external power supply and step up drive the circuit crazy

How about friends, as the title says, when feeding with a pc source my circuit (arduino uno, mg996r servo and ultrasonic sensor) works correctly, the intensity of the LEDs drops a bit when turning the servo but nothing bad, the problem is that if I want to use a step up source (mt3068 or xl6009) the arduino board, the sensor and the servo go crazy, they start to work super bad, the truth is that I ruled out that it was a problem of the source since I tried 2 different models and I got the same results, from the PC supply I turned on the Arduino and the others competent with 5v 16A and it works correctly, but adding a source step to raise the voltage to 6v / 7v starts to work terrible, I even tried to leave the same voltage output than input and nothing, it keeps malfunctioning. Anyway friends I hope you have understood me and thank you in advance.

That explanation in words is crying out for some circuit diagrams please.

Yes. What is source step up? Is this source supplying enough current? Where are you applying it, 5V or Vin?

Anyway friends I hope you have understood me

Sorry but no. Very difficult to make any sense of it.

works correctly, the intensity of the LEDs drops a bit when turning the servo but nothing bad,

No this is bad, it shows that you do not have enough current capacity and supply decoupling.

By step up do you mean this?

If so these are crap and will not supply very much current. In my tests I couldn’t get more that half an amp out of them. The current drops the higher you want to step it up from the origional voltage.

Again you fault descriptions smacks of insufficient or even no supply decoupling.

here is the circuit, for friends who did not understand, my problem is that I need between 6v and 8v approximately so that the circuit works correctly, if I feed it with 5v it works well and it hardly decreases the intensity of the arduino's LEDs when the servo is on progress, but when I use a boost source to increase the voltage like a mt3608 or xl6009 the whole circuit starts to fail and I don't understand why if I am increasing the voltage, I tried regulating at 5.5v, 6.0v, 7.0v, 8.0v and the circuit keeps failing all the time.

Pd:(I forgot to connect the negative of the servo in the diagram).

Ok I told you this before but one more time.
You can not get 7V @ 3A from that converter, despite what they say in the advert it simply will not deliver this.

You have no decoupling capacitors in the circuit so even if you had the current capability the supply would be unstable.

Feeding 7V into the 5V pin of an Arduino will kill it.

my problem is that I need between 6v and 8v approximately so that the circuit works correctly

No you don’t and even if you did it wouldn’t work because the Arduino would malfunction.

Ask all you like but the answer is you are doing it wrong.

Just hook the PC PSU straight to the UNO. If the LED still drops in brightness you have a big problem.

Grumpy_Mike:
Feeding 7V into the 5V pin of an Arduino will kill it.

sorry I was wrong in the diagram, I feed the arduino from the Vin, not from the 5v, I was wrong.
Well friend, you say that the module will not deliver those 7v 3A, but why then did I regulate the voltage to 7v or more if I want it? What you want to tell me is that it does not supply the amperage that it should supply? How could I feed the circuit then? because obviously I'm not going to always feed it with a pc source. Thanks in advance

Assuming you have a power supply that can provide the current that servo requires, can a breadboard power rail sustain that kind of current?

I may be wrong but afaik breadboards are more suited to signal levels of current, not motor power.

windoze_killa:
Just hook the PC PSU straight to the UNO. If the LED still drops in brightness you have a big problem.

Indeed I do that and it works normal, the problem is that I need a more specific voltage than the source can give me, I need between 6v and 8v, and for that I use the step up module but apparently it does not do its job normally

fionning_macara:
Suponiendo que tenga una fuente de alimentación que pueda proporcionar la corriente que requiera el servo, ¿puede un riel de alimentación de placa sostener ese tipo de corriente?

As seen in the diagram, I feed the servo and the board separately, the only wire from the servo going to the board is the signal wire

My point was that you have the power supply at one end, and the servo at the other, so whatever the servo is drawing is being delivered through the breadboard power rail, and I'm not sure it's designed for that.

you say that the module will not deliver those 7v 3A, but why then did I regulate the voltage to 7v or more if I want it? What you want to tell me is that it does not supply the amperage that it should supply? How could I feed the circuit then? because obviously I'm not going to always feed it with a pc source

Yes it will supply 7V but not at 3 amps because it is a piece of crap. I told you this, I never said it would not generate 7V. If you want to use 7V @ 3 Amps then you have to use a step up board that will work.
These normally cost a lot more that the crap board you got.

If you have a 5V supply connect direct to the Arduino’s 5V pin. Then set your board to 6.5V and drive the servo with this. Drive the distance sensor from the same 5V you use to power the Arduino. Then you need something like a 1000uF capacitor across the servo’s power.

Do not power the servo with more than 6.5V unless it says so in the spec. You can run a servo happily off 5V, it is just that it has less torque.

Grumpy_Mike:
Do not power the servo with more than 6.5V unless it says so in the spec. You can run a servo happily off 5V, it is just that it has less torque.

Exactly. I can't see the problem. Unless there is another part he is not showing.

Are there, btw, any guidelines for maximum current through a breadboard before the tracks vapourise?

fionning_macara:
Are there, btw, any guidelines for maximum current through a breadboard before the tracks vapourise?

Way before that happens the resistance in the connectors will produce an unacceptable voltage drop. Normally anything approaching one Amp is considered too much.

Like all things in electronics there is no single point when something stops working, it is a continuum. A lot depends on the specifics of what you are trying to do.

fionning_macara:
Are there, btw, any guidelines for maximum current through a breadboard before the tracks vapourise?

Yep. Wait till it happens then wind it back a bit.

Grumpy_Mike:
Way before that happens the resistance in the connectors will produce an unacceptable voltage drop. Normally anything approaching one Amp is considered too much.

Unless you have a really old one like mine that is ratedat 5A.

The connecting bars might be rated at 5A but the resistance at the point of contact between the component and the bar will mean you won’t get that current in practice.

Grumpy_Mike:
The connecting bars might be rated at 5A but the resistance at the point of contact between the component and the bar will mean you won’t get that current in practice.

…and the huge variation in lead types that contact the bars, also makes the safe maximum current more difficult to predict.