and ... Great Success!

Me working on the small power supplies.

Thursday - no, Saturday - no, Sunday, I had great success. Finally. I successfully programmed

the power supply.

Perhaps a little background information is in order. The main goal of this year is to install a completely new "camera" on our telescope here at the South Pole. Now by "camera" I do not mean what some of you have packed into your phone. Whereas your off-the-shelf point-and-shoot camera has upwards of 5 million pixels, our cutting edge camera has... 1750 pixels. The main difference between a consumer camera and our camera is that we are looking at microwave light, whereas normal cameras - and the human eye - are sensitive to optical light. The Cosmic Microwave Background (CMB) that we are interested in observing is strongest at the same wavelengths as those in your kitchen microwave.

One of my responsibilities in lab in Chicago and now here at Pole is to set up the detector readout system. A central component of the readout system is comprised of 36 computer boards, which we call "dfmux" boards. These each have their own small computer on board,

and they receive signals from the cold electronics inside of our cryostat.

The setup in lab in Chicago. The Dfmux boards are the 36 boards that have white and blue cables connected. This setup will eventually ride in the receiver cabin of the telescope.

In lab, we have been using small custom power supplies that run around $1200 a piece. Down here at pole, for the current receiver on the telescope we have been using much nicer power supplies that cost an order of magnitude more. This also means that these nice power supplies have a small computer running on them. Thus these power supplies have their own webpage for monitoring, internal voltage and current limits, an integrated fan trey, and the option to program the output voltages. These advantages combined with the fact that we know the power supplies have been successfully running at pole for 5 years means that we would prefer to power our new camera readout system with the new nice power supplies.

Thus I set off on Monday to make the new power supplies work with my readout system. On Monday I figured out how to mount my readout boards into the crate, which only required drilling a few extra holes in the side walls. On Tuesday I found the manual online and figured out how to set the IP address - thus giving me web access - and the voltages from the front control panel. Things looked good. I came back after lunch and I could not turn the power supply on.

"Plug&Play Error. PS Incompatible"

That was the extent of the information I got from the control panel. I spend all afternoon banging my head against the power supply, and figured out that if I set one of the voltages below 6.28V, the power supply became unhappy when I unplugged it and re-plugged it into the

wall. I emailed the company asking for help.

Wednesday the company had replied asking for more information, which I gave to them. Unfortunately they work 9-5 Ohio time, so I could only get one response per day. Wednesday I figured out that there were additional sensors that acted as volt-meters, and would tell the power supply to turn off if you went outside of the specified voltage range. I additionally discovered that one of the terminals of the power supply had +/- swapped from the diagram.

Thursday I got a computer program from the company which I could use to configure the power supply. Unfortunately it only ran on windows. Fortunately we have 1 windows laptop for just this purpose. I plugged in the laptop, and ... nothing.

Thursday after lunch I got Ken to help me out, and we discovered that the d-sub9 cable we were using was not straight through, meaning that pin 1 on one side did not correspond to pin 1 on the other side. This is apparently necessary for connecting computers directly together. We found a straight-through dsub9 cable, and ... SUCCESS!! We were finally able to program the power supply! Very excited.

Friday and Saturday I wired up the power supply with the final wiring scheme. In the last 30 minutes of working for that day, I had everything finished except for programming the final values. I plugged the dongle into my windows machine, and …

"Plug&Play Error. BIN eeprom FAIL"

NOOOOOOOOOO!!!! I gave up for the day and went to dinner.

Sunday we came in, and noticed that the d-sub connector was not plugged in all the way. We firmly seated the connector, and… Great Success!!! Everything is working now!

We are now all set to test out the nice power supplies with my readout boards!

Oh yeah, there was a 77% solar eclipse a week ago, which was pretty awesome. Here is my best photo:

77% Solar Eclipse