I made this circuit and tried to figure out a simple way to regulate the charge voltage to a capacitor (a big capacitor)
to limit the voltage somewhere below 2.7v but above 2v
and came up with this
http://tinyurl.com/n5mbx8a
but it obviously has some problems being theres no precise cutoff
it charges at constant current depending on your supply current limiter until a certain point (12v seems to charge the capacitor well. but lower voltages can probably work too)
down to mA then uA and the voltage slowly rises to nearly 2.7v but it takes a long time
I was thinking of using it to charge my super capacitor (100 farads) really consistantly
I've got all the components except the zener diode
my transistors are NPN and PNP same type and 95 to 105W max rating and i've got a big heatsink I can use for them.
as far as I can see it should work. (as long as the zener diode is not out of spec too much)
Is this an interesting circuit design or no?
Hit reset to reset the simulation and play with the speed to see how it operates.
its not a download but an online real time circuit simulation.
to limit the voltage somewhere below 2.7v but above 2v
and came up with this
http://tinyurl.com/n5mbx8a
but it obviously has some problems being theres no precise cutoff
it charges at constant current depending on your supply current limiter until a certain point (12v seems to charge the capacitor well. but lower voltages can probably work too)
down to mA then uA and the voltage slowly rises to nearly 2.7v but it takes a long time
I was thinking of using it to charge my super capacitor (100 farads) really consistantly
I've got all the components except the zener diode
my transistors are NPN and PNP same type and 95 to 105W max rating and i've got a big heatsink I can use for them.
as far as I can see it should work. (as long as the zener diode is not out of spec too much)
Is this an interesting circuit design or no?
Hit reset to reset the simulation and play with the speed to see how it operates.
its not a download but an online real time circuit simulation.
> A real super cap would have significant internal resistance
I remember a hundred ohms. Apparently a current 100F cap is 0.01 Ohms max.
> reaches full charge after only a minute or so
From dead flat? Or from some Volts?
Taking 100F and 0.75A, I get 356 seconds (6 minutes) from zero to 2.7V. (This agrees with Mooly's number for 1A.)
92 seconds "a minute or SO" from 2.0V to 2.7V.
Simulation shows a 0.75A current source, voltage-limited to around 2.7V. The voltage control is crude so the switchover from full current to no current is very soft with a long tail. I could make that smarter, but why? To get the 2.7V point I let it run over 5V and cursored the 2.0V and 2.7V times.
I remember a hundred ohms. Apparently a current 100F cap is 0.01 Ohms max.
> reaches full charge after only a minute or so
From dead flat? Or from some Volts?
Taking 100F and 0.75A, I get 356 seconds (6 minutes) from zero to 2.7V. (This agrees with Mooly's number for 1A.)
92 seconds "a minute or SO" from 2.0V to 2.7V.
Simulation shows a 0.75A current source, voltage-limited to around 2.7V. The voltage control is crude so the switchover from full current to no current is very soft with a long tail. I could make that smarter, but why? To get the 2.7V point I let it run over 5V and cursored the 2.0V and 2.7V times.
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5V _CT_ heater winding, say 3 Amps. Two BIG (30A) diodes. Full-wave-CT power supply. Right to the supercap.
The nominal DC voltage will be 2.5V*1.414, minus some-tenths for diode.
At turn-on, the huge cap will SUCK current BIG time. But the cap is rated for 10A continuous and 70A surge. The 3A winding can't put much over 30A into a short, and current will drop as the cap voltage comes up. Yes, the transformer will want to get hot. But 100F is not an infinite hole. In less than a minute current will be quite small as the cap comes up to peak AC voltage. 5V 3A transformers won't burn-up that fast.
Yes, it will dribble on and on, and probably rise over the 3.0V rating. You could maybe use a 60 second timer-- will never take longer than that. Or a 2.7V-2.9V threshold detector and relay, though powering this stuff will want an additonal power supply.
Are you really in a hurry? 12V through 1K with a 2.7V Zener across the cap will charge from 2.0V to 2.7V in 2 hours, zero to 2.7V overnight. No heat, no risk of explosion.
The nominal DC voltage will be 2.5V*1.414, minus some-tenths for diode.
At turn-on, the huge cap will SUCK current BIG time. But the cap is rated for 10A continuous and 70A surge. The 3A winding can't put much over 30A into a short, and current will drop as the cap voltage comes up. Yes, the transformer will want to get hot. But 100F is not an infinite hole. In less than a minute current will be quite small as the cap comes up to peak AC voltage. 5V 3A transformers won't burn-up that fast.
Yes, it will dribble on and on, and probably rise over the 3.0V rating. You could maybe use a 60 second timer-- will never take longer than that. Or a 2.7V-2.9V threshold detector and relay, though powering this stuff will want an additonal power supply.
Are you really in a hurry? 12V through 1K with a 2.7V Zener across the cap will charge from 2.0V to 2.7V in 2 hours, zero to 2.7V overnight. No heat, no risk of explosion.
Well in real life it charges up from 0v to 2.7v in a minute or so at 0.75A FOR ME
I must have a fake super capacitor rated only 10F internally or something then! It does feel substantionally light.
Maybe its somewhat more than 10F maybe 20 but possibly not 100F?
because ive seen it only takes 6 400F super capacitors to start a car by themself. for at least 1 jumpstart.
Also noticed it takes and holds a charge up to 3.1v for enough time to be useable tens of minutes.
(Doesnt change temperature at all when charged even up to 3.4v at 0.75A it must be fake or knock off of some original brand.)
Charged up to 2.75v it takes a night or two to drop to 2.49v
And I wouldn't use a transformer to charge it from.
I'd use a regulated current limited power supply from 5 to 12 volts max voltage output of it. with about 1 to 3 amps limiting current (depending on transistor your using. I used a NPN/PNP combination to limit the losses and make it as simple as possible.) Going to my circuit that i designed (Possibly with tweaked components and a LED that lights up green when its finished charging)
so the capacitor only gets a max of 1 to 3 amps even when starting at 0v
The 1K resistors are to limit current through the resistors and zener to prevent excess current lost in the resistors and the zener diode. Of course you could use 500ohm or 220ohm resistors but that would simply waste curent and not really charge it any faster.
I must have a fake super capacitor rated only 10F internally or something then! It does feel substantionally light.
Maybe its somewhat more than 10F maybe 20 but possibly not 100F?
because ive seen it only takes 6 400F super capacitors to start a car by themself. for at least 1 jumpstart.
Also noticed it takes and holds a charge up to 3.1v for enough time to be useable tens of minutes.
(Doesnt change temperature at all when charged even up to 3.4v at 0.75A it must be fake or knock off of some original brand.)
Charged up to 2.75v it takes a night or two to drop to 2.49v
And I wouldn't use a transformer to charge it from.
I'd use a regulated current limited power supply from 5 to 12 volts max voltage output of it. with about 1 to 3 amps limiting current (depending on transistor your using. I used a NPN/PNP combination to limit the losses and make it as simple as possible.) Going to my circuit that i designed (Possibly with tweaked components and a LED that lights up green when its finished charging)
so the capacitor only gets a max of 1 to 3 amps even when starting at 0v
The 1K resistors are to limit current through the resistors and zener to prevent excess current lost in the resistors and the zener diode. Of course you could use 500ohm or 220ohm resistors but that would simply waste curent and not really charge it any faster.
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leakage to capacitance ratios for ordinary capacitors are so low that a slightly leaky electrolytic stores charge for days and weeks and months.
Each measurment sucks out a little bit of charge.
But try a 63V 4700uF cap. Charge it to 60V and then check the stored voltage after 7days.
Are supercaps different?
I've found small capacitors like 1000uF 16v can be charged to 24v+ and hold the charge without dropping voltage from leakage (if it is. its too slow for my multimeter to detect!)
5 minutes later it was still at 24.70v
and when I first charged it it was 24.71 (which was probably just from the internal resistance changing right after it finished charging from being charged up)
I shorted my 100F super capacitor to a small metal precision screwdriver head (not the shaft but the end of the shaft where its thinner
about 1mm to 4mm thick and it glowed orange yellow pretty good for a few seconds.
capacitor was ever-so-slightly warmer near the top.
was only charged to 2.4v or so. not even close to its max possible charge level
imagine if i charged it to 3.1v and did the same thing.
it would probably incinerate the same screwdriver in a shower of sparks and white searing hot metal
i did get a small spark
The leads of the super capacitor didn't heat up much (Probably because they were coated in enough solder to make them carry more current)
Solder on them didn't melt.
I wonder how the screwdriver can be slightly thicker but the leads of the capacitor don't even get warm!
Must be some new form of copper or silver or something! (they are really hard so I dont think they're copper. unless they are tempered/treated to be very hard like heat up to hot temperatures then dunk in water for certain amount of time.)
5 minutes later it was still at 24.70v
and when I first charged it it was 24.71 (which was probably just from the internal resistance changing right after it finished charging from being charged up)
I shorted my 100F super capacitor to a small metal precision screwdriver head (not the shaft but the end of the shaft where its thinner
about 1mm to 4mm thick and it glowed orange yellow pretty good for a few seconds.
capacitor was ever-so-slightly warmer near the top.
was only charged to 2.4v or so. not even close to its max possible charge level
imagine if i charged it to 3.1v and did the same thing.
it would probably incinerate the same screwdriver in a shower of sparks and white searing hot metal
i did get a small spark
The leads of the super capacitor didn't heat up much (Probably because they were coated in enough solder to make them carry more current)
Solder on them didn't melt.
I wonder how the screwdriver can be slightly thicker but the leads of the capacitor don't even get warm!
Must be some new form of copper or silver or something! (they are really hard so I dont think they're copper. unless they are tempered/treated to be very hard like heat up to hot temperatures then dunk in water for certain amount of time.)
I tested it and it still holds a charge just fine (it wasnt a complete short. the screwdriver was glowing so it was probably under 50 amps for sure. and only lasted a second or so.
I modified a 1A normal and 3A max boost converter that boosts from 2.8v to 30v input
up to 48v
I swapped out the inductor for a toroidal one with thicker wire
And now it happily outputs over 5 and a half amps
boosts a 6v AGM SLA battery up to 12v to run a small 400W power inverter (to run a small load like a phone charger. not running a washing machine or anything like that from it!)
it spiked at a max of 6A and didn't cut off or go into protection mode
so it seems to absolutely love the new inductor i soldered onto it
the original inductor was 470uH
I hand re-wound a copper wire into the toroid and at 1A to 3A the inductor barely gets warm
whereas before it would get SEARING HOT at only 1A!
And I know boosting a 6v 5AH AGM SLA up to 12v is pointless
but I have two 6v SLA AGM 5AH batteries. and a 12v SLA AGM 5AH battery
I was just testing its capabilities
it seems it works great for boosting the super capacitor up to run my 250W class D audio amplifier (only running at 1-6 watts max because i have tiny speakers)
and it lasts a good long time. about 10-15 minutes with 5-10 minutes of continuous use at medium-high volume maybe more if I only boost it up to 4.5v
I do have to charge the super cap up to at least 2.8v to 3v to get it to run the boost converter. but the super capacitor doesnt seem to mind
I need to heatsink the boost converter chip (plus the other side of the board underneath because it also gets hot) because the converter chip itself gets pretty warm when run at more than 1A
How would I heatsink both top and bottom? top of chip with heatsink thermal-glued on
and another slightly larger heatsink on the bottomside of the board underneath the chip (is there a thermal glue that isn't electrically conductive?)
I modified a 1A normal and 3A max boost converter that boosts from 2.8v to 30v input
up to 48v
I swapped out the inductor for a toroidal one with thicker wire
And now it happily outputs over 5 and a half amps
boosts a 6v AGM SLA battery up to 12v to run a small 400W power inverter (to run a small load like a phone charger. not running a washing machine or anything like that from it!)
it spiked at a max of 6A and didn't cut off or go into protection mode
so it seems to absolutely love the new inductor i soldered onto it
the original inductor was 470uH
I hand re-wound a copper wire into the toroid and at 1A to 3A the inductor barely gets warm
whereas before it would get SEARING HOT at only 1A!
And I know boosting a 6v 5AH AGM SLA up to 12v is pointless
but I have two 6v SLA AGM 5AH batteries. and a 12v SLA AGM 5AH battery
I was just testing its capabilities
it seems it works great for boosting the super capacitor up to run my 250W class D audio amplifier (only running at 1-6 watts max because i have tiny speakers)
and it lasts a good long time. about 10-15 minutes with 5-10 minutes of continuous use at medium-high volume maybe more if I only boost it up to 4.5v
I do have to charge the super cap up to at least 2.8v to 3v to get it to run the boost converter. but the super capacitor doesnt seem to mind
I need to heatsink the boost converter chip (plus the other side of the board underneath because it also gets hot) because the converter chip itself gets pretty warm when run at more than 1A
How would I heatsink both top and bottom? top of chip with heatsink thermal-glued on
and another slightly larger heatsink on the bottomside of the board underneath the chip (is there a thermal glue that isn't electrically conductive?)
Screwdriver now a heat treated poorly screwed driver.
No, the solder has increased the cross sectional area of the device lead, but the Copper thermal conductivity has more to do with temp. rise in the steel.
No, quick answer is:
If copper is heated to cherry red and cooled [fast or slow] this heat treatment process is called annealing - softens it.
Copper is hardened by working it by bending, hammering, rolling, drawing.
You have 'hard drawn' copper resulting from the manufacturing process that makes wire strands [from large to small] after being drawn through [pulled] progressively smaller dies. It has to be annealed during drawing down due to hardening if small diameter is needed.
Larger single core single insulated Industrial power cable is often 'compact stranded hard drawn' form and not easy to hand bend around corners - very rigid despite being multi stranded.... as opposed to soft flexible cable that may have many fine strands in an annealed state [of same cross sectional area].
The screwedriver is made from steel and was heat treated to harden [heat to red and quench rapidly] and then again heated to far lower temp to 'temper' - retain hardness but remove a degree of brittleness. This 'temper temp. is roughly done by indication of a straw brown colour on a polished section of the material [tool steel has this colour / temp characteristic as does titanium]
Heating, as you have done, has removed the hardness characteristic [all about crystalline structure of the alloy] and it is well and truly screwed... soft as poo.
Might be good for poking holes in a PCB board, or picking dust bunnies out of a heatsink.
Happens with drill bits too.
If you incorrectly sharpen drill bits on a wheel they goes through the same colour change indication.... can happen by incorrect cutting speed and use of blunt bits too.
If it's gone 'blue' it's stuffed and needs careful grinding beyond this 'blue' area to be of any future use as a cutting tool.
Anyhow, bit OT no doubt.
As you were.
Well whatever material its made of it's still hard enough to screw a potentiometer so it works good enough for me.
Cant be bent with fingers yet unless you want to hurt yourself also the sheathing that holds the tip is extremely hard and feels it would break before it'd bend. (but takes solder well for some reason?) I wonder what its made of.. Can't be aluminum. could it? I used one with the screwdriver tip missing out of it as a soldering iron tip.. Still hasn't degraded to this day. and still takes solder great. even better than an actual soldering iron tip. Plus it has a small hole in the end where the tip was to hold solder. I wonder why all my actual soldering tips degraded within minutes of use even after tinning the fudge out of them. yet this mysterious material doesnt degrade no matter how bad I treat it.
The tip itself was safe from the heat so the tip itself didn't heat up probably protecting it.
The metal its made of is very dark in color and still dark in color even after glowing to bright yellow/orange
Maybe its not just plain regular steel but some alloy?
it feels if you were to bend it then bend it back it would snap.
Cant be bent with fingers yet unless you want to hurt yourself also the sheathing that holds the tip is extremely hard and feels it would break before it'd bend. (but takes solder well for some reason?) I wonder what its made of.. Can't be aluminum. could it? I used one with the screwdriver tip missing out of it as a soldering iron tip.. Still hasn't degraded to this day. and still takes solder great. even better than an actual soldering iron tip. Plus it has a small hole in the end where the tip was to hold solder. I wonder why all my actual soldering tips degraded within minutes of use even after tinning the fudge out of them. yet this mysterious material doesnt degrade no matter how bad I treat it.
The tip itself was safe from the heat so the tip itself didn't heat up probably protecting it.
The metal its made of is very dark in color and still dark in color even after glowing to bright yellow/orange
Maybe its not just plain regular steel but some alloy?
it feels if you were to bend it then bend it back it would snap.
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