Introduction: DIY Variable Bench Adjustable Power Supply "Minghe D3806" 0-38V 0-6A

About: I mainly take on projects I have seen here and put my own twist on them. I also like to take garbage or thrown out electronics and make something nice from them. I have no certain area of Expertise, I am new a…

One of the easiest ways to build a simple Bench Power supply is to use a Buck-Boost Converter. In this Instructable and Video I started out with an LTC3780. But after testing I found the LM338 it had in it was defective. Luckily I had a few different Buck-Boost Converters and I ended up using a Minhe D3806. Even though this looks a little complicated it is actually pretty basic wiring. The Power supply saved me money on the build as I found a 19V 9.5Amp one at the local Goodwill for 5$. Here are the steps I took to through this together.

This build wouldn't have been possible without the partnership of JLCPCB. One of the cheapest Largest Manufacturers in China! Get your 2$ PCB at JLCPCB here-

This is actually one of the cheapest supplies I have made as you can find the parts used very cheap in China or a little extra from Amazon. Most of the stuff I had on hand and the cost will add up if you don't have most of the parts already. I tried to add everything I used in the Supplies. Links are direct and I get no kickbacks from them. I hope you enjoy this Instructable and don't forget to watch like and share the Video.


Minghe D3806-

LTC3780(Not used)-

Momentary Push Button Switch, Mini Push Button Switch No Lock Round 16mm 3A 250V AC/6A 125V AC Red Cap-

Electronic Enclosures Metal Shell DIY Project Junction Box Case Enclosure Preventive Case 250mm x 190mm x 110mm-

7S 8Pin Female JST-XH Lipo Balance Wire Extension Lead Charger Plug Terminal Cable 26AWG 50cm 5Pcs-

5-Pack DC-099 5.5 mm x 2.1mm 30V 10A DC Power Jack Socket,Threaded Female Panel Mount Connector Adapter-

10 Pcs Audio Terminal Connector 4mm Banana Jack Mount-

Pack of 10 AC 15A 125V Black Electrical Panel Mounted Screw Cap Fuse Holder-

LM2596 Buck Converter, DC to DC 3.0-40V to 1.5-35V Step Down Power Supply High Efficiency Voltage Regulator Module-

10K Ohm Knurled Shaft Linear Rotary Taper Potentiometer-

15amp Ac Switch Purchased at the local hardware store, but here is one that will work-

15 Pcs AC 6A/250V 10A/125V 2 Solder Lug SPST On/Off Mini Boat Rocker Switch Car Auto Boat Round Rocker 2 Pin Toggle SPST Switch Snap-

Mis wire and others already had on hand.

Step 1: Unbox & Inspect All Parts & Pieces

Before I start any project, I like to make sure I have all parts and piece available even if I don't use. During my inspection of the parts and pieces, I found the original Buck-Boost converter I plan to use was defective. Luckily I had a much stronger Buck-Boost Converter and decided the look would be much better. This Buck-Boost converter just meant I no longer needed the volt/amp meter or the Potentiometer. I just needed to find a way to mount the control board on the Minghe D3806.

Step 2: Tested the PSU & Minghe D3806

Before building, I like to test the Main Components. That how I found the defective Buck-Boost Converter (LTC3780). With this test of the Minghe D3806, I add a fuse just to protect it from Inrush current. Connecting the 19V PSU and turning on the power, reviewed the D3806 works Great. I made sure to test it at the lowest voltage and amperage, as well as the Highest Voltage and amperage. Made sure to double-check everything with a multimeter.

Step 3: Dry Fit & Check for Clearance

I wasn't sure how I would place all parts and pieces, as the main parts would be the Fan, Power Supply and Buck-Boost Converter. I took them all and put them in place. Looks like I will have plenty of room and I only need to figure out how to mount them in place later. I'm starting to see the layout of the face now also, as I will need to figure out how to extend the control board. The Control board is probably the most important part of the build.

Step 4: Make Extensions for the Control Panel (D3806)

Pulling off the control panel revealed I would need something with 8 pins. I had some extra 7S Balance wires from a previous build that would work perfectly. All I would need is to cut them to fit and add Pins to the bottom of the wires. Luckily I had some of those from a previous build. After I solder the pins, I add silicon to help hold them in place. Balance cables will work Perfect.

Step 5: Prep the 19V 9.5 Amp Power Supply

To keep the Power supply Cool, I decided it would stay cooler out of the plastic housing. After removing the 4 screws the housing came right off. I also cut and prepped the wiring. For some reason, one of the wires had no insulation, so I added heat shrink to be safe. After I prepped, I made sure to check the voltage.

Step 6: Prep the Smaller Fan Buck Converter

On most of my Projects when I have a fan. I like to control the fan speed with a Buck converter. With this fan, I will be using an lm2596. So I simply desolder the Potentiometer and added an extension using a bigger 10K Potentiometer. This will be the first time I added a Potentiometer, so I can control it easily with a knob. I also did some testing to make sure everything works.

Step 7: Unbox Case & Add Masking Tape to Face

Taking all the plastic off the case, revealed the case has a face that is screwed on with screws and plastic housing that takes up some of the face space. So I used a marker and marked the inside, so I knew where I could place all the parts and pieces. I also add Masking tape to the face. I always use masking tape, just encase I mess up and need to replace it with new tape. I need to figure out where everything will go along with the Control board.

Step 8: Mark & Drill Holes for the Front Panel

Taking my time, I made sure to mark the center of the face. I did this so I could figure out how to add the Control panel, Buttons, Power switch, Saftey switch, and all the Banana Jacks. After I find and mark where everything will go, I write the size to drill. I Also drill the corners of my square cutouts. Using a Dremel, I cut out the panel section and after the safety switch. Each hole cut Out, I start with a small drill bit and work my way up to 1/8 inch bit. Then I take a step bit and drill out the rest of the way. I use masking tape on the step bit, so I don't go too deep. I also use a square-file to help make the square cut out straight. I also like to double-check and make sure everything fits. After the step bit, I clean up all brought areas with a round-file.

Step 9: Mark & Drill Holes for Back Panel

The back only needs 3 holes. One for the Potentiometer going to the fan. One for the DC In, so I can use batteries if need be, to power the Bench supply without ac. The last hole is for the AC cord. Like the face, I used masking tape, marked the holes and a step bit to make the correct size.

Step 10: Add Black Vinyl Wrap to Face (Back,Front and Top)

One of my most favorite thing to add to my project is Black Vyle wrap. So in keeping up with tradition, I add the black vinyl wrap to the face and back panels, and not show is the top section. I used an X-Acto blade to cut the holes and edges. If I have any small Bubbles I can not get out, I simply cut a small slit and push it out with my finger.

Step 11: Prep Case for the Power Supply

I wasn't sure how I planned to keep everything stationary. But later decided I could just use Zipties. So I marked where I plan to put the Power supply with a marker. Than marked 4 holes, where I could use Zip Ties later.

Step 12: Prep the Control Board

To keep the control board from pushing the buttons it already had. I add 2 small prices of wood from old chopsticks. I used Silicon to hold them in place. To control the board, I plan to use the bigger Mometary buttons on the panel. So I soldered 2 wires to each button. I will later solder the wires directly to the Buttons of the face. I also added silicon to the wiring to hold them in place. To make sure I soldered correctly I double-checked with a multimeter.

Step 13: Solder & Add Components to Face

Now is the time to start adding all the Components to the face part of the build. Because I plan to add a banana jack for charging along with the Positive. I added a 15amp 45V Blocking diode. This will protect the Converter from any back feed energy coming from the battery when I plug it in. I also added an extra switch, that I connected to the black Banana jack. This will protect anything I am working on from out rush energy coming from the converter. This converter is known to do that. Or I have seen this mentioned in other videos. I also made sure to mark the buttons on top of the control panel. So when I solder to the buttons, I put them in the same place.

Step 14: Add Buck Converter to Fan

With silicon, I added the buck converter to the fan. I also took the bigger wires off and just soldered directly to the fan. I also tested with my bench supply to make sure it worked properly. I'll set this aside to dry for now.

Step 15: Solder the Main Wires That Go to the D3808 & Front Panel

The connections from the face are pretty simple. To the output of the Converter, I will need wiring running from the negative side, but through the switch. That way it protects whatever I have connected. The red or positive just goes connected directly to the banana jack. The wires from the Fuse will get connected between the Positive. I will use a 9 amp fuse to protect the D3806.

Step 16: Finish PSU Adding Diode & AC Wires

I added wires coming from the back of the Power supply, by color. This is just to extend the connection and make it easier to solder later. I also added a blocking diode to the output of the Power supply. This will protect the Power supply if I later decide to use the DC jack. The DC jack in the back is for plugging in a battery later. I always like to add a battery power into my DIY Power supplies. This just gives me the option to use a different power source or to make it portable.

Step 17: Add PSU, Fan & D3806 to Case

Using the holes I drilled earlier, I added zip ties to the Power supply and snugged up. This should hold pretty good. The D3806, I drilled four holes in a small piece of plexiglass and added. I glued it with superglue and silicon to the top of the power supply and on top of the zip ties. I also superglued and used silicon to glue the fan in place. Once everything Dries I can add the back and front panels.

Step 18: Solder AC & Add Back Panel

I placed the ac wire through the hole in the back panel and used zip ties and silicon to hold in place. Then I soldered it to the Power supply, using shrink tubes to isolate. The DC jack from the back, I added to the power supply by polarity and screwed into the plastic block terminals. I also added the positive and negative from the Fan buck converter. Last I screwed the back face to the case and added the 10K Potintomter from the fan. I also connected the negative from the Powersupply, back DC jack, and fan converter to the D3806.

Step 19: Add Face & Connect Wiring

I screwed on the face. The Positive from the banana jack gets connected to the output of the D3806. The negative from the switch gets connected to the output of the D3806. The Wires coming from the fuse gets connected to the positive from the power supply and DC jack. The other wire left over from the fuse gets connected directly to the D3806 input. Using the 7S Balance cables I made earlier. I connected them to the back of the control panel and the pins to the D3806. Make sure to connect the exact way it was connected before extending with the 7S cables.

Step 20: Add Top Panel & Test

Only 4 screws and the Top was added. I then connected to AC and Powered it up. Testing all the Monetary Buttons, showed the Control panels is connected and working perfectly. Turning the power on, and the Switch I added for protection work great. Blocking diode to the Battery Banana jack is working also. I decided to do a little test and connected to my portable Battery Charging and discharging station. You can find that build on my Youtube channel. Later I also testing by charging a 5S battery. Constant Current, Constant Voltage works great.

Step 21: Thanks for Watching and Reading the Instructable

Very Easy to Build and I plan to use this a lot in the next few days. I am very pleased with the way it turned out and happy I need up using the Minghe D3806 over the other Buck-Boost. I prefer the buttons over the Potemtiomter look. I am also pleased with the battery charging output. I also used a green banana jack, only because I had one on hand. I wish I could have found maybe a white or blue one. But for now, the green will have to do. (green usually means AC Ground). Other than that, It works Great!!!

Thanks again JLCpcb!!!$2 For 5 PCBs & Cheap SMT(2 Coupons):

njfulwider5(Tons of Awesome DIY Projects)-

I really appreciate you guys reading and watching my instructable. Make sure to watch the video also!! Don't forget to Subscribe and Share!! Thank you all!!!!