Category Archives: Soldering

Open heart surgery

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OK, maybe not as dramatic, but it was just as vital.

With my final project deadline extended a week, I took a couple days of downtime to catch up on sleep. The all-nighters were adding up. Now I’m back and making some minor changes and a few fixes. Hopefully the thing will drive in reverse without catching on fire. If you don’t hear from me, send help.

Firmware for the not has been fleshed out and I’m looking forward to getting it coded. The loop is simple, checking the status of each input and setting a flag. That flag is passed to the three output functions, which run after the input stage. One exception is the turnaround() function, which is called by an interrupt on the whisker pin. Some output functions call themselves to complete a series of drive commands, for instance. This keeps things simple.

More to come.

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2015-04-23 · 20:05

All together now

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2015-04-20 · 21:18

Late night testing

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2015-04-20 · 01:30

Motor driver board

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Mounting at the rear, near the motors, his board is centered around a SN754410, a quad half bridge driver. The IC includes clamping diodes, but external Schottky diodes add an extra layer of protection from potentially ruinous flyback current.

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Filed under analog, Battery power, edX, ICs, Motors, PCB design, Robots, Soldering

Power supply board

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Power supply board for my two wheeled robot. 5 and 3.3V provided by TI LDO regulators at 3A each, and fused vbatt for the motors. PPTC rated 3A IH at 12V. Protection from over voltage condition (important when combining motors and MCUs) using crowbar circuits. Divider and space reserved for a tiny85 to monitor battery voltage.

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Filed under analog, Battery power, edX, ICs, power supply, regulators, Soldering

The rats nest is burning

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So testing on the first iteration on this board ended in a fit of curses too salty to repeat here. Decided to make another attempt, and incorporate the (painful) lessons from my first try. Opted for non-bussed perf board, and arranged components so their leads could be used to make connections.

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Much neater rats nest on the flip side. Watch this post for updates on how this tests out.

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Filed under analog, edX, ICs, Robots, Soldering

This weird part could be inside your Sorny television

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Ever heard of Bonens? Me neither, but these multi turn trimpots are very cheap. This apparent Bourns knockoff failed, so I removed it from the board and replaced it with another. Time for more testing!

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Filed under analog, edX, Soldering