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open-hardware-power-supply-queue Not Helpful 14 Helpful That Video looked like a software Constant-current failure more than anything. If you want to make changes or qeuue open hardware power supply queue design, Schematic files in. Electronics Enclosure. There are 2 16 pin headers connecting the 2 boards, and the important parts to access are in between the boards. You'll be follwing the same order Disconnect the exisiting wiring harness from the power supply by loosening the the screw on each terminal block and removing the wire.

Years ago I built a cheap dual-rail supply; it used a couple of linear supply kits from a local electronics store, and was put together with a mains transformer and a couple of voltmeter display panels. So, the aim of this project was to build a reasonably general-purpose, low noise, compact linear power supply that can be embedded into larger projects or could be used standalone.

It is intended to supply up to around mA at voltages selectable at design time, and power output can be up to 3. The final PCB actually contains two designs; a dual rail supply, and also a separate single rail supply. The two sections can be cut if desired, if all three rails are not needed in a project. Multiple boards could be used for additional rails. The photo here shows the dual rail portion of the board completed the single rail part of the board is essentially just a duplicate of half of the dual-rail portion, and is not fully soldered in the photo below.

The separate single rail supply is isolated, to help keep any microcontroller noise away from the analog circuitry. The voltage regulators are adjustable at design time through modification of component values so the PCB can be useful for various projects by altering the capacitor and resistor values, and selecting an appropriate transformer.

To summarise, here are the design specs, but as mentioned these values can be changed by altering component values:. The flattened top and bottom is normal; the mains supply is not always a perfect sine wave, and the transformer may be introducing some harmonics too. The output from the mains transformer is rectified and then any diode switching noise is filtered and the rectified output is also filtered using the large electrolytic capacitors to leave a DC waveform.

Any high frequency noise is reduced using ferrite beads, which present a high resistance to such noise content. The positive unregulated output from the circuit above goes to the positive linear regulator. This circuit is based around an LT integrated circuit. The datasheet was followed. The voltage is set using a couple of resistors, but if you wish to make changes then please consult the datasheet because some other part values such as capacitor C10 in the diagram below also need to be adjusted if the desired voltage is changed.

Note that the output voltage with the values shown is actually 14V, not 15V. The output current is set to mA maximum. The negative unregulated output from the bridge rectifier is fed to a LT based circuit.

Again the datasheet was closely followed. The output is V mA max with the values indicated. The portion of the PCB that contains the single rail power supply reuses the same design as for the positive rail. The values are changed though, because I desired to set this output to 5V. The current limit for the 5V output was set to mA with resistor R1. The render here shows what the PCB looks like for the dual rail design. The transformer output is connected on the left side.

The circular arrangement was originally intended to allow screwing directly over the center of the toroidal transformer for a very small footprint supply block, but toward the end of the PCB design layout I decided to just fit it alongside the transformer with screw holes on the corners of the PCB instead. The top half of this design implements the negative supply rail, and the bottom half implements the positive supply rail. Follow each cable from the power supply to the component to make sure that everything is properly unplugged.

Make note of where everything was plugged into for when you reassemble the case. Make a paper clip tester. You can use a paper clip to help test your power supply and trick it into thinking that it has been switched on. It is typically the largest connector for the power supply. You will be inserting the ends of the paperclip into the green pin there should be only one and a neighboring black pin.

Before you do this, double check to make sure that the power supply is completely disconnected from any power outlet, that it is switched off, and that it is not connected to any computer components.

The green pin is typically pin 15 on a pin chart. Insert the paperclip. Plug the power supply back into the outlet, and flip the switch in the back. Check the fan. This will let you know that the power supply is at least working. If the power supply does not turn on at all, double check your pins after unplugging and try again. If it still does not turn on, then it is most likely dead. You will need to perform the next test to ensure that it is outputting correctly.

Part 2 of Check the output through software. Check the readouts to ensure that they fall within accepted tolerances. If your computer does not work, skip to the next step. Shut down the computer. Turn off the power switch on the back of the power supply. Open the computer and disconnect all of the components from the power supply.

Follow the cables from the power supply to each component to ensure that everything has been properly disconnected. Test the power supply with a power supply testing unit. These are available online and from computer stores, and are not very expensive. This is typically the largest cable for the power supply. Plug the power supply back into the outlet and turn it on.

Your power supply should turn on automatically and your power supply tester will light up. Some power supply testers require you to turn on the power supply using a switch or button on the tester. Others will turn on automatically. Check the voltages. If any of the readings are outside that range, than the power supply is bad and needs to be replaced. Test the other connectors. Unplug and turn off the power supply between each test. Test the power supply with a multimeter.

Plug the paperclip into the green pin pin 15 and into one of the neighboring black pins. Plug the power supply back in and turn it on. Find a pinout chart for your power supply. This will let you know which pins provide which voltages. Set your multimeter to the VBDC setting. If your multimeter does not auto-range, set the range to 10V. Connect the negative probe of the multimeter to a ground black pin on the connector.

Connect the positive probe to the first pin that you want to test. Make a note of the voltage displayed. Check the voltages to make sure they fall within the tolerance threshold. If any of the voltages are outside of the tolerance range, then the power supply is defective.

Repeat the process for each of the peripheral connectors. Imagine you have a workbench setup running in a shed off batteries. Would also be handy to implement a safe shutdown command, where the supply sent out a warning to powered devices that the input power was about to shut off. It is even cheaper than adding an optically isolated usb port and cable.

I can see how some people might want to of course, and this PSU should be much help with that for all three of them. You add a linear regulator controlled by the DAC that was controlling the switching regulator.

Then you add another circuit which controls the switching regulator so that its output is x higher than the output of the linear stage. Not really, it is more complicated. A switching regulator operates at frequencies at which a linear regulator is not that good of a filter.

Easily, you would add a filter in between. I do support the idea of any instrument having a web interface. With basic things you have on a desktop such as zooming and window resizing you can easily make a simple display that gives you a control panel view of whatever you are doing with multiple instruments. I looked into this, there seems no way to take apart the smaller version of the supply without destroying it.

There are 2 16 pin headers connecting the 2 boards, and the important parts to access are in between the boards. The adjustment potentiometer tends to go quite far down off the nominal voltage.

Thanks for the suggestions! That should do nicely. Please be kind and respectful to help make the comments section excellent.

Comment Policy. This site uses Akismet to reduce spam. Learn how your comment data is processed. By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Learn more. I was looking to do exactly that. Thank you. Report comment.

I mean, who has a 50Volt wall wart plug pack lying around. I used to work for a telco. I never saw a 48 Volt supply that was less than three rooms big. Something like 3 kilowatt in 2 rack units.

It was not even deep. It is 48v w. I made a enclosure that you can 3D print if you want to use it. Works great for me! Im jealous. I like that you made a step level for it on your bench. What display panel does it use? I kind of need something with that aspect ratio and approx size. I have some switch mode modules as well. I have had several bench power supplies though I have never bought one. Making your first bench supply was more or less a right of passage back then.

Into the dual banana sockets I could plug in a lead to use unregulated voltage.

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