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Kerry Design mini GRHV\GRLV and JoaMat mini T2 Group Buy


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Just got a few boards in.  From left to right... GRHV78xxx, GRHV79xxx and to the right is a new experimental digital alternator.  It’s stackable for balanced  

Look what I just found at my door step...  

Quick update on the status of the GB - we are in the process of testing the boards before sending them to the fab house for estimates. Will provide another update as progress is made.

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On 10/21/2019 at 6:40 PM, Kerry said:

Yes, R13 sets the current for the reference.  I use 4.7K and it was giving me .92mA.

Here's a shot of the positive rail...

20191021_164129723_iOS.thumb.jpg.729b9945c7e114357564f156b13a060f.jpg

(Wow - It's been sitting out for a couple of weeks and got very dusty)

On GRHV regulator board – is there a capacitor C2 between source Q3 and emitter Q4? If so - reason?

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I added this cap just in case. It was more for testing. I was trying to improve the ability to withstand near shorts. In the end I added the external current limiters. 

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Posted (edited)

Made good progress this weekend testing the PSU main board and the GRHVxxx.

Everything tested works as designed. The LED has a cool feature - it blinks at power on till the timed delay kicks in then the B+/B- are turned on and the LED stays on constantly.

Photoed is my test setup powering my electrostatic CFA.  GRHVxxx set up for 339VDC rails intended for my SRX Plus. The current draw with the CFA is quite low and over the 4+ hours, the regulated voltages were rock stable and temperature rise was minimal.

I hand-soldered everything including all SMD parts

Waiting to hear back on the quote for assembled GRHVxxx board. Should have more to share this coming week.  

Kerry PSU.JPG

Edited by mwl168
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Very nice!!!

I'm all for a batch of non-assembled boards (I actually enjoy SMD soldering), but happy to go with pre-assembled also. 

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Posted (edited)

Got quotes back from the fab house (PCBnet). All dollar amounts are USD. 

 

All boards are green, 2mm thickness.

mini T2 board: $24/pair with 3oz copper (52 pairs)

PSU main board: $10 with 3oz copper (72 pcs)

GRLV78: $5 with 2 oz copper (92 pcs)

GRLV79: $5 with 2 oz copper (92 pcs)

GRHVxxx (bare PCB): $4 with 2 oz copper (150 pcs)

GRHVxxx (partially assembled): $55 with 2 oz copper (150 pcs)

Note that the quotes are based on quantities. The cost goes up if the quantity goes down.

 

A few details about for the GRHVxxx partially assembled boards: 

1. The following parts are not populated:

  • C2M1000170D (Q3) - through-hole part to be mounted on heatsink
  • R7, R8, R9, R10 - resistors to set up regulated voltage
  • C2 - do not populate

2. Parts cost with the Mouser BOM I put together is roughly $28 without the parts listed above. The complete BOM is about $36. Tax/shipping excluded. Basically, you are paying extra $23 per board to have it pre-assembled.

3. There is a potential wait for IXCY10M90S parts (2 needed). I think we should opt to have this part un-populated if there is a long wait. There are two IXCY10M90S on each board and they are easy to solder. This will also bring the assembled PCB cost down by about $5.  

 

What we do next to move this GB forward:

All GB participants please give it some thoughts if you like to go with bare or partially assemble GRHVxxx boards and post your decision on this thread ASAP so I can update the table and get final quotes. If you decide to go with bare GRHVxxx boards, you may consider getting extras just in case. I would assume you opt for assembled GRHVxxx boards for those that do not respond.

 

Edited by mwl168
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46 minutes ago, gepardcv said:

I prefer assembled, but how much does the cost go up if most people opt for bare boards?

I already requested for quote of 50 partially assembled GRHVxxx boards. This new quote should give us a sense of what to expect.

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Due to a lot of things happening these past months I will have to opt out of this group buy. Doing a build isn't feasible for me currently (and most likely won't be for some time). Still big credit to MWL168 for arranging it.

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Thanks MWL

OK, I opt for partially assembled but I cut my order. 

GRHVxxx        2eas

GRLV78xxx    1eas

GRLV79xxx    1eas

Main Board    1eas

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I wonder what’d be the next price break for the mini T2? I have a couple of friends who are also interested in the boards, so they might buy some sets along with me.

Also, does the GRLV work as a direct plug in for the LM78xx/LM79xx? I’m thinking of using them to upgrade with stock PSU.

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I received updated quotes from the fab house. These quotes are for partially assembled GRHVxxx without the following parts:

C2M1000170D (through-hole part to be mounted on heatsink)

IXCY10M90S (potential wait due to lead time)

R7, R8, R9, R10 (resistors that set up regulated voltage)

C2 (Do not populate)

 

150 pcs - $49/pcs

60 pcs - $60/pcs 

 

11 hours ago, thuytn said:

I wonder what’d be the next price break for the mini T2? I have a couple of friends who are also interested in the boards, so they might buy some sets along with me.

Also, does the GRLV work as a direct plug in for the LM78xx/LM79xx? I’m thinking of using them to upgrade with stock PSU.

The GRLV boards can work as direct plugin for the 78xx/79xx parts.

Given the number the GB is at currently, I doubt it a few more sets of mini T2 boards is going to make significant difference in cost. Won't know for sure until I provide the actual quantity for the fab house.  

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