I'm completely new to this and trying to plan what I would think should be a fairly simple project. I'm not worried about coding right now, just actual wiring and connections. "All" I need to do is to run a pump, and use two solenoid valves for switching the input 'line' into the pump
The pump can only run at 6V because that is all the solenoids valves can handle. The solenoids valves are 12v and only one of the two will ever be powered at the same time, so I think I can use a squid to split the power supply for them.
I think I could probably use a relay shield rather than the 3 relays, but I used three for simplicity in the drawing... I really have no background with this, and the tutorials all seem either too high level or too low level to be helpful to me at this point. So if someone could take a look at the crappy drawing I put together and tell me if at least on the right track and provide suggestions, it would be greatly appreciated.
First DC is direct current like the current from a battery.
AC is alternating current like the current in the wall socket.
On all DC devices that have a coil of wire like a: 12 volt pump, or motor, or relay or solonoid.
Install a diode across the terminals of that device.
The side of the diode that has a painted bad is the cathode.
The cathode side goes to the coil wire that is connected to the positive of the power supply.
The other side "anode" goes to the other coil wire.
The reason they are telling you to use diodes is to protect your microcontroller and other electronics against voltage spikes from when the solenoid, pump, and/or relays shut off. You are actually wiring the diode so that any current back flowing will stay within the coil / diode until dissipated rather than back-feeding through your electronics causing the magic smoke to come out.
Hopefully that makes sense. Although it appears from your drawing you are using some form of relay shields. It's quite possible your relay shields already have this diode protection or opto isolaters and the diodes may not be needed. Do you have specs on the relay parts you are using?
OK.
So, I think I have a chance of understanding now.
the pump and the solenoid need diodes across the coils. I'm really really visual, and not being about to hold these in my hand, or turn them and really look at them is a real stumbling point. These are the links for the pump and the solenoid valve. Can you give me an idea where I should be looking for where I would put the diode? Once I get a picture in my head, I can move to tutorials and the like and have an idea what I'm seeing, because right now I'm kind of grasping... http://www.trossenrobotics.com/solenoid_valve http://www.trossenrobotics.com/p/dc-liquid-pump-medium.aspx
Look at the first image below.
The silver (left side) band of the diode is the cathode.
Secure your solenoids and pump to a surface.
Cut the wires going to each so you can still terminate them with a bit of free slack.
Solder the cathode of a diode to the red pump wire, connect this junction to +6 volts DC.
Solder the anode of this diode to the black pump wire.
Solder the cathode of the second diode to one of the black wires on a solenoid, connect this junction to +12 volts.
Solder the anode of this diode to the other black wire on the solenoid.
Solder the cathode of a diode to the red pump wire, connect this junction to +12 volts DC.
Solder the anode of this diode to the black pump wire.
OK, so the diode runs between the red and black wires. The junction of the red wire goes to the power supply. So then does the junction on the black also go back to the ground on the power supply? So, the diode just kind of sits in the middle and its used to complete the circuit rather than just the wires, and it keeps surges from hitting the solenoids and pump by allowing it to dissipate in the diode?
I really appreciate you walking me through basics here, I know how frustrating that can be.
The anode (and the wire connected to it) goes to the N.O. normally open contact of the relay.
The common of that contact goes to the ground (0 volts) of the associated power supply.
