DIY Capacitor Leak tester

If you’re like me and attend to salvage caps from discarded circuit boards or even repair electronics it’s great to have a Capacitor Leak Tester. Granted a multi meter and a ESR meter can give you a lot of info about a unknown cap but you want to know if the cap can work under full voltage load.

My little tester I’ve started drawing up plans for is simple and hopefully if all goes to plan I can test caps up to 50 Volts. I hardly deal with anything higher then 50 Volts so this will work fine for my applications.

The tester is simple to make and use. The circuit is basically a DC power supply and a analog meter. The idea is you load the cap with DC and you get the reading. A Capacitor is loaded with current until it is full then stops. On the analog meter the needle will raise until the cap is full then drop near to zero if the cap isn’t leaky. If the cap is leaky then the needle will not go near zero.

Really and truly if you have a bench power supply that can reach 50Volts or higher then all you need is to make a simple adapter, however if you don’t then you’ll have to build the power supply side.

When I was trying to draw this up I wanted to add a couple of features.
The first one I wanted to use¬†momentary switches to control it. This way if the cap wants to blow up I can stop feeding it power quickly. Another switch to the discharge circuit since you don’t want to test the cap and leave it charged. A great feature on it’s own since using momentary switches is less likely of error to happen such as leaving the discharge circuit enabled and trying to get a reading for the cap. If you keep having the discharge bleed resistor enabled in the needle on the meter probably would never move thus giving you a false reading.
The other thing I wanted to make sure of and of-course is way overkill was to use high rated resistors. If m math is right amps times volts (0.5 Amps)(50 Volts) = 25 Watts.
The highest rated resistors I have in my junk box are 7 Watt. The meter I have is from a old car battery charger and another one I could try came from a old amp meter. I just have to find the proper resistor to get the meter to full tilt.

Here is a quick rendition of the circuit.
I just need to find a Transformer that can meet my needs. The voltage doesn’t have to be exact since we don’t use caps at their full voltage rating. So if I can find a transformer that can do 40Volts then I would be happy. However I would need a multi-tap transformer that can do other voltages 5 volts, 12 volts, 20 volts and 30 volts. If anything I could use a Transformer that can handle the 40 or so volts and use this circuit.

Instead of a POT I could use a rotary switch and some fixed resistors to get the proper voltage levels to test different rated caps. For now I just need to find a proper Transformer in my little collection I got.

Simple file backup

If you are like me and like plenty of backups for small files that are used day to day you don’t need a high end over complicated backup solution. Let alone another program running in the background sucking up memory and CPU cycles.

This little gem is for Windows. It uses typical software that you probably already have. If not it’s easy to obtain and is also free/open source.

All you need is 7-zip installed and a little knowledge of BATH file programing.

First open up Notepad and copy and paste this code then save it as Backup.bat

SET hr=%time:~0,2%
IF %hr% lss 10 SET hr=0%hr:~1,1%
Set TODAY=%date:~4,2%-%date:~7,2%-%date:~10,4%-%hr%%time:~3,2%%time:~6,2%%time:~9,2%

XCOPY “D:\files\*” “D:\files-backup\backup_%TODAY%” /i /s
“c:\Program Files (x86)\7-Zip\7z.exe” a -tzip “D:\files-backup\” “D:\files-backup\backup_%TODAY%” -mx5
@RD /S /Q “D:\files-backup\backup_%TODAY%”

Naturally you’ll need to edit the code to fit your needs of what drive and directory you want to backup.
The sample code is created for copying D:\files to the final destination with the current date and time added to the directory name. From there 7-Zip is called up to compress or “Archive” the directory and when finished it delete the old directory that was copied before hand.

You could tweak things and add another line of code on the end to copy the zip archive to a flash drive or SD card. Maybe even the “Cloud”

XCOPY “D:\files-backup\*” “E:\” /i /s

Now we don’t want to run this manually since we will probably forget so we can use Task Scheduler to run the task once a day. Just load up Task Scheduler and select create task and follow the prompts and directions.

Give the Task a name, I called mine Backup Documents.
Under Triggers select Daily and the time you want it to run, I run mine at Midnight.
Under Actions select to run a program/script and browse to the Backup.bat file. I keep the file in C:\Tools.

It’s simple and easy.

A proper Minecraft server – Windows

Yes there are plenty of Minecraft server how to guides on the net but here is my take on it and how to host a server with a ISP that doesn’t like their subscribers hosting games.

This guide is for Windows. Not to mention a 64bit version.

Back in the day setting up any game server would be an all day event. However the Minecraft server is pretty simple.
The flavor of Minecraft for this is the Tekkit Legends mod. It has many mods cobbled together and makes things much easier to set up.

Download the server software from here.
decompress the zip file and move it to a location on your hard drive. For an example C:\Games\Minecraft-server

There is a BATCH file called start.bat. Right click the file and select edit.
Delete all the contents of the file and copy and paste this.
java -Xmx1024M -d64 -jar “TekkitLegends.jar” nogui

The server will use a maximum of 1GB of ram, forces it to use the 64bit of Java and everything runs on a DOS like terminal screen to save some CPU cycles. You can tweak the ram usage if you wish but if you plan to also play the game on the same machine then I wouldn’t change it. Save the file and exit notepad.

Before we go any further we need to make sure a 64bit version of Java is installed. Open a command prompt terminal by clicking on start and type in CMD. In the prompt window run this command java -version. The output should be something like this.
java version “1.8.0_101”
Java(TM) SE Runtime Environment (build 1.8.0_101-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.101-b13, mixed mode)
If it does not say 64-Bit then you’ll have to uninstall Java and install a 64bit version. I would stick with the 8u101. Select the Windows x64 Offline to download. After it’s downloaded then uninstall Java from the Control Panel/ Programs/ Programs and Features. After uninstalling you can install the proper 64-bit version. Take note, I had the 64bit already on my system but when the latest update came out the system updated to the 32bit and kinda screw things up. To fix it I had to modify the environment path and removed the listing pointing to the 32bit version.

After you have finished installing Java 64-Bit you can do a quick test run of the minecraft server. This test run will create some sample files and help speed things along when doing the final configuration. If there isn’t any issues then you can exit the server and find the file in the Minecraft server root directory called
Open it with notepad and it should look like this.

#Minecraft server properties
motd=Minecraft Server!!!!

Just copy and paste what you see here but change the following two lines highlighted in blue. Last thing you want is some one hacking your server. Take note this server setup is for creative mode and now creature spawning. It’s mostly setup for just building crap.

Save and exit notepad. Now the server is finished however there is still some work to be done. Since RCON is enabled we need to access RCON. For myself I have a dual monitor setup so one monitor has the server terminal and a RCON terminal and the other monitor has the game (client side) running. There are a few RCON clients and even a few for Android and iOS if you wish to use a smart phone/tablet. For this example we will use MCRCON. It’s a very little simple tool and you can run single commands or have a terminal session. I prefer a terminal session so I can change server values on the fly.

Unzip the file and copy the contents and paste them into the Minecraft server root directory. There is another BATCH file but we can just simply run it. Just follow the instructions and answer the questions. If you’re running the RCON terminal on the same machine then just use the IP address

Now this step is optional but I like doing it so I can be sure the server is running with Administrative rights. A little program that converts a BATCH file to a typical executive file called Bat2Exe. Just convert the BATCH file that loads the server and also go ahead and convert the RCON batch file that was created. This way you can create a shortcut and select it to run with Admin rights. Sadly you can’t just do this with a BATCH file. You can but requires extra steps and what not. This method just makes things easier in the end.

Over the years ISPs have become more strict on the bandwidth usage. Granted you can chew it up with streaming video from Netflix and YouTube but they hate it when users host games and websites. So we need a VPN like tunnel for friends to connect and play. There are tons of options but the easiest one out there is Hamachi. Just follow the install and create a VPN and give the login details to your friends. For users to connect to the Minecraft server they just select Multiplayer and select direct connect. The address they use is what is listed on the VPN that will be displayed on the Hamachi window.


Now if you wish to do this with Linux I will probably create another post for Linux. It’s kinda the same deal but with Linux we have to replace the OpenJDK with the Oracle version and stuff like that. Hamachi and MCRCON are cross-platform so it will make things a bit easier.

Wood working ideas

I dabble at times building things from wood, metal and plastic. So I thought to skip the electronic stuff for a while and go back to the hard sweat and tears of building stuff that will make the girl in your life think you’re a mans man.

Anyway, here goes a couple of ideas that I want to try but currently lack the proper tool (A Drill).
The other day I watched a couple of videos on making screw knobs.
Well it seems everyone over complicates it and doesn’t realize there is a very easy way. All you need is a Drill or Drill Press, a Drill Hole Saw, standard Drill-bit (Depending on how deep you want the grip contours.) and some sand paper.

A Drill type Hole Saw has a drill bit in the center and is typically proud to the cutting teeth of the saw. With this Hole Saw you will get a very close perfect circle and even gives you an identification of the center of the circle. Drive the hole saw into the wood and only let the saw score the circle mark on the wood. Now you can eyeball or if you’re a protectionist you can measure where you want the grip contours. Load the Drill with the other Drill-bit and drill holes around the circle for the grip contours. Put the Hole Saw back on the drill and finish cutting the circle out and you’ll have pretty much a finish product. All what is left is some sanding and attaching a bolt or nut into the knob.
You could probably use T-Nuts if you wish and also use Epoxy to secure a bolt head. Honestly I would use carriage bolts and maybe some Epoxy if I need lots of torque.

I imagine this could also be used with Aluminum and Plastic. Maybe mild steel if you have the proper tools.

Quick and dirty isolation transformer

Ever get a device that might have a faulty power supply or unsure?

Wells here is a quick and dirty solution if you don’t have a proper Isolation Transformer.
All you need are two filament transformers of the same output voltage. You can rob these from discarded wall warts. Basically we are taking a step down transformer and stepping it back up by using the secondary of the slave transformer to step it back up to mains reference voltage.

Do not put two wall warts in this configuration unless the Output is AC. If you use one or two that are DC output it will not work and you could blow up the filter cap that is inside.

For my build I used two 9v wall warts. The master that goes into the wall outlet is rated for 800mA and the slave that connects to the master transformer is rated for 500mA.
If you have mismatched transformers like I do you always want the higher rated current on the side that plugs into the wall. This way you can get the maximum current on the slave transformer. Even if you use matched transformers say 500mA for both transformers then you might get around 300/400mA. Take note the total output current wise will be whatever the slave transformer can handle. From my findings it doesn’t require it to be in-phase. Be sure to use the same output voltage. If you use a higher output voltage rated then the slave will sag a bit so instead of 120 volts you might get 110 or even 100 volts. Even if they’re matched there might be a slight voltage drop due to hysteresis. If you use a lower voltage rated for the slave you could burn up the secondary coil that is being used as the primary.

Now this is only good for devices that uses low current draw. If you need something bigger then two battery charger transformers would be better since they are rated for much higher amperage.

Just to give a better prospective here is a schematic.
Left side is the Master Transformer and the Right side is the Slave Transformer. Notice there is a center tap for the master transformer. It really isn’t needed but if you run into a center tap you can ground it. However if the slave transformer has a center tap then leave it floating.

Remember when I said it doesn’t matter about it being in-phase? Well I kinda lied a bit. On the output when you go to wire up a wall socket or some sort of plug and you want the proper live and neutral leads you want to toss it on a scope and see what lead has the top of the sine wave.
Keep in mind you do not want the chassis ground mixed with the output’s ground. Then this would defeat the purpose of the isolation.

This setup works well for tube equipment as well if you can’t find a proper transformer. You can use it to power the filament and the plates down the road. You could also toss on a voltage doubler by using two diodes and two capacitors. So even if your total output is 100 volts you could add a voltage doubler to bring it back up but you will loose some current.

Just my luck

Yesterday I was working on the CNC. I was attempting to make some v-groove like wheels for the X axis since I have a bunch of bearings I pulled from dead hard drives. Basically I was making mini Skateboard/Rollerblade wheels that are V-Grooved.

It was simple by using a hole saw to cut out the blanks from some scraps of Oak I then use my hand router with a V-Groove bit. To make the groove I used my power drill, long machine screw, a nut and a C-Clamp to hold the drill to the table top. With the machine screw holding the blank I could spin the blank over the router. by slowly raising the router on my little router table it would cut into the blank. Everything was working great until the drill suddenly stopped. I thought it was the power cord since it has seen better days so I went to replace it and noticed it was far worse then that. The drill has no bearings and only used brass bushings. The drill has to be hitting Twenty or Thirty years old. Indeed there is a bunch of slop in the bushings. Not to mention the grease was all hard and burnt.

So now I don’t have a power drill anymore. Another slap from Karma I suppose.

Reviving the CNC project

I really need a CNC for an up coming project so it looks like I am building the CNC machine once again.

The setbacks last time was not having the correct tools for the job and a few odds and ends. Instead of trying to be “Mr. Perfect” for the build I’m just going to do what I can.

It will be a threaded rod drive system. Maybe belt drive for the Z axis.

The build is very simple. I can’t draw for crap but just imagine with me here.
X axis is nothing more than a frame made out of aluminum angle bar bent into the desired square shape. Threaded rod and a single stepper in the middle. Probably a bearing on the end that doesn’t have the stepper. The Y axis would pretty much wrap around the bottom to the threaded rod and V-Groove bearings for the Gantry to ride on the sides of the X axis frame. The Gantry’s construction would be the same way of using V-Groove bearings and aluminum strip bars. A single stepper again with a threaded rod. The Z axis is still in the air because I haven’t decided on what type of spindle I want. I don’t know if I was to use a Dremel or fab something up. If anything I might just have to use a Dremel and look and see what Hope Depot or Lowes have to offer in aluminum bars and use again a threaded rod.

In all It’s just going to be a small table top unit. Probably the size of a desktop computer sitting on its side.

It will be Arduino based running the GRBL code.

The V-Groove bearings will have to be ordered probably from eBay. The rest I can buy locally.