DIY Induction Heater Builds and References

[TommyDee]

You've got the circuit correct @blastfromdapast - the 5-amp switch could be under the limits but that depends on power supply and the final configuration. 60 watts is 12V at 5A. I can pull 80-90 watts on several caps if I give it the juice. Will the 5 amp switch work? sure - but if you are pulling more, it might fail at some point. Always nice to have a way to measure power input to know how the unit is operating.

 

[blastfromdapast]

You've got the circuit correct @blastfromdapast - the 5-amp switch could be under the limits but that depends on power supply and the final configuration. 60 watts is 12V at 5A. I can pull 80-90 watts on several caps if I give it the juice. Will the 5 amp switch work? sure - but if you are pulling more, it might fail at some point. Always nice to have a way to measure power input to know how the unit is operating.

thanks so much for this quick reply. I am raring to go and get it done. This is fun!

Doug Baird

 

[badbee]

5Amp 250VAC

Keep in mind that a switch rated for 5 A AC is only good for about 2 A DC. Switches in DC circuits experience more arc'ing as the switch opens, with an AC circuit the arc is broken when it swings through zero volts. This is low voltage but you still want a good solid switch with the required DC rating.

 

[blastfromdapast]

Keep in mind that a switch rated for 5 A AC is only good for about 2 A DC. Switches in DC circuits experience more arc'ing as the switch opens, with an AC circuit the arc is broken when it swings through zero volts. You want a good solid switch with the required DC rating.

thanks, I ordered some automotive ones, that should do the trick. Not fancy nor do they light up but solid.
Thanks again

Doug Baird

 

[Darkcrusade1]

@TommyDee would you be able to shed some light on this setup? This seems very enticing for compact 18350 3S setups. I'm unsure on the wire that splits the inductor and how the capacitor is ran through to connect. I'm assuming the board had been drilled through, but also noticed a different wire setup below. I can't understand where switch and power would run in. HalfPint is amazing and this particular setup seems like the most superior for compact setups.

 

[TommyDee]

I don't have that one with me at the moment. It follows 'principles' of the other HalfPint builds. It just show a different aspect of component orientation.
For reference, the switch trace cut was done at the switch in the image, near the connector. The cut is replaced with a micro-switch for activation.
The inductor was wound with 18gauge magnet wire. The common leg was brought out for + input power.
I drilled holes for the cap.

It all fit within the envelope. Hey @mecrobs - you still got this thing handy?

 

[roontoon]

Hi newbie here and I am interested in building a half-pint and I have a question. In the other DIY IH I have seen have a Mosfit as part of the build. Do you have a schematic that you can share? Thanks.

 

[TommyDee]

Halfpint is two innovation - 1) reducing the component bulk and 2) removing the MosFET switch. Let me know if you want me to make sense of what the trace cut does. The cut is where the "M" switch is located. Don't pay too much attention to the existing data as much of it is out of date but properly connected.

 

[roontoon]

So you are not using a ZVS board? Or are you building one?

 

[TommyDee]

The original schematic represents the standard ZVS board. That's why I say to ignore much of the written information. I added the switch that represents the cut on the standard ZVS board that separates the drive circuit from the power circuit.

 

[roontoon]

Ok got it. So battery and switch wiring and you're good? Or are there other modifications I should know about?

 

[TommyDee]

Each trick for HalfPint is independent. The trace cut allows a low power momentary switch for firing on either a full module or HP module; The inductor 'sharing' (two chokes on a common core) is the other trick along with removing a capacitor for the purposes of component reduction.

 

[roontoon]

So the momentary switch is across the two sides of the trace cut. Is there some info about the chokes and the capacitor hack? Thanks

The inductor 'sharing' (two chokes on a common core) is the other trick along with removing a capacitor for the purposes of component reduction.

 

[TommyDee]

A few pages back is a detailed choke mod.

The cap is just removing one of the caps. This is in line with an observation made by Chris of DynaTec in his artisan days in essence saying the standard ZVS module is too powerful (and it is) and where Pipes provided the option of clipping the capacitor's leg on his Caldron or PSM to tame the heater.

DIY Induction Heater Builds and References

Box Troll Alright; we're gonna fuck with the Box Troll above. We will be doing a comprehensive build of one version of HalfPint, this being the flat version with components on the opposite side. I have made this decision based on several factors in no particular order; 1) The light will be...

fuckcombustion.com

Oh, and yes, the momentary switch bridges the trace cut for activation (providing 12V to the driver circuit).

 

[roontoon]

A few pages back is a detailed choke mod.

The cap is just removing one of the caps. This is in line with an observation made by Chris of DynaTec in his artisan days in essence saying the standard ZVS module is too powerful (and it is) and where Pipes provided the option of clipping the capacitor's leg on his Caldron or PSM to tame the heater.

DIY Induction Heater Builds and References

Box Troll Alright; we're gonna fuck with the Box Troll above. We will be doing a comprehensive build of one version of HalfPint, this being the flat version with components on the opposite side. I have made this decision based on several factors in no particular order; 1) The light will be...

fuckcombustion.com

Oh, and yes, the momentary switch bridges the trace cut for activation (providing 12V to the driver circuit).

Thanks

 

[roontoon]

Any recommendations on the type of battery to get in terms of amperage and capacity? Flat or button top?

 

[TommyDee]

I did a custom 3D printed 18350 case. 1200mah (or thereabout) is having a great run in my Flites and home built. These are great for size.
I tried 14500 and they suck! They cannot handle the load no matter what the rating. They unbalance within a few weeks.
Then you have Lipo packs in all shapes and sizes - nothing wrong with this option. Very space efficient; and they tend to exhibit lower internal resistance meaning they will deliver a higher voltage than a similar Liion. BMS wires up similarly and works as a charger so no big change. I think Lipo get a bum rap.

If you are fortunate enough to have, or run across, some of the older caps, the IH can draw as much as 8 amps. I've configured coils to pull well into 100 watts meaning 12V and 8+ amps. Newer caps are wimps and might draw 4-5 amps. I like to design for 8 amps but I might tune more aggressively if all the IH will see is these weaker caps. The days of hot caps are gone as far as I can tell. During the tune, you are aiming for 60-70 watts for your favorite cap. 60 is good for flavor and gentle bakes where 70 watts can get you a heavier hit but still a well managed bake.

As to how fast the bake is - forget it. Aim for 8-10 seconds for the goodies to come out of your bud. This will make sure that most caps will behave similarly. Otherwise, you are just fooling the clicker without any useful temperature reference at the click.

Capacity - Aim for 1WH/bowl. Minimum 400mwh/bowl. I can get to the click at 150mwh, budget 200-250mwh/click. For me, a true 1,000mah 3S works for me as heavy daily use. 18650 will make it much more capacity but I find them bulky and heavy. I haven't done a 2S 18650 to see what if would take. Consider the low voltage performance at 6V/9V. These should still be useful.

 

[webtroter]

If you are fortunate enough to have, or run across, some of the older caps, the IH can draw as much as 8 amps. I've configured coils to pull well into 100 watts meaning 12V and 8+ amps. Newer caps are wimps and might draw 4-5 amps. I like to design for 8 amps but I might tune more aggressively if all the IH will see is these weaker caps. The days of hot caps are gone as far as I can tell. During the tune, you are aiming for 60-70 watts for your favorite cap. 60 is good for flavor and gentle bakes where 70 watts can get you a heavier hit but still a well managed bake.

Does the tip has an effect?

I knew caps were different, but I didn't think the effect was this big with an IH. I thought the tip had a greater effect on the heating.

 

[TommyDee]

@webtroter - The cap actually shields the tip from interaction with the induction heater. If it is 10% involved, it is too much. Hotter caps really do make a difference in rip density. It comes with challenges too, of course - much easier to combust.

 

[roontoon]

Capacity - Aim for 1WH/bowl. Minimum 400mwh/bowl. I can get to the click at 150mwh, budget 200-250mwh/click. For me, a true 1,000mah 3S works for me as heavy daily use. 18650 will make it much more capacity but I find them bulky and heavy. I haven't done a 2S 18650 to see what if would take. Consider the low voltage performance at 6V/9V. These should still be useful.

How do you measure the WH and/or change the values to be suitable?

 

[TommyDee]

Those are both very loaded questions - the first is easiest; I used one of the cheap digital power supplies w/ a meter on eBay that has all kind of functionality - one being Measuring watt hours (WH). I would set the voltage to 12.6V (3S) and charge to full - remove the charger - zero the watt/hour meter - heat the VC to the click [exactly] - and charge again. This time I get MWH reading on the power supply meter. Amazing what that data will tell you. Anyway, that is why I know the numbers above are real. Everything is about watts. Another diagnostic tool is the OPUS BC3100 analytical charger. These will read your true battery capacity. Bottom line - everything is about watts which is controlled by voltage.

How to shift the voltage influence you ask? Each turn of the coil represents a virtual 1V baseline. 10 turns per coil; and it happens to like 10V-10.5V remembering that your voltage range is 9-12.6V this is a happy medium. For a 2S setup, the theory is to remove 3 turns from the coil - 7 turn. To get to 70 watts with say nominal 7V on a hot cap. I haven't done it but the numbers bear out. Just know that those cells will be pushing upwards of 10+ amps in 2S to get to 70 watts. The test is 6V performance and 8.4V performance where 6V may be a peeked 45W or 8.4V performance (actually a bit less as battery 'sag' will be present) is too hot at 80-something watts.

Note that I am outing the coil as the variable. It is not to be chosen wildly. The stock coil wire is about 33" long for 12V operation. For 8V operation, that coil wire can be 22" long. The unit will work hard by making up for voltage with current. Current is what makes things hot. As long as you are aware of this, I see no reason not to use the coil wire length as a gauge as to where you want to be on aggressiveness of the end product. Again, an Ammeter or a power supply with a watts meter built in [Shweet!!!] makes quick work of dialing in what you want out of the IH. You can really get a lot of trial runs to know what you want if you have one of those little lab supplies. Then you will be matching up what you know with the portable power source you choose.

 

[ElBarto]

First Let me Apologize if I sound like a noob but I have a bunch of questions regarding the coil switch, batteries, USB, and the half pint.


1. I saw the picture of the magnet wire wired at the bottom and my question is can I use another cable to accomplish the same since I want to avoid buying extra cables if I can accomplish the build with 1 it would be way better. Can I use only 18 gauge or maybe 16 gauge?
Also how does that switch even work, Saw you isolated the pad right where the big blue connector was on and then wired each to negative and positive. is that just to complete the circuit or what? just curious

2. The batteries I'm planning to run are 3 x 18350 which I guess is standard portable IH batteries but I cant really find a holder, I saw being used in the half Pint individual holders for the batteries and wanted to know were you got them and what size batteries you have. I saw then they were just wired together later, assuming I can use 16 gauge wire I would wire it myself and I guess you need a controller for the battery not sure how it is called. After that do I wire the cables from the controller directly on the positive and negative terminals of the charger or do I plug them in to the master on/off switch I'm going to put.

3. I say above in the thread that somebody tried putting USB c but I was wondering in what way to do it properly that I connect any usb c like from my phone or my laptop that it should work always. Am I asking for much or is it possible? Doesn't have to be USB-c, maybe micro USB idk.

4. Regarding the half pint, I am attempting it and I want that as my desk setup and of course as small as possible while still being portable. If anybody has any tips I would appreciate.

5. I wanted to add 1 or 2 LED to make sure the device is on and to know when its in heating mode, I want that especially with the coil switch. What resistor should I get for thee LED 560 ohms or 470 ohms. Idk

The key for me is having the coil switch to reduce space having to put a momentary button for dynavap action. THANKS for taking the time in reading.

Let me know if I am correct or not, just making sure it works lol. Any Info / tip will help

 

[TommyDee]

It's a long subject and it will take me a bit to get through it... and it won't be tonight. Let me know what to expand on first, next ...

1) 18 awg is fine throughout. That matches the wire gauge of the inductor wires. Magnet wire is convenient being rigid. When you dress it, it remains in place.

2) 3D printed holders for 18350s. Thingiverse. Use 18650 clips. https://www.thingiverse.com/thing:4536047

3) 3S wants 12.6V exactly. I opt to charge with quality chargers at 12.6V into the BMS. Any USB-C converter that can output 12.6V reliably can work. Sorry, no links to that.

4) The switch I was showing is a Fluxer style Cap As Switch. They are spring contacts soldered to liberated pads where the 3 pin connector sits. This was to minimize depth to about 2 for a truly heat tolerant switch.

Electrically, this is what the cut did - it can be wired to a switch by any means. The switch is jumped across the cut trace.

 

[ElBarto]

1. Well I assume that with the connections you did, and splicing at the top and bottom (where the parallel wires meet) you have a complete circuit and you get induction once the dynavap is in. Do you have to touch the dynavap on the board to make contact?

3. So this below is the 3S BMS?

I am struggling to find the 12.6 usb c you are talking about. I only see 5 volts everywhere. Are you referring like a usb c wall plug or what. I am lost in that part. I'll just go to regular dc and deliver 12.6 directly to the BMS make it easier.

 

[TommyDee]

The DV cap completes the circuit, yes.
That is a 3S BMS yes - 10 amp, as that one is, is recommended.

You would need a DC-DC converter style USB-C module. I just gave up on coming up looking for a reliable unit. They generate heat and take up space. I have 12.6V chargers galore.