On Wednesday, December 9, 2015 at 1:31:33 PM UTC-5, Jan Panteltje wrote:> On a sunny day (Wed, 9 Dec 2015 10:01:19 -0800 (PST)) it happened George > Herold <gherold@teachspin.com> wrote in > <6c2345e7-04dd-415e-887d-7cc64bcc9ecf@googlegroups.com>: > > >> > >> http://www.ebay.com/itm/361287263867 > >> > >> This is the test setup: > >> http://panteltje.com/pub/inductive_heaTer_initial_test_setup_IMG_5190.JPG > >> > >> Using 3 of these set to 8 V in series: > >> http://panteltje.com/pub/meanwell_7.5V_20A_IMG_5189.JPG > >> > >> Works very nice, that is a backplate for a D connector for a PC that I use as mall for D connectors... > >> > >> No unexpected fireworks, no strange things, but I was very careful... > >> I tried solder wick with solder, that does not get hot. > >> I tried solder by itself and that does not melt, > >> need a metal or carbon container for a solder pot I'd think, > >> But great value for money, really cool gadget, 24 V battery on boat and you have 24 V cooking too. > >> (different coil) to bake eggs or fish, without converter, better efficiency. > >> > >> Fun:-) > > > >Thanks, I order one of these too, (but I still don't know how I'll power it.) > >Does it take the whole 20A at 24v? (I've got a 20V 10A supply.) > > I think not, but of course it depends on the load. > I left out the amp meter as I was worried the extra lead resistance would drop the voltage too low. > Maybe you did see the youtube video of the guy who blew one up? > > So this is my take: > 1) Check the copper pillars on the board, the screws are too long, or the thread in those too short, > replace or cut so it actually is fixed to the board, avoid bad contacts. > 2) Create spacing between the turns of the coil, mine were packed close and touching, else you get shorted turns. > 3) Do not use a slow ramp power supply, I switch on supply and _then_ connect the circuit. > 4) Do not start it with a load already in the coil, as then it may not start oscillating and blow a MOSFET.Yup, that all makes sense.> > > > >I like the idea of two car batteries in series... > >"Sorry honey no car today, we're induction heating" > > 2 11.1 V RC lipos should work too. > > > >Maybe with a current meter in series? > > Yes, contemplating how to build this into some box I ordered this: > http://www.ebay.com/itm/181938789895 > cannot make it for that money, see circuit diagram at bottom page.Wow that is cheap. I've got some old Hoyt galvanometer/ ammeters. I was thinking a current shunt acorss one... but the 5 milli ohm shunt is a dollar or two. George H.> > > > >George H. > >
Steel melter for forty bucks? Needs a KW dc supply. Also $1 100nS 30KV! Also ALSO!
Started by ●November 21, 2015
Reply by ●December 9, 20152015-12-09
Reply by ●December 9, 20152015-12-09
On Wednesday, December 9, 2015 at 6:51:04 AM UTC-8, Jan Panteltje wrote:> No unexpected fireworks, no strange things, but I was very careful... > I tried solder wick with solder, that does not get hot. > I tried solder by itself and that does not melt, > need a metal or carbon container for a solder pot I'd think, > But great value for money, really cool gadget, 24 V battery on boat and you have 24 V cooking too. > (different coil) to bake eggs or fish, without converter, better efficiency.On the actual induction cooker instructions they say FERROUS PANS ONLY. The induction hotplate has a magnetic sensor, and won't turn on for aluminum fry-pans. Probably the resistance of iron is high enough to match, while aluminum or copper behave as an EM shield rather than as load. Heat up a steel bolt and melt? So, solder pot = iron pipe cap ?
Reply by ●December 9, 20152015-12-09
Den torsdag den 10. december 2015 kl. 00.42.11 UTC+1 skrev Bill Beaty:> On Wednesday, December 9, 2015 at 6:51:04 AM UTC-8, Jan Panteltje wrote: > > No unexpected fireworks, no strange things, but I was very careful... > > I tried solder wick with solder, that does not get hot. > > I tried solder by itself and that does not melt, > > need a metal or carbon container for a solder pot I'd think, > > But great value for money, really cool gadget, 24 V battery on boat and you have 24 V cooking too. > > (different coil) to bake eggs or fish, without converter, better efficiency. > > On the actual induction cooker instructions they say FERROUS PANS ONLY. > The induction hotplate has a magnetic sensor, and won't turn on for > aluminum fry-pans. > > Probably the resistance of iron is high enough to match, while > aluminum or copper behave as an EM shield rather than as load.the resistance of iron is 7x that of copper, the skin depth of iron is also ~1/40 of copper so the resulting resistance gets much higher> > Heat up a steel bolt and melt? > > So, solder pot = iron pipe cap ?that's what the guy in the you tube video did, he also managed to melt aluminium in a graphite crucible -Lasse
Reply by ●December 10, 20152015-12-10
On a sunny day (Wed, 9 Dec 2015 15:42:04 -0800 (PST)) it happened Bill Beaty <billb@eskimo.com> wrote in <6cd393a5-d56b-40df-bce7-33cfdb223ca3@googlegroups.com>:>On Wednesday, December 9, 2015 at 6:51:04 AM UTC-8, Jan Panteltje wrote: >> No unexpected fireworks, no strange things, but I was very careful... >> I tried solder wick with solder, that does not get hot. >> I tried solder by itself and that does not melt, >> need a metal or carbon container for a solder pot I'd think, >> But great value for money, really cool gadget, 24 V battery on boat and you have 24 V cooking too. >> (different coil) to bake eggs or fish, without converter, better efficiency. > >On the actual induction cooker instructions they say FERROUS PANS ONLY. >The induction hotplate has a magnetic sensor, and won't turn on for >aluminum fry-pans. > >Probably the resistance of iron is high enough to match, while >aluminum or copper behave as an EM shield rather than as load. > >Heat up a steel bolt and melt? > >So, solder pot = iron pipe cap ?Yea, some experiments coming up over Christmas I'm sure. First thing I want to build in is a protection against power failure and then power slowly coming up, was thinking about a big thyristor: thyristor + -----------|>|---- load | \ |--||-----\ -- | | button --==-- R Normally when power rises, the thyristor is off. Press the switch (moment) and C discharges into the thyristor gate and you have power. If power fails then comes back the things stay off. And 20 A thyristors plenty.. but it drops some voltage. But indeed if I want to add some features then a simple MOSFET in the supply gives better control. There is a long list of experiments, and experiments one should NOT do ammo no. magnesium sheet? Pity I no longer have that helium neon laser tube. Will think of something:-)
Reply by ●December 10, 20152015-12-10
On a sunny day (Wed, 9 Dec 2015 12:12:45 -0800 (PST)) it happened George Herold <gherold@teachspin.com> wrote in <664960a5-ee57-46b3-a177-6149d9bc1ec6@googlegroups.com>: I have been experimenting with different materials today. This youtube video (cannot understand the language) has some scope shots: https://www.youtube.com/watch?v=5V2VJf6cBI8 it shows with those coil spacings the frequency is about 100 kHz, and lowers under load. I have bend the coil turns a bit outward, so probably higher, will measure it later. Also I ordered (big spending) a carbon crucible: http://www.ebay.com/itm/321849233116 The smallest one... I noticed I can get solder to sort of melt by making a loop (one turn), same for putting solder wick in a loop. Alu strip does not even get hot, it seems the stuff has to be either magnetic, or form some sort of turn. maybe that is why the crucible gets hot??? Carbon rod (from pencil) stays cold, but maybe it is not really carbon. I have one real carbon rod left that I used for magnetic levitation that I do not want to offer. http://panteltje.com/pub/levitation_cut_img_3051.jpg Real carbon rods seem hard to find, old 1.5 V batteries had those. Made a crucible from a big iron bolt with 2 nuts on the end, that works. Better use a stone or something to do the experiment on :)
Reply by ●December 10, 20152015-12-10
And here is a even cheaper version at 5 MHz: https://www.youtube.com/watch?v=NcU3f29fmc8 circuit diagram: http://4hv.org/e107_files/public/1343151826_4152_FT142264_3243_1343150063.jpg_206.jpg That is a lot like what I did in the sixties, but then with tubes and a real driver (also tubes). But it shows that it does not have to cost a lot. I am still looking around on the web what others have done using induction heating. Finding all sorts of interesting things. Of course at 5 MHz or so you need to be aware of any RFI you cause. I killed transistors laying next to it in a box metal that way. But 4 sure a low budget solution.
Reply by ●December 10, 20152015-12-10
On a sunny day (Tue, 08 Dec 2015 16:15:43 GMT) it happened Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> wrote in <n46vnk$57h$1@news.datemas.de>: After some thought and the realization that the heat is generated by current induced in a shorted turn, I got a metal cap from a Bertolli olive oil bottle, mind you remove the plastic washer first, this cap seems to be made of thin aluminum? Good green paint too (hope it is not whatsit? cadmium based), and YES, solder melts in TWO to THREE seconds! http://panteltje.com/pub/melting_solder_in_an_metal_olive_bottle_cap_IMG_5191.JPG Tomorrow (tm) I will fill that cap with solder and run again. Now how's that for cheap? Apart from the whole house stinking of burned olive oil and -plastic yes that seal. 3 seconds, my goodness.... And the solder does not even stick to that cap.
Reply by ●December 10, 20152015-12-10
On Thursday, December 10, 2015 at 11:18:46 AM UTC-8, Jan Panteltje wrote:> Tomorrow (tm) I will fill that cap with solder and run again. > Now how's that for cheap?Speak of cheap, before paying for carbon crucibles, instead buy blocks of bulk graphite by the pound. Chop it into tiny cups using a power saw and dremel tool. (I haven't tried this yet. But carbon cruicibles are probably just graphite.) ebay Search: graphite block glass ebay Search: edm graphite Or, I find $3 for 40mm graphite cup: http://www.ebay.com/itm/7-OZ-Pure-Graphite-Crucible-Cup-Propane-Torch-Melting-Gold-Silver-Copper-30x40mm-/321828640195
Reply by ●December 11, 20152015-12-11
On a sunny day (Thu, 10 Dec 2015 14:11:06 -0800 (PST)) it happened Bill Beaty <billb@eskimo.com> wrote in <e9df4df7-a64c-44c9-8932-49b29812b6f1@googlegroups.com>:>On Thursday, December 10, 2015 at 11:18:46 AM UTC-8, Jan Panteltje wrote: > >> Tomorrow (tm) I will fill that cap with solder and run again. >> Now how's that for cheap? > >Speak of cheap, before paying for carbon crucibles, instead buy >blocks of bulk graphite by the pound. Chop it into tiny cups >using a power saw and dremel tool. (I haven't tried this yet. >But carbon cruicibles are probably just graphite.) > >ebay Search: graphite block glass >ebay Search: edm graphite > >Or, I find $3 for 40mm graphite cup: > >http://www.ebay.com/itm/7-OZ-Pure-Graphite-Crucible-Cup-Propane-Torch-Melting-Gold-Silver-Copper-30x40mm-/321828640195I already ordered one, see my other posting in this thread, but as that takes weeks sometimes to arrive, wanted to test the shorted loop theory. Need some mechanical temperature control, maybe have a RC servo move the crucible in or out, or simpler move the coil up or down over it. ^ []IR temp meter | [servo }-------[ ] coil \./ crucible with solder something like that perhaps.
Reply by ●December 11, 20152015-12-11
Found a better crucible, it is the alu cap that holds the spring from the soldering stand of my LS50 soldering station. :-) That cap is not needed (it never catches any solder anyways), so now tried it with some more pieces of solder scrap I found: http://panteltje.com/pub/inductive_heating_better_crucible_IMG_5195.JPG A little more than a minute and a half or two before it all was very fluid, stuck a copper wire in it.. It stays fluid quite long (minutes). Tried to tin some wire with mixed results, this solder was not very clean an 60/40 mixed with silver ROHS stuff, plus some plastic I guess, and dirt. But it works. I was sort of expecting as the cup filled up, that the part that forms the 'shorted turn' that creates the heat, to become smaller, and this seems to give an automatic temperature stabilization? I mean if it is full there is no more shorted turns, provided the solder makes good contact. need to really measure current.
