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  • Author Author: Jan Cumps
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Experimenting with Magnetic Components - Boost Converter part 2: Build

Jan Cumps

I'm reviewing a set of inductors for the Experimenting with Magnetic Components design challenge.

Because it's a design challenge, I'd like to start with a working product. A switch mode DC converter.

It's one of the standard circuits: the boost converter. A design that increases a DC voltage.

 

 

In post 1, I checked the schematics and the inductor. Here I'm building and testing the design.
image

 

Building the Boost Converter on a Proto Board

 

With the shopping basket I won in a Project14 contest, I bought a set of copper clad PCBs.

I used a box cutter to carve islands.

The transistor and diode come from my limited pile of recycle parts.

image

 

Instead of clipping the component leads, I used them as the connection and probe points.

I used a standard solder iron (no station) and leaded solder.

I used an oscilloscope, but in essence you only need a DC 9 - 12 V power supply, a function generator that can generate block waves with more then 8 Vpp, and a voltmeter.

Check 's comment on a trap for young players when building a boost converter without feedback. I mitigated it by having the load always connected (it's soldered on the board).

 

Components:

 

L: Bourns RLB Series 1mH Radial Lead InductorBourns RLB Series 1mH Radial Lead Inductor

CIN: 120 µF 25 V

RGATE: 3.6 K

Q: 2SK2632LS N-CHannel MOSFET

D: SB360 SCHOTTKY BARRIER DIODE

COUT: 4.7 µF 450 V

RL: 2.7 K 2 W (this resistor dissipates up to 1.33 W when VOUT = 60 V)

 

I reviewed the inductor (part #6 of the kit for this design challenge) in the previous post.

 

MOSFET 2SK2632LS2SK2632LS

The MOSFET package is isolated. The heatsink can safely touch the PCB ground plane.

It's overkill for this circuit (like all other components, it's what I had lying around).

It is designed for switching, is fast and has a low RON.

 

image

I'm driving the transistor with VGS = 18 V.

VDS(max) = VOUT(max) = 60 V

ID(max) = VOUT(max) / RL = 60 V / 2.7 K = 22 mA

 

Schottky Diode SB360SB360

Again overkill. With the components I put in this experiment, and a larger capacitor, you could generate higher current.

image

 

First Test

 

I've tested the board, with 9 V input, 72 KHz 18 VPP  block signal with 80% duty cycle.

The output was 32 V.

image

I'll do some more measurements in part 3, related to ripple.

 

 

Related posts
1. Boost Converter part 1: Inductor and Calculations
2. Boost Converter part 2: Build
3. Boost Converter part 3: Measure the Inductor in action
4. LCR meter experiments
5. SMD transformers experiment gizmo part 1: Build
6. SMD transformers experiment gizmo part 2: Measure
7. Common Mode Choke
8. Make your own Inductor
9. Calculate your own Inductor
10. Boost Converter part 4: Efficiency
11. DIY Inductance Meter
Planar PCB Transformer: GaN Point of Load converter 48V to 1V 50A
Measure Unknown Inductor Value with Function Generator and Oscilloscope
Experimenting with Magnetic Components: About the Competition
Parents

  • I'm preparing to measure current through the inductor.

     

    I have an island on the clad board that can be used for that.

    I can pivot one pin of either the inductor or the diode to that island. Then put a current meter between that island and the original mount point.

    image

     

    Here is the setup to measure the current through the inductor:

    image

    And this is the adapted schematic:

    image

    Best to have the current meter always connected. An inductor with the current path removed can behave funny.

Comment

  • I'm preparing to measure current through the inductor.

     

    I have an island on the clad board that can be used for that.

    I can pivot one pin of either the inductor or the diode to that island. Then put a current meter between that island and the original mount point.

    image

     

    Here is the setup to measure the current through the inductor:

    image

    And this is the adapted schematic:

    image

    Best to have the current meter always connected. An inductor with the current path removed can behave funny.

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