It is also possible to control the LED strip with a commercial controller as shown in the drawing below. However, realize that you must use a 5V power supply for both the LED strip and controller. This setup can be used to control the LED strip, used as a tester for the LED strip, or used to control longer strips using the power connection scheme from the first drawing.

While these controllers have 200 different sequences, you will most likely find that they will still be lacking in the sequences that work for you. As well, you will not be able to attach an accelerometer to one of these modules.

A topic that is becoming more and more concerning to me as I build these things is surge suppression. While there are many devices to prevent damaging surges to the 120VAC/240VAC Shorepower inlet, almost nothing has been done with RV protection in respect to DC powered devices, which can be susceptable to the same kind of power surges:

• Nearby Lightning Strikes
• AC power surges coupled to the DC system via the RV's Converter.
• DC Automotive problems, including:
  • Connection and disconnection of the tow vehicle from the RV while running.
  • Starting and stopping the tow vehicle when connected to the RV.

These power surges typically occur on the direct DC line as when the Tow Vehicle is connected to the RV, it's battery (and thus the RV's DC system) is connected to the Tow Vehicle as well. Some of the voltage surges during the common events described above can spike at over 100V, which is felt by every unprotected circuit. The next time your RV's LED strip fails, you may want to ponder this source.

There are two popular ways to protect DC circuits from these voltage spikes; MOV (Metal Oxide Varistors) and TVS (Transient Voltage Suppressors). Of the two, MOVs are more tricky because their failure (which is inevetable) can be spectacular, and in the worst case, can start a fire. Also, MOVs are more suited to AC powerline voltages, although there are some low voltage MOVs designed for DC applications.

Suppressor failure. Both MOVs and TVS devices are failure prone. When failed, MOVs typically open, while TVS typically short - although they can open on occasion. The design challenge is to remove the device from the circuit when this occurs.

TVS devices are easier and more reliable to accomplish with the addition of a series fuse. The TVS quickly shorts out when it fails, blowing the fuse, and thus is removed from the circuit. The MOV on the other hand, generally experiences some degree of thermal runaway, which can result in temperatures over 200Deg F. Further, this is a slow process and it typically does not result in a blown fuse.

Therefore, the protection mode for MOVs are thermal fuses. A thermal fuse, as it's name suggests blows at a specific temperature rather than current. Two ways of designing this circuit is to use an internal or external thermal fuse. An internal fuse is built into the MOV, often called TMOV (Thermally protected MOV), and is matched to the MOV's failure characteristics for reliable safe disabling. The other method is to use an external thermal fuse that the designer matches (and tests) to ensure they are properly matched.

Unfortunately there are no TMOVs that are sufficient for low voltage DC applications (5~15VDC), and the typical hobbyist does not have the wherewhithall to perform UL Certification testing on their circuit.

For this reason, the TVR is a far superior selection for hobby type applications, as they destroy themself fast enough to blow a series fuse without having to consider thermal issues.

The option for the Cylon Eye is to connect two TVS diodes between the Cylon Eye and driver board; one protecting the Data line, and one protecting the 5VDC line. Note that a LED can be used to show the state of the TVS. If the LED is on, the circuit is being protected. If off, then the fuse has blown, presumably due to a failure event.

At this point, I am in the testing phase of circuit protection devices and will publish an update with part numbers when completed.