voltage display dimming

[randomness]

I noticed that when I adjust the trim on my vv regulator board kit from madvapes, it also dims my voltage display (also from madvapes). Setup is basically 1 18650 bat -> 100uf cap -> ptn04050c booster (to 5vdc) -> 100uf cap -> regulator board -> v. display, using the + / - from the reg board. I guess it doesn't really matter, as it starts dimming around 3.35vdc and I'm not going to use a lower voltage than that but if it's possible I'd like it to retain the same brightness regardless of power from the board. Not sure if a common ground would change this. Any suggestions?

-J

 

[slimest]

This voltmeter should dim. Nothing to correct this without a serious soldering inside the module.

 

[asdaq]

Am I right in understanding that you are using a 04050 to get up to 5v and then the NCP 630A to regulate down from there? What is your end voltage range and what is your sweet spot in this?

 

[randomness]

I'm about ready to throw either a 22kΩ or a 18.5kΩ resistor on the booster to bring it up to 6.2 or 6.4vdc. My sweet spot is normally between 3.8 and 4.9 depending on the atty I'm running. The reason for the extra voltage is to allow for things like indicator leds and the like - plus, who knows, maybe I'll need that extra voltage someday. Oh and I'm capable of getting the display to light from about 2.05vdc on up to 5vdc. I've noticed a voltage drop of about 0.19vdc when firing an atty so I can't really say I'm actually getting 5vdc to the business end.

 

[asdaq]

But are you boosting and then regulating?

sent from my HTC genisis using Tapatalk

 

[randomness]

yes, boosting first then regulating. however I've been mounting each function on individual breadboards so it's just a matter of changing the order.

From original post "Setup is basically 1 18650 bat -> 100uf cap -> ptn04050c booster (to 5vdc) -> 100uf cap -> regulator board -> v. display, using the + / - from the reg board." That's the order of components.

 

[CraigHB]

That's highly inefficient to use two regulators in series like that. The losses multiply. Why don't you just use an adjustable booster for the atomizer output, then use a small linear regulator to power things like LEDs.

 

[randomness]

Soldered in a 22k Ω resistor, now I'm reading 6.2 directly off the booster. once regulator board is added into the chain and the vdisp is attached it reads 5.6 - still an acceptable voltage for me. Tried different ways of attaching vdisp to circuit but it looks like I'm going to live with the dimming. It reads down to about 2.35vdc then shuts off. Still bright at 3.2, is there any way to make the unit as a whole it shut itself off at around 3vdc?

J

 

[randomness]

The adjustable boosters are just some free engineering samples I thought I'd play around with so I'm trying to work within their function and the other misc parts I have laying around. I'm not an electrical engineer by any means, this has just become an exercise to learn more for me.

 

[CraigHB]

Yes, you can incoporate a shutdown circuit. Easiest way is with a MOSFET and voltage detector. Some regulators have an enable pin you can tie to a voltage detector which saves the need to add a MOSFET.

ON Semiconductor NCP300: Voltage Detector Series with Complementary Output

 

[asdaq]

That's what I thought I read, just clarifying. The least efficient is that regulator, all the excess voltage gets burned off as heat. Adding that resistor to the 04050 just made sure it would burn off more voltage. You could do all this with just the booster, adding a resistor and a pot to make it variable and in your case adding a diode in front of the atty would get you a range as low as 4.2v. A 3A barrel diode will take around .7v off as waste heat but it is still better than that linear regulator.

You could even include a slide switch to bypass the booster and use the battery as a 3.7 device and use it from 4.2v and down.
Pretty reasonable with an 18650.
For a schematic for a VV boosted, this guy did one he called the Varbox View Profile: misterD - E-Cigarette Forum

PS: the 04050 has shutdown onboard, about 2.9v.

Largely based on Nuck's Fistpack