Greetings, please see the attached jpg. Allow me to start by saying that the circuit shown on the right works. I have it functioning in two separate devices. Free-wiring another device (no breadboard, insulated wires flying) does not work so well. Even though the leads are 3" or less, the switched SSD1306 actually displays data WITHOUT the vcc wire attached.
I am open to doing this entirely differently if someone has another idea for switching between non-addressable OLED displays. Thank you!
Can you share a datasheet to the display you are using?
What controller ?
Why not use a MOSFET ?
Show us a good schematic of your proposed circuit.
Show us a good image of your ‘actual’ wiring.
Give links to components.
Greetings,
I found this on the Internet. I believe it properly represents my device. Thank you for not being like LarryD. He asks incomplete questions while giving no example and wants me to reveal massive amounts of data not related to my question.
I believe the persistent display when the power is removed is caused by the pumping capacitor. I believe my solution is a capacitor or resistor somewhere in line but I am unable to decipher the technical manual. If you see something I am missing, I would greatly appreciate you throwing me a bone.
Link to a PDF spec. sheet on a typical .91 OLED display
Without knowing what the controller is, we have no way of knowing what voltages we are dealing with and what the logic levels are for your GPIOs.
A MOSFET for HIGH side switching was going to be recommended, however, we don’t know what your hardware experience is.
A schematic shows us your setup and can reveal possible problems that you might be having, at a minimum, this is the best way of showing us what you are doing.
How dare we ask you to reveal massive amounts of data.
Hum, maybe you should have been asked to follow the forum posting rules 
.
Gawd,
Did you not see the schematic attached in the word document? It clearly shows a digital output energizing an opto-coupler by means of a 220 ohm resistor that is, in turn, energizing the vcc of the display module with 3.3vdc. I said that I was using a Seeeduino XAIO (the controller) and I called the output 3.3 vdc. What more could you possibly want or need to help me with this? If I came upon the diagram I included, I could easily build what I provided a schematic for.
I have enough experience to know what a MOSFET is but I feel as though there must be other DIP packages that I could use as a digital switch if my opto-coupler is not working properly. Except, of course, it IS working on my breadboard and prototype as I previously said. THIS is where the smoking gun lies. I do not see the need to switch from an opto-coupler to a MOSFET, I would rather find out why, when my displays have about 3" of I2C wiring running to them, they behave unusually displaying some issue best associated with capacitance.
What I am hoping to find here is someone with experience actually incorporating dual displays activated by control logic.
The passive aggressive posture you exhibit (read: most of your reply) is why I cringe every time I attempt to receive help from this forum. For every helpful, non-judgemental individual, there are three people like you who seem to take great joy in rubbing my face in not doing things the way you would have me do them. As far as I can tell, everything you called me out on is wrong!
I guess I could include the complete schematic for my prototype and, while I am at it, the entire proprietary C++ code that makes it work but I hope you would not consider me so foolish or stupid. I'm just a 63-year-old hack whom you choose to attack because of control issues on your part that I have long since worked out of my psyche. I am going to venture a guess and say that you were a Marine.
We had little to work with, didn’t even know if your display was SPI or I2C.
I have switch power to similar loads many many times over the years including power to displays.
A logic level (3.3v) P MOSFET (High side switch) will probably do what you need.
Schematic to follow.
Was this quote just fluff 
You might want to review the posting guide lines, they can be accessed at the top of every forum.
EDIT, Schematic
Often called "phantom power", the data lines leak current into the display.
Each OLED display needs a separate in uC buffer. To run both displays on the same buffer means you must initialize each display separately immediately after switching them.
A better solution is to buy Adafruit I2C OLED that have a default address and a second address that can be utilized for 2-display projects. Second address requires modest board changes.
SPI OLED displays are more suitable because they can be switched with the chip-select line.
Yes, the SPI display version is the solution to the dilemma.
I couldn't get that link to load for some reason.. could you re-post?
FYI. This is actually the most responsive and helpful forum I have ever come across, and the knowledge that some of the crusty, grumpy, pedantic, old dudes on here should not be underestimated or undervalued. If you look between the banter you will find some nuggets. 
Hi Everyone, thanks again for all who have posted a wealth of information. I apologize again for not posting in the way others would have me doing. I figured that, with the picture of the display clearly showing only four points of attachment, more adept minds would know what they were seeing. Ultimately, I came across I2C multiplexers this morning but I am going to try using two opto-couplers, one for SDA and one for SCL. This would allow a tinier footprint than an 8-channel multiplexer board.
Forum Solution.pdf (37.3 KB)
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