[hpsdr] Atlas First Light

[Christopher T. Day]

More pix of the completed Atlas #2 board sans tantalum capacitors; smaller ones on order.

 

Power off: http://www.hamsdr.com/personaldirectory.aspx?id=198

Power on: http://www.hamsdr.com/personaldirectory.aspx?id=199

 

If Bob would enhance these as well, I'll repost all three improved images. Otherwise, I'll try again, but I don't' want to wash out the LEDs with the camera flash.

 

The picoPSU-120 seems to have no problems starting and stopping when the switch changes even without any minimal load resistor.

 

A couple of thoughts now that I have one of these things physically in front of me:

 

1)     I doubt that it is worth the trouble to take out the -5VDC circuitry. It is an allowed option in the ATX spec and somebody else's ATX power supply might provide it. Anyway, we're too close to a working board to bother changing it just for that, I think.

2)     I think I/O connectors should go on the edge of Atlas daughter boards that is away from the power connector. It's fairly close between the picoPSU and the first DIN connector. The edge away from the picoPSU - bottom in my pictures - has more room for hardware connectors.

3)     2-56 hardware seems good for attaching the DIN connectors. (I think that comes out M 2.5 in metric, but somebody had better check.) My local hardware store had 2-56 x ¼" screws; these are a tad too sort as there is no length available for a lockwasher. Since the hardware store didn't have any #2 lockwashers, I went with the ¼" anyway. Screws, lockwashers and nuts ought to go on the BOM, but Mouser doesn't carry such things, apparently.

 

 

Chris - AE6VK

 

 

  _____  

From: Christopher T. Day 
Sent: Saturday, April 22, 2006 11:08 PM
To: hpsdr at hpsdr.org
Subject: [hpsdr] Atlas First Light

 

Bulletin:

 

 

I have posted a picture - only 600x800 this time - of "First Light" observed with the Atlas board.

 

http://www.hamsdr.com/personaldirectory.aspx?id=196

 

I got anxious to see something, so this is an early stage. The tantalum capacitors are not installed because of the size issue I mentioned in earlier e-mails. The ceramic bypass capacitors are all installed as well as the dropping resistors and LEDs. I will do the DIN connectors next. There is a jumper in the Power_On# position; no switch on hand. That's all that's needed for this board.

 

My picoPSU-120 is plugged directly into the ATX power connector. There is _no_ extra load resistor on the board. If you look carefully, you will notice that only four of the five LEDs are lit on the Atlas board. (The picoPSU has a red LED and a grenn LED of its own; green for power applied and red for power on, apparently.) This, as it turns out, is not wrong - the picoPSU only supplies -12V, not -5V and that's the LED that is not lit. Voltages at J20 look fine.

 

Looking good! More pix to follow.

 

 

            Chris - AE6VK

 

P.S. - "First Light" is the term for the inaugural picture from a new telescope.

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