Want to build my own circuit board for a mod. Need some help!

[benamatic]

I started getting hardcore into vaping the past week. I've been looking for an awesome mod when I came across the Hanna Modz and the Gi2 mod. Found out that they're pretty much always out of stock and you have to get on a waiting list which I think is BS (The Gi2 mod at least). Plus, I don't want to spend $200+ on something that cost half of that. Then I realized that all it is is a circuit board controlling voltage or watts with some safety features. After looking at the Gi2 reviews I found out that the software it runs is pretty simple. I can probably program something like it in about a week. Alot of the features are stupid and useless IMO. So, I decided I wanted something much like the dna 30 but that I could get up to 100 watts out of it. The problem is I'm not an electrical engineer, I am a programmer. I did some more research online and after thinking about it, I figured out the following.

1. I need to measure the resistance. (Ohms) To do that I first need to know the voltage the battery is generating. The starting voltage and wattage will be preset. (The watts need to be preset anyways since it's needs to be displayed.) Then, using the ohm's law algorithm I can calculate that by using,
Amps = Watts / Voltage
Ohms = Voltage / Amps

2. The watts are displayed and are controlled by the user. By changing the watts it then changes the voltage and amps.
Amps = sqrt(Watts / Ohms)
Voltage = Amps * Ohms

The information I found above was taken from http://www.ohmslawcalculator.com/ohms_law_calculator.php and looking at the algorithms he was using from source.

One thing I'll have to decide on is the default starting value for volts, watts (Maybe there is a industry standard). The safety features will probably come along later once I have all of the above worked out and running.

Does this sound about right? Any ideas or suggestions? Please let me know.

I will keep adding to the first two posts as I make progress.

 

[benamatic]

After doing some more research I found that the highest wattage my unit will be able to produce will have to be around 30. It could go up to 50 watts but I don't think I want something that last 20 minutes on 2 batteries. These are some of the components I will be using,

1. The regulator
This unit is in charge of producing that regulated voltage, basically the power supply. It also has safety features such as making sure the unit doesn't over heat, etc.

2. Current shunt monitor IC
This unit is in charge of giving me the voltage output so I can calculate everything and display it.

3. Processor
Used to calculate everything in the above post.

4. OLED/LCD
The display.

There are a couple other components that I have to finalize. Will give an update when I do.

 

[CreepyLady]

Once you have one more post and the servers reset you can have the mods move it over there for you. If you reply to me on this thread you will be good to go. The server resets at 20 or 25 past every hour.

 

[benamatic]

Once you have one more post and the servers reset you can have the mods move it over there for you. If you reply to me on this thread you will be good to go. The server resets at 20 or 25 past every hour.

Cool! Thank you for the info.

 

[Completely Average]

1. I need to calculate the resistance. (Ohms)

You CANNOT calculate the resistance. You have to MEASURE the resistance. Different coils have different resistances, and as you use a coil it's resistance gradually increases.

To do that I first need to know the voltage the battery is generating. Easy enough, Then, using the ohm's law algorithm I can calculate that by using,
Ohms = Voltage / Amps

Uhh, yeah. And how exactly are you going to know the amp draw if you don't know the resistance?

Amp = Wattage / Voltage
Wattage = Voltage * Voltage / Resistance

The voltage would be a known number, but wattage and amperage are variables that you cannot measure or calculate without knowing the resistance first.

2. The watts are displayed and are controlled by the user. By changing the watts it then changes the voltage and amps. By setting it up this way the resistance doesn't change.
Voltage = Amps * Ohms
Amps = Watts / Voltage

If I put a 1.0 ohm coil on it how does your math work? If the resistance doesn't change then how does your math work if I put a 1.5 ohm coil on it?

Resistance is controlled by the user. The resistance will be whatever ohm coil the user attaches to the mod. In a Variable Wattage situation the wattage would be a fixed number set by the user, the coil resistance would be a fixed number determined by measuring the coil, and the voltage would be altered by your PCB.

Does this sound about right? Any ideas or suggestions? Please let me know.

Honestly, I think you're WAY over your head here. You may know programming and if everything was laid out for you by a proper electrical engineer I'm sure you could write the software to do what he tells you needs to be done, but you really need that electrical engineer. And no offense, but I seriously doubt you have the skills necessary to design and assemble a PCB.

 

[benamatic]

You CANNOT calculate the resistance. You have to MEASURE the resistance. Different coils have different resistances, and as you use a coil it's resistance gradually increases.

Thanks for the reply. Sorry for using poor vocab there. I meant measure. I could measure it if I had a preset voltage and amp value.

If I put a 1.0 ohm coil on it how does your math work? If the resistance doesn't change then how does your math work if I put a 1.5 ohm coil on it?

It change every time you put a new atomizer on. In other words, the entire process starts over again once you replace the atomizer.

Resistance is controlled by the user. The resistance will be whatever ohm coil the user attaches to the mod.

True, but once it's attach it doesn't change. Unless you put a new one on.

Honestly, I think you're WAY over your head here. You may know programming and if everything was laid out for you by a proper electrical engineer I'm sure you could write the software to do what he tells you needs to be done, but you really need that electrical engineer. And no offense, but I seriously doubt you have the skills necessary to design and assemble a PCB.

The PCB is the easiest part. There are many many websites out there that make whatever you want. Just have to send them the outline.

 

[retired1]

Moved to Modding. In about 9 minutes, OP can post here.

 

[Completely Average]

Thanks for the reply. Sorry for using poor vocab there. I meant measure. I could measure it if I had a preset voltage and amp value.

But that's my point. You will NOT have a preset amp value without knowing the resistance FIRST.

Amps is the wattage divided by the voltage. How are you going to know the amps without knowing the wattage first?

Wattage is the voltage multiplied by the voltage and then divided by the resistance. How will you know the wattage without knowing the resistance?

If you allow the user to set the watts then the voltage will be a variable, changed based on the resistance.
If you allow the user to set the voltage then the watts will be a variable, changed based on the resistance.

You cannot calculate amp draw until both wattage and voltage are known, fixed numbers.


The first think you're going to need is a built in ohm meter to measure the coil the user installs before the mod is fired. You'll then have to take that ohm reading and the wattage setting to determine the voltage that will be required. Then you can determine the amps that will be drawn.

There is no way you can do this math without knowing the resistance FIRST. You cannot reverse calculate to find the resistance because voltage, wattage, and amps are all variables based on the resistance.

 

[benamatic]

Hmm, having preset everything i guess is not the solution. Then, my question is, anybody know how the ohm meter works? Talking about the algorithm.

Another question, since I don't have a DNA 30 device or a Gi2, can someone please tell me what voltage and amps those devices start with by default, if it does have a default value at all? (Take battery out and put back in) I honestly think this is possible to make.

I'll take apart my ohm meter once it arrives in the mail. Maybe it's not as hard as it seems.

 

[benamatic]

But that's my point. You will NOT have a preset amp value without knowing the resistance FIRST.

Amps is the wattage divided by the voltage. How are you going to know the amps without knowing the wattage first?

Wattage is the voltage multiplied by the voltage and then divided by the resistance. How will you know the wattage without knowing the resistance?

If you allow the user to set the watts then the voltage will be a variable, changed based on the resistance.
If you allow the user to set the voltage then the watts will be a variable, changed based on the resistance.

You cannot calculate amp draw until both wattage and voltage are known, fixed numbers.


The first think you're going to need is a built in ohm meter to measure the coil the user installs before the mod is fired. You'll then have to take that ohm reading and the wattage setting to determine the voltage that will be required. Then you can determine the amps that will be drawn.

There is no way you can do this math without knowing the resistance FIRST. You cannot reverse calculate to find the resistance because voltage, wattage, and amps are all variables based on the resistance.

Thanks for helping me work this out though. Sometimes it's better to talk this kind of stuff out. I'll figure it out eventually.

 

[thetyh]

Ahh, finally I can reply.
First: What are you going to program in the first place? Arduino? Raspberry Pi? A different micro-controller?
Second: You'd need to write the code to measure the ohms then set that as a variable (R)
Since R varies from build to build, you need to make sure the device checks ever so often (right when the firing button is pressed?) to either keep or change the values V and I.
Assuming you want a variable wattage device (like the DNA), you would have to write the code for a digital potintiometer to go up or down in incriments of .1 watts, and display (i'm assuming) that shows the users preferences.

Third: Once the user has set their preferred wattage, you would take your known variables, R and W and use them to find the voltage the device needs to output. The formula for this is V=sqrt(R*W)
Although Amps do matter, they're only needed to make sure the device is safe and doesn't go over the limits of any of the components. It would be best to put a fuse in the circuit that won't allow you to go over a certain amperage, but that's not completely necessary.

I've considered doing the same exact thing, I'm just not very good with programming.

 

[benamatic]

Ahh, finally I can reply.
First: What are you going to program in the first place? Arduino? Raspberry Pi? A different micro-controller?
Second: You'd need to write the code to measure the ohms then set that as a variable (R)
Since R varies from build to build, you need to make sure the device checks ever so often (right when the firing button is pressed?) to either keep or change the values V and I.
Assuming you want a variable wattage device (like the DNA), you would have to write the code for a digital potintiometer to go up or down in incriments of .1 watts, and display (i'm assuming) that shows the users preferences.

Third: Once the user has set their preferred wattage, you would take your known variables, R and W and use them to find the voltage the device needs to output. The formula for this is V=sqrt(R*W)
Although Amps do matter, they're only needed to make sure the device is safe and doesn't go over the limits of any of the components. It would be best to put a fuse in the circuit that won't allow you to go over a certain amperage, but that's not completely necessary.

I've considered doing the same exact thing, I'm just not very good with programming.

Thanks for the reply, I have both an Arduino and a Rasberry Pi. Will probably use one or the other for this prototype, then eventually use a PCB once I figure out all the chips and components I need. Kind of thought about starting a open source project but don't think there would be anybody interested. If I pull this off, probably end up selling mods with them in it for super cheap. printed box, stuff like that. As for checking R probably have to check it constantly. I feel like having to press a button to check is inconvenient and annoying. I'll starts this up on the weekend and see what I can accomplish. Super busy atm.

 

[thetyh]

I actually have the design for a DNA 30 mod that I'll be producing 100 of soon, but if I can help you come up with a solid PCB and code, I'd rather use my own board and work than have to wait for forever on the DNA chips. I have a DNA 30 board that I can check stuff on, like starting and ending voltage, highest wattage, etc.. And the DNA actually does exactly as I described, the fire button is pressed, it measures the resistance, then sets the voltage.

If you get the chance, PM me.

And what's funny is I was about to post just about the exact same thing you posted today, you just beat me to it..

 

[benamatic]

That's actually the reason why I started this. I hate waiting. So basically, I want to make my own but one up them and make it go up to 50 watts or even 100 watts. A lot of testing is needed. I say that because there is definitely a reason why they only go up to 30 watts. I know they can go higher for a fact but their safety measures only allow it to top out at 30. It would be awesome if I can get someone with a Gi2 mod to help out.

 

[DKP#]

I would be very interested in an open source project and have even searched for one myself. I was surprised when I didn't find one.
I've thought about making a mod with the MSP430 uC. Something programmable like the evic. I just ordered a some electronics from fasttech with my vaping stuff to get back into in programming micro-controllers.
I know there's some good power circuit info buried here somewhere, I remember seeing it a year or so ago.

For defaults, I think the usual minimum of 3 Volts or so would be best.

To measure resistance, you could put a known precision resistance in series with the coil, then measure voltages. You wouldn't even need to supply a calibrated voltage to do it. You also wouldn't have to worry about a short (0 ohm coil). I think you could even use a large resistance to keep power down without sacrificing too much accuracy.

Circuit:
Voltage_supply----Point_A----Known_Resistance----Point_B----Unknown_Resistance----Ground

Formula (Voltage divider)
Voltage/Total_Voltage = Resistance/Total_Resistance

Math for circuit:
Point_B_Voltage/Point_A_Voltage = Unknown_Resistance / (Unknown_Resistance+Known_Resistance)

Isolate Unknown_Resistance:
//substitute single letters for clarity
B / A = U / (U+K)
//cross multiply
U*A = B*(U+K)
//expand
U*A = B*U + B*K
//All U on one side
U*A - B*U = B*K
//factor out U
U*(A - B) = B*K
//isolate U
U = (B*K) / (A - B)
//put long names back in
Unknown_Resistance = (Point_B_Voltage*Known_Resistance) / (Point_A_Voltage - Point_B_Voltage)

 

[benamatic]

I would be very interested in an open source project and have even searched for one myself. I was surprised when I didn't find one.
I've thought about making a mod with the MSP430 uC. Something programmable like the evic. I just ordered a some electronics from fasttech with my vaping stuff to get back into in programming micro-controllers.
I know there's some good power circuit info buried here somewhere, I remember seeing it a year or so ago.

For defaults, I think the usual minimum of 3 Volts or so would be best.

To measure resistance, you could put a known precision resistance in series with the coil, then measure voltages. You wouldn't even need to supply a calibrated voltage to do it. You also wouldn't have to worry about a short (0 ohm coil). I think you could even use a large resistance to keep power down without sacrificing too much accuracy.

Circuit:
Voltage_supply----Point_A----Known_Resistance----Point_B----Unknown_Resistance----Ground

Formula (Voltage divider)
Voltage/Total_Voltage = Resistance/Total_Resistance

Math for circuit:
Point_B_Voltage/Point_A_Voltage = Unknown_Resistance / (Unknown_Resistance+Known_Resistance)

Isolate Unknown_Resistance:
//substitute single letters for clarity
B / A = U / (U+K)
//cross multiply
U*A = B*(U+K)
//expand
U*A = B*U + B*K
//All U on one side
U*A - B*U = B*K
//factor out U
U*(A - B) = B*K
//isolate U
U = (B*K) / (A - B)
//put long names back in
Unknown_Resistance = (Point_B_Voltage*Known_Resistance) / (Point_A_Voltage - Point_B_Voltage)

That's some pretty awesome info! This project will be taking a little longer than I thought. I've bought most of the hardware for my first prototype. Need to test that out and try a different setup I came out with. I guess I should also try your setup also just because I can. I have been considering creating a open source project but want to have at the very least a prove of concept model. I'll keep you posted, and everybody that's interested.

 

[Alexander Mundy]

Just have the regulator output it's lowest voltage for a very short period and measure the amperage. Should be be able to done in microseconds so that the coil doesn't heat up. I ran across a board one time that was just the power electronics for use with an external controlling device (processor) that was intended to simplify design of a system. If I run across it I will post. There are also digital controlled boards with built in processors that do not rely on an external resistance to set voltage but take commands with special protocols. Here are some GE down converters that use PMBus DLynx* | GE Industrial Solutions I don't remember if you mentioned whether you wanted down conversion, up conversion, or both. You will find down converters with the voltage and amperage range you need more plentiful than the other two since industry uses them a lot. If an up or up/down then you will probably either have to design (simple on paper but difficult in the real world even for an EE that doesn't work in the field) the power electronics or find a power block like I ran across once.

 

[benamatic]

Damn, just found out that the SX350 is out. (or at least I think it is) Really no point to build my own anymore. Finally, China is in the game. Almost guaranteed a steady stream of 30W boards. They claim to be able to produce 10k per day. I think I'll still try to build my own, but not as in a hurry as I was.

 

[Alexander Mundy]

Damn, just found out that the SX350 is out. (or at least I think it is) Really no point to build my own anymore. Finally, China is in the game. Almost guaranteed a steady stream of 30W boards. They claim to be able to produce 10k per day. I think I'll still try to build my own, but not as in a hurry as I was.

Did you find a place to get the SX350? The MOQ appears to be 50 from YiHi. I had enquired about one or two to test and never got a reply. It is a buck / boost board which I would like to get my hands on.

 

[mostlyclassics]

Rather than work so hard to reinvent the wheel, why don't you just scare up a Vamo with a broken "fire" button? That's usually why they die — everything else on them is usually fine. Then you'd have all the circuitry, pre-programmed, plus a nice display, all for ultra-cheap. Or buy a brand-new Vamo for $26 or so from Fasttech.