Relay Logic
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Relay Logic


Design Principles

The dimmer circuits (next chapter) are controlled by an adjustable voltage for each color. This voltage should be “remembered” even if the AC power is turned off completely with the wall switch. While it is possible to store these voltages (or a digital equivalent) in non-volatile memory, I chose a low-tech approach using motor-controlled potentiometers.

The drive motors are small DC gear motors controlling the potentiometers such they travel from end to end in about eight seconds. This is truly a set-and-forget arrangement.

 

 

MotorControl1

 

Relay Logic and Motor Control

 

Truth table for the control logic

Channel
#

Relay
YSR

Relay
YRR

Relay
YSG

Relay
YRG

Relay
YSB

Relay
YRB

Red

Green

Blue

 

1

X

 

 

 

 

 

UP

 

 

 

2

X

X

 

 

 

 

DOWN

 

 

 

3

 

 

X

 

 

 

 

UP

 

 

4

 

 

X

X

 

 

 

DOWN

 

 

5

 

 

 

 

X

 

 

 

UP

 

6

 

 

 

 

X

X

 

 

DOWN

 

7

X

 

X

 

X

 

UP

UP

UP

 

8

X

X

X

X

X

X

DOWN

DOWN

DOWN

 

The relays YRx are activated only for the “DOWN” controls. They reverse the DC voltage polarity for the motors.
 

RelayPCB

Relay Logic Circuit Board

 

MotorControl
Assembled Relay-Motor Control Board
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