CV/Gate Breakout/Buffer Board

[latigid on]

Hi, I haven't routed a board before, so I would appreciate any advice! The top ground plane has been omitted for clarity.

 

Seeing as I am using an AOUT_NG, my design has the same dimensions and mounting holes. I would stack the AOUT on top of this one with M/F standoffs.

 

The eight analogue outs and gates are brought out to a DB-25 connector. The gates are either buffered or amplified to approximately 12V, selectable via jumpers. I am using a 100k/71.5k voltage divider for approximately 2.4x gain. At a 15V supply a 100k/50k combination would provide a gain of 3. One could also mount a variable resistor instead of the jumpers for more control. This works on paper, but I am wondering if the op amp will swing right up to its rails? 

 

There is a spare buffer for the DIN sync/start connections also. I haven't figured out libraries in Eagle yet so some of the parts aren't quite right. <<Hmm, they probably need current-limiting resistors too....>>

 

I am not sure how to power things inside my SEQ yet. Building a linear triple output PSU looks to be the best, but I may try a switch- mode unit. In this case power would be supplied at J1 and a daisy chain output is at J15 on the right-hand side.

 

Perhaps it isn't quite the right thing to do, but I have isolated the grounds for the AOUT and gate signals. The ground for the gates can be tied to the same ground as the AOUT signals.

 

Lastly, I have included pins for a DC-DC converter in case the SPSU doesn't work out. The two footprints on the top left of the board are for the muRata NMV0512SC and the Recom RS-0512D. It might be wise to include an inductor-capacitor circuit which can supposedly reduce the ripple voltage down to 5 Vpp.

 

Thanks for looking and please share your thoughts!

 

 

 

 

[jojjelito]

Hi, Please remember that you need a rail to rail op amp if you want the output voltage to swing up to the rails. Otherwise you'd be within one diode drop (~0.7V) to 1.0V from that on the plus and minus side.

[latigid on]

Yes, I was thinking this. Perhaps it would be better to use a 15V supply, then it shouldn't have trouble with 12V.

[latigid on]

A few layout modifications and I have ditched the ground isolation. An LC filter was added which might be useful for a SPSU or DC-DC converter. Everything is labelled. I think I will go through 

 

http://www.dfrobot.com/index.php?route=product/category&path=135_134

 

seeing as they do DHL shipping for a cheap price.

 

Final thoughts?

 

 

[latigid on]

 

 

Looking good, all components are fitting well and it perfectly aligns with the AOUT_NG.

 

I would like to test my one first (not yet as Musikmesse is this weekend) but if anyone would like one I will offer them at USD5 + shipping.

[monokinetic]

Assuming they test out OK, I will take a PCB. Thanks for offering :smile:

[latigid on]

Everything soldered but yet to test with the SEQ.

 

 

[orange_hand]

Hi,

 

I would be interested in two boards as well :phone:

 

Cheers

orange

[gomiboy99]

Hi,

I think I could use one of these too, if there is one available.

 

Thanks

 

Tim.

[latigid on]

Okay, we can use this as an unofficial waiting list. I would like to test and document the boards first though. Just finding the time as usual... but Thursday is a holiday for me!

[latigid on]

After a few chores I managed to make all of the connections to the SEQ today. Everything fits, although I did have to shave down the SIL headers for the 15 mm clearance below the AOUT_NG.

 

I'm off for a week tomorrow, so you'll have to "watch this space" :)

 

[magneticstripper]

3 please

[Lamouette]

Watching watching.. :D 2 for me !

[mirmidi]

Hi.

One for me please !

 

[latigid on]

I think that we're over the 8 boards that I have available, but there's always the possibility that people back out etc. I am currently waiting on a bit of advice with regard to level-shifting the gates from the STM32 core, I'd rather not fry my pins :)

 

I'm happy to organise another run if there is demand for one.