BlueClone - The Blue Room's Own Comms System

[pjb304]

There is a picture of some teardropped connections a few posts down this page http://dangerousprot...?t=3622&p=36846 Note how the tracks smoothly merge into the pad.

This helps to reduce the risk of drill breakout and also gives a little more copper in the pad area

 

It is only worth it if you cad system makes it easy (altium does, as I suspect do most of the serious cad systems), if not then forget it, too much like hard work.

 

Regards, Dan.

 

Thanks for explaining that Dan. We use Eagle (and have a pro license), and it looks like there is an add-on available which does teardrops, so I'll give it a go next time.

[boatman]

Those are only the first ten prototype boards. The design package being used is Easy PC version 16 and teardrops are easily added once the final track layout is complete. There's not much point for prototype boards as the tracking might change. Actually, it will as there are a couple of footprints which need modification and XLR connectors need to be moved. Also the board depth will have to be reduced from 80mm to 79.5mm as the case measures 79.75mm front to back and the PCB protrudes from the housing enough to cause a problem with the front and back panels.

 

I will look at increasing annular ring sizes where it wont cause a design rule conflict.

[DanSteely]

Hi Guys,

 

Any updates on the project?

[boatman]

I think Brian is back from holiday this week so we should have some comprehensive test results quite soon.

 

After that we need to finalise the PCB layout and front & back panels so we can get some real boards made.

Edited August 19, 2013 by boatman

[matt c]

Not sure who you use for PCBs, but I use pcbtrain, and have never had an issue with them. Top quality at a reasonable price.

[Dmills]

Top tip when buying more then a very few PCBs, it usually costs exactly the same for a panel full as it does for four or five, and for a small board a panel can contain a lot of boards.

Board houses will however never offer a full panel unless you explicitly ask them (So always ask).

 

For something as low density as blueclone we would normally go to Printed Wiring, for something more critical Wurth have a very good prototype shop, but that is more for fine pitch and BGA sort of work.

 

If getting boards that will not be stuffed for a while, ENIG surface remains much more solderable a year after you get the boards then OSP (Spit!), plus it looks really pretty.

 

73 Dan.

[bigclive]

I had some batches of PCBs made with immersion gold and was not impressed by their solderability unless the whole PCB was buffed to a shine with a cloth before soldering.

 

My favourite finish is HASL (Hot Air Solder Levelling) and I usually choose lead based solder so that the boards always solder beautifully even when stored for a while.

 

And talking of ill conceived ROHS "lead free" type things, I was quite amused to see on a chips data sheet that the manufacturer marked it with one of two codes for either ROHS or green. Kind of fitting really, since the lead free solders are most certainly not green in terms of the amount of lead free failures that have gone to landfill. Not to mention the hazards associated with the aggressive lead-free solder fluxes.

[cedd]

All of which is why the aviation industry are still very much a lead-free - free zone!

[Brian]

The PCBs are being designed to be manufacturable anywhere, any group buy PCBs are likely to be made in China. The finish of those is likely to be HASL (lead-free).

 

On lead-free solder, it's really not as bad as you might believe reading horror stories on-line. The solder itself is a lot better than it used to be.

 

I regularly use lead-free solder (from Rapid) and as long as your iron is hot enough (420C) it works just like lead-based stuff.

[WJProctor]

Hi,

 

Any news on when these will be available and how much they will cost yet?

 

Regards

 

James

[boatman]

The first batch of what we hope will be the final production board has been ordered and should be here very soon. We need to make a few tweaks to resistor values in the mic amp and hybrid circuits and then we can issue a final parts list.

 

It's possible we will be able to sell a kit of parts, but it is unlikely that we will be providing ready-built and tested boards as there is too much speculative investment required.

 

Thank you all for your patience.

[boatman]

Further to the previous message, the PCBs have not arrived yet so it will be a few more days before we know that they are OK.

 

We plan to offer kits of the "harder to get" components such as the PCB, case, XLR connectors and headphone amp (TCA0372). To avoid huge overheads, we will not include parts such as switches resistors and capacitors, which can all be obtained from Maplins, CPC, Farnell or RS, in the kits. We will provide a full parts list annotated with at least one set of supplier codes (probably CPC). we hope that Blue-Room members will contribute the part numbers from own favourite suppliers so that the final list will be acceptable globally.

 

In addition to the above, The Blue-Room will be providing Gerber files for the main board and the front and back panels, so that members may have PCBs manufactured independently.

 

Any comms system needs a base station/power supply and there will be a Bluecom base station design available. It will have two circuits which can run independently or joined. The PCB will fit inside the same case as the beltpack and use an external 24V wall-wart power supply. Using an external DC supply avoids any need for certification of final product as it will have no mains inside. There will be a male & female XLR pair on both the front panel and the back panel for the two circuits a DC input connector on the back panel, a latching push button switch to common the circuits and a couple of LEDs on the front panel. One LED will indicate the presence of power and the second will indicate that the two circuits are common.

[alistermorton]

The TCA0372 does seem to be fairly uncommon. Neither Rapid nor CPC list it, and Farnell only have the 8 pin dip in stock.

 

EDIT

 

Belay that - the 8 pin dip is the one we want, isn't it?

Edited October 2, 2013 by alistermorton

[Brian]

Belay that - the 8 pin dip is the one we want, isn't it?

 

It is. It's true that it's not the most common op-amp but it has a number of features which make it ideal for our application.

 

There is the L272 as an alternative but Farnell have that on EOL status although stocks are good.

 

I've attached a provisional parts list so people can see the sorts of things you need to build one. What does need adding to the list is information about things like lead pitch for capacitors.

 

The thinking behind the kit of hard to get bits is to keep shipping costs down. It's not good using a 71p op-amp if you have to buy it from the US and the supplier has an minimum order value of £30.

 

BluecomBeltpackPartsList_1_10.pdf

[boatman]

The TCA0372 does seem to be fairly uncommon. Neither Rapid nor CPC list it, and Farnell only have the 8 pin dip in stock.

 

EDIT

 

Belay that - the 8 pin dip is the one we want, isn't it?

 

Yes, that's the one. The L272 has the same pinout and drive capability and could be used as a substitute. The drawbacks being that it's three times the price and its maximum supply voltage is only 28V against the 40V limit for the TCA0372. That will be fine with a base station having a regulated supply but may fail with older base stations which aren't regulated.

 

The Bluecom Base Station will use an external 24V regulated supply so the L272M could be used in complete Bluecom systems. It just might be troublesome in older installations.