Bridge supports crafted

Posted on September 15, 2014

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Njay got me not just the bridges but also some kind of ultralight plastic material plank to use as support for them. This mechanical support is of critical importance for the survival of the bridge circuits, because the only mechanical attachment between the bridges and their big heavy heat sinks are the electrical pins of the power MOSFETs. And like dear Mr. Murphy has taught us, they will break as soon as they can. Unless we do something about it.

So, we’ve decided to fixate both heat sinks in a rigid (but vibration-absorbing) platform. This is what came out of my creative crafts process…

20140831_bridge_cradle

Power bridge rigidly installed into a plastic cradle. The cradle itself is easily removed / inserted onto the Trike’s chassis. The malleability of the “platform” material allowed me to cut holes and slits that snugly fit on the Trike’s large structural screws, holding it solidly in its place.

The add-on communications board was designed to fit directly at the top of the old model of heat sink and so function as a mechanical fixation between the two sinks. But since Njay decided to upgrade the sinks to larger ones, I had to come up with a new fixation method. I again turned to plastic due to its flexibility and stress absorbance, as well as its tool friendliness. It is also an electrically insulating material, which helps in this case because the sinks can be oppositely polarized (they are part of the electrical connection of the FETs).

Cradled power bridge, with the add-on comms board on top acting as a mechanical crossbar that keeps the sinks steady.

Cradled power bridge, with the add-on comms board on top acting as a mechanical crossbar that keeps the sinks steady. All nuts are “nylock” to prevent them from falling off due to vibration.

And let's not forget the little hole on the bottom to reach the current limit potentiometer.

And let’s not forget the little hole on the bottom to reach the current limit potentiometer.

Although I did forget it. It took some effort to make it after assembling the whole thing (too lazy to disassemble and reassemble it all again).

And finally, here’s how the whole thing looks in the end, with both bridges safely attached to the Trike.

20140831_both_bridges_perspective

The Low Rider is coming to town…

(to be continued…)Lisbon_MMF_logos_Banner_big

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