OT: topic...

[Rich S]

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

 

[John Larkin]

On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
<richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[John Robertson]

On 2021/11/23 12:15 p.m., John Larkin wrote:

On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.

So they feed the lunatic fringe instead?

The trolls are killing interest in this group, and the group is helping
them by responding to - The Marching Morons.

John :-#(#

 

[John Larkin]

On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <spam@flippers.com>
wrote:

On 2021/11/23 12:15 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.


So they feed the lunatic fringe instead?

The trolls are killing interest in this group, and the group is helping
them by responding to - The Marching Morons.

John :-#(#

OK, post some interesting electronics, preferably something specific.
A few real EEs show up here occasionally and might have something
intelligent to say.

But yes, the less on-topic and the more stupid the thread, the longer
it is.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[John Robertson]

On 2021/11/23 2:44 p.m., John Larkin wrote:

On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <spam@flippers.com
wrote:


On 2021/11/23 12:15 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.


So they feed the lunatic fringe instead?

The trolls are killing interest in this group, and the group is helping
them by responding to - The Marching Morons.

John :-#(#

OK, post some interesting electronics, preferably something specific.
A few real EEs show up here occasionally and might have something
intelligent to say.

But yes, the less on-topic and the more stupid the thread, the longer
it is.

I don\'t do what most of you folks consider that interesting electronics.
Most of my work is trying to save obsolete games using 1970s 8-bit CPUs.
I design a few boards, have a friend or two make others that are deeper
in FPGA than I can go (no time or skill), but I try to have some fun
with it all.

For example, one problem I am looking for a solution is trying to read
old single CHIP CPUs such as the Signetics/Philips MAB84XX series of
chips. I know the ROM is embedded in the chip and can\'t normally be
gotten at, I\'m thinking thought that there is a rare document floating
around that would show how to verify the ROM/RAM code by sending some
signal in the T (est) pin-Input pin, testable using the JT1 or JNT1
instructions, whatever those are! Not covered in any documents I\'ve
found so far though. I\'ve found these so far which aren\'t bad:

https://www.flippers.com/pdfs/MAB84XX_Signetics.pdf

https://www.flippers.com/pdfs/MAB84X1_MAF84X1_MAF84AX1_Family.pdf

Other 8-bit MPUs had such tests so you could cycle the data out to make
sure the chip is good, why not this one?

Like I say, fun, but not very modern tech...

John :-#)#

 

[Phil Hobbs]

John Robertson wrote:

On 2021/11/23 2:44 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <spam@flippers.com
wrote:


On 2021/11/23 12:15 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.


So they feed the lunatic fringe instead?

The trolls are killing interest in this group, and the group is helping
them by responding to - The Marching Morons.

John :-#(#

OK, post some interesting electronics, preferably something specific.
A few real EEs show up here occasionally and might have something
intelligent to say.

But yes, the less on-topic and the more stupid the thread, the longer
it is.


I don\'t do what most of you folks consider that interesting electronics.
Most of my work is trying to save obsolete games using 1970s 8-bit CPUs.

That\'s interesting to me, for one.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[bitrex]

On 11/23/2021 5:44 PM, John Larkin wrote:

On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <spam@flippers.com
wrote:


On 2021/11/23 12:15 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.


So they feed the lunatic fringe instead?

The trolls are killing interest in this group, and the group is helping
them by responding to - The Marching Morons.

John :-#(#

OK, post some interesting electronics, preferably something specific.
A few real EEs show up here occasionally and might have something
intelligent to say.

But yes, the less on-topic and the more stupid the thread, the longer
it is.

Here\'s a thing, it\'s a type of Cuk converter. If you just replace the
top FET with the PMOS to avoid a high-side driver, and try to run it
with no dead time it\'s ugly, the body diodes face the wrong way to allow
the two FETs to switch off simultaneously gracefully and the diode & LC
network rings and rings.

Cross coupling a bit of feedback from the inductors to the FET gates
seems to clean it up. 5 volts to about -135 with a more reasonable 85%
duty cycle than the 95%+ a boost would need, the efficiency of a boost
with that high a ratio would probably stink, this one seems pretty good.
But it would need custom inductors I think so I can\'t immediately think
of a use for it

Version 4
SHEET 1 2392 1316
WIRE 128 -768 -576 -768
WIRE 448 -768 128 -768
WIRE 672 -768 448 -768
WIRE 128 -624 128 -768
WIRE 448 -624 448 -768
WIRE 672 -400 672 -768
WIRE 224 -384 -352 -384
WIRE 448 -384 448 -544
WIRE 448 -384 304 -384
WIRE 512 -384 448 -384
WIRE 624 -384 576 -384
WIRE 128 -208 128 -544
WIRE 864 -208 128 -208
WIRE 1088 -208 864 -208
WIRE 1376 -208 1152 -208
WIRE 1552 -208 1376 -208
WIRE 1872 -208 1632 -208
WIRE 2176 -208 1872 -208
WIRE 2272 -208 2176 -208
WIRE -352 -80 -352 -384
WIRE 864 -64 864 -208
WIRE 1376 -48 1376 -208
WIRE 1376 16 1376 0
WIRE 2176 64 2176 -208
WIRE -576 80 -576 -768
WIRE 864 80 864 0
WIRE 1376 80 1376 16
WIRE 1872 80 1872 -208
WIRE 128 288 128 -208
WIRE -352 368 -352 -16
WIRE -256 368 -352 368
WIRE -112 368 -176 368
WIRE -32 368 -112 368
WIRE 80 368 32 368
WIRE 672 368 672 -304
WIRE 864 368 1376 80
WIRE 864 368 672 368
WIRE 1104 368 864 368
WIRE 1392 368 864 80
WIRE 1392 368 1168 368
WIRE 1872 368 1872 144
WIRE 1872 368 1392 368
WIRE 2176 368 2176 144
WIRE 2176 368 1872 368
WIRE 2256 368 2176 368
WIRE 2176 480 2176 368
WIRE -112 512 -112 368
WIRE 672 608 672 368
WIRE 2176 624 2176 560
WIRE -576 800 -576 160
WIRE -112 800 -112 592
WIRE -112 800 -576 800
WIRE 128 800 128 384
WIRE 128 800 -112 800
WIRE 576 800 128 800
WIRE 672 800 672 688
WIRE 672 800 576 800
WIRE 576 848 576 800
WIRE -352 912 -352 368
WIRE -352 1296 -352 992
FLAG 576 848 0
FLAG -352 1296 0
FLAG 2176 624 0
FLAG 2272 -208 Out-
IOPIN 2272 -208 Out
FLAG 2256 368 Out+
IOPIN 2256 368 Out
SYMBOL voltage -576 64 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL nmos 80 288 R0
SYMATTR InstName M1
SYMATTR Value Si3440DV
SYMBOL cap 1152 -224 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 40 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 0.47µ
SYMBOL cap 1168 352 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 0.47µ
SYMBOL schottky 1360 -48 R0
SYMATTR InstName D1
SYMATTR Value RB238T150
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL ind2 1536 -192 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 4 56 VBottom 2
SYMATTR InstName L3
SYMATTR Value 220µ
SYMBOL schottky 848 -64 R0
SYMATTR InstName D2
SYMATTR Value RB238T150
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL voltage -352 896 R0
WINDOW 3 52 50 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 5 0 10n 10n 0.0000122 0.0000142)
SYMATTR InstName V2
SYMBOL cap 1856 80 R0
SYMATTR InstName C4
SYMATTR Value 4.7µ
SYMBOL ind2 144 -528 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L1
SYMATTR Value 220µ
SYMBOL ind2 688 704 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L2
SYMATTR Value 220µ
SYMBOL res 2160 464 R0
SYMATTR InstName R1
SYMATTR Value 1Meg
SYMBOL Digital\\\\inv -416 -16 R270
SYMATTR InstName A1
SYMATTR SpiceLine Vhigh=5V,Td=5e-9,Trise=100n
SYMBOL pmos 624 -304 M180
SYMATTR InstName M2
SYMATTR Value QS8M51_P
SYMBOL ind2 208 -368 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 4 56 VBottom 2
SYMATTR InstName L6
SYMATTR Value 2.2µ
SYMBOL ind2 -272 384 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 4 56 VBottom 2
SYMATTR InstName L7
SYMATTR Value 2.2µ
SYMBOL res -128 496 R0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL res 432 -640 R0
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL FerriteBead 544 -384 R90
WINDOW 0 -16 0 VBottom 2
SYMATTR InstName L4
SYMATTR Value 3.2n
SYMATTR SpiceLine Ipk=2 Rser=0.064 Rpar=620 Cpar=1.1p mfg=\"Würth
Elektronik\" pn=\"782763621 WE-CBA 1206\"
SYMBOL FerriteBead 0 368 R90
WINDOW 0 -16 0 VBottom 2
SYMATTR InstName L5
SYMATTR Value 3.2n
SYMATTR SpiceLine Ipk=2 Rser=0.064 Rpar=620 Cpar=1.1p mfg=\"Würth
Elektronik\" pn=\"782763621 WE-CBA 1206\"
SYMBOL res 2160 48 R0
SYMATTR InstName Rload1
SYMATTR Value 10k
TEXT -760 560 Left 2 !.tran 0.1
TEXT 200 -568 Left 2 !K1 L1 L6 0.99
TEXT 256 464 Left 2 !K2 L7 L2 0.99

 

[John S]

On 11/23/2021 1:58 PM, Rich S wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Would Dr. Carl Sagan testifying before congress in 1985 about greenhouse
gasses and climate change be too far off-topic?

 

[Anthony William Sloman]

On Wednesday, November 24, 2021 at 7:16:07 AM UTC+11, John Larkin wrote:

On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsuli...@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic topics in this group?

can we get on topic, and save the off-topic stuff in another group?

This group has survived and is pretty active - we may be doing something right. Off=topic gossip may be what\'s keeping people involved between real electronic design threads.

> Not many people actually do electronic design, and the ones who do are reluctant to show what they are doing in any detail.

That\'s John Larkin to a tee. He develops quite a lot of electronics, but doesn\'t seem to design any of it. When he does show what he is doing in any detail, people suggest changes that might make it work better, and he doesn\'t seem to like thinking about that.

There isn\'t all that much design discussion here, and he doesn\'t take part in any of it.

--
Bill Sloman, Sydney

 

[Anthony William Sloman]

On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:

On 11/23/2021 5:44 PM, John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com
wrote:

<snipped the .asc file>

https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf

says that the transistor can\'t take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn\'t be that difficult to protect the junction, but it\'s not a great example of careful design.

--
Bill Sloman, Sydney

 

[Jan Panteltje]

On a sunny day (Tue, 23 Nov 2021 11:58:55 -0800 (PST)) it happened Rich S
<richsulinengineer@gmail.com> wrote in
<a3a7511b-3ad4-4ae1-96b0-51b7c2f5acb6n@googlegroups.com>:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

China agent man wrote \"stop insulting Chinese leader.\"

This is Usenet get Used to it
Its a free world.

One of the last possibly
before you get jabbed and chipped and controlled by Big Brothel.

You posting had no electronic content, complainer.

 

[Jan Panteltje]

On a sunny day (Tue, 23 Nov 2021 16:11:13 -0800) it happened John Robertson
<spam@flippers.com> wrote in <kYOdnS1cYIW_HgD8nZ2dnUU7-eXNnZ2d@giganews.com>:

On 2021/11/23 2:44 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <spam@flippers.com
wrote:


On 2021/11/23 12:15 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.


So they feed the lunatic fringe instead?

The trolls are killing interest in this group, and the group is helping
them by responding to - The Marching Morons.

John :-#(#

OK, post some interesting electronics, preferably something specific.
A few real EEs show up here occasionally and might have something
intelligent to say.

But yes, the less on-topic and the more stupid the thread, the longer
it is.


I don\'t do what most of you folks consider that interesting electronics.
Most of my work is trying to save obsolete games using 1970s 8-bit CPUs.
I design a few boards, have a friend or two make others that are deeper
in FPGA than I can go (no time or skill), but I try to have some fun
with it all.

For example, one problem I am looking for a solution is trying to read
old single CHIP CPUs such as the Signetics/Philips MAB84XX series of
chips. I know the ROM is embedded in the chip and can\'t normally be
gotten at, I\'m thinking thought that there is a rare document floating
around that would show how to verify the ROM/RAM code by sending some
signal in the T (est) pin-Input pin, testable using the JT1 or JNT1
instructions, whatever those are! Not covered in any documents I\'ve
found so far though. I\'ve found these so far which aren\'t bad:

https://www.flippers.com/pdfs/MAB84XX_Signetics.pdf

https://www.flippers.com/pdfs/MAB84X1_MAF84X1_MAF84AX1_Family.pdf

Other 8-bit MPUs had such tests so you could cycle the data out to make
sure the chip is good, why not this one?

Like I say, fun, but not very modern tech...

John :-#)#

In the long ago days there was much in hacker grousp like alt.satellite.tv.europe
I think it was, about hacking smartcards (especially with PIC micros)
Power supply variations and other tricks to make it list ROM / FLASH content etc.
Many papers were on the internet from very high tech like opening the chip
and probing the SillyCon to relative simple solutions.
I admit to playing with it
Not sure how much is preserved, google.

 

[Jan Panteltje]

On a sunny day (Tue, 23 Nov 2021 16:11:13 -0800) it happened John Robertson
<spam@flippers.com> wrote in <kYOdnS1cYIW_HgD8nZ2dnUU7-eXNnZ2d@giganews.com>:

On 2021/11/23 2:44 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <spam@flippers.com
wrote:


On 2021/11/23 12:15 p.m., John Larkin wrote:
On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.


So they feed the lunatic fringe instead?

The trolls are killing interest in this group, and the group is helping
them by responding to - The Marching Morons.

John :-#(#

OK, post some interesting electronics, preferably something specific.
A few real EEs show up here occasionally and might have something
intelligent to say.

But yes, the less on-topic and the more stupid the thread, the longer
it is.


I don\'t do what most of you folks consider that interesting electronics.
Most of my work is trying to save obsolete games using 1970s 8-bit CPUs.
I design a few boards, have a friend or two make others that are deeper
in FPGA than I can go (no time or skill), but I try to have some fun
with it all.

For example, one problem I am looking for a solution is trying to read
old single CHIP CPUs such as the Signetics/Philips MAB84XX series of
chips. I know the ROM is embedded in the chip and can\'t normally be
gotten at, I\'m thinking thought that there is a rare document floating
around that would show how to verify the ROM/RAM code by sending some
signal in the T (est) pin-Input pin, testable using the JT1 or JNT1
instructions, whatever those are! Not covered in any documents I\'ve
found so far though. I\'ve found these so far which aren\'t bad:

https://www.flippers.com/pdfs/MAB84XX_Signetics.pdf

https://www.flippers.com/pdfs/MAB84X1_MAF84X1_MAF84AX1_Family.pdf

Other 8-bit MPUs had such tests so you could cycle the data out to make
sure the chip is good, why not this one?

Like I say, fun, but not very modern tech...

John :-#)#

In the long ago days there was much in hacker grousp like alt.satellite.tv.europe
I think it was, about hacking smartcards (especially with PIC micros)
Power supply variations and other tricks to make it list ROM / FLASH content etc.
Many papers were on the internet from very high tech like opening the chip
and probing the SillyCon to relative simple solutions.
I admit to playing with it
Not sure how much is preserved, google.

 

[bitrex]

On 11/24/2021 1:18 AM, Anthony William Sloman wrote:

On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
On 11/23/2021 5:44 PM, John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com
wrote:

snipped the .asc file

https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf

says that the transistor can\'t take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn\'t be that difficult to protect the junction, but it\'s not a great example of careful design.

Eh? There\'s no BJTs in that circuit my good man, at least there
shouldn\'t be. You sure you responding to the right circuit?

 

[bitrex]

On 11/24/2021 1:18 AM, Anthony William Sloman wrote:

On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
On 11/23/2021 5:44 PM, John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com
wrote:

snipped the .asc file

https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf

says that the transistor can\'t take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn\'t be that difficult to protect the junction, but it\'s not a great example of careful design.

Whatchoo talkin bout, Willis

<https://www.youtube.com/watch?v=JfpkObkgEEM>

 

[Anthony William Sloman]

On Thursday, November 25, 2021 at 1:23:06 AM UTC+11, bitrex wrote:

On 11/24/2021 1:18 AM, Anthony William Sloman wrote:
On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
On 11/23/2021 5:44 PM, John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com
wrote:

snipped the .asc file

https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf

says that the transistor can\'t take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn\'t be that difficult to protect the junction, but it\'s not a great example of careful design.

Eh? There\'s no BJTs in that circuit my good man, at least there
shouldn\'t be. You sure you responding to the right circuit?

I thought I\'d picked it out of this thread, but the route through Notepad to the .asc file seems to have gotten messed up. There doesn\'t seem to be a Q1 or a 2SCR552 in your text.

A second attempt didn\'t go well, so I\'ve got to say, oops - sorry. I\'m not quite sure how I got it wrong and it may take me a while to find out.

--
Bill Sloman, Sydney

 

[Tom Del Rosso]

John Larkin wrote:

On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.

The majority of threads are on-topic, but they usually don\'t require
many posts to solve the issue.


--
Defund the Thought Police

 

[Rich S]

On Thursday, November 25, 2021 at 8:48:03 AM UTC, Tom Del Rosso wrote:

John Larkin wrote:
On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
richsuli...@gmail.com> wrote:

the topic is \"off topic\"

why do we have so many off-topic
topics in this group?

can we get on topic, and save the
off-topic stuff in another group?

= RS

Not many people actually do electronic design, and the ones who do are
reluctant to show what they are doing in any detail.
The majority of threads are on-topic, but they usually don\'t require
many posts to solve the issue.


--
Defund the Thought Police

Indeed, Tom, probably often correct.
The on topic threads are resolvable (not so subjective,
not generally inflammatory).

It seems /some/ of us revel in the knee-jerk emotional
responses, jabe your fellow s-e-d poster, pulling people\'s
chain, stoking the fires, etc.
I never suggested we could ban all things off-topic.

I just wanted us to pause & think about it, at least.

And, it\'s good; I see some good points.

Maybe this group is mis-named. The world of
electronic engineering is more than \"design\".

Maybe the amount of design posted here really
reflects reality? --there isn\'t That Much new design work
taking place? Most things are re-hashes of standard
designs?

This audience is doing many other things
aside from pure design work. Still electronic-related.
And challenging.

thanks = RS

 

[Anthony William Sloman]

On Thursday, November 25, 2021 at 2:52:29 PM UTC+11, Anthony William Sloman wrote:

On Thursday, November 25, 2021 at 1:23:06 AM UTC+11, bitrex wrote:
On 11/24/2021 1:18 AM, Anthony William Sloman wrote:
On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
On 11/23/2021 5:44 PM, John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com
wrote:

snipped the .asc file

https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf

says that the transistor can\'t take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn\'t be that difficult to protect the junction, but it\'s not a great example of careful design.

Eh? There\'s no BJTs in that circuit my good man, at least there
shouldn\'t be. You sure you responding to the right circuit?
I thought I\'d picked it out of this thread, but the route through Notepad to the .asc file seems to have gotten messed up. There doesn\'t seem to be a Q1 or a 2SCR552 in your text.

A second attempt didn\'t go well, so I\'ve got to say, oops - sorry. I\'m not quite sure how I got it wrong and it may take me a while to find out.

A third attempt went better. The circuit looks much more like what you were describing. It isn\'t obvious what it is supposed to do.

I had to move a couple of resistors a bit to make them them sit on the wires that were obviously intended to connect them

Vout+ sits at about 73V for about 13usec then drops to about -1V for about 1 usec. Vout- sits about -56V for the same 13usec and drops to -130V for the same 1usec.

Is this what you intended? What was the intended application?

Bill Sloman, Sydney

 

[bitrex]

On 11/27/2021 8:14 AM, Anthony William Sloman wrote:

On Thursday, November 25, 2021 at 2:52:29 PM UTC+11, Anthony William Sloman wrote:
On Thursday, November 25, 2021 at 1:23:06 AM UTC+11, bitrex wrote:
On 11/24/2021 1:18 AM, Anthony William Sloman wrote:
On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
On 11/23/2021 5:44 PM, John Larkin wrote:
On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com
wrote:

snipped the .asc file

https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf

says that the transistor can\'t take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn\'t be that difficult to protect the junction, but it\'s not a great example of careful design.

Eh? There\'s no BJTs in that circuit my good man, at least there
shouldn\'t be. You sure you responding to the right circuit?
I thought I\'d picked it out of this thread, but the route through Notepad to the .asc file seems to have gotten messed up. There doesn\'t seem to be a Q1 or a 2SCR552 in your text.

A second attempt didn\'t go well, so I\'ve got to say, oops - sorry. I\'m not quite sure how I got it wrong and it may take me a while to find out.

A third attempt went better. The circuit looks much more like what you were describing. It isn\'t obvious what it is supposed to do.

I had to move a couple of resistors a bit to make them them sit on the wires that were obviously intended to connect them

Vout+ sits at about 73V for about 13usec then drops to about -1V for about 1 usec. Vout- sits about -56V for the same 13usec and drops to -130V for the same 1usec.

Is this what you intended? What was the intended application?

Bill Sloman, Sydney

Measure across the terminals, the output is floating wrt ground.