Reply
 
Thread Tools Search this Thread Display Modes
 
Old 07-29-2006, 10:11 PM   #1
New Member
 
jpsdo's Avatar
 
1977 31' Sovereign
Arlington , Texas
Join Date: Jul 2006
Posts: 3
replace control panel with LEDs, Anyone??

Anyone have some simple circuit designs or ideas to replace the control panel on a 77 soverign (water tanks, voltage, amps etc) with a smaller configuration that just uses some leds maybe? I am doing a total remodel, and the gauges all spread out like they are are just too bulky. It just seems like a small cluster of LEDs could reduce the size needed for such a panel by one fourth or so. I have found one commercial unit that monitors the tanks, but I just want to avoid rewiring the whole thing. jpsdo private message or email jpsdo@hightream.net
__________________

__________________
jpsdo is offline   Reply With Quote
Old 07-30-2006, 06:22 AM   #2
Rivet Monster
 
wahoonc's Avatar

 
1975 31' Sovereign
1980 31' Excella II
Sprung Leak , North Carolina
Join Date: Jun 2003
Posts: 7,174
Images: 40
jpsdo,
The 1980 Excella has LED indicators in it. Maybe you could chase down the digram of a circuit board for that? The one used in the 1980 isn't very compact it is about 3" tall and 2' long, but that may have been the design.

Aaron
__________________

__________________
....so many Airstreams....so little time...
WBCCI #XXXX AIR #2495
Why are we in this basket...and where are we going
wahoonc is offline   Reply With Quote
Old 07-30-2006, 09:44 AM   #3
New Member
 
jpsdo's Avatar
 
1977 31' Sovereign
Arlington , Texas
Join Date: Jul 2006
Posts: 3
Quote:
Originally Posted by wahoonc
jpsdo,
The 1980 Excella has LED indicators in it. Maybe you could chase down the digram of a circuit board for that? The one used in the 1980 isn't very compact it is about 3" tall and 2' long, but that may have been the design.

Aaron
Thanks, Ill chase that one down and see what is in the board. jpsdo
__________________
jpsdo is offline   Reply With Quote
Old 07-30-2006, 10:22 AM   #4
Rivet Master
 
Zeppelinium's Avatar

 
1975 31' Sovereign
1973 27' Overlander
1977 23' Safari
Palmer Lake , Colorado
Join Date: Oct 2005
Posts: 3,908
Send a message via Skype™ to Zeppelinium
can you publish just one leg of the sensor circuit (tank sensor to LED), when you find it? Thanks.
Zeppelinium is offline   Reply With Quote
Old 08-09-2006, 10:24 PM   #5
Rivet Master
 
Zeppelinium's Avatar

 
1975 31' Sovereign
1973 27' Overlander
1977 23' Safari
Palmer Lake , Colorado
Join Date: Oct 2005
Posts: 3,908
Send a message via Skype™ to Zeppelinium
quick tank circuit

Here's a design for a fresh water tank level sensor that uses LED indicators. Current draw of the chips is very low, on the order of 1 ma (if you use the CMOS versions), but the LED will draw up to 20 ma. I'll add some sophistication if there is enough interest in the community for a kit--a circuit that pulses the LED to reduce average current draw to about 4 milliamperes, low enough that the sensors can remain on all the time you're in the Airstream.

I took a look at discrete logic chips and it seems that 74LS (low power schottky) or 74HCT (CMOS) chips have a high enough input impedance that they can detect the connection due to imersion between the tank sensors. The early 70's Airstreams had 4 wires from the tank, a ground and 3 level sensors (I call them contacts--they are just screws through the side of the tank). The circuit in the graphic provides the following indications:

Green: Top contact in water/fluid

Yellow: Middle contact in fluid, top contact out of fluid

Yel/Red: Bottom contact in fluid, upper two out of fluid (this indication has two LEDs lit up)

Red: None of the upper 3 contacts is in the water/fluid (presumably the ground contact is always in the water)

I thought about getting four colors, but orange and blue are either not readily available or don't provide enough color discrimination. However, I wanted to show a definite difference between the lower contact in the water and the lower contact out of the water, to give 4 levels.

If there is sufficient interest, I'll lay out a small PC board, about 4x6", with three indicator channels--one for fresh water and two for holding tanks (the logic for the holding tanks is a little different, since they only have three wires--ground, half full, and full).

The cost of parts for what I've done herefor one channel is about $8--the most expensive piece would be a prototyping board from Radio Shack, about $5. The logic chips (74xx04, hex inverter, and 74xx08, quad 2-input nand gate) are like $0.40 each, plus LEDs, resistors and a small three-terminal voltage regulator. You can add a second channel (black tank) for another $2, just resistors and LEDs, since the two chips have enough gates for two channels. For everyone with a pre-1975 trailer, you ony need two channels. That's it.

The prototyping board is laid out on 0.1" centers, perfect for chip sockets and spacing the LEDs. You'd have to make a new bezel on your own. If you wanted to use the existing panel (mine has 12V light bulbs--you'd have to add another chip that has open-collector outputs to handle the voltage. It's only another $0.40, but it's another 10 wires on the board and then all thew wires to the bulbs) there is a way to do it by wiring the existing light bulb sockets into the board. The logic is the same.

For 1975 and later, you need three channels (fresh water, grey and black holding tanks). But there is a twist. The three sensor wires are shorted together and the meters that indicate level sense a total resistance, as each of the sensors (contacts) is immersed. I need to do a little experimenting to see if I can create a small system to duplicate that method method of using only two wires, since only two wires show up at the control panel.

A printed circuit board that would go together without any discrete wiring would add about $30 to the project. I'd need to hear from 20 or so members who were interested in order to make that happen. Don't let all the above ancient electronic stuff scare you away. The PC board would be simplicity itself, compared to taking care of rear end sag and polishing!

Click image for larger version

Name:	freshwatertank.jpg
Views:	99
Size:	148.3 KB
ID:	24515

The resistors can't be specified without further experimenting. The pullup resistors worked fine at 56K, but my quick test of water impedence showed 50-200K with the probes in the water, so I'd be more confident if the pullups were about 350K (for CMOS--none needed for schottky). The series resistors for the LEDs are necessary to limit the current to 20 ma max, but there is a further complication. The different LED colors have different efficiencies in converting current to light. So you would want to balance the brightness by using appropriate resistors to modify the current. For example, even low efficiency green, yelow, and red LEDs have brightness specifications varying from around 5 millicandles to 700 mcd. So the series resistor would vary from about 250 ohms to 5000 ohms.

It'll be a the middle of September before I can refine this. Let me know if you're interested.
Zeppelinium is offline   Reply With Quote
Old 08-14-2006, 08:40 AM   #6
2 Rivet Member
 
firefly007's Avatar
 
1964 17' Bambi II
longwood , Florida
Join Date: Jun 2006
Posts: 76
Nice work on the LED, Led.
Here in Orlando we have a great resource for projects like this. You can see a sample of what they have online at www.skycraftsurplus.com . I have never ordered online because it is just down the street but it is a great place to find what you need. Ask for Alby or maybe it is Al B. He can pull whatever you need. I may have to build one from scratch some day because the factory units seldom work. After a month they seem to read FULL all the time.

Steve
__________________
firefly007 is offline   Reply With Quote
Old 08-14-2006, 09:29 AM   #7
Rivet Master
 
Zeppelinium's Avatar

 
1975 31' Sovereign
1973 27' Overlander
1977 23' Safari
Palmer Lake , Colorado
Join Date: Oct 2005
Posts: 3,908
Send a message via Skype™ to Zeppelinium
would you be surprised to know that every time I pass through Orlando I go there and buy a pocket full of LEDs, hardware, connectors, etc.? great place!

The only one better is Mendelson's Hardware in Dayton. Even Colorado springs has one to match, OEM Hardware, that has similar stuff and is about 6 times bigger.
Zeppelinium is offline   Reply With Quote
Old 08-15-2006, 10:48 AM   #8
2 Rivet Member
 
firefly007's Avatar
 
1964 17' Bambi II
longwood , Florida
Join Date: Jun 2006
Posts: 76
Quote:
Originally Posted by Zeppelinium
would you be surprised to know that every time I pass through Orlando I go there and buy a pocket full of LEDs, hardware, connectors, etc.? great place!

The only one better is Mendelson's Hardware in Dayton. Even Colorado springs has one to match, OEM Hardware, that has similar stuff and is about 6 times bigger.
Not surprised, you seem to be about two jumps ahead of me. Wish I was closer to one of the bigger sources.

steve
__________________
firefly007 is offline   Reply With Quote
Old 08-19-2006, 09:54 AM   #9
Rivet Master
 
Zeppelinium's Avatar

 
1975 31' Sovereign
1973 27' Overlander
1977 23' Safari
Palmer Lake , Colorado
Join Date: Oct 2005
Posts: 3,908
Send a message via Skype™ to Zeppelinium
PC Board Quote

I went out to a PCB house to see what a 6"x3" board would cost (cost of the bare board--probably add a few cents for tax and shipping).

10 - $25
25 - $12
100 - $6

How many owners out there need new control panels, or at least new tank level displays? PM me and I'll see if this should go forward as a kit or just plans.

Zep
__________________

Zeppelinium is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
GM a/c control panel rdm Mechanics Corner - Engines, Transmission & More... 5 11-11-2002 08:30 PM
replacement panel maznblu Ribs, Skins & Rivets 4 09-18-2002 06:45 PM
Should I replace the fuse box with a breaker panel? Andy R Electrical - Systems, Generators, Batteries & Solar 2 09-13-2002 11:21 PM
Control Panel Indicators niftypkg Electrical - Systems, Generators, Batteries & Solar 8 08-09-2002 04:24 PM
Control Panel indicators smily Electrical - Systems, Generators, Batteries & Solar 3 07-26-2002 04:55 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 04:34 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.