I've got some questions about voltage regulators for an EE. I'd like to throw some ideas off of somebody on AIM or via PM. Let me know if you're an EE or EE student.
EEs step in.
- Thread starter TitanDiddly
- Start date
I am an EE student. Analog is not my favorate thing, but a voltage regulator shouldn't be too crazy.
I'm not an EE, but I have relevant experience with said components. I install/decommision and troubleshoot radar systems for the AF and I reguliarily go into component level. Just say what's on your mind.
OK, this was a shameless attempt to get more of a response than in HT.
I have an IBM Thinkpad 600, and the battery doesn't last very long. I'd like to use it during a upcoming trip on a plane, totally about 7 hours flight time. The seats I am booked in do not have AC power. I was thinking of making a simple circuit to take 18v from three 6v gel cells and turn it into stable 16v power for my laptop. My laptop adapter is rated for 3.36a, so whatever kind of adapter I make has to be able to source as least that much as a peak value. Does anyone know how feasable this is? I'm not exactly sure how many amps it pulls during normal operation. I'm going to guess 2A as a nice round value. Assuming, say, 85% efficeiently on my voltage converter(I confess. I have no idea what the proper term is), and 7 hours total operation, I'm going to need 14AH for the trip. That's possible to do for carry-on, no?
Also, I know the laptop is expecting very clean power. Can this be accomplished with just a simple array of a few voltage regulators and some big capacitors? I've made some very simple voltage regulators for RC equipment that just takes a higher voltage (12v) and makes clean 5v with it. That's a fairly low amperage situation, though. Is this possible for a fairly novice engineer-to-be? Is it feasable at all? Even if not for carry-on luggage, let's say I want to do it for long car trips and my cigarette lighter plug is broken, or whatever.
One big problem I can think of is voltage drop in the batteries as they drain. I'm going to need either a very low dropout regulator, or use 24v of batteries.
I have an IBM Thinkpad 600, and the battery doesn't last very long. I'd like to use it during a upcoming trip on a plane, totally about 7 hours flight time. The seats I am booked in do not have AC power. I was thinking of making a simple circuit to take 18v from three 6v gel cells and turn it into stable 16v power for my laptop. My laptop adapter is rated for 3.36a, so whatever kind of adapter I make has to be able to source as least that much as a peak value. Does anyone know how feasable this is? I'm not exactly sure how many amps it pulls during normal operation. I'm going to guess 2A as a nice round value. Assuming, say, 85% efficeiently on my voltage converter(I confess. I have no idea what the proper term is), and 7 hours total operation, I'm going to need 14AH for the trip. That's possible to do for carry-on, no?
Also, I know the laptop is expecting very clean power. Can this be accomplished with just a simple array of a few voltage regulators and some big capacitors? I've made some very simple voltage regulators for RC equipment that just takes a higher voltage (12v) and makes clean 5v with it. That's a fairly low amperage situation, though. Is this possible for a fairly novice engineer-to-be? Is it feasable at all? Even if not for carry-on luggage, let's say I want to do it for long car trips and my cigarette lighter plug is broken, or whatever.
One big problem I can think of is voltage drop in the batteries as they drain. I'm going to need either a very low dropout regulator, or use 24v of batteries.
I'm looking at this thing, it sounds useful:
http://www.national.com/pf/LM/LM3485.html
Note sure if I can actually get one/some though.
http://www.national.com/pf/LM/LM3485.html
Note sure if I can actually get one/some though.
First of all I have no clue as to how you would find and implement fuel cells, I'm not very familiar with the technology. I do know that it can be bulky, and mass may also be a concern. Everything you're talking about here is going to pile on the weight, but as long as you're willing to lug it around I suppose it's irrelevant.
If it were me I'd try design the circuit to interface w/ the laptops AC power source since it already has a regulator integrated to smooth out crappy line power. The designer built the laptop and it?s adapter with relatively poor power quality in mind so using it will make life easier for you. That being said, you're going to need to design a rectifier (converts from AC to DC or vice versa) to convert the output from your fuel cell or whatever since it's going to be DC. It can be as simple as a tank circuit to get your 60 Hz; you just have to select your cap and inductor to have characteristics to discharge into each other at that rate. There are many other, more sophisticated and cleaner options available; the tank circuit is just the most basic and most easily implemented. However, it will also depend on your source power as that can affect the rate at which your caps charge. You would also want to put your own regulator in series with your rectifier though, just to make sure it will provide clean enough AC for your laptops adapter.
So now you need to think about how you're going to house these components, and since you're not a robot you're likely going to be working with relative bulkiness. Durability is important, you don't want your rectifier bouncing around, breaking joints and shorting sh1t out so you'd want to think of a way to affix it to either the fuel cell or the laptop (not necessarily permanently.)
I know this all sounds like fun but I for one would not trust my $1k investment to my radio shack kit, especially not in a demanding situation like traveling. Have you considered purchasing an additional battery(ies)?
EDITED FOR SPELLING AND CLARITY
If you're worried about the voltage dropping below 16v, Airline sockets are 15v, and if there is an airline adapter available for your machine, it will probably run just fine from a ~15v source as well (batteries might not charge, or might charge slower).
You probably can just use something like this
http://www.national.com/ds/LM/LM2576.pdf
You probably can just use something like this
http://www.national.com/ds/LM/LM2576.pdf
You can buy most parts from digikey (or other supply houses)
http://www.digikey.com/scripts/dksearch...l?Detail?Ref=310598&Row=335366&Site=US
I am not sure if that link will work, but you can find many different types of voltage regulators using their search
http://www.digikey.com/scripts/dksearch...iteria?Ref=310305&Site=US&Cat=31786130
If this fails, just type in voltage regulator and then filter the results based on your voltage and current parameters. You'll just need to get the right additional components, board and solder away then try it with a DC power supply.
If you look at the bottom of the datasheets, there are a bunch of sample applications you can adapt to your own use. It also tells you what compoents you need to use to achive your desired voltage/ripple.
http://www.digikey.com/scripts/dksearch...l?Detail?Ref=310598&Row=335366&Site=US
I am not sure if that link will work, but you can find many different types of voltage regulators using their search
http://www.digikey.com/scripts/dksearch...iteria?Ref=310305&Site=US&Cat=31786130
If this fails, just type in voltage regulator and then filter the results based on your voltage and current parameters. You'll just need to get the right additional components, board and solder away then try it with a DC power supply.
If you look at the bottom of the datasheets, there are a bunch of sample applications you can adapt to your own use. It also tells you what compoents you need to use to achive your desired voltage/ripple.
a switching regulator like what you've chosen sounds good. as for battery selection... i don't know what relatively inexpensive solution could run a laptop for 7 hours. lead acid gel maybe but it sounds heavy...
but like jjzelinski said, i wouldn't trust something as expensive as a laptop to a power supply built by somebody inexperienced
but like jjzelinski said, i wouldn't trust something as expensive as a laptop to a power supply built by somebody inexperienced
Besides all the EE stuff, you'll also more then likely have to figure out a way to get the heat away from your circuit.
Unless you are really looking for a project (or a way to void your warranty) and easier solution may be an off the shelf inverter and your existing power supply.
Unless you are really looking for a project (or a way to void your warranty) and easier solution may be an off the shelf inverter and your existing power supply.
Originally posted by: helpme
Sounds like a car battery
Gel cell is good stuff, much denser charge to it than wet cells. As in less battery equals more power and more amp hours.
Also, this just occured to me, GOOD LUCK ON GETTING FUEL CELLS THROUGH SECURITY
Just thought I would shout that out to make sure everyone is on the same page, TSA might not care for things of such nature.Originally posted by: jjzelinski
First of all I have no clue as to how you would find and implement fuel cells, I'm not very familiar with the technology. I do know that it can be bulky, and mass may also be a concern. Everything you're talking about here is going to pile on the weight, but as long as you're willing to lug it around I suppose it's irrelevant.
If it were me I'd try design the circuit to interface w/ the laptops AC power source since it already has a regulator integrated to smooth out crappy line power. The designer built the laptop and it?s adapter with relatively poor power quality in mind so using it will make life easier for you. That being said, you're going to need to design a rectifier (converts from AC to DC or vice versa) to convert the output from your fuel cell or whatever since it's going to be DC. It can be as simple as a tank circuit to get your 60 Hz; you just have to select your cap and inductor to have characteristics to discharge into each other at that rate. There are many other, more sophisticated and cleaner options available; the tank circuit is just the most basic and most easily implemented. However, it will also depend on your source power as that can affect the rate at which your caps charge. You would also want to put your own regulator in series with your rectifier though, just to make sure it will provide clean enough AC for your laptops adapter.
So now you need to think about how you're going to house these components, and since you're not a robot you're likely going to be working with relative bulkiness. Durability is important, you don't want your rectifier bouncing around, breaking joints and shorting sh1t out so you'd want to think of a way to affix it to either the fuel cell or the laptop (not necessarily permanently.)
I know this all sounds like fun but I for one would not trust my $1k investment to my radio shack kit, especially not in a demanding situation like traveling. Have you considered purchasing an additional battery(ies)?
EDITED FOR SPELLING AND CLARITY
Fuel cells... that's like, prototype in labs and stuff. I'm just talking about power-dense lead acid batteries.
Originally posted by: dighn
a swithichng regular like what you've chosen sounds good. as for battery selection... i don't know what relatively inexpensive solution could run a laptop for 7 hours. lead acid gel maybe but it sounds heavy...
but like jjzelinski said, i wouldn't trust something as expensive as a laptop to a power supply built by somebody inexperienced
Conveniently, I already have some 16AH gel-cell batteries that I'd like to use, and are within carry-on size limits.
The laptop I built myself, and I have 4 more junk motherboards ready to toss into it should this one die. It's cheap, and I'm willing to test.
Originally posted by: PhasmatisNox
Originally posted by: jjzelinski
First of all I have no clue as to how you would find and implement fuel cells, I'm not very familiar with the technology. I do know that it can be bulky, and mass may also be a concern. Everything you're talking about here is going to pile on the weight, but as long as you're willing to lug it around I suppose it's irrelevant.
If it were me I'd try design the circuit to interface w/ the laptops AC power source since it already has a regulator integrated to smooth out crappy line power. The designer built the laptop and it?s adapter with relatively poor power quality in mind so using it will make life easier for you. That being said, you're going to need to design a rectifier (converts from AC to DC or vice versa) to convert the output from your fuel cell or whatever since it's going to be DC. It can be as simple as a tank circuit to get your 60 Hz; you just have to select your cap and inductor to have characteristics to discharge into each other at that rate. There are many other, more sophisticated and cleaner options available; the tank circuit is just the most basic and most easily implemented. However, it will also depend on your source power as that can affect the rate at which your caps charge. You would also want to put your own regulator in series with your rectifier though, just to make sure it will provide clean enough AC for your laptops adapter.
So now you need to think about how you're going to house these components, and since you're not a robot you're likely going to be working with relative bulkiness. Durability is important, you don't want your rectifier bouncing around, breaking joints and shorting sh1t out so you'd want to think of a way to affix it to either the fuel cell or the laptop (not necessarily permanently.)
I know this all sounds like fun but I for one would not trust my $1k investment to my radio shack kit, especially not in a demanding situation like traveling. Have you considered purchasing an additional battery(ies)?
EDITED FOR SPELLING AND CLARITY
Fuel cells... that's like, prototype in labs and stuff. I'm just talking about power-dense lead acid batteries.
Originally posted by: dighn
a swithichng regular like what you've chosen sounds good. as for battery selection... i don't know what relatively inexpensive solution could run a laptop for 7 hours. lead acid gel maybe but it sounds heavy...
but like jjzelinski said, i wouldn't trust something as expensive as a laptop to a power supply built by somebody inexperienced
Conveniently, I already have some 16AH gel-cell batteries that I'd like to use, and are within carry-on size limits.
The laptop I built myself, and I have 4 more junk motherboards ready to toss into it should this one die. It's cheap, and I'm willing to test.
It sounds like a fun project but whether it be a fuel cell or a full size gel-cell 16ah battery it may e better suited to a long bus ride
Again, security is something you'd want to look into here. If they have you check your gel-cell in that wouldn't be very useful, would it http://www.zbattery.com/zbattery/ub13-6.html
Sealed lead acid = Gel Cell?
3 batteries @ 5 pounds each. That's pretty heavy to be lugging around, that's like a 20 pound laptop bag.
Sealed lead acid = Gel Cell?
3 batteries @ 5 pounds each. That's pretty heavy to be lugging around, that's like a 20 pound laptop bag.
Originally posted by: jjzelinski
Originally posted by: PhasmatisNox
Originally posted by: jjzelinski
First of all I have no clue as to how you would find and implement fuel cells, I'm not very familiar with the technology. I do know that it can be bulky, and mass may also be a concern. Everything you're talking about here is going to pile on the weight, but as long as you're willing to lug it around I suppose it's irrelevant.
If it were me I'd try design the circuit to interface w/ the laptops AC power source since it already has a regulator integrated to smooth out crappy line power. The designer built the laptop and it?s adapter with relatively poor power quality in mind so using it will make life easier for you. That being said, you're going to need to design a rectifier (converts from AC to DC or vice versa) to convert the output from your fuel cell or whatever since it's going to be DC. It can be as simple as a tank circuit to get your 60 Hz; you just have to select your cap and inductor to have characteristics to discharge into each other at that rate. There are many other, more sophisticated and cleaner options available; the tank circuit is just the most basic and most easily implemented. However, it will also depend on your source power as that can affect the rate at which your caps charge. You would also want to put your own regulator in series with your rectifier though, just to make sure it will provide clean enough AC for your laptops adapter.
So now you need to think about how you're going to house these components, and since you're not a robot you're likely going to be working with relative bulkiness. Durability is important, you don't want your rectifier bouncing around, breaking joints and shorting sh1t out so you'd want to think of a way to affix it to either the fuel cell or the laptop (not necessarily permanently.)
I know this all sounds like fun but I for one would not trust my $1k investment to my radio shack kit, especially not in a demanding situation like traveling. Have you considered purchasing an additional battery(ies)?
EDITED FOR SPELLING AND CLARITY
Fuel cells... that's like, prototype in labs and stuff. I'm just talking about power-dense lead acid batteries.
Originally posted by: dighn
a swithichng regular like what you've chosen sounds good. as for battery selection... i don't know what relatively inexpensive solution could run a laptop for 7 hours. lead acid gel maybe but it sounds heavy...
but like jjzelinski said, i wouldn't trust something as expensive as a laptop to a power supply built by somebody inexperienced
Conveniently, I already have some 16AH gel-cell batteries that I'd like to use, and are within carry-on size limits.
The laptop I built myself, and I have 4 more junk motherboards ready to toss into it should this one die. It's cheap, and I'm willing to test.
It sounds like a fun project but whether it be a fuel cell or a full size gel-cell 16ah battery it may e better suited to a long bus ride
True. I'll call the airline.
Just called the airline, they were helpful. They couldn't find anything specifically about it, but they seemed to think that as long as it's a sealed battery, it should be fine. I'm going to try and make everything look very professional, not like I threw it together myself... even though I did. I still need to find the right voltage reg though. Is this something that's going to be in a TO-220 package or similar? TO-220 seems awfully small for the amount of current I'd need, but I'm seeing it on some spec sheets. Do somr TO-220 FETs actually run 3A?
FETs have generally low "ON" resistance so they can take large current
looking at the specs though, it seems ripple could be a problem. if you had access to an oscilloscope to verify the ripple it would be great. also might have to watch the EMI on an airplane
looking at the specs though, it seems ripple could be a problem. if you had access to an oscilloscope to verify the ripple it would be great. also might have to watch the EMI on an airplane
GOod thought on the EMI, but he won't even be taking it out until after they're out of the IFR region (instrument flight rule). That being said, EMI shouldn't be a big deal.
As far as ripple is concerned, I still highly suggest you mae use of your laptops specifically calibrated regulators. Make use of your AC adapter, it will help prevent you from completely trashing your laptop and it should make the design much easier.
I'd very much like to avoid going from 12VDC>120AAC>16VDC. It's just so ineffiencient. I think that if I can get clean 16v power, the laptop will eat it. I don't have access to an o-scope, I don't think- I'm friends with a local high school tech ed teacher who has access to scopes, but neither I nor him know how to use them.
I still think you can make a simple regulator to fit your needs with one of the devices I suggested such as:
http://www.national.com/ds/LM/LM2576.pdf
You shouldn't need too many components, A diode, a couple caps and a couple resistors. Just check out the design examples they include.
National also has a product chooser that you can enter in requirements into, and it will spit out the devices that fit the bill.
http://www.national.com/ds/LM/LM2576.pdf
You shouldn't need too many components, A diode, a couple caps and a couple resistors. Just check out the design examples they include.
National also has a product chooser that you can enter in requirements into, and it will spit out the devices that fit the bill.
Woah!!
This thread is full of useless advice. The guy is not going to use fuel cells people. He's using sealed lead batteries, also called gel cells.
Here's what you need for the simplest solution:
LM350 (take a 3A version) - linear adjustable voltage regulator
2 resistors.
16V out from 18V in means a drop of 2V over the regulator.
At 2A load this comes out to 2x2W = 4W heat, which means you need a heatsink.
Bottom of page 5 shows how to make one.
This thread is full of useless advice. The guy is not going to use fuel cells people. He's using sealed lead batteries, also called gel cells.
Here's what you need for the simplest solution:
LM350 (take a 3A version) - linear adjustable voltage regulator
2 resistors.
16V out from 18V in means a drop of 2V over the regulator.
At 2A load this comes out to 2x2W = 4W heat, which means you need a heatsink.
Bottom of page 5 shows how to make one.
When I made this thread I was thinking 18v, but now it's looking more like 24v. I want to put the whole thing in an aluminum enclosure, and use that as heatsink. I think a nice Al enclosure that looks professional would put the airport security inspectors at ease a bit, too.
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