Maker Pro
Maker Pro

Need help with a circuit

ChickenNuggets

Sep 30, 2016
2
Joined
Sep 30, 2016
Messages
2
I have two circuits, Circuit A that runs at 5 volts and Circuit B that runs at 48 volts. It is basically an arduino that is connected to a relay connected to power supply connected to fans. However when Circuit A turns off, Circuit B (the fans) are still running. I know that it is not the code of the arduino, and I do not think that it is the arduino is the problem at all.
How do I make it so when Circuit A fails, Circuit B turns off as well, so it is just not running "out of control" per se.
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
12,615
Joined
Nov 17, 2011
Messages
12,615
A schematic could be helpful ;)
How is the aduino controlling the relay?
What does "when Circuit A fails" mean? In which way does the circuit fail, how does the failure show on the output controlling the relay?
 

ChickenNuggets

Sep 30, 2016
2
Joined
Sep 30, 2016
Messages
2
I don't have one. The arduino is controlling the relay by having it be on for 3 seconds then off for 2 seconds. When I unplug the battery to the arduino the fans are still running. I need to make it so when the arduino gets turned off or fails, the fans stop too.
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
If the fan is still running when the arduino is powered down then you have the fans connected to the normally (NC) closed relay contacts.

Chris
 

HellasTechn

Apr 14, 2013
1,559
Joined
Apr 14, 2013
Messages
1,559
That is correct Chris.

I don't have one. The arduino is controlling the relay by having it be on for 3 seconds then off for 2 seconds. When I unplug the battery to the arduino the fans are still running. I need to make it so when the arduino gets turned off or fails, the fans stop too.

You need to change your fan wiring to the Normally open contacts and then alter your arduino code so that it will disengage the relay when it was supposed to "engage" it and to "engage" it when it was supposed to be "disengaged"

In other words make the output of arduino controlling the relay go high when it would be low and low when it would be high.

does that make sense ?
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
I don't have one. The arduino is controlling the relay by having it be on for 3 seconds then off for 2 seconds. When I unplug the battery to the arduino the fans are still running. I need to make it so when the arduino gets turned off or fails, the fans stop too.
If it is cycling correctly ON - OFF while the Arduino is running then it's unlikely that you need to change your code. Not from the description above, that is. Just change your wiring to the Normally Open (N/O) contacts of the relay.

Chris

Edit: I just noted that your ON - OFF times aren't symmetrical. If the timing sequence is now correct then Constantine is correct. You'll have to change your code too.
 
Last edited:

HellasTechn

Apr 14, 2013
1,559
Joined
Apr 14, 2013
Messages
1,559
Edit: I just noted that your ON - OFF times aren't symmetrical. If the timing sequence is now correct then Constantine is correct. You'll have to change your code too.

That is why i suggested him to alter the code :) to keep timing !
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Yes, that's why I corrected myself. "CYA"! :p

Chris
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
Well, it doesn't have to be the use of NC contacts. It could be that whatever circuit is driving the relay needs to be either pulled up or down to open the relay.

Bob
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
When I unplug the battery to the arduino the fans are still running. I need to make it so when the arduino gets turned off or fails, the fans stop too.

Did you miss this?

Chris
 
Top