Automotive Isolation Box
2012-09-03 01:47 by Ian
This is a brief construction log of the barrier that sits between the computer and the hostile electrical environment found in a car.- Needs to supply a regulated 5v to the computer, with a minimum of ripple.
- Needs to be able to actuate at least 4 relays for activating various things in the vehicle.
- Needs to be able to sense for the presence of voltage at four separate points.
We're going to build this one vertically off of the inside surface of the lid. Here is the terminal stack (other side of the perf board), the solid-state relays, and the supply wires to the alarm.
Second layer is a re-purposed DC/DC ATX PSU. I have removed the ATX connector.
This is the trick I'm using to mount PCBs that do not have mounting holes.
I went three layers deep to get as much circuit into this box as possible.
Inside of completed box. The top perf board contains a digital audio switch, 4 optocouplers, and a voltage monitor circuit to ensure the PSU comes up in the correct state. Since this board also has the header for the external connectors, the relay header (with inline resistors) connects here as well.
Completed box with computer interface cable attached. The three audio jacks will run to the radio (input), a non-committed input, and the stereo (as the common output). There is a third possible input, but it is connected internally via the DB15HD cable.
An abbreviated test configuration, to make sure everything plays nice.
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