Monday, April 26, 2010

Update To Livewell Timer Circuit

A slight update to the livewell timer circuit. I changed the value and way I switched the On Time resistors. The other way it was 32 and 64 seconds, this way it will be 30 and 60 seconds. I couldn't split 150K because they don't make a 75K resistor and it didn't dawn on me until this morning to just put another 150K in parallel to get my 75K ohms. I also moved the motor on indicator LED so it lights when on Manual Fill as well as when the timer turns on. It's nice to have so you don't accidently leave it running when it's too noisy to hear it running. I add the same 680 ohm resistor and red LED to every switch on the panel as an indicator. I get both in bulk and from grab bags and it costs me about a nickel per switch to add them.

Livewell Timer Circuit - Simple Recycle Timer

I updated my livewell timer design originally made in 2004 for my previous boat. I have yet to find another livewell timer circuit on the internet so I figured I'd put mine up on the blog. All the parts should be available at any Radio Shack. The circuit features a manual fill override, 30 or 60 second switched On Time and 1-8 Minutes infinitely variable Off Time. The 555 timer must be a CMOS low power version to get these long of delays and the relay should be rated at 5 amp or better. The motor is only rated ar 2 amp but it's an *inductive load* while relays are rated for a resistive load necessitating a higher amperage relay to keep from burning the contacts from inductive kickback. The main difference between the new circuit and the old one is the addition of a selectable on time so this circuit has been field tested and proved 100% reliable over the last 6 years.

On my last boat I also added a Pulse Width Modulator motor speed control to control the water flow/pressure. The smallest livewell pump available is 500 gallons per minute which is way overkill for smaller livewells. The spray head restricts it somewhat and the common solution is to insert a valve in the line and choke it down which wastes a lot of electricity. So a 50% duty cycle from the PWM will cut your amp hour usage nearly in half ( There are circuit loses keeping us from a full 50% savings) Again the circuit is simple and the parts available at any Radio Shack. (I don't get my parts there all that often but I like to design with Radio Shack available parts so I can repair a circuit ASAP, there is always a Radio Shack fairly close by) If I do decide I need it I'll go dig out the schematic and post it on the blog.

It'll probably be a week yet before I get back to the Netbook to Chartplotter, getting my new boat on the water is a priority (This project isn't much good without a boat to test it in). I did get a Ram Mount and their Tough Tray II universal netbook/tablet PC mount which will give me the ability to rotate the computer to the front where I can see it while operating the trolling motor. Right now I'm putting the finishing touches on the design of the electronics package and I'll start pulling the wires and doing the 'rough in' so I can get the floors in and start the painting process.

Sunday, April 4, 2010

Touchscreen Controller Problems But Back In Business Now

Sorry about no posts lately. The controller board for my touchscreen kit was bad and I had to spend several days trying to get a warranty replacement. Actually I damaged the controller board by hooking it up to 5V instead of the 3.3V that's at the camera port. For most of the kits for computers other than Acer Ones they grab 5V from a USB port but the internal ports (Camera, Bluetooth) on the Acers only supply 3.3V. So in order to save a few pennies on the controller they left out a 5V to 3.3V regulator for the USB hub chip. Problem is they didn't document this and one piece of documentation listed only 5V controllers. You can see on the controller PCB where the regulator and outboard components are supposed to be and also you will find a jumper across the input and output pads of the regulator.

Even the techs at Hoda Technology are unaware of this and I wasn't going to mention it to them in fear they'd deny me a warranty replacement. It's their fault not mine that their documentation is extremely weak and 'dumbed down' and their technicians aren't properly trained/supplemented with basic details (Like supply voltages). Unfortunately this is the Status Quo throughout the computer industry with most of the so-called Technical Support being $8/hr non skilled labor reading from a troubleshooting check list. The thing is a seasoned troubleshooter like myself knows the basic steps of troubleshooting by heart and have already performed these simple tests. If I'm calling for technical assistance you can be damn sure it's a problem not listed in their cheat sheets.

But I did finally get a replacement controller board in the mail Friday and tonight I got the touchscreen working, it needs some tweaking for edge compensation and my Cubed Desktop program didn't want to play nice with it (A problem with the buggy program and not the touchscreen) but given the quick calibration it worked pretty good. Now all I have to do is wire the switch array and power LED I added to the bezel and test them, then I can button up that part of the project. Then I can move on to removing the connectors for VGA output and wired network, a few of the surrounding components, and trimming the PCB to make room for the SMA jacks for the WWAN and GPS antenna inputs. Then I can add my other options, PCB from a Bluetooth USB dongle, PCB from a wireless mouse USB dongle, and my latest feature addition an FM transmitter since the boat I just got has an AM/FM CD system already (I was using a modified for line level input  car 'power booster' amp) That eliminates another wire to plug into the Netbook2Chartplotter leaving only Power and the two antenna inputs and all at the bottom.

On the bright side the delay allowed me to get started on my other project and I've completely stripped the boat down, finished the front decks, hatches and trolling motor mount (Built from a huge 1/4" thick 'L' shaped piece of aluminum that once doubled as the heatsink and sides to a old mainframe computer power supply I stripped years ago.) Rebuilt/beefed up the transom and am about half way through redoing the trailer bunks, loading guides and wiring/lights. Still a lot to do before I'm even ready for paint, much less flooring, carpeting and the final touches. I'm doing it right so I only have to do it once and it will be a fitting home for the Netbook2Chartplotter. I'm shooting for a 'launch date' for both projects of May 1. So although it may seem like nothing is going on, behind the scenes I'm working on these projects every free minute I have. I was hoping to have the hardware part of this project done by now (And would have easily) but the 2+ week delay caused by the controller board threw the schedule all out of whack. Although I don't foresee any other delays like this, now I'll have to juggle time between the boat project and this one so I don't expect to get anything more than the button array wired and bezel closed up until I get ready to paint the boat (7-10 days). I'll have plenty of time to work on it between coats of primer and paint