You can also turn the uTracer into a transistor curve tracer:
https://www.dos4ever.com/uTracerNotebook/Notebook.html#tortester1 , I
haven't done it but thought about it a few times.
There's also the new uTracer V6, not a kit yet but it has a weblog:
I had a 575 - two, actually; it's quite a chunk of gear, weighing in at 70
pounds, with 39 vacuum tubes plus the CRT. I picked them up at an auction,
fiddled with them a bit, and decided I had other better uses for the space.
But a transistor curve tracer would still be a handy thing, and on
It should be easy to convert the 575 back into a tube curve tracer since it
was a modified 570 with the filament transformer removed and the sockets
changed. If you can find a meterless Hickok tube tester, you have the
sockets, switches and filament transformer you would need to convert it
As much as I would love to have my own curve-tracer, I have to be
practical. The transistors I select have SPICE models, so I simulate
everything in detail.
Nixie tubes, especially the rare or expensive ones like b7071 and R|Z568 ,
I generate I-V curves by hand for each segment/cathode. A
I have a couple of 575 that I might sell, either as is, or reconditioned
and calibrated (not inexpensive), with an operators manual. I also have
the 575 mod 122C which sports a 400V collector sweep power supply. The
audio people are crazy over them because they can be converted for TUBE
curve
You might have to settle for one of the more modern transistorized curve
tracers. In the last century when 500-series scopes were going for
$20-$50, I remember talking to someone at one of the ham swaps. He said
that they were being bought up and cannibalized by the audiophools because
they
When I was in high school, I got to use a Tek 575 curve tracer. Perfect
instrument to nail-down any differences between these devices.
Every now and then, I take a look on Ebay and ask myself if I should buy
one. Yikes...I just took a peek and there are several available.
Fortunately I just
Sure, but based on the similarities in the Central Semi data sheets, the
same die appears to be used interchangeably. So the factors I can imagine
is that they select and direct the leakier parts to the TO-220 package, or
that the TO-220 package makes a difference (like allowing a higher
It's the leakage (Icbo) that is 1000x greater in the MJE device, not the
current gain. There are many factors affecting leakage and current gain:
- Some are environmental (temperature, reverse-voltage, operating
current)
- Some are device construction (physical dimensions of base width
Is there a 1000X difference in the gain? Across all lots and all operating
conditions, I would have expected less than 10X.
On Thursday, April 23, 2020 at 3:56:44 PM UTC-7, gregebert wrote:
>
> Much of the additional leakage current is caused by the higher DC gain of
> the MJE device; the
Much of the additional leakage current is caused by the higher DC gain of
the MJE device; the datasheet says gain peaks around 240.
Basically, the reverse-leakage current from the collector-base junction
gets amplified by the DC gain (beta), to produce the overall leakage (Icbo)
--
You
The data differs though I just read that, missed it at the first
look.
/Martin
On Friday, 24 April 2020 00:32:28 UTC+2, Dekatron42 wrote:
>
> Central Semiconductor Corp list them as having the same die size, check
> their documents named "Device datasheet" here
>
On Thursday, April 23, 2020 at 3:10:36 PM UTC-7, gregebert wrote:
> I'm absolutely certain the MJE die is physically larger. For one thing,
it must conduct more thermal energy to the case.
I am inclined to agree, but if it were me, I would be willing to invest
$1.08 and a half hour in the
Central Semiconductor Corp list them as having the same die size, check
their documents named "Device datasheet" here
https://my.centralsemi.com/product/partpage2.php?part=CP310-MPSA42 and here
https://my.centralsemi.com/product/partpage2.php?part=CP310-MJE340, now I
don't know if other
I'm absolutely certain the MJE die is physically larger. For one thing, it
must conduct more thermal energy to the case.
Another tip-off is the difference in DC current-gain, and that in-turn
accounts for part of the 1000x difference in leakage current.
I believe leakage current is directly
So this is a matter of academic curiosity and not an effort to make your
device work. I think this is a neat thing to do. Based on your
observations, this suggests some experiments.
In a previous post, I speculated that both part numbers might use the same
chip. I now think this is
There are thermal considerations; the MJE340 is designed to be used on a
heat sink and is rated for 20W, vs 1.5W for the MPSA42.
Also, there are some differences in the safe operating area curves; the
MJE340 can tolerate a bit more current at any given voltage.
MJE device also has a lower Vce
: Mac Doktor
Sent: Wednesday, April 22, 2020 9:16 PM
To: neonixie-l
Subject: Re: [neonixie-l] MPSA42 or MJE340?
On Apr 22, 2020, at 9:03 PM, 'jf...@my-deja.com' via neonixie-l
wrote:
What do you have against the MJE340?
Me? Nothing. All of the IN-9 projects that I've seen online use
> On Apr 22, 2020, at 9:03 PM, 'jf...@my-deja.com' via neonixie-l
> wrote:
>
> What do you have against the MJE340?
Me? Nothing. All of the IN-9 projects that I've seen online use the MJE340.
I'm a duffer and I'm here to learn. Paul wanted everyone to pile on so have at
it! I'd be glad to
What do you have against the MJE340? Is it too large? Is it too much more
money (onesies retail in Silicon Valley is 34 cents versus 75 cents)? If I
had to go out and buy new parts in hobby quantities, I would get the MJE340
and not invest any more brain power, but if it was going to be used
Both transistors are rated for 500mA, so I don’t see why you need a MJE340 for
an IN-9. This is particularly relevant for me as I want to switch around 50mA
using 3.3V. Not sure what the voltage is right now, given that this is the
cathode.
> On Apr 22, 2020, at 5:25 PM, Mac Doktor wrote:
>
On Apr 22, 2020, at 9:39 AM, 'jf...@my-deja.com' via neonixie-l
wrote:
>
> I would say whichever is cheaper, keeping in mind that nothing is cheaper
> than free from the junque box. I used the floor sweepings (advertised as
> npn 300V and 10W) from Poly Paks, and none of these have failed
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