MOSFET Wiring diagram for 2-button, dual voltage?

[BuzzKill]

LOL , never heard that one before Scott NICE !
You should check out the National Semi Sim/circuit designer it is very cool ! , does real circuit sims with power eff. etc. nice stuff.

 

[noo]

(P.S. But a transistor with an RDSon of .5Ω is going to have way too high of a V-drop for our use. At 2A you'd be dropping a full volt at the transistor.)

Of course! That was a typo, the correct value is ~0.05ohms

In the same family there is also an IRF1503 MOSFET with a 0.003ohm saturation resistance that will dissipate up to 330w, in a smaller package. I really want to get my hands on a few because I think I could do some cool stuff with them. So far I have not gotten around to ordering any exotic silicone, and have just been playing with what I have around/the pitiful selection at radio shack.

Anyway, apologies for the off topic conversation, I am trying to get enough posts so I can start my own threads

 

[Global_Apathy]

I'm sure the jumpstart has some sort of kHz boost regulator in it that if you adjust the passives correctly might be able to push out a couple more mA. But that would tracing the ckt and determining the components. I think I read that it does push the "full 400mA" which isn't really enough. Using it cuts a lot of work time though.

I've been researching some buck boost regulators for a mod idea I'm working on. I think if we can regulate the voltage and current out it will lead to more consistent operation.

I might be a little on the cautious side but I don't think that all mechanical pvs are safe... at all... but what do I know I only worked in a battery lab.

 

[candre23]

Others have reported success using the 5v from the USB connector to power an atty, so I figured I'd give it a try. So far, it's not working too well, but I haven't had a chance to track down the problem. The 3.7v circuit is working fine, though.

As for buck/boost regulators, I've been thinking about them a bit myself. My thought experiment of the day was "how complicated can you make a mod?". I decided that realistically, the the limit was a digital variable voltage mod with built-in voltage display. You could use a LTC3785 to get 2-10v from any battery configuration and an X9317 to control it digitally. Then you get an ICL7107 voltmeter-on-a-chip and a small 7-segment LCD to display the voltage.

It's not completely out of the realm of possibility, but you would need to commission a professionally fabbed PCB. I'm pretty sure you can't etch your own boards with the precision necessary for SMT components. Definitely out of my price range. Besides, as mod of this caliber would need a really awesome housing (I'm thinking an FX Lightsaber), and that's just out of my league.

 

[Global_Apathy]

What about smd proto boards as long as everything is the same pin pitch they should work. I have a sorce for those I'll post it when I'm not on my phone

 

[candre23]

That would be fine for a desktop-sized prototype, but to cram that stuff into a mod you would need a custom-made PCB.

 

[Global_Apathy]

http://www.robotshop.com/schmartboa...ource=google&utm_medium=base&utm_campaign=jos

This is just an example of one that could be cut to size

 

[SurvivorMcGyver]

Others have reported success using the 5v from the USB connector to power an atty, so I figured I'd give it a try. So far, it's not working too well, but I haven't had a chance to track down the problem. The 3.7v circuit is working fine, though.

As for buck/boost regulators, I've been thinking about them a bit myself. My thought experiment of the day was "how complicated can you make a mod?". I decided that realistically, the the limit was a digital variable voltage mod with built-in voltage display. You could use a LTC3785 to get 2-10v from any battery configuration and an X9317 to control it digitally. Then you get an ICL7107 voltmeter-on-a-chip and a small 7-segment LCD to display the voltage.

It's not completely out of the realm of possibility, but you would need to commission a professionally fabbed PCB. I'm pretty sure you can't etch your own boards with the precision necessary for SMT components. Definitely out of my price range. Besides, as mod of this caliber would need a really awesome housing (I'm thinking an FX Lightsaber), and that's just out of my league.

I'll comment on this as it has, all along, been MY thought process of "The (eeeer ummmm - MY) Ultimate Mod". Throw one (or two) of TI's bqTINY series Dual Input LI-ION chargers with Power Path Managment in there and you have it in one sweet package. Should be able to fit it into together in a pretty tight package with a multi layer PCB if one could manage the logic and power seperation spaces and traces.

Anyone what to join in on the developement -- call it " The Ultimate Modders COOP (effort)" or whatever--

Mcgyver

 

[SurvivorMcGyver]

PS Not including the Jacks, display, safety switch, atty and all the OTHER
accoutrements that are essential or at least "nice to have"

 

[SurvivorMcGyver]

http://www.robotshop.com/schmartboa...ource=google&utm_medium=base&utm_campaign=jos

This is just an example of one that could be cut to size

You might also try Proto Advantage -. (If your not concerned with size) -- They'll even install your components for you.

Custom made is they way to go though. They are great for a quick way to set up a prototype though Just tell 'em the digikey numbers ya need and ............

 

[noo]

As for buck/boost regulators, I've been thinking about them a bit myself. My thought experiment of the day was "how complicated can you make a mod?". I decided that realistically, the the limit was a digital variable voltage mod with built-in voltage display...

At that point you might as well just use a PIC. You can use it for the PWM control on your regulator, as well as use the ADC to do the voltage detection. And of course, the exercise "Use a PIC to drive an 8 segment/LCD display" is the oldest assignment in micro-computing

 

[candre23]

I've never done any PIC programming. This might be an excuse to give it a try. Any particular model you'd recommend? Something with a cheap dev board?

 

[Global_Apathy]

I have all the equipment here for atmega128... ARM 7... or pic with the ICE (in circuit emulator)... as well as the schtuff from my bs degree... ummm 68hc11 and an altera fpga... now on to the most important commodity... time...

 

[candre23]

Damn. Now I'm seriously considering getting an Arduino mini board to play with. It's small enough to fit in a 2x18350 mod and work without additional power regulation. Now I'm thinking closed loop feedback control, so you set a voltage setpoint and the board maintains it regardless of the battery voltage. It's been a long time since I've done any legitimate EE work, and this is pretty far outside my experience even back then. I doubt this will end well, but what the heck.

 

[5cardstud]

According to Scottbee, diodes aren't necessary as the FETs will not allow backfeed.

Well scottbee knows 10 million times more about cicuitry than i'll ever know. I put that post before I read the others. sorry.

 

[Global_Apathy]

Arduino mini boards are so tiny... but coding them is not quite the same as the regular atmel chips

 

[noo]

The new PIC32's have built in USB programming support; I have not played with one, but I hear they are a breeze to learn. Back when I was doing PIC programming it was all assembly, but I think they have C compilers for them now, so the learning curve shouldn't be too bad.

Cannot comment on the Arduino mini boards but from what I have heard they are a great introduction to embedded programming - it would be great to start an open source e-cig project revolving around one.

@Global_apathy - those altera FPGA's are a little pricey for e cig use eh? I actually have a xilinx prototyping platform from university that I have been wanting to turn into a full on e cig dream mod

 

[noo]

Now I'm thinking closed loop feedback control, so you set a voltage setpoint and the board maintains it regardless of the battery voltage. It's been a long time since I've done any legitimate EE work, and this is pretty far outside my experience even back then. I doubt this will end well, but what the heck.

If it maintains a voltage which is below the battery voltage, the current will drop as it switches to boost mode. Your power dissipation will drop all the same - the best power control scheme IMO is a standard switching regulator if you have room for the reactive elements (ie, the inductor).

 

[candre23]

The new PIC32's have built in USB programming support

Yes, but those boards are huge compared to the Arduino, and it really is way more processing power than is needed for this sort of thing. The Arduino can be easily programmed with a serial-to-USB board which you can then remove so it's not taking up room in the mod.

If it maintains a voltage which is below the battery voltage, the current will drop as it switches to boost mode. Your power dissipation will drop all the same - the best power control scheme IMO is a standard switching regulator if you have room for the reactive elements (ie, the inductor).

Weren't you the one who suggested a PIC with PWM to do variable voltage control in the first place? From my limited understanding, you have the PIC output a square wave and use that to switch a FET. You then use a cap (or maybe a full bridge?) to smooth out the output. Varying the "on" percentage of the square wave should vary the average voltage, no?

 

[noo]

Oh yeah, of course, I thing the PWM design is a fundamentally sound one - just pointing out that that even if you do build a boost regulator, the power dissipation would still drop as the battery died. Still, go to town - it sounds like you have aquite a project lined up.

I would do so much more tinkering if I had the time