View Full Version : uln2003 power
11-16-2006, 11:11 AM
· Would it work to use the power from the transformer powering a BS1 or 2 for the supply power say for a solid state relay using a uln2003 if the power was tapped before it went to the stamp and use the VSS on the stamp for the ground of the uln2003?
11-16-2006, 11:33 PM
·· Not sure I understand what you’re trying to do.· Perhaps if you could illustrate it we might be able to offer some sound advice on your plans.· Take care.
Parallax Tech Support
11-21-2006, 11:10 AM
ME do a diagram? Surely you jest !!!http://forums.parallax.com/images/smilies/lol.gif
·Well anyway I intend to power a BS2with a 9V or 12V wall transformer connecting to the PWR terminal and the GND. The ULN2003 takes a ground connection at pin 8 I thought Icould get this at the stamp GND terminal. I will be switching solid state relays (led's) The ULN switches the GND circuit so I need a power supply to the + plus at the solid state relays. These operate from 5V to 32V. I thought I could tie into the transformer feeding the stamp before it enters the stamp for this power as long as the transformer has enough Ma to supply all of it.
11-21-2006, 09:30 PM
Sure you could tie the uln2003 to the stamp ground but the stamp ground also needs a ground!
the + or com lead on the uln2003 will get connected to whatever voltage you will be powering (SSR). so if the SSR needs 12V then then uln2003 will need 12v on the + or com lead. this can be taken from the power before the stamp as long as the supply can handle it.
this link has a pdf with a little info on what your trying to do.
11-21-2006, 11:41 PM
If I'm reading you right, you want to power the SSR With the unregulated input supply voltage (before it goes through the 5V regulator. That fine, you're on the right track. Pin 8 of the ULN2003 goes to GND and pin 9 goes to Vin (unregulated).
11-22-2006, 02:19 AM
·· If I am reading this right, you could tie the 5V supply to any SSR input + pin and then the – input pin would go to the output of the ULN chip.· When you make the appropriate ULN input HIGH that SSR would be activated.· Since you are controlling a non-inductive load you don’t need the COM/V+ line connected, but you do need a common ground between the ULN and the BASIC Stamp.· I hope this helps.· Take care.
Parallax Tech Support