However, it is impractical to vary the voltages for different devices. First, the input jack is located at the bottom of the case, which unfortunately creates an uncomfortable angle for holding the screwdriver when adjusting the voltage and leaves little room for your fingers. Second, a multimeter is needed each time to measure the voltage. The goal of the adjustments was to improve the handling and the design.

This might also be interesting for you: Development of a charging device from a LM2587S Step-Up 

Liste der Bauteile:

• 1x hollow plug 5.5 x 2.1
• 1x screw socket 5.5 x 2.1
• 2x flat head screw M2x6
• 2x flat head screw M2x4
• 4x raised countersunk head screw M2x10
• 1x Module LM2587S DC-DC Step Up
• 2x Pico fuse 3A 125V / 230V
• 1x Mini Voltmeter Digital with LED display 0,36″ (optional)

Housing construction of the LM2587S voltage converter

The vertical position of the socket results from the housing length. Since the power input is now to be on the back, the housing had to be longer. 12 mm was sufficient to install the socket horizontally. Due to the length of the housing, the screwdriver can easily fasten the socket on the inside.

Alternatively, the socket could have been rotated 90°, which would have kept the socket on the side and the length of the housing the same. However, the distance to the opposite wall would be extremely small and problems would arise when screwing. You would need an angled screwdriver or drill mounting holes in the side panel.

Now the bridge bushings had to be modified. Otherwise the bridge would collide with the corner at the ends. The interfering parts on the bridge were removed in CAD. The column height remains the same, since the bottom thickness and the back wall thickness are the same. The lid also had to be adapted to the length and given a cutout or socket for the mini voltmeter.

The voltmeter 3631AS-1

When selecting the mini voltmeter, I chose the “3631AS-1” variant. This voltmeter sits on a circuit board that has tabs with holes so that you can screw it to the housing cover. On this voltmeter the cables are already soldered with the correct colors (red for plus and black for minus). To protect the voltmeter from mechanical damage, I added a frame to the case lid.

The case height does not have to be changed for the LM2587S voltage converter, because there was already enough space in the previous version. The work on the CAD is definitely an advantage here, because the lid can be extended easily without a cutout for the voltmeter and you get a variant “long” for those who do not need a voltmeter, but want to have the input at the back.

As always, the components were produced on the 3D printer and afterwards the thread was cut (in this case M2). Soldering is very simple, like with the predecessor, and the two additional cables from the voltmeter are screwed to the OUT cables on the hollow connector according to the color.

Setting and adjustment of the LM2578S voltage converter

Now to the adjustment of the LM2587S voltage transformer. Here was mainly the accuracy of the voltmeter interesting. Generally the adjustment should be done under load. That means with a connected load (e.g. a resistor). I repeated the measurements several times and was amazed about the accuracy of the mini voltmeter.

The maximum deviation was less than 0.04 V and this even with different input voltages. The device has been extensively tested from 4 V to 32 V. I recommend not using more than 30V output voltage for operation during longer operation, because the voltmeter is not suitable for higher voltages on a long-term basis.

Of course, the contact resistance is important, because each additional connector reduces the voltage. Therefore follows:

• Avoid unnecessary plug connections
• Always measure voltage at the last connection

Safety aspect

The safety should not be forgotten either, since the step-up in contrast to the step-down has an open circuit, it should be provided with a fuse! At my step-up I have subsequently attached (unfortunately not visible in the photos) a lazy pico fuse with 3A at the positive terminal on both the input voltage and the output voltage. Thus, you can start using it!

Download files:

• STL files for 3D printing (with voltmeter)
• STL files for 3D printing (long version without voltmeter)

The post Improved LM2587S voltage converter (Step-Up Modul DC-DC) appeared first on Nerd Corner.

This might also be interesting for you: Step-up module DC-DC LM2587S

List of components:

• 1 x hollow plug 5.5 x 2.1
• 1 x screw socket 5.5 x 2.1
• 2 x flat head screw M2x6
• 4 x raised countersunk head screw M2x10
• 1 x module LM2596S DC-DC Step Down

Implementation of the LM2596S step-down

For the step down converter, the DSN2596 was chosen because the module is cheap and widely used. To develop such a switching regulator by ourselves would take a disproportionate amount of time and money. Furthermore, the DSN2596 costs only a fraction of the price of the individual parts that would be needed for a self-developed switching regulator.

But be careful, some dealers sell DSN2596 modules that do not keep what they promise. It is important that the switching frequency of the LM2596 must not be below 150kHz. If you have an oscilloscope you can measure the ripple voltage at pin-2. The input voltage range is normally between 4 and 35 volts and the output voltage between 1.5 and 30 volts.

The output current is 2A without cooling and 3A with cooling. A heat sink should definitely be used and placed directly on the LM2596! For more than 2A output current, I prefer an XL4015, but this is rarely the case, as the 2A is usually sufficient. As always, the input voltage should be at least 1 Volt higher than the output voltage!

The efficiency of the module depends mainly on the difference between input voltage and output voltage. This means the higher the difference the more inefficient the module.

Construction of the case

The housing for the step-down module was developed analog to the housing of the LM2587S. The only differences are the mounting holes for the module and the position of the hole on the lid for adjusting the voltage via potentiometer. If you are interested in how such a case is constructed and what to consider, you can read more about it in the article about the LM2587S.

The following drawing shows how to assemble the case. It is not necessary to use the normal screws for this. The core holes for the M2 thread are also suitable for self-tapping screws. If you have an aversion to tapping or do not have an M2 tap available, you can also use other screws.

Download files

• STL files for the LM2596S
• STL files for the LM2596

The post Step-down Modul DC-DC LM2596S appeared first on Nerd Corner.

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List of components:

• Hollow plug 5.5 x 2.1 1 times
• Screw socket 5.5 x 2.1 1 times
• Flat head screw M2x6 2 times
• pan-head screw M2x10 4 times
• Module LM2587S DC-DC Step Up 1 time

Realization of the LM2587S step-up converter

A step-up module is needed. I decided to use a LM2587S DC-DC step-up module, because I already had it at home. Furthermore a plug for the socket at the battery and a socket for the power supply from the antique 24V power supply is needed. Plus some cable, screws and a case to protect the electronics.  All parts can be ordered easily, except for the case. This will be designed in CAD. For this, the parts that go into the housing must first be measured, since the official documentation and drawings of the parts are often faulty or not available at all!

Housing construction

When designing the housing, other questions arise such as:

• Should the housing be plugged directly to the battery or should there be a cable in between?
• Should the connector socket in the case or also be connected to the power supply through a cable?
• Do I need a fan (active) or are ventilation slots (passive) sufficient?
• Should I be able to adjust the voltage without opening the case?
• How big should the case be?
• Etc…

My solution was not to place any cables outside the case and not to use a fan. The size of my case should be about the same as a small powerbank with a 18650 battery. The circuit board should stand on columns inside the case. This has the advantage that the air can flow through better and the length of the thread is longer. By the way, an M2 thread should be sufficient because no large forces occur. The M2 thread is difficult to 3D print, so I cut it with a tap.

On the sides inside the case I left enough space for the cabling. In total only 4 cables are needed. For the socket that takes the plug from the power supply, I use a so-called bridge that stands on columns like the board. In this case the height of the bridge columns is the same as the columns of the PCB. With the bulges on the bridge I regulate constructively how far the socket stands in the housing.

The difficulty is to find the right center position, because the plugs are not all the same length. The lengths of the plugs differ partly up to 2mm! If you put the socket too deep into the housing, the holding mechanism of a short plug can’t grip and the cable including the plug slides out of the socket again. But if the socket is out of the housing, it can be damaged or scratch the surface on which the housing lies. In my experience, the socket should be recessed between 0.5 and 0.75mm in the housing. This is how I implemented it.

For the plug to the battery of my vacuum cleaner I use a standard rubberized screw plug. The challenge was to place this plug with guides in the housing and to press it down with the lid, so that the plug holds and does not wobble! I also planned threaded holes with M2 threads for the screw connection of the lid.

My three components were designed in CAD and then 3D printed. Soldering the electronic components is comparatively easy, because IN/OUT is already printed on the module. Unfortunately, I often confuse plus and minus on the socket, so I have included an illustration. Mostly here is outside minus and inside plus.

Measuring the voltage of the LM2587S step up

After successful assembly, the LM2587S boost converter is tested and adjusted to achieve the correct voltage (26V) for charging the battery. To measure, simply use a standard multimeter. The best way to adjust the measuring cables is to arrange the cables in a socket with glands. Then plug in the old power supply (23.5V output voltage) and turn the screw on the potentiometer counterclockwise through the hole with a small slotted screwdriver, always keeping an eye on the display. You have to turn the screw a few times to see the result on the display. When the desired voltage is reached, wait at least 15 minutes and readjust again. Mostly the voltage goes up by 0,3V-0,6V after a longer time. If nothing is hot but slightly warm and there is no unpleasant smell of burnt plastic, everything should be fine.

You can use this step-up module LM2587S for:

• Input voltage 3V-30V
• output voltage 4V-35V
• Output current max.5A

LM2587S step-up converter Remark:

• The output voltage should always be 1V higher than the input voltage.
• The input voltage should never be more than 30V
• The input current should be plenty higher than the output current

Download files

• STL files for the LM2587S step up

The post Step-up Modul DC-DC LM2587S appeared first on Nerd Corner.