Easy eGo-esque pwm performance

[Fenix-T]

On my iPod so I gotta keep it short. I'm looking for a simple 555 pwm layout. That has volt in and volt out to atty so it's easy to add to any circuit. I'm not even looking for it to be variable. Just comparable or a bit better to the ego. So that makes me wonder what's a good duty cycle to go with? I could use a resistor instead of a pot for a fixed cycle. I just need to make efficient waves for smooth steady vaping.

I'm in the middle of making a mod(I'll post pics when finish) so this will be in my next one. Thanks all!

 

[Java_Az]

This 555 PWM is what i had the best luck withDPRG: A Simple PWM Circuit Based on the 555 Timer. For sure the pot could be replaced with a resistor when you Know the duty cycle you like the best.

 

[Fenix-T]

This 555 PWM is what i had the best luck withDPRG: A Simple PWM Circuit Based on the 555 Timer. For sure the pot could be replaced with a resistor when you Know the duty cycle you like the best.

Thanks, that's a start. I guess I cooouullld break it down like I need it, but I was hoping to copy someone else's homework, lol. I guess I would need to breadboard it anyway if I was going to use a pot to find the resistance I need, then put that in a mod. Would be nice to have x ohms is 50%, ect. That's a whole project on it's own. So much more work than my original plan to hit my button super fast. Guess it's gotta be done, though.

Has anyone else notice how fast an atty is in need of a cleaning while on straight DC? I'm talking I have to dry burn and everything.

 

[Java_Az]

Here is a thread about using the 555 as a PWM http://www.e-cigarette-forum.com/forum/battery-mods/194095-my-first-pulse-width-modulator-mod.html

I tried out the last circuit posted in the thread , but The one i posted in here seemed to give me a much wider duty cycle i could go from 20% to 100% with it. in the end i like the vape off a switching module with stacked batteries better. This could work nicely for a single battery though which sounds like what your going for.

 

[Fenix-T]

Yeah, single cell. Do you mean a PWM is better on single cell?

EDIT: Yeah, that link helped alot, thanks! I read that one earlier but the pics didn't show on my ipod ?

 

[Java_Az]

Yeah i think thats what the ego's and all the knock offs run is some sorta PWM. It does work for stacked cells too but the switching modules i have been using are really stable , I think i get a more consistent vape off them. Sure they cost more but you get a really finely tuned module in a small space. Here is a pic of the murata one alot of folks are using

Texas Instruments also makes some that are almost the same.

Edit: Here is the mouser image much sexyer

 

[Fenix-T]

Are you having any heat issues with it? How's the efficiency?

Ah, nvm, just seen the input voltage for em. Sexy chip though.

 

[CraigHB]

Yea, it's a .....en part, to use an old expression, hehe. Onboard capacitors and very high efficiency, you won't do better.

You can get a few percent higher efficiency with PWM, but the buck regulator is much easier to use since you can just plug it in and pop a voltmeter on there if you want.

 

[WillyB]

The problem I see with the basic PWM circuits is how do you adjust as the cells drop in voltage. With regulated voltage going in it's fine. If you wanted to maintain 4V while vaping you would have to be constantly adjusting the duty cycle as the cells discharged. No?

 

[CraigHB]

And therein lies the rub. Indication is difficult with PWM and as battery voltage drops, you need more duty cycle to compensate. Not a trivial matter to do that automatically.

 

[bstedh]

I have that worked out... I am going to use a thumb-wheel pot with a lever attached that will stick out of the body so that you can adjust it like you would a cigarette lighter. Yes you have to adjust it but it is very easy to do...