How to regulate a DC voltage without interruptions?

[HomeExperiement]

Hi!

I learned that all or at least majority DC voltage regulators such as step down module work by interrupting DC at some intervals. However, if I am interested in continuous DC, is it possible to make such voltage regulator that doesn't interrupt voltage at given intervals? Or what would happen if I installed interrupting dimmer switch before PSU? Will it start giving out lower voltage where interruptions are smoothed out by capacitors or will it be garbage idea?

 

[anorlunda]

How many volts/amps/watts are you talking about? If it is small enough, an IC chip might do the job. If it is big enough, a motor-generator set is needed. There's lots of room between those extremes.

 

[Borek]

While impulse regulators work by switching the current on/off, they often have a capacitor (or coil) that removes the ripples, so what they produce is a quite nice DC.

As @anorlunda wrote, there are limits to what can be done this way.

 

[HomeExperiement]

How many volts/amps/watts are you talking about? If it is small enough, an IC chip might do the job. If it is big enough, a motor-generator set is needed. There's lots of room between those extremes.

Right now about 90W at 12V. But it could be more some time later.

While impulse regulators work by switching the current on/off, they often have a capacitor (or coil) that removes the ripples, so what they produce is a quite nice DC.

As @anorlunda wrote, there are limits to what can be done this way.

Can you link me few products and/or scheme how it works (like how and where to exactly connect it)?

 

[phinds]

Hi!

I learned that all or at least majority DC voltage regulators such as step down module work by interrupting DC at some intervals. However, if I am interested in continuous DC, is it possible to make such voltage regulator that doesn't interrupt voltage at given intervals? Or what would happen if I installed interrupting dimmer switch before PSU? Will it start giving out lower voltage where interruptions are smoothed out by capacitors or will it be garbage idea?

Define "smoothed out". That is, you need to know how much ripple your application can stand. It might well be more than you think ("ripple" being far less invasive than straight on-off chopping).

 

[anorlunda]

Or what would happen if I installed interrupting dimmer switch before PSU?

Wait a minute. Are you asking about a DC to DC voltage converter, or an AC to DC power supply?

 

[phinds]

Wait a minute. Are you asking about a DC to DC voltage converter, or an AC to DC power supply?

I've been reading this that he's talking about a DC/DC converter

 

[rbelli1]

like how and where to exactly connect it

They come built in as as integral (and necessary) part of the operation of the power supply.

BoB

 

[GrahamN-UK]

I learned that all or at least majority DC voltage regulators such as step down module work by interrupting DC at some intervals. However, if I am interested in continuous DC, is it possible to make such voltage regulator that doesn't interrupt voltage at given intervals? Or what would happen if I installed interrupting dimmer switch before PSU? Will it start giving out lower voltage where interruptions are smoothed out by capacitors or will it be garbage idea?

I'll go with garbage idea. If you want a DC power supply with variable output just buy one with that feature built in (you can google for the specifications you want to find some). Don't try to lash something together with a dimmer switch.

Also, are you looking for a power supply that takes AC mains in and outputs 12 V DC at 90 W or a DC convertor that takes in a relatively low DC voltage and converts it to 12 V? Those are two different classes of device and you should get whichever one you need.

DC regulators that work by regularly interrupting the DC supply are known as switch-mode power supplies (SMPS). If you are running them within their ratings they rebuild the output DC to be continuous.

 

[davenn]

Hi!

I learned that all or at least majority DC voltage regulators such as step down module work by interrupting DC at some intervals. However, if I am interested in continuous DC, is it possible to make such voltage regulator that doesn't interrupt voltage at given intervals? Or what would happen if I installed interrupting dimmer switch before PSU? Will it start giving out lower voltage where interruptions are smoothed out by capacitors or will it be garbage idea?

Can you link me few products and/or scheme how it works (like how and where to exactly connect it)?

Before your point 2 is done, you need to more clearly state what you are trying to achieve

As others have asked/stated ... we don't really know if you are talking about AC to DC conversion or DC - DC conversion ( tho this one seems more likely)

Your original post shows that you may misunderstand how DC - DC converters work.
So before others respond with suggestions that may be off track, PLEASE let us all know what you are doing Dave

 

[Rive]

I learned that all or at least majority DC voltage regulators such as step down module work by interrupting DC at some intervals.

You have learned just half of the stuff there. The other half is, that usually there are further components to make that pulsed thing nice continuous DC again, at the required output voltage. Your worries are almost entirely baseless.

what would happen if I installed interrupting dimmer switch before PSU? Will it start giving out lower voltage

Usually DC voltage regulators has reference components built in. If it is possible they try to keep the output voltage stable, compared to that reference. So, as long as the input voltage is any useful (for the actual circuit), the output voltage won't change.

 

[jim hardy]

However, if I am interested in continuous DC, is it possible to make such voltage regulator that doesn't interrupt voltage at given intervals?

for low power applications this series of "Linear" regulators is popular.
http://www.ti.com/lit/ds/symlink/lm340.pdf

Linear infers that it;s not a "Switchmode" or Switcher" that ntetrupts .
While they are rather wasteful of power they're sure handy for small low power projects..

 

[HomeExperiement]

Ok, looks like I got to tell you honestly all my plans. I have 520W PSU to power 12V led stripes. I wanted to have a way to adjust their brightness. But dimmers cause flickering which defeats the purpose of LED. That's why I was wondering if it was possible to build some component out of something that doesn't cause interrupts? Other reason for asking was just out of curiosity to know how it's done. Even if someone did give me some link to working component that I could just go and buy I would still have wanted to learn how it works.

As I heard before and now from Borek also

capacitor (or coil) that removes the ripples

I also wanted to know how this idea works. And how is is capacitor to be connected in such case.

 

[Borek]

If the frequency of switching is high enough flickering is not visible.

 

[GrahamN-UK]

Ok, looks like I got to tell you honestly all my plans. I have 520W PSU to power 12V led stripes. I wanted to have a way to adjust their brightness. But dimmers cause flickering which defeats the purpose of LED. That's why I was wondering if it was possible to build some component out of something that doesn't cause interrupts? Other reason for asking was just out of curiosity to know how it's done. Even if someone did give me some link to working component that I could just go and buy I would still have wanted to learn how it works.

Do you actually have 520 W of LED lighting to control or do you just mean you have a surplus 520 W PSU, perhaps from a PC, that you want to re-use with some LED lights? What is the power rating of your LED strips?

You can get LED driver modules that connect to the mains (without using a spare PSU) and then either have a dimming function built-in or connect to the output of a low-power dimmer switch. These are examples of each sort:

https://www.amazon.com/dp/B07GXWF63K/?tag=pfamazon01-20
https://www.amazon.com/dp/B075ZBN6X5/?tag=pfamazon01-20

LED driver modules normally do interrupt their output power but they do this so fast you don't notice any flicker. They will vary the duty cycle (fraction of time the output is switched on) to vary the LED brightness. This is a form of pulse-width modulation (PWM).

As your enthusiasm seems to outrun your electronics knowledge I think you would get better results, and use less of our time, if you outlined your top-level wish and let us suggest ways of achieving it, rather than asking some detailed question and everyone needing to work backwards to establish your requirements. And if you want to know how something works, just ask the question directly.

 

[jim hardy]

/DIGRESSION ALERT/

If the frequency of switching is high enough flickering is not visible.

Fancy automobiles nowadays use switched LED's for taillights.
I find them stressful and dangerous when driving at night..
That's because parts of our retina that report peripheral vision are faster than the center where we see in great detail.
When looking straight ahead with my eyes not moving the flickering is not visible.
When i sweep my eyes to one side or the other, as you should do when driving to keep situational awareness,
the flickering makes a series of flashes across my field of vision
and that gives the alarming impression of something incoming very fast.

I find that disconcerting - does anyone else?

As many decades as I've dreamed of owning a '56 Fleewood , I now hate modern Cadillacs for their alarming taillights

/END DIGRESSION/

If these"LED Stripes" are for a car i hope you'll test them at night with your own peripheral vision.

How much current do they consume?
A handful of simple linear regulators might be a very good solution on several counts.

 

[Rive]

I have 520W PSU to power 12V led stripes. I wanted to have a way to adjust their brightness. But dimmers cause flickering which defeats the purpose of LED.

Your problems are a bit more complicated than just that. LED (strip) drivers usually does not support the usage of external dimmers.
However: LED drivers usually works at a high frequency (50-100kHz, so no flickering can be seen (normally).
Some LED drivers has inbuilt dimmer function, so you can set the brightness without additional components.

What is exactly that 520W PSU you are talking about? What you need is not a general 'PSU' but a LED driver.

 

[Borek]

Fancy automobiles nowadays use switched LED's for taillights.
I find them stressful and dangerous when driving at night..

Yes, I have seen that. No idea what frequency they use, apparently too low one. Just a few weeks ago I did some experiments dimming strong white LED with a PWM in kHz range and it looked rock stable.

 

[HomeExperiement]

Hello!

Have been away for a while. Right now have 520W PC PSU. Took it because it was for 1/3 of price of LED power supply. My goal was to achieve flicker free dimming by reducing the voltages. At the time of creating this post I wanted to achieve it by lowering the volts. At my local hardware store I was told that step down modules also work by generating interrupts. And then I came here to learn how to I could build a step down module that doesn't use interrupts.

 

[CWatters]

This isn't really the best place to come and learn the electronic design skills needed to do this project safely.

Does your power supply have an adjustable output? You might only need to reduce the voltage to say 11V to dim the LEDs significantly. That's because they might be made from groups of 3 LEDs and a resistor.

Your best bet is probably to sell the power supply you have and try and find one one that is designed to dim 12V LED strings. Not all LED drivers will do that.

 

[Baluncore]

Here is a circuit that efficiently regulates LED brightness without producing an on/off strobe. It works as a switching regulator, but it regulates the current through D2, the LED, not the voltage.
How it works; Continuous current through the LED, L1 and R1 flows either through N-channel mosfet M1, or through the flyback diode D1.
The LED current is set by the value of R1. As LED current rises, voltage across R1 increases, PNP Q1 conducts more, which raises the voltage Thrs, which turns of the NE555 output and so M1. The flywheel diode then conducts while L1 current reduces, until the Trig voltage falls, turning the NE555 and M1 back on.
When Trig and Thrs are tied together, the voltage ramps between 1/3 and 2/3 of Vcc. Here R3 and R4 reduce that to only about 700mV, which reduces the LED ripple current to about 3 mA.
R5 should be closer to 47R to limit gate current from the NE555 to about 200mA. Vcc noise on CV is reduced by C1.

 

[CWatters]

Don't think that will work if he has 12V LED strips which are normally made from groups of 3 LEDs and dropping resistors?

 

[Baluncore]

Don't think that will work if he has 12V LED strips which are normally made from groups of 3 LEDs and dropping resistors?

It will work as a current regulator to a 12V LED strip.
The resistors will balance the current to the groups of LEDs.
To get full brightness from a 12V strip you will need to raise the Vcc supply voltage to 15V.