Breadboarding/Prototyping - How to and Tips/Tricks

[Steven-H]

Gents,
How about a thread here on the best methods of prototyping and breadboarding for tube circuits ? Im about to embark on a totally custom/expensive preamp project - so I intend on doing a prototype first...

Thanks !!

[drlazybones]

I've been wondering the same thing. I'm about to do my first build but I'm not actually sure how to put the circuit together as a prototype first... I'll figure it out real quick but I'd like to read what some folks with experience do as standard practice...

[astouffer]

Personally I've never used these but they look like a good idea

http://www.tubesandmore.com/scripts/...02_EPOXYBOARDS

[aardvarkash10]

I try and do all the theoretical stuff up front so that basic blocks are settled and all that needs doing is to alter values on passives and the like. I have yet to work out how to run Spice or similar, so for me its the calculator, sketchpad and coffee technique. Using this approach, my active components (generally the larger and more expensive bits) are all determined, so I can start building.

Since my builds are all p2p, I then set up the chassis with all the required bits mounted, and start slinging solder. I now have a working (hopefully) unit that can be optomised by adding, changing or deleting the various little bits that hang off the valve sockets, tag strips and the like.

This works for me for a couple of reasons - it takes away that urge to itteratively alter a design at the breadboard stage, that urge ending up as the end itself and the design never being actualised. I'm a procrastinator at the best of times so I don't need the excuse of "just one more design change..."

Secondly, (and associated) I quickly reach the deminishing returns point and so my device moves from the workbench to the lounge (or whereever) and the various significant others can tell me what a genius I am instead of whining about my lack of attention to their need for affirmation and affection. Never underestimate the motivational power of WAF

[Loren42]

Originally Posted by Steven-H

Gents,
How about a thread here on the best methods of prototyping and breadboarding for tube circuits ? Im about to embark on a totally custom/expensive preamp project - so I intend on doing a prototype first...

Thanks !!

I do as much homework as possible, then go directly to having PCB's made. If I doubt the outcome I have prototype PCBs without solder mask and silk screen, but almost always go with productions boards the first time I build.

My recommendation is to do a paper design and "show all your work". In other words, make copious notes of all your math calculations for the design. Put those notes into a nice neat, easy to read, format in an electronic document. Describe the theory of operation in those notes as you go.

Then, publish those notes with the design schematic here or on a website and invite the gang to do a review.

Two things will happen when you do this and they will both be surprises:

1) You will be surprised at the number of mistakes you will find before you publish it.

2) You will be even more surprised at the number of mistakes or improvements others will unearth after they review it.

Having a review is like having a whole gang of engineers doing the design. You get all kinds of ideas and in the end you get to decide if you want to use them or ignore them. After all, it is your gig.

[Steven-H]

Guys,
Thanks for all the tips. I'll be building this amp on a turret board; so I figure I will lay out the components on graph paper to build out a drill template. From there, I'll put it on some plywood to make it easy to get to different components that may need adjustment, to take measurements, etc. Once I have it where I want it, then I'll disconnect what I need to; and toss it in a chassis.

-Steve

[Loren42]

Originally Posted by Steven-H

Guys,
Thanks for all the tips. I'll be building this amp on a turret board; so I figure I will lay out the components on graph paper to build out a drill template. From there, I'll put it on some plywood to make it easy to get to different components that may need adjustment, to take measurements, etc. Once I have it where I want it, then I'll disconnect what I need to; and toss it in a chassis.

-Steve

Good plan. Another tip is if you have a computer and a printer, download one of those free cad packages (TurboCAD, maybe) and do a 1 to 1 layout on that. Then print it to actual scale on the printer.

I have used either spray on glue or even glue stick on the paper to fasten it to the surface you want to cut. Tape is a bad idea, but if you really want to know why, try it yourself.

One trick is to draw a box of known height and width on the drawing page (i.e., the outline of the chassis works fine) and when you print the page, double check the known dimensions with the actual dimensions you measure of the sheet of paper. This confirms that the printer did not distort the layout, which you might not realize until after you are busy cutting metal.

[tubelab.com]

I have been prototyping circuits for nearly 50 years. Of course my abilities have improved a bit.

I have different prototyping methods for different applications. Sometimes you just have a vague idea and you just want to play with some parts. Soldering a circuit together seems like a waste of time if you know that you are going to be changing most of the parts before you are done, and many of them will get changed more than once. For those projects I use the "Tubelab". The first photo shows a prototype 6AV5 screen drive amp built in the Tubelab.

The Tubelab

The first generation Tubelab wasn't much more than some tube sockets screwed to a piece of plywood with a lot of clip leads to connect things up.

The second generation added a copper screen to the plywood to act as a ground plane. It also used individual "modules" which were PC boards with one or two tube sockets and a bunch of Fahnestock clips for the components. It was used to design the Tubelab SE amp. It was too big and took up most of my workbench, but did the job.

The third generation Tubelab used nylon pegboard for the base and the individual modules. There is still a copper screen under the base. "Euro barrier strips" are used for the interconnections and components. It is much smaller.

Personally I've never used these but they look like a good idea
http://www.tubesandmore.com/scripts/...02_EPOXYBOARDS

There are other times when the topology of the circuit, or at least the number of tubes and their types are known. The pre made turret boards in the link above allow for rapid prototyping, and can be used in the final amp if desired.

I have used them in situations where the circuitry is known, so the components are tacked on to the sockets and turrets. The second photo shows a prototype driver board being designed.

I have also used them where I had no clue what I was doing, but an amp was born anyway. The third photo shows two 6LR8's on the turret board, a Simple SE board, and about a million clip leads. I know that this isn't supposed to work, but it did!

[Loren42]

Originally Posted by tubelab.com

I have been prototyping circuits for nearly 50 years. Of course my abilities have improved a bit.

I have different prototyping methods for different applications. Sometimes you just have a vague idea and you just want to play with some parts. Soldering a circuit together seems like a waste of time if you know that you are going to be changing most of the parts before you are done, and many of them will get changed more than once. For those projects I use the "Tubelab". The first photo shows a prototype 6AV5 screen drive amp built in the Tubelab.

The Tubelab

The first generation Tubelab wasn't much more than some tube sockets screwed to a piece of plywood with a lot of clip leads to connect things up.

The second generation added a copper screen to the plywood to act as a ground plane. It also used individual "modules" which were PC boards with one or two tube sockets and a bunch of Fahnestock clips for the components. It was used to design the Tubelab SE amp. It was too big and took up most of my workbench, but did the job.

The third generation Tubelab used nylon pegboard for the base and the individual modules. There is still a copper screen under the base. "Euro barrier strips" are used for the interconnections and components. It is much smaller.



There are other times when the topology of the circuit, or at least the number of tubes and their types are known. The pre made turret boards in the link above allow for rapid prototyping, and can be used in the final amp if desired.

I have used them in situations where the circuitry is known, so the components are tacked on to the sockets and turrets. The second photo shows a prototype driver board being designed.

I have also used them where I had no clue what I was doing, but an amp was born anyway. The third photo shows two 6LR8's on the turret board, a Simple SE board, and about a million clip leads. I know that this isn't supposed to work, but it did!

Great idea and execution.

[pjanda1]

Originally Posted by tubelab.com

The third generation Tubelab used nylon pegboard for the base and the individual modules. There is still a copper screen under the base. "Euro barrier strips" are used for the interconnections and components. It is much smaller.

That thing is very cool. A simple, elegant solution.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers