Where is Big Clive when I need him?

[bitingmidge (Peter H)]

These are kind of rhetorical questions for this forum, but if anyone knows the answers please feel free to chip in.

The NEJE laser is a nice bit of kit from an engineering perspective, but completely at the other end of the spectrum when it comes to explanations.

Take for instance the : MULTIFUNCTIONAL AUTOMATIC CONTROL RELAY EXPANSION KIT

Which I know is a relay controlled by the board on the machine via gcode to turn on and off either an exhaust fan or air supply fan. Here are the instructions in full"

Compatible with NEJE motherboards.
For M7 or M8 smoke exhaust system or air-assisted power control.
This kit can only used in NEJE machines which have the M7,M8 port.
Note: If the power supply voltage is higher than 36V, please operate under the guidance of professionals.

Ahh yes there’s the problem - I’m so unprofessional I’m dangerous - I’ll check but I’m pretty sure the 240v 16A marking and the 12v switch input means I won’t eliminate myself. And the manufacturer’s specs seem to confirm that.

But it gets better.

To control the air feed, one of these gadgets goes in (I know how to do that) but there’s another little black box on the 12v line before the pump. In some advertisements there is a dial on that box that can vary the air flow from the pump.

On mine, there is no dial on the box, and the innards look like this:

Why is there a box between the power supply and the pump? Logically the relay is only to switch it on and off so it can’t send a message to this box, yet the instructions tend to indicate that speed is variable.

Mind you, the instructions also have a very stern warning that the whole shooting match should be properly earthed too, which could prove challenging to say the least.

Perhaps one of you fine folk could shed some light?

[jeffeb3]

@bitingmidge

Why is there a box between the power supply and the pump?

That looks like an AC to DC power supply. I suspect the 4 chips on the left are the rectify circuit. The big cap is to reduce the ripple. They usually have a transformer to adjust the voltage down. This one may need a lot of voltage, or the IC (U2) and chip (Q7) on the right are dropping the voltage in DC. Maybe that is an easier way to handle 110/220VAC. It does say 12V on the bottom.

The left wire is connected to 220VAC?

The cap is covering a lot of the board. Is there anything on the other side (like a spot for a potentiometer)? Unless they gave you an easy way to add in a dial, I doubt you can make this adjustable. Without diving deep into it, I wouldn’t know if the adjustable versions change the DC out or PWM duty cycle.

If you had a solid spec sheet on the pump, you could maybe determine if you can replace this PSU with one that can adjust speed.

If you just want to turn it off or on, you can attach a relay or SSR to the output, between this box and the pump.

[bitingmidge (Peter H)]

Thanks very much @BigJeff!

I am away (again) until sometime tomorrow so will continue this as I am intrigued. I can say the pump is powered by a standard plug-in 240V ac to 12v wall adapter, which I presume is a DC output. I will do a much more comprehensive documentation on my return as I am now completely intrigued by this.

The other gadget is the relay (one for air supply and I have another for exhaust) and there is a plug on the board for each of these.

With a bit of digging it’s possible to have lightburn output code to drive them both, and I think even put a time delay on the exhaust - although I also have to see whether the “Door Control” (eStop) input kills everything or just the laser light.

I probably just want to turn it off, but if I need to reduce air for whatever reason, it wouldn’t be too hard to use a fish tank clamp or even regulator on the air tube.

Back to you tomorrow!

[bitingmidge (Peter H)]

Here’s the circuit from beginning to end. I should note that while I claim complete ignorance, I do know what I don’t know and will not be doing anything on the 240V side of things without some expert help on this end. Sadly my resident expert is in poor shape, and I’m spending some time with him while the experts do what they can to make him comfortable while dealing with the melanoma in his stomach.

Therefore I appreciate the input even more than I normally do.

@jeffeb3

That looks like an AC to DC power supply. I suspect the 4 chips on the left are the rectify circuit. The big cap is to reduce the ripple. They usually have a transformer to adjust the voltage down. This one may need a lot of voltage, or the IC (U2) and chip (Q7) on the right are dropping the voltage in DC. Maybe that is an easier way to handle 110/220VAC. It does say 12V on the bottom.

PSU (I had to look that up! )
It’s a normal plug adapter (except it has a UK plug and a travel adapter, so I may switch it out in time).
240V 60Hz 1.0 A in - 12.0V⎓ 2.0A 24W out. I don’t understand the symbol after the 24.0W is but we are talking DC supply.

@jeffeb3

If you just want to turn it off or on, you can attach a relay or SSR to the output, between this box and the pump.

The psu feeds to a split into which is inserted the relay pictured in the first post - which is triggered by the board and therefore a signal from lightburn’s code.

Then comes the little black box.

@jeffeb3

The left wire is connected to 220VAC?

No, it’s all 24VDC

Had I read the instructions I would have seen in the fine print there is no airflow adjustment. See DC50 in the Perfornagam Diagram below. "Performagam" is my new favourite word that covers all things technical!

So I’ll skip the little black box for a bit and go onto this - I assume the nomenclature DC50 relates to “DC” and “well 48 is close enough to 50l/min to sound great”.

The box is quite enlightening at least in terms of whether it’s second hand packaging or not!

So now back to the little black box. The reverse side of the board is pretty clear.
The

I did get as far as checking out those chips - JMTK130P04A but the info is in electro-speak which you will understand but I have no clue.

I guess there’s no need to worry about any of this, I’ll just assemble it logically in accordance with the complete lack of instructions and it will be fine!

Cheers!

[bitingmidge (Peter H)]

FOOTNOTE -

Heavily influenced by “influencers” who had tested Aquarium pumps vs the real deal, and found them to be cheaper but to underperform purpose made pumps (whatever that means), I did two things -

1. I bought this genuine NEJE accessory, which clearly turns out to be an aquarium pump, manufactured by an aquarium pump manufacturer.

2. Referred my son-in-law to a couple of youtube videos which explained his idea of using an aquarium pump was a bad one despite them promising more output for less money. Told him I’d buy him a “proper” one for Christmas, so ordered a not inexpensive but genuine SCULPFUN accessory.

This turned out to be a clone of the one I have, but with a lot of fish drawings on the box, (presumably this was not the new packaging) and a distressingly similar Performagam. It might be quite embarrassing on Christmas Day!!

Death to all influencers I say!!

[pony1023 (Steve)]

@bitingmidge

I don’t understand the symbol after the 24.0W is but we are talking DC supply.

Someone please correct me if I’m wrong, but I’ve always thought that symbol is telling us, positive is in the center of the barrel connector on the output line, with negative on the outside of the barrel. The way logic would want it, so you don’t accidentally shock something or yourself.

I’m waiting to find the device that has the inverse symbol on the power supply.

[bitingmidge (Peter H)]

@pony1023

positive is in the center of the barrel connector on the output line, with negative on the outside of the barrel.

That’s a wonderfully logical symbol and explanation. I’ll tick that box as a bit of knowledge gained, thank you!

[jeyeager (Jason Yeager)]

Most guitar pedals are powered center negative.

[jeffeb3]

@bitingmidge

Sadly my resident expert is in poor shape

I’m sorry to hear that. I’m glad he has you to help him.

@bitingmidge

No, it’s all 24VDC

Hmm. Ok. My first guess was wrong then. My new guess is that this is an H-Bridge circuit. Those are often used to control DC motor direction and speed:

H-bridge DC Motor Control Using Complementary PWM, Shoot-through, and...

I guess the secret sauce is in U2. That chip might be responsible for a slow speed up or for detecting faults in the pump, or power filtering.

[pony1023 (Steve)]

Shocking.

All joking aside, I get it’s not a safety concern at that voltage, but surprised that’s the standard for guitars in the US.

[jeffeb3]

It’s certainly dangerous for electronics. I haven’t ever found a pattern, but I check that symbol before reusing a wall wart from my parts box.

[Fabien]

@bitingmidge

The box is quite enlightening at least in terms of whether it’s second hand packaging or not!

I can confirm this is the exact model I ordered from ali a few month ago for a whooping 50€
https://fr.aliexpress.com/item/1005004383675292.html?spm=a2g0o.order_detail.order_detail_item.3.8a847d56KShWUN&gatewayAdapt=glo2fra
Mine was 30L/min though… wonder how the exact same product can produce twice the volume but hey… maybe it runs (and burns?) a lot faster

EDIT: my bad, I can see this is the DC model, mine runs on AC, so this can axplain afew differences

Concerning speed/flow adjustment I wouldn’t bother too much, you end up keeping it off or running it full blast anyway (wether your engraving or cutting)
Even at full blast it’s pretty silent, apart from vibrations if you happen to let it sit any other way than on it’s rubber feet

[bitingmidge (Peter H)]

@jeffeb3

That chip might be responsible for a slow speed up or for detecting faults in the pump, or power filtering.

I wondered (based on absolutely no electrictronics knowledge input) whether it somehow senses load and reduces or increases current by magic?

@Fabien

the exact model I ordered from ali a few month ago for a whooping 50€

This one was $65US but you don’t want to know about the freight!

[jono035 (Jono)]

@jeffeb3

I guess the secret sauce is in U2. That chip might be responsible for a slow speed up or for detecting faults in the pump, or power filtering.

That chip is the thing providing the gate drive signals. Doesn’t look like there’s any feedback, it’s just implementing what is probably an undervoltage lockout (voltage divider of R2 and whatever is just off the screen) and sending out the H-bridge PWM signals.

It’s an extremely basic motor controller. I guess if the pump itself isn’t particularly beefy it may last ok, but it’s pretty solidly junk tier design, I’m afraid.

[bitingmidge (Peter H)]

@jono035

but it’s pretty solidly junk tier design, I’m afraid.

Surely not, have you actually read the Performagam??

The packaging does say somewhere that all parts are replaceable, but I have searched to the ends of the earth to discover what they can be replaced with and failed to find a clue. I suspect one buys them from the same place one buys parts for one’s el cheapo brad nailer.

[jono035 (Jono)]

@bitingmidge

Why is there a box between the power supply and the pump? Logically the relay is only to switch it on and off so it can’t send a message to this box, yet the instructions tend to indicate that speed is variable.

That pump looks like it’s probably a linear motor type pump, so a solenoid shuttling back and forth. When AC is applied they solenoid gets energized, de-energized and then re-energized in the opposite direction by the AC waveform. With DC, something specifically needs to power it up, take power away and then connect power in the reverse direction for it to do the pumping. That’s what that box is doing. DC in on the red/black wires, the 4 big chips on the left are the H-bridge that chops it up and sends it out the blue/brown wires as a square wave.

I can’t see how that hardware would have speed control added. Is there anything on the other side of the board?

Either way, for controlling it the easiest option seems to be what you’re doing anyway, a relay between the DC input to that box and whatever power supply you’re using.

If you’re worried about safety/grounding, I’d just make a plan to replace the AC/DC converter with a more ‘known’ brand one. The cheaper end of that market is probably the most unknowingly dangerous stuff that people interact with on a day to day basis, electronics wise!

[jono035 (Jono)]

@bitingmidge

The packaging does say somewhere that all parts are replaceable,

Very true. Replaceable, all you’ve gotta do is buy a 2nd one to harvest for spares!

[bitingmidge (Peter H)]

@jono035

I can’t see how that hardware would have speed control added. Is there anything on the other side of the board?

No, I have discovered that it’s not designed for speed control, and @Fabien has pretty much confirmed that I won’t need it anyway. (Just another dose of how too much book learnin’ can be bad for a girl.)

@jono035

If you’re worried about safety/grounding, I’d just make a plan to replace the AC/DC converter with a more ‘known’ brand one. The cheaper end of that market is probably the most unknowingly dangerous stuff that people interact with on a day to day basis, electronics wise!

@BigClive has taught me many things, and that is one of them! A dodgy AC/DC converter with a UK plug via the cheapest travel adapter I’ve ever seen is not my preferred method of guaranteeing more Christmases! Having said that, I’ll probably unknowingly buy a dodgy one with an Aus plug but pay full freight for it!

[jono035 (Jono)]

@bitingmidge

No, I have discovered that it’s not designed for speed control, and @Fabien has pretty much confirmed that I won’t need it anyway. (Just another dose of how too much book learnin’ can be bad for a girl.)

With our 120W CO2 laser, I find myself adjusting the flow rate reasonably often. Full flow rate through the main nozzle for cutting most things, low flow rate through the the main nozzle for cutting paper/thin plastics or engraving easy stuff, low flow rate through an external horizontal ‘nozzle’ if I’m engraving stuff that needs to look good or is a bit more challenging. I’m doing that by just partially cracking open the valve, though, so there are definitely other ways to approach it.

@bitingmidge

@BigClive has taught me many things, and that is one of them!

Yes, this has been a crusade of mine for many years and the reach he has had with spreading that message is great to see. One of his many contributions to society, in addition to distillation/carbonation of many things that clearly just shouldn’t be.

@bitingmidge

Having said that, I’ll probably unknowingly buy a dodgy one with an Aus plug but pay full freight for it!

If you’re looking for known-good stuff on the cheap end, Mean Well stuff is a good balance of price vs quality. That’s what my go-to is both home and at work when we just need a basic power supply. Here in NZ we have a company, Wellforces.co.nz, that re-sells Mean Well stuff directly and without too much markup. Alternatively, you could also try an old laptop supply. The pump may still work fine on 19V. 24V is kind of uncommon enough to be awkward when it comes to consumer power supplies, unfortunately.

[bitingmidge (Peter H)]

@jono035

24V is kind of uncommon enough to be awkward

It’s 12v so I was just going to get a slightly higher rated (2.5A) adapter from Jaycar, and hope for the best!