Help on my Electronic Project Deployment

Using Arduino Project Guidance
1

Hi,
I have a question and I am not an expert in electronics whatsoever so I am seeking guidance.

I have created my project and now I wanted to deploy it.

Schematic
Schematic960×540 215 KB

I have the following components:

  • 12V Bench Power Supply
  • LM2596 Step Down Buck converter
  • ESP32
  • 12V 8 Channel Relay

Since what I have bought is a 12V channel relay, is it correct that I can power my relay coil directly from my bench power supply? I will remove the jumper cap and connect the JD-VCC and Ground to my 12V bench power supply.

To power my ESP32, I bought an LM2596 step-down converter since I would be powering my ESP32 thru the VIn and isolating it from my Relay power.

Then the 5V step-down voltage is what I would input to the VCC and GND of my relay. The GPIO pins of my ESP32 will be connected to the In1, In2, In3, etc of my relay?

If I am powering a solenoid door lock, valve, or anything that uses a motor. Is it still a requirement to connect a flyback diode to the NO/NC pins of my circuit?

Is what I am thinking feasible?

I tried to draw what I am thinking but if something is not clear. Let me know, please.
I am no expert in Electronics so I am all ears to all suggestions.

Thank you.

2

Yes and no. The diode or a snubber is required and should be connected to the load, not to the contacts.

Correct wiring depends on the module type. See the relay module data sheet. I guess that connecting Vcc is not required.

3

If that is the typical opto-coupled relay module, with the JD VCC jumper, the connection from the ESP32 to the relay board would only need the GPIO pin and 3.3V, wiring 5V to the relay board would over-voltage the GPIO pin, and the GND is not needed because the ESP32 only drives an LED.

4

What then would form an electric circuit? Driving a LED requires two wires, as with any other item.

5

The LED in the opto-coupler is connected to the Vcc of the ESP32 through a resistor, the GPIO pin drives the LED when it is LOW, no different from any other LED.

6

This won't work reliably with a 5 V relay module.

7

Wow, this is really interesting. I tried it now and it really works. So the GND from my 12V bench power supply is not connected to the GND in my ESP32 but it still works.
Amazing! I actually read a lot of posts about connecting the GND of both the external power supply and the ESP32 GND.

An example is from this How to hook up a 12V Relay Module? - #5 by ocuser

I am using the typical Chinese brand of relay which I often see from AliExpress. I noticed that it contains a DS1 component which I think is a flyback diode for the external load if I am not mistaken. I could not find the datasheet for this.

Just to follow up, is the LM2596 step-down converter still needed to power my ESP32?
I have read somewhere that ESP32 can be powered with an external supply of 5v to 12v. So I am thinking if stepping down my 12V bench power supply output to 5V is still needed or if are there any added benefits.

Thanks to both of you! I am learning a lot.

8

Hi, @neluser

@neluser Write some code that JUST operates the relays and find out...
EXPERIMENT.....

Post some images of your project so we can see your component layout.
Can we please have a circuit diagram?

An image of a hand drawn schematic will be fine, include ALL power supplies, component names and pin labels.

Thanks.. Tom... :smiley: :+1: :coffee: :australia:

9

Flyback yes, but for the relay coil only.

10

Ohhh so the Diode in the Relay module is only for the flyback of the relay coil?

So if I am driving a solenoid door lock or valve then I need to add a flyback diode across both loads? Is this correct?

11

Yes, because they are both inductive loads and produce a back emf, many times the supply voltage when turned off.

Tom.. :smiley: :+1: :coffee: :australia:

12

Ok, I will do this once I do more tests. I got excited by David's answer as this is different from what I have read on the internet so far.

13

Hi,

I have a 12V DC solenoid door lock (16 of them in total) and I am controlling it using a 16-channel relay.
Note: I have drawn only 2 solenoid door lock there so that the image is not confusing but there should be 16. I have hidden the Arduino as I have figured out how to control a relay from it already.

16 Channel Relay to Load
16 Channel Relay to Load960×540 152 KB

I have these components that I am planning to wire up.

  • Variable Bench Power Supply
  • LM2596 Step Down DC/DC Converter
  • 16 Channel Relay
  • 16 Door Lock
  • 16 1N4007 Flyback diode

I have two questions:

1. First Question:

I am planning on feeding the bench power supply output to an LM2596 DC/DC Step down converter so that I could get a 12V fixed output.

I am just confused if my wiring above is correct. So If I have 16 solenoid locks I would wire them into the single LM2596 Step down converter output? And will my converter be able to support all 16 of them? The ratio would be 1 to 16.

Or should I have 16 LM2596 converters for each solenoid for a 1 to 1 ratio?

I am confused as I am just a beginner in electronics and I don't know what is the proper layout.

I have been reading a lot of posts about how to control the relay from Arduino but I am able to do it now. But I am not seeing what is the proper way of wiring loads.

2. Second Question:
Is my flyback diode placement correct for each solenoid door lock and is 1N4007 diode okay for my solenoid door lock?

14

Check the LM2596 datasheet for its capacity of delivering current. Do the same for the solenoids, how much current they use. Compare.
Make sure the bench top supply has the needed capacity of current, and voltage.

Flybacks are good.

15

Hello,
Thanks for taking a look. I check the data from AliExpress but I cannot 100% say about its accuracy. These are from generic Chinese companies I supposed.

Bench Power Supply:
Voltage: 0 - 30V
Rated Current: 10A

Solenoid Door Lock:
Voltage: 12V DC
Rated Current: 500mA

LM2596 DC-DC Converter
Input voltage:3V-40V
Output voltage:1.3V-35V
Output current:Rated current is 2A,maximum 3A(Additional heatsink is required)

Let us assume for a moment that this is correct so what should be the proper wiring of the solenoid door lock and the proper computation?

Thank you.

16

Why don't you just set your bench power supply to 12V and eliminate the LM2596?

17

HI,
How long with the door locks be activated?
How many at one time will be activated?

Thanks... Tom.. :smiley: :+1: :coffee: :australia:

18

That looks good but regard the replies from @jim-p and @TomGeorge.

19

I worry about the bench power supply being changed for some reason making it exceed the 12V max limit for the solenoid since it is adjustable. Or I could just be imagining things or being overcareful?

You're right, Hmm have not thought about it but I think they won't be all on at the same time. Let us say if it is half of the time like 8 out of 16 or less.

This is good I am having some clues about your answer but I want to hear it from the experts.
Thank you.

20

@neluser

Your two or more topics on the same or similar subject have been merged.

Please do not duplicate your questions as doing so wastes the time and effort of the volunteers trying to help you as they are then answering the same thing in different places.

Please create one topic only for your question and choose the forum category carefully. If you have multiple questions about the same project then please ask your questions in the one topic as the answers to one question provide useful context for the others, and also you won’t have to keep explaining your project repeatedly.

Repeated duplicate posting could result in a temporary or permanent ban from the forum.

Could you take a few moments to Learn How To Use The Forum

It will help you get the best out of the forum in the future.

Thank you.

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