My First Pulse Width Modulator Mod

[NicksVap3]

ed, i have some pots if you want to try different resistance with that. i have some 100, 10k, 100k and 500k ohm pots... can send you a few

they are multi turn screw type pots BTW, but for testing it should be good enough

 

[Java_Az]

The capacitor between pin 1 and 2 sets the frequency of the 555 i believe. The resistors seem to just give you different parts of the duty cycle as far as adjustability. With no resistors and just the diode i believe you get the full spectrum 0 to 100%. I got room for two of the PWM boards on what i plan to etch. Just need to know how far the pot needs to be moved. you think .050 thousandths of a inch will be enough or maybe a bit more? Not in to big of a hurry i still got a lot of art work to do on mine And a triple check to make sure everything is right , so it will be tonight before I etch.

 

[bstedh]

The capacitor between pin 1 and 2 sets the frequency of the 555 i believe. The resistors seem to just give you different parts of the duty cycle as far as adjustability. With no resistors and just the diode i believe you get the full spectrum 0 to 100%. I got room for two of the PWM boards on what i plan to etch. Just need to know how far the pot needs to be moved. you think .050 thousandths of a inch will be enough or maybe a bit more? Not in to big of a hurry i still got a lot of art work to do on mine And a triple check to make sure everything is right , so it will be tonight before I etch.

I would say the perfect amount to move it back would be a "smidgen"... I don't have anything to measure that small =] Half the width of the dial probably.

 

[bstedh]

ed, i have some pots if you want to try different resistance with that. i have some 100, 10k, 100k and 500k ohm pots... can send you a few

they are multi turn screw type pots BTW, but for testing it should be good enough

I should be good with what I have for now. I don't think going as high as those values would work as they are very high resistance. The highest I plan to try is 1K.

I do greatly appreciate the offer.

 

[bstedh]

I would like to add that the 220K resistor is too much for the LED. It is supper dim. Barley lights up. I am going to put a 220ohm on to see if it burns it out or not. Also on the second board I but the LED on backwards... Another fix for tonight. Or I might stack two 220K's in parallel, I should be able to put them one on top of the other.

 

[Java_Az]

I would like to add that the 220K resistor is too much for the LED. It is supper dim. Barley lights up. I am going to put a 220ohm on to see if it burns it out or not. Also on the second board I but the LED on backwards... Another fix for tonight. Or I might stack two 220K's in parallel, I should be able to put them one on top of the other.

Yeah thats my bad there . I posted a 220k part when it should have been a 220ohm. I am surprised it even lights up at all. Sorry about that . The wheel is .100 so i guess .050 would do the trick.

I got a bunch of 220ohm 0603's here i will send you some with the Rev2 boards.

 

[Java_Az]

Here is revision 2 let me know if you see anything that needs tweeking. I only got the pot to move about .042 thousandths of a inch, not much room on this little board. I think it will be enough. If not we would have to move the output up out of the way. The switch side is some ugly colors now. I changed the output pad on it since in your photos i saw when you drilled it the pad came off. Also got the revised pad for the zener in there.

Edit: And this is just cause i was board , the power of a mint Desktop

 

[bstedh]

The only thing I can think of that would make life easier would be, when you apply the solder mask is to keep a small area leading from the pad un-covered so that I can place the iron on the copper instead of the component.

 

[Java_Az]

The only thing I can think of that would make life easier would be, when you apply the solder mask is to keep a small area leading from the pad un-covered so that I can place the iron on the copper instead of the component.

You talking about everything or is there once component in particular. Solder mask is going to be the grayish black pads and circles. I already fattened the 555 chip pads I would have to make a new footprint if that is where the problem is. Just let me know what needs it and what doesn't and i will see what i can do.

 

[CraigHB]

I also noticed my crap Ultrafire 14500's don't do so well under this load.... They sag real bad. Hopefully the 18350 Trustfires do a better job. Otherwise I may have to spring for some IMR's. Where would be the best place to get them?

I've been getting the IMR cells from Lighthound, decent prices and they ship fast. Though I just checked and they're out of the 14500 IMRs.

You also might want to consider a LiPo hobby battery. The 2S packs (two cells) are amazingly inexpensive from places like Hobbyking and Hobbypartz, somewhat cheaper than two round cells and they have very high drain limits. 20C is low for a hobby LiPo which is way higher than we'd ever need for an e-cig. I picked up a few of the individual ones for making your own packs (I'm using a single cell with a booster). The 2200mAh 20C cells I got have amazingly low internal resistance, under 10mΩ. Doing some load tests with them, I was only getting a 20-30mV drop at 3A. The only thing negative I can say about them is they do have slightly lower charge density (by volume) than a round IMR cell, but it's not a big amount. That's one trade off you get with higher drain, lower charge density.

 

[bstedh]

You talking about everything or is there once component in particular. Solder mask is going to be the grayish black pads and circles. I already fattened the 555 chip pads I would have to make a new footprint if that is where the problem is. Just let me know what needs it and what doesn't and i will see what i can do.

The pad's themselves are fine. Just looking for a little bit of bare copper leading up to the pad to set the iron on. Mostly for the discrete components. The 555 is fine.

This should give you an idea of what I mean...

 

[Java_Az]

This should do it..............

 

[bstedh]

I have my first mock up about done. I just need to figure out what to use for an adjustment lever. Everything else fits good and the voltage looks good. I don't really trust my MM for giving me true Vrms. I can't go above about 3.3Vrms without burning and that is ridiculously hot. Also I am getting crazy plumes of vape. I went with the 500ohm POT as it gives me a little more range which translates into being able to adjust across the vapable range with less movement of the POT. I am going to try the 1K prior to final assembly to see what that does.

I would do a little more with it tonight but I have to get some work done on the SGV3 co-op.

 

[romaniac]

I have my first mock up about done. I just need to figure out what to use for an adjustment lever. Everything else fits good and the voltage looks good. I don't really trust my MM for giving me true Vrms. I can't go above about 3.3Vrms without burning and that is ridiculously hot. Also I am getting crazy plumes of vape. I went with the 500ohm POT as it gives me a little more range which translates into being able to adjust across the vapable range with less movement of the POT. I am going to try the 1K prior to final assembly to see what that does.




I would do a little more with it tonight but I have to get some work done on the SGV3 co-op.

It looks splendid!!!!!!!!!!!!!!!!

Romaniac

 

[jrm850]

Great Stuff Bstedh!

is this your circuit?

Circuit Simulator Applet

 

[bstedh]

Great Stuff Bstedh!

is this your circuit?

Circuit Simulator Applet

I think that is a variable frequency circuit and not a PWM circuit. PWM uses a fixed frequency square wave with varied on duration. Of course without an O-scope I can't be sure how the circuit we are using is in fact reacting. That has about the same components but in a slightly different configuration.

Edit: Also just to clarify this is not my circuit =] Asnider and Clutch have done most of the leg work on this thing. I am just miniaturizing it. =]

 

[asnider123]

It is a PWM, if you change the POT, it changes the duty cycle, but the frequency remains at at approx 400-500 cycles .. incidently that program is the mack daddy!!!! 220 ohm resistor and 1K pot, 1 cap and 1 diode .. what a simple circuit!!! I love it Tie a MOSFET to the output and you got it! Since it gives you positive pulses, you need an n-channel fet ... Man, if I was not so tied up with work, I would love to give this another shot, you guys are wizards, I mean it!!

Alan

I think that is a variable frequency circuit and not a PWM circuit. PWM uses a fixed frequency square wave with varied on duration. Of course without an O-scope I can't be sure how the circuit we are using is in fact reacting. That has about the same components but in a slightly different configuration.

Edit: Also just to clarify this is not my circuit =] Asnider and Clutch have done most of the leg work on this thing. I am just miniaturizing it. =]

 

[jrm850]

Glad to see it working. How does it vape ? Was pretty sure i transferred the circuit over to SMD correctly. I guess SO far the pot just needs to be moved forward a little bit. I might be etching again later today so let me know if you want a rev. 2 board or two. The slow boat from china finally came in Saturday and i got my 100 Ultra Bright UV LED's. So solder masking should go much smoother now. I whipped up this board yesterday, soldering 100 LED's is so much fun.

I just ordered a bunch of UV LEDs for cheap but they appear to be standard 20mw 3.2v LEDS. Will these work given enough exposure time? They can't tell me the MCD#.
I'm thinking about converting an old scanner housing.

 

[Java_Az]

I just ordered a bunch of UV LEDs for cheap but they appear to be standard 20mw 3.2v LEDS. Will these work given enough exposure time? They can't tell me the MCD#.
I'm thinking about converting an old scanner housing.

I was using just a UV sanitation wand and it was taking a hour to a hour and 15 mins to cure the ink. With the LED's I Rigged up it has cut the time to about 20 minutes. But i also have to run the LED's @ about 3.3 volts or my Regulator board starts screaming. If i can get them to 3.6 or 3.7 volts i think i could get the cure time down to 10 or 12 minutes. Data sheet on the UV ink says 10 minutes but that's under some really strong industrial UV lights. So i am not too far off of what it should be taking. Nice thing about the UV LED's is that they are directional the light comes out the top between 15 to 30 degrees pattern. The ones i got are rated at 20 - 25 degrees. Here is a link to the ones i ordered. 4.8 cents a peice shipped is not bad. Although if i had to do it over i would go with some 5mm ones and pay a bit more and solder a bit less. I also put mine on .300" centers so they are fairly close together. But to answer your question what you got should work for you as long as they are UV .
100 3mm 2 Pin UV/ Purple LED Light Lamp Bright 5000 Mcd - eBay (item 140576352356 end time Aug-11-11 00:18:05 PDT)

 

[jrm850]

I was using just a UV sanitation wand and it was taking a hour to a hour and 15 mins to cure the ink. With the LED's I Rigged up it has cut the time to about 20 minutes. But i also have to run the LED's @ about 3.3 volts or my Regulator board starts screaming. If i can get them to 3.6 or 3.7 volts i think i could get the cure time down to 10 or 12 minutes. Data sheet on the UV ink says 10 minutes but that's under some really strong industrial UV lights. So i am not too far off of what it should be taking. Nice thing about the UV LED's is that they are directional the light comes out the top between 15 to 30 degrees pattern. The ones i got are rated at 20 - 25 degrees. Here is a link to the ones i ordered. 4.8 cents a peice shipped is not bad. Although if i had to do it over i would go with some 5mm ones and pay a bit more and solder a bit less. I also put mine on .300" centers so they are fairly close together. But to answer your question what you got should work for you as long as they are UV .
100 3mm 2 Pin UV/ Purple LED Light Lamp Bright 5000 Mcd - eBay (item 140576352356 end time Aug-11-11 00:18:05 PDT)

I paid 4 trimes as much, but they were 200 miles away from me and my need for instant gratification took over.

The ones I ordered are supposedly below the visible spectrum (380nm) so they are rated in mw intead of Mcd. they are only 6mw so my setup will probably be a heck of a lot slower than yours.

How do you know when the board has been exposed long enough? Are there any visible indicators? I've been pretty much unsucsessful with presensitized boards to date, but your fabulous boards are inspiring so I'm going to give it a another go for a cool touchscreen project I'm working on.

I don't have much time to work on mods so if one of you propeller hat wearing geniuses want to build the ultimate touchscreen PV, I'll post my code when it's finished.

this is the GLCD I'm using: 128x64Q ALL-IN-ONE TOUCHSCREEN GLCD With RGB LED BACKLIGHT