ARX circuit 11

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kashken
 
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ARX circuit 11

Post by kashken »

With ARDX, I have completed circuit 3 and now circuit 11. I am gearing up to control motor rotation direction in the Making It Better section.

When I ran the motor in place of the red LED, it ran at top speed only. This leads me to believe that the diagram for changing rotation direction will only do so at top speed only. Is there a setup where I can retain variable speed to the motor AND switch direction of rotation? That is, can I drive variable speed to the motor with one Arduino pin while change direction of rotation with another Arduino pin?

By the way, can someone point to some material on relays? I have seen almost nothing in tutorials, and even less in discussions about relays. Even arduino.cc is lacking material. Is the H-bridge a better alternative for switching?

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adafruit_support_bill
 
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Re: ARX circuit 11

Post by adafruit_support_bill »

ARDX questions should be directed to oomlaut, as they are most familiar with their circuits and tutorial materials.
Is the H-bridge a better alternative for switching?
An H-bridge give you both speed and direction control. In addition, being a solid-state device, it does not have contacts that deteriorate with every switching action. These days, relays are typically used only in applications where switching is infrequent and speed control is not required.

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kashken
 
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Re: ARX circuit 11

Post by kashken »

Appreciate the feedback, but with regard to oomlout, in the past I have found them to be less than responsive, and most likely too busy to be able to field all email (they have no forums of their own). Even being most familiar with their own circuits doesn't seem to get results. In fact, they support or provide a kit similar to ARDX for SparkFun, but circuit 11 in the SparkFun kit is DIFFERENT (a less functional relay), yet the the SparkFun documentation (produced by oomlout) still points to CIRC11 at oomlout, which is the same reference for the ARDX kit, so in fact confusion is generated.

While pushing off questions about ARDX to oomlout may be the best response, I suspect it reflects that the kit may have issues and AdaFruit wants oomlout to deal with that (good luck).

Your reflection that relays deteriorate with use is something I would expect to see covered in documentation about relays (or a tutorial). However, I now understand why such material is lacking. This suggests that the ARDX kit or similar packages, should probably have H-bridge components instead.

Thanks again for the H-bridge information.

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adafruit_support_bill
 
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Re: ARX circuit 11

Post by adafruit_support_bill »

Relays still have their uses. You will find them in thermostats, toaster ovens and similar applications. Giant relay-based H-bridges are still used for large motor control where a solid-state solution would be impractical.

But your original question was in the context of small DC motor control. Solid-state H-bridges are great for controlling those.

adafruit
 
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Re: ARX circuit 11

Post by adafruit »

The book we carry, Making Things Move has tons of information about motors, relays, H bridges, etc. we strongly suggest it if you want to learn about motor control

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kashken
 
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Re: ARX circuit 11

Post by kashken »

Thanks for the book suggestion. I had put this one along with many others on my book wish list.

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colbster
 
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Re: ARX circuit 11

Post by colbster »

The circuit diagram is for an older 5 pin relay, yet the one that is included in the kit is a more complex 8 pin relay with two sets of switching sides. You have to change the wiring. See below for a crude diagram of the relay. I adjusted the circuit so in NC (normally closed), a red LED on the left side was on and my fireplace was off. When the relay was switched on the coils, a green LED went on and so did the fireplace.

coil ---- 1 2 - coil
blank - 0 0 - blank (no pins)
com -- 3 4 - com (+ power)
nc ---- 5 6 - nc (normally closed)
no ---- 7 8 - no (normally open)

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