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Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1343

Posted: 02:48am 27 Sep 2024

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G'day Guy's,
Well I got this Temu induction heater for $49 just to have a play,

Now the supplied coil was under 40mm internal diameter and just too small so I first made a 4" diameter coil then changed it to a 3" diameter coil.

I used a an old machining project as the crucible and found it only get to around 460C and stays there. Did some quick research and soon found the circuit so upgrading this is going to be needed.

Now with crucible in it was drawing around 340 watts and I do think we need to get around 1Kw to get the crucible over 1000C to melt copper.

This is the circuit and I do have a heap of HY5608 fets and looking at those small chokes from the aerosharp they are 0.5 mH for the caps ordered 20 of those to use as the cap bank.

Here is a pic of the setup

I have found any metal below the coil so I cast some refractory cement into a tin can and with this morning trial the tin is heating up so I'll take the can off and just have the refractory block. So the heatsink issue can be fixed.

I did look at this many years ago and guy's were doing the same thing as the ZVS oscillator is the electric version of a small forge.

Regards Bryan

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2134

Posted: 04:12am 27 Sep 2024

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Insulating the crucible may be all you need to do.
Cast a refractory cement cylinder to fit between the coil and the crucible.

Make formers from thin cardboard or stiff paper wrapped loosely around the crucible and inside the coil.
Mix the cement with plenty of sawdust. When the sawdust burns out it leaves voids that improve the insulation.

As you have already observed keep it well away from metal when running by sitting it on a brick or cement block.

When trying to melt wire rather than a solid lump you may need to improve the RF coupling by winding it into a multi layer coil with the turns parallel to the drive coil, and the ends twisted together.
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Edited 2024-09-27 14:24 by phil99

Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1343

Posted: 06:01am 27 Sep 2024

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Hi Phil thanks for that tip on insulating the crucible and I did find a Coopers Lager beer can was just the right size for a former so the refractory cement cast is done. I just put a 5/8" nut under the crucible to raise it and tomorrow when it's done I'll peel off the can and get the crucible out. Also I put some sawdust in as per your suggestion and I found a brick the right height to sit under the coil.

I did try everything I know to get that 20x4 LCD working on that RP2040 Zero but everytime it came back with the error of the LCD not open did my head in so a change of tack was needed. I was surprised just how quick those RP2040camera boards got processed and they have shipped already.

Now I do have 1.5Kg of tin coated copper from an old job I did where I kept the billets from punching holes in an ironworker so I'll have to come up with an idea for a bronze project when this unit does it's job.

Regards Bryan

Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1343

Posted: 07:48am 27 Sep 2024

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As I had a couple of powdered iron toroids here decided to wind 35 turns of 1.6mm and found out it was 12mH so kept unwinding turns and ended getting down to 5 turns for 232uH so going 3 inhand for 5 turns should get me around 70uH and shouldn't get too hot when in use.

Now silly me ordered 0.47uf caps instead of 0.047uf so I reckon 10 in series in 2 strings will get down to around 0.47uf.

There's a pic of the cast in the coil and it fits in nicely with plenty of headroom so I'll give it another run in the morning after I get the cast stripped.

Regards Bryan

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2134

Posted: 07:56am 27 Sep 2024

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Page 41 of the current manual lists which LCDs work with MMBasic.

Paste the bits of your program that setup / use the LCD here, or on the Micro controllers page (more LCD experts will see it there).

Quote LCD Display
The LCD command will display text on a standard LCD module with the minimum of programming effort.
This command will work with LCD modules that use the KS0066, HD44780 or SPLC780 controller chip and have 1, 2 or 4 lines.
Typical displays include the LCD16X2 (futurlec.com), the Z7001 (altronics.com.au) and the QP5512 (jaycar.com.au). eBay is another good source where prices can range from $10 to $50.

To setup the display you use the DEVICE LCD INIT command:
DEVICE LCD INIT d4, d5, d6, d7, rs, en
d4, d5, d6 and d7 are the numbers of the I/O pins that connect to inputs D4, D5, D6 and D7 on the LCD module (inputs D0 to D3 and R/W on the module should be connected to ground). 'rs' is the pin connected to the register select input on the module (sometimes called CMD or DAT). 'en' is the pin connected to the enable or
chip select input on the module.
Any I/O pins on the PicoMite can be used and you do not have to set them up beforehand (the LCD command automatically does that for you). The following shows a typical set up.

To display characters on the module you use the LCD command:
DEVICE LCD line, pos, data$
Where line is the line on the display (1 to 4) and pos is the position on the line where the data is to be written (the first position on the line is 1). data$ is a string containing the data to write to the LCD display. The characters in data$ will overwrite whatever was on that part of the LCD.

The following shows a typical usage where d4 to d7 are connected to pins GP2 to GP4 on the PicoMite, rs is connected to pin GP6 and en to pin GP7.

DEVICE LCD INIT GP2, GP3, GP4, GP5, GP6, GP7
DEVICE LCD 1, 2, "Temperature"
DEVICE LCD 2, 6, STR$(TEMPR(GP15)) ' DS18B20 connected to pin GP15

Note that this example also uses the TEMPR() function to get the temperature (described above)

Edited 2024-09-27 18:00 by phil99

Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1343

Posted: 09:09am 27 Sep 2024

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Hi Phil I did use those exact lines of code, now I did the DEVICE LCD INIT on the commandline and when I made a simple program where I just used the DEVICE LCD 1, 2, "sleeping" came up with the error Not in Use.

Now after I did a reflash trying to do that LCD init came back with the error GP1 isn't a input so moved everything one pin over only to find GP2 isn't a input went all the way to to GP10 and it still wouldn't work.

When I first setup the text did appear and trying a DEVICE LCD CLEAR came back with not Open error. After that nothing worked so I did think time for a break. I did do a post on this on my SSD1963 thread but it's gone unanswered.

Now numerous times you have put up that tweak you use for searching this forum but silly me has never written it down. The search function on this forum for me just doesnt work

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2134

Posted: 12:26pm 27 Sep 2024

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In your browser search bar type:-

site: thebackshed.com "your search terms"

The quotes are optional, but they seem to make the search more specific.

Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1343

Posted: 03:21am 29 Sep 2024

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G'Day Guy's, Well took Phils suggestion and made another coil to sit inside the copper coil. Silver brazed the connections and gave it a run.

Well the 15 amp fuse popped so put a 30 amp fuse and that one popped so put another 30 amp fuse and used my clamp meter and 64 amps was being drawn. The 30 amp fuse soon popped so found a 63 amp fuse

Not thinking on the size of the wire about 5 minutes into the run lets just say the cable let out the magic smoke and lots of it

So cut the negative wire coming from my shed battery and looks like I'm going to have to move it closer to the battery due to the current drawn.

I welded on a handle so the crucible can placed and removed easily. Now with these duel coils I'm thinking it may be too much for this Temu board so when I get back from holidays I can on making the new heavier duty one.

Regards Bryan

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2134

Posted: 03:47am 29 Sep 2024

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It seems I failed to explain properly what I meant.
I the photo the copper you wanted to melt in the crucible was bunched up vertically. That will absorb the RF energy poorly, So wind it into a coil (with the ends shorted) that just fits in the crucible with the turns parallel to the RF coil.

Having two RF coils in parallel is obviously overloading the oscillator.

Put the refractory cement insulator you made between the crucible and the original coil.

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