I took the circuit on pg.820 of "Practical Electronics for Inventors"(pefi) as a starting point; the one for the unipolar stepper. It would free up the -168 if I could get it to work. And since I am trying to learn a bit of electronics it will be educational when/if the problems are worked out. I will put it on my todo's list to use the -168 into the ULN2003 to control the motor.

I don't have that book, can you post a photo of what you are trying to do??

Do you want the picture from the book(what about copyrights)? Or a picture of my spaghetti set up?

Without the schematic it would be hard to understand what it is doing. But do what you are most comfortable with. Or at least a good description...

Rick

The motor turns, changes speed and direction; however, if the clock is turned off and on the motor turns off and stays off until I physically undue and redue the 9/10 connection on the 74194.

Oh! The clock is pin 11 on the 74194.

mj

-Jameco cat.# 171601 : NIPPON PF35T-48L4 (stepper motor)

-Jameco cat.# 2077263 : siemens Y23079-F1101-B301 (relay)

-100 Ohm pullup resistors

In my circuit the Stepper runs within a limited range of clock frequencies.

You could eliminate the 555 timer, 74194, 7407, and resistors. Drive the ULN2003 directly with the micro-controller and with a program, you can make the stepper move any way you wish.

BTW, where is the relay in your schematic??

The relay is the little rectangle with a curly_que in it going into pins 9 and 10 on the 74194. I should have drawn a couple of lines parallel to the inductor symbol.

Is that being used to change direction??

Those little rectangles between the 74194 and the relay represent connectors. If I manually disconnect and reconnect at these points the motor will move given that everything else is in order.

Somehow the physical disconnect-connect sequence disturbs the circuit enough to start the motor turning: Maybe producing a voltage spike or a current surge?

What are you trying to achieve with the project?? Do you have a purpose for the stepper or are you just seeing if you can make it run reliably?

Yes! The relay is used to change directions. I didn't notice your post.

I don't have much of a plan. NerdKits came into my life this winter. Thank you NerdKits. I have been for a long time wanting to do something like this. The ability to get questions answered required the internet. So all of us needing some hand holding have been waiting patiently.

I bought some components and am just trying to get them to work for me: a stepper, a dc motor, some ir leds and ir transistors, a servo(it turned out to be a continuous servo),a solenoid, some solar cells.

With two solar cells I was attempting to use their feedback to control the stepper maybe for some device to follow the sun across the sky or something.

At the moment I am setting up the wiring to use the -168 directly into the ULN2003 per your suggestion.

The stepper motor is working using the -168 into ULN2003 direct. I'm using pins PD2-5. They are updated in a timer/counter ISR. Looks like this will be alot less finicky than the other circuit.

Congratulations!!

Traveling Wilburys