What can I use to control solenoids?

Thread Starter

marimbob

Joined Jun 23, 2020
7
Hi,

I've built a device that utilizes 2 DC push solenoids, and an AC cooling fan. I'm powering the solenoids with a variable bench power supply set at 30V DC (they're drawing about 25V, and 2-3A). I need the first solenoid to be activated approximately 60-120 times, at a rate of two cycles per second, and then both solenoids need to be activated simultaneously approximately 60 times, while the fan runs continuously. Assuming that I know little or nothing about electronics, can you suggest a simple, dependable, control set up? Of course the lower the cost, the better for keeping production costs down.

Thanks,

Marimbob
 

MaxHeadRoom

Joined Jul 18, 2013
20,894
Two times per second! Are the solenoids capable of operating at this rate?
I would think either a Smart Relay, or a small 8 pin Picmicro would do it.
Max.
 

Thread Starter

marimbob

Joined Jun 23, 2020
7
Two times per second! Are the solenoids capable of operating at this rate?
I would think either a Smart Relay, or a small 8 pin Picmicro would do it.
Max.
Thanks for the reply MaxHeadRoom. I currently have the solenoids connected to spring loaded switches, and when I push one at about that rate, it operates fine. The only trouble is that I have them both connected to the same power leads, and they won't both activate simultaneously, as I need them to. I have to push the buttons a fraction of a second apart. I may need to get a separate power supply for each. Thanks for the info, I'll look into the Smart Relay and the Picmicro.

Marimbob
 

MisterBill2

Joined Jan 23, 2018
6,311
You can purchase an industrial PLC from Automation Direct that can provide exactly the function you need and it will be in a package that will be quite durable and safe to use. Plus the programming software is free. So you will not need to mess with some dinky little processor board and assorted pieces to build a control system that will need to be assembled in some sort of enclosure.
 
you need SSR(solid state relay) to control the solenoid. the kind of things that you are mentioning if you wan't to build it cheap you have to use any kind of cheap microcontroler.


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MaxHeadRoom

Joined Jul 18, 2013
20,894
You can purchase an industrial PLC from Automation Direct that can provide exactly the function you need and it will be in a package that will be quite durable and safe to use. Plus the programming software is free. So you will not need to mess with some dinky little processor board and assorted pieces to build a control system that will need to be assembled in some sort of enclosure.
The Smart Relay, made by a few companies, is exactly that without the overkill of a full blown PLC. :cool:
Max.

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Thread Starter

marimbob

Joined Jun 23, 2020
7
MaxHeadroom, dendad, manojroy123, MisterBill2,
I found these after searching a bit, after reading the manual, it looks like I can program this to activate solenoid 1 at specified intervals, for a specified duration, then activate both solenoids 1 and 2 simultaneously, also at specified intervals, for a specified duration. The english was poor, so I'm not confident that it will do what I want. Can you tell if it will work?

https://www.tergolw.com/index.php?main_page=product_info&products_id=835448

Other relays like this that I found would seem to require a controller.

https://www.amazon.com/SainSmart-101-70-100-2-Channel-Relay-Module/dp/B0057OC6D8/ref=sr_1_2?dchild=1&keywords=smart+relay&qid=1593035139&rnid=16310161&s=industrial&sr=1-2&pldnSite=1

such as an Arduino Uno like this:

https://www.banggood.com/Geekcreit-UNO-R3-ATmega328P-Development-Board-For-No-Cable-p-964163.html?gmcCountry=US&currency=USD&createTmp=1&cur_warehouse=CN

Any thoughts?

Thanks,

marimbob
 

MaxHeadRoom

Joined Jul 18, 2013
20,894
According to the manual, it seems it would do the job, preferably you would use a BEMF diode across the solenoid coil, for high energy devices, this tends to cause a slight delay on drop out, but unless the solenoid armatures are particularly large, it should not make a significant difference.
Max.
 

MisterBill2

Joined Jan 23, 2018
6,311
You can reduce the dropout delay by putting a resistor in series with the diode. That still reduces the spike, but it also reduces the current, which causes earlier drop out.
 

MaxHeadRoom

Joined Jul 18, 2013
20,894
I used the 1n4007 for this kind of device, now though they have the fast version, UF4007.
Usually delayed drop out is not a problem for the typical solenoid, unless it is a really large device such as a brake/clutch etc.
Max.
 

Thread Starter

marimbob

Joined Jun 23, 2020
7
According to the manual, it seems it would do the job, preferably you would use a BEMF diode across the solenoid coil, for high energy devices, this tends to cause a slight delay on drop out, but unless the solenoid armatures are particularly large, it should not make a significant difference.
Max.
Awesome! That unit is reasonably affordable, though it might take some trial and error to get the timing right with the programming. When you say "use a BEMF diode across the solenoid coil", does that mean that I would cut the positive power lead between the relay and the solenoid and splice the diode in? The solenoid isn't particularly large.
uxcell Push Pull Type DC Electromagnet Magnet Solenoid, 15 mm 45N DC 12V 2.5A
 

MisterBill2

Joined Jan 23, 2018
6,311
So the diode is connected in an "inverse-parallel" arrangement, as Max described, so that when the coil is energized the diode is biased OFF, and when the coil drive is switched off, the current flows through the diode, preventing a voltage spike from being generated.
 

Thread Starter

marimbob

Joined Jun 23, 2020
7
So the diode is connected in an "inverse-parallel" arrangement, as Max described, so that when the coil is energized the diode is biased OFF, and when the coil drive is switched off, the current flows through the diode, preventing a voltage spike from being generated.
Thanks for the clarification, that's helpful!
 
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