Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - petespaco

Pages: [1] 2 3
1
MOT:  There are plenty of youtube videos out there abut rewinding MOT's.  Good that you have lots of capacitors.

Work safe and "keep one hand in your pocket" when working with high voltages.

2
You might also try rewinding some 1000 watt Microwave Oven Transformers  (MOT).  You could rectify their output.  I don't know how ripple free the power to these induction heaters needs to be, so I don't know how much capacitance it would take to smooth it.  But, if you did use lead acid batteries, they  would be a good ripple reducer, I'd think.    Then your "MOTs"  would simply be acting as a battery charger.
   I would suggest simply going the MOT route with a lot of capacitance  (just under the amount that would trip the mains breaker on power up), but, if you have to buy them, you might as well simply buy the server power supply anyway.
  Depends on how much tinkering you want to do.
  I tried to find the unit that you (badpeter) ordered on Ebay.  I think I found it, since it was the only one I saw that had the fan wires zip tied to a post.  I didn't see any place on the back side of the board where   the buck converter parts might be located.  But it could be hiding in there someplace, I suppose.
  Was it this one?:
https://www.ebay.com/itm/1800W-ZVS-Induction-Heating-Board-Module-Flyback-Driver-Heater-Tesla-Coil-Fan-US/123420945506?epid=2291469563&hash=item1cbc762c62:g:D2UAAOSwFnxbwEuo

3
That sure was a successful test.
    Is the "glowing" color that we see on the video that same as what you see in person?  Do you do anything special with the white balance of your video camera?

I am starting to work on establishing operational upper frequency limits on these devices.  I wonder how high they can go and still work okay.  Today, I certainly exceeded that number, so now I will have to "back up" to see where the real tripping point is.
So far, I hypothesize  that the data I gather from the 1000 watt unit will transfer directly to the 1800 and 2500 watt devices, since their gate circuits appear to be identical.  (Having said that, and seeing that two of three gate circuits are in parallel, I WILL have to verify that some day.)
By the way, I am using a cheap inductance meter for these measurements.  I think it is this one:
https://www.ebay.com/itm/LC100-A-High-Precision-Digital-Inductance-Capacitance-L-C-Meter-Tester-SMT-Clip/253959986062?hash=item3b2131db8e:m:mOpTSkV_q1oIM9pHKxVlPfw

Here's the record of this morning's test:
Objective:
  Determine the lower work coil inductance range for safe, useful operation of the popular 1000 Watt to 2500 Watt ZVS induction heaters.

Date: march 18, 2019

Subject for testing, March 18, 2019:
Testing a 10" U shaped work coil on the 1000 watt unit.

Method:
Make up a "one turn" coil to use as a worst case situation.  This coil is simply 25" of 1/4" OD copper tubing that is bent into a "U" shape, with about 3/4" between the arms.

Summary:
My initial conclusion is that the oscillation frequency observed during this test is somewhat beyond the safe or useful upper limit for this design.
  I hypothesize that the lower limit for work coil inductance is about 1.0 microhenry.
-----------------------------
Notes:

First I checked out the system using a "stock" 2" ID 6 Turn coil.  It ran, as it normally does,  at  about 6 amps of idle current.

Then I removed the 6 turn coil and replaced it with this "U" coil:
The measured inductance of this "U" coil is about 0.240 micro henry.
At present, the coil is actually several inches longer than 10.  I call it a "10 inch coil" because, once fully shaped, it would have a work area about 10 inches long for heat treating knife blades.
It has a spacing between the tubes of about 3/4".

For reference, these 1000 watt ZVS heaters come with coils that produce resonant frequencies between about 103 kHz and about 83 kHz.  These coils have measured inductances of about 1.05 to 1.38 micro henry.

Results:
The system  DID oscillate, but at about 154 kHz. 
And the gate waveform degraded significantly from the almost square shape it has with the "stock"  6 turn X 1 1/2" to 2" ID coils.  The signal almost looked like a sine wave with a slightly flattened top, both the leading AND the trailing edges.

  The idle current went to 16 amps.  I think this extra 10 amps is caused by the degraded gate signals causing the Mosfets to be running in linear mode for a good share of the time.  Also, the capacitors heated rapidly within a minute or so of "power on".



4
Flyrod: "So do these boards use the same pull up resisters for gate drive?"
If you mean "do they use the same gate drive circuit as does the 1000 watt unit?"
Yes, for the 1800 watt unit that I have, at least.
The same 470 ohm 5 w wirewound resistor, 10K resistor, 12 volt zener  and FR307.

If you mean: "do all 4 gate drivers use the same pull up resistors for gate drive?"
The answer is still "yes".

Pete Stanaitis
---------------

5
Hello Mads.
  Putting the standoffs on the bottom is a good Idea.  I wish I'd have thought of that.

It is interesting to see how many slightly different implementations of these devices exist.  Your device is the first one I've seen where the work coil is oriented horizontally.
On my 1800 watt unit, there was no heat sink compound, but they did have piece of thin, white material sandwiched between the Mosfets and the heat sink.  I thought about replacing that material with heat sink compound, but so far it hasn't been a problem.  I did blow up one Mosfet, but that was my own fault for paralleling one gate with too low of a resistance.  I knew better, but did it anyway.  Such is the life of a novice!

By the way, I just powered  up my 2500 Watt ZVS induction unit and did a youtube video of it yesterday.
It is here:
/>You will see my messy method of getting the water away from the board.

Pete Stanaitis
---------------


6
Thanks for the kind words.
  I should have gotten back to you sooner.
I don't think the coil will melt in 30 seconds or so, but it will transfer a lot of heat back to the standoffs that it is connected to.
When you say "get a 7/16 inch bolt red", do you meant just the head or a whole bolt?  And, how hot is "red"?   If it just needs to glow a low to medium read color to the naked eye, you should be okay,  But if you need it to be bright red or orange. it can take quite a while, once the bolt's temperature passes the "curie point", becoming nonmagnetic.  That's because the heating rate will slow considerably.
  if you plan to use a work coil of less than 7 or 8 turns, please let me know how it works out. 

That's an Atlas 10F lathe in the background.  Wish it was a South Bend, but it works for me.

Pete Stanaitis
---------------   

7
Dual Resonant Solid State Tesla coils / Re: Chinese DRSSTC driver woes...
« on: February 06, 2019, 12:17:28 AM »
I can't see why a 555 would ever run hot.

8
Dual Resonant Solid State Tesla coils / Re: Chinese DRSSTC driver woes...
« on: February 01, 2019, 04:45:55 PM »
I was hoping that many Tesla enthusiasts would jump in on this one.  I haven't played with a Tesla coil since 1956, so I know  nothing.
But----  Isn't that little toriod  that is hanging off the side of the board supposed to be the "feedback" element?  Shouldn't the power wires or something make one turn through it, as in one of the pictures show in the "details" link in the aliexpress ad?
  I attempted to add a picture of the feedback setup on their earlier model, but I don't see it here.

9
It's working fine now:
/>
Pete Stanaitis
---------------

10
Mads-  Sorry to hear about your shipping issues.  I did get one or two of the 1000 watt units where one lead of  the 470 5 watt resistor had broken off the board.   The buck converter terminal on your board is different from any I have seen.  That makes me wonder how many actual manufacturers are in this game, and how much actual thought goes into each one's design variations.

the_anomaly-  I assume you will need to have some flexible way to get power and water cooling to your work coil if you plan to heat stuck bolts.  Please keep us/me informed on how you do that. 

11
Well, it is finally up and running properly.
 Drawing about 4 amps idle current (still using 48 volt power supply), then goes to about 35 amps with crucible fully inserted.  Now need to mount a fan on the radiator and do a few other things.  Hate to say it, but I am not certain what caused the difficulties.  Later in my troubleshooting, I discovered that two adjacent turns of the work coil were touching, but separating them didn't help.  I took the fans off to get at the coil so I could insulate it with high temperature fiberglass sleeving.  When I put it back together, it works fine.
Maybe a cracked foil on the board?  Don't know for sure.

Next steps if it continues to work properly:
  Shoot for max current of about 40 to 45 amps.
Place fire brick below coil
  Try some steel  (to max out current) and to see how quickly it heats things to 1200° C.
1" Sq.
3/4" pipe  (pipe heats real fast since its a one turn "coil"
Melt some copper.
   Make a crucible cover. 
   Find/make tongs for pouring.
   Make a simple open face mold?


12
Yesterday I added a short lead to each gate of the Mosfets so I could scope them.  I didn't change anything else, but when I fired it up, the idle current is only  about 14 amps instead of the 26 amps that I had previously!  Then, when inserting the crucible, the current went up to  36 amps instead of the previous 40 amps.
 The gate signals are all pretty good looking square waves and they are all the same.
Why the change???---  I don't know, but all I did was to solder those gate leads in place.  Bad joints???

The aliexpress vendor didn't seem to pay any attention to my problem description.  They emailed me back to say:
"friend , can you tell us in aliexpress message ?"
Aliexpress customer service, by the way, seemed very concerned when I chatted with them about the issue earlier.  But all they did was to pass my concerns on to the vendor.

I did make a short video of the the above and may put it up on youtube as a troubleshooting aid.
If anybody who is viewing this message has one of these 1800 watt or 2500 watt ZVS heaters running, please tell me what YOUR idle current is.

Thank you,
Pete Stanaitis
---------------

13
Today I examined the heater by eye and with an ohmmeter.  Can't yet see any reason why the idle current should be so high.
   Circuit components are identical to the 1000 watt board, Just twice as many.  Except that there are 9 of the 0.33 ufd capacitors and a 10 turn 60+ mm ID work coil.
Stumped.
   I did see one video where the guy was testing an 1800 watt board with an ammeter in the ckt.  That's where I got MY "expected" 6 amps idle current from.  That and the fact that my 1000 watt heaters do about the same.
  I may try a smaller diameter work coil just to see what happens.
But I am still hoping for some sort of feedback from the vendor.  Chinese new year for 2019 (year of the pig) apparently does not start for a few weeks yet:
Jan 28 to Feb 19.
  I now see that I can get the gate signals from the bottom of the board, so I can look at them once I get my courage up.

14
i just checked the current by adding a direct reading ammeter in series with the shunt meter.  The readings are the same, within a couple of amps, since the scale on the new meter is fairly coarse.
  Haven't yet dismantled the board to look at circuitry, or to scope the gates.  The way this thing is made, you can't see inside much because the 4 heat sinks cover the sides and the fans cover the top.  when I do dismantle it, I probably should bring out a couple of test points.
I was hoping that I wouldn't have to dig into the thing at all.
No feedback from the Chinese vendor yet.  Is it Chinese new year right now?

15
Thanks for your question, flyrod.
  Yes, the chip IS the "LM2596HVS" version.
That makes the Chinglish warning about not using the converter when the input is over 36 volts even more confusing..
When I looked up the datasheet a couple of days ago, i googled "LM2596" and got this:
http://www.ti.com/lit/ds/symlink/lm2596.pdf
I didn't look beyond the first few pages when I found the max input voltage to be 45.
I even found another datasheet when it was spec'd at 40:
https://www.onsemi.com/pub/Collateral/LM2596-D.PDF

It didn't occur to me that to investigate the "HV".  Sorry, I hope I didn't cause too much confusion.  I guess I was biased by the warning that I mentioned earlier.
http://hmsemi.com/downfile/LM2596HV.PDF

  By the way, my buck converter doesn't have the pot.  There's a fixed resistor in its place.

I did fire the system up yesterday and it worked, BUT the idle current (current flow with nothing in the work coil) is at 26 amps.  I think it should only be about 6 amps.  It IS oscillating. When I put a graphite crucible into the work coil the current does increase to 40 amps.  Frequency is about 77Khz, by the way.
I have attempted to contact the vendor through aliexpress.  We will see how that goes.

For that initial test, I did add a radiator and  unplugged the buck converter and powered  the fans and pump from a separate supply, just in case.

Sorry for jumping to conclusions,
Pete Stanaitis
---------------


16
Hello, Mads.
I hope I am not getting ahead of myself here, but I see a new issue with both the 1800 watt and the 2500 watt versions of these ZVS heaters.
  It has to do with the little buck converter that runs the fans, and in the case of the one the I bought, the pump.
Here's what I have to say:
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
Important note if you intend to run your heater on 48 Volts:
You can NOT use the little power supply (buck converter) for the fans! You will have to provide a separate 12 volt supply at a couple of amps.
That is because the maximum rating of the regulator chip on the buck converter board is 40 volts. Don't ask me why they did that, but, hidden in the Chinglish, is a warning that operation at voltages higher than 36 will "burn" the fans and/or pump.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
I'm getting closer to powering the thing up.  I checked the no load current draw of the pump and its only about 300ma, but I will need to connect it to the actual system and fill it with water to see how much current it will draw,  Then, same for the fans.  Then find or make a simple power supply for them.

Have you noticed this situation, and what is your feeling about using that buck converter?

Pete Stanaitis
---------------

17
Good eye, Mads.
   Yes, I now see the extra heat sinks and additional pair of gate resistors.  So now it looks like 3 Mosfets in parallel on each side.
And I also now see that the 1800 watt model  has 90mm fans, versus the 120mm fans for the 2500 watt model..
I can only say that I did some  sloppy investigation!
I'll already updated  my pages to reflect this difference.

I will look forward to your comments when you get your board.
By the way, we have all heard the warnings about NOT connecting these zvs heaters directly to a switched mode power supply and then plugging the power supply in.  They say that the slow start characteristics of the SMPS cause it to start slowly and cause the mosfets to lock up.
And I am sure that is generally true.  But the server power supply that I got with my Aliexpress heater (Emerson 48-2900U Switched mode Power Supply)
doesn't even turn on until about 7 seconds after power us applied.  I will probably set my system up to power the supply first anyway, just to be safe.

(a bit red-faced),
Pete Stanaitis
   

18
I have been experimenting the the popular "12-48 Volt 1000 Watt ZVS Induction heaters" for a year or two and have many videos and web pages describing that work, as many of you may know.
   More recently, an improved version has become available and is being sold by well over a dozen vendors.  Instead of one pair of IRFP260N's driving the coil, they doubled up on them and added 2 fans on top.  The also added 50% more capacitance to the  tank circuit and increased the number of turns of the output coil from 7 to 10.  These tank changes should lower the oscillation frequency which is good for many things that people would want to heat.

  Just recently, I ordered one of them, a complete kit, called "Combo 2" by seller Aliexpress.
I had to wait quite a while for an analog ammeter and it’s here now.  I still haven’t connected it all up yet, but I have spent a lot of time unraveling the various  descriptions and pseudo instructions that I see on the vendor offerings.  These units are seldom soldi n as complete a kit form as the one the I got from Aliexpress.
Some vendors call them 1800 watt, some even call them 2500 watt, but I’m pretty sure they are all the same.
  Yesterday I put up a new web page to help new buyers understand what they just bought and how to set it up with a minimum of disappointment.
I tell you all this, because I’d like to get this link to others, since I am already getting inquiries anyway.
There are two web pages referenced here on this cover page:
 https://spaco.org/Blacksmithing/ZVSInductionHeater/ZVS1800Watt/1800-2500WattZVSInductionHeaterNotes.htm

Both pages are pretty messy, but, due to the apparent popularity of these devices, I wanted to get something out there.
Time will tell.

I will add to that page and to my youtube channel once I get my system up and running.

Pete Stanaitis
---------------

19
Getting a car battery:
  Many car batteries are replaced before they are totally shot.
Assuming that you do have a battery charger of some sort:
So, go to a car repair shop and ask if you can pick through their used batteries.  They get $5 or $10 in trade, right?  Prepare to pay that much.  If you tell them what you are doing with them, they may even sell them for less.
   Find one or two that still have some life left.  I know this is a rough "rule of thumb", but if the terminal voltage is above 12.2, it will probably take a charge, at least long enough for experimental purposes.

20
Quote
finding a 24V psu that can drive this thing is not easy or cheap.

Just add another 12 volt lead acid car battery.

Pages: [1] 2 3

* Recent Topics and Posts

post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
Today at 01:50:47 AM
post Re: Chinese MOSFETS/IGBTS
[Solid state Tesla coils]
Hydron
Today at 12:11:10 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
badpeter
March 22, 2019, 08:19:21 PM
post Re: Chinese MOSFETS/IGBTS
[Solid state Tesla coils]
profdc9
March 22, 2019, 06:39:37 PM
post Chinese MOSFETS/IGBTS
[Solid state Tesla coils]
Fumeaux
March 22, 2019, 05:51:55 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
March 22, 2019, 03:46:16 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
kamelryttarn
March 22, 2019, 11:25:19 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
Mads Barnkob
March 22, 2019, 10:56:16 AM
post Re: looking for PCB creating software
[Printed Circuit Board]
Teravolt
March 22, 2019, 06:02:15 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
badpeter
March 21, 2019, 11:04:48 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
Hydron
March 21, 2019, 07:51:23 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
badpeter
March 21, 2019, 07:09:05 PM
post Re: looking for PCB creating software
[Printed Circuit Board]
kamelryttarn
March 21, 2019, 02:26:09 PM
post Re: GDT Experiments
[Solid state Tesla coils]
Uspring
March 21, 2019, 11:57:53 AM
post Re: GDT Experiments
[Solid state Tesla coils]
Teravolt
March 20, 2019, 11:15:50 PM
post Re: GDT Experiments
[Solid state Tesla coils]
Thunderstruck
March 20, 2019, 09:07:04 PM
post Re: Keep or throw away ?
[Beginners]
Teravolt
March 20, 2019, 05:18:07 PM
post Re: New small SSTC
[Solid state Tesla coils]
Bambinz
March 20, 2019, 03:52:15 PM
post Re: New small SSTC
[Solid state Tesla coils]
Mads Barnkob
March 20, 2019, 01:23:52 PM
post Re: GDT Experiments
[Solid state Tesla coils]
T3sl4co1l
March 20, 2019, 01:18:29 PM
post Re: GDT Experiments
[Solid state Tesla coils]
Mads Barnkob
March 20, 2019, 01:06:24 PM
post Re: cute-qcw Tesla Coil
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
March 20, 2019, 01:00:46 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
Mads Barnkob
March 20, 2019, 12:41:22 PM
post Re: Keep or throw away ?
[Beginners]
Thunderstruck
March 19, 2019, 10:02:41 PM
post Re: Keep or throw away ?
[Beginners]
Hydron
March 19, 2019, 08:14:33 PM
post Re: Keep or throw away ?
[Beginners]
Teravolt
March 19, 2019, 05:12:03 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General chatting]
Experimentonomen
March 19, 2019, 01:32:32 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General chatting]
Mads Barnkob
March 19, 2019, 12:20:34 PM
post Re: Strange gdt waveforms
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
March 19, 2019, 12:15:22 PM
post Re: Which varnish to use to coat the Secondary?
[Solid state Tesla coils]
Mads Barnkob
March 19, 2019, 10:46:50 AM
post Re: Keep or throw away ?
[Beginners]
Thunderstruck
March 19, 2019, 09:11:09 AM
post Re: Keep or throw away ?
[Beginners]
Mads Barnkob
March 19, 2019, 08:24:31 AM
post Re: Keep or throw away ?
[Beginners]
Teravolt
March 19, 2019, 01:51:51 AM
post Re: Keep or throw away ?
[Beginners]
Thunderstruck
March 18, 2019, 09:56:42 PM
post Re: cute-qcw Tesla Coil
[Dual Resonant Solid State Tesla coils]
Weston
March 18, 2019, 07:55:52 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
March 18, 2019, 06:11:07 PM
post Re: Strange gdt waveforms
[Dual Resonant Solid State Tesla coils]
Hydron
March 18, 2019, 02:27:35 PM
post Re: cute-qcw Tesla Coil
[Dual Resonant Solid State Tesla coils]
Uspring
March 18, 2019, 12:52:35 PM
post Re: Strange gdt waveforms
[Dual Resonant Solid State Tesla coils]
FilipŠebík
March 18, 2019, 12:22:58 PM
post New small SSTC
[Solid state Tesla coils]
Bambinz
March 18, 2019, 11:46:18 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General chatting]
Bambinz
March 18, 2019, 11:29:02 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
Mads Barnkob
March 18, 2019, 10:35:04 AM
post Re: Strange gdt waveforms
[Dual Resonant Solid State Tesla coils]
Marty
March 18, 2019, 05:32:43 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General chatting]
Experimentonomen
March 17, 2019, 09:13:47 PM
post Re: DRSSTC Driver Logic
[Dual Resonant Solid State Tesla coils]
Netzpfuscher
March 17, 2019, 04:08:33 PM
post Re: WTB: Large Heatsink with a Baseplate at least 10mm thick
[Sell / Buy / Trade]
Phoenix
March 17, 2019, 02:46:44 PM
post Re: cute-qcw Tesla Coil
[Dual Resonant Solid State Tesla coils]
flyglas
March 17, 2019, 02:21:45 PM
post Re: DRSSTC Driver Logic
[Dual Resonant Solid State Tesla coils]
Laci
March 17, 2019, 01:54:47 PM
post Re: WTB: Large Heatsink with a Baseplate at least 10mm thick
[Sell / Buy / Trade]
Mads Barnkob
March 17, 2019, 10:15:16 AM
post Re: Which varnish to use to coat the Secondary?
[Solid state Tesla coils]
FilipŠebík
March 17, 2019, 09:33:50 AM