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Driver board construction Version A: Golf Cart Version.
This version could also be called a Generic version as it is multi-application. It is called “Golf Cart” as that is the first application this version was used on.
The driver board includes a 5V power supply, and an Atmel ATTiny85 microcontroller that controls the LED strip. The mode switches are external to the circuit board, and designed for mounting in a panel or dash board – hence the Golf Cart use.
The on-board rotary switch programs a voltage that is read by the ATTiny85 via one of it’s analog ports, which is further resolved to determine the mode (i.e. flash pattern) of the Cylon Eye. This flash pattern can be changed in programming, so any 5 patterns can be used as needed. However, the programming as downloaded will provide the following functions:
Hitch light (original function)
Cylon Eye (in Red or Green)
Marquee
Rainbow (demonstrates the full range of LED colors)
Demo – cycles through Cylon, Marquee, and Rainbow modes.
Construction of the circuit board requires downloading the construction packet as well as ordering a circuit board from OSHPark.Com.
The documentation package contains all of the necessary information to construct the board:
You will also need to purchase the components. This is the recommended list for the components and sources:
Note: A clickable list is in the documentation package.
The on-board power supply can provide 1A to 1.5A of current to the LEDs, depending on manufacturer of the L7805 regulator. For example, the Texas Instruments brand regulators can often provide 1.5A, while the other brands are typically limited to 1A.
Typically you can expect to power up to 30 LEDs with this power supply. The actual amount depends on the mode. For example, when using the hitch light – you will consume significantly more power than in the Cylon Eye mode.
If you need more current, you can use a L78S05 regulator, which is pin-compatible, but has an output of 2A.
If that is not enough, you can use an external DC-DC converter to obtain the current necessary. This does require modification of the wiring for the led strip. In this scenario, the driver would be powered normally, but the +5V of the strip would be powered by the DC-DC converter. The ground side for the LED strip, DC-DC converter and Driver Board must all be common.
This configuration can be useful for powering longer strips such as under awning strip lights.
Idea:
Since the goal of these projects is for you to use my projects as a catalyst for designing your own, and possibly improving on the design. Why not experiment a bit and design our own circuit board to be powered by a DC-DC converter. This would result in a much cleaner installation, and the goal of RV-Project.Com would be achieved.