Hardware Design Guidelines

This is the area we, the DIY community, will list some general Hardware design guidelines for circuit boards. We have come into some situations where some boards are using a different standard then others, thus causing confusion when populating a board or making some ssr assemblies incompatible with controllers. Normally this would not be a problem but we are finding these things out after the fact and need to scramble to try and get it all to work properly. These are only guidelines and should not be treated as gospel. We ask you to adhere to these guidelines when designing new PCB's if you can. If you need to deviate from these guidelines we ask that you specify the deviation in the assembly notes and list that when releasing your design. This way others will know if there are any compatibility issues. If you are populating a circuit board please double check to make sure these guidelines were followed before you start populating your board based on what you read on this page.

A side benefit of following these guidelines is it will allow other to aquire the appropriate tools, if required, and they will be used continually instead of a one time deal. Also we will be able to stock up on parts should we need to make a repair or have enough on hand to populate another board of some kind. We will also be able to purchase a larger quantity of certain parts to receive price breaks in anticipation of future population. This will save all of us money in the long run.

PCB Design

Leds should be placed with the square pad as the cathode.
Diodes should be placed with the square pad as the cathode.
Power Connectors should be placed with the square pad as the ground.
Capacitors should be placed with the square pad as the cathode.
Resistor lead spacing should be .400" unless required otherwise.
Pads on the pcb should be .056" diameter with .029" hole unless otherwise required.
Mounting holes should be .300" diameter with .167" hole and there should be a minimum of 3 mounting holes per board. This will fit a 6/32 screw nicely.

Pinouts

RJ45 controller output should be pinned out as follows:
Pin 1 - +5v supply
Pin 2 - Channel 1 output
Pin 3 - reserved
Pin 4 - Channel 2 output
Pin 5 - reserved
Pin 6 - Channel 3 output
Pin 7 - Ground
Pin 8 - Channel 4 output

Power Connectors
Pin 1 - Ground

Components

Power Connectors
Molex SL Series headers for low voltage/amperage applications. .100 pad spacing. Example Mouser part number : 538-70543-0037
Molex SL Series plugs for low voltage/amperage applications. .100 spacing. Example Mouser part number : 538-50-57-9403
Molex connector terminals for low voltage/amperage applications. Example Mouser part number : 538-16-02-0102

Headers
Headers for jumpers due to design/configuration options. any .100 pad spacing header so a standard jumper can be utilized.

IC's
Sockets should be utilized on all IC's. This will prevent overheating of the IC's and ease of replacement if required.

Fuses
Fuses should be 5x20mm unless otherwise required.

Terminals
Screw Terminals should have a 5.08mm lead spacing. Example Mouser part number : 571-2828374

Notes

I have protected this page to prevent its editing so the standard stays consistent. If there is something we should add or a change be necessary please contact Macrosill or KC, your site Administrators, on the forum through a PM.

Last edit 10/02/07 : Macrosill