"Slow Roast" IH for DynaVap ?

[Mono Loco]

Hi, all.
Man, why am I finding the concept of Induction Heaters and DynaVaps sooooo intriguing? It's like some sort of Black Magic that is bewitching me. I haven't even received my 2018 M yet and I am obsessed with IHs! I have already pestered Pipes directly so I don't wanna' pester him alone - I put this query out there for all of you to share the burden.

If I like my DynaVap as much as I expect to, I do intend to purchase both a basic desktop and a portable IH at some point. For now, though, I am thinking about building my own "bare bones - secured to a small piece of plywood (no enclosure)" unit ... just something to try to see how I like the concept and to use until I make up my mind on the "real" units I want! I have a few questions regarding DIY IH.

1) I guess I will use the "standard" 5~12v ZVS Induction Heating Power Supply Module that everyone seems to use. I am more of a flavor-chaser than a cloud-seeker and I am very interested in the concept of a longer heat time to basically "slow roast" the herb, as promoted by Mr_CfromCali (FluxerHeaters). As I am not interested in battery power, and not interested in fancy PWM, nor faster (more convenient) heat times, can I not simply use something like an 8v power supply (AC/DC transformer brick, wall-wort, etc.) instead of a 12v one? I understand (well, not really, but I was informed) that these IHs put an intense instant demand on the power supply when they kick on so a power supply with a high Amperage rating is required ... accordingly, I know I would need a quality unit (not a 2" cube that plugs directly into the wall). So, if I were to use a high quality power supply with an output of less than 12v (or adjustable/variable to < 12v), would the heat-up be slower than running it at 12v ... AND, would it still get hot enough to Click the Cap?

2) If a <12v PSU is not the answer, what about using a finer gauge copper coil, like I saw in the SKJ "dental wax heater" pics? Maybe a combination of the two. Or, am I asking for trouble if I start changing the variables ... fire hazard?

3) I dislike the feature of a pressure-activated switch residing in the bottom of the IH's coil. I want to put a momentary switch in-line. Like the power supply requirements, I have been informed that a switch with a high Amp rating is required. What brands of switches are known to be durable and high quality?

4) From these threads, I know to "check the polarity of the diodes VD1 & VD2 , and also the polarity of the two Zener diodes DZ1 & DZ2" as the QC on these things is not consistent. (I'm gonna have to review that thread a few times!) Anything other potential issues to look for, or ... common mistakes to avoid? I can do basic soldering - have a WES51 and teeny tips!

OK, that's all for now. I appreciate any help, but please don't go much beyond layman's terms in your answers ... I have very limited understanding of these things! My goal is to build an economical, basic desktop IH that's safe and doesn't heat so quickly.

Thanks!

 

[analytika]

Hi, all.
Man, why am I finding the concept of Induction Heaters and DynaVaps sooooo intriguing? It's like some sort of Black Magic that is bewitching me. I haven't even received my 2018 M yet and I am obsessed with IHs! I have already pestered Pipes directly so I don't wanna' pester him alone - I put this query out there for all of you to share the burden.

If I like my DynaVap as much as I expect to, I do intend to purchase both a basic desktop and a portable IH at some point. For now, though, I am thinking about building my own "bare bones - secured to a small piece of plywood (no enclosure)" unit ... just something to try to see how I like the concept and to use until I make up my mind on the "real" units I want! I have a few questions regarding DIY IH.

1) I guess I will use the "standard" 5~12v ZVS Induction Heating Power Supply Module that everyone seems to use. I am more of a flavor-chaser than a cloud-seeker and I am very interested in the concept of a longer heat time to basically "slow roast" the herb, as promoted by Mr_CfromCali (FluxerHeaters). As I am not interested in battery power, and not interested in fancy PWM, nor faster (more convenient) heat times, can I not simply use something like an 8v power supply (AC/DC transformer brick, wall-wort, etc.) instead of a 12v one? I understand (well, not really, but I was informed) that these IHs put an intense instant demand on the power supply when they kick on so a power supply with a high Amperage rating is required ... accordingly, I know I would need a quality unit (not a 2" cube that plugs directly into the wall). So, if I were to use a high quality power supply with an output of less than 12v (or adjustable/variable to < 12v), would the heat-up be slower than running it at 12v ... AND, would it still get hot enough to Click the Cap?

2) If a <12v PSU is not the answer, what about using a finer gauge copper coil, like I saw in the SKJ "dental wax heater" pics? Maybe a combination of the two. Or, am I asking for trouble if I start changing the variables ... fire hazard?

3) I dislike the feature of a pressure-activated switch residing in the bottom of the IH's coil. I want to put a momentary switch in-line. Like the power supply requirements, I have been informed that a switch with a high Amp rating is required. What brands of switches are known to be durable and high quality?

4) From these threads, I know to "check the polarity of the diodes VD1 & VD2 , and also the polarity of the two Zener diodes DZ1 & DZ2" as the QC on these things is not consistent. (I'm gonna have to review that thread a few times!) Anything other potential issues to look for, or ... common mistakes to avoid? I can do basic soldering - have a WES51 and teeny tips!

OK, that's all for now. I appreciate any help, but please don't go much beyond layman's terms in your answers ... I have very limited understanding of these things! My goal is to build an economical, basic desktop IH that's safe and doesn't heat so quickly.

Thanks!

I'm with you there. In my DIY, no pressure switch. I used a mosfet so I could use a very low power rated switch inline, and have the pick of the litter from the much larger variety of switches available. Sometimes I activate and deactivate the switch, to achieve the slower roasts concept you speak about. But you know what? Much simpler than doing that -- or heaven help us, tweaking the actual power supply or electronics -- i just move the dynavap in and out of the coil about a half to full second at a time while leaving the induction heater on. It doesn't warm up the coil that much in the time it takes to reach the click even when prolonged by this method. I do turn it off after the click until I decide to heat it again.

 

[Denis69]

Hey I am building an IH for my M as well, so I think I can give you few leads

About lowering the voltage, the main concern are the 2 (or 4) transistors controlling the waveform output of your zvs, they a have a commutating voltage command threshold, if that voltage is not reached, commutation wont occur and there are good chances all of the transistors will get blown
Only way to know this threshold for sure : test it, its rated at 5v, some models might actually work with a 5v input

If your button is operating a mosfet, there is no point of worrying about the current its commutating, but rather about bounces it produces (search debounce circuit, I saw it on this board somewhere)

Good luck with your build and enjoy your M

 

[vandalizedbythelotus]

how about uncoiling the coil a bit? i'm thinking unwinding 2-4 turns should lower the power output and req

would this work towards a longer, less power hungry heating cycle?

as i understand it lowering the power input in order to give a longer heat cycle works but actually increases the strain on the PSU. i would rather modify the IH somehow to require less power but i'm quite illiterate myself and just built mine blindly following instructions posted on these forums

edit: also i find the SS tip to have a longer heating time compared to the TI. i find it better suited for lower temps because there's more time to react after the click ...

however i'm noob to those devices i just got a fortnight ago and am currently heavily testing huehuehue

 

[vandalizedbythelotus]

Hi all,

OK, here's the long-overdue update I promised. Sorry for the wall of text, but I guess that's just how I roll, lol.

Flux Deluxe:

Field testing continues and is hopefully close to concluding (!) - I want to wrap it up this week, if possible. To date, my field testers and early adopters have found some excellent issues, as I had hoped they would. Thank you, field testers and early adopters!

The heaters are definitely better now after being tested - they run cooler, and they are less likely to spill completely out of their cases if dropped.

The heaters will leave the testing phase with at least one other nice change to the circuit, an unexpected bonus feature: a temperature adjuster, to allow you to slow the temperature rise a bit! This is meant to be something you set and forget, so for now, there's no ability to adjust the temp on-the-fly. Maybe for V2. .

Why introduce a new feature to a critical part of the circuit at this late stage of the development game? Because this new feature is a really just a simple extension of the new switch debounce circuit, and all it takes to add this feature is ONE additional resistor. It's just too useful not to include it, and it wouldn't stay hidden for very long, anyway, so I might as well introduce it and explain it.

A few weeks ago I introduced the new switch debouncing circuit, which passes the signal from the tactile switch to the PWM relay through a resistor, buffered by a capacitor. This creates a ~60 microsecond (60ms) buffer between the tactile switch and the heater's input relay. This cleans the input signal and what emerges is a single event instead of a series of many quick, disparate events (aka, a bouncing switch). That's the circuit as I first deployed it.

It recently occurred to me that If I added a second, variable resistor in series with the first, I could further reduce the power to the PWM relay.

A quick aside about this PWM relay, and a callback to my first post, at the beginning of this entire thread: While this relay can act as a simple on/off switch, it actually brings a lot more functionality than that to the table, and can do more interesting things if you ask it to. For example, if you give the trigger less power, the relay will, in turn, reduce the power it puts out. Lower power = lower temp = slightly longer heating time.

I have a history with this relay. It played a key role in my first IH project, using a pulse width modulated (PWM) signal signal as an IH temp control. This temp control uses a very different methodology, but it produces similar results.

A few notes about this feature:

1. You don't have to touch this control at all if you don't want to. It will be set to zero by default, making it transparent and imparting no affect.

2. This is an offset, meaning that the circuit has a fixed amount of resistance in place. You will never get any less resistance than that amount, as that base amount of resistance is necessary for the debounce circuit to function properly. This control will never enable the heater to heat more quickly than its default setting.

What you can do with it is add additional resistance to the input trigger signal. This reduces the strength of the heater's output by limiting its input voltage, giving you a crude by nonetheless effective temp control. Some testers reported that the Deluxe heated TOO efficiently, and the time between insertion and clicking could be very short once everything got up to temp, so this is a way to compensate for that and makle it a bit less efficient, if so desired. (Aside: induction heating is much, much more effective when the work coil and the piece being worked are already hot!)

A couple of caveats about this:

1. You need to use this feature responsibly! I debated what range of adjustment I wanted to give the user, and decided to treat you as adults and give you the whole useful range. That said, you want to monitor the time it takes from insertion to click. The ideal time is likely between 4-9 seconds, with ~7 seconds being a nice compromise between flavor, vapor production, battery life, and guarding against heat generation.

2. I have no way to enforce this, but 10 seconds per heating event is a safe maximum event length. Be aware that using it for too long, even at a lower temp, causes the heater to get hot (duh), but this leads to heat soak (i.e., hot parts staying hot) and makes it more likely to trip the thermal fuse. Extended use also works the PWM relay hard, which generates some additional heat around the PWM relay, a spot that does not have a dedicated vent hole. So as I said, please use this feature responsibly.

3. A lower temp can make for a nicer vaping experience, especially if you want to leave your vapcap in the heater for an extra second or two, as one sometimes needs to do with an IH; the lower temp/slower heating time makes it harder to combust, giving you more control over extended heating sessions.

4. The control is can be adjusted with a small flat blade screw driver (no screwdriver included, sorry). There will be a small access hole under the right-most battery's negative terminal, as shown in the photo below. You can also adjust it by removing the battery tray and moving it with your finger.

-=-=-=-=-=-=-=-=-=-=-=-

What happens next:

We are in a holding pattern for a few more days while I wait for some additional testing feedback, just to make sure all is good.

I expect to make a go/no go call by the end of the week.

Sooner, if the testing reports indicate that it's ready.

I am already starting to build out subassemblies while we are waiting, as I think the design is stable. If I need to make a small fix or some such thing after these are built, so be it.

I have 15 battery sleds built out, for example, and another 10 in process. These actually take more time to build than the circuit boards, so this is nice head start.

I have also been honing my enclosure game! I now have some very good methods for installing the magnets w/quick drying epoxy. This used to be a little terrifying (epoxy gives you SO many easy ways to fuck up!), but I have a better command of the process now and it's not only going well, it's actually pretty fun. Same goes for marking and drilling the enclosures. I made some drilling template stickers that make it MUCH easier to precisely mark, punch, and drill the cases. Tip: Use see-through address labels as templates! They WORK, and they come off easily afterwards! You can see these on some of these drilled enclosures:

Drilled enclosures, prior to cleanup. The holes are actually clean; most of the cruft you see are the remnants of the new drilling templates stickers.

Once I'm satisfied that these are good, I'm going to start working through the waiting list, so that you can finally get your Deluxes! With that in mind, I am putting together a big enclosure order, as I want to make sure I have the right colors on hand for everyone who has expressed a preference. If you want a Deluxe but have not yet told me your color, please let me know ASAP, as I will be ordering these enclosures this week. Black is going to be well represented, and I'll have some extra, as well as a few extra natural and dark green cases (and gun metal, if/when that comes in), but if you want something else - blue, green orange, etc, - please let me know ASAP!

And with that, I think I had better bring this novel to a close.

Thanks for your support, everyone! I'm hoping for a successful week!

-=-=-=-=-=-=-=-=-=-=-=-

TL;DR: Fluxer Deluxe testing is going well and should wrap up this week. Some bugs were found and fixed. One new feature was added. Cases take time to drill.

And finally, some pics of the most recent Deluxe:

Thanks all!

 

[mr_cfromcali]

Hi All,

A few things from my own experiences/experiments: lower voltage can mean much longer heating times, and voltages below 9v can take 30 seconds or more from insertion to click, especially when the DV is cold. When I was first looking into making a portable IH I found some ZVS IH heaters on Aliexpress.com that ran on 3.7V ( https://www.aliexpress.com/item/Ind...gh-frequency-heating-machine/32812551075.html ). I actually bought five of these to play around with, thinking I might be able to make something commercially viable with them, but that didn't come to be. (And if anyone wants one, PM me. I'll sell them for, like $5 ea + postage). Anyway, low voltage alone doesn't quite get it done in a way that's satisfying as a user, even if you want to slow roast.

I tried a building a 8.4V (2x 18650) portable IH, and it worked, but it didn't work well. It took too long to heat, and and the overall experience wasn't satisfying. Also, these little heaters work best when their components aren't subjected to long heating cycles. That's been my experience, anyway.

I appreciate any help, but please don't go much beyond layman's terms in your answers ... I have very limited understanding of these things! My goal is to build an economical, basic desktop IH that's safe and doesn't heat so quickly.

Knowledge is power. I think you will need to push yourself a bit to make this happen. I found this to be an excellent resource as I was getting up to speed on zero voltage switching (ZVS) IHs: http://www.kiblerelectronics.com/bob/app_notes/note11/note11.html

It explains the purpose of every component in the ZVS heater circuit, which really helps once you start poking at things.

Finally, as I recently re-discovered (and as @vandalizedbythelotus quoted directly above), the Arduino PWM relay that everyone should be using is a remarkably flexible device. It will respond to a PWM signal, but it will respond to a lot of other things, too. In its typical, straight-up implementation for these IHs, people give it 12 volts as a simple on/off signal, and the relay gives them 12V out. But you can give it a lower voltage input signal, and in return the relay will put out less power. That's what I'm doing in the debounce circuit described/quoted above: I am reducing the input voltage to the PWM trigger, and it responds exactly as you'd want it to.

You might need to acquire some knowledge to pull this off, but from a tech standpoint, this a very doable project.

Good luck!