arduino promini 3.3V , out put digital.

[Reza]

hi
if i want use a arduino promini 3.3V for relay , so there is a question!
the digital output of arduino for relay input (5V relay) is 3.3V !?!?! can this voltag trigger my relay input ?

[sundberg84]

@Reza with a 5v relay and without any step-up to 5v - most likley no.

[TheoL]

@sundberg84 Would a logical level converter help? I want to do the same in the near future.

[m26872]

@TheoL A transistor would do just as good as a level converter since it's only one direction, but nevertheless depend on that you'll have 5V available from somewhere.

[Reza]

@m26872 , @sundberg84 , @TheoL :
thank you my friends , so i need increase voltage for digital output

[Mike Musskopf]

Hi @Reza , there's no need to increase the digital output voltage . You just need to have a 5V source somewhere and you can use a N-MOSFET to drive the relay.

It would look like that:

Just ignore the "INPUT" it should be an OUTPUT on the diagram above. Also the MOSFET needs to have a lower VGs and support the current required by your Relay. Something like that should do the trick: http://au.element14.com/on-semiconductor/ntr4501nt1g/n-channel-mosfet-20v-3-2a-sot/dp/1431305.

Just avoid the common mosfets like BS170 and BS250 as they need some high voltage on the Gate to actually let the current flow. The datasheet will always have a few charts showing how much current the mosfet let flow for different VGSs.

Cheers,
Mike M.

[Reza]

@Mike-Musskopf said:

Hi @Reza , there's no need to increase the digital output voltage . You just need to have a 5V source somewhere and you can use a N-MOSFET to drive the relay.

It would look like that:

Just ignore the "INPUT" it should be an OUTPUT on the diagram above. Also the MOSFET needs to have a lower VGs and support the current required by your Relay. Something like that should do the trick: http://au.element14.com/on-semiconductor/ntr4501nt1g/n-channel-mosfet-20v-3-2a-sot/dp/1431305.

Just avoid the common mosfets like BS170 and BS250 as they need some high voltage on the Gate to actually let the current flow. The datasheet will always have a few charts showing how much current the mosfet let flow for different VGSs.

Cheers,
Mike M.

hi
thank you