This is the SEQ-2 relay sequencer board.  It is the same size as our other boards so it will fit into the ENC-2 Enclosure. It requires a power supply of +12 volts, and a PTT input line that goes to ground to activate the relays.  The output relays are normally open until sequenced, but the 4 position slide switch can be used to reverse the sense of each relay individually.  The outputs are solder pads along the top, just above the relays in the picture.  See below for the schematic.

Note that the relays are intended to be mounted on the bottom side of the board, but will work when on the top, as shown here.  However when top mounted the NO (normally open) and NC (normally closed) markings on the board are incorrect and are reversed.  You will need 3/4 inch standoffs to mount the board, if you bottom mount the relays.

The supplied relays are rated for 10 amperes at 12 volts.

A set of LEDs and resistors are supplied so you can have a visual indicator of the relay status (one LED is a power indicator) This pic does not show the LEDs installed, but you can see where they go, the empty pads in the middle labeled JL1 through JL4.  There are not any holes for the positive side of the LEDS, if you desire to use them you will have to supply a +12 volt lead to power each one.  Click the thumbnail below to show a possible arrangement for the indicator LEDs.

Note that the blue wire connects to the +12 volt supply.  The negative LED leads connect to the JL1 to JL4 through holes on the board.  Also, with the LEDs supplied the long lead is negative (as opposed to many others).



Partial bottom view showing placement of LED dropping resistors (R3,4,5,6).  These are not needed if you do not intend to install the LED indicators.




SEQ2 Sequencer Parts List
Part Number Description Quantity
RLY1 through RLY4 G5LE-1 DC12  4
C1, C3, C5, C7, C8 0.1 uf 50 volt capacitor 5
C2, C4, C6 1.0 uf 16 volt capacitor 3
Q1 through Q6 2N3904 NPN tramsistor 6
U1 78L05 5 volt regulator 1
U2 NE555P Timer IC 1
U3 CD74HC194E 1
U4 MM74HC86N 1
D1, D2, D3, D4 1N4148 diode 4
D5 1N4001 diode 1
LED1 through LED5 Power on and relay indicator LEDs 5
RN1, RN2, RN3, RN4 Inline 4 resistor pack 6.8k 4
R1 100 K potentiometer 1
R2 47 K 1/4 watt resistor 1
R3 through R7 1.2 K surface mount resistors 5
SW1 4 pole single throw PCB mount switch 1
PCB PC board for SEQ2 sequencer 1


Here is a picture of the full kit showing all included parts.



Schematic of the SEQ-2 board. (See below for a larger schematic).