With over 6 months of production and customer feedback on the ePot.V3 MAX we are making a few changes to the MAX as part of a Rev B design that will be released soon. It was time to order more boards anyway so this is as good time to make any planned changes. A pic of the Rev B layout is shown below. We still need to go through at least one round of prototyping but after that we should be able to go straight to production.
The heart of the ePot.V3 design remains unchanged. The interfaces remain unchanged as does the general layout and the physical dimensions. The only change that is also relevant to the MINI is #1 below. Changes to the Rev B board includes the following:
1) A simpler and more robust power board (located under the main board) - not visible here
2) We've replaced the analog input switches with LDR switches similar to the V25 design except they are soldered in and not plug-ins. We never had a failed switching LDR in any of our V25 boards so I'm confident that these soldered in LDR switches will be long lived. The analog switches worked ok but could sometimes be a bit finicky so we reverted to using LDRs for input switching which worked great in the V25. The primary LDR attenuator board remains plug-in replaceable as before.
3) We substituted a DPDT relay for isolating and muting the output signals. We could have done this with LDRs as well but decided a relay would best ensure quick and definitive disconnect/muting of the output signals in case of power loss thus avoiding any artifacts, pops or bumps from uncontrolled removal of control power.
4) We eliminated the 4 isolation switches from the input and output sense signals running to the LDR calibration op amps. There was no real necessity for fully isolating these signals from the op amp inputs. Of course we retained switches on the calibration power source itself. We should have done this a long time ago even on the V25 but old habits are hard to break.
5) The final change was the elimination of the Mono switch. The inclusion of the Mono switch in earlier versions including the V25 offered limited value while significantly complicating matters especially with a pair of boards in a balanced configuration. I take comfort in its elimination knowing that there's now no possible way for any left-right channel leakage. Sometimes less is simply better. Make it so!