Oxmoor DEQ-1 - Manual (Page 30)

Page 28
APPENDIX F: PRESET SELECT TALLY
The following circuit can be used to decode the Preset
Select port tallies and give an indication of the active
preset. For example, if the DEQ is set to preset 1 then
LED 1 will be “on” and the others will be “off.” Like-
wise, if the DEQ is set to preset 8 then LED 8 will be
“on” and the others will be “off.” The RC networks pro-
vide protection from static shocks. Ground for the cir-
cuit should be tied to the DEQ ground through the Pre-
set Select port (pin 14 and/or 15). The 5VDC supply
can be either user supplied or can be obtained from the
FROM
TALLY 1
FROM
TALLY 0
FROM
TALLY 2
5 VDC
5 VDC
5 VDC
5 VDC
5 VDC
5 VDC
10 K
10 K
10 K
.1 uF
.1 uF
.1 uF
1
A1
A2
LE
CS1
CS2
AO
Y1
Y2
Y3
Y4
Y5
Y6
Y7
YO
I1
I2
I3
I4
I5
I6
I7
GND
IO
Y1
Y2
Y3
Y4
Y5
Y6
Y7
YO
2
3
15
13
13
12
11
10
9
7
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
LED 1
ULN2803 74HC237
LED 2
LED 3
LED 4
LED 5
LED 6
LED 7
LED 8
4
6
5
16 8
DEQ Preset Select port (pin 13). Using this circuit and
eight momentary action switches appropriately con-
nected to the preset port (pins 1 through 8) a remote
panel can be built to change presets and indicate which
preset is active.
Note: If the DEQs connected together through preset
port are not all on the same preset the tallies cannot
properly indicate the active preset (since there is no
one active preset).