I am working on a project that moves objects on a surface with electromagnets underneath.

What do you mean by " electromagnet does not repel by simply reversing the current"? Please, tell me more... thanks

Current flowing in one direction causes the electromagnet to attract ferromagnetic objects.
Reverse the direction of the current and the electromagnet still attracts ferromagnetic objects.

If you don't know this then you should quit doing what you are doing now.

 

Very good points. I have measured the current through the zener as I posted earlier, and actually that goes up to 200mA. According to the sheet I posted above just now it handles not more than 5mA?? Am I reading that right? Oh dear... if so, this is a terrible design indeed...

P=I.V
=(0.2A)(12V)
=2.4W

 

Current flowing in one direction causes the electromagnet to attract ferromagnetic objects.
Reverse the direction of the current and the electromagnet still attracts ferromagnetic objects.

If you don't know this then you should quit doing what you are doing now.

I am sorry, but you'd need to give me more information about your statement, otherwise, I don't understand the context of it. Of course, all electro-magnets still attract objects in both directions. I don't see your point and the pertinence of it with the subject of this topic, sorry.

In any case, I have spent a great deal of time studying electromagnets in the past 2 years for this project of mine. There is much more outside this small circuit you have no idea about, but that it is NOT important to know for what we are discussing here. So, please, be polite and don't insult my knowledge that way. I appreciate any feedback given, but please don't assume I don't know anything about a subject by just throwing questions out there without any context to test my knowledge.

I'd prefer to keep the discussion on the topic I have established when I opened this forum if you don't mind.

Thank you for your cooperation and understanding.

 

P=I.V
=(0.2A)(12V)
=2.4W

Thank you!

 

I asked what kind of objects you are attracting and you did not provide an answer.
I asked if you understood how electromagnets attract objects and you responded as if you did not know.
Then you asked me to provide more information which I did.

I am not being impolite. I am being honest and have provided more than enough assistance on your circuit.

A common mistake people make on their wonderful projects is they fail to reveal exactly what they are doing.
So the question still stands. What kind of materials are you attempting to move?

If you no longer require my assistance that is fine with me.

 

Thank you!

No problem

Maybe finding a higher powered one like the 1SMB5927 zener Diode (12V 3W ±5% Surface Mount SMB)
https://www.digikey.com.au/product-...uctor/1SMB5927BT3G/1SMB5927BT3GOSCT-ND/917729

I=P/V
=3W/12V
=250mA

Add a MOV for coil...

And it is starting to look better

 

I asked what kind of objects you are attracting and you did not provide an answer.
I asked if you understood how electromagnets attract objects and you responded as if you did not know.
Then you asked me to provide more information which I did.

I am not being impolite. I am being honest and have provided more than enough assistance on your circuit.

A common mistake people make on their wonderful projects is they fail to reveal exactly what they are doing.
So the question still stands. What kind of materials are you attempting to move?

If you no longer require my assistance that is fine with me.

Ok, let's stop for a minute. I must have missed your question about the kind of objects I am trying to move, and I apologize if I had the impression of been "grilled" for some reason. I am sure that chatting with text and not with actual audible words, the tone gets often misintepreted.

Fact is, I don't see the pertinence of what I want to move with the circuit driving it. If we take that route, I am afraid we'll just waste a lot of time and we'll get out of focus.

Anyway, I am trying to move a puck with a permanent magnet inside and I have already successfully done that with a different circuit prototype that used different components despite very similar characteristics (but, clearly, I must have missed some details...)

What I am working on now is the same exact circuit but with different components, hence the problems that are arising. The previous circuit has worked just fine after several months of experimentation.

The project is based on this other project a friend of mine did at MIT several years ago:

https://dl.acm.org/doi/10.1145/571985.572011

I'll certainly appreciate your assistance and I already appreciate what you have provided me.

Thank you for being communicative with me.

All the best,

 

No problem

Maybe finding a higher powered one like the 1SMB5927 zener Diode (12V 3W ±5% Surface Mount SMB)
https://www.digikey.com.au/product-...uctor/1SMB5927BT3G/1SMB5927BT3GOSCT-ND/917729

I=P/V
=3W/12V
=250mA

Add a MOV for coil...

And it is starting to look better

Indeed! Thank you so much! This helps a great deal.

I appreciated your help very much!

 

Visibly you know nothing about Zener.

Here we go again... is this a polite way to say that? And why saying that? For sure I don't know "enough" about Zener diodes, but that doesn't mean that I don't know anything about anything else.

Can we stop with the insults and continue with a civil and polite discussion?

Thank you.

 

https://forum.allaboutcircuits.com/threads/why-did-this-zener-diode-explode.179806/post-1641162

If that's to refer me to this:

TS forgot to tell us there is real magnets involved.

I don't understand what TS is. Sorry.

 

Thread Starter
fablau

Ok thanks. Well, I talked about magnets in the first post:

The circuit's purpose is to drive an array of electromagnets that can either attract (in which case P-channel MOSFETs are used) or repel (in which case N-channel MOSFETs are used instead).

Did I have to specify that those were "real magnets"? Well, now you know

 

Linear induction motor.

 

The circuit's purpose is to drive an array of electromagnets that can either attract (in which case P-channel MOSFETs are used) or repel (in which case N-channel MOSFETs are used instead).

Your schematic is full of magnets.

The first one I posted? There are not magnets there. What are you referring to? Please, let me know.

 

Linear induction motor.

Wow, that's really something. They are probably using very strong magnets and I am wondering about their amperage!

What I am focusing on is moving small objects like 1 inch x 1 inch max.

 

https://forum.allaboutcircuits.com/threads/why-did-this-zener-diode-explode.179806/post-1640577

Yes, one magnet there. That's the simplified circuit driving just a single magnet. The full circuit (the first one I posted) drives 9 magnets. The full project involves 10 of those circuits plus more circuits with solid-state relays to drive a total of 900 magnets.

 

Magnets have no amperage.

Sorry, I have used the wrong word. I meant the current needed to turn it on at a specific power.

 

Wow, that's really something. They are probably using very strong magnets and I am wondering about their amperage!

What I am focusing on is moving small objects like 1 inch x 1 inch max

My superiors tried in vain to assist you, I choose not too!

 

No problem

Maybe finding a higher powered one like the 1SMB5927 zener Diode (12V 3W ±5% Surface Mount SMB)
https://www.digikey.com.au/product-...uctor/1SMB5927BT3G/1SMB5927BT3GOSCT-ND/917729

I=P/V
=3W/12V
=250mA

Add a MOV for coil...

And it is starting to look better

@click_here Do you think this one has the same characteristics of the one you suggested:

https://www.mouser.com/ProductDetail/Diodes-Incorporated/BZT52HC12WF-7?qs=4z8IqdUrQ/uAek/8AIVCQA==

It still has 250mA forward current despite its power dissipation is just 830 mW. It would have the same package of the ones I'd be replacing (SOD-123)

 

That would be its forward current - i.e. the maximum current if you were using it as a normal diode (anode on the +ve, cathode on the -ve), not as a zener diode.

Unfortunately I don't think that it will work as long as you need 200mA.

If you need a once off hacky solution, glue a through hole next to your pads and solder the wires to it - Otherwise it's version 2 for the PCB

 

That would be its forward current - i.e. the maximum current if you were using it as a normal diode (anode on the +ve, cathode on the -ve), not as a zener diode.

Unfortunately I don't think that it will work as long as you need 200mA.

If you need a once off hacky solution, glue a through hole next to your pads and solder the wires to it - Otherwise it's version 2 for the PCB

Thank you for your reply, now I understand.

Great idea to use a through-hole. Similarly, I think to be able to solder the one you suggested despite being bigger.

Thanks again!