DC Motor Forward/Reverse Control

Thread Starter

fignewton83

Joined Nov 6, 2021
12
Really, with the circuit shown in posts 11 and 12, there is no chance of short circuiting the power source. If both buttons are pressed nothing will happen. because both sides of the motor will be tied to the same polarity. But it will be hard on the switch contacts because releasing either button will result in dynamic braking of the motor by momentarily running it as a generator feeding a short circuit. That will tend to stop the winch very rapidly, but it will also be hard on both the motor and the switches. So while it will work it is a compromise between simplicity and switch life. If the buttons are not snap-action switches it may work out that slowly releasing the button so that the motor can coast to a stop will be an option. You can connect a 12 volt incandescent bulb across the motor to see the effect, and if it even can be reduced by the partial button release trick.
Yes I was surprised once I had the diagram and worked through it in my head, that no short circuit was possible. Is this not a true H bridge configuration, which does suffer from the short condition if all switches are connected?

Thanks for the detailed breakdown. Very good explanation. And I love the light bulb suggestion to demonstrate what you explained.

I wired this all up and I can do the slow release causing the motor to spin down. But its only like 20% success rate. At the end of the day this is version 1 and will only need to get me through a handful of days out on the water. Over the winter I'll work on a more appropriate solution using relays or transistors and arduino/Raspberry Pi control. Lots of plans for this project so I'm sure I'll be asking lots of questions. Thanks again.
 

Thread Starter

fignewton83

Joined Nov 6, 2021
12
If this is actually going to be installed on a Salt-Water-Boat,
those Switches will last exactly ONE Boating-Trip,
and then die a miserable death from internal corrosion.
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No intention to go out in saltwater. Although now that you mention I would like to put these to the test in those conditions. The amazon page doesn't mention anything other than IP68 and marine grade. Thanks for the heads up.
 

LowQCab

Joined Nov 6, 2012
1,931
An "H-Bridge" is a specific Circuit arrangement using Transistors,
Transistors have quite a few other rules and limitations that must be followed,
and operate in a completely different way compared to a mechanical-Switch, or Relay.

There are certain "specialized" Switches that would cause a problem,
they are referred to as having "Make-Before-Break" Contacts,
but they are actually hard to find.

If You are actually using this Winch for an Anchor on a Boat .........
You might get away with Automated-Controls in shallow Lakes and Rivers,
but in Salt-Water You would be asking for disaster, Automation = BAD IDEA.

The Software I use to make Schematics is not designed for Schematics at all.
It's called "Microsoft-Picture-It", and it's way out of date, ( I think ~2006 ??),
so it requires quite a bit of research and geeking-out on the Computer to get a copy working.
I use it because I just don't like any Schematic-Creating-Software that I've seen so far.
It's extremely versatile and easy to use,
and the learning curve is way shorter than "Photoshop" or "Gimp".
It will not run on anything above Windows-7, which is fine with Me.
.
.
.Girls(30).png
 

MisterBill2

Joined Jan 23, 2018
11,640
An "H-Bridge" is a specific Circuit arrangement using Transistors,
Transistors have quite a few other rules and limitations that must be followed,
and operate in a completely different way compared to a mechanical-Switch, or Relay.

There are certain "specialized" Switches that would cause a problem,
they are referred to as having "Make-Before-Break" Contacts,
but they are actually hard to find.

If You are actually using this Winch for an Anchor on a Boat .........
You might get away with Automated-Controls in shallow Lakes and Rivers,
but in Salt-Water You would be asking for disaster, Automation = BAD IDEA.

The Software I use to make Schematics is not designed for Schematics at all.
It's called "Microsoft-Picture-It", and it's way out of date, ( I think ~2006 ??),
so it requires quite a bit of research and geeking-out on the Computer to get a copy working.
I use it because I just don't like any Schematic-Creating-Software that I've seen so far.
It's extremely versatile and easy to use,
and the learning curve is way shorter than "Photoshop" or "Gimp".
It will not run on anything above Windows-7, which is fine with Me.
.
.
.View attachment 252128
Really, this IS an "H-bridge" circuit in the true sense. And not the first time it has been suggested in this venue. And an arduino has no part in any marine application by virtue of it being a non-protected mess of circuit boards.
I do suggest retaining the manual switch on the actual anchor winch, although I have not yet worked out the scheme to reliably select between local and console control. At some point local control will be handy, I am sure.
 

Thread Starter

fignewton83

Joined Nov 6, 2021
12
Really, this IS an "H-bridge" circuit in the true sense. And not the first time it has been suggested in this venue. And an arduino has no part in any marine application by virtue of it being a non-protected mess of circuit boards.
I do suggest retaining the manual switch on the actual anchor winch, although I have not yet worked out the scheme to reliably select between local and console control. At some point local control will be handy, I am sure.
The toggle switch is still installed but it's been disabled. I had intended to repurpose that switch for an anchor disconnect. There are situations in which you need to cut the anchor loose.

As for the arduino, just an idea. Some kind of microprocessor. I'm a former software developer and thought I might like some datalogging and programmatic control over some of the future components I want to install. But thats another topic for another thread.
 
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