• Bench Power Supply Project

    Posted in: DIY Projects

    In this series we are going to go through the design and build process of a variable bench power supply.

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        DIY Bench Power Supply: #1 – Output Switch
        1. Output Switch

        In this series we are going to go through the design and build process of a variable bench power supply.
        In this video we take a look at my college power supply as this will form the basis of the design. Improvements to the design will be an output switch, initial current setting without dummy load, both coarse and fine voltage / current adjustment.
        I use the oscilloscope to view the switch on / ramp up / slew rate of the power supply switches.
        Future videos in this series will cover: “soft” output switch design, power supply design, enclosure / case design, printed circuit board (PCB) design and manufacture, analog and digital display options for current and voltage, breadboard to PCB design with DesignSpark by RS Components: http://www.designspark.com/
        Thanks to Tiaan for his “relay contact bounce” post:
        http://www.eevblog.com/forum/projects…

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        DIY Bench Power Supply #2 – Initial Circuit draft and parts
        2. Initial Circuit draft and parts

        In this series we are going to go through the design and build process of a variable bench power supply.

        In this video I draft the circuit diagram and parts list of my college power supply as this will form the basis of the design. Improvements to the design will be an output switch, initial current setting without dummy load, both coarse and fine voltage / current adjustment.

        Future videos in this series will cover: “soft” output switch design, power supply design, enclosure / case design, printed circuit board (PCB) design and manufacture, analog and digital display options for current and voltage, breadboard to PCB design with DesignSpark by RS Components: http://www.designspark.com/

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        DIY Bench Power Supply #3 – Circuit Troubleshooting – Pt 1
        3. Circuit Troubleshooting - Pt 1

        In this video I try a better approach to troubleshooting the Bench Power Supply Project circuit. I use DesignSpark (CAD) to draw out the circuit and then set it up on a breadboard.It does not work straight away…so time to troubleshoot and test…

        http://www.rs-online.com/designspark/…

         

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        DIY Bench Power Supply #4 – Circuit Troubleshooting – Pt 2
        4. Circuit Troubleshooting - Pt 2

        In this video I mange to get a fair bit further with the circuit troubleshooting for the for the DIY Bench Power Supply Project.

        It works barring a couple challenges to resolve.

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        DIY Bench Power Supply #5 – Circuit Design and Operation – Pt1
        5. Circuit Design and Operation - Pt1

        I go through the design and operation of the college power supply project. There is one minor error that still needs to be corrected but I think we are very close to a final design.

        Thanks to Peter Oakes (https://www.youtube.com/user/TheBread…) and Chris Gammell (https://www.youtube.com/user/contextu…) for their valuable input.

        This project will allow you to change the design parameters to suit your own purposes and learning through experimentation.

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        DIY Bench Power Supply #6 – Circuit Design and Operation – Pt2
        6. Circuit Design and Operation - Pt2

        I go through the design and operation of the college power supply project. There is one minor error that still needs to be corrected but I think we are very close to a final design.

        Thanks to Peter Oakes (https://www.youtube.com/user/TheBread…) and Chris Gammell (https://www.youtube.com/user/contextu…) for their valuable input.

        This project will allow you to change the design parameters to suit your own purposes and learning through experimentation.

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        DIY Bench Power Supply #7 – Circuit Design and Operation – Pt3
        7. Circuit Design and Operation - Pt3

        Next in the DIY Bench Power Supply series.

        Looks like I might have the circuit in its final iteration after finding the last errors. Subject to change after testing though 😉

        Parts list and circuit diagram here:
        http://mjlorton.com/forum/index.php?t…

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        DIY Bench Power Supply #8 – Mounting Transistors on the Heatsink
        8. Mounting Transistors on the Heatsink

        In this video I go through the process of mounting the 2N3055 (TO-3) and the BD140 (TO-126) transistors to a heatsink. This is in preparation for testing the power supply under load.

        Some parts for this project from my Amazon Store:
        http://astore.amazon.com/m0711-20?nod…

        * How to mount transistors to a heatsink.

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        DIY Bench Power Supply #9 – Transistors under load and adjustment with Pots
        9. Transistors under load and adjustment with Pots

        In this video I test the newly mounted power transistors on the heatsink. I show what kind of adjustment you can have with various potentiometers.

        The circuit does have an issue with oscillations which I will cover in the next PSU video.

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        DIY Bench Power Supply #10 – Heat Transfer between Transistor and Heatsink / Thermal Resistance Pt1
        10. Heat Transfer between Transistor and Heatsink / Thermal Resistance Pt1

        In this video I examine the various materials used to transfer heat from a TO-3 power transistor (2N3055) to the heatsink and how their thermal resistance can affect this.

        Materials used:
        * Adhesive mica and heatsink compound / paste
        * Heatsink compound only
        * Metal to metal with no insulating / thermal transfer material
        * Mica TO-3 washer only
        * TO-3 silicone washer only
        * TO-3 silicone washer and heatsink compound
        * Active cooling with a fan

        Then a stress test of the 2N3055 Transistor…with and without cooling

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        DIY Bench Power Supply #11 – Heat Transfer between Transistor and Heatsink / Thermal Resistance Pt2
        11. Heat Transfer between Transistor and Heatsink / Thermal Resistance Pt2

        In this video I examine the various materials used to transfer heat from a TO-3 power transistor (2N3055) to the heatsink and how their thermal resistance can affect this.

        Materials used:
        * Adhesive mica and heatsink compound / paste
        * Heatsink compound only
        * Metal to metal with no insulating / thermal transfer material
        * Mica TO-3 washer only
        * TO-3 silicone washer only
        * TO-3 silicone washer and heatsink compound
        * Active cooling with a fan

        Then a stress test of the 2N3055 Transistor…with and without cooling

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        DIY Bench Power Supply #12 – Heat Transfer Follow-up
        12. Heat Transfer Follow-up

        This is a follow-up to the “Heat Transfer between Transistor and Heatsink / Thermal Resistance” video. I demonstrate and use the Extech GX900 multimeter which helped me remotely monitor the status of the tests via Bluetooth.

        http://www.extech.com/instruments/pro…

        Buy the GX900 here: http://astore.amazon.com/m0711-20/det…

        I was asked to test a mica TO-3 washer and heatsink compound. I was also asked to test active cooling with a fan both drawing air away from the power transistor and blowing air directly on it.

        Thanks to Chris of http://www.analysir.com/blog/ for the Bourns 10K multi-turn pots: http://www.bourns.com/ProductLine.asp…

        http://www.alliedelec.com/search/resu…

        http://www.digikey.com/product-search…

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        DIY Bench Power Supply #13 – Breadboard to protoboard and troubleshooting
        13. Breadboard to protoboard and troubleshooting

        I decided to move the power supply circuit from the breadboard to a prototyping strip board. This will help with trouble shooting feedback loop stability (oscillations) that I have. Feedback loop stability will be covered in the next few videos as it is a very important topic related to power supply design. (Stability of Op Amp Circuits)

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        DIY Bench Power Supply #14 – Op Amp Stability / Gain and phase margin
        14. Op Amp Stability / Gain and phase margin

        In this video I use an analogy to help explain the issues with control systems that use feedback loops. Parasitic capacitance, inductance and resistance can lead to unstable / oscillating systems and circuits.

        Designers need to use Bode plots to understand the gain and phase margin in their designs required to operate in a stable mode.

  • Bench_Power_Supply-768x619A self contained Bench Power Supply has a power cord, case and a method of output connection. These tools can be heavy and large or like this one can be smaller and transportable. This handy tool is something that you may use to daily power up equipment or while testing circuits.

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