Does buck converter without adjustable ampere can be modified?

Thread Starter

Gembrotai

Joined Jul 2, 2019
28
Hhhm
I use 18650 battery for the input about 5x2200 mAH. I just confused about the current that too high. I just need the output for router 9v and 0,6 amp.
 

MrAl

Joined Jun 17, 2014
7,792
If you have to add your own current limit then you have to have a schematic or can make one. You have to at least know the controller chip being used.
It does not sound like you need current limit for this though are you sure you do?
 

Thread Starter

Gembrotai

Joined Jul 2, 2019
28
If you have to add your own current limit then you have to have a schematic or can make one. You have to at least know the controller chip being used.
It does not sound like you need current limit for this though are you sure you do?
I just want to make an adjustable voltage and ampere. I tried use potensiometer to limit the current from battery set. Or do you know how to make ampere and voltage regulator???
 

crutschow

Joined Mar 14, 2008
25,367
If the load is a 9V router that takes 0.6A, then you just adjust the voltage to 9V and the router will take the current it needs.

You don't need to limit the current.
Why do you think you do????
 
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Thread Starter

Gembrotai

Joined Jul 2, 2019
28
View attachment 15806262828252154323310376846612.jpg
Why not???
A buck converter is just a type of voltage regulator.
Man, it works. Thanks a lot.
Will it save for the router????? I thought the ampere will broke the router.

The truth is iam working this project for my university and i must write it down the detail. Could you please help me find the source for the information about this case???? Please...
 

MrAl

Joined Jun 17, 2014
7,792
I just want to make an adjustable voltage and ampere. I tried use potensiometer to limit the current from battery set. Or do you know how to make ampere and voltage regulator???
Yes myself an others i am sure know how to add current limit to a general power supply, but if you are talking about a ethernet router i dont think you need to add current limit because the router should only draw as much current as it needs.
What did you measure that makes you think you need to limit current? Did something burn up or heat up significantly? Or did the current just "seem" to be too high?
 

Thread Starter

Gembrotai

Joined Jul 2, 2019
28
Yes myself an others i am sure know how to add current limit to a general power supply, but if you are talking about a ethernet router i dont think you need to add current limit because the router should only draw as much current as it needs.
What did you measure that makes you think you need to limit current? Did something burn up or heat up significantly? Or did the current just "seem" to be too high?
When i measure the current with multitester without connect it to router, it is to high more than 10 amp. Because that, my multitester was burning.
And why router doesn't need current limit? And when device need current limit?
Please help me with this case, i wanna be an expert in electronics. I wanna learn with you all...
 

MrAl

Joined Jun 17, 2014
7,792
When i measure the current with multitester without connect it to router, it is to high more than 10 amp. Because that, my multitester was burning.
And why router doesn't need current limit? And when device need current limit?
Please help me with this case, i wanna be an expert in electronics. I wanna learn with you all...
Some things operate based mostly on voltage, other things operate mostly on current, and some things operate on both at the same time.

An example of mostly voltage is a light bulb. Most light bulbs work on a voltage and they just draw whatever current they were designed to draw so you do not normally need current limit.

An example of mostly current is an LED. An LED really needs a set current level to work best.

An example of both is a fluorescent lamp that needs a certain voltage but with a current limiting circuit also.

But most things we have at home just need a set voltage and once you supply the correct voltage it just works because it only draws a small amount of current.

But when you try to measure your battery with your meter, you are testing the maximum current you can get out of the battery not the current the router will draw when operating normally.
So dont do that. :)

Yes, there could be something wrong with the router but most likely there is not and it will work fine. If you are worried, try to run something cheaper off of the battery or power supply like a small bulb rated for 9vdc.
 

Alec_t

Joined Sep 17, 2013
11,627
It is a common misconception that a power supply rating of, say 10A (10 Amps), means that the supply will always push 10A through a connected load. The rating merely indicates the maximum current the supply is designed to provide without damaging itself.
I suggest you read up on the basics of electronics, for example here.
 

Thread Starter

Gembrotai

Joined Jul 2, 2019
28
Some things operate based mostly on voltage, other things operate mostly on current, and some things operate on both at the same time.

An example of mostly voltage is a light bulb. Most light bulbs work on a voltage and they just draw whatever current they were designed to draw so you do not normally need current limit.

An example of mostly current is an LED. An LED really needs a set current level to work best.

An example of both is a fluorescent lamp that needs a certain voltage but with a current limiting circuit also.

But most things we have at home just need a set voltage and once you supply the correct voltage it just works because it only draws a small amount of current.

But when you try to measure your battery with your meter, you are testing the maximum current you can get out of the battery not the current the router will draw when operating normally.
So dont do that. :)

Yes, there could be something wrong with the router but most likely there is not and it will work fine. If you are worried, try to run something cheaper off of the battery or power supply like a small bulb rated for 9vdc.
as i learn from you,
1. there are devices doesn't need to be limited the current
2. try to measure the current from output buck converter that i have isn't measuring the router ampere

i have questions here and everyone can help me to answer these
1. how about using it to charge a phone? is it save?
2. how to build current limit this project? as i know there are various buck converter also with the adjustable current
3. how to add reverse input protection on this project?
4. i have mini dual voltmeter and ammeter with 10 amp max, but when i try apply the current point it will ground the buck converter. how to add this to my project?

thanks all for your time to help and teach me....
 

Thread Starter

Gembrotai

Joined Jul 2, 2019
28
It is a common misconception that a power supply rating of, say 10A (10 Amps), means that the supply will always push 10A through a connected load. The rating merely indicates the maximum current the supply is designed to provide without damaging itself.
I suggest you read up on the basics of electronics, for example here.
so as long the device current needs doen't through more than the max buck converter current it will save an ok?
and is there more specific load that need current limit?
 

crutschow

Joined Mar 14, 2008
25,367
1. how about using it to charge a phone? is it save?
It's safe as long as the voltage is correct for the phone charger.
2. how to build current limit this project? as i know there are various buck converter also with the adjustable current
You either buy a converter with a built-in limiter, or you need the schematic of the one you have to see if it can be added.
3. how to add reverse input protection on this project?
Is that for the input to the converter?
If so, you could add a Schottky diode in series with the input or, for essentially zero voltage drop, you could use a P-MOSFET with the source terminal to the supply, the gate terminal to ground, and the drain terminal as the power input.
4. i have mini dual voltmeter and ammeter with 10 amp max, but when i try apply the current point it will ground the buck converter. how to add this to my project?
An ammeter always is connected in series with whatever you want to measure (in this case the output).
An ammeter has a very low resistance so it can measure current without significantly disturbing the current.
It's never connected to ground, which applies a short to the circuit, as you did with your multimeter (which can damage the meter).
 

MrAl

Joined Jun 17, 2014
7,792
as i learn from you,
1. there are devices doesn't need to be limited the current
2. try to measure the current from output buck converter that i have isn't measuring the router ampere

i have questions here and everyone can help me to answer these
1. how about using it to charge a phone? is it save?
2. how to build current limit this project? as i know there are various buck converter also with the adjustable current
3. how to add reverse input protection on this project?
4. i have mini dual voltmeter and ammeter with 10 amp max, but when i try apply the current point it will ground the buck converter. how to add this to my project?

thanks all for your time to help and teach me....
1. I would say stay away from trying to charge a phone from a source that is not yet known to
work properly with the phone. Modern phones have a much more sophisticated system for charging that
require negotiations with the source. Besides, any experiment could burn something out. The
best bet is to use what came with the phone or get an identical unit as there are many different
spec's these days that are sometimes specific to the company that made the phone and the model
number. You'll find quite a variation these days.
2. If you want to build a current limited buck you may have to start from scratch if you can
not find a schematic of your current PC board.
3. Reverse input protection comes in different ways. The simplest is a series diode.
4. When you use a volt meter you place the leads ACROSS the power supply, but when you use
a current meter you place the leads such that the meter is in SERIES with the load. So the
current meter never touches both terminals of the power source.
If you have a dual voltmeter and current meter it depends on the wiring of the two meters.
Sometimes you are forced to have the current meter in the ground line in series with the load.
You will have to specify the model of the meter you are using.
 

djsfantasi

Joined Apr 11, 2010
6,783
There is a LOT of good information here. In summary...
  1. A device usually only pulls the current it needs. The power supply rating is the maximum it can supply
  2. Some devices do need current limiting. LEDs and smartphones for example. LEDs are easier. Smartphones need additional circuitry
  3. Current is measured in series with a load. Voltage is measured across the load, and will differ depending on what two points you choose
  4. Learn Ohms Law
 

dendad

Joined Feb 20, 2016
3,602
When i measure the current with multitester without connect it to router, it is to high more than 10 amp. Because that, my multitester was burning.
And why router doesn't need current limit? And when device need current limit?
Please help me with this case, i wanna be an expert in electronics. I wanna learn with you all...
Yes, that is correct. If you place your amp meter across the output of the power supply, it is almost a short circuit and the power supply will try to source as much current as it can to keep the voltage constant.
NEVER hook a current meter across the power supply. It should go in series with the load.

The current drawn depends on the voltage and the resistance.
Just think of a car 12V battery.
The starter motor can draw 100Amps but the dash clock only a few mA. Both are on the same battery.
A 10Amp power supply is rated to supply loads up to 10 Amps. That could be one 10A load, or 20 x 0.5A loads.
The voltage regulated 10Amp supply will not force 10Amps into the load.
 

Thread Starter

Gembrotai

Joined Jul 2, 2019
28
as time pass, this project has been accepted on my university as thesis. I appreciate all of you guys, thanks a lot.
Iam from Indonesia and just graduated from STT-PLN or IT-PLN this year (bachelor degree). This project is a good one and i get A.
If anyone try to learn this, i have uploaded my thesis for reference.
Now I need to find a work, hope that any companies or universities will be interested in me.
Thanks a lot guys.

If you want to cantact me:
Email: <mod: Deleted email>
Personal Instagram:
My Startup Instagram:

Keyword:
#Skripsi #STT-PLN #ITPLN #ATSDC #AutomatictransferswitchDC #Powerbankforrouter #Powerbankformodem # ModemATS #Tugasakhir #Sarjana #TeknikElektro #Jakarta #Indonesia #RouterATS #PMMBbatch2 #MagangICON+ #Faultmanagement #Aruslemah #Yariscourses
 

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