January 18th, 2014
I needed some simple wifi antennas so I made some using 12 gauge copper wire and SO-239 couplers
Start by hollowing out the coupler
There is a small ridge the keeps the insulator at the end of the pin
The easiest way to remove it is to chuck it in a drill and file it off
Them you can cut the edge of the outer casing into a small tab. Then reassemble the guts but without that ridge the insulator will go all the way down
I cut the edge to match that depth
Now you can solder on a BiQuad of about 1.2 inches per side and find a suitable reflector
I used a 5 1/4 floppy drive platter
Other stuff like steel switch plates works too as wel as regular chassis mount SO-239′s. i think the coupler makes adjusting the reflector position easier
Not as cool as the circularly polarized WiFi antennas I made for a long range link
They also have SO-239′s so I can use the same radios
N connectors would have been a better choice
January 18th, 2014
My friend John was over and asked me if the CNC machine could be used to drill PC boards. I said sure, it could even route them too
So I decided to give it a try. I found a simple QRP transmitter design which I could use for an arduino project and tried to make a couple
I built a 20M and a 40M board. They worked so well I’m going to route 2 more for 80M and 160M
January 18th, 2014
I started building CNC machines long ago. My first inspiration came from Bruce Shapiro’s eggbot. I tried a few variations of it and even the board from evil mad scientist.
One day my friend Joe told me he was interested in CNC. I told him I had played with it for years but never seriously committed to it. We decided to build one at work over lunch. Doing a little bit each week. We only have one day a week we can get together
It is so close but only using 3 or 4 hours a week has been a little limiting. We got the x and y done and some tuning so it can now plot pictures using a sharpie. We just have to finish the z axis
I recently completed a similar machine at home using some old printer parts and a dremel.
The base is a side panel from a computer UPS. A dot matrix printer gave it life to become the main carriage and the rails from an antique laserdisc player completes the z axis
It’s driven by an arduino mini running GRBL 0.8c.
There are 4 PIC 12c508 support chips. 3 handle the step direction deciding for the three axis and the 4th converts the z axis set and directions signals the a relay closure to operate a diode laser for simple engraving tasks.
I used 6 toshiba h bridge chips to drive the bipolar steppers. There are 2 solid state relays one for the dremel and the other is for a shop vac. An old compaq notebook supply runs everything.
Spindle codes control the dremel and flood coolant commands control the shop vac
The first few pieces came out pretty good
I used a dial indicator in place of the dremel initially to level the table. I managed the get it to within .008 in. It’s not really crooked but cupped slightly in the center
So far that hasn’t been a problem
Here are the first tries….
I was pretty happy with the results.
April 11th, 2013
A while ago we started an EV club at school. I had always been interested in electric cars and built a few cars and bikes of my own. I even rebuilt a few EZGO electric golf carts. One was such a monster I used it to tow a dead car out of my way.
During one meeting I was asked how hard it would be to create a charging station that would use our existing campus ID cards. That was Thursday. By that weekend I had already threw together the necessary pieces. I always shop at surplus houses and buy parts just because…
I had bought some credit card insert type readers that were listed as being used in Gas pumps. It just seemed fitting to take a gas pump reader and put it in an EV station.
I had a really rough proof of concept working on an old dell P3 before long. since my primary job was the campus card system, interfacing to that was a breeze.
I refined it a bit and brought it to school the next week for a little show and tell. Before long everybody wanted to see it and try it out. It was even put out at green week for students to try their cards in it.
Since my main goal was low price I was happy to try integrating a raspberry Pi. I was surprised to see how much faster it was than the HP and Wyse thin clients I was using before. The SD card memory was a great improvement over the Compact Flash I had been using.
There has been interest in using proximity type cards at school so I extended the software to accept both swipe and prox cards using a Weigand style reader. that reader seems to be the most expensive part in the system right now.
All inbound communications are over SSH/SCP and it will send emails out when the charge completes. There are some fancy status apps. Originally I was asked to set it up to charge $1 but right now it only validates the card as an active community member. The billing code was written in C using our card systems interface developer kit. I would like to replace this with the paypal API and make it suitable for public use
having the additonal processing power has led to the idea of using that hdmi port for some advertising. Just a free running slideshow or movie that plays in the background as the charger does its thing. the movie can be updated over ssh as needed and will be the next iteration. I will still keep the VFD display but will integrate that into a daughter card using the Pi’s internal serial pins. that save me the need for the max232 chip on the interface card.
This Pi seems to be big enough to share.
April 10th, 2011
I was pretty surprised by the price of some headlight restorer kits. I really want to clean up the headlights on a few of my cars but whats so special about the kits? I have a bunch of old headlights in the garage attic so I looked around the shelves and found a bottle of Plexiglass polish and a bottle of John Deere Spray Detailer. A couple of light passes on a standard cloth buffing wheel mounted on my bench motor yielded pretty good results. I don’t know if the rouge that was already on the wheel contributed to the shine. I have another set up there so I’ll try those too. I think I’ll post these on Craigslist now.
Here is the first one done. Pretty good compared to the other.
April 9th, 2011
For those of you with a P4 class machine the best solution is a real OS like CentOS. It has a longer life cycle than Fedora and is so easy to add packages to. My favorite P4 is the ShuttlePC These are available in many different configurations and as 1 AGP and 1 PCI slot on the back. I also have a Revo. It does have HDMI out for video but works well with a DVI to HDMI adapter cable and an old Dell monitor. You could call it a netbook with no screen. I haven’t really found a good use for this yet other than BOXEE
One Linux package I would highly recommend is Midnight Commander. Its a clone of the old Norton Commander with some really neat new tricks.
Just type “yum install mc” at a command prompt and it will do the rest Type “mc” to get started. If your functions keys wont work you can always user “esc” number instead. Hit “Esc” then “2″ for the F2 menu or “esc” then “0″ for f10 or exit. It works really well on a SSH session from a remote location and can even bring up other machines in the view panes using SSH or FTP
April 9th, 2011
I got asked a few questions about LAMP servers. Here are some of my favorite machines to use if you dont have a lot of space or power. Most of these are Pentium I Class machines unless noted otherwise.
The IBM Netvista 2200 I have a bunch of these used as Digital Signage and Media Players. They are very hard to make an OS for but if you Google Netvista 2200 Linux you will find one site with all you need. They dont have a real bios as a pc would have and only like to boot a specifically formatted kernel. These aren’t really suitable for running a backend database.They do need an external 12V power brick.
Then there is their bigger brother the IBM Netvista 2800. These are great for almost anything. They have a real bios and can run Dos apps pretty well. They will also run mos flavors of Linux and I even had on loaded with Windows 98se on a 4GB microdrive. To make that microdrive fit in the CF slot required removing the top side of the CF connector. All I did was clip the top corners with a pair of cutters and fold the side over. It snapped off cleanly. I’ve done this to to a half dozen or so and never broke and thing. YMMV. I like the fact that the power supply is built in and it has pc standard serial and parallel ports and 2 PCI slots. These make great firewalls or VOIP PBX machines.
When you really want horsepower there are plenty of small form factor (SFF) pc’s out there with P4 or better processors. In the top of this pic is a 2.4Ghz P4 Netvista box and the bottom is a 2.8Ghz P4 SFF machine many of these lack space for PCI cards even thought he motherboard will have the slots. The big Netvista has a few half height PCI slots. The middle machine is a Wyse thin client. That’s a whole different story, or at least paragraph.
I have tried many different thin clients and the HP are the best so far for my needs. The Wyse shown above is an oddity. It has a single PCI slot, a DVD and HD but is a Fat Thin Client. I like it but its external power brick gets in the way at times. The HP’s have no expansion and limited resources but can boot from a USB key so its easy to boot Linux and backup your work. I have many of these with FreeDos, DSL Linux and even one with Askozia PBX. They do run MySql pretty well but I use Monkey Web Server instead of Apache.
If you get the newer version it has a removable cover on the case that hides 2 USB slots. These can be used to hide Pen Drives and will be locked in by a standard PC cable restraint lock.
April 8th, 2011
I got this in Harbor Freight last week. I really hate taking my good tools out to the scrap pile to find the right gauge steel scrap for a project. At $10 its reasonable and has a half inch capacity which is more than enough for my needs. Can read in mm or inches with the touch of a button. Here it is on a 10mm tube.
April 7th, 2011
A long time ago I made this program to interface to my CJ7 and added a dash mode display to it.
I decided to update it for my EZGO….
Now to get this little tablet mounted to the cart
April 7th, 2011
I needed a bunch of connectors for all these controllers when I realized the power supply adapters from an ATX motherboard were the right ones….Just cut off the smaller end and solder up some longer wires…