My new project was inspired by programmable power supply, module Ruideng. It is fantastic, very powerful, precise and for reasonable price. There are few models available, concerning output voltage and current. The newest ones are equipped with communication options (USB and Bluetooth).

Programmable - variable Power Supply described in this article, is dedicated for DIY electronic bench. It was originally based on Ruideng model DPS 5015 without communication. During writing my Instructable, modules with communication were introduced to the market. I have added this option as version B.

Parameters:

AC input: 100 - 220V
AC frequency: 50Hz/60Hz
DC voltage output: 0 - 42V
DC current output: 0 - min. 4A, max 5A (DPS5005) or 6A (DPS5015)
Output voltage resolution: 0.01V
Output current resolution: 0.01A, (0.001A for DPS5005)
Output power: 200W
Output voltage accuracy: +/-(0.5% +1 digit)
Output current accuracy: +/-(0.5% +2 digits)
Number of memories: 9 sets of data groups plus the last setting (memory 0)

What means Programmable?

Power supply Ruideng DPS 5015 or DPS 5005. You can adjust parameters of the power supply and save them to its memory internally, from the front panel. You can not adjust and program any parameters externally. There is not any connector and any link to program parameters from outside. Version A.
Power supply Ruideng DPS 5005 communication version. These Ruideng module allows communication from the outside of instrument via USB micro connector or Bluetooth. You can adjust and program all parameters from PC. Version B.

Main programmable parameters are:

Voltage
Current
Over-(voltage, current and power)

Tools:

Small jig saw
Drill
Soldering iron
Multimeter

Step 1: Parts

In my case, main part is programmable power supply Ruideng DPS5015. This module contain colour LCD, which displays all necessary data. DPS5015 was available for low price. The module could provide maximum DC output 50V and current 15A. Current value DPS 5015 is not fully exploited here, but I have purchased it, in temporary discount for less than 20€. The best solution for this case, there is model DPS5005, communication version, I recommanded it.

Any DPS module Ruideng require on its input some other power supply, (switching or not switching) with ability to deliver about 50V and 5A or more. Such power supply could be made on main transformer 220V/50V and some other components. This solution is very heavy and big size and not very efficient. Switching power supply is more economical. Therefore I decided for switching power supply, to change 220V AC to 48V DC. I could not find suitable one, so I have used two modules 220VDC/24VAC. Modules are connected in parallel on theirs inputs and in serial on outputs.

Parts are:

Switching power supply Geekcreit 24V/4-6A, 2pcs, Banggood
A version, without communication, Programmable PS Ruideng DPS5005, (or DPS5015) Banggood
B communication version, Programmable PS Ruideng DPS5005 communication, DPS Banggood
Plastic instrument box, Banggood
Main power switch, Banggood
Fan 12V, as for instance ebay
Adapter 220VDC/12VDC, as for instance, ebay
Female bannana jack sockets, 2pcs, ebay
Thermistor, 10kohm, ebay
Driver for fan, built on small protoboard, Banggood
Power main cable 220V, 2.5A from local store, depends on the plug type.

Parts in driver for fan:

Transistor 2N5401or BC337, Banggood
Diode universal 1N4148, Banggood
Trimmer resistor 1kohm, Banggood
JST female connector 2.5mm on board, 3pcs, Banggood
JST male connector 2.5mm with cable, 3pcs, Banggood

Step 2: Wiring Diagram - Version a - No Communication

Connections between all blocks is drown on picture above. On the left side, there is input 220V, main cable and main switch. On the middle there are two modules AC/DC 220V/24V. These modules are connected in parallel on input, voltage AC 220V. Both module are connected on their outputs in series and attached to the input of programmable PS. Each module deliver 24V DC, so total output voltage is 48V. Programmable PS DPS 5015 is attached to output connectors (plus and minus of the instruments output voltage) and by ribbon cables to LCD display. On the picture in upper part is adapter 220V/12V, fan driver and the fan 12V. There is not displayed thermistor on the picture. Thermistor with negative temperature coefficient, NTC is mount inside one of aluminium cooler.

Programmable DPS 5005, following drawing, contains all electronic circuitry located inside display part. You have more space in plastic box. Wires are connected directly from switching power supplies to display and from display to banana connectors.

Scheme for hardware of fan driver is on next picture. Connection is very simple, just few components. Transistor T1 switch on the fan according value of thermistor. If thermistor is exposed to higher temperature, his resistor value is decreased and transistor conduct more current, fan is running. Diode D1 protect transistor.

Generally, there is not necessary cooling fan for all modules. Programming PS 5015 is equipped with its own small fan. DPS5005 does not need any cooling. Both switching modules require cooling in case of higher power output. Therefore, I have provided block of two switching modules with fan. Fan is switched on, just in case of higher temperature of aluminium cooler on one of two module boards.The most operating time is programmable power supply quiet.

Special adapter 220V/12V deliver voltage 12V for fan. I choose this solution, because I prefer separate power supply for fan.

Step 3: Wiring Diagram - Version B Communication

Wiring diagram is the same like version A, module Ruideng DPS5005, just USB communication board is added. It is on picture above. USB board is connected by its original cable with connectors on both sides.

If you order Ruideng communication model with two communication boards, USB and Bluetooth, you can connect just one board in time, because the display module contains one connector only.

There could be solution for both boards, but I did not check functionality of next described circuit. Mount on free space of plastic bottom box both modules. I suggest connect as priority board - Bluetooth and USB is connected just in case of connected USB cable. Wires could be fed through 12V relay 4PST, or through two relays DPST. Independent 12V DC voltage is available at adapter output. Place micro switch in place, where USB connector is inserted, such a way, that inserted connector activate switch. By switch could be energized relay and switch wires to USB board.

Four wires coming to communication boards supposed to be: VCC, GND, TX, RX. If you able to identify VCC and GND, just remaining two wires should be switched by one relay DPST. Both boards could be connected to power permanently if instrument is switched on.

Step 4: Construction

Construction steps, version A

Power supply is placed to the ready made plastic instrument box. This save time and simplify construction. Next steps are for DPS5015. In case of DPS5005 in step 3. just mount voltage adapter and you get some free space on bottom part of plastic box::

Prepare plastic box: remove same plastic mounting feet from bottom part of box, (marked by circle with black pen). Drill holes and cut windows in plastic front panel and back panel according to above pictures.
Mount both switching PS and fan together in one assembly. Use metal right angle joints and screws. Mount this assembly to bottom plastic case using mentioned joints and screws. Do not forgot to attach wires to terminals, because later it is not possible or not so easy. On wires going to programmable module solder fork connectors.
Mount programmable PS 5015 module and adapter to bottom plastic case using joints and screws. Prepare wires for output connectors and solder on them fork terminals. On adapter output solder two wires with JST connector to fan driver and two input wires to screw terminal 220V.
Solder parts of fan driver on small print circuit board or protoboard. Size of this board is about 15 x 25 mm. Cut connector wires to proper length and solder them to fan, thermistor and adapter output 12V.
Place and fix thermistor on one of aluminium cooler. I fix it by inserting thermistor inside hole of heat sink.
Mount parts on front panel. Power switch, two banana connectors and LCD display.
Place front and back panel and connect all wires.

Construction, version B.

Mount USB communication board on free space of plastic bottom part such a way, that connector is faced to the right. On the USB board, there are two holes and using standoff, screw board to plastic box. Cut a hole for connector on side of the box.

Front panel

On the last picture,there is front panel. You can use it as template. Drawing was made in Paint program in Windows 10. You can modify design very easy. Drawing is done exactly in the size of front panel (scale in mm). By printing there is necessary to choose print size 100%. To make it nice, choose photo paper and protect it by transparent adhesive foil.

Adjustment

There is a good practice to check all modules and parts in the process of mounting. I recommand to check fan driver connected to fan and attached to 12V at first from some other power supply. Fan should run or not run depending on trimmer position. Somewhere in the middle of trimmer trace fan just stop. If you place thermistor to some hot place (like solder iron), fan should start rotate.

By next check both switching power supplies. Connect 220V from screw terminal to their inputs and connect their output to serial. You should measure the final voltage 48V. Both modules should be equal concerning output voltage and current. If you can choose them, take two with the output voltage exactly the same. In this case power supplies are well balanced.

If voltage 48V is correct, connect programmable PS. Be careful, do not mix input and output, and plus and minus on input, programmable module can be destroyed.

At the end connect driver board for fan and all remaining cables. Cables drawn like thick on wiring diagram should be thicker, because of higher current. On input 220V, wires diameter should be about 1mm (max. current 2A), on output 48V should be diameter 1.5mm (max current 6A).

Step 5: Communication

Visit site with link communication software and download DPS5005 PC software for communication. Detailed information, how to install software and how to use it, how to configure serial port for USB, how to configure Bluetooth, is on video: communication .

On PC software, functions in Basic tab (the first picture) are very similar to settings on non communication version. On Advanced tab (the second picture) are more sophisticated functions which could be used for automatic component measurements. Except more clear and simplified memories for data groups there are functions:

Auto test - allows to adjust number of steps (maximum 10), time intervals by delay value for each step, voltage and current for each step.
Voltage scan -allows to adjust output current, start stop and step value of voltage, one delay common for each step.
Current - scan. Function the same like voltage scan. Adjustment of output voltage, start stop and step value of current, one delay common for each step.

Step 6: Conclusion

User manual for Programmable PS Ruideng is including in shipment. Just a few comments:

Very good feature is possibility to connect or to disconnect load on output connectors by switch. That way during voltage and current adjustment should be load switched off and protected.

On above pictures, there are example of constant current mode. On top line of LCD are displayed set voltage and current. On output connectors is connected resistor 4.7 ohm. Although voltage is set to 10V, voltage on output is about 4.7V, because current is set to 1A and was achieved.

On the next picture there is Zener diode attached to output without resistor. Current is set to value about 0.05A and voltage line is showing directly Zener voltage 4.28V. By such component measurements there is important to check displayed power on the third big line (0.25W in example). I have destroyed a Zener diode for 30V, because adjusting 0.05A, I had missed power over 1.5W!

In 9 memory places could be stored very often used voltages, like 3.3V, 5V, 6V, 9V, 12V and so on, with its expected currents, over voltages and over currents.

Communication version allows some automation for component testing. It is like measurement of voltage to ampere characteristics or some battery charging with time and current depending voltage.

Comment about front panel. There was too big space on the left side of LCD display. I was thinking to put there something crazy, like LCD thermometer for inside temperature or sedentary reminder, but finally I decided for picture, because of using photo paper as front cover. Between nice nature (mountains) and the most beautiful city, win the city.

Hope you will enjoy doing the nice power supply yourself.