Raptor Flip-Top VV Mod with 20A, 120W dc/dc converter...

[mamu]

There's no difference between digikey and mouser - both are reliable with fast shipping. You can save on shipping cost though at digikey as they offer 1st class and it seems to be just as fast as priority shipping for me. Sometimes one will have stock and the other not. 4.7K is a common value so your local electronics store or Radio Shack should carry it if you want to save on shipping.

I have an assortment of 4.7K ohm resistors that I've bought at various places over these last years. But resistor specs other than the 4.7K ohm is at your option - carbon vs metal, 1% tolerance if you want 4.7K spot on, else 5% is ok. 1/8W or 1/4W - no need for higher power. Leaded (axial or through hole) is preferred over smt, but some prefer working with smt parts.

 

[ftlum]

There's no difference between digikey and mouser - both are reliable with fast shipping. You can save on shipping cost though at digikey as they offer 1st class and it seems to be just as fast as priority shipping for me. Sometimes one will have stock and the other not. 4.7K is a common value so your local electronics store or Radio Shack should carry it if you want to save on shipping.

I have an assortment of 4.7K ohm resistors that I've bought at various places over these last years. But resistor specs other than the 4.7K ohm is at your option - carbon vs metal, 1% tolerance if you want 4.7K spot on, else 5% is ok. 1/8W or 1/4W - no need for higher power. Leaded (axial or through hole) is preferred over smt, but some prefer working with smt parts.

Thanks again!

Frank

 

[mamu]

I updated my wiring guide to include a master kill switch.

We've found that the zener diode does not block idle current drain, so you HAVE to remove the batts from the mod at cutoff voltage, or have a master kill switch, else the batts will continue to drain past an unsafe voltage.

With idle current drain wiping out our batts if left in the mod past the cutoff voltage, it would be a good idea to include a master kill switch, especially those mods with internal lipo batts in which you can't easily remove the batts. A master kill switch also, of course, protects the converter from accidentally firing the atty.

The important consideration for a master kill switch with these converters that have idle current at the on/off control is to have a disconnect between Vin and voltage source. With a DPST switch wired as shown in the guide, Vin is disconnected from voltage source and also on/off control when the switch is in the off position. You can safely leave the batts in your mod for however long you like and not have to worry about current drain - as long as you remember to turn the switch off - that I can't help you with.

(Edit: a rated slide switch is needed).

I also updated the guide to recommend a 4.7K ohm pull-down resistor, instead of the 7.5K.

The wiring guide is updated in the OP, but here it is also...

 

[Tinker Ray]

I like the idea of the kill switch, but I don't understand how it will not have to carry the full current load of the circuit. It could be wired so each section of the switch only carries up to 10 amps - half of the total required. What am I missing?

 

[Portertown]

Fatdaddyvapes has a new style 510 connector they just put on their web site a couple of days ago.

Here is how they describe it:

"510 Connectors for Box Mods
Spring loaded 510 connectors with direct solder point on positive post. Spring is not part of the conduction. Comes with solder collars and hex nuts.
Optional 22mm locking washer for that flush 22mm look."

SHOP - FatDaddyVapes.com - Home of the best vape tweaks and replacement hardware.

 

[Tinker Ray]

I like the idea of the kill switch, but I don't understand how it will not have to carry the full current load of the circuit. It could be wired so each section of the switch only carries up to 10 amps - half of the total required. What am I missing?

Well, I just figured it out...sorry about the comment Mamu, I now realize you are absolutely correct. The contact rating I was worried about is for make/break current. Since the fire switch is in the circuit, the master switch make/break at current never occurs, therefore the rating is relatively unimportant. Very Cool! This does solve a problem I've worried about for some time, and I've learned something new today. Thank You!

 

[BJ43]

Well, I just figured it out...sorry about the comment Mamu, I now realize you are absolutely correct. The contact rating I was worried about is for make/break current. Since the fire switch is in the circuit, the master switch make/break at current never occurs, therefore the rating is relatively unimportant. Very Cool! This does solve a problem I've worried about for some time, and I've learned something new today. Thank You!

I still don't see it....

 

[Tinker Ray]

BJ, you made me dig a little deeper, and at the risk of causing more trouble, I'll offer some thoughts... The make/break is for voltage, as in arcing over when the contacts are moved to open (mostly). The current rating is the continuous hold current, which is really where my concerns originated. The switches I've been looking at usually have a DC rating of 28 volts and something like 3-5 amps continuous current. In the above circuit, unless the fire switch is held on, the master switch doesn't see any voltage or current when operated and becomes a passive connection. One could "fudge" a bit on the ratings - 28V x 5A = 140W. Since the circuit won't see more that 8.4V it should work - 140W/8.4V = 16.67A. This is likely incorrect thinking, but could explain why it works at all. I think the best approach would be to use BOTH sides of the switch wired together in parallel for the master on/off function. As long as the fire switch is connected on the Vin+ side of the M.S. it will work.

 

[BJ43]

Mamu said:
Good news is that, like the fire switch, with the master kill switch tied to on/off control you don't need a rated DPST on/off slide switch. Without having to have a rated slide switch you should find these readily available and in smaller sizes.

I still don't understand this as I see all the Vin (amps) going thru the switch...

I understand there would be no arcing.

 

[Tinker Ray]

well, the worst that could happen is that a failure might keep it from working at all, although if it was your only vape machine...

 

[mamu]

oh wait lol... I think I got what I did wrong. I was only looking at one part of the switch - the Vin-on/off control side.

Right - there is current going across the switch from batt + to Vin.

So, it does need a rated slide switch unless there's a different way to wire this.

 

[BJ43]

Mamu I understand your diagram, what I don't understand is why you say we don't need a high amp slide switch. If i use a .4 ohm coil at 30 watts, that is 8.6 amps. The main reason I wanted the raptor and 20 amps was to try low ohms and these can be very high amp users. I realize that the input amperage with the higher voltage will be less than the output amperage at lower voltage but still many small slide switches are not rated even for 3 amps. Sorry if I am missing something. I want to learn.

 

[BJ43]

oh wait lol... I think I got what I did wrong. I was only looking at one part of the switch - the Vin-on/off control side.

Right - there is current going across the switch from batt + to Vin.

So, it does need a rated slide switch unless there's a different way to wire this.

LOL, I was going crazy.....

 

[BJ43]

Still think that there should be a 20+ amp mosfet that would disconnect the current if the voltage got below a certain voltage controlled by a zener diode. I just do not know how to pick the right mosfet or zener.

We used mosfets with high amps as fire switches activated with small tact switches on some mods a while back.

If I put a mosfet on the input.
I see some mosfets that have a gate v of 5.5v, can I assume that if the gate voltage is less than 5.5 v no current will pass. Then if i control the gate with a 6.2v zener that would prevent any current getting to the gate less than 6.2v, it should not fire.

 

[mamu]

LOL, I was going crazy.....

I had a major duh-oh moment there when it hit me.

Somebody just shoot me already.

 

[Alexander Mundy]

Still think that there should be a 20+ amp mosfet that would disconnect the current if the voltage got below a certain voltage controlled by a zener diode. I just do not know how to pick the right mosfet or zener.

We used mosfets with high amps as fire switches activated with small tact switches on some mods a while back.

If I put a mosfet on the input.
I see some mosfets that have a gate v of 5.5v, can I assume that if the gate voltage is less than 5.5 v no current will pass. Then if i control the gate with a 6.2v zener that would prevent any current getting to the gate less than 6.2v, it should not fire.

I could and have been wrong before, but I don't think the gate would bias the Zener enough. Adding a bias resistor would defeat the purpose. If I can dig up a few parts I will test that when I get back to town if someone else doesn't first.

 

[Tinker Ray]

I may have found an answer to the switch problem - call it an arming switch and find it under R/C electric aircraft. You can buy premade units or buy the connectors to make your own. Check out this one for some ideas: MPI Arming Switch, with Ultra Dean Plugs & AWG14 wires (MPI6970) - troybuiltmodels.com

Just a thought
Ray

 

[BJ43]

My problem would be losing the jumper.

 

[Tinker Ray]

yeah me too...maybe tie a string on it? nothing like a bit of good 'ole quick n' dirty

Actually, it might be possible to emulate the function of a small knife switch, or adapt the concept of a small mechanical fire button configured to Normally On, Locked Off. For my Raptor project, I want small since it will also be a bottom feeder. I am going to test my switch rating ideas from my earlier post when I prototype the board, and will likely try these new ideas as well. I guess I'll have to study the mech mod posts about fire buttons too.

ray

 

[BJ43]

yeah me too...maybe tie a string on it? nothing like a bit of good 'ole quick n' dirty

Actually, it might be possible to emulate the function of a small knife switch, or adapt the concept of a small mechanical fire button configured to Normally On, Locked Off. For my Raptor project, I want small since it will also be a bottom feeder. I am going to test my switch rating ideas from my earlier post when I prototype the board, and will likely try these new ideas as well. I guess I'll have to study the mech mod posts about fire buttons too.

ray

Simplest would be a three pin socket with the jumper to one side on and to the other side off. That way the jumper would always be on the mod. Still I would like it to be automatic and fail safe.