08-23-2016, 06:57 AM
There is another little chip that you can look into -- the 4N35.
... the 4N35 is a optical coupled transistor. Similar to a driver transistor; but, instead of having the signal from the PineA64 touch the gate directly (whether junction or fet) the PineA64 pin only activates an internal LED. The light from the LED optically triggers the transistor internally so that there is an effective isolation between what is being driven (whatever the load) and the driver-- the Pine board.
But, just as pfeerick has stated, if the optical isolator (4N35) is not protected by a diode while driving a coil (inductive load) then back EMF can destroy the optical coupler !
I have used the 4N35 frequently; its a cool little device, and very inexpensive; almost as inexpensive as a regular 2N2222 transistor.
... the 4N35 is a optical coupled transistor. Similar to a driver transistor; but, instead of having the signal from the PineA64 touch the gate directly (whether junction or fet) the PineA64 pin only activates an internal LED. The light from the LED optically triggers the transistor internally so that there is an effective isolation between what is being driven (whatever the load) and the driver-- the Pine board.
But, just as pfeerick has stated, if the optical isolator (4N35) is not protected by a diode while driving a coil (inductive load) then back EMF can destroy the optical coupler !
I have used the 4N35 frequently; its a cool little device, and very inexpensive; almost as inexpensive as a regular 2N2222 transistor.
marcushh777 
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please join us for a chat @ irc.pine64.xyz:6667 or ssl irc.pine64.xyz:6697
( I regret that I am not able to respond to personal messages; let's meet on irc! )