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Main Board

Nicholas Steele edited this page Sep 5, 2020 · 6 revisions

Contents


Images

The top side unpopulated board. The bottom side of the unpopulated board.
The top side of the unpopulated board. The bottom side of the unpopulated board.

Getting Parts

Our circuit board was purchased from JLCPCB.com. We also purchased the solder paste stencil from JLCPCB. All of the parts, listed in the BOMs, were purchased from either Mouser or DigiKey, based on availability or cost.

When purchasing the parts, there are a few things to check so that there won't be a problem in your configuration.

LED Currents

The LEDs purchased will have rated continuous currents. For ours, the White LEDs were rated for 1.5A, the IR for 1A, and the UV for 0.5A. Our system is capable of running LEDs at 1A max. This is fine for White and IR, but the UV may burn up at this current, so we had to change the current output for this LED. To configure the maximum current a channel can output, resistors R66, R73, and R76 must be changed. You can find the values in table 6 of this datasheet for the CAT4101, partially repeated below. For 1A LEDs, the resistor value is 549Ω, and for the 0.5A UV LED, it is 1050Ω. Rounding these up to standard values, we get 560R and 1k, respectively (1k is rounded down but by a small enough value that it is acceptable).

Excerpt from Table 6 of CAT4101 datasheet:

LED Current [mA] REST [Ω]
100 4990
100 4990
200 2490
300 1690
400 1270
500 1050
600 866
700 768
800 680
900 604
1000 549

If you elect to change one of the resistor values above, I would recommend also changing the value of a potentiometer. Since the highest usable resistance is around 5kΩ, the sum of the setting resistor (R66, R73, or R76) and the max value of the current adjustment potentiometer (3_ADJ, 2_ADJ, or 1_ADJ, respectively) should be around 5kΩ too.

Fuses

Each channel is individually fused. There is also a fuse F1 for the mainboard. I made F1 optional, and by default, it is not used. To use it, get a ~4A fuse and cut the indicated copper off the board.

Assembly

Testing

Uploading Software

Making Connections