USB Syncroized 5V@8A power supply POL. Now Taking Orders!!! - Page 2

Beehphy · 08-31-2007, 01:03 PM

The tricky part about putting a regulated 12V output in an automotive enviroment is maintaining a 1.5-2V headroom required for a simple regulator. In order to opperate an LM7812 voltage regulator the input needs to be ~1.5V above the output. In an automotive environment, where you have to design for worse case, I cannot assume that the cars power system will not drop below that voltage.

So... in a auto environment a DC-DC converter is needed to take the unregulated 12V and make it regulated 12V. A DC-DC converter is much more complicated than a linear regulator.

To add this feature to my design would amount to doubling the existing circuitry to accomodate the two regulated outputs. unfortunately there is not enough room to do this in my design.

Update to the project:
towards the beginning of summer I lost interest and went outside to play in the sun

but I'm feeling renewed interest and have some part ordering to do. My prototype suffered a devistating blow durring line regulation testing when a test lead shorted the high power switching node (with high voltage sipkes) to a delicate current sensing pin, the controll chip died

. I have to order almost all the parts again and build another prototype to continue development.

BiG K · 08-31-2007, 04:01 PM

Dude! The railgun is fricken schweet! Upload the pictures on Youtube....it'll save on hosting costs ;-)

I might be interested in the power supply, but not at the moment. I haven't got my car yet or passed my drivers test, but hopefully will do quite soon! woo!

Brycestro · 09-01-2007, 09:45 AM

I think this device could be quite popular once it's fully tried and tested. Keep us updated on progress

Beehphy · 10-24-2007, 04:15 PM

UPDATE!!! 10/23/07

Much work has taken place since my last post.

10A model is dead for now. Unless multiple people start asking for a 10A version it won’t be made. It was proving difficult to create a stable and reliable unit that would fit in the defined space without overheating or raising the price considerably.

I have re-designed the unit and built a 5A model that’s proving to be very capable and tough. I recently tested the 5A model (with pic) and found it to be very efficient (89%) and not suffering the same faults as the 10A model.

I have also determined that 5A should be plenty of power to supply any in-car USB system. Remember that each USB port can supply 0.5A, but most devices use far less. Unless you are using 5 USB powered hard drives at the same time you should be fine.

During testing I cranked the load current to over 6A and let it run for ~30min. After running at that high load I checked the temperature of the power components and found them to be warm, but not hot. This is a good sign for the longevity of the unit.

Electronics break down due to heat. The power components in this design are capable of operating at 125C. The hottest component in the power supply was ~55C.

What can we gather from this information? This design will run safe in any environment. Here’s why; when running in a 27C room, the power components temperature stabilized about 30C above the surrounding environment. The components were releasing heat as fast as they were making it when the components were 30C hotter that the surrounding air.

In the trunk of a car in the hot sun, the trunk might reach 55C (130F), in that case the electronics would again heat up 30C above the surrounding environment. Even if the components raised 35C, the total, 90C is still below the operating temperature of the components. They would still be within a safe operating region.

The other great finding from the test showed great output voltage regulation. At 0A output the voltage was 5.05V, at 5.75A the output voltage was 4.88V. Not very much change for the difference in output current.

Most USB devises will work within 10% of 5V (4.5-5.5V). At 4.88V the output is 2.4% away from the nominal output of 5V, well within spec.

I will spec this design as 5V @ 5A, since a safety margin should be used. If this device is outputting less than 5A it will work in any conditions (except under water!).

Now taking orders
I am proud to offer this product for $80. That price gets you an assembled power supply, with manual.

Once I have 5 confirmed buyers I will make a run of 10.

Speak up to get yours! (soon)

greatwhite · 10-24-2007, 04:40 PM

Umm.......

Not to sound negative or anthing, but why would someone pay 85 bucks for a 5v supply when you could buy an 80w m2-atx for the same price?

Just wondering..........

Beehphy · 10-25-2007, 11:47 PM

Quote: Originally Posted by greatwhite

Umm.......

Not to sound negative or anthing, but why would someone pay 85 bucks for a 5v supply when you could buy an 80w m2-atx for the same price?

Just wondering..........

Because you can't just have a m2-atx flopping around your trunk, hooked up and powering stuff.

there's no chassis to provide protection.
there's no good way to mount the m2 in your trunk.
you need special connectors to connect to it.
it doesn't follow the computer on/off (in a simple manner)

My product has a tough case that allows for easy mounting. simple, yet robust connectors and it has a simple and easy way to power on and off with the computer.

BTW the reason it cost $80 is cause I'm just a guy who likes to make stuff. I'm not a high volume manufacturer, so I cant buy the components as cheaply. if i could afford to buy all the stuff to make 1000 of them it would probably be lots less. the price you'll pay for one of these amounts to parts and paying me minimum wage to assemble it. I'm not even trying to recover the time or money I've invested in designing and testing.

It's not the answer for everyone.

If you need a powerful, reliable, tough 5V supply for your carputer, here it is.

greatwhite · 10-26-2007, 08:48 AM

OK.

I'm not trying to say your unit isn't worth it's price or application. I was just wondering what it's advantages over a dc-dc power supply were.

Good luck with your sales.

sivart321 · 10-30-2007, 11:17 PM

Sounds interesting... im curious what the protocol currently is for when the computer powers the USB bus. Does it do it as soon as the computer begins starting up? and turn off after the computer turns off?

turbocad6 · 10-31-2007, 12:00 AM

from what I've seen, it comes up right away, & drops off at the very end...

2k1Toaster · 10-31-2007, 12:12 AM

Quote: Originally Posted by Beehphy

The USB port on my device is the trigger (enable) for the power supply. the Tx and Rx lines are left floating since there is no comm with the computer. the 5V is a very low current draw (0.1mA) to enable the power supply. the computer doesn't even know it has been pluged in.

Quote: Originally Posted by Beehphy

it doesn't follow the computer on/off (in a simple manner)

I dont understand then. As soon as the motherboard gets power, USB gets power. Right before the computer shuts off, the USB shuts off. This follows the computer exactly. What is the benefit for switching off of the 5v USB when you could just use the 12v/5v already in use?

Beehphy · 10-31-2007, 03:24 PM

Quote: Originally Posted by 2k1Toaster

What is the benefit for switching off of the 5v USB when you could just use the 12v/5v already in use?

The 5V from the computer's pwoer supply could be used. The m2 can supply 8A @ 5V but... there are many other systems in the computer using the 5V source.

bennifits to pulling from the computers psu:
simple. easy. sync'd by default.

drawbacks to pulling from the computers psu:
Style: there's going to be an odd wire sticking out of your computer case, not your friend when goin for a clean install.
System redundancy: in the event of an overload on the 5V rail the psu goes into protect mode and entire computer powers off, possibly causing hardware/software/driver damage. this could easly be caused by the 5v rubbing against something sharp thats grounded.
Noise, a computer psu under high load is electrically noisy, not good for your sound card. and the m1 and m2 are especially noisy.

Using my 5v supply you can avoid all the drawbacks mentioned above and have the benifits too.

BTW: I am twaeking the 5A model to try and achieve 10 like I origionally proposed. I am also designing a budget model. With focus on price cutting. there are several features missing but it will still be highly functional. I think I will still offer the full featured model at the same price.

The missing features are:
No more switched 12V (unregulated 12v output sync'd with PSU)
No more seperate 12V remote enable signal input (could be done by hacking up a usb cable, the enable input at the USB connector is safe for +50V enable signal input)
No red alarm light. (green power good light will go away if protect/failed)
standby current will be higher (wont know value until testing)

Feature still intact:
ATC Fused input
overcurrent/overtemp protection
high efficiency
highly stable/steady output.
power output indicator
USB-B plug for computer sync
screw type terminal block, 4pos (12V in, GND, 2x 5Vout )
~5" x 3.5" x 1.25" Extruded aluminum chassis, painted black
Mounting tabs
Electricaly floating chassis
8-20V input range

Still simple, eligant and powerfull.

let me know what you guys think.

Petter · 11-07-2007, 03:58 PM

Hello Beehphy.

What's the status on your project?
Do you have anything working yet?

I think that I have been trying to accomplish the same as you are working on, only using out of the box parts. If I have understood correctly, it would be possible to solve this with a carnetix power, a 12V relay and some soldering. However there would be some obvious differences; yours in a nice box, output...

Just to be sure that I have understood how to apply your PSU, I have made a simple drawing. Could you confirm if I'm on the track.

Regards
Petter

HiJackZX1 · 11-07-2007, 05:08 PM

Quote: Originally Posted by Beehphy

drawbacks to pulling from the computers psu:
1) Style: there's going to be an odd wire sticking out of your computer case, not your friend when goin for a clean install.
2) System redundancy: in the event of an overload on the 5V rail the psu goes into protect mode and entire computer powers off, possibly causing hardware/software/driver damage. this could easly be caused by the 5v rubbing against something sharp thats grounded.
3) Noise, a computer psu under high load is electrically noisy, not good for your sound card. and the m1 and m2 are especially noisy.

1) I have my PC on my passenger back seat. My car has complicated electronics for the seat so there is no room. I used the 12V rail to power my GPS, cooling fans, and XM adapter. I did not like the power cables with the USB so I simply added a Split Loom which covers all of them... making it nice and clean.

2) Like number 1, use split loom and all will be protected....

3) I agree with you, the M2 is very noisey. So I bought ground loop isolators from InstallEdge.com and the noise is gone with a 3 db gain and no lose of quality...all other isolators seem to muffle the sound.

Not trying to be smart at all, but i am not sold on paying 90, or even 85 dollars. I hope you do come up with a nice price budget model. I have 3 hubs and all are suffering from not having enough power......

Beehphy · 11-08-2007, 12:14 PM

Quote: Originally Posted by Petter

What's the status on your project?

in redesigning the simple/base model i discovered that I seem to have made a simple mathmatical error on the 10A model and will be refitting the circuit board with the correct parts soon. then retesting to see if the fix works.

Quote: Originally Posted by Petter

Do you have anything working yet?

I have the 5A with switched unregulated 12V version working for sure. those are the numbers for it a few post above. the 5A without 12V output is still under development.

Quote: Originally Posted by Petter

Just to be sure that I have understood how to apply your PSU, I have made a simple drawing. Could you confirm if I'm on the track.

you have it right, except for the regulated 12V. the 12V output from my PSU is unregulated. If your LCD screen can handle raw 12V (12-14.6V) from your cars electrical system this will pose no problem.

inh · 11-08-2007, 01:51 PM

$80 for a kit.. This is using SMD components, right? Soldering those has got to be a *****..

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