If you are into building and playing around with tube radios like I am, you have probably have a similar problem as I do with powering them. Most of the old circuits were designed to run on high voltage b batteries which are no longer available. So I decided to make a universal battery box to run my radios on. To stick with the old school DIY radio builder style I decided to use an empty cigar box to make it in. You can buy or get for free empty boxes at drug stores and tobacco shops. DON'T SMOKE! Also beware this thing well produce high voltage current, probably not enough to kill you but it might give you a good jolt or even burn you, so take the appropriate precautions when building and using this device.
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Step 1: Materials
1- Cigar box, larger one big enough to hold all of the batteries.
1- 4x D-cell battery tray
4- d-cell batteries
8- 9volt batteries
6- spring clips(fahnstock clips)*
6- #6 machine screws*
6- #6 nuts*
6- solder terminals*
- 22 gauge solid copper wire
- electrical tape
- double sided foam tape
*These parts can be replaced with 6 binding posts if you like, I already had the clips so I used them*
- Wire cutter and striper
- Soldering iron and solder
- Drill and bits
- Screw driver and pliers
Step 2: Installing the D-cell Holder
For the A-Battery, heater batteries, I used a 4 cell D battery holder. Start by gluing the battery tray into the cigar box, I used some medium CA to glue it down, you can use what ever works for you. I decided to make the battery box more useful and tap the battery pack in the middle so that I could have either a 3volt A-battery or a 6volt A-battery. To do this simply solder a length of wire to the wire that connects the two rows of D-cells together and cut it long enough to reach the front of the box.
Step 3: Assemble the High Voltage B-battery
Warning- This can be dangerous, do not over heat the batteries or short them out, they might explode!!!
2nd Warning- You are essentially creating a 72volt battery, you know how a single 9volt battery well give you a little buzz when you stick it to your tung? This well do a lot more then that, be careful, don't stick it to your tung either :P
Start by arranging the 8 9volt batteries in two rows of four with the terminals alternating, see first photo, this is to make connecting the batteries in series easier. Now using electrical tape, tape the batteries together. Strip the insulation off of some 22 gauge solid copper wire. Cut the wire into short pieces and bend the ends at a right angle forming a staple that hooks into the terminals. Use these pieces of wire well be used to wire the 8 batteries in series, see third photo. After all the wires are arranged solder them to the battery terminals. *Solder the terminals as quickly as possible and do not do both terminals on a single battery one after the other, do one terminal and goto another battery and do it and then come back and do the other terminal. This is to reduce the amount of heat applied to the battery as heat well damage the batter, possibly causing it to explode.
Cut three pieces of wire, two red one black, long enough reach from where you are going to attach the B-Batter pack in the box to the front where the terminals well be. Strip just one end of each of the wire for now. Solder the black, negative, wire to the negative end of the B-Battery. Solder one of the red wires to the positive end of the B-Battery, this well be the +72 volt connection. Solder the other red wire to the wire connecting the 5th and 6th 9volt batteries together, this well be the +45 connection.
Attach the B-Battery pack to the inside of the cigar box, I used double sided foam tape for this so that when the batteries wear out I can easily remove it and replace it with a new battery pack.
Step 4: Adding the Terminals and Final Assembly.
Drill six evenly spaced holes in the front of the cigar box to attach the Fahnstock clips or Binding Posts, which ever you are using. Use a machine screw and nut to attach the clip to the front of the box and a solder terminal to the other side at each of the holes.
Solder the negative lead of the D-cell battery tray to the first terminal, left most. Solder the 3volt center tap to the second and the other end of the battery tray, +6 volt, to the third terminal. These well be the A-Battery connections.
Solder the negative wire from the B-Battery to the 4th terminal, solder the +45 volt wire to the 5th terminal and finally solder the +72 volt wire to the 6th terminal. Use some pieces of electrical tape to secure the loose wires to the inside of the box.
Use a pen and label the connections on the front of the box.
Done. Notice there is a lot of excess room in the box, this would be a good place to store wires to connect the battery box to what ever you are powering and also add more batteries. If I was to do this again I would have gotten two more batteries so that i could have had a 90 volt B-battery as well and also I might in future add a single D-cell holder to have a 1.5 volt A-battery as well making the battery box even more usefully for powering homebrew radios.