André06

Most of theses relays are designed to work with 5v power supply and thus have an input  theshold between 0 and 1 somewhere in the middle voltage (2 - 3v). As a GPIO pin of an orange pi works between 0 and 3.3v. Sometime the switching to 1 does"nt wok as the input level is not high enough.
Powering the relay with 3.3v allows to solve the issue as the input  threshold moves down around 1.5v. The drawback is that the mechanical energy to swith the rely is lower and the electrical contact could be affected.
Some of these blue relays have 2 power inputs. The 5v to power the mechanical part and the 3.3v to power the optical isolator at the input. This is the best solution to correctly switch.
 
If you need some info on the GPIO for the Orange Pi One plus , I wrote an article on the subject.
https://f1atb.fr/index.php/2020/06/16/gpio-on-orange-pi-one-plus/
 
Regards
Ham radio F1ATB
André
 
 
 

Most of theses relays are designed to work with 5v power supply and thus have an input  theshold between 0 and 1 somewhere in the middle voltage (2 - 3v). As a GPIO pin of an orange pi works between 0 and 3.3v. Sometime the switching to 1 does"nt wok as the input level is not high enough.
Powering the relay with 3.3v allows to solve the issue as the input  threshold moves down around 1.5v. The drawback is that the mechanical energy to swith the rely is lower and the electrical contact could be affected.
Some of these blue relays have 2 power inputs. The 5v to power the mechanical part and the 3.3v to power the optical isolator at the input. This is the best solution to correctly switch.
 
If you need some info on the GPIO for the Orange Pi One plus , I wrote an article on the subject.
https://f1atb.fr/index.php/2020/06/16/gpio-on-orange-pi-one-plus/
 
Regards
Ham radio F1ATB
André