Need help understanding a circuit diagram. how do i connect this circuit on the breadboard?
I'm trying to do this project below but the connections are not very clear.. help please :c
Not to be funny, but I wouldn't even do it that way with a loose relay, a transistor with resistor, and the diode. I'd go for a relay module with all the components, perhaps including opto-isolation, all in one.
One like this can be powered from the 5V of the Arduino (those relays are about 75mA, but be aware of the total current) and life's a lot easier. (No isolation on this one though.)
Source of those pix.
Thanks for the reply, .. So after using the relay module, the connection should look like this right?
Will there be any issues with this connection? cause I'm powering up my nano with usb.
LM317 is not a buck converter. Have you wired it the wrong way round and you supply 12V to the circuit and the LM317 drops the 12V to 5V for the Nano?
Did you mean to connect the pump to the NC connection on the relay board so it will run all the time unless stopped by the Nano?
I want to convert my 5 v to 12 v to supply the WATERPUMP . and yes i meant to connect it to the NC Connection.
xMichelle:
I want to convert my 5 v to 12 v to supply the WATERPUMP . and yes i meant to connect it to the NC Connection.
Then you will need a boost converter and not a buck converter.
Depending on how much current the 12V pump motor draws you may have power problems converting 5V to 12V.
the converter that i bought is this below, can i just increase the 5v to 12v like in the video tutorial , as for the current it outputs up to 1.5A. Sorry i'm not very good with electronics and i'm just following the youtube tutorial.
Unless I'm missing something, the mentioned buck converter will only reduce voltages. To increase voltages you need a boost converter (example).
The module cited is not even a "buck converter" - it is wrongly described (but that is hardly surprising).
This is a simple LM317-based series regulator which reduces voltage by converting the difference between input and output as heat (and thus the somewhat inadequate heatsink!), in no way related to any sort of "buck" or "boost" converter which are efficient switchmode devices.
And the diagram indicates no source of 5 V which would be sufficient to power an actual boost converter in any case.
What is required is a 12 V power supply with the necessary capability to power the pump. The LM317 regulator can then be used to provide the necessary 5 V to power the Nano so you do not need a USB supply.
So how do i approach this? I want to power up my arduino nano through usb, and use the 5v Output from the 5v pin and convert it to 12v to supply the 12v DC Pump.
Do i get a boost converter instead?
xMichelle:
I want to power up my arduino nano through usb, and use the 5v Output from the 5v pin and convert it to 12v to supply the 12v DC Pump.
You might want to use the Arduino to power the motor, but don't.
You'll (probably) get away with the 70-odd mA for the relay coil, but you really should use a separate supply for the motor.
I'd go the other way: start with 12V from a wall wart for the motor, and take that down to 5V for the Arduino, and use that 5V for the relay coil too.
(Subject to others advising about the wisdom of powering the Arduino from a power supply which may be noisy from the motor, and methods to mitigate that.)
All right thanks so much!!
lindsayBoxer:
You might want to use the Arduino to power the motor, but don't.
Yeah, that was the nub of my reply. 
As you're switching DC you may also want to look into MOSFETs as electronic switches. More efficient, smaller and cheaper than a relay.
How much power does the pump take? Any more than 2.5W will overload the USB and the PC will cut off power to that outlet.
The one in the video clearly says 4.8W. You may be able to power this from a 1A phone charger but probably not. The video schematic does clearly show the LM317 used to convert 12V to 5V. But nowhere in the video does it show the 12V power supply. There must be a 12V power supply.
So if i were to use the 12v supply and convert it into 5v, which pin of the arduino nano do i connect it to?? do i connect it to the vin of the arduino nano? i heard the vin pin is for 7v to 12vdc so im confused.
The 5V pin. It may be used as an input or output. If you are using it as an input then don't connect to Vin.
The 12V supply goes to the Vin pin; you can then indeed get some 5V from the 5V pin.
Note that you can get only a very little current out of the 5V pin before the regulator overheats. I'd estimate <50 mA when supplying the Nano with 12V.