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Author Topic: How do I turn 24v to 5volt  (Read 2647 times)

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Offline offenceroboticsTopic starter

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How do I turn 24v to 5volt
« on: January 08, 2011, 12:10:37 AM »
Ok so my robot runs on a 24 volt battery I need to make a regulated 5v 30 amp power . I've done this before with a LM317 Voltage Regulator but not for 30 amp how would I do this?

Offline knossos

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Re: How do I turn 24v to 5volt
« Reply #1 on: January 08, 2011, 04:38:27 AM »
What do you need 30 amps @ 5 volts for?  If its for multiple low amperage items @ 5 volts I would consider using multiple circuits to reduce the amperage per circuit.  Of course, I would use switching regulators to improve efficiency.  If its for a couple of high amp items, I would reevaluate my need for a 24v power source or possibly have dual power sources.  Also does the full 30 amps need to be regulated?
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Offline waltr

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Re: How do I turn 24v to 5volt
« Reply #2 on: January 08, 2011, 10:04:06 AM »
If you really need 30A and really want to use an LM317 look at the application info on the data sheet for using a pass transistor (or 2 or 8). Just don't forget the Heatsinks.

Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #3 on: January 08, 2011, 11:56:45 AM »
well it to run my desktop computer that in side my robot off the 24 volt battery the power supply that came with the desktop put out 5v 30 amp 12v 12 amp and 3.3 volt 14 amp.

Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #4 on: January 08, 2011, 05:37:46 PM »
How would I do this? do you have any examples drawings ? what's a "pass transistor" ? I look at the data sheet and can't find this.
If you really need 30A and really want to use an LM317 look at the application info on the data sheet for using a pass transistor (or 2 or 8). Just don't forget the Heatsinks.

Offline Soeren

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Re: How do I turn 24v to 5volt
« Reply #5 on: January 08, 2011, 06:17:06 PM »
Hi,

How would I do this? do you have any examples drawings ? what's a "pass transistor" ? I look at the data sheet and can't find this.
If you really need 30A and really want to use an LM317 look at the application info on the data sheet for using a pass transistor (or 2 or 8). Just don't forget the Heatsinks.
First of all. The fact that your supply is able to put out 30A doesn't necessarily mean that your PC will need that much, especially if it's only lightly loaded.

Second: You don't wanna make this as a linear supply. Dropping 19V at 30A is 570W lost as heat to get 150W of usable power (Total drain from your 24V battery would be 720W!).
A switcher is the only sensible way.

If you get a motherboard made especially for battery supply, power demands are much lower.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline billhowl

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Re: How do I turn 24v to 5volt
« Reply #6 on: January 08, 2011, 10:59:24 PM »

http://www.eleccircuit.com/high-current-regulated-supply-by-lm317/
This is the "pass transistor" that waltr talking about

But I don't think you can use LM317 to make your own power supply for your robot, you can get one of this


Quote
Features
- NEW! Smart Car PC Power Supply- 140 watts output
- Ideal car Power supply for operating Core 2 duo, Celeron, AMD systems
- ATX, 6-32V wide input range
- Intelligent shutdown controller
- ON/OFF motherboard control
- Survives vehicle engine cranks
- Battery deep discharge prevention
- High efficiency, 140 watts output
- "Anti-Thump" Amplifier remote control - 15A automotive fuse (mini-blade)
- VIA, Core 2 duo and AMD CPU support
- manufactured by mini-box.com
- ROHS compliant version

http://www.mini-box.com/M2-ATX-HV-140w-Intelligent-Automotive-DC-DC-Power-Supply_2?sc=8&category=13
http://resources.mini-box.com/online/PWR-M2-ATX-HV/PWR-M2-ATX-HV-manual.pdf

Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #7 on: January 09, 2011, 01:20:18 AM »
what a "switcher"?
Hi,

How would I do this? do you have any examples drawings ? what's a "pass transistor" ? I look at the data sheet and can't find this.
If you really need 30A and really want to use an LM317 look at the application info on the data sheet for using a pass transistor (or 2 or 8). Just don't forget the Heatsinks.
First of all. The fact that your supply is able to put out 30A doesn't necessarily mean that your PC will need that much, especially if it's only lightly loaded.

Second: You don't wanna make this as a linear supply. Dropping 19V at 30A is 570W lost as heat to get 150W of usable power (Total drain from your 24V battery would be 720W!).
A switcher is the only sensible way.

If you get a motherboard made especially for battery supply, power demands are much lower.


Offline hopslink

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Re: How do I turn 24v to 5volt
« Reply #8 on: January 09, 2011, 03:35:29 AM »
switcher = switch-mode.

Your desktop motherboard will typically need 12V, 5V, and 3.3V regulated power, not just 5V. A DC-DC PSU like billhowls suggestions above is a switch-mode power supply providing all the required voltages, and is plug and play. Either this or Soerens DC motherboard is likely to be the best solution - depending on your intended use and budget etc.

Offline TrickyNekro

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Re: How do I turn 24v to 5volt
« Reply #9 on: January 09, 2011, 12:31:41 PM »
Switcher actually means, that's using a oscillation to provide the needed energy at the needed voltage... :-p

In a lineal regulator, the power would be eaten up in a resistor... In a switching regulator, power is stored in capacitors via an oscillation and given to the target... minimizing the loses this way...
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

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Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #10 on: January 09, 2011, 12:50:45 PM »
so I'm going to with "billhowl" idea and buy a dc dc computer power supply I found some on ebay the are 250 watts and cost about $70 shipped from china. But I really want to understand how to make a "Switcher voltage regulated power" does anyone have a simple schematic that I can try out on my solderless breadboard?

Offline Soeren

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Re: How do I turn 24v to 5volt
« Reply #11 on: January 10, 2011, 12:04:50 PM »
Hi,

But I really want to understand how to make a "Switcher voltage regulated power" does anyone have a simple schematic that I can try out on my solderless breadboard?
A 250W switcher (SMPSU, Switch Mode Power Supply Unit) is not for the uninitiated and certainly not something you build on a solderless board.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Admin

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Re: How do I turn 24v to 5volt
« Reply #12 on: January 11, 2011, 02:19:47 PM »
well it to run my desktop computer that in side my robot off the 24 volt battery the power supply that came with the desktop put out 5v 30 amp 12v 12 amp and 3.3 volt 14 amp.
backing up here for a bit . . .

You want to put your PC inside a robot? :o

Keep in mind that the hard drive might get damaged if your bot crashes into walls . . . not to mention all the added weight! And then you got that big heavy 24V lead acid battery. More weight means bigger and more expensive motors.

Why not get a cheap laptop (craptop) off of ebay? It'll probably cost you the same as everything you need to support a PC on your bot.

Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #13 on: January 11, 2011, 07:59:38 PM »
No I'm going to buying a 250W switcher (SMPSU, Switch Mode Power Supply Unit) on ebay , but I want to build a simple one on my solderless board just to understand it a for fun.
Hi,

But I really want to understand how to make a "Switcher voltage regulated power" does anyone have a simple schematic that I can try out on my solderless breadboard?
A 250W switcher (SMPSU, Switch Mode Power Supply Unit) is not for the uninitiated and certainly not something you build on a solderless board.


Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #14 on: January 11, 2011, 08:08:44 PM »
yes it strip down desktop computer , the robot is life size and has two 250 watt 24 volt motors out of a scooter so it allready go to have the battery on board, I also need the desktop for the pci's slots it has.
well it to run my desktop computer that in side my robot off the 24 volt battery the power supply that came with the desktop put out 5v 30 amp 12v 12 amp and 3.3 volt 14 amp.
backing up here for a bit . . .

You want to put your PC inside a robot? :o

Keep in mind that the hard drive might get damaged if your bot crashes into walls . . . not to mention all the added weight! And then you got that big heavy 24V lead acid battery. More weight means bigger and more expensive motors.

Why not get a cheap laptop (craptop) off of ebay? It'll probably cost you the same as everything you need to support a PC on your bot.

Offline waltr

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Re: How do I turn 24v to 5volt
« Reply #15 on: January 11, 2011, 09:07:17 PM »
No I'm going to buying a 250W switcher (SMPSU, Switch Mode Power Supply Unit) on ebay , but I want to build a simple one on my solderless board just to understand it a for fun.
Hi,

But I really want to understand how to make a "Switcher voltage regulated power" does anyone have a simple schematic that I can try out on my solderless breadboard?

A 250W switcher (SMPSU, Switch Mode Power Supply Unit) is not for the uninitiated and certainly not something you build on a solderless board.




You can make a low frequency, low current DC-DC switcher on a solderless board to learn about the basics.
A perf-board would be a bit better if you want to try higher currents but just don't expect too much.

Google and read:
dc-dc converter
Boost converter
Buck converter
555 dc-dc converter
7660 charge pump voltage converter
Then look at data sheets and app notes from:
Linear Tech
National Semiconductor
Maxim-  http://www.maxim-ic.com/
Analog Devices

That should keep you busy.

Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #16 on: January 11, 2011, 09:20:06 PM »
found one here http://www.eleccircuit.com/12v-to-18v-step-up-dc-converter-by-ic-555/
thank you
No I'm going to buying a 250W switcher (SMPSU, Switch Mode Power Supply Unit) on ebay , but I want to build a simple one on my solderless board just to understand it a for fun.
Hi,

But I really want to understand how to make a "Switcher voltage regulated power" does anyone have a simple schematic that I can try out on my solderless breadboard?

A 250W switcher (SMPSU, Switch Mode Power Supply Unit) is not for the uninitiated and certainly not something you build on a solderless board.




You can make a low frequency, low current DC-DC switcher on a solderless board to learn about the basics.
A perf-board would be a bit better if you want to try higher currents but just don't expect too much.

Google and read:
dc-dc converter
Boost converter
Buck converter
555 dc-dc converter
7660 charge pump voltage converter
Then look at data sheets and app notes from:
Linear Tech
National Semiconductor
Maxim-  http://www.maxim-ic.com/
Analog Devices

That should keep you busy.

Offline blackbeard

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Re: How do I turn 24v to 5volt
« Reply #17 on: January 11, 2011, 09:42:14 PM »
well it to run my desktop computer that in side my robot off the 24 volt battery the power supply that came with the desktop put out 5v 30 amp 12v 12 amp and 3.3 volt 14 amp.

backing up here for a bit . . .

You want to put your PC inside a robot? :o

Keep in mind that the hard drive might get damaged if your bot crashes into walls . . . not to mention all the added weight! And then you got that big heavy 24V lead acid battery. More weight means bigger and more expensive motors.

Why not get a cheap laptop (craptop) off of ebay? It'll probably cost you the same as everything you need to support a PC on your bot.


for the hard drive thing you can go with an 8gb ssd which i've seen for $40. i like the idea of using an old desktop computer because you can add pci cards that can actually make it fairly useful. also laptops are not THAT cheep

http://cgi.ebay.com/Kingspec-1-8-Inch-8GB-SATA-II-MLC-SSD-Solid-State-Drive-/120667136468?pt=AU_Laptop_Accessories&hash=item1c185261d4

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Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #18 on: January 11, 2011, 10:02:54 PM »
Thank you soooo much you solved my hard drive problem

well it to run my desktop computer that in side my robot off the 24 volt battery the power supply that came with the desktop put out 5v 30 amp 12v 12 amp and 3.3 volt 14 amp.

backing up here for a bit . . .

You want to put your PC inside a robot? :o

Keep in mind that the hard drive might get damaged if your bot crashes into walls . . . not to mention all the added weight! And then you got that big heavy 24V lead acid battery. More weight means bigger and more expensive motors.

Why not get a cheap laptop (craptop) off of ebay? It'll probably cost you the same as everything you need to support a PC on your bot.


for the hard drive thing you can go with an 8gb ssd which i've seen for $40. i like the idea of using an old desktop computer because you can add pci cards that can actually make it fairly useful. also laptops are not THAT cheep

http://cgi.ebay.com/Kingspec-1-8-Inch-8GB-SATA-II-MLC-SSD-Solid-State-Drive-/120667136468?pt=AU_Laptop_Accessories&hash=item1c185261d4



Offline Soeren

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Re: How do I turn 24v to 5volt
« Reply #19 on: January 12, 2011, 09:06:08 PM »
Hi,

for the hard drive thing you can go with an 8gb ssd which i've seen for $40. i like the idea of using an old desktop computer because you can add pci cards that can actually make it fairly useful. also laptops are not THAT cheep

http://cgi.ebay.com/Kingspec-1-8-Inch-8GB-SATA-II-MLC-SSD-Solid-State-Drive-/120667136468?pt=AU_Laptop_Accessories&hash=item1c185261d4

8GB SSD for AU$31.59?
Sounds way too cheap!
Even though the seller seems like a commercial seller, he's got only 10 sales (as of writing), sort of like the one my GF bought a wrist watch from (defect at arrival, sent back for a replacement on agreement with seller - suddenly his account was removed and she never heard more about it - would have been cheaper to just toss the watch). So I'd have to say Caveat Emptor.

Several places (like Brando) sells IDE interfaces that accepts CF cards etc. and looks like a regular HD to the system.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline offenceroboticsTopic starter

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Re: How do I turn 24v to 5volt
« Reply #20 on: January 12, 2011, 09:28:14 PM »
is this what your talking about? http://www.compuplus.com/Drives-and-storage/Startechcom-Compact-Flash-to-IDE-1015543.html
Hi,

for the hard drive thing you can go with an 8gb ssd which i've seen for $40. i like the idea of using an old desktop computer because you can add pci cards that can actually make it fairly useful. also laptops are not THAT cheep

http://cgi.ebay.com/Kingspec-1-8-Inch-8GB-SATA-II-MLC-SSD-Solid-State-Drive-/120667136468?pt=AU_Laptop_Accessories&hash=item1c185261d4

8GB SSD for AU$31.59?
Sounds way too cheap!
Even though the seller seems like a commercial seller, he's got only 10 sales (as of writing), sort of like the one my GF bought a wrist watch from (defect at arrival, sent back for a replacement on agreement with seller - suddenly his account was removed and she never heard more about it - would have been cheaper to just toss the watch). So I'd have to say Caveat Emptor.

Several places (like Brando) sells IDE interfaces that accepts CF cards etc. and looks like a regular HD to the system.


 


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