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If you do not want to use the N/C fire switch on pin 2, and you still want want a safety switch, you can add a slider switch (or use the built in box slider switch) to the battery like below.
I just made one like this using the switch that came with the box. I know that the built in box switch it not a high quality switch.
My thoughts about using the built in switch are this....
1. You will only use the switch at the beginning and end of a vap session, so the switch will not get as much use as the fire switch.
2. You will only slide the switch when there is no load on it. With the fire switch still open the current going through the safety switch will be very low and no arcing will happen.
3. The only time this switch will see high current is when it is already close and you hit the fire switch. This should help to reduce the wear on the contacts.
4. I might be totally wrong about this, but I am going to use it this way for a bit and see what happens.
Attachments
Only problem I see is now your fire switch is seeing alot higher amps. This means you can not use a .5ma switch and the fire button will burn out faster. Whereas the other way you dealing with ma vs Amps on the original circuit. That would be the same as having no safety switch and running all that amperage through the fire switch. If you are going to use a safety switch then I would go back to the original circuit IMO.
Dan
The simple answer is....this chip has a dropout of around .5 volts. So to get 8.5 out you need a 9 volt supply.
Stoned... the wiring is different for the fire switch if you're not using a master on/off switch.
The way I wired my mod without a master on/off switch was one leg of the switch you're using goes to pin 1 (Vin) of the LDO and the other leg of the switch goes to the Batt + contact. And make sure you have an NO switch, not an NC switch.
Good stuff here, I'm 1.5 years behind on this, building it only now.
Few questions:
If using 3A switch can I avoid 10uF caps?
Or these 10uF caps are used to control\smooth out the current so the 200k POT will not get damaged?
If 10uF Caps are used for a tiny .5A switch then using my 3A switch I should be able to avoid the Caps, correct?
Just want to keep this as simple as possible.
Thank you in advance!
It's up to you, leave them off if you want. The caps have nothing to do with the type of switch or the way the pot functions. There are many designs on these forums that ignore spec sheet recommendations and still kinda work.
It's like Willy said - the caps are not there for the switch or the pot. They're there for the regulator.
I've seen some modders not use caps and they have no problems. But Blue had said he had inquired from the manufacturer of this regulator if caps are needed in our applications and was told caps are recommended as the regulator may not last as long without caps as it would with caps. Less stress on the regulator to have caps.
I think you may be confusing a cap with a mosfet when talking about a 3A switch vs a 0.5A switch. A mosfet is used in line with a 0.5A switch to take the load off the switch. A 3A switch can easily handle the atty load, but not a 0.5A switch. So a mosfet is usually required when using lower amp switches unless you want to repeatedly replace the switch when it fails.
And I would add that although the mosfet relieves the heavy amp load, it's no excuse to use a 50¢ switch, which is mechanically inferior and is not meant for the kind of constant pressing we tend to do.
Spending $3+ usually makes for a well built, branded switch.
Digi-Key - GH1349-ND (Manufacturer - 39-401 BLK)
This is the switch Nuck lists for his well engineered, mosfet equipped, FistPack.
Thank you both WillyB & Mamu for a quick reply,
Thank you for clear explanation.
(1 hour later)
Placed all parts on a bread board to test,
3A switch
Incoming voltage from 2 x 14500 = 8 volts (fully changed)
Set the POT to voltage out to 4.5
Attached carto at 2.8 Ohms.
Every looked good and was exited! But after a few puffs it seems like the UCC283T-ADJ is overheating very fast, just killed two of them.
SO maybe I should use the 10uFcaps anyway?
Thank you for clear explanation.
(1 hour later)
Placed all parts on a bread board to test,
3A switch
Incoming voltage from 2 x 14500 = 8 volts (fully changed)
Set the POT to voltage out to 4.5
Attached carto at 2.8 Ohms.
Every looked good and was exited! But after a few puffs it seems like the UCC283T-ADJ is overheating very fast, just killed two of them.
SO maybe I should use the 10uFcaps anyway?
...But after a few puffs it seems like the UCC283T-ADJ is overheating very fast, just killed two of them.
SO maybe I should use the 10uFcaps anyway?
I don't think those small caps will help much with drawing the heat away from the regulator. Did you attach a heat sink to the regulator?
I use this one that I buy at digikey: HEAT SINK TO-220 .250" COMPACT
No I did not Mamu, I did not realize why it was there for by the OP, since my standard 5v seems to handle 8v coming in and 5v out to atty and 3 or less to the heat.
I re-read this post and acquired a heat sink from an old PC video card
which I will cut into a smaller size and try to attach.
The link to your heat sink looks a lot better and looks like it is made right for the regulator, I will buy me some.
Thanks again for the help Mamu,
Still learning as I go along.
I re-read this post and acquired a heat sink from an old PC video card
which I will cut into a smaller size and try to attach.The link to your heat sink looks a lot better and looks like it is made right for the regulator, I will buy me some.
Thanks again for the help Mamu,
Still learning as I go along.
Edited because i need to confirm my statments. Will post back on the issues discussed when confirmation is complete - sorry to interupt
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Try flipping the pot around 180 degrees. The 3 pin connect of a pot (as noted), for the most part, is unconventional and may present some problems. One way or the other you may be asking the chip to do something it simply can't with what you provide it (being voltage as well as amperage) . I've found it BEST to use a fixed resistor in the R2 position and a pot in the R1 rather than connecting as suggested. Some like, or will use, a fixed Resitor in the R1 position. Do the calculations and find what WORKS for what you are using (atty AND battery wise).
I do know this -- placing a 82.5K Resister in the R2 position and a 500K pot in the R1 position you will get an adjust range from 3.4ishV and up quite nicely. You'll need a heat sink if you run LR atties tho -- I run mostly HR due to my scrupples in not trying to drawing blood from a turnip as in trying to pull 2 amps from a 1.5 amp battery.....
Note too - The further away you are between the VI and VO the hotter this chip will get. The high wattages will create the same result IF your are in the higher amperage ranges of the chips specs. IE: The chip runs VERY cool at 10 watts with 8V in and 7v Out vs 10 Watts at 8v in and 3.8 out -- Big difference - at least from my experience and calculations. Dissipation is what all the heat is about in addition to - perhaps - dividing by Zero lol - as may happen in some configurations like what you may have.
Can't recall ALL my tests - but one my calcs indicated I was in the negative ohmic requiremnts of the chip (according to specs) and FOR REAL - I could've lit a regular cigeratte off that chip - no chit!
Be safe folks -- and never follow someone in the (a) fog....... IE Know WHY you are doing it! NOT just because others are.......
I do know this -- placing a 82.5K Resister in the R2 position and a 500K pot in the R1 position you will get an adjust range from 3.4ishV and up quite nicely. You'll need a heat sink if you run LR atties tho -- I run mostly HR due to my scrupples in not trying to drawing blood from a turnip as in trying to pull 2 amps from a 1.5 amp battery.....
Note too - The further away you are between the VI and VO the hotter this chip will get. The high wattages will create the same result IF your are in the higher amperage ranges of the chips specs. IE: The chip runs VERY cool at 10 watts with 8V in and 7v Out vs 10 Watts at 8v in and 3.8 out -- Big difference - at least from my experience and calculations. Dissipation is what all the heat is about in addition to - perhaps - dividing by Zero lol - as may happen in some configurations like what you may have.
Can't recall ALL my tests - but one my calcs indicated I was in the negative ohmic requiremnts of the chip (according to specs) and FOR REAL - I could've lit a regular cigeratte off that chip - no chit!
Be safe folks -- and never follow someone in the (a) fog....... IE Know WHY you are doing it! NOT just because others are.......
OH yea and a BIG thank you to BigBlue30, without him I would have never even built the mod.
A similar, though overpriced, one can be found at RS.I don't think those small caps will help much with drawing the heat away from the regulator. Did you attach a heat sink to the regulator?
I use this one that I buy at digikey: HEAT SINK TO-220 .250" COMPACT
TO-220 Heat Sink - RadioShack.com
Ok so I wired this up based off willy and mamus pics. Seemed everything was going fine. Flipped the on off switch to on. Hit the fire button and the led lit up. Yay. Then attached a carto and tried to hit it. No light, no hit, nothing. Took off the carto and hit the switch and lights away. Tried testing it with no carto on my multi meter and got anywhere from 1.21v to 5.85 volts. For some reason whenever I connect a carto or atty it won't work even though it works fine without one. Any suggestions?
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