Check my wiring, so I don't blow something up

Other Hardware General Electronics
1

Im trying to run some pumps with a 16 channel relay board. I have a total of 16 pump. I only did 2 pumps for the picture to make it simple. Only one pump will be on at a time. Can someone look through my wiring diagram to make sure I have it right. A few questions I have is

  1. Should I run the pump GND back into relay?
  2. Does the pump GND need to go back to the PSU ground, the same one thats feeding the 12 volt side on the relay board?
2

I can't see the diagram but in answer to your questions all GNDs on the coil side of the relays should ber joined and all GNDs on the switch side of the relays should be joined. I would not join the 2 GNDs together though.

3

Many relay boards “do not” need a GND as the Arduino 5v pin is connected to the input connector.

We need to see a schematic of the relay card.

4

Won't work - you have no power to the pumps - those are relays and you need power to each of the pump relays - each relay has NC/NO contacts - you need pump power to the appropriate side of each relay

There are some other things that look funny but not sure so will let others take a shot at that

See also the How to use the forum post at the top on how to post images

5

Agreed.
You wiring is wrong.

This is how it should be wired:

+12V => [Pump+ pin]
Relay COM pin: [Pump- pin]
Relay N.O. pin: 12V - pin (called RETURN)

Operation
Normally Open (N.O.) MEANS that when the relay is OFF, there is no connection.
When relay energized, N.O. pin shorts to COM pin, connecting pump - to GND.

Keep in mind, this is only ONE of TWO ways it can be done.
Instead of switching the pump [-] to the 12V P.S. [-] (called switching the pump RETURN line)
it is also possible to hard wire the pump [-] to P.S. [-] and put the relay contacts IN SERIES
BETWEEN the P.S. [+] and the pump[+], thus switching the POS side of the pump instead of
the NEG side. Six of one , half a dozen of the other, but the preferred way is to switch the
return and put a flyback diode across the pump (cathode to +, anode to -) to prevent back
emf when the pump power is switched off. While the pump is a MOTOR , NOT an INDUCTOR
(like a solenoid), the flyback diode is not mandatory like it would be with an inductor.

6

OP’s image:

1876×1430 516 KB

Don’t forget to add kickback diodes across the pumps.

NOTE: It appears that the Arduino gets its 5v power from a regulator on the relay card, a bit unorthodox.

7

larryd:
It appears that the Arduino gets its 5v power from a regulator on the relay card, a bit unorthodox.

Common with a 16-channel relay board.
I do hope it actually has the buck parts fitted (some don't).

These 16-channel boards also have a design fault. Optos, but no user selectable opto isolation.

The HC-05 is connected wrong.

  1. needs 5volt power (look at writing on the back)
  2. TX/RX should be connected to Serial1 (or 2 or 3), NOT to pin 0,1.
  3. BT RX pin should have a 1k:2k voltage divider (level shifter).
    Leo..