I'm working on layout of some boards that will stack up, but I could use some suggestions for the inter-board connectors.
The following is partly to get my thoughts together on the stack-up, connections and interfaces.
Bottom line question: Backplane PCB or connector stack-up?

Board 1 / power:
External connector 1 - mains power (MTA156, 4-pin)
Connector 2 - signal coupling (MTA156, 3-pin with pin 2 absent)
Connector 3 - power (5V, 12V, 24V)
Anticipated height: 1.5 to 2" due to fuseholder, SMPS modules, isolation coil / caps
if I go with backplane, I'd move the fuseholder and mains connector to that board

Board 2 / analog:
Connector 1 - power (5V, 12V, 24V)
Connector 2 - signal coupling (companion to power connector 2)
Connector 3 - inter-board to logic
Anticipated height: 1" due to relay and receiver coil

Board 3 / digital:
Connector 1 - power (5V, 12V)
Connector 2 - inter-board to analog
Connector 3 - inter-board to optional interface
External connector x4 - KYZ (3), serial (1), all MTA100, 3-pin / right-angle
(if I go with backplane, then the serial connector could move there as a DE-9)
Four switches (DIP or separate SPST?) and seven LEDs (T-1 3/4 in right-angle holders)
Anticipated height: 0.5" - 0.75" if option board installed

Board 4 / optional interface:
Connector 1 - power (5V only)
Connector 2 - inter-board to digital
External connector 3 - DIP-16 socket (external DAC board)
External connector 4 - MTA156, 7-pin (external DAC board)

Would I be better off building a backplane board or are there stackable connectors?

 

Would I be better off building a backplane board or are there stackable connectors?

Pin headers are often used for stacking boards. Look at Arduino for example. They are cheap and widely available.

 

pin headers are common, low cost and easy to get. be aware of specs... max voltage and current. usually single pin on 0.1" headers can handle about 3A. to handle more connect several pins in parallel or scale to larger type. if working with higher voltage, you need spacing. so have some pins removed or use separate connection or use type with different pitch. but all you mention is under 30VDC so standard pitch of 0.1" (2.54mm) should do fine unless there is large current...

 

I'm working on layout of some boards that will stack up, but I could use some suggestions for the inter-board connectors.
The following is partly to get my thoughts together on the stack-up, connections and interfaces.
Bottom line question: Backplane PCB or connector stack-up?

Board 1 / power:
External connector 1 - mains power (MTA156, 4-pin)
Connector 2 - signal coupling (MTA156, 3-pin with pin 2 absent)
Connector 3 - power (5V, 12V, 24V)
Anticipated height: 1.5 to 2" due to fuseholder, SMPS modules, isolation coil / caps
if I go with backplane, I'd move the fuseholder and mains connector to that board

Board 2 / analog:
Connector 1 - power (5V, 12V, 24V)
Connector 2 - signal coupling (companion to power connector 2)
Connector 3 - inter-board to logic
Anticipated height: 1" due to relay and receiver coil

Board 3 / digital:
Connector 1 - power (5V, 12V)
Connector 2 - inter-board to analog
Connector 3 - inter-board to optional interface
External connector x4 - KYZ (3), serial (1), all MTA100, 3-pin / right-angle
(if I go with backplane, then the serial connector could move there as a DE-9)
Four switches (DIP or separate SPST?) and seven LEDs (T-1 3/4 in right-angle holders)
Anticipated height: 0.5" - 0.75" if option board installed

Board 4 / optional interface:
Connector 1 - power (5V only)
Connector 2 - inter-board to digital
External connector 3 - DIP-16 socket (external DAC board)
External connector 4 - MTA156, 7-pin (external DAC board)

Would I be better off building a backplane board or are there stackable connectors?

I think initially you can design with stackable connectors.

 

there are of course other options. backplane is one of them. the other is to use cables between boards (FPC, JST, whatever). This is a good option if one prefers easy access to any of the boards - boards can be moved away from each other while they remain connected.

 

The thing is with stackable connectors / pin headers I can't be sure how much leeway I have with the pin headers height-wise.

I'm not sure how beefy I need to go with the power cabling - I had it in mind to use MTA156 connectors, but that may be overkill? (I know with power, it's better to err on the side of overkill, but if a pair of pins on an MTA100 connector will suffice, there's that)

In the original circuit that I'm basing this on, the transformer winding feeding the 12V / 5V supplies was 11VAC, 300mA and the 24V supply (28V, actually) was derived off a 35VAC, 250mA winding.

The output transistor pair (TIP 102 / TIP 107) does have heatsinks, but evidently the power dissipation isn't much beyond the tab itself, as the aluminum tab screwed onto each is a square roughly the size of a 50-cent / 50p piece (and one of the two is even held in place with a nylon screw).

So, I think cabling would be the best way to go, it's just a matter of selecting the right system, and i'll definitely take a look at those JST cables.