I built small Laptop Boost Converter Last month, and wanted to post the Schematic for you DIY'ers that want to build one for yourselves.
Input Range is 8V-18V (10V-14.4V Recommended) And does not require a POT to get the volts you need. I recommend cherry-picking (with an ohmmeter) the lowest ohm 15K resistor and highest ohm 1K for the feedback circuit. Oscillation frequency approximately 100Khz.
I use it to run my Laptop from a 12V 4.5AH AGM SLA Battery in my laptop bag to save on running down the internal laptop battery. If my Laptop Battery is full I get 2.5HRS Runtime . If I am charging the internal battery, the time is much shorter, so I recommend running with a full battery.
It was made simply by taking a PCB out of a 12V to 5V Cellphone charger, and modifying it to run a MOSFET and changing some of the parts values. I then built it on to a small heatsink as the chassis.
I see lots of people wanting to build a boost for laptop, so here is a simple one for everyone to enjoy!
Input Range is 8V-18V (10V-14.4V Recommended) And does not require a POT to get the volts you need. I recommend cherry-picking (with an ohmmeter) the lowest ohm 15K resistor and highest ohm 1K for the feedback circuit. Oscillation frequency approximately 100Khz.
I use it to run my Laptop from a 12V 4.5AH AGM SLA Battery in my laptop bag to save on running down the internal laptop battery. If my Laptop Battery is full I get 2.5HRS Runtime . If I am charging the internal battery, the time is much shorter, so I recommend running with a full battery.
It was made simply by taking a PCB out of a 12V to 5V Cellphone charger, and modifying it to run a MOSFET and changing some of the parts values. I then built it on to a small heatsink as the chassis.
I see lots of people wanting to build a boost for laptop, so here is a simple one for everyone to enjoy!
Attachments
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PICTURES
I wanted to post pictures.
Pictures of BATTERIES, converter closeups, converter wrapped in tape (for protection, and my setup for unplugging the laptop power cord from the 120V AC adapter and connecting it to my 19.5V DC adapter.
Also my Laptop Bag, and my batteries and boost converter go in the front pouch.
19.70V UNLOADED
19.57V LOADED
This is my compact DC adapter, as I built a larger TL494-Based Push-Pull one a year ago, and will get pictures of that one up soon.
I wanted to post pictures.
Pictures of BATTERIES, converter closeups, converter wrapped in tape (for protection, and my setup for unplugging the laptop power cord from the 120V AC adapter and connecting it to my 19.5V DC adapter.
Also my Laptop Bag, and my batteries and boost converter go in the front pouch.
19.70V UNLOADED
19.57V LOADED
This is my compact DC adapter, as I built a larger TL494-Based Push-Pull one a year ago, and will get pictures of that one up soon.
Attachments
Wanted to add for searchability......boost controller uses MC34063 which makes this easy for anyone trying to DIY an SMPS because the 34063 is so common, and it is not hard to re-purpose a circuit with one in it, simply by changing the feedback, make it drive a MOSFET, and remove unnecessary components. Easy, reliable, cheap. Can't go wrong.
nice project.
The switchers get names like full bridge or half bridge.
What topology have you used, where only one FET is used as the switcher?
Are there any alternative names that manufacturers would use in a description?
The switchers get names like full bridge or half bridge.
What topology have you used, where only one FET is used as the switcher?
Are there any alternative names that manufacturers would use in a description?
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looked up flyback converter.
Wiki won't let me copy and paste the diagram.
http://upload.wikimedia.org/wikiped...ntions.svg/1052px-Flyback_conventions.svg.png
from this page
http://en.wikipedia.org/wiki/Flyback_converter
The S is the mosFET.
The primary of the transformer is the inductor.
But is this always called a flyback converter?
Is that what you are telling me?
Does a flyback converter ALWAYS look like this?
Would everyone familiar with switchers know what topology one is referring to if they describe as "flyback converter"?
Wiki won't let me copy and paste the diagram.
http://upload.wikimedia.org/wikiped...ntions.svg/1052px-Flyback_conventions.svg.png
from this page
http://en.wikipedia.org/wiki/Flyback_converter
The S is the mosFET.
The primary of the transformer is the inductor.
But is this always called a flyback converter?
Is that what you are telling me?
Does a flyback converter ALWAYS look like this?
Would everyone familiar with switchers know what topology one is referring to if they describe as "flyback converter"?
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The Flyback Converter
http://ecee.colorado.edu/ecen4517/materials/flyback.pdf
fig1 of this seems to be saying that a & b are not flyback and that c & d are flyback.
Is this correct?
Does fig1 a, mean that the post1 circuit is referred to as a buck-boost converter? A similar term to what EW uses.
http://ecee.colorado.edu/ecen4517/materials/flyback.pdf
fig1 of this seems to be saying that a & b are not flyback and that c & d are flyback.
Is this correct?
Does fig1 a, mean that the post1 circuit is referred to as a buck-boost converter? A similar term to what EW uses.
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http://www.ti.com/lit/ds/symlink/tl497a.pdf
In a buck-convertor (booster) a transformer is not required, only a suitable choke.
In a buck-convertor (booster) a transformer is not required, only a suitable choke.
A XTW-SY-8 pcb with XL6009 may be a much easier starting point, as the main switchmode current loops are carefully managed, compared to a birds-nest approach.
As with all switchmodes, some extra management of switching ripple and noise may be needed, but at least there is a constrained layout to work with.
Any supply working from a rechargeable battery would really benefit from a low voltage cutout mechanism.
As with all switchmodes, some extra management of switching ripple and noise may be needed, but at least there is a constrained layout to work with.
Any supply working from a rechargeable battery would really benefit from a low voltage cutout mechanism.
In a way, it has an under-voltage cutout, the fact that with the VBE drop of both chip and totem-pole driver stage, gets below the required gate-drive volts of the MOSFET when the battery gets low. I have had no issues with my batteries.
(although, I am tempted to experiment with running the 34063 from the boosted 19.5V Rail instead, to get a bit more from the batteries in an emergency situation)
And to answer AndrewT's questions, yes its a DC boost topology (aka single winding flyback) but instead of using the 34063 chip as the SMPS itself, I am using it as a control chip only for driving the MOSFET.
Any other tip I have with this circuit, I recommend when building this converter, connect to to the BATTERY FIRST, then plug in the laptop, that way the volts are already built up to avoid a large startup surge from the pulse-width starting off at max (no softstart).
It is simple for the DIY'er because the 34063 chip is in nearly EVERY car charger for USB or Cellphone, and can be easily used for bigger and better projects.
(although, I am tempted to experiment with running the 34063 from the boosted 19.5V Rail instead, to get a bit more from the batteries in an emergency situation)
And to answer AndrewT's questions, yes its a DC boost topology (aka single winding flyback) but instead of using the 34063 chip as the SMPS itself, I am using it as a control chip only for driving the MOSFET.
Any other tip I have with this circuit, I recommend when building this converter, connect to to the BATTERY FIRST, then plug in the laptop, that way the volts are already built up to avoid a large startup surge from the pulse-width starting off at max (no softstart).
It is simple for the DIY'er because the 34063 chip is in nearly EVERY car charger for USB or Cellphone, and can be easily used for bigger and better projects.
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