System: Arduino Nano wtih 6 relay, 5 button and 5 diode lighs
Power from: car battery (12v) (running car)
Going to connect VIN PIN and GND too the car battery. (with fuse )
But can nano handle det 12v bettery + enginestarte and dynamo ( Running car ) ?
What did you do here?
don't do it. did you measure the charged battery voltage and compare it with voltage interval recommended for voltage input of regulator on nano?
No think it 12v -14v
And my nano dont have det RAW just VIN 
over 12 V is too much for the regulator on Vin. (Vin is it not RAW)
aah ok:)
Can i use this: DC-DC 12V to 5V/6V/9V 2/3A 15W Converter Step Down 2A/3A 15W Power Supply Module | eBay
and make from 12v too 9v ? 
Then I am safe?
it depends on power consumption of relays
ah
and this: 1PCS 5V One 1 Channel Relay Module Board Shield For PIC AVR ARM Arduino | eBay
It work on 5v USB from pc So it shuld work on 9v ?
sorry, now I read your post again. the battery is the battery of a running car engine. I do not now if the step-down converter is enough to protect the Arduino
aah any other her, how can help me But thx for the help you gave me
try adding to title "in a running car". it will attract car experts
thx
Knutarn:
And my nano dont have det RAW just VIN
Juraj:
(Vin is it not RAW)
Some boards call the input of the onboard voltage regulator V-in, other boards call it RAW.
It is the same thing.
Not wise to buy 5volt relay modules for a 12volt power supply.
Buy 12volt relay boards, so you don't have to use a 12>5volt buck converter for the relays.
Not wise to run a Nano on 12volt, and certainly not on a running car.
Get a 5volt buck converter, and power the Nano directly from 5volt.
Leo..
Or ( less efficient, but who cares?) a simple linear reg such as a LM7809.
Allan
Wawa:
Some boards call the input of the onboard voltage regulator V-in, other boards call it RAW.
It is the same thing.Not wise to buy 5volt relay modules for a 12volt power supply.
Buy 12volt relay boards, so you don't have to use a 12>5volt buck converter for the relays.Not wise to run a Nano on 12volt, and certainly not on a running car.
Get a 5volt buck converter, and power the Nano directly from 5volt.
Leo..
Then I buy this: DC-DC 12V to 5V/6V/9V 2/3A 15W Converter Step Down 2A/3A 15W Power Supply Module | eBay
and make it 12v to 9v 9v is better then 5v?
Knutarn:
Then I buy this
And what about the relay board.
You might just be able to power ONE relay from the Nano's 5volt pin at that voltage, but not four.
Knutarn:
9v is better then 5v?
Why do you think that.
If you need 5volt, and you have 9volt, you need to get rid of four volts.
Leo..
Wawa:
And what about the relay board.
You might just be able to power ONE relay from the Nano's 5volt pin at that voltage, but not four.
Why do you think that.
If you need 5volt, and you have 9volt, you need to get rid of four volts.
Leo..
ååh Then I misunderstood it. Then I use 5v in the vin pin
I can drive 5 relay with USB 5v power from my pc. So I think it shuld work with 5v?
Knutarn:
ååh Then I misunderstood it. Then I use 5v in the vin pinI can drive 5 relay with USB 5v power from my pc. So I think it shuld work with 5v?
No, V-in (RAW) is the input of the onboard 5volt regulator.
V-in on a Nano needs at least 6volt for the regulator to produce a clean 5volt for the micro.
If you have a reliable 5volt source, then connect it directly to the 5volt pin (bypassing the onboard 5volt regulator.
You can draw about 500mA max from a USB2 socket.
The Nano has a small backflow protection diode in the USB line with a rating of 500mA absolute max (I woudn't go over 400mA).
Blue sugarcube relays, when active, draw about 80mA each from the 5volt rail.
That means that the Nano could get in trouble (smoke) when more than four relays are active.
Leo..
Wawa:
No, V-in (RAW) is the input of the onboard 5volt regulator.
V-in on a Nano needs at least 6volt for the regulator to produce a clean 5volt for the micro.
If you have a reliable 5volt source, then connect it directly to the 5volt pin (bypassing the onboard 5volt regulator.You can draw about 500mA max from a USB2 socket.
The Nano has a small backflow protection diode in the USB line with a rating of 500mA absolute max (I woudn't go over 400mA).
Blue sugarcube relays, when active, draw about 80mA each from the 5volt rail.
That means that the Nano could get in trouble (smoke) when more than four relays are active.
Leo..
hoo thx
Then I going to buy this: https://www.ebay.com/itm/DC-12V-to-USB-5V-3A-15W-Converter-Regulator-Step-Down-for-Car-GPS-iPhone-Samsung/142625731712?hash=item213527f480:g:0S8AAOSw7qdZ6G7m
And connect the nano on usb? A better connector than the crappy header pins (which can fall out, make poor contact, etc)
and make relay (opto isolator)
its ok?
and I
There are also 5volt USB supplies that plug into the cigarette lighter of a car. Might be easier.
Leo..
Wawa:
There are also 5volt USB supplies that plug into the cigarette lighter of a car. Might be easier.
Leo..
yes i know. but going to make the hidden. you can se here:
soon finnish. but need to get the power fixet:D