r/arduino • u/Grand-Ad7769 • 7d ago

Need Help on Multiplexed Circuit

I'm building a circuit to drive an 8×8 grid of 64 solenoids, where each solenoid needs to be individually controllable in both polarities (forward current, reverse current, or off).

My current plan is to use a multiplexed H-bridge matrix — 8 H-bridges driving the rows and 8 driving the columns — controlled by an Arduino. I'm planning to use 8 L293D ICs (each has 2 H-bridges, so 8 chips gives me the 16 I need).

My questions are:

  1. Will this approach work as intended?
  2. Are there any issues with using the L293D for this?
  3. Is there a better way to do this overall?
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2

u/Grand-Ad7769 6d ago

Update: I plan to use 16 h-bridge circuits (8 row, 8 column) and control them with shift registers (so I only need 6 pins on my microcontroller)

1

u/ripred3 My other dev board is a Porsche 7d ago

that should work. you will be dealing with the same currents and possible issues that come with other high current inductive actuators like the coils in motors. Pretty much the same thing. Depending on what the current use is at the voltage you need to drive them the L293 may or may not be enough. I would probably take the same or similar path *if* I already had a lot of L293's in my parts bin.

If you haven't bought the drivers yet you might consider using DRV8833's. I'm really starting to like them since they 1) Use power MOSFET's instead of BJT's, and 2) They operate off of a single power source!

https://www.ti.com/lit/ds/symlink/drv8833.pdf

2

u/Grand-Ad7769 7d ago

Thanks for the recommendation! These solenoid don't draw a lot (10-100 mA depending on the voltage). Do you think the L293 will still work for this?

1

u/ripred3 My other dev board is a Porsche 7d ago

yeah they can handle that easily

1

u/Fess_ter_Geek 6d ago

I would consider using four MCP23017 chips for 64 extra digital pins. They work over i2c and you can chain 8 of them together. More if you use an i2c multiplexer chip with them.

Each MCP23017 chip will add 16 pins.

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u/Grand-Ad7769 6d ago

would this allow for current direction to be swapped?

1

u/Fess_ter_Geek 6d ago

I think I misunderstood your plan... I thought you needed 64 pins to signal on or off to a solenoid board and were going to use arduino pins in a matrix.

1

u/Infamous-Amphibian-6 6d ago

DRV8871 drivers are way more efficient, compact and stable than L293Ds, in case you decide to go that way. In any case I’d suggest building on esp32 control.

1

u/nixiebunny 6d ago

You will not be able to drive more than one solenoid at a time. Is that acceptable? 

1

u/Grand-Ad7769 6d ago

Yes that is fine. Controlling multiple at once would be nice but it might be too complex for me.

1

u/HoldOnforDearLove 5d ago

I once built something like this with an addressable LED strip. (Sounds crazy I know) You could scale up to thousands.

The solenoids were powered by switch modules (4 switches a piece) optically controlled by the light strip. The solenoids drew a lot of power at 24v and we're galvanically insulated from the logical part of the circuit. (Emf can affect the microcontroller).

The image shows one of the switch modules and the solenoid it's controlling. It's worked great for 4 years now. Can you tell what the application is?

0

u/adderalpowered 7d ago

Have you thought about these?