What part is failing? The IC ? Does it get hot? Drawing too much current from it perhaps? Power supply is smoth and suitable for the IC?
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What part is failing? The IC ? Does it get hot? Drawing too much current from it perhaps? Power supply is smoth and suitable for the IC?
It is about darn time! I got the board to work. It is the ugliest solder job I have seen, but it was tough to keep the heat in the huge pads I had to make to get rid of the parasitic capacitance issue.
The touch switch also works.
Here is a picture of the ugliness:
The touch switch also works.
Here is a picture of the ugliness:
It is about darn time! I got the board to work. It is the ugliest solder job I have seen, but it was tough to keep the heat in the huge pads I had to make to get rid of the parasitic capacitance issue.
The touch switch also works.
Good news.
Do you find the touch switch is easy to use and consistent? Was it based on two FETs or one in the end? And what is the current flow in the atomizer coil when the switch is off?
Yeah, I think it was the IC. The parasitic capacitance was shorting it out. It explains why everything would checkout out OK before I put power to the circuit. After powering up, it was dead.
Funny thing is on this latest board, I plugged the battery in and checked evrything out and all was good. I had the board ob my lap and felt it getting warm. For some reason the IC was getting really hot. I couldn't find any jumpers or cold welds, so I decided to get the Dremel out and cut off the IC.
After grinding and cleaning up my board, I soldered on the last IC I had, crossed my fingers, and threw the power to it. Low and behold it worked, and no hot IC. I must have had a short somewhere.
I went with the single mosfet. The current is zero when measured across the atomizer leads when the switch is off. The switch seems to be consistant. It is pressure sensitive though. If you just barely touch the leads, you will only get a couple of volts going to the atomizer. Not much pressure is required to produce the 5V output.
I think the parasitic capacitance was a red-herring; this would only be expected to affect high frequency circuitry.
Re mosfet: that's great to hear - 1 is enough for both sensitivity and sufficient current; even better, no off-current; that's the beauty of the FET combined with MOS
Not sure if you saw my idea thread about putting the contacts into the mouthpiece; that is looking like a winner - especially with the contacts embedded so the finish is smooth; a flattened mouthoiece would be best of course. The idea could be prototyped using foil (and insulated where necessary with sellotape/vinyl tape underneith. It's the next step in convenience
I kmow your meaning! Anyone who has worked with relays will know it. You might also know if from the sound generated when pushing the button for fog lights etc in your car.
Although I think a MOSFET is the best way to go here, it might be worth considering adding a click sound via an acoustic transducer ... The audio feeback would be nice. Or the faint hum (more tactile than aural) of a miniature fan, as I have proposed elsewhere, that assists with the puff and ensures air flow for cooling purposes.
Ahhhhhh! Stupid Thing! It is dead now. Who knows why, but I going to do a redesign and use a different boost converter that uses external mosfests for the switching.
Hey kinabaloo, I did see your post about the touch switch on the mouth piece. My only personal issue with that is I tend to have the mouth piece on my lips even when I am not vaping. Must be a remnant from always holding my analog in my mouth as well. I like the idea and it should work well.
Before my IC died I was checking out the touch switch with it hooked up to the actual touch posts and it was not as pressure sensative as I thought. A very light touch would put out the 5V. When I tested it before, I was just closing the switch by putting my finger across the traces on the board which were in a pretty tight spot. So it was probably due to trying to get my fat finger in there.
Anyway, I need to do some more research and get some parts on order.
Oh, one last thing. How would I go about adding a low voltage alarm? What I want is an LED to come on when the battery voltage drops to 3 volts. That way, you are not all of a sudden sitting there with a dead battery and you left your charger at home. That is the only problem with the constant output mods...no warning before they go dead.
Hey kinabaloo, I did see your post about the touch switch on the mouth piece. My only personal issue with that is I tend to have the mouth piece on my lips even when I am not vaping. Must be a remnant from always holding my analog in my mouth as well. I like the idea and it should work well.
Before my IC died I was checking out the touch switch with it hooked up to the actual touch posts and it was not as pressure sensative as I thought. A very light touch would put out the 5V. When I tested it before, I was just closing the switch by putting my finger across the traces on the board which were in a pretty tight spot. So it was probably due to trying to get my fat finger in there.
Anyway, I need to do some more research and get some parts on order.
Oh, one last thing. How would I go about adding a low voltage alarm? What I want is an LED to come on when the battery voltage drops to 3 volts. That way, you are not all of a sudden sitting there with a dead battery and you left your charger at home. That is the only problem with the constant output mods...no warning before they go dead.
Ahhhhhh! Stupid Thing! It is dead now. Who knows why, but I going to do a redesign and use a different boost converter that uses external mosfests for the switching.
Hey kinabaloo, I did see your post about the touch switch on the mouth piece. My only personal issue with that is I tend to have the mouth piece on my lips even when I am not vaping. Must be a remnant from always holding my analog in my mouth as well. I like the idea and it should work well.
Before my IC died I was checking out the touch switch with it hooked up to the actual touch posts and it was not as pressure sensative as I thought. A very light touch would put out the 5V. When I tested it before, I was just closing the switch by putting my finger across the traces on the board which were in a pretty tight spot. So it was probably due to trying to get my fat finger in there.
Anyway, I need to do some more research and get some parts on order.
Oh, one last thing. How would I go about adding a low voltage alarm? What I want is an LED to come on when the battery voltage drops to 3 volts. That way, you are not all of a sudden sitting there with a dead battery and you left your charger at home. That is the only problem with the constant output mods...no warning before they go dead.
What's the 'boost converter' for? I forgot.
If you PM the circuit I can try to identify where the design might be failing; if want to keep it secret, no worries.
Voltage getting low detection: op-amp comparator; reference voltage from resistor split, across zener; so, from battery positive before regulator, resistor to feed zener (value say 1V less than the regulated voltage) then across zener 2 resistors to divide zener voltage to get desired reference voltage (for alarm); the op-amp other input is a resistor splt from batter also, no zener this time. So you are comparing say 1/2 the battery voltage with 1/2 the desired alarm voltage; the 1/2 is a trick I though of to make this possible
If the opamp o/p current is not sufficiently rated to drive the buzzer, feed a suitable transistor (a BC109 might be able to handle a low-current buzzer); perhaps an LED would be better.Alright. It has been a little while, but I did a complete redesign using a new boost controller chip that uses external mosfets (actually two of them) instead of an internal one. I also added a small, itty bitty, teeny tiny, chip that is a supervisory IC. It monitors the battery voltage and when the voltage falls below 3V it turns on an LED. The chip is about 3mm long and 1.5mm wide and has 5 pins. It is in the upper left corner of the attached picture.
So the good news is that the circuit is working, and is continuing to work. It is boosting the 3.7V nominal from the LI-Poly battery to 4.99V at the atomizer. I will have to wait and see if the low voltage light comes on. I have stepped up my vaping to try to wear down the battery faster, but I have only managed to reduce it from 4.1V to 3.98V in 24 hours. It may take a while. I also have to test to see if the charging circuit works.
The bad news is that the touch switch is a no go at this point. I have a tactile switch wired in for the interum until I figure it out. The circuit is there, and I am using it when activating the tactile switch to fire the mosfet switch. When trying to do the touch switch, I could not get enough voltage to the mosfet gate to get it to allow current to flow. I could generate 1.2V from the 4.1V battery. I am using a logic level gate mosfet with a spec minimum gate threshold of 1V, but the specs don't list a typical or max required voltage.
In the other circuit where I had the touch switch working, I was tapping the 5V output from the boost converter to fire the mosfet switch. That worked well, but what I think one of my problems was that I was running the boost controller all the time and just switching the atomizer ground with the mosfet. The IC's do not have a 100% duty cycle, so that is what may have been causing my board to all of a sudden not work.
So on this board, I am using the mosfet to switch the ground to the entire circuit, so all I have available to tap into for the touch switch is battery voltage.
Hey kinabaloo, if my duty cycle is listed as 94%, does that mean the IC just boosting the voltage with no load, or does the duty cycle only count when a load is applied.
I will get some pictures posed of the actual assembly soon. But for now, here is the "pretty" picture of the new board. The actual one looks a mess, but it works.
So the good news is that the circuit is working, and is continuing to work. It is boosting the 3.7V nominal from the LI-Poly battery to 4.99V at the atomizer. I will have to wait and see if the low voltage light comes on. I have stepped up my vaping to try to wear down the battery faster, but I have only managed to reduce it from 4.1V to 3.98V in 24 hours. It may take a while. I also have to test to see if the charging circuit works.
The bad news is that the touch switch is a no go at this point. I have a tactile switch wired in for the interum until I figure it out. The circuit is there, and I am using it when activating the tactile switch to fire the mosfet switch. When trying to do the touch switch, I could not get enough voltage to the mosfet gate to get it to allow current to flow. I could generate 1.2V from the 4.1V battery. I am using a logic level gate mosfet with a spec minimum gate threshold of 1V, but the specs don't list a typical or max required voltage.
In the other circuit where I had the touch switch working, I was tapping the 5V output from the boost converter to fire the mosfet switch. That worked well, but what I think one of my problems was that I was running the boost controller all the time and just switching the atomizer ground with the mosfet. The IC's do not have a 100% duty cycle, so that is what may have been causing my board to all of a sudden not work.
So on this board, I am using the mosfet to switch the ground to the entire circuit, so all I have available to tap into for the touch switch is battery voltage.
Hey kinabaloo, if my duty cycle is listed as 94%, does that mean the IC just boosting the voltage with no load, or does the duty cycle only count when a load is applied.
I will get some pictures posed of the actual assembly soon. But for now, here is the "pretty" picture of the new board. The actual one looks a mess, but it works.
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