1. Home
  2. Electronics Design
  3. stepper driver help!

stepper driver help!

So I've designed a translater using basic 74 series ttl gates. I've designed both a half and full step translater. I finished soldering together the parts and i tested out the four outputs and the full step sequence was correct. However I hooked up the outputs to a ul2003 darlington array chip to the stepper motor and it would not move at all.... I probed the inputs and it looks like the translator output is greatly attenuated. is there a way to keep the origial signal without attenuating? could i just use a 7407 buffer between the driver and translator?

Reply to
Keiichi.McGuire
Loading thread data ...

The ULN2003 darlington array is made to sink current. It needs a power source. If you've got a unipolar stepper with 6 or 8 wires, your wiring could look like this (view in fixed font or M$ Notepad):

| | VCC VCC | + + | | | | ___ | ___ ___ | ___ | .-UUU-o-UUU-. .-UUU-o-UUU-. | | | | | | |2/7 ULN2003| |2/7 ULN2003| | O O O O | / \\ / \\ / \\ / \\ | (___) (___) (___) (___) | | | | | | | (created by AACircuit v1.28.5 beta 02/06/05

formatting link

It might help if you describe your stepper motor. Voltage, current requirement, how many wires (4, 6, 8).

Good luck Chris

Reply to
Chris

Can you put a number on "greatly attenuated"? A 74xx series TTL gate should be able to drive a ULN2003 with no problems (to a couple hundred mA output current anyhow). The input voltage will drop a bit, but probably still more than 2.5V. Are you pulling the supply down?

Best figure out what you are doing wrong first.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
 Click to see the full signature
Reply to
Spehro Pefhany

I have not looked at the scnematic of that driver, but... *If* it is nothing more than a number of darling transistors (as mentioned) and if the emitters go to ground, the bases will not go above (roughly) 1.3V - which is significantly less that an OC TTL output, hence the term "attenuated". Maybe that severe load over-stressed the TTL and so now cannot drive the bases enough to "saturate" the darlingtons?

Reply to
Robert Baer

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.