adding control to existing design

Thread Starter

zeezz

Joined Jul 15, 2015
9
Hi, below is the design I have for a conveyor belt system. The sensor 1 and sensor 2 are NO and will close when it detects an object. Sensor 1 is positioned at the beginning of the belt while sensor 2 is at the end. System will only run if sensor 1 is ON and will continue till sensor 2 is OFF. Now I need to add another control for a solenoid valve which should turn ON after the object get past sensor 2. Can I achieve this by just adding relays or other passive components?

circuit1.png

Thanks,
z
 

LowQCab

Joined Nov 6, 2012
1,340
Certainly, it's very easy and doesn't require any additional parts,
that is if you don't mind it staying on continuously except when an object is present.

I would imagine that You would want a Timer to limit how long the
Solenoid would remain powered.
.
.
.
 

Thread Starter

zeezz

Joined Jul 15, 2015
9
Certainly, it's very easy and doesn't require any additional parts,
that is if you don't mind it staying on continuously except when an object is present.

I would imagine that You would want a Timer to limit how long the
Solenoid would remain powered.
.
.
.
Yes, I forgot to mention that the solenoid should only turn on for a brief second and then turn off.
Any suggestions are welcomed, thanks.
 

strantor

Joined Oct 3, 2010
5,695
I took the liberty of translating your circuit to ladder logic form because that is a much more intuitive way to represent relay circuits (for me anyway). In doing so, I came to the conclusion that your circuit will only work if the object is long enough to block both sensors at the same time. The motor will start once the first sensor is blocked as you said, but if the object is between sensors, as soon as the object moves clear of the first sensor everything will shut down and your second sensor will do nothing.

20211001_125541.jpg
 

GetDeviceInfo

Joined Jun 7, 2009
1,920
I took the liberty of translating your circuit to ladder logic form because that is a much more intuitive way to represent relay circuits (for me anyway). In doing so, I came to the conclusion that your circuit will only work if the object is long enough to block both sensors at the same time. The motor will start once the first sensor is blocked as you said, but if the object is between sensors, as soon as the object moves clear of the first sensor everything will shut down and your second sensor will do nothing.

View attachment 249223
Curious, is that on a paper towel from the lunch room?
 

Thread Starter

zeezz

Joined Jul 15, 2015
9
I took the liberty of translating your circuit to ladder logic form because that is a much more intuitive way to represent relay circuits (for me anyway). In doing so, I came to the conclusion that your circuit will only work if the object is long enough to block both sensors at the same time. The motor will start once the first sensor is blocked as you said, but if the object is between sensors, as soon as the object moves clear of the first sensor everything will shut down and your second sensor will do nothing.

View attachment 249223
Thanks for this! Yes, the object is long enough to block both sensors.
 
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strantor

Joined Oct 3, 2010
5,695
Thanks for this! Yes, the object is long enough to block both sensors.
In that case you can get rid of two relays. This circuit achieves the same operation:
20211001_193302.jpg
Depending on rating of your sensors and motor, you may even be able to get away with eliminating all 3 relays like this:

20211001_193440.jpg

(Yes, I realize my battery is upside down)
(Yes, on an envelope again)
 
Last edited:

Thread Starter

zeezz

Joined Jul 15, 2015
9
my idea was to have PE1 to be triggered before the motor can run, meaning just triggering PE2 before PE1 was triggered would not activate the motor. But for simplicity wise, maybe I should consider your suggestion.

The one-shot relay you suggested do cost more than my sensor, I'll try to see if there's cheaper alternative. Thanks.
 
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