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I know there is a lot of charlieplexing tutorials out there but non of them are very suitable for my case. I want to charlieplex 4 ledstrips together and control them by an arduino. This means that i need a seperate powersupply and use some mosfets to control the inputs. However I can't think of a way to implement that in my current scheme. I'm very new to all this so I could just not know something that is possible so that's why I'm asking here. Schematic

Does anyone know a way to do this? Thanks in advance, Stijn

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    \$\begingroup\$ that sure is a messy schematic ... very annoying ... why do you need to use charlieplexing? ... you have more than enough pins on the controller chip. \$\endgroup\$ – jsotola Dec 7 '17 at 20:35
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    \$\begingroup\$ Charlie plexing is unlikely to work with more than single bare diodes based on the voltage required alone. \$\endgroup\$ – Passerby Dec 7 '17 at 20:37
  • \$\begingroup\$ You do realize you are using 4 outputs to control 4 strips right? If this is for educational purposes you should be trying single LEDs with resistors. \$\endgroup\$ – Wesley Lee Dec 7 '17 at 20:38
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    \$\begingroup\$ @Passerby I'm sorry but what exactly do you mean? The external powersupply is 12V and 12A that should be enough right? \$\endgroup\$ – Stijn Nowee Dec 7 '17 at 20:54
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    \$\begingroup\$ You cannot directly drive LED strips with the pins. (Unless they are 5V and no more than a few tens of mA) \$\endgroup\$ – Wesley Lee Dec 7 '17 at 20:54
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Charlieplexing relies on the ability of a microcontroller to drive its pins high, low or tristate. In order to do the same thing at 12V, you'll need a bunch of half-bridge drivers, each controlled by two pins on the µC.

It also requires the LEDs (strips, in your case) to be able to withstand the supply voltage applied in reverse, something that single LEDs can easily do at 5V or less. You'll probably have to add a silicon diode in series with each of your strips.

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A deleted answer had a very clever idea. @syd suggested using opto-isolators. The transistor side of the op to would be used to drive the transistor or mosfets needed for the led strips, while the led side of the opto would be driven like a normal charlie-plex circuit would be.

Absolutely no reason the led in an opto can't be charlie-plex like any other led.

The only concern with that is ensuring the voltage and current requirements for the optos, as well as the speed that you need to switch the circuit for proper light output at your strips. This is a unique idea but requires testing.

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