How to run a 12VDC motor in fwd and reverse with a BS1? Need help

Kristen

Hello,

I am trying to simply run a 12VDC motor (max load 1.3A - in stall) in both directions using a BS1.· I have a darlington array (L6220) and a Tyco 12V relay (D3002), and a 12VDC 2A power supply.· I have wired it as shown below.·· The program is also below.· Once the relay is energized I start getting flakey results.·Ie. fwd when it should reverse, pulse fwd insteead of rev, pulse fwd several times, etc...· I have tried shorting OUT1 to OUT4 and IN1 to IN4 to double the motor channel, but the results were the same.· I have also tried this using a BS2 with no better results, so went back to my BS1.

Has anyone successfully gotten a DC motor to run in both directions without the stamp motor controller?

Thanks in advance!
Kristen

ps. I'm a mechanical engineer, so please be patient!



·
DO:
DEBUG "on fwd", CR
HIGH 6
DEBUG PIN6, CR
DEBUG PIN1, CR
PAUSE 2000
DEBUG "off", CR
LOW 6
PAUSE 2000
DEBUG "rev", CR
LOW 1
HIGH 6
DEBUG PIN6, CR
DEBUG PIN1, CR
PAUSE 2000
DEBUG "off ", CR
LOW 6
HIGH 1
PAUSE 2000
GOTO DO

Spiral_72

Do ya have a schematic? It would help you (and us) out a lot to actually SEE the wiring. If you're a mechanical person you can use ACAD, heck Solidworks if you want.... Or just some graph paper and scan it or take a picture of the page.

That's a pretty good sized motor! I'm sure you can drive it though. Is the motor verified good? I mean, wire the motor directly to the same power supply you plan to use in your circuit. That'd be a good check to see if the supply sags on startup and check the motor.

Lastly, I'd run the BS off a completely separate supply while your are building the system. A battery would work, or a separate wall wart. A battery would probably be safer in case your wall wart is not a clean DC supply. Only tie the battery ground and the 12V supply grounds together. That way you are insured that the control (BS) ALWAYS has power...... if the 12V supply sags when you spin up the motor, it CAN reset the BS. Believe me, you'll chase your tail finding that problem! [noparse]:)[/noparse] Later down the road, if you want to run it all off the 12V supply you can...... but get it working FIRST!

I hope some of this helps,

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"puff"...... Smile, there went another one.

Kristen

That's EXACTLY what I feel as if I'm doing - chasing my tail!· Sure do have a schematic.· The text version is in the original post and I've attached a pdf here but only look at the darlington, relay and BS1-IC positions.· NO OTHER COMPONENTS are in this loop at the moment and I'm actually trying to just debug this with a Stamp1 project board.

I tried taking baby steps as follows:

0.·· Ran the DC motor (12VDC) directly from power supply.
1.······I successfully ran the motor (12VDC) with the array using out 1 and out 2
2.······ Then wired normal and common on relay (as shown) and ran motor successfully using IN 1.
3.······ Then wired coil on relay (as shown) and used it to stop/start motor successfully using IN 1 and IN 2.
4.······ Wired energized (as shown) and tried to run in direction 1, stop, direction 2, stop, etc…· and we’re back to flakey results….works for a bit then starts yielding flakey results, will work again, then flakey again, etc…
5.· Shorted OUT1 and OUT 4 and IN1 and IN4 to double the motor channel, no change in results.
6.· Tried all the above with a BS2, using pin5 and pin 15 - no change in results.


I'm now in the process of repeating all the above steps with a 13.8VDC, 15A power supply to make sure it isn't a power spike/sag as you mentioned.

Thanks for your help!!
Kristen

Baba

Kristen: I don't feel qualified to·comment on most of your motor driving dilemma--however; I can relay to you my difficulties with erratic, goofy behavior while using an ST Micro L6220 quad switch as unipolar motor drivers---this little chip is a real high gain·powerhouse--my motors are 12v--0.8 amps in my BS2 driven·combo laser/infrared robot direction finder motor·drive---it took me a lot of headscratching (and my oscilloscope)·to figure out I needed to buffer the·significant current switching glitches from the L6220 driver lines--several different efforts at both capacitive and inductive filters finally solved the problem--you might want to see if that is at least causing part of your on/off again goofiness/also, don't ignore glitches from the relay actuation--! Incidentally, the ST Micro data sheet addresses this issue.·Best Regards, Bob

APSpijkerman

I am missing some things in the circuit,
As the motor is probably the type with brushes, it may generate
a lot of "noise"when the brushes jump over the collector and arc.
So you might want to consider putting some large ceramic capacitors
over the motor.

Also you don't seem to have a diode over the coil of the relay.
When a relay (coil) switches off the coil is still charged with magnetic
energy and it will generate a big negative voltage peak.
So you might want to put a big diode over the relais with the cathode on
the +12v and the anode at the ground.

The same goes for the motor, when suddenly the voltage is removed
with a relay it might generate a big negative voltage puls. Which might
produces arcs over the contacts of the relay, so before the relay you
might want to place a big diode.

Also when a big motor starts it might consume 3-5 times as much current
as during normal operation.
So you might want to have a biggish capacitor over the stamp to maintain
voltage over the stamp.
To prevent dropping of the voltage over capacitor you might want to consider
feeding the capacitor through a coil or diode.
If you would feed the capacitor through a diode then the motor can't
discharge the capacitor if the voltage drops for a fraction but the stamp
is still ensured of a clean voltage.



greetings Arend-Paul Spijkerman

basic stamp scope

wiresalot

To reverse the direction of a DC motor, Change the polarity on the armature.

wiresalot

NWCCTV

I had a similar issue a while ago with my Stepper motors. No matter what I tried I was getting the same result from more than one motor. I finally decided to tye in all the grounds to the same ground as my Stamp and that cured my problem. May not be your issue, but it's worth a try.