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Induction brass annealer redux

Thanks. I'm working on a build with a 40A 48V supply, 2kW induction board. Looks like this device is rated 21A. Can you suggest an option that can switch 40A?
In fact the main reason for the larger induction board is to derate the capacitors for continuous use, so I guess I could current-limit the supply, but it would be interesting to have the capability to switch the full load.

IGBT's can be had all the way to about 200A. But there's no reason you couldn't use several in parallel, SSR's and half bridge/dual half bridge drivers do this all the time.

Here's a 100A continuous @ 25C, 50A @ 100C unit-

https://www.mouser.com/ProductDetail/Infineon-IR/IRG6B330UDPBF?qs=cPwVhw1VIU41FQ4YgjhpNA==

Not saying this will fit your goals perfectly, there's lots of choices out there, take a peek at the specs. And it looks to me like a big heatsink is in order, 200w heat dissipation.

But honestly, the simplest solution is a good relay, big HD transistor vs. an SSR is just another option for the tinkerer's out there.
 
IGBT's can go really big. I had a fair bit of experience with them in Uninterruptible Power Supplies they would switch the 400V DC of the batteries to recreate an AC waveform. Wish I was still in that field just now so I could get my hands on some of them and other bits in there.
 
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If you want a simple solution I'd try this relay. I have one but it's big and overkill for the regular Gina/Erick annealer design. It comes in 12, 24 vdc coil or 120 , 240 vac coil. It doesn't sound cool like SSR set for take off but it probably won't go into a flat spin and crash and burn either. It's really not that big..but it does have some heavy serious duty contacts....About $15.00 but it's worth it.....HB


https://www.ebay.com/sch/i.html?_fr...leDesc=0&_osacat=0&_odkw=super+duty+relay+12v
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Plus you get that cool "click-clack" noise as your annealing :)
 
Plus you get that cool "click-clack" noise as your annealing :)

That's a good point!

For the sake of saving a single component, IGBTs seem to bring a heat problem & SSRs a cost problem. I guess I'll stick to a BJT* and a mechanical power relay. I'll monitor PSU current over the network to detect a contact weld and kill the mains supply.

* or should I be using a FET (driving a relay coil from Arduino output)?
 
I suspect they are right. The colour change you see seems to differ from brass to brass and on how clean it is etc. I'd place more faith in Tempilaq melting/discolouring at the point on the side wall you want it to. I don't think anyone here knows what the right point is. If you induction anneal in darkened room you will see the case mouth rim glow first and this glow shoot down the mouth of the case just prior to drop. I understand an orange glow on brass is circa 1000F. Whether any of this makes a difference or is optimal annealing I haven't the faintest idea but it is fun to build the annealer and use it. :)

Hi SGK I see you have mentioned seeing a very quick red glow on the case mouth and down the neck. In experimenting with the 750 Tepilaq looking at how it changes and trying to decide if a change has in fact made that part of the case anneal or not. anyway the Tempilaq changes state or colour in the same fashion stating at the case mouth and then quickly moving downwards. I watched this happen in a dark room and had the templiaq change but no glow changed the time and then saw the very quick red glow of the neck. This gave a nicer factory look on the case. However I am very concerned about the change of colour in the brass. The induction heater puts so much power into a very concentrated area. Which is what we want. Having the brass change coulour in the neck to this red IMHO is bad the brass has got too hot.

I will be sneaking up on it watching the Tempilaq and also the dark room so as not to get a change just like you don't want a bright red glow when using a flame. Much harder with these induction heaters has the time is compressed probably by 20*
 
I find it interesting that BROWNELLS "Serious about firearms since 1939" only sells Tempilaq in 650 and 700 for the brass annealing. So a few months ago I bought the 700 they offer and have used it and adjusted my annealers to that temp on my various brass. So whatever is going on with 700 Tempilaq on my brass it seems soft and very easy to work with resizing. I don't always get the pretty color on some brass but it has definitely gone soft. Someone on another thread said full anneal / dead soft is too soft and would ruin the brass anyway for re-use. I think BROWNELLS knows something here, at first I was irritated they didn't offer 750 tempilaq. Now I'm ok with it. Time will tell, I've got a lot of 6.5 reloads going on now.
 
Whether its a MOSFET/SSR/IGBT or whatever you'll still have heat to dissipate due to the voltage drop across the collector/emitter when at 100% duty cycle. TAANSTAFL. A single TO-247 sized transistor capable of sinking 100A @ 25c @ 15v is a pretty darned stout switch.

I might try one for giggles in the near future, the max gate voltage on the big ones is compatible with my 12v analog setup, and I have some big TO-220/24x/26x heatsinks somewhere from another project. A liquid cooling block would be very easy to implement (and probably unnecessary).

You could use just about any cheap through hole NPN transistor to drive the DC relay coil via a microcontroller. 100mA is more than big enough for a std relay actuator coil.

That's a good point!

For the sake of saving a single component, IGBTs seem to bring a heat problem & SSRs a cost problem. I guess I'll stick to a BJT* and a mechanical power relay. I'll monitor PSU current over the network to detect a contact weld and kill the mains supply.

* or should I be using a FET (driving a relay coil from Arduino output)?
 
These use to work ok with B Stamps a few years ago. Wouldn't think the I/O's changed that much since then. The ole reliable 2n2222 is good for 400-500 ma max (not continuous long term). These bigger coils draw 90 ma. Beware of many solenoids on EBAY that say 300 ma for your trap doors they may pull 900ma to 1100ma, they lie, or simply don't test them. If your flavor is a PNP try a 2n2907 it's the equal to the NPN 2n2222

Then you have the Fet drivers that are so cheap on Ebay / Amazon made for your Arduino.

https://www.ebay.com/itm/MOSFET-But...=item33fd53e1e1:g:T40AAOSwnH1WbE8h:rk:34:pf:0
 

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Watch out for the collapsing current capability it rising temperature. Always check the SOA chart first and go through the calculations with regard to heat generation and dissipation.

You can now find quite good current capable MOSFETs with very low Rds(On) and so much lower heat generation as a result. Of course the challenge there is achieving positive Vgs to turn the Mosfet on when high-side switching. There are plenty of drivers around to do this however.
 
I am really procrastinating my biggest issue ATM is of what type construction to build a box out of. I have the same shape as @dskogman used on page 33 in my mind gauges and switches on an angle set back from the front plate. I was going to use the concrete formply which is good heavy plywood about 17mm thick. I am just thinking the thing will weigh a ton if I do use that. I just made some battery and computer boxes for the Rifle club out of it they weigh heaps very strong structurally. Have gone through the thread many times the computer cases look good just not my envisioned shape too high. Thinner ply like marine ply is an option more expensive but thinner and lighter. Will it be thick enough without an inside timber frame?
 
That should be more than strong enough. I built mine with 1/2” MDF as a prototype with the intention of building a finished version with better plywood. Never got around to it and it works fine.
 
I made my Gina with a 1800W induction plate and 46V ( 53W actually ) supply, but it is too hot. My Lapua 308 Win Brass melt in just 4 seconds.
How can I reduce the heat:
Inserting a resistor to reduce the supply's power or increasing the coil diameter?
 
Reduce the Voltage as much as you can. Increase the coil diameter. did you make the coil as per the specs here? I am surprised using a 1800W unit actually made a difference. I thought the 1000W unit was not actually limited in its ability to deliver power as by its own specs as there is no limiting. It is all done by case insertion depth and the coil size.
 
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Not the former - the resistor would have to dissipate an enormous amount of heat
Reduce the Voltage as much as you can. Increase the coil diameter. did you make the coil as per the specs here? I am surprised using a 1800W unit actually made a difference. I thought the 1000W unit was not actually limited in its ability to deliver power as by its own specs as there is no limiting. It is all done by case insertion depth and the coil size.

I increase the coil diameter to 1.2 inches and works great now.

Thank you!
 
I increase the coil diameter to 1.2 inches and works great now
@chuckswagger Please clarify. You posted that your original coil would melt your 308 cartridge in 4 secs. I realize that melting the brass is going way past the anneal temperature we're targeting, but with your original coil were you still overshooting your target annealing temp at say 1-1/2 to 2 secs?
Also just trying to get an apples to apples comparison what was the inside diameter of your original coil? (looking for a comparison to the standard design of 1-1/8" inside diameter)
 
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The PS needs to be at 20v plus and the power needs to hit the board quick or the tank circuit will not start 'ringing' and the board will blow up (mosfets mostly). Lots of videos of people blowing up these boards trying to test them with a 12v or 18v battery, or using a test PS and trying to 'ramp up' slowly. The 'quick' part can be accomplished by either an SSR or a std coil and contact relay.

I tried using the switching function built into the RSP-750 PS and this was a complete fail as the PS tries to ramp up the output voltage and current slowly, fortunately for me the limiting features saved the board, the PS outputs shut down immediately.


I don't know if it makes a difference electrically but I chose to use the relay on the negative leg of the board only, I'm not sure there is any benefit at all to using a relay pole on both the + and negative sides, other than if one sticks or fails to release the other will. Maybe a real EE could chime in here.

Hey GrocMax,

Bit late in the thread, but wanted to say thanks for the response - I think the DPS may run into the same issue as your PSU, so haven't risked trying.

Stuck with the SSR and using an arduino to switch that on a timer for annealing.

Now I just need to work out what kind of case I'm going to make/use

ATB

Tim
 
There is a new 1800 watts board on the market. What would be a suitable Power Supply with adjustable voltage/power?
The current 1000 watts board works continuously only at 500 watts with 750 watt Mean Well Power Supply. Trying to anneal bigger brass.
 
I really dont think the larger power boards and power supplies to match are necessary. I have built a couple of different units and done some modifications which I will post about shortly. Still putting the data and story together. But in a nut shell with a case fully in the work coil (which may not be a good position as to much of the case gets heated). There is a maximum amount of current that will be drawn and this may be less (most likely) than the 1000W board can deliver. I made some mods to get it to deliver more current as it maxed out at only 12A it can handle 20A easily I had a 48V 1500W power supply. This was not really needed.
So what brass do you want to anneal?
 

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