Tube design testbed
 

As you may know from posts I made a few months back (before I moved
house) I have been doing some work on using 6AU6 tubes in triode mode
for preamps. The set up I have at the moment is pretty crude. I stripped
a chassis from an old battery valve radio, wired in the components I
needed then bolted it to a piece of wood along with the mains
transformer and PSU components. This is OK as far as it goes but apart
from looking tatty it is not very easy to make circuit changes but, as I
am making noise measurements, layout is crucial.

So.... I was wondering if anyone makes something I could use as the
basis of my experiments that would be easier to modify?

Any ideas?

Cheers

Ian

Tube design testbed
 

On Sat, 03 Nov 2007 14:31:08 +0000, Ian Thompson-Bell
wrote:

As you may know from posts I made a few months back (before I moved
house) I have been doing some work on using 6AU6 tubes in triode mode
for preamps. The set up I have at the moment is pretty crude. I stripped
a chassis from an old battery valve radio, wired in the components I
needed then bolted it to a piece of wood along with the mains
transformer and PSU components. This is OK as far as it goes but apart
from looking tatty it is not very easy to make circuit changes but, as I
am making noise measurements, layout is crucial.

So.... I was wondering if anyone makes something I could use as the
basis of my experiments that would be easier to modify?

Any ideas?

The piece of wood is actually a pretty good idea, as it allows you to
manage your grounds properly, something it is much harder to do when
everything is bolted to a chassis.

Layout doesn't do much for noise, per se, but it will greatly affect
hum. Do all the usual things with extra big caps in the power supply
and battery powered heaters. But mainly be very assiduous in
star-point-grounding every signal component and lead around the valve
you are measuring.

You will probably try half a dozen layouts before you convince
yourself you are measuring what you actually want to measure, and not
some spurious effect.

To make component changes easier, cut a nearly chassis-sized hole
through the wood so you don't need to unbolt everything to make a
change.

d

--
Pearce Consulting
http://www.pearce.uk.com

Tube design testbed
 

Don Pearce wrote:
On Sat, 03 Nov 2007 14:31:08 +0000, Ian Thompson-Bell
wrote:

As you may know from posts I made a few months back (before I moved
house) I have been doing some work on using 6AU6 tubes in triode mode
for preamps. The set up I have at the moment is pretty crude. I stripped
a chassis from an old battery valve radio, wired in the components I
needed then bolted it to a piece of wood along with the mains
transformer and PSU components. This is OK as far as it goes but apart
from looking tatty it is not very easy to make circuit changes but, as I
am making noise measurements, layout is crucial.

So.... I was wondering if anyone makes something I could use as the
basis of my experiments that would be easier to modify?

Any ideas?

The piece of wood is actually a pretty good idea, as it allows you to
manage your grounds properly, something it is much harder to do when
everything is bolted to a chassis.

Layout doesn't do much for noise, per se, but it will greatly affect
hum. Do all the usual things with extra big caps in the power supply
and battery powered heaters. But mainly be very assiduous in
star-point-grounding every signal component and lead around the valve
you are measuring.

You will probably try half a dozen layouts before you convince
yourself you are measuring what you actually want to measure, and not
some spurious effect.

To make component changes easier, cut a nearly chassis-sized hole
through the wood so you don't need to unbolt everything to make a
change.

d


Thanks for the input Don. I have used wood as a breadboard many times in
the past - it is pretty good for keeping everything together. Hum is not
a problem as I soon discovered a battery heater supply was these easiest
way to eliminate it. Component change is the real issue. The chassis is
basically U shaped so I might try removing one side to make it L shaped
which should ease access.

Cheers

ian

Tube design testbed
 

Ian Thompson-Bell wrote:
Don Pearce wrote:
On Sat, 03 Nov 2007 14:31:08 +0000, Ian Thompson-Bell
wrote:

As you may know from posts I made a few months back (before I moved
house) I have been doing some work on using 6AU6 tubes in triode mode
for preamps. The set up I have at the moment is pretty crude. I
stripped a chassis from an old battery valve radio, wired in the
components I needed then bolted it to a piece of wood along with the
mains transformer and PSU components. This is OK as far as it goes
but apart from looking tatty it is not very easy to make circuit
changes but, as I am making noise measurements, layout is crucial.

So.... I was wondering if anyone makes something I could use as the
basis of my experiments that would be easier to modify?

Any ideas?

The piece of wood is actually a pretty good idea, as it allows you to
manage your grounds properly, something it is much harder to do when
everything is bolted to a chassis.

Layout doesn't do much for noise, per se, but it will greatly affect
hum. Do all the usual things with extra big caps in the power supply
and battery powered heaters. But mainly be very assiduous in
star-point-grounding every signal component and lead around the valve
you are measuring.

You will probably try half a dozen layouts before you convince
yourself you are measuring what you actually want to measure, and not
some spurious effect.

To make component changes easier, cut a nearly chassis-sized hole
through the wood so you don't need to unbolt everything to make a
change.

d


Thanks for the input Don. I have used wood as a breadboard many times in
the past - it is pretty good for keeping everything together. Hum is not
a problem as I soon discovered a battery heater supply was these easiest
way to eliminate it. Component change is the real issue. The chassis is
basically U shaped so I might try removing one side to make it L shaped
which should ease access.

Cheers

ian

Just treated myself to a pair of tin snips. I removed one side of the
chassis, laid it on its side so the valve bases are facing me and
screwed it to the wood. Much better.

Cheers

ian

Tube design testbed
 

They call it breadboarding because in the tube days an actual bread
board was used. It still works very well.

Tube design testbed
 

Bret Ludwig wrote:
They call it breadboarding because in the tube days an actual bread
board was used. It still works very well.


I remember when I first got into transistors in the 60s that Practical
Wireless in the UK had a series of articles for transistor based
receivers that were built on a piece of wooud. You used wood screws with
copper washers to connect things together. worked great.

Ian

Tube design testbed
 

"Ian Thompson-Bell" wrote in message
...
Bret Ludwig wrote:
They call it breadboarding because in the tube days an actual bread
board was used. It still works very well.


I remember when I first got into transistors in the 60s that Practical
Wireless in the UK had a series of articles for transistor based receivers
that were built on a piece of wooud. You used wood screws with copper
washers to connect things together. worked great.

Ian

I recently made myself a breadboard from, would you believe, a breadboard. I
stuck in three rows of nails and stretched three rows of tinned copper wire
to make the +- and ground rails, and it's really useful to build up
circuits. I used to do this in the early '70s, then we went all sexy with
the plug-in plastic sort of "prototype panels". Can't beat a breadboard for
simplicity.

S.



--
http://audiopages.googlepages.com

Tube design testbed
 

"Ian Thompson-Bell" wrote
I remember when I first got into transistors in the 60s that Practical Wireless in the UK had a series of articles for
transistor based receivers that were built on a piece of wooud. You used wood screws with copper washers to connect things
together. worked great.

Ian

Indeed so. When I was _very_ young (maybe 9 or 10), my first
electronics book was (literally and honestly) a LADYBIRD book,
written by some Rev. (spit) someone-or-other, IIRC. Anyway, it
described various simple transistor circuits, for example,
an astable multivibrator "flip-flop", wherein 2 small MES bulbs
would flash on and off in opposition.

The circuits were suggested to be assembled on small wooden boards,
with those wood screws and screw-cap-things that go between the
screw head and the wood. I forget what they're called. Anyway,
I was lucky in that my Dad gave me a proper "modern" breadboard to use.

The transistors used in the book, and by me, were germanium PNP AC128 types.
With long bendy wires on them and a red dot to indicate the emitter
(again, IIRC). EBC.


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie

Tube design testbed
 

On Sat, 3 Nov 2007 20:08:43 -0000, "Fleetie"
wrote:

"Ian Thompson-Bell" wrote
I remember when I first got into transistors in the 60s that Practical Wireless in the UK had a series of articles for
transistor based receivers that were built on a piece of wooud. You used wood screws with copper washers to connect things
together. worked great.

Ian

Indeed so. When I was _very_ young (maybe 9 or 10), my first
electronics book was (literally and honestly) a LADYBIRD book,
written by some Rev. (spit) someone-or-other, IIRC. Anyway, it
described various simple transistor circuits, for example,
an astable multivibrator "flip-flop", wherein 2 small MES bulbs
would flash on and off in opposition.

The circuits were suggested to be assembled on small wooden boards,
with those wood screws and screw-cap-things that go between the
screw head and the wood. I forget what they're called. Anyway,
I was lucky in that my Dad gave me a proper "modern" breadboard to use.

The transistors used in the book, and by me, were germanium PNP AC128 types.
With long bendy wires on them and a red dot to indicate the emitter
(again, IIRC). EBC.


Very nearly - it was the collector back then. Were they the type with
clear gel filling that you could use as phototransistors if you
scraped the paint off?

d

--
Pearce Consulting
http://www.pearce.uk.com

Tube design testbed
 

Don Pearce wrote:
On Sat, 3 Nov 2007 20:08:43 -0000, "Fleetie"
wrote:

"Ian Thompson-Bell" wrote
I remember when I first got into transistors in the 60s that Practical Wireless in the UK had a series of articles for
transistor based receivers that were built on a piece of wooud. You used wood screws with copper washers to connect things
together. worked great.

Ian
Indeed so. When I was _very_ young (maybe 9 or 10), my first
electronics book was (literally and honestly) a LADYBIRD book,
written by some Rev. (spit) someone-or-other, IIRC. Anyway, it
described various simple transistor circuits, for example,
an astable multivibrator "flip-flop", wherein 2 small MES bulbs
would flash on and off in opposition.

The circuits were suggested to be assembled on small wooden boards,
with those wood screws and screw-cap-things that go between the
screw head and the wood. I forget what they're called. Anyway,
I was lucky in that my Dad gave me a proper "modern" breadboard to use.

The transistors used in the book, and by me, were germanium PNP AC128 types.
With long bendy wires on them and a red dot to indicate the emitter
(again, IIRC). EBC.


Very nearly - it was the collector back then. Were they the type with
clear gel filling that you could use as phototransistors if you
scraped the paint off?

d


IIRC types like the AC128 had metal cans. I think it was the good old
OC71 that you could scrape the paint off to make a photo-transitor -
that is until they started filling them with opaque gunk.

Spoilsports!

Ian