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Exploring Buck and Boost Converters

White board sketch of 12 V Car Charger for USB Device. Image Description under Featured Image Description Heading
Learning Goals

  1. Students will use multimeters to measure voltage and current in circuits. 
  2. Students will use collected data and be able to make power calculations from this data. 
  3. Students will also be able to calculate efficiency from their power calculations. 
  4. Students will be able to compare efficiencies in order to identify the circuit that is most efficient. 
  5. Students will be able to make circuits from a diagram and vice versa.
Materials List

Group Supplies (2-4 Students)

  • Adjustable Boost Converters (see pics below) at least one per group (adjustable is optional) 
  • Adjustable Buck converters – at least one per group (adjustable is optional) 
  • AA battery holders – 2, 3, 4, 6 Batteries in series in (to modify input voltages) – 1 per group 
  • AA rechargeable batteries – 10-12 per group 
  • USB current/voltage meters 
  • Multimeters (2 per group – one for voltage and one for current) 
  • ATC fuse holders (used for measuring current) 1 per group (see pics below) 
  • Cell phone or device that uses a USB plug for  charging – students can bring in a USB charging cord for their phone, or instructor can supply any USB charging device. (I used LED bike taillights that charge with a USB.)       
  • USB female plug with leads attached – I used small 5 Volt solar panels with USB leads and a female plug attached – these panels cannot  directly charge most phones, so I cut the leads and used the USB female plug, and then use  the panels to recharge our battery packs. 
  • Male and female DC power plugs with pigtails (1 each per group)

Important Links

Next Generation Science Standards

Next Generation Science Standards

  • HS-PS3-1. Create a computational model to calculate the change in the energy of one  component in a system when the change in energy of the other component(s) and energy  flows in and out of the system are known.  
Featured Image Description

Drawn on a white board in red marker 12 V CAR CHARGER FOR USB DEVICE underneath is a circuit diagram showing a ATC Holder (empty) to battery pack (12V) with DC female power plugs coming off of it to the right the male plugs connect to a female cigarette socket. A male cigarette plug (car charger) connects to the USB meter with power lines connecting off the bottom of the image. All junctions are labeled as listed in the description.

Lesson 4 of 7 / 2-4 hours

This lab uses a variety of voltage conversion devices to output 5 Volts, the requirements for a USB charger such as for a cell phone. Students will take data on these devices and calculate, graph and compare efficiencies of different devices. Devices used in this lab are buck converters, which lower the input voltage and Boost Converters, which raise it (the Minty Boost® and Boost 500® are boost converters from Adafruit). These devices are available on the Internet and can be hard-wired to groups of series AA batteries. These devices frequently accept a range of input voltages, and some offer a range of output voltages. Students will be familiar with data collection from previous Off the Grid Lessons 1 and Lesson 3.

 

Off the Grid: Energy Transformations and Efficiency

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