Resistor vs Regulator

[jaymcelhone]

From my research it would seem that a 5v mod using a resistor would need a constant input voltage supply. However when we are dealing with batteries this is not possible. So as the battery voltage is depleted the the voltage through the resistor would also be lowered. The other problem with a resistor would be that to lower voltage though a circuit would require the excess current to be dissipated as heat. In my experience the same is not true with Ldo voltage regulators. In my trials the resistors become too hot to touch while the regulators dissipate some heat but not even close to a resistor. I was using a 1ohm 2w resistor. Also a regulator would supply a constant 5v until the batteries were depleted. My question would be why would any manufacturer use a resistor instead of a regulator? If I am wrong in this thinking please someone correct me. I am not an electrical engineer and would be happy for anny info from a professional in this matter.

 

[Nuck]

From my research it would seem that a 5v mod using a resistor would need a constant input voltage supply. However when we are dealing with batteries this is not possible. So as the battery voltage is depleted the the voltage through the resistor would also be lowered. The other problem with a resistor would be that to lower voltage though a circuit would require the excess current to be dissipated as heat. In my experience the same is not true with Ldo voltage regulators. In my trials the resistors become too hot to touch while the regulators dissipate some heat but not even close to a resistor. I was using a 1ohm 2w resistor. Also a regulator would supply a constant 5v until the batteries were depleted. My question would be why would any manufacturer use a resistor instead of a regulator? If I am wrong in this thinking please someone correct me. I am not an electrical engineer and would be happy for anny info from a professional in this matter.

Simple answer is cost. Resistors are pennies while a good regulator even in quantity is going run ya 6-7 bucks.

You're right about resistors in that the output is relative to the current voltage supplied. The regulators are a better solution.

 

[jaymcelhone]

If your going to supply a product that people are going to use and tell there friends about how great it is and charge a premium price for. The $6 regulator should not be overlooked. Considering the other parts needed to make a mod are very inexpensive. The majority of the cost of a custom mod is in time and labor of manufacturing.

 

[Fairlane64]

You can get small regulators pretty cheap really, like here at madvapes: madvapes.com/Details.aspx?itemId=MV5VREG

The circuit really just entails a couple of resistors to set the voltage out regulation, or if you think you're pushing the regulator too far, it can be used in a really simple circuit to bias a higher current output transistor to supply the power for the atty.

In other words, for less than 10 bucks in parts (not including shipping), you can make a usable 5V regulated output circuit for driving an atty. I'm getting ready to make one in the next few weeks with a regulator that uses two 3.7v batteries (in series) as the supply voltage for the circuit. Stuff it all in a 3XAA box, and you have a Nicostick on steroids!

 

[jaymcelhone]

madvapes.com/Details.aspx?itemId=MV5VREG

This is a 1.5A regulator, I am not convinced it will give the results most would expect from a 5v mod.

 

[Fairlane64]

The best I can tell using ohms law is that you should see right around 1.5A draw from a typical 510 atty at 5V, and 14500 3.7v batteries have a maximum discharge rate of approx. 1.5A (depending on the mah rating), so I'm willing to bet I won't need the higher power output pass transistor to do the job. If my calculations are wrong, it's only a couple more very cheap parts to supply additional current.

 

[Nuck]

The best I can tell using ohms law is that you should see right around 1.5A draw from a typical 510 atty at 5V, and 14500 3.7v batteries have a maximum discharge rate of approx. 1.5A (depending on the mah rating), so I'm willing to bet I won't need the higher power output pass transistor to do the job. If my calculations are wrong, it's only a couple more very cheap parts to supply additional current.

A 510 draws about 2.2 amps at 5v. Those regulators won't work well for ecigs. The TI ones are superior in both max current and drop out voltage.

The OP's question still stands and he's right. There is no good reason that the 5v mods that are being sold are so primitive in terms of power management.

 

[Fairlane64]

A 510 draws about 2.2 amps at 5v. Those regulators won't work well for ecigs. The TI ones are superior in both max current and drop out voltage.

The OP's question still stands and he's right. There is no good reason that the 5v mods that are being sold are so primitive in terms of power management.

What resistance are you measuring on your 510's, I'm getting about 3.5 ohms. I just saw the TI regs, and you can get free samples if you sign up at TI, so I might play around with those too. I have some transistors rated at around 3A, so I can try those as an outboard pass transistor around the regulator and use the regulator for the voltage as an option to supply more current.

I've got a few circuits in mind (not including the TI one which looks very interesting). Hopefully I will stumble onto something that will work adequately at around 5V.

Thanks for the info and I'll stop hijacking this thread now!

 

[Nuck]

What resistance are you measuring on your 510's, I'm getting about 3.5 ohms. I just saw the TI regs, and you can get free samples if you sign up at TI, so I might play around with those too. I have some transistors rated at around 3A, so I can try those as an outboard pass transistor around the regulator and use the regulator for the voltage as an option to supply more current.

I've got a few circuits in mind (not including the TI one which looks very interesting). Hopefully I will stumble onto something that will work adequately at around 5V.

Thanks for the info and I'll stop hijacking this thread now!

801's usually come in around 3.5ish, 901's (SLB) around 3.0 and 510's (the ones I have) at 2.3 ohm. The 401's I have (they're old) are about 2.7 ohm.

 

[Fairlane64]

801's usually come in around 3.5ish, 901's (SLB) around 3.0 and 510's (the ones I have) at 2.3 ohm. The 401's I have (they're old) are about 2.7 ohm.

That's quite a bit of difference between your 510's and the one's that I have, maybe I'd better check mine against another meter with a calibrated resistor, my Fluke meter might be a bit off on ohms.

Thanks again for the info.

 

[Scottbee]

Genuine Joye 510 attys will be about 2.3 Ohms. The SLB 510 clones will come in at about 3.4.... just like the 901's (give or take .1 Ohm or so).

And to get back to the OP.. yeah, Vregs are a much better solution than simple dropping resistors. And switcher regs are much better than the linears.

 

[Nuck]

I thought I'd add a little bit here. I've been working with the ldo 1.5 amp regs for a bit and using 15270 batteries in a 2XAA box and haven't had any problems with them. I think that where we have intermittent use that even if the draw is a little more than the rating that it doesn't bother them..

I have a new item that I've been probing for a couple of weeks and it's a 5 volt, 3 amp regulator with a control pin.. So it has the functionality of a regulator and a mosfet at the same time. Nice if you want to use a tactile switch and not have to worry about passing 2 amps through it.. Now any switch can drive the control pin without worries.

I could sure use some help with a circuit though.. I'm loaded with 470 ohm resistors so I tie the control pin to ground with a 470 ohm resistor and then run vcc to the pin from the switch.. My concern is that I'm wasting precious ma going through a 470 ohm resistor to ground when the switch is depressed. Maybe a higher resistor is in order?

Any opinions would be greatly appreciated..?

MadVapes LLC is the product and you can see some of the specs there also.

This is a crude schematic I've got going..
View attachment 5509

The resistor values are all 470 ohm.

Hoog

Honestly...if you are worried about a few milliamps then why use a regulator with such a large drop out. The TI one has a drop out of less than 0.5v and will give considerably more life than the ones mentioned in this thread.

If you really want to get the most of your vape, use a switching regulator so wasted power is kept to a minimum.

Plug-in Power Modules - Non-Isolated POL - PTR08060W - TI.com


Personally..I prefer the 1 bat solution with a booster because it allows a USB charging circuit to be added.

 

[Nuck]

Thanks Nuck for mentioning the dropout voltage.. My descriptions were wrong and they have been corrected. The KA378R05 also has a .5v above regulated dropout voltage and I've really got the hots for tactile switches that barely protrude from the face of the mod and the control pin fits the bill for my tactile switch obsession

I see TI family has a version with a control pin also.. I'm going to check into those more.

1 batt, boosted with usb sounds sweet..

Hoog

Yeah..checked the datasheet and it reads 3 amp and <0.5v dropout. The control pin is a nice bonus. At that price its a much better deal than the TI.

Find me a good booster at a lower price than the TI and I'm your biatch for life

 

[jaymcelhone]

If you find a comparable Ti version with free samples offered please post a link here. I am very interested in the regulator with control pin because I also am a big fan of tactile switches. I just love the size and feel of them. A regulator with a built in mosfet at that size is a modders dream com true.

 

[Charged]

This Maxim device looks nice.
Single cell Li-ion step-up 2.5A output adjustable V-out 1.25 - 6V with shut-down/inhibit pin.

MAX1687

 

[jaymcelhone]

This will only deliver up to 2 watts. A 510 atty equals more than 10 watts at 5v at standar 3.7v it is around 6 watts. Ohm's Law Calculators

This Maxim device looks nice.
Single cell Li-ion step-up 2.5A output adjustable V-out 1.25 - 6V with shut-down/inhibit pin.

MAX1687

 

[Charged]

This will only deliver up to 2 watts. A 510 atty equals more than 10 watts at 5v at standar 3.7v it is around 6 watts. Ohm's Law Calculators

Yep my bad,
the 2.5A is for pulsed GSM 12% duty cycle. I should have looked at the data sheet. Looks like the limiting factor is the RDSon of the internal switching N and P channel FETs.

 

[jaymcelhone]

MadVapes LLC KA378R05TU

 

[boondongle]

The linear regulators also waste power as heat. Haven't tried a switching regulator yet, but on paper they should have much better efficiency.

 

[jaymcelhone]

The linear regulators also waste power as heat. Haven't tried a switching regulator yet, but on paper they should have much better efficiency.

Not nearly at the level resistors do.