Briefcase Lovin'!

[Eyecannon]

Check out my new GF:

http://www.dslextreme.com/users/eyec...blingcase.html

[cloasters]

Welcome to AOA, Eyecannon! Very impressive work, well done!

[Daniel ~]

Eyecannon, Welcome! Very nicely done, just dont try to take it on an air plane anytime soon" :O}

Sorry its the world we live in" :O{

[mota]

Well done.

[Superman]

That is the sweetest one I've ever seen. Excellent job!

[dimmreaper]

1. I would have thought you would have relocated the ATX PSU's AC socket to the rear of the case.

2. What no DVD-ROM or at least CD-ROM???

3. Do you realize that the 12.6VAC transformer is either; supplying around 16V when rectified which could damage the light, or; supplying less than 16V as you are drawing more than 1amp which could damage the transformer?

4. You really should have that transformer in a grounded metalic enclosure. I've been electricuted enough time to know that.

5. Did you buy the stuff for your "12V" PSU from All Electronics? Cause I have some 25V 4700uF capacitors that look darn similar to the one you used, and that's were I got 'em.

6. Nice Job! One of the finest briefs I've seen!

[Eyecannon]

Originally posted by dimmreaper
1. I would have thought you would have relocated the ATX PSU's AC socket to the rear of the case.

2. What no DVD-ROM or at least CD-ROM???

3. Do you realize that the 12.6VAC transformer is either; supplying around 16V when rectified which could damage the light, or; supplying less than 16V as you are drawing more than 1amp which could damage the transformer?

4. You really should have that transformer in a grounded metalic enclosure. I've been electricuted enough time to know that.

5. Did you buy the stuff for your "12V" PSU from All Electronics? Cause I have some 25V 4700uF capacitors that look darn similar to the one you used, and that's were I got 'em.

6. Nice Job! One of the finest briefs I've seen!

1) Um, sorry
2) Unecessary, shared CD-ROM's over the network
3) Why would it be sending 16v? It's sending 12.6v which is within spec for the cold cathode inverter
4) That transformer is grounded to it's body, which is screwed into the PSU, which is also grounded to it's body
5) Yes
6) Thanks

[dimmreaper]

Originally posted by Eyecannon
Why would it be sending 16v? It's sending 12.6v which is within spec for the cold cathode inverter

12.6VAC becomes roughly 16VDC when you rectify it. It's a basic non-regulated PSU principal that the rectified voltage will be approximately 30% greater than the RMS AC voltage supplied by the transformer. Basically the filtering capacitor brings the DC voltage up to the AC peak voltage rather than the AC RMS voltage.

Have you checked the DC voltage with a voltage meter of some sort?

[dimmreaper]

Originally posted by Eyecannon
That transformer is grounded to it's body, which is screwed into the PSU, which is also grounded to it's body.

It's customery to seperate high voltage AC circuits from low voltage DC circuits, both for your protection and the protection of your low voltage DC parts, it's generally just considered a good idea. But hey, I can't make you do it .

[Eyecannon]

Originally posted by dimmreaper
12.6VAC becomes roughly 16VDC when you rectify it. It's a basic non-regulated PSU principal that the rectified voltage will be approximately 30% greater than the RMS AC voltage supplied by the transformer. Basically the filtering capacitor brings the DC voltage up to the AC peak voltage rather than the AC RMS voltage.

Have you checked the DC voltage with a voltage meter of some sort?

****E! You were right, but it's worse! It's got almost 20VDC! What do you suggest as a fix?

[dimmreaper]

Originally posted by Eyecannon


****E! You were right, but it's worse! It's got almost 20VDC! What do you suggest as a fix?

The voltage is so high because your not drawing a whole amp.

The transformer is 12.6VAC@1A. Less amperage will get you more voltage, and more amperage will get you less voltage.

You should use a 12V fixed linear voltage regulator good for 1A. Linear voltage regulators get hot and are terribly inefficient but they will get the job done with a minimum number of components. It'll probably cost you less than $2 for the regulator. All Electronics will have them.

[Eyecannon]

Originally posted by dimmreaper
The voltage is so high because your not drawing a whole amp.

The transformer is 12.6VAC@1A. Less amperage will get you more voltage, and more amperage will get you less voltage.

You should use a 12V fixed linear voltage regulator good for 1A. Linear voltage regulators get hot and are terribly inefficient but they will get the job done with a minimum number of components. It'll probably cost you less than $2 for the regulator. All Electronics will have them.

I just wire it up in parallel with the bridge? Would I still need the cap?

[dimmreaper]

Originally posted by Eyecannon


I just wire it up in parallel with the bridge? Would I still need the cap?

It will be a three legged IC, probably in a TO-220 package. One leg will attatch the the possitive, one leg would attatch to the negative, one leg would be your regulated output.

Yes you will still need the filtering capacitor.

[Eyecannon]

Originally posted by dimmreaper
It will be a three legged IC, probably in a TO-220 package. One leg will attatch the the possitive, one leg would attatch to the negative, one leg would be your regulated output.

Yes you will still need the filtering capacitor.

So I just stick positive on positive, negative on negative, then attach the hot line of the molex to the regulated output? I'm confused....

[dimmreaper]

Originally posted by Eyecannon


So I just stick positive on positive, negative on negative, then attach the hot line of the molex to the regulated output? I'm confused....

Yup, you got it . . . just connect the molex's yellow wire to the regulated output and the molex's black wire to the ground.

Basically a linear voltage regulator is a "smart" variable resistor that says "hey I need X impedance in order for my output voltage to match my internal reference voltage" and then sets itself to X impedance.

You can also use two trimmer pots to make a "fine tuning" adjustment circuit that attatches to the ground pin, but your application has no need for it.

BTW, be sure to get a heatsink for the regulator when you order it. If you get a TO-220 packaged regulator you will need a TO-220 heatsink. If you get a TO-3 packaged regulator you will need a TO-3 heatsink. Ect . . . . Some packagings require a mica insulator to insulate the regulator electrically from the heatsink for certain applications. TO-220 is not such a package, so it is what I'd recommend.

[Eyecannon]

I really appreciate it... you are very smart. One more question: Do I hook up the ground on the molex to the transformer or to the ATX PSU?

[dimmreaper]

Originally posted by Eyecannon
I really appreciate it... you are very smart. One more question: Do I hook up the ground on the molex to the transformer or to the ATX PSU?

The negative side of the bridge rectifier . . . .