Vamo Pcb for a pass-through

[WolfeTX]

I would really like to know more info on this myself. I use a vamo v2 as my mod and have been wondering if i could make a insert the size of a 18xxx battery with the power wires at the top and bottom like a battery would have and notch the vamo tube for the wire so it would still screw together. So i could use my vamo on a power supply while at my desk and just pop a real battery in while i am on the go.

Barring that i would like some info on what board to use for making my own vv usb wall charger powered mod. It would be sweet also if it had a ohm meter function like the vamo has.
The wall charger i have says its 5v at 2amp.

 

[Innocuous]

I can see no reason at all why you can't make an insert and route out to a PS. I can't recall the amps of a vamo any more - 3 or 4a? I suspect you could simply use a wall-wart and anything from 4 to 12v to your insert.

In fact, sideline the lower tube and cap: just build a "handle" the contacts the pos-pin and provides neg from the input-cable to the outer-tube. Sounds like a bit of wood dowel and epoxy-putty, and maybe some house-wire copper. Maybe even some ducttape or electrical tape.

 

[WolfeTX]

Cool thanks Dont want to like mess my vamo up trying it out. Some oen said that the vamo doesnt operate from between 4.5 and 6.3 volts. My wall charger is at 5volt and 2amp. What would i have to do to get that to work? it was BryanM that said it.
I am confused because my 18650 battery reads 4.2 volts at full charge and the vamo goes low v display at 3.2 volts.
I like the idea of just setting the lower battery tube aside for the usb part. For looks i could maybe find a extra vamo bottom screw on cap and run the wire and mock battery to it. So when at my desk i just unscrew the 18650 tube and cap and screw the usb power cap in.
Would be interesting to also see if there was a market for some thing like this to turn mods into desk powered units. Use your fav mod while at your desk just unscrew your battery endcap and screw in your usb end cap.

 

[Innocuous]

Vamo's operate on one or more cells in series. Whatever their PCB does, there are posts all over about 2x18350 and even 4-5 cells.

Since these are all 3.7v, 4.2...12v sounds fine to me. Yes, 7-9v wallwarts are likely fine, but 2amp is pretty low: 3-5amp supplies would likely work better.

I would simply not ruin the existing tubes and caps - just build something that can be taken apart and replace the Vamo to original shape for a roadtrip, etc.

 

[Mad Scientist]

Cool thanks Dont want to like mess my vamo up trying it out. Some oen said that the vamo doesnt operate from between 4.5 and 6.3 volts. My wall charger is at 5volt and 2amp. What would i have to do to get that to work? it was BryanM that said it.
I am confused because my 18650 battery reads 4.2 volts at full charge and the vamo goes low v display at 3.2 volts.
I like the idea of just setting the lower battery tube aside for the usb part. For looks i could maybe find a extra vamo bottom screw on cap and run the wire and mock battery to it. So when at my desk i just unscrew the 18650 tube and cap and screw the usb power cap in.
Would be interesting to also see if there was a market for some thing like this to turn mods into desk powered units. Use your fav mod while at your desk just unscrew your battery endcap and screw in your usb end cap.

To use the 5V supply, just put a diode forward biased in series with one of the supply legs. It will drop the voltage by .7 and you'll end up with 4.3V. If that's still too high, add a second diode for another .7V drop. You'll end up with 3.6V. Use diodes that can handle at least 2A and keep track of your current draw -- don't exceed the 2A limit of your supply.

 

[WolfeTX]

Thanks Innocuous and Mad Scientist could you put me to which ones i would need? I am a bit of a circuit noob. I can build just about anything but whe nit comes to parts list and such iam just not that knowledgeable. A simple diagram would rock.

 

[Innocuous]

just take off the tube and cap and look at what the battery must contact.

center-post in top-end (a bolt or nail, etc); and the shell itself (a loop of copper? hoseclamp? pressfit wire held by wood handle?)

 

[Mad Scientist]

Thanks Innocuous and Mad Scientist could you put me to which ones i would need? I am a bit of a circuit noob. I can build just about anything but whe nit comes to parts list and such iam just not that knowledgeable. A simple diagram would rock.

This is likely perfect. It's a 10A diode with Vf (forward voltage drop) of 1.04V. Wire it forward biased (one way is just connect the positive lead of your supply to the diode anode and the positive input of the mod to the diode cathode -- the negative lead of the supply goes direct to the negative input of the mod board) and it will drop the supply voltage by just a bit over a volt.

DPG10I400PA IXYS | Mouser

 

[WolfeTX]

Awesome! Thanks so much for taking the time to help and looking that up for me!

 

[Rocketman]

That diode is spec'd for 1.04 volts drop at 10 amps.
Drop at 3 amps would be closer to 0.7 volts.


VF, max, TVJ=150°C 1.04 V
@ IF 10 A

 

[WolfeTX]

What about using a lm2596 step down board? Pretty cheap and could make it so a wide range of sources could be used. I see na few of those used in box mod vids to make the mod vv but in this case it would be to get the volts in range for the vamo.

I did try a little experiment tonight. I had some plastic rod just a little slimmer than a 18xxx battery. I cut it down so it would be just long enough to reach the positive contact Drilled down the center ran the + wire through it and soldered a small flat head screw to it a little hot glue and pulled it back into the rod so it sat flush almost. I then ran the stripped the negative wire and ran it along the out side of the rod. over this i wrapped foil so it was a nice fit into the vamo. while making sure it would make good contact with the inside but not fall out or be to tight to get back out. Put it in and then plugged it into the wall charger. Got the 3 flashes, turned on the vamo and hit the battery voltage checker. Read 5.2 volts.
It would not fire (i didnt expect it to since that falls into the 4.5 to 6.3 no go range). I can get a lm2956 pretty cheap and that would allow me to step down what the vamo needs. Maybe one of you knows of just a fixed regulator that would give say 4v output regardless of how high the input is? I say one vid of a guy using some thing like that but no part number. It was a small black square with like 3 solder points on it.

 

[Mad Scientist]

That diode is spec'd for 1.04 volts drop at 10 amps.
Drop at 3 amps would be closer to 0.7 volts.


VF, max, TVJ=150°C 1.04 V
@ IF 10 A

Nope. Check the Vf vs If curve at 25 degrees C. http://ixdev.ixys.com/DataSheet/DPG10I400PA.pdf

Vf is about a volt at 3A and 25 degrees C junction temp. And yes, coincidentally, also about a volt at 10A and 125 degrees C junction temp. Isn't solid state physics fun lol.