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I am new to embedded circuits and working on a problem with which I need help.

I am using ESP32 soc for controlling a bistable valve using DRV8833 driver module. Please refer to this link for valve specifications or a quick reference is available with below table. enter image description here

The below block diagram refers to the architecture that I am following. Since I am using a bistable valve, if in between the operation there is a power failure or system damage, it continues to be in the state. Even though I can use a monostable valve, I want to make this much less energy-consuming and battery-operated for the long term. I would like to add a fail-safe circuit to the design which should automatically set the state to default state in case the MCU module fails or the power supply goes.

Note: I have tested the valve to be operated using 4700uf/10v capacitor to change the state and it works.

I want to build the red-colored portion as shown in the image.

enter image description here

can anyone light me with a sample circuit for this logic.

Vyshakh P
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    There are circuit links broken on that website --> [For further details about the latching solenoid valve and its driving circuits click here](https://www.hnhcart.com/blogs/learn/latching-solenoid-valve). A pdf file data sheet is by far the most preferable way of presenting the valve data. – Andy aka Dec 07 '22 at 09:18
  • @Andyaka Sorry for the inconvenience. I have attached the spec here, the pdf datasheet i am still searching for the same valve – Vyshakh P Dec 07 '22 at 10:47

1 Answers1

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Here's the schematic.

enter image description here

When the relay is energised, the capacitor charge pulse sets the bi-stable valve.

When the relay is de-energised or when there is a power failure, the inverted capacitor discharge pulse resets it.

vu2nan
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  • Thanks.. This might work.. looking for a ttl logic circuits for the same to avoid bulkier design, LIked this approach. And this would be as same as using default closed valves, the relay needed to be powered during the operation time and will take more power. – Vyshakh P Dec 07 '22 at 10:30
  • You are most welcome! – vu2nan Dec 07 '22 at 15:55