Sproggy parts problems: alternatives..

**3ntropy** · 05-04-2002, 02:59 AM

Hi ,
Just another guy whos making a sproggy mk2.6 with more questions ..

1. Is there some deep reason that I am too simplistic to decipher for why the inductor in the parts list is 22uh and in the schematics it is 10uh?

2. I could not find a 1800uF cap anywhere. suggestions?? Is using a 2200uf in its place very bad?

3. I can see that the currents from this are not going to be enough even for my mostly integrated MBD system, mainly the 12v , so I am asking : has anyone ACTUALLY used a maxim 642 based 12v rail succesfully? If yes any pointers? will it work when the battery goes below 12v? I need about 2.5 amps total 12v power. How much will this give me?

4. Since the t6 is very problematic to obtain, what are the cons of using max775 (-12v) and max642 (+12) instead ? I dont know this, please be kind.

5. Even with all said and done, the supply will not be enough by itself. So I plan to make a second one and use the 5v and 3.3v rail. It would be really nice if someone could modify the sproggy and make a pcb layout with TWO each of the 3.3v and 5v ICs.

6. I am also having trouble finding the 1N diodes. any suggestions where to get? I know about websites, but hasn't anyone been able to find them off the shelf , local shops, rat-shack etc?

7. Is there such a thing as a mk2.7 sproggy? WHERE?? Is it reliable?

I am so sick of these problems that I am thinking of buying the $30 400w inverter from sams club and forgetting the dc-dc business..
Thanks a lot in advance,
3ntropy

(600mhz celeron, ati all in wonder, 5.6lcd , hdd not yet decided, micro atx mbd with sound/vga/lan ,rf keyboard, 2 fans, budget challenge : do it under $400)

**quijobe** · 05-05-2002, 04:06 PM

1. The 10uh on the schematics is correct.

2. I've been using a 2200uf in place of the 1800uf and it seems to work fine.

4. I had no problem obtaining a T6, you just have to ask nicely.

Dont buy an inverter. Your problems aren't that bad and the DC-DC is well worth the trouble.
quijobe

**3ntropy** · 05-05-2002, 09:45 PM

Thanks quijobe.
I just noticed that in the picture behind the relay where there should be two 1800uf caps , one is actually 2200uf !!

http://sproggy.mp3car.com/psumk25/Stage4lrg.jpg

Could sproggy please clarify?
I understand it cant be too bad using the 2200uf if the instructions also have them. Though knowing the exact reason why that cap is there would help decide how critical its exact value really is. like whether we ought to use a replacement with LESS uF or MORE.

Cheers,
3ntropy

**JesTa784** · 05-13-2002, 11:37 AM

On the topic of alternative parts...

has anyone found replacements for the T6 transformer?

I understand that coiltronics doesn't want to give out both the 68uH 1:1.2:1.2 transformer and the 20uH 1:1 transformer. Has anyone found replacements parts for these either at digikey or mouser or any other suppliers?

Also would it be possible to construct these? I assume just wrapping 1:1 wire ratio is a possibility? And why 68uH for the 1:1.2:1.2 transformer? I assume there is some mathematical reason for this value since the National Semiconductor datasheets suggest 20uH? If someone can explain, that would be great.

I'm going to dig through some more catalogs... one thing that I do notice however is that these aren't listed under transformer at all. Usually they're listed under the inductor section.

Well please keep me updated since I'm very eager to get started on my sproggy =)

**vickumar** · 05-13-2002, 01:26 PM

hmm...

Go to an electronics store... get some ferrite cores.... get the correct guage wire... use a simple formula the store guy might even have to calculate number of turns to make 10/20/40uH or whatever else you want. You can also find that formula on the web... takes into account diameter, length of ferrite core...

**JesTa784** · 05-13-2002, 03:11 PM

yeah actually i've been looking at some websites, except i can't find any really good ones. Do you have any pointers you can give me?

here's two links I found:

http://mp3box.2y.net/ps/
in this one they teach you to make a transformer for 12v, 5v and 3.3v, but i'm not sure what transformer they started with, and how to actually calculate the number of turns i need for that T6.

http://www.skylab.org/~chugga/mpegbox/coil/
This one just tells you to keep on winding

I have no idea when to stop hahaha

so yeah, if anyone can help, PLEASE DO!

**mp3z24** · 05-13-2002, 03:47 PM

try these:

google search!

site 1

site 2

site 3

site 4 (look at bottom)

hope they help

~Mike

**Jimbobarang** · 05-13-2002, 05:42 PM

Hey,

I used the online calculator on this site to calculate the flyback transformer winding details:

http://henry.fbe.fh-darmstadt.de/smp...d_hilfe_e.html

http://henry.fbe.fh-darmstadt.de/smps_e/smps_e.asp

It's pretty complicated if you consider all the factors ie. core mustn't saturate, etc.

Home made transformer works fine, i've got the T6b as well. Used the lie-through-teeth method to get them.

The Sproggy +/-12 V is calculated using the National online Webench program. Give it a go, just stick in the required parameters and it'll show you the schematics that the sproggy was based on.

The 12V PSU is the only section i've had problems with. Bloody thing draws 1.5 A and hums like hell. Prob because i've disarded the PCB and built it on veroboard. I'll sort it out when i've got time.

At the moment i'm on that eternal search for the perfect screen...

8", VGA input, touch screen, blue sky, clear ocean, warm beach, mmm and cocktails ...

Loosing the plot,

J

**JesTa784** · 05-14-2002, 10:42 AM

Looks difficult... I'll take some time to study these though... and I'll definitely give it a try...

How would I be able to test these? and make sure they work before i pop them into my sproggy?

Thanks

edit... would anyone have any spare t6's that they'd like to sell? I would like to buy maybe 2 off of someone if the price is right.

thanks.

**mp3z24** · 05-14-2002, 10:54 AM

solution to my sproggy problems

you can get the renco transformer, you might have to pay for it.
there is a minor modification that you have to make to it, but after that, it is a direct replacement for the coilcraft T6.

please read the thread and you will see how to modify the renco to fit the sproggy design. if you have any questions ask me or there are a few others who have done this, but i cant think of them off the top of my head.

for the modification, i think it would be easier to de-solder and resolder the leads, instead of cutting the legs like i did. you will understand when you read the thread.

~Mike

Thread: Sproggy parts problems: alternatives..

LinkBack

Thread Tools

Search Thread

Display

Sproggy parts problems: alternatives..

I noticed in the sproggy picture..

Bookmarks

Bookmarks

Posting Permissions