Playlist Content

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  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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  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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  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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  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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  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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  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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  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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  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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  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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  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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  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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  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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  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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  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.