Hello
I need to adj 12 voltage using LM317 or whatever regulator and then adjust the output voltage remotely like using Arduino and connect it to the computer then adj the voltage or using something like IR remote control to do it.
Thanks a lot
Re-read your message, imagining you have no idea what the project is about. I'm sure you notice, like me, that it doesn't make any sense.
What current is needed for this adjustable voltage output? Is this just a configurable output
reference voltage signal, or is this an adjustable power supply?
wvmarle:
Re-read your message, imagining you have no idea what the project is about. I'm sure you notice, like me, that it doesn't make any sense.
yes you're right
I'm kind of new to the electronic world
I just want to know is it possible to make such a thing to vary voltage between 6v - 12v remotely or with a computer.
MarkT:
What current is needed for this adjustable voltage output? Is this just a configurable output
reference voltage signal, or is this an adjustable power supply?
something between 1.2A - 1.5A
no, it's not a power supply it's just 0V - 12V or 6V - 12V (the lowest output voltage should be at last 6V any lower point it's not necessary) variable voltage output which I remotely adjustable
So you need a voltage regulator whose reference is controlled by a DAC.
1.2-1.5A that's a power supply, not a signal.
Indeed you'd need some kind of regulator. Considering the current I'd say some kind of switching regulator, the type would depend on a.o. the input voltage.
wvmarle:
1.2-1.5A that's a power supply, not a signal.Indeed you'd need some kind of regulator. Considering the current I'd say some kind of switching regulator, the type would depend on a.o. the input voltage.
We have 12V as input voltage.
Wirelessly or cabled?
Via internet?
How far away?
From the same room?
From the same house?
From the neighbors house?
From another city or even country?
GeronimoDK:
Wirelessly or cabled?
Via internet?
How far away?
From the same room?
From the same house?
From the neighbors house?
From another city or even country?
cabled
no
yes same place
just want to do it digitally like with software through the computer or with IR remote control or even pushbutton which is connected with wires to the circuit board
Key is to find a suitable voltage regulator. One that regulates its output based on a reference voltage. The 12V in, 12V out requirement makes this tricky: you probably have to look for a buck/boost type, rather than plain buck, as those typically have a minimum dropout of 1-2V.
Remote control is only one of your problems.
Pushbutton directly wired to the board is probably the easiest way to do it. Something like pushbutton 1, increase Vout by 0.1V, pushbutton 2 decrease. Have the pushbuttons on a long cable.
Through software on you computer could relatively easily be achieved via. HyperTerminal and then you have to decide how you serial interface needs to work, for example you could make it so you just type "2.5" and press ENTER and the Arduino then decodes that and outputs something useful to your regulator which will output 2.5V
If you want to do it with IR it's still doable, but you have to figure out a lot more things. For example what device exactly is it you want to control your circuit with? Remote for a TV or something like this? What is the modulation frequency (and you need to buy the fitting receiver for your device)?What is the bit-rate? What buttons do you want to use and what kind of data do those buttons send?
Next problem is your regulator, you could use a LM317 to achieve 6-12V for example, but that regulator has a dropout voltage somewhere between 1 and 2.5V (depends on current and temperature), that means if you supply it with 12V, you may only be able to output somewhere between 9.5V and 11V maximum!
This means you'd have to supply your LM317 regulator with something like 14.5V to be on the safe side and to be certain that you can output 12V.
Another thing that could be a problem is you cannot easily make the LM317 go below 1.2V on the output, so if you need 0V out you have to have a dual rail power-supply (meaning positive, ground and negative) which will complicate your setup further.
If you need exactly 12V in AND 12V out, you need to look for an adjustable switch mode regulator, they are more complicated to design an build. If you're lucky maybe you can buy a complete unit, but it will probably be more expensive than just a LM317 and a few passive components. But on the other hand it will also be more effective than the LM317 as you will lose a lot of power in your LM317 (you will need a good heat sink at 1.5A and lower voltages).
Also, you have to figure out how to control your regulator, it could be as "simple" as generating a reference voltage somehow, but how do you plan on doing that?
That reference could be created with a resistor ladder and a bunch of output pins.
It could be a digitally controlled voltage reference chip (or DAC).
Depending on the regulator and circuit maybe it could be PWM.
If your load is something simple (like a LED or maybe a motor) the solution could even be Arduino > PWM output > transistor (FET or MOSFET) > load! With this solution you don't even need a regulator...
So.... You have to make some choices! 
But you haven't even told us what you're really trying to achieve.
Linear regulators won't do.
OP mentioned a current of up to 1.5A. Dropping 12V to 6V means the device has to dissipate 9W of power. If using your 14.5V that'd be almost 13W. That's a lot of heat to deal with.
With a big heat sink you could probably still drop 13W in a LM317, maybe a heat sink with a small fan!
But still OP hasn't told us what he needs the adjustable voltage for, it could be that his load only uses 1.5A at 12V and the half at 6V, that would reduce the dissipated power a lot. It could be that he wants to make an adjustable voltage power supply for whatever testing purposes and really does need 6V 1.5A. But we don't know!
GeronimoDK:
But still OP hasn't told us what he needs the adjustable voltage for, it could be that his load only uses 1.5A at 12V and the half at 6V, that would reduce the dissipated power a lot. It could be that he wants to make an adjustable voltage power supply for whatever testing purposes and really does need 6V 1.5A. But we don't know!
That is what is called the "XY Problem". 
wvmarle:
Key is to find a suitable voltage regulator. One that regulates its output based on a reference voltage. The 12V in, 12V out requirement makes this tricky: you probably have to look for a buck/boost type, rather than plain buck, as those typically have a minimum dropout of 1-2V.
what if I use a boost converter to popup the voltage to about 16v - 19v and then use a buck converter to adj it in range of 6v - 12v
GeronimoDK:
Remote control is only one of your problems.
Pushbutton directly wired to the board is probably the easiest way to do it. Something like pushbutton 1, increase Vout by 0.1V, pushbutton 2 decrease. Have the pushbuttons on a long cable.Through software on you computer could relatively easily be achieved via. HyperTerminal and then you have to decide how you serial interface needs to work, for example you could make it so you just type "2.5" and press ENTER and the Arduino then decodes that and outputs something useful to your regulator which will output 2.5V
If you want to do it with IR it's still doable, but you have to figure out a lot more things. For example what device exactly is it you want to control your circuit with? Remote for a TV or something like this? What is the modulation frequency (and you need to buy the fitting receiver for your device)?What is the bit-rate? What buttons do you want to use and what kind of data do those buttons send?
Next problem is your regulator, you could use a LM317 to achieve 6-12V for example, but that regulator has a dropout voltage somewhere between 1 and 2.5V (depends on current and temperature), that means if you supply it with 12V, you may only be able to output somewhere between 9.5V and 11V maximum!
This means you'd have to supply your LM317 regulator with something like 14.5V to be on the safe side and to be certain that you can output 12V.
Another thing that could be a problem is you cannot easily make the LM317 go below 1.2V on the output, so if you need 0V out you have to have a dual rail power-supply (meaning positive, ground and negative) which will complicate your setup further.If you need exactly 12V in AND 12V out, you need to look for an adjustable switch mode regulator, they are more complicated to design an build. If you're lucky maybe you can buy a complete unit, but it will probably be more expensive than just a LM317 and a few passive components. But on the other hand it will also be more effective than the LM317 as you will lose a lot of power in your LM317 (you will need a good heat sink at 1.5A and lower voltages).
Also, you have to figure out how to control your regulator, it could be as "simple" as generating a reference voltage somehow, but how do you plan on doing that?
That reference could be created with a resistor ladder and a bunch of output pins.
It could be a digitally controlled voltage reference chip (or DAC).
Depending on the regulator and circuit maybe it could be PWM.If your load is something simple (like a LED or maybe a motor) the solution could even be Arduino > PWM output > transistor (FET or MOSFET) > load! With this solution you don't even need a regulator...
So.... You have to make some choices!
But you haven't even told us what you're really trying to achieve.
okay, I think using a couple of pushbuttons which is connected with cable is enough to increase and then decrease the voltage.
I don't need 0V I think 4.5V or anything near to that is pretty much enough for the lowest point of voltage.
my load is 3 fan which they're connected to the controller, but it's not how anything like PWN or anything else to provide an ability like change the fan speed smoothly it's just have a pushbutton to change it between lowest speed and the highest one.
last night I measured the power draw of the fans and it was about 10W (~0.9A @ 12V)
Paul__B:
That is what is called the "XY Problem".
yeah, you're right.
sorry for don't provide the full detail.
TonyStarkC10:
sorry for don't provide the full detail.
It's not too late. You can still do so. We've only just had one page of talk about the wrong solution to the problem.
What is that power used for? You suggest it's for regulating a fan speed, correct?
wvmarle:
It's not too late. You can still do so. We've only just had one page of talk about the wrong solution to the problem.What is that power used for? You suggest it's for regulating a fan speed, correct?
yes it has Molex connector which is connected to pc PSU but before that, I'm gonna use boost/buck converter and whatever needed to adjust the voltage to the fan controller Molex input
Reducing the voltage of a motor with a constant torque load by 50% will reduce the speed about 50%, but a fan is not constant torque, torque varies approximately with the square of speed, suggest testing effect of voltage variation to see what kind of voltage and current needed.
outsider:
Reducing the voltage of a motor with a constant torque load by 50% will reduce the speed about 50%, but a fan is not constant torque, torque varies approximately with the square of speed, suggest testing effect of voltage variation to see what kind of voltage and current needed.
Thank you, I have been tested it and at the highest speed, it needs about 10W (~0.9A @ 12V) and the fans start spinning at something about 2.5V.
A boost then a buck converter sounds like the wrong solution any day. Not only because there actually are boost/buck type converters which can output the same voltage as on their input, it's also because you would normally control the current through a device directly, not through trying to manipulate its voltage.
Many fans can be controlled just fine using PWM instead. Much easier. All you need is a MOSFET and two resistors. Very easy for an Arduino to produce such a signal.
Some computer fans actually have a speed control signal and have this speed control built in. Even easier. That speed control signal is usually PWM or similar kind of block wave, which again an Arduino can easily produce.
The problem still is that we're 18 posts in and finally at least we know you're trying to control the speed of a fan, but we still don't know exactly what fan (part number).
Indeed, sounds like this is yet another example of an XY problem...