludgey way to make a negative voltage, and it will not be balanced with the positive output of the 317 (you loose 0.7 volts or more in the diodes). Also it takes a few seconds before it stabilizes on a voltage, so start low and stop a little short as it will continue rising for a few seconds. You might be able to minimize that by using a lower value capacitor on the 555′s output, right now I am using a 47uf but I have seen everything from 10 to 470 depending on which schematic your looking at.

Anyway here is the final product and I am ready to rock. You might notice a jumper block on there and that is to cut power going to the 317. With the losses due to my resistance choice and the 555 timers output, that part of the circuit draws about 37ma, the 7805, led, and 3v3 regulator only draws 36ma (20 for the led). So if you’re not using it why bother adding the additional load to your power supply?  I may go back and tweak that.

Thanks for looking!

Instructable user [EngineeringShock] got sick of buying batteries for his devices all the time and has instead opted to build himself a super capacitor bank that can be used to power common household items.

His “forever” rechargeable capacitor bank is made of two large super capacitors rated at 400 farads apiece. It is charged through a LM317-based charging circuit that is adjustable to allow for slow or fast charging, the latter of which he admits, is slightly dangerous.

Since the super caps are only rated at 2.7 volts, they are wired through a DC-DC booster circuit that allows him to adjust the output voltage from 4.3 v to 34 v. The adjusted voltage is then passed through a digital display that allows him to see what the output voltage is at any time.

He says that the super cap bank can power his computer’s speakers for about two hours before requiring a recharge, which takes just a few short minutes, depending on how he is charging them.

While it’s not exactly cheap, the capacitor bank could be useful for those requiring quick portable power for relatively short periods of time. If we were to build one ourselves, we would likely fit all of the components into a small project box to protect the caps from accidental discharging, and top it off with a couple of solar cells to charge it for free during the day.

Keep reading to see a quick video demonstration of his super cap “battery” in action.

[Punish3r] wanted to have power for prototyping on the go. What he came up with is this little thing above. Inside you’ll find common components that let the unit provide 10 amp hours of current with a 12V 500mA output.

The storage capacity is provided by a dozen Lithium batteries. These 3.7V cheapies are wired in parallel behind a protection board. For charging and discharging, a Sparkfun LiPo charger board was used, taking care of all the work necessary to top off the batteries using a wall-wort. The final piece in the puzzle is a boost converter that provides the regulated 12v connected to the red and black banana plug receivers on the bottom of the case.

This is very much a plug-and-play design… just make sure you hook the parts up correctly and you’re up and running. We would love to see a roll-your-own boost converter circuit that include a switch or dial that lets you select common PSU voltage levels. If you’re going to the trouble to make your own board you might as well incorporate the charging circuit at the same time.

[Thanks Paul]

Concerned with your project’s power consumption but don’t want to constantly leave an ammeter wired in series with your power supply? [Rajendra] feels your pain and has recently documented his solution to the problem: a variable-output bench top power supply that clearly displays load current consumption among other things!

Everything is wired up in a nice roomy enclosure that has front-panel access to ±5V and variable outputs, an adjustment potentiometer, and even an input for an integrated frequency counter. A PIC16F689 MCU runs the show and displays the variable output voltage and current on a 16×2 character LCD. Although clearly useful as is, the PIC has plenty of I/Os and muscle left for future expansion and a capacitance meter has already been hinted at as and addition for version 2!

The power supply itself is pretty straight forward and uses 7805 and 7905 voltage regulator ICs to provide ±5V DC output. A LM350 IC also provides a variable output of between 1.25V and 9V – limited to 3V below the input voltage, in this case a rectified 12V from a standard transformer.

In order to measure current, a shunt of low but known resistance is wired in series with the output. In high-current applications these shunts are typically made of alloys that maintain a fairly consistent resistance across a wide temperature range. Since the currents in this project will be limited to a few Amperes there shouldn’t be too much resistive heating going on, and a 5 foot length of 22AWG wire wound into a coil provides a convenient and low-cost alternative. The voltage dropped across this resistance can then be measured and is directly proportional to the current flowing through it as related by Ohm’s law. This voltage drop reduces the voltage presented to the actual load as compared to the output of the regulator IC where the voltage is being measured in this case, but is accounted for in the code before the value is displayed on the lcd.

Full source code and schematics are provided and plenty of time was devoted  to explaining some of the trickier concepts such as amplifying or decreasing signal amplitudes to levels suitable for ADC input and how to use a prescaler to count high frequencies exceeding the PICs own 20MHz oscillator. Also, although this design limits the current sensing capabilities to 1.2A, alternatives to the op-amp stage are discussed that could increase this limit.

Overall this project should be very approachable to even novice hackers and is a great way to practice many basic electronic concepts. What makes it even better is that the end result is a useful tool for future prototyping.

[Viktor] decided to replace his old power hungry home server with a model that is much easier on the old electric bill. The new motherboard uses an Intel Atom chip and consumes far less power than its predecessor. He figured there was no reason to use a bulky ATX power supply when all he needed was 12V for the mainboard and a pair of 5V rails for his hard drives, so he decided to build a PSU himself.

He sourced a 100VA toroid transformer as the basis of the power supply due to its popularity with audio amp builders, adding a standard bridge rectifier and smoothing capacitor before regulating the DC output. A pair of switching regulators were added, one for the 6A, 12V, and a second for the 1.5A, 5V supply. The motherboard only requires about 18W at full tilt, so the PSU should be more than sufficient for his needs.

Schematics and board layouts are available for free on his site, if you are in the market for your own DIY low-power PSU.

Looking for more build to suit electronics?  Check out this DIY amp we featured just the other day.

[Thanks, Chris]

[Will] had a cheap power supply sitting around, and decided to turn it into a full-featured benchtop PSU. Inspired by some of the other benchtop supplies we have featured in the past, he decided that he wanted his PSU to be more than just a simple-looking box sitting on his work bench. Taking some cues from PC case modding, he put together a unit that is not only very useful, but also quite sharp looking.

The frame of the case was crafted from aluminum angle, while all of the other flat surfaces were made using black polycarbonate. He installed the standard 12v, 3.3v, and 5v terminals you would expect from any benchtop PSU, complete with an LCD display showing the voltages provided by each rail as measured by an Arduino stationed inside the case. Additionally, he installed a variable terminal capable of providing 1.3v-30v, along with its own LCD display. The most unique feature is the multimeter embedded in the front of the case, which makes it virtually impossible to lose.

The case is finished off as you might expect, if you have seen any of his previous work. It features LED lighting on the inside, large fans on either side of the case for optimal air flow, and a pair of machined aluminum handles.

Be sure to check out the quick video below of the PSU being powered on.

Here’s a fancy way to convert an ATX powers supply into a bench supply. [TG] didn’t just cut off the motherboard connector and add banana plugs, but improved the functionality. Right off the bat you’ll notice that he’s added a control panel. There is an Ammeter and Ohmmeter to let you know what the unit is putting out. He added an MIC29152WT adjustable voltage regulator so that he’s not limited to the fixed voltages of the psu. As a final touch he added an external voltage probe which can be used with the flick of a switch. It’s no replacement for a proper bench supply, especially since it doesn’t have adjustable current limiting, but it’s a nice improvement upon previous psu hacks.

Powering your gadgets generally seems like a necessary evil. To help with this [Felipe La Rotta] made a really nice bench power supply using a PC power supply and a LM317 adjustable voltage regulator. PC power supplies are an example of a switched power supply(more on that later).  The LM317 is a type of linear voltage regulator that allows for adjusting the output voltage by varying some resistors. Whats the best way to power your circuits? well that depends…

Usually the first step for powering your product is batteries, they are easy, cheap, and can be strung together to get a voltage close enough to what you need (hey sometimes it doesn’t really matter that much). But What do you do when your super picky sensor only accepts 3.3V? A quick and dirty voltage divider will bring the battery voltage down to 3.3V.

Unfortunately the more the sensor pulls on the divider the farther from 3.3V it will be. This is the basic principle of load regulation. The general idea is that the more current you need the farther off your voltage will be. Well what if there was a buffer in there so that the circuit doesn’t affect the voltage divider at all.  Maybe something like this.

But then after a day or so the sensor isn’t sensing very accurately.  The voltage going into the sensor is now only 2.8V. This is the second problem with a voltage divider; it’s sensitive to the supply voltage. This is called line regulation.  Basically as your battery voltage drops so will your output voltage.  What would be useful is a voltage that doesn’t change, that way the output could be based on that.  Here is where the Zener diode comes in.  The voltage across a Zener is set when it’s made and it varies very little with respect to current (after it gets into breakdown).  So now the Zener can be used as a reference, and then the OP-AMP buffers that to the output.

This is the general idea of how voltage regulators work.  Luckily there is no need to make one of these for every project because companies sell them in nice little 3 pin packages. All you have to do is hook up ground, the unregulated voltage, and it will regulate the output on the third pin.  Linear regulators address both load and line regulation and everybody’s happy, right?  Well maybe not.  Say a regulator takes in 9V from the battery and supplies 3.3V to a circuit and the circuit responds by drawing in 500mA.  This means that the power going into the regulator is 9V*500mA = 4.5W and the power out of the regulator is approximately 3.3V*500mA=1.65W.  What happened to the other 2.85W? It was burned off as heat inside of the voltage regulator. That means only about 57% of the power even makes it to the load; The rest is wasted.

Enter switched mode power supplies (like the one in your pc).  These circuits are made using inductors, capacitors and switches (transistors) in order achieve much higher efficiencies.  They work by constantly adjusting the current through an inductor resulting in higher or lower output voltages.  Switching supplies may be more efficient but they are also more complex, harder to implement, and can be rather noisy circuits.

so generally:

voltage divider: very easy, cheap, bad regulation

Linear voltage regulators: easy, good regulation, poor efficiency

switching power supplies: hard, noisy, good efficiency

This is a bench power supply with adjustable voltage and current limiting. [Sylvain's] creation can regulate 0-25 volts while sourcing 0-5 amps. Current limiting is a nice feature as it will allow you to test your prototypes to ensure the power regulator you choose will not be over or underpowered.

This supply is really a two-in-one. The case has two separate circuits so that you can have different power rails going at the same time. There is a microcontroller involved, but the ATmega32 doesn’t do anything more than measure the voltage and amperage and drive the graphic LCD screen. Two potentiometers are responsible for setting the voltage and limiting the current.

[Thanks Sargonout]