Arduino nixie v41 Operating Instructions Manual page 25

LEDs and front panel
Parts List:
R20 1k (*)
R21 1k (*)
R22 1k (*)
Q3 2N7000
Q4 2N7000
Q5 2N7000
LDR LDR
S1 SWITCH
LED RGB LED RGB Common anode
These are the final parts of the clock apart from the tubes, and are intended as the elements which the
user sees and touches.
This is the last step of the main board build.
Notes:
The FETs should be orientated with the flat side as shown on the board. Some FETs come with the
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leds in a row rather than in a triange. If this is the case, bend the middle lead slightly so that it fits
the holes in the board (see hint).
If you want to run more than one back light LED from the board, see the note below.
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The LDR is connected between pin 1 (GND) and pin 2 (LDS) of SV2.
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The switch is connected between pin 1 (GND) and pin 3 (BTN1) of SV2.
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The RGB LED has a flat on one side and one lead longer than the rest. The common anode is the
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longest pin. The Red cathode is next to the flat on the case. The green is next to the anode, and the
blue is on the side farthest from the flat.
The RGB LED anode is connected to pin 4 (VCC) of SV2. Red is connected to pin 1 of SV6, green to
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pin 2 of SV6 and blue to pin 3 of SV6.
(*) You can run more than one back light LED for each R,G or B channel. If you want to do this, replace this
resistor with a simple PCB link, and put a 1k resistor in series with each LED cathode instead. You can run
between 4 and 6 LEDs off the driver depending on the type and the supply (you can choose the regulated
5V or the unregulated VIN). The total current for each channel should not exceed 200mA.
Often, when running from VIN, you can leave the 1K resistor on the board and additionally place a 1K
resistor in series with each LED cathode.
Likewise, you can run two TICK LEDs in series from VIN with the 1K resistor on the board.
Calculate the current consumption of the LEDs
If you want to drive multiple LEDs or want to run the LEDs from VIN, please check the current
consumption. It is very easy.
To calculate the current drawn, you can measure the forward drop V across the LED when it is on, and
FWD