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:
https://www.instructables.com/id/Tube-Power-Supply/

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.