Adding a Current Limit Feature to a Buck/Boost Converter

In this project we will have a closer look at a common buck/boost converter and create a small, additional circuit that adds a current limit feature to it. With it, the buck/boost converter can be used just like a variable lab bench power supply. Let's get started!

Step 1: Watch the Video!

The video gives you all information you need to recreate the circuit. In the next steps though, I will present you some additional information.

Step 2: Order Your Components!

Here you can find a parts list with example seller (affiliate links):

Aliexpress:

1x Buck/Boost Converter: https://s.click.aliexpress.com/e/_dTevK0K

1x LF33 Voltage Regulator: https://s.click.aliexpress.com/e/_dT0fKCw

1x 10nF Capacitor: https://s.click.aliexpress.com/e/_dU4FEsB

1x 10µF Capacitor: https://s.click.aliexpress.com/e/_d7dOwRz

1x 0.1Ω Current shunt: https://s.click.aliexpress.com/e/_dSyQdMA

2x 3.3kΩ, 2x 100kΩ Resistor: https://s.click.aliexpress.com/e/_dTPpXjt

1x MCP602 OpAmp: https://s.click.aliexpress.com/e/_dTvJRGw

1x 10kΩ Trimmer: https://s.click.aliexpress.com/e/_dTFyPv5

1x UF4007 Diode: https://s.click.aliexpress.com/e/_dYR45Bh

1x Voltage/Current Meter: https://s.click.aliexpress.com/e/_d8lymHM

Ebay:

1x Buck/Boost Converter: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x LF33 Voltage Regulator: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 10nF Capacitor: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 10µF Capacitor: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 0.1Ω Current shunt: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x 3.3kΩ, 2x 100kΩ Resistor: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x MCP602 OpAmp: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 10kΩ Trimmer: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x UF4007 Diode: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x Voltage/Current Meter: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

Amazon.de:

1x Buck/Boost Converter: http://amzn.to/2w1WgTz

1x LF33 Voltage Regulator: http://amzn.to/2w1f2dF

1x 10nF Capacitor: http://amzn.to/2xIowip

1x 10µF Capacitor: http://amzn.to/2habIql

1x 0.1Ω Current shunt: http://amzn.to/2haAOWd

2x 3.3kΩ, 2x 100kΩ Resistor: http://amzn.to/2w2jSaI

1x MCP602 OpAmp: http://amzn.to/2x61uBr

1x 10kΩ Trimmer: http://amzn.to/2x9NmVc

1x UF4007 Diode: http://amzn.to/2w2vzxU

1x Voltage/Current Meter: http://amzn.to/2xJ2YCt

Step 3: Create the Circuit!

Here you can find the schematic and pictures of my completed circuit. Use it as a reference to create your own.

A rather tricky part is the current path on the output side of the converter. If you want to hook up the current shunt and the V/I meter then your wiring should be like this: Out+ -->Load+ -->Load- --> Red Wire I Meter --> Black Wire I Meter --> Current Shunt 1 --> Current Shunt 2 --> Out-