if I use it on its side.
with the output wires being attatched in this way
the loads negative is connected to the INPUT POSITIVE of the boost converter
With the loads positive connected to the POSITIVE OUTPUT of the boost converter
And by turning the pot i am able to buck AND boost with this supposedly "BOOST-ONLY" DC-DC converter with great efficiency
Only quirk is the voltage jumps up a bit when you detach the input power supply (with a very small or no load on the output)
How is it possible that this works in this way?
Its only got a SINGLE inductor.
if I turn the pot all the way down i even get -0.2v!!
I tested with my multimeter with the pot set to 0v and slowly raised it and it maxed out at 5.5A before the puny schottky diode got SEARING hot and i unplugged my multimeter right away. No smoke was emitted.
its still working and fine though. conducts at around 0.1v to 0.2v so no permanent damage.
When using a 12v power supply rated 2 amps.
it easily output 5.5A when bucking the voltage down in this configuration.
so its absolutely working in some way.
I replaced the inductor with a toroidal one rated for much higher current as well so its got a good inductor and the inductor stays cool at all current levels.
I'm not sure how its able to do this but it seems really interesting..
I did originally pay for a buck AND boost converter.
but thinking I only received a boost converter because I could only see one inductor I never tried messing with it in this way until now.
it works extremely well for bucking the voltage from a 20W 21.6v solar panel down to 5v or 12v or anything.
I can buck and boost on the fly with it in this configuration!
Is this a well known thing or is this possibly an exception?
For further clarity
the input power + and - of the DC-DC converter are connected
with the LOAD'S negative to the input's positive.
And the loads POSITIVE to the outputs positive.
How is it possible this is working in this configuration? I'm really confused and curious.
with the output wires being attatched in this way
the loads negative is connected to the INPUT POSITIVE of the boost converter
With the loads positive connected to the POSITIVE OUTPUT of the boost converter
And by turning the pot i am able to buck AND boost with this supposedly "BOOST-ONLY" DC-DC converter with great efficiency
Only quirk is the voltage jumps up a bit when you detach the input power supply (with a very small or no load on the output)
How is it possible that this works in this way?
Its only got a SINGLE inductor.
if I turn the pot all the way down i even get -0.2v!!
I tested with my multimeter with the pot set to 0v and slowly raised it and it maxed out at 5.5A before the puny schottky diode got SEARING hot and i unplugged my multimeter right away. No smoke was emitted.
its still working and fine though. conducts at around 0.1v to 0.2v so no permanent damage.
When using a 12v power supply rated 2 amps.
it easily output 5.5A when bucking the voltage down in this configuration.
so its absolutely working in some way.
I replaced the inductor with a toroidal one rated for much higher current as well so its got a good inductor and the inductor stays cool at all current levels.
I'm not sure how its able to do this but it seems really interesting..
I did originally pay for a buck AND boost converter.
but thinking I only received a boost converter because I could only see one inductor I never tried messing with it in this way until now.
it works extremely well for bucking the voltage from a 20W 21.6v solar panel down to 5v or 12v or anything.
I can buck and boost on the fly with it in this configuration!
Is this a well known thing or is this possibly an exception?
For further clarity
the input power + and - of the DC-DC converter are connected
with the LOAD'S negative to the input's positive.
And the loads POSITIVE to the outputs positive.
How is it possible this is working in this configuration? I'm really confused and curious.
Well its easy to make one with just a simple 555 timer and a mosfet or transistor and an inductor.
I even made one with a speaker. a 6v battery. a transformer. a diode and capacitor.
and used the speaker as an oscillator.
And it boosted the 6v to over over 14v with 24v+ peaks
It was loud and noisy but it worked lol.
Now to make a buck converter would be more difficult.
My only thing im curious about is how it can buck and boost even though its only meant to BOOST the voltage.
How is it possible it can do both from a single inductor?? I find it super amazing and really useful. Now I dont need to buy a buck/boost converter anymore!
I hand-wound the inductor so its not totally as perfect as it could be but its still plenty close enough and it works great. with no overheating inductor and improved efficiency.
I even made one with a speaker. a 6v battery. a transformer. a diode and capacitor.
and used the speaker as an oscillator.
And it boosted the 6v to over over 14v with 24v+ peaks
It was loud and noisy but it worked lol.
Now to make a buck converter would be more difficult.
My only thing im curious about is how it can buck and boost even though its only meant to BOOST the voltage.
How is it possible it can do both from a single inductor?? I find it super amazing and really useful. Now I dont need to buy a buck/boost converter anymore!
I hand-wound the inductor so its not totally as perfect as it could be but its still plenty close enough and it works great. with no overheating inductor and improved efficiency.
realflow100 said:
So, let me get this straight: you bought a buck and boost converter, but now express surprise that you got a buck and boost converter?realflow100 said:
I suspect physics, as applied in circuit theory?
The problem was it IS only a "boost" converter when I received it
it advertised a 2 inductor buck boost converter even in the photo.
but what I received was intended as a boost-only DC-DC converter and it came with only one inductor (and of different value) so they sent the wrong thing.
and I still made it work as a buck/boost converter by using it in an unintended way by ignoring the correct way to use it with both negative and positive outputs
and using it this weird way where im using it on its side.
so input like normal
but output is attached to positive input and positive output leads and ignoring the negative output lead coming off the DC-DC converter
and for some reason when using it like this. it acts just like a buck/boost converter. although the maximum voltage is only about 35v. rather than 40-50v in boost-only mode
I call it buck/boost mode
because its able to boost and buck at the same time when hooked up this way.
I didn't really change anything on the circuit for it to do this. just changed where i got output from.
it advertised a 2 inductor buck boost converter even in the photo.
but what I received was intended as a boost-only DC-DC converter and it came with only one inductor (and of different value) so they sent the wrong thing.
and I still made it work as a buck/boost converter by using it in an unintended way by ignoring the correct way to use it with both negative and positive outputs
and using it this weird way where im using it on its side.
so input like normal
but output is attached to positive input and positive output leads and ignoring the negative output lead coming off the DC-DC converter
and for some reason when using it like this. it acts just like a buck/boost converter. although the maximum voltage is only about 35v. rather than 40-50v in boost-only mode
I call it buck/boost mode
because its able to boost and buck at the same time when hooked up this way.
I didn't really change anything on the circuit for it to do this. just changed where i got output from.
Last edited:
Hey thanks for sharing. I just tried it with two different boosters and it works for both exactly as you described. Pretty sweet.
TM
TM
I wonder how its possible! its really useful!
It seems it works based on the voltage being boosted above the input voltage.
and so if its 5v input and you boost it to 6v you'll get around 0.5 to 1v on the side-output
and boosting to 7.5v (real output) you would get about 2.5v on ouput from the side
You can also boost as well. just keep turning the pot.
the voltage isnt quite stable though. You need a reasonably stable input but it does work.
Why dont more people know about this? No one would be making buck boost converters anymore.. Just boost converters with a buck/boost mode and a boost mode by simply changing where you get the output from.
All it'd require is an automatic built in switch or something. and could be done with just a single inductor (I hand-wound my inductor myself so i know for sure theres only one inductor!)
This is super useful and really good if you have a high powered 150W or so boost converter. Now those would be able to buck with VERY HIGH CURRENTS no problem!
It seems it works based on the voltage being boosted above the input voltage.
and so if its 5v input and you boost it to 6v you'll get around 0.5 to 1v on the side-output
and boosting to 7.5v (real output) you would get about 2.5v on ouput from the side
You can also boost as well. just keep turning the pot.
the voltage isnt quite stable though. You need a reasonably stable input but it does work.
Why dont more people know about this? No one would be making buck boost converters anymore.. Just boost converters with a buck/boost mode and a boost mode by simply changing where you get the output from.
All it'd require is an automatic built in switch or something. and could be done with just a single inductor (I hand-wound my inductor myself so i know for sure theres only one inductor!)
This is super useful and really good if you have a high powered 150W or so boost converter. Now those would be able to buck with VERY HIGH CURRENTS no problem!
Last edited:
I think this hook up method inverts the voltage that the chip sense pin sees at the voltage divider (the pot). I like it! Very useful.
TM
TM
Well it doesn't really change how the chip operates. but it does change how you get the voltage output of it. sometimes you'll get a voltage spike depending how good the boost converter is made. Usually only when turning it off or if its running in current limited mode. so be careful with light loads or sensitive loads.
For heavier loads over 20 to 100mA and above it shouldn't be a problem.
For heavier loads over 20 to 100mA and above it shouldn't be a problem.
AFAIK it's a common method for driving a led
as you wrote the output "0V" now sitting at input V+ which is bit tricky when the output connected to "something else" that have a real 0V/GND which can make a dead short
for LED it's acceptable beacuse load at the end of chain
as you wrote the output "0V" now sitting at input V+ which is bit tricky when the output connected to "something else" that have a real 0V/GND which can make a dead short
for LED it's acceptable beacuse load at the end of chain
Attachments
I'd only use one output or the other but not both at once.
it works great for reducing 12v to 5v to run my audio amplifier or run a small DC motor like a PC fan motor.
it works great for reducing 12v to 5v to run my audio amplifier or run a small DC motor like a PC fan motor.
Main drawback is your output is not properly regulated
Any fluctuation at input will be followed by output in reverse, because Boost Controller Vfb is reading actual output (GND Reference)
Any fluctuation at input will be followed by output in reverse, because Boost Controller Vfb is reading actual output (GND Reference)
What makes you think you can identify a buck/boost converter by the number of it's inductors? Actually only one inductor is needed that lays somewhere between the input and output terminals. Buck and boost converters solely are discerned by their arrangement of switching devices. So, if you place all devices that are needed for both types around your inductor and drive them properly, your converter will either buck or boost on demand.
Best regards!
Best regards!
I know thats the problem.
You need a reasonably stable input (which is fine in my case since im using a 2A 12v wall wart with decent voltage stability under load.)
but it works fine
And i'm just saying in general most of the buck/boost converters I see are using two separate inductors
so I'm just going on what ive seen. How would you get a buck boost converter with a single inductor working with regulation on boosting AND buck control?
just a bit confusing.
You need a reasonably stable input (which is fine in my case since im using a 2A 12v wall wart with decent voltage stability under load.)
but it works fine
And i'm just saying in general most of the buck/boost converters I see are using two separate inductors
so I'm just going on what ive seen. How would you get a buck boost converter with a single inductor working with regulation on boosting AND buck control?
just a bit confusing.
Many kits with dual inductor usually a SEPIC Converter
Kind a "buck-boost" but different topologies
Kind a "buck-boost" but different topologies
- Status
- Not open for further replies.