Variable Bench Power Supply DC 1.2-24V 8A(MAX) 120watts !!

Hello There ! In this Instructable you will be getting a idea of how I build my own lab bench power supply. This power supply has a Ac to Dc convertor, step down converter (Buck converter), temperature controller and Display to show voltage and current . This bench power supply can supply 1.2v-24.6 v DC as per the requirement you can adjust the potentiometer and take the output.

Step 1: Parts List

1) Power Cable

2) Power Socket

3) Fuse (or you can buy from nearest electronic shop) x1

4) Fuse Holder x1

5) DC to DC Buck Convertor for Temperature Controller

6) Temperature Controller

7) AC to DC power Converter (24v)

8) Voltage and current regulator (1.2 - 24v)

9) Precision Potentiometer 10k OHM X2

10) Potentiometer Knobs X2 (or you can find knobs from nearest electronics store)

11) Voltage and Amperage Monitor (10A)

12) Banana Socket

13) Banana Connector

14) 12v DC Cooling Fan (You can even buy bigger size than this fan that is upto you and according to your box size)

15) Box Enclosure (According to your choice)( but it should be of minimum of 23 x 14.4 x 5 cm size

16) Crocodile Clips

Step 2: Step :AC 110/220V Input

CAUTION!!! 220v AC Supply Be aware and if you are not aware and not having any Knowledge in electronics or electrical subjects then prefer to buy readymade bench supply.

The Power Socket has a 3 in one Function : It has a input socket ,fuse and a switch. If we connect any electrical appliance, which consumes more than 10 amperes this helps in protecting the circuit from being destroyed. This Power Socket arrangement makes the project to look clean. Make connection according to the above pictures.

Step 3: Voltage and Current Regulator

This is 300W 10A DC-DC Step-down Buck Converter Adjustable Constant Voltage Module can be used to get adjustable output voltage ranges from 1.5V to 35V. The module provides a wide range of current output up to 10 A. With heat sink mounted it can easily manage to run high power application continuously (provided that for continuous high power output you need to use a cooling fan on the heat sink).

The module has onboard 3296 multiturn potentiometers for high accuracy voltage and current regulation to provide good stability. As voltage and current are adjustable, it gives very easy to use at multiple Application such as battery charging, LED Driver power supply, Vehicle Power Supply, etc. Which makes the module Multipurpose and hence this module is always in demand from our maker because of its wide range of application and low cost. In the next step we have to take those potentiometers out and replace them with precision potentiometer.

Step 4: Connecting Precision Potentiometers

I'm using 10k precision potentiometer here as precision potentiometer can adjust the output whether its voltage or current it can be done easily as it provides with fine adjustment. As the schematic make connection with xl4016 module just by removing the 3296 potentiometer that is usually come fixed onto the xl4016 buck converter. The main task is to remove those using soldering iron and then connecting 3590 precision potentiometer using good quality ribbon wires. Do make sure connection must be same as given in schematic diagram.

Step 5: AC to DC Converter (85-220v AC - 24 V DC)

This is AC to DC power Converter. It can handle a Input AC from 85 to 265V and gives a constant Output as DC 24V. Maximum load is about 4 -6 Amp according to your load. That is : 24 * 4 ≈ 100W. The Power Converter has an overload protection and short circuit protection. It is Just that from step 2 the two wires of + and - 220v AC is directly given into the AC input connector (Green connector )and 24v DC is output from other side (Blue connector).

Step 6: Schematic

In this schematic as you can see that there is individually connected input socket, fuse and switch. But instead you can buy the socket given in part list. It is recommended that you buy the socket as it is easy to connect after all the connection as of step 2 after that two wires of both positive and negative is given directly into the power supply unit.

There is output fuse in this circuit diagram which protects from any short circuit at the output. This is an optional part if you want more protection you can add the fuse at the output side otherwise its not necessary as the xl4016 itself has a short circuit protection.

Step 7: Cooling System Connection

As per the circuit diagram make connections. This cooling system helps the modules to keep cool and can be used for long term usage under nos. of loads .Before giving the supply into temperature controller check the output voltage from mini buck convertor and the set it to 12v and then give into temperature controller.

Step 8: Cooling System

W1209 thermostat module has a temperature sensor, keys, LED display, relay and requires DC 12V power supply. It is an affordable, good quality thermostat controller. Thermostats are devices that sense the temperature of a system so that the temperature is maintained at the desired set point or near to it. NTC temperature sensor allows the module to intelligently control varied electrical devices based on the temperature. NTC thermistor has a negative temperature coefficient, which means the resistance decreases with increasing temperature. W1209 has an inbuilt embedded micro-controller, thus not much programming knowledge is required. The module consists of three switches to configure the various parameters including ON and OFF trigger temperatures.

The temperature is displayed in degree centigrade and with the help of 7-segment display and the relay, the state is displayed with the help of the LED present on the W1209 module.

Settings Chart:-

Long press the “SET” button to activate the menu.
Code Description Range Default Value--------- Keep the value on 36 (by pressing + button /increment or press - button/decrement to set the value).
P0 Heat (C/H) --------- Set it to C
P1 Backlash Set (0.1-15)----------------- Set it to 4
P2 Upper Limit 110------------------ No change
P3 Lower Limit -50 -------------------No change
P4 Correction (-7.0 ~ 7.0)----------------- Set to 0
P5 Delay Start Time (0-10 mins) ---------Set to 0
P6 High-Temperature Alarm (0-110) -------Set to OFF
Long pressing +- will reset all values to their default.

Step 9: Digital Voltmeter (0-100V) and Ammeter (10 A)

This is the digital display onto which we can see the output voltage and current by adjusting the potentiometer being apply to the load .Make the wire connection as in schematic diagram the thin yellow (voltage sense) wire is given directly into the xl4016 out+ screw terminal .The thin red and black is given directly into the 24 v DC outlet + and - of the power supply unit. The thick black wire is given into out - of the xl4016 and the thick red wire is given to the out banana plug socket or connector.