Looking for advice on attached Fritzing diagram please

[LarryD]

Maybe redraw the relay circuit, see J3:

[jbaich]

also, I'm wondering if I'm a bit confused on the concept of "ground" I always thought this was the negative terminal in DC? (typically, I know it can be other things, but as a generality)

I've attached an image and I'm not sure if there is any difference between the top section and the bottom section... I would have said no, but now I'm not so sure... can someone clarify?

I'm thinking maybe this is where I'm confused leading to the polarity of the centre channel?

Thanks,
Joe

[jbaich]

ok, I feel like an idiot... what's wrong with J3? I don't see what you're referring to...

This one post every 5 minutes rule is killing me!

[LarryD]

Ground:
Most often ground is negative (but there are times it can be positive, beware).
Both drawings are OK.
However, it is recommend the global GND symbol be used.
This reduces the complexity of your drawing by not having to run a ground line all over the schematic.

J3:
Bring your wires into a connector as shown in the J3 image"I" posted in #60, not the way you have it in your original image.

Edit:
Putting a .1uf across the water pump relay contacts wouldn't hurt either as mentioned by YoungSteve.
The relay contact .1uf protects the contacts.
The motor .1uf and1N4007 snuffs out motor electrical noise.

[OldSteve]

jbaich:
Also, just to be clear, you're talking about a capacitor across the relay contacts for the motor, right? so basically just change the diode to a capacitor in the sketch? is .1uf appropriate here as well as for the pump?

No, I was talking about the 12VDC pump. The other motor isn't controlled by a relay. It's controlled by the L298N board, and needs no additional parts at all. This is all getting very confusing.

Just put an 0.1uF cap across the relay contacts to the pump and Bob's your uncle.

I think too many cooks is confusing things, so I'll leave you to it. There's ample help.

[LarryD]

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[jbaich]

LarryD:
Edit:
Putting a .1uf across the water pump relay contacts wouldn't hurt either as mentioned by YoungSteve.
The relay contact .1uf protects the contacts.
The motor .1uf and1N4007 snuffs out motor electrical noise.

Hi Larry, thanks for attaching that diagram, it helped a lot. However now I'm confused by your comments above, when you say motor... are you referring to the pump? I guess they are both just motors? Also in your earlier post (#60), you attached a pic of the portion of the drawing with the reed swtiches, but I'm not sure what you were trying to tell me with that...

I have redrawn the water pump and J3 in a fashion that I think replicates your schematic and have reattached the most current drawing. Is there anything else that stands out? anymore diodes or fuses that I should be putting in to protect things?

As far as the ground question goes... can you ground 9V and 12V together or do you need to keep the grounds separate based on the voltage?

Thanks,
Joe

[LarryD]

Hi Larry, thanks for attaching that diagram, it helped a lot. However now I'm confused by your comments above, when you say motor... are you referring to the pump? Yes I guess they are both just motors? Yes Also in your earlier post (#60), you attached a pic of the portion of the drawing with the reed swtiches, but I'm not sure what you were trying to tell me with that... See the look of the drawing attached now.

I have redrawn the water pump and J3 in a fashion that I think replicates your schematic and have reattached the most current drawing. Is there anything else that stands out? anymore diodes or fuses that I should be putting in to protect things? Make sure your centers on the power jacks are the correct polarities.

As far as the ground question goes... can you ground 9V and 12V together or do you need to keep the grounds separate based on the voltage? Yes

[jbaich]

dlloyd:
Yes, a different 5VDC supply that isn't shared with the supply that powers the Arduino's supply. Also needs to be isolated from the mains. Yes, wall adapters are isolated from the mains and are OK, but I'm not sure about using those ultra miniature USB chargers available at the dollar store or eBay.

So being both electrically separate from the Arduino and the mains is what's required to utilize complete optical isolated control of the relay. There'll be absolutely no conductive path to transmit interference.

Even though opto-isolation resolves conductive interference, emissive interference could also create problems. Solutions for this attempt to dampen the arc-energy across the contacts or inductive energy across the load. Here RC snubber, MOV and Ferrite coil are some arc-suppression techniques. Also, increasing the distance from the Arduino to the Relay board and AC load and wiring helps.

Opto-isolation is most likely all that's needed when switching 120VAC inductive loads. At higher voltages, emissive EMI plays a greater role. Of course, the size of the load also plays a role.

Thanks for this dlloyd...you gave me a lot of info here, most of it went over my head, but I've been researching to try and figure it out and come up a bit short on the following questions...

1. If the 120V AC receptacle that supplies power to the 5V DC wall adapter (which would be the supply for the relay module), also supplies power for the 120V AC devices that the module is controlling... AND supplies the 9V DC adapter for the Arduino... is this electrically separate? or are you saying that I would need to supply the 5V DC adapter for the relay module from a completely different 120V AC circuit?

If so, that could be problematic given the ultimate location of this project out in the yard...

2. Would a 5V adapter such as this be a good choice? does the built in noise filter have any benefit in this application?

http://www.amazon.com/CanaKit-Raspberry-Supply-Adapter-Charger/dp/B00MARDJZ4/ref=pd_sim_147_5?ie=UTF8&dpID=51KgJwxynLL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=09JZ3N8E3WWG4F7WGADX

3. When you say increasing the distance between components may help, are we talking a scale in feet or inches or yards?

Thanks,
Joe

[jbaich]

LarryD:
I have redrawn the water pump and J3 in a fashion that I think replicates your schematic and have reattached the most current drawing. Is there anything else that stands out? anymore diodes or fuses that I should be putting in to protect things? Make sure your centers on the power jacks are the correct polarities.

As far as the ground question goes... can you ground 9V and 12V together or do you need to keep the grounds separate based on the voltage? Yes

Thanks for clearing up the capacitor and I'm assuming that you are saying "Yes" to keeping the grounds separate...? "As far as the ground question goes... can you ground 9V and 12V together or do you need to keep the grounds separate based on the voltage?

Thanks,
Joe

[LarryD]

Was have breakfast not paying attention.
Yes, 9V and 12V grounds must be connected since 12V is going to the 298 motor driver.

[jbaich]

Hi Larry, I've attached my drawing again with 3 areas highlighted and questions in speech bubbles, which are;

1. The ground pins on the Arduino are locations to ground things like sensors and reed switches, correct? So I could just draw (and eventually actually physically connect) the lines from the ground terminals on the sensors and switches to these pins on the board?

2. Just want to confirm visually about tying the 12V and 9V negative (ground) wires together...

3. Does my drawing indicate the polarity of the centre is negative? if so, what am I doing that is indicating this... all centres should be positive? is it the tiny lighting bolt on the supply symbols that people think looks like a "+" sign?

Thanks,
Joe

[LarryD]

1. The ground pins on the Arduino are locations to ground things like sensors and reed switches, correct? YES So I could just draw (and eventually actually physically connect) the lines from the ground terminals on the sensors and switches to these pins on the board? YES

2. Just want to confirm visually about tying the 12V and 9V negative (ground) wires together... YES

3. Does my drawing indicate the polarity of the centre is negative? YES you do if so, what am I doing that is indicating this... all centres should be positive? See attached image top right hand corner is it the tiny lighting bolt on the supply symbols that people think looks like a "+" sign? It is the + an - labeling in the symbol

.

[jbaich]

Well that explains a lot! Thanks, I've switched all the power supply symbols around to indicate positive centre channels.

[LarryD]

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[jbaich]

LarryD:

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Funny, I've just been staring at those relay connections and wondering what the difference is between using 1 vs 2.... I understand normally open vs normally closed, but functionally either way the circuit would not be completed until the arduino signals the relay to pull the switch to terminal 3...? or is that wrong?

Thanks,
Joe

[jbaich]

never mind...
I see it now

[jbaich]

Just a quick question about schematic vs reality... in the attached image, are figure 1 and figure 2 effectively the same thing?

Thanks,
Joe

[CrossRoads]

No. The diode below the motor in figure 2 will not allow any current flow thru the motor.
The diode in figure 1 dissipates motor generated current that is created when the motor stops being driven and the motors magnetic field collapses, which creates current flow.

[LarryD]

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