Can overheat an AC device

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AC device also with direct current?

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Hello! I have an electrical device that needs low AC current at the input, but has an internal rectifier. Now the question ... a rectifier flattens the alternating current anyway ... can I go in to the AC input with DC? It is 10 volts and not high voltage. Thanks...

Answer 1 from Yeah

Answer 2 from PcDock


1. But that is possible, just pay attention to correct polarity.

2. The input voltage must be a little higher ~ 14 V.

3. Simply testing, nothing can happen.


Hardware lives and is independent

Answer 3 from Yeah


pcdock - this is maybe an isolated case?!: there is more than one way to construct a rectifier ...

with a simple gr├Ąz circuit it would work - but why increase the voltage?

With an OPV (operational amplifier), however, it will not work - and with the increased voltage he will shoot the IC to pieces ...

Answer 4 from PcDock

@Yes / Yes,

1. if you are so sure about that. :)

2. "internally, however, has a rectifier." ---> and I gave an answer to this.!

3. Answering it with "no" in principle is just as wrong. !!
So much for your "um."


Hardware lives and is independent

Answer 5 from Elefunty

is it a normal rectifier circuit with 4 diodes ??
is anything "tapped" in front of the match judge? So any buteil in front of the rectifier (no safety)? whom yes which


Answer 6 from JoMeister

So there is a device with a microcontroller in it, which sends signals to other devices via an interface.

The device core works with direct current. Since this device was not produced in Germany, it was designed in such a way that you go in with alternating current and not with DC, as is usual here.

The rectifier is located on the motherboard using SMD technology and, with my limited knowledge and equipment, I cannot handle it - and it cannot be categorized in any way as to which type it is.

I only have the two strings to which a 230V built-in power supply was previously connected and which I removed for the purpose of modifications. There was no tap in front of the rectifier, so there is no component that depends on alternating current ...

Is that the information you need?

Answer 7 from Yeah

@ PcDock

To answer it with "no" in principle is just as wrong. !!

..but at least not as dangerous as your suggestion, just give it a try and increase the voltage right away - so that in case of doubt it just breaks? then the problem is also solved ... true. ;)

well - whatever ..

@ JoMeister

I only have one time to take a picture and make us available.

I think there will be someone who has a solution for it or who recognizes the component ...

Answer 8 from PcDock

@Yes / Yes ,

1. What is your problem?

2. Have you overlooked that there are at least 2 diodes in series?

3. And as you argue here, I assume you know what happens then.

So that's it for me on this topic.

@ JoMeister,

1. Forget everything I wrote here.


Hardware lives and is independent

Answer 9 from Yeah

1. What is your problem?

I don't have any - just wanted to object that he can also shoot the device with the help of your tip. at least that it doesn't necessarily work:

see "1. But this is possible, just pay attention to correct polarity."

2. Have you overlooked that there are at least 2 diodes in series?

Huh? when where? Yes and? do I really have to read over ... do you mean a bridge circuit? yes it can be that he has such a simple circuit. I also wrote that it can work then, but you don't have to increase the tension right away, right?

but even IF he has such a circuit, there will still be a smoothing afterwards, since the microcontroller certainly can't do anything with the coarse half-waves.

And we don't know how THIS smoothing is implemented either.

So that's already 2 assemblies (possibly combined in one IC) of which we don't know how they react to direct current at the input!

just let you through a little about rectifiers and smoothing ... maybe you will also notice that not all circuits react in the same way and that your answer was simply dangerous at times (my opinion).

so I don't want to annoy you or have any other "problem" ...

Answer 10 from Friedel

It is very likely that the device contains either a bridge rectifier with subsequent smoothing. In this case you can connect DC voltage. The polarity does not matter. The DC voltage must be slightly higher than the peak voltage of the AC voltage that was previously connected. If 10 V AC voltage was previously connected, the peak voltage was 10 V times the root 2 = approx. 14V. So you have to connect a little less than 14V DC voltage. You could try 12V from a car battery or something similar.

But it can be that another circuit is built in and that you destroy the whole thing.

Even if there is such a circuit, it is not unlikely that you will destroy the device in the process. With AC voltage, the current always flows alternately through 2 of the 4 rectifier diodes. With DC voltage, it then flows permanently through the same two diodes, while the other two are not used. With SMD components, there is a great risk that the two constantly loaded diodes will overheat.

According to your little information, it could be a very valuable device. In that case I would prefer to generate an alternating voltage of 10V with a simple resonant circuit. A square wave voltage is sufficient. For example the astable multivibrator at or something similar are easy to tinker with and solve the problem. In general, the IC 555 can often help you in a country without AC voltage.

Answer 11 from Yeah

[...] the IC 555 often help [...]

hihi. have a little "mosaic" booklet from the GDR times: "all-rounder 555" ...

I didn't think that someone would do something with it. So if you need something, I'll be happy to scan a few pages for you ...

Answer 12 from Snoopie

I am wondering a little ...

There was talk of an expanded 230V power supply. And why is DC needed when we have AC 230 V here, so the aforementioned power supply would be exactly the right thing?

And when it comes to such a complex device with a microcontroller, etc., more than one DC voltage may be required, perhaps even with a different polarity. It will certainly not be enough to offer the device DC instead of AC.

I would keep my hands off such activities and operate the device in its original state on 230 V AC.


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