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BS II & ULN 2003 for 12 VDC relay — Parallax Forums

BS II & ULN 2003 for 12 VDC relay

ArchiverArchiver Posts: 46,084
edited 2000-04-16 04:59 in General Discussion
I don't understand how to activate 12 volt relays using a ULN2003.
I'm working off of a schematic from Parallax. On the diagram they sent
me,

Stamp 04 goes to ULN pin 14 and to a relay.
Stamp 13 goes to ULN 3 and to an LED to indicate the status .

I can get the LED to light, but not the light on the relay. I have two
leads
coming from the relay that drives the lights. ON the schematic, the
12V+ from
the relay goes to ULN 2003 pin 09(the pin bottom right, opposite the
ground pin
08).


this is the passage of code for the BSII that works for the LED but not
for the
lights on the relay:


dirs = %0011111111110000 'Define output (1) ports
outs = %0000000000000000 'Set the States of the ports (all off)
clip stuff here

'turn off the red, green is on

outs = %0010001000010000 'Set pin 9 for 1.5 indicator and 13 for GREEN

'pin 11 goes OFF (RED LED)
'out11=0 '11 is red LED turn it off
'out13=1 '13 is green LED ON
'out9=1 '9 is the 1.5 minute cycle green LED indicator
'out6=0 'red relay goes out
'out4=1 'green relay goes on

the ULN2003 's 08 pin is grounded to the VSS on the stamp. Pin 09 of
the ULN
is 12VDC from the relay, and pin 14 should then complete the circuit to
the
relay /ground, I guess???

Examining the BSI example in the manual on page 99 deals with the
ULN2003 but
doesn't show any 12V lead going into pin 09 of the ULN.

Help?
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