Introduction: Tube Breadboard
Some time ago I built a bench power supply to be used with experimental tube circuits. It was a very cool build experience and resulted in a flexible, powerful unit for supplying all of the various voltages needed with most tube projects as well as an instructable on it. At the time, I didn't have a means of prototyping the actual circuit under test yet. I needed a tube-appropriate breadboard. I racked my brain (You know how painful it is to have a racked brain!) for months to think what could I do to make such a thing. Well, at long last, here it is.
My instructable for the tube power supply can be found here:
Step 1: Found Item
Firstly, the biggest problem in making a tube breadboard is to come up with a means of holding and connecting the various components used. I vacillated between some kind of clip or spring terminal and soldered connections. Then I was in a surplus electronic junk shop in London, ON called Electric & Electronic Supply Inc (www.elelsu.com). If you are in the area I am sure they would appreciate a visit. I found the item shown in the first photo. It was perfect. It just needed some of the stuff on it stripped off to have a good foundation for building new circuits.
But the best part of this found item was the neat spring clips it had. I have looked all over but cannot find out who made/makes them. They are used by pushing the top of them down to compress the spring and inserting the lead of a component through it. There were about 85 of them on the board when I got it. I took them all off as well as the rest of the connectors and chip sockets.
Step 2: Board Construction
I am almost embarrassed to say that I did not build the breadboard. It is quite simple: a square foot or so of 1/8 inch thick perf board held off the bench by four pieces of 1/2 x 1/2 wood and small finishing nails. It could be made in about 20 minutes if the parts were on hand.
Step 3: Power Connectors
I put six five-way binding posts on the board to receive power from a power source: filament, B++, B+, C-, and Ground. I put a .01 uf/400V cap from each of the B++, B+, C- to ground to take care of noise pickup from the power supply to the board.
Step 4: Tube Sockets
The tube sockets used must be the variety which can be mounted with screws and stand-offs to the board. Since my interest at this point was in a tube circuit that used only 7 and 9-pin miniature tubes I put one of each on the board. Each pin of the sockets is wired to one of the spring clips. Each spring clip is shoved through a hole in the board drilled between the existing 1/8” holes. I used a 3/32” drill to make each clip hole and the clip just shoved in. They sit tight enough in these holes to be robust enough to hold most any component I may use. But they are also not permanently fixed to the board. They can be removed and put somewhere else as needed by the project at hand.
Step 5: Use
Use of the breadboard is now straightforward. I have built a small tube amplifier as shown in the last (and first) photo.
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