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I'm using a relay like the one in the picture, controlled by an Arduino. I basically use it for turning mechanically on/off a circuit, when i have 0 as constant output from a series of values that describe a sinewave.

The system does what i expect, but every time that the sinewave cross the 0, it gives an input to the relay.

The input is so short that it doesn't trigger its status... this is perfect for what i want, but i don't know if this stress applied to the relay might brake it in the long run.


right, i should be more precise...

the arduino is comunicating with the DAC of a circuit via SPI. No waves from Arduino itself... it just gives the values to the DAC which then generates the wave.

The entire system have not be designed to be switched on/off by software (i need to automatize the process and save the battery). So, for controlling mechanically the ON/OFF of the circuit i added the relay, connecting it with a digital pin of arduino.

In the arduino firmware i figured out how to turn the relay OFF when the values of the wave are equal to 0 (so there is not real output), this work very well.

The problem is that since the values describe a wave that goes between positive and negative values, the 0 is "touched" for each period of the wave.

Apparently this give no problems, because the relay doesn't turn the circuit off, but i see that one of the LED of the relay module blinks according to the frequency i set, and the relay makes some noise with a pitch that vary also according to the frequency.

The relay is placed between the circuit and a 9V battery, so no much current going on there, but I don't know if this stress might brake the relay.

Here an approximate schematic... if it can help...

enter image description here

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  • \$\begingroup\$ You need to be more precise in the description. "does not trigger its status" and "partial activation" are not exactly the same \$\endgroup\$ – Maple Aug 16 '18 at 22:14
  • \$\begingroup\$ I don't imagine it can be a good thing. If it's Arduino controlled then why not change the software so it doesn't do that? \$\endgroup\$ – user253751 Aug 16 '18 at 22:24
  • \$\begingroup\$ @immibis indeed my problem is to modify the software to make it work perfectly \$\endgroup\$ – pat Aug 16 '18 at 23:04
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Relays of this size have an operating time of 10 ms and a release time of 5ms.

Since a reasonable zero-crossing interval does not have enough time to make the contacts close. The interval of 10 ms is max which means it can start to move at 100,120 Hz zero crossing pulses, but the result ought to be null for < 100us. (estimate)

The coil energy is negligible compared to steady On. Thus no arc energy occurs across the contacts (from reactive loads) .

If however, it makes a loud buzz, there may be mechanical wear after 10 million cycles which is a common rating for mechanical full cycles.

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I'm using a relay like the one in the picture, controlled by an Arduino.

They are designed to receive

  • 5 V power on the Vcc pin,
  • 0 V or GND on the GND pin,
  • the module in your picture explains that an input of between 0 and 1.2 V will turn the relay on (and implies that any voltage above 1.2 V will turn it off) meaning that it is "active low".

The module is intended to be driven by a digital output off/on, low/high, 0V/5V. It is not intended to be used on an analogue output.

I basically use it for turning mechanically on/off a circuit, when i have 0 as constant output from a series of values that describe a sinewave.

The Arduino doesn't have an analog out other than PWM which is fast digital pulse-width modulation which is either fully on or off. The PWM signals are much faster than the relay can respond. The Arduino outputs cannot switch negative so it is not possible to generate a sinewave from it.

Where is your sinewave coming from?

The system does what i expect, ...

What do you expect?

... but every time that the sinewave cross the 0, it gives an input to the relay.

If you really are feeding it a sinewave then this is to be expected.

The input is so short that it doesn't trigger its status... this is perfect for what i want, but i don't know if this stress applied to the relay might brake it in the long run.

The relay might be moving the contacts to the point where the spring pressure is lowered enough to give poor contact and this might cause problems - particularly on high current.

Your question needs a lot more details to be answered properly.

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