the sainsmarts. seems textbook advice use external power...but between youtube tutorials , i've got couple 2 channels relay boards have worked flawlessy giving them 5v gpio vcc , jdvcc, driving pins low trigger relay coil. seem i'm putting 5v pi when drop pins low, far good. need 8 channel , more concerned voltage current though tutorials show hooked same. - textbook aside: has damaged pi this? or evidence against doing merely theoretical? or misunderstand altogether?
when pi gpio output low, problem current not voltage. limited safe value long sainsmart has opto-isolated input (some do, can't know models).
difficulty when gpio output high. sits @ 3v3, connected through opto-isolator 5v. far harder show safe (current flowing in gpio protection diodes). not every relay board see high (off) input.
time ago here did experiments seemed show 1 particular pi safe use way (i don't remember experimental details. think she(?) got fed being told wasn't idea , stopped posting.
no, not aware of evidence pi has been damaged. aware of anecdotal evidence pis survive. is, however, outside recommended (specified?) operating conditions. if pi damaged, don't complain, don't try , claim under warranty, , post here can build evidence.
difficulty when gpio output high. sits @ 3v3, connected through opto-isolator 5v. far harder show safe (current flowing in gpio protection diodes). not every relay board see high (off) input.
time ago here did experiments seemed show 1 particular pi safe use way (i don't remember experimental details. think she(?) got fed being told wasn't idea , stopped posting.
no, not aware of evidence pi has been damaged. aware of anecdotal evidence pis survive. is, however, outside recommended (specified?) operating conditions. if pi damaged, don't complain, don't try , claim under warranty, , post here can build evidence.
raspberrypi
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