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Old 07-03-2010, 03:54 PM   #211
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Re: Hal The Van

Sofa-bed continued:
This posting covers the first part of the electrical wiring for the Sofa-bed.

WARNING: Messing with electricity can be dangerous. If handled unwisely it can cause fire, death and general mayhem. If you don't know what you are doing, hire someone who does. I'm not an electrician and have had no formal training on the subject so don't believe a word of what I say. You have been warned.

The sofa-bed's conversion from sofa to bed is accomplished with the mechanical force provided by two different actuators. The Drive Actuator causes the Seat Platform to move forward or backward. The Lift Actuator raises and lowers the Back Platform.

The actuators are powered from a 12 volt battery (or in my case two 6 volt batteries). There are two wires running to the actuator motor. To get the actuator to change direction you simply have to reverse the polarity of the two wires. That means if one wire was hooked to the positive battery terminal move it to the negative terminal and vice-a-verse with the other wire.



If you watch the in operation you might have noticed the two actuators operating at different times. This is accomplished with limit switches. A limit switch is activated when something presses against it as opposed to a wall switch which you "flip".

Here is a picture of one of the limit switches I'll be using. Notice the small lever with the roller on the top of the switch. The movement of this lever is what causes the switch to open or close.


On the left side of the switch you will see two tabs. The tabs are marked "NC" and "NO". The markings mean "Normally Closed" and "Normally Open".


What that means is if the switch is in the "open" position, which it is in the photos, there is a current path from the "Com" tab on the right of the switch to the "NC" tab. When the lever is depressed the switch is considered "closed" then the current path transfers to the "NO" tab.


Along with the limit switches I'll need a couple of diodes to control the actuators. A very simple description of a diode is that it's a electrical component that only allows current to flow in one direction. Here is a picture of one of the diodes I'll be using.


Notice the silver band around one end of the diode. The band denotes the cathode end of the diode. It helps me remember how a diode works by thinking of it's electrical symbol.


If you think of current as flowing from positive to negative you can see how the triangular shape is pointing in the direction of current flow. While the vertical line resembles a check valve that swings down to prevent the flow of current in the opposite direction. Anyone who really knows about electronics will surely tell you there are different kinds of diodes and it's more complicated than I've explained but hey, this works for me.

"I am serious ... and don't call me Shirley." Happy 30th Birthday to "Airplane!"

One more electrical part before I can start putting it all together. From Radio Shack I bought this toggle switch. It's a 3 position (ON-OFF-ON) DPDT (Double Pole - Double Throw ) switch.


The metal face-plate shows it's 3 position. The six wire connectors on the back indicates it's DPDT. I'll use this switch to reverse the polarity of the electrical connection to the actuators.

This shows how I hooked up the switch to the batteries and to the actuators.


One small note. I forgot to add a fuse to the circuit drawing which strangely enough matches what I did in real life.

continued -
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Old 07-05-2010, 02:27 PM   #212
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Re: Hal The Van

Sofa-bed continued:
Time to wire some things together. I'm using uninsulated push-on style terminal ends along with 18 gauge wire. Here I'm inserted two wires through the crimp end of the terminal, after having stripped the insulation off the wire ends..


Use a crimping tool to join the wires to the terminal.


Here's how it appears after crimping.


Since I'm using uninsulated terminals I have to insulate them. I'll be using shrink tubing. The tubing comes in different sizes so use one that's appropriate for what you're working on.


After sliding on the shrink tube you can use a heat gun.


After heating with the gun the tube will shrink to fit the terminal.


To connect the diodes I'm using butt connectors. That's them at the top of the picture.


Just slide the wire ends into one end of the butt connector and crimp it. Then slide whatever you're joining it too in the other end and crimp that end.


Here's what it looks like all joined together with a limit switch.


To mount the toggle switch to the side of the sofa-bed I used one of the left-over bracket rejects.


Then did a little cutting and drilling.


Screwed it to the side of the sofa-bed. This will not be the permanent switch. Just until the van is finished.


Here's how the switch appears from the back all wired up.


Now to attach the limit switches. Here is a diagram that shows where the two limited switches are mounted. Notice that limit switch #1 is closest to the Drive Actuator and #2 is closet to the Lift Actuator. It might be a little confusing that the switch closest to each actuator actually controls the opposite actuator.


Here is limit switch #1 mounted below the Drive Actuator. You can see that the drive rod from the actuator has the switch in the closed position. Since operation of the Lift Actuator is dependent on the position of the Drive Actuator this limit switch is wired to the Lift Actuator.


When the Drive Actuator is almost completely retracted, limit switch #1 is opened.


Here is limit switch #2 next to the fully extended Lift Actuator. The switch is opened and closed by the position of the Back Platform.


Luckily I bought 5 of the limit switches before I started. Lucky because I broke one switch and bent back the lever on another while trying to get the placement and adjustments just right.


Continued -
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Old 07-05-2010, 05:01 PM   #213
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Re: Hal The Van

Sofa-bed continued:
I've tried to come up with a way to explain how everything works together. Hopefully this all makes sense.

The sofa-bed is in the sofa position. The switch is in the off position. Both limit switches have wires running to the NC (Normally Closed) terminal on one side and the COM terminal in the other side. There is only a complete current path through the switch if it is in the Open position. The two diodes directions are opposite of each other. Both the Drive Actuator and the Lift Actuator are in the fully extended position.


Flipping the switch down begins the conversion to the bed position. Power goes to the Drive Actuator which begins to retract. This causes the Seat Platform to starts to move forward and the Back Platform to slide down the Back Support. With limit switch #1 closed and the diode stopping current flow the Lift Actuator doesn't move.


In the diagrams I'm using red to represent positive and black to represent negative with current flowing from red to black and blue shows no current flow. It's not really accurate but I think it works well enough for this explanation.

Once the Drive Actuator has retracted enough it allows limit switch #1 to open. I've placed the switch so it opens only after the Back Platform has cleared the Back Support. With the switch open the Lift Actuator starts retracting.


As the Lift Actuator retracts it lowers the Back Platform. This in turn causes limit switch #2 to close. This shows the purpose of the diodes. With the closed limit switch the Drive Actuator would stop moving except now the diode gives the electric current an alternate path around the switch so the actuator can continue to retract.


Both the actuators are fully retracted and the sofa-bed is now in the bed configuration. I show the power switch in the off position but that's not really needed. The actuators will shut themselves off after either fully retracting or fully extending.


The power switch is now flipped up to convert the bed to a sofa. Only the Lift Actuator is energized at this time. Notice the diode with limit switch #2. When the Drive Actuator was retracting this diode allowed power to bypass the limit switch. But now that the current is flowing the opposite direction this same diode prevents the Drive Actuator from extending. The practical purpose for this is that I don't want the Seat Platform to start to move until the Back Platform has risen enough to clear the Back Support.


The Lift Actuator has raised the Back Platform far enough for limit switch #2 to open. This applies power to the Drive Actuator so both are now extending.


As the Drive Actuator extends it will cause limit switch #1 to close. This is the same situation from two drawings back. Even with the limit switch closed I still want the Lift Actuator to keep extending. So this shows the second diode doing it's stuff.


Both actuators keep extending until the sofa-bed is back in the sofa configuration then they shutdown on their own.

That's it. If it needs further explaining just let me know.

PS. I've already been contacted about my description of electric current. From the wiki page on Electric Current
Quote:
A flow of positive charges gives the same electric current as a flow of negative charges in the opposite direction. Since current can be the flow of either positive or negative charges, or both, a convention for the direction of current which is independent of the type of charge carriers is needed. Therefore the direction of conventional current is defined to be the direction of the flow of positive charges.
I'm using conventional current notation.

continued -
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Old 07-06-2010, 10:38 PM   #214
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Re: Hal The Van

I'll give this a proper write up when I've farther along but got this finished tonight before dark.

Cut a hole on the inside of the rocker panel under the van


Use the cutout to reach inside the rocker panel and drill a small hole through to the outside of the van.




From the outside use the small hole as a guide to cut a bigger hole.


Install diesel fuel inlet.


It's a gas van. The diesel will be for a heater.


I started with just the tape measure then before you know it looks like a hardware store.


While the chromed diesel inlet looks pretty cool, the view from under the van shows I still have a ways to go.
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Old 07-14-2010, 08:25 PM   #215
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Re: Hal The Van

Pulled the trigger on this today. 6 gallon tank for the Webasto heater.
Ordered from Coyote-Gear.
Price including shipping: $228
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Old 07-14-2010, 08:53 PM   #216
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Re: Hal The Van

Any reason why you didn't want to use the espar airtronic 5 that runs on either diesel or regular gas. You can plumb it directly to your existing gas tank. Then you wouldn't need another fuel source.
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Old 07-14-2010, 08:59 PM   #217
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Re: Hal The Van

I bought the Webasto for $411 Canadian via ebay. It's used but works fine. I've not seen a Airtronic 5 going for anywhere near that cheap. Used gasoline (benzin on the label) Webasto/Espar heaters are few and far between. I figure I can install all the extra hardware required for a diesel heater and still come out way ahead $ wise versus a new gas heater.
And not only that but a friend who had been driving by the house spotted the van's new chrome fuel inlet and told me today that it looks pretty cool.
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Old 07-14-2010, 09:40 PM   #218
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Re: Hal The Van

Quote:
Originally Posted by WVvan
I bought the Webasto for $411 Canadian via ebay. It's used but works fine. I've not seen a Airtronic 5 going for anywhere near that cheap. Used gasoline (benzin on the label) Webasto/Espar heaters are few and far between. I figure I can install all the extra hardware required for a diesel heater and still come out way ahead $ wise versus a new gas heater.
And not only that but a friend who had been driving by the house spotted the van's new chrome fuel inlet and told me today that it looks pretty cool.
You can find the airtronic 5 going for around $1000 (+/- $300) new on ebay. That includes the 7 day timer and all install parts needed including fuel lines. With tank and used heater and parts you are coming in close to that number.

For example;
http://cgi.ebay.com/ebaymotors/Espar...#ht_1039wt_941

or another one...
http://cgi.ebay.com/ebaymotors/Espar...#ht_1737wt_941
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Old 07-14-2010, 10:22 PM   #219
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Re: Hal The Van

I've never seen a new gas Airtronic going for $700 on ebay. I don't recall having seen a new diesel going for that price either.

Those are both Hydronic (coolant heater) and diesel. Different beast.

At the moment there no gasoline Webasto/Espar heaters listed on ebay. New or used. Like I said, few and far between.
Here's a Diesel Airtonic
Espar-Airtronic-D2-Air-Heater

If you use this diesel heater (which I believe is cheaper than the gasoline model) as an example:
C $1,180.00 Approximately US $1,144.41

$411 + $228 + $120 (*extra hardware) = $759 < $1,144.41

I sure for some people the savings of nearly $400 wouldn't be worth the extra trouble. But for me, not only am I saving money but I got to draw up plans for then order my first ever custom built gas tank today. Now how neat is that!

*I've already bought all the extra hardware so I know it's around $120.
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Old 07-18-2010, 11:47 PM   #220
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Re: Hal The Van

Sofa-bed continued:

I'm going to finish the End Pieces of the sofa-bed with Formica. I've not really messed with Formica before so this will be a learning experience. All I know I learned from reading the Internet and the back of the contact cement can. Anyone reading this who wants to point out my mistakes go right ahead. I sure do.

Warning: I learned this the hard way. If you bend Formica too far it will snap. The problem is the broken edges. They can be as sharp as a razor blade. If you're not careful it will cut you long, deep and awful.

Here is full sheet of Formica as I brought it back from Lowe's. Take a friend or get a sale associate to help you roll and tie the sheet. It's a lot harder than it looks.


First things first. Disassemble the sofa-bed. Paint what won't be covered with Formica. Thanks to landyacht318 at RV.net for pointing out that I need to also paint the unseen bottom edges of the plywood furniture. Else if you spill water it could be absorbed by the plywood and cause it to swell.


Before you unroll the Formica be sure to sweep the floor clean. I'll come back to this.

The sheet is 4' X 8'. It takes up a good bit of space.


Mistake number one. I made a point of cleaning the floor before I began. But I forgot to mind the string that I cut off the roll. Sure enough it fell below the Formica and I happened to step right where the string was. That small knot is all it takes to make a crack in the sheet.


Here's Bob pointing out my mistake.


Bob loves to gloat.


Lay out the pieces I'll be covering on the sheet to get the best idea how to cut it up. Then mark the sheet with pencil. You cut the Formica so it's larger than the surface it will be applied to. The edges are trimmed down later.


The sheet was too large to feed through my table saw. To cut it I stacked four 2x4's in sets of two to raise the sheet off the floor. Place the cut marks between the two sets of 2x4's. Then used a circular saw to make the cuts.


This cutting method works well enough since the pieces will be trimmed later so the cuts don't have to be exact.


If you're using a circular saw you're supposed to cut the sheet from the bottom side to reduce chipping at the cut edges but I don't find the chipping to be that bad.


I was unable to cut around the small cracked spot but I arranged the pieces it so it shouldn't be visible when all's done.

continued -
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