Archive Page 2

accelerator control system (1)

Now that we’re moving on the electronic rebuilding phase. Here’s a short description of how the accelerator control system will actually work.

terminal elec–FO-|…………………………………………|—-USB input
……………………………|-FO–analog control panel–|
source elec—FO-|…………………………………………|—-USB output

Within both the source and terminal electronics boxes, analog voltage control (input) and analog voltage monitoring (output) interface with the fiber optics (FO) boxes and are converted to digital FO signals. The signals are converted back to analog at the control panel. To interface with the control panel, we will be getting two USB devices: one 8-channel input (plus 2 output channels) and one 16 channel output. Both units come with enough binary digital I/O channels to choke a horse. The fiber optics portion of the system should be transparent to us, provided it functions as ordered.

This system has some useful features.

  • It incorporates full feedback for every controlled parameter. As obvious as this seems to me, there are a lot of fancy-pants scientific equipment that misses this, and thus can’t make basic determinations as to whether or not their equipment is functional.
    “What is the voltage output to the y-steerer?”
    “Uh, I turned the control knob up to 11, so I guess 11.”
    “Is the beam being steered?”
    “Uh, doesn’t look like it.”
    “So is something wrong?”
    “Uh, probably.”
  • Since we have feedback, we have the option of closing the feedback loops with controllers in the future. Process control can be tricky, so starting out your system with closed feedback control on everything leads to a lot of fighting control systems and less actual running the accelerator, so we have the option to do it later but we don’t have to do it now.
  • The control system has a natural analog breakout point at the control panel. If something isn’t responding correctly from the computer, you can stick a voltmeter in the control panel and see if you’ve got the correct signal going through, rather than trying to figure out if the baud rate on your RS232 device interface is set correctly or is your port forwarding settings mesh with the new TCP/IP management software the department installed.
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vacuum pump controller (2)

So apparently buying custom PCBs is taboo, so we’ll be rolling our own. The upside is no one outside the lab need look at our precious proprietary developmental super-secret awesomeness. The downside, is there is a lot of precision drilling in everyone’s future. Stay tuned for further developments.

vacuum pump controller (1)

It looks like a number of vendors offer short-run PCB prototype production. As much as I love playing with toxic chemicals and then properly disposing of the waste, contracting out the PCBs for our vacuum pump driver/controller units may turn out to be straight-up cost-effective, as well as a time-saver.

http://www.custompcb.com/
http://www.futurlec.com/PCBService.shtml

Others may exist as well.

  1. Finalize the layout, including the bearing RTD readout. That can be as simple as a light that turns on when the resistance of the RTD circuit goes above the 35 degC value.
  2. Find some protoytpe PCB-fab companies and get quotes for 8-12 units. They probably want the original layout file.
  3. Order the boards.
  4. Develop parts list from the prototype and notes on the circuit diagram.
  5. Order the components from any of our favorite electronics components vendors. Try to get it all in one order.
  6. When everything shows up in the lab, stuff a board and solder it. See if works in the prototype chassis.
  7. Figure out how to use the old broken controller transformers and cases to actually assemble a functioning 1/2-rack mount unit, probably requiring a new front faceplate.
  8. When one fully-built controller works, repeat to build 6 total functioning units.

#stuff2do

power supply heaven (3)

So I sent two more power supplies there on Friday, giving me a commanding 4-1 lead over Prof. Morse. The dead 100 V and 30 V supplies should be packaged up to be returned to the vendor for repair. Now I know we could fix them ourselves, but given the preponderance of busto-electronics reclamation projects in the lab, I’m deciding to let these ones go. Instead, I’ll be ordering components for DIY output protection on the replacements, with the bonus of having one extra power supply of each flavor after the repairs.

power supply heaven (2)

I sent two supplies there yesterday. One I pretty much knew was a bad idea and did it anyway. The other just decided it was sick of running the source screen and committed some sort of power supply ritualistic suicide. In any case, I’ll try to kill fewer power supplies today.

Electronics boxes (1)

It’s time to start rebuilding the electronics box for reals. For review, there are two of them: source and terminal. One is the existing blue box with the two HV supplies sitting in it. The other box will be an exact copy of that one, yet to be procured. For now, start with the terminal electronics box because that one is easier to integrate with the existing source test stand with the fiber optics.

PS=power supply

terminal electronics box:

  • x-steerer PS: DC controllable 0-30 V
  • y-steerer PS: DC controllable 0-30 V
  • fiber optics PS: DC 11.3 V fixed, 3.8 A max
  • getter heater PS: DC 18 V fixed, 6 A, on/off control
  • inductor HV: existing NEC/Glassman 60kV
  • suppressor HV: existing NEC/Glassman 60kV

For now, all the interconnections can run through an exiting hole in the case. We’ll take care of independent AC power for the box when we get the fiber optics.

You load 16 tons…

The answer is “16 tons of lead in your lab and increased interest in your project from pretty much everyone.”

First, thanks to everyone for turning over a huge task in one day. In particular, El and Dan went above and beyond to help us deal with the logistics of a 45′ flatbed in the alley. I swear they told me it was a 25′ van.

I will schedule lead awareness training for everyone who plans to so much as look at a lead brick. Until that happens, please do not touch the bricks, look at them, or consider them in any way.


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