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View Full Version : Adding a ULN to a 595 ?



TERBObob
03-20-2009, 05:58 PM
Ok , question ... can I add a ULN2803 inline between the LED and the RJ45 connector plug in on the OLSEN 595 board ? And if yes , could I use the same power supply for both - the OLSEN and the output from the ULN out side ?
Meaning -
If I put a ULN in between the LED ( output before it goes to the RJ45 jack) and the RJ45 jack , and use the SAME power supply cranking out the juice to the OLSEN ( 5 volt ) would this affect the ULN , or the OLSEN ?
I am wanting this so I can use relays at the end of the line of the cat 5 cable and it only makes sense to put the ULN close to the OLSEN , rather than do the line close to the other end of the cat 5 cable .
And again , would using the same power suplly have any ill effects ?

bmcgeeny
03-20-2009, 06:32 PM
Ok , question ... can I add a ULN2803 inline between the LED and the RJ45 connector plug in on the OLSEN 595 board ? And if yes , could I use the same power supply for both - the OLSEN and the output from the ULN out side ?
Meaning -
If I put a ULN in between the LED ( output before it goes to the RJ45 jack) and the RJ45 jack , and use the SAME power supply cranking out the juice to the OLSEN ( 5 volt ) would this affect the ULN , or the OLSEN ?
I am wanting this so I can use relays at the end of the line of the cat 5 cable and it only makes sense to put the ULN close to the OLSEN , rather than do the line close to the other end of the cat 5 cable .
And again , would using the same power suplly have any ill effects ?

I'm not sure what you are trying to do. The 595 and Grinch put out 5 v neg sync. We use them on PCI DIO boards to isolate and flip the voltage, but that's all done on a 595.

As for using the same power supply. I don't see why not. I ran 2 Grinches and 4 boards with 6 each 2803's on them from one power supply.

TERBObob
03-20-2009, 06:54 PM
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alwysrit2
03-20-2009, 07:59 PM
You can run relays off of the 595 without modification (through the on-board ULN's). If the 5v isn't the correct voltage you can plug it into the 2nd power plug on the board, and change the jumper at the ULN to user the 2nd voltage. The only thing I would warn you about is the sensitivity of the 595 chips. I tried to use a 595 for some 24v pneumatic valves and I kept getting a voltage back through the line when I would open the circuit (turn off the channel). I added some fast diodes to the valves which helped, but never got rid of the issue 100%.
-Don