wart overvoltage protection...

J

John Larkin

Guest
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.

We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.

I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.

We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.

This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.

We once used a TI electronic fuse IC, but it liked to blow up.
 
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
> We make a gadget that\'s powered by a 12 volt wart, and sometimes auser applies 24 and blows one up.We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.It\'s posssible that most any useful polyfuse+TVS combo can be teasedto destruction.I think Phil H mentioned some gadget, a polyzorb or something, thatwould be better. I can\'t find it.We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCRcrowbar, or something.This is all entangled with parts availabity. Ideally the box wouldjust work from 12 or 24, but that has separate complications.We once used a TI electronic fuse IC, but it liked to blow up.

Have some series resistance to work at 24v, and switch the
resistance out if the voltage drops er stays under
13v?

Cheers
--


----Android NewsGroup Reader----
https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html
 
Martin Rid wrote:
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
We make a gadget that\'s powered by a 12 volt wart, and sometimes auser applies 24 and blows one up.We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.It\'s posssible that most any useful polyfuse+TVS combo can be teasedto destruction.I think Phil H mentioned some gadget, a polyzorb or something, thatwould be better. I can\'t find it.We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCRcrowbar, or something.This is all entangled with parts availabity. Ideally the box wouldjust work from 12 or 24, but that has separate complications.We once used a TI electronic fuse IC, but it liked to blow up.

Have some series resistance to work at 24v, and switch the
resistance out if the voltage drops er stays under
13v?

Cheers
Click to expand...

Tyco PolyZens were amazing, but unfortunately they were available for
only a few years. I think they had to have too many part numbers to
fill all the (current, voltage) space.

It was a pretty slick idea, laminating the TVS and polyswitch together
so that you couldn\'t fry the one without switching the other.

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
 
Martin Rid wrote:
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
We make a gadget that\'s powered by a 12 volt wart, and sometimes auser applies 24 and blows one up.We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.It\'s posssible that most any useful polyfuse+TVS combo can be teasedto destruction.I think Phil H mentioned some gadget, a polyzorb or something, thatwould be better. I can\'t find it.We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCRcrowbar, or something.This is all entangled with parts availabity. Ideally the box wouldjust work from 12 or 24, but that has separate complications.We once used a TI electronic fuse IC, but it liked to blow up.

Have some series resistance to work at 24v, and switch the
resistance out if the voltage drops er stays under
13v?

Cheers

Or maybe an LM393 and a PFET.
Click to expand...

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
 
On Fri, 30 Sep 2022 17:53:05 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

Martin Rid wrote:
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
We make a gadget that\'s powered by a 12 volt wart, and sometimes auser applies 24 and blows one up.We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.It\'s posssible that most any useful polyfuse+TVS combo can be teasedto destruction.I think Phil H mentioned some gadget, a polyzorb or something, thatwould be better. I can\'t find it.We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCRcrowbar, or something.This is all entangled with parts availabity. Ideally the box wouldjust work from 12 or 24, but that has separate complications.We once used a TI electronic fuse IC, but it liked to blow up.

Have some series resistance to work at 24v, and switch the
resistance out if the voltage drops er stays under
13v?

Cheers

Or maybe an LM393 and a PFET.

Cheers

Phil Hobbs
Click to expand...

That\'s an idea, a pfet current limiter that entirely shuts off if the
input goes above maybe 14 volts. At maybe a 500 mA, fet dissipation
would be OK.

Someone here suggested making our own polyzen sort of thing, but I
suspect we couldn\'t successfully transfer the heat from the TVS to the
polyfuse fast enough.

An SMB12A TVS is rated for peak power, 600 watts, but not rated for DC
power. 5 watts maybe with big pads?
 
John Larkin <jlarkin@highland_atwork_technology.com> wrote:

- OVP Protection
- no worst-case temp analysis done

Version 4
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--
MRM
 
On Friday, September 30, 2022 at 1:14:16 PM UTC-7, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
Click to expand...

So, is the power inlet clearly laser-burn-marked
as 12V center positive? And is the supplied power
brick similarly clearly labeled?
 
On Friday, September 30, 2022 at 4:14:16 PM UTC-4, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.

We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.

I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.

We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.

This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.

We once used a TI electronic fuse IC, but it liked to blow up.
Click to expand...

There are specialized OVP ICs for just this application, Maxim and ON make them, and they must be selling like hot cakes because availability is not obvious.

Mouser has this:
https://www.mouser.com/datasheet/2/936/KTS1662-04d-1634486.pdf

Never heard of Kinetic Technologies, do your own approval if you\'re interested. They\'re available and not too pricey at all, main thing is next to nothing external components required:
https://www.mouser.com/ProductDetail/Kinetic-Technologies/KTS1662EUW-TR?qs=lc2O%252BfHJPVZkAuNkM71H7w%3D%3D
It has the same features but with better performance than the ON and Maxim parts.
 
On a sunny day (Fri, 30 Sep 2022 13:14:03 -0700) it happened John Larkin
<jlarkin@highland_atwork_technology.com> wrote in
<5giejh5m7h4uqgifb89d8v54qsk0n4aifi@4ax.com>:

We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.

We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.

I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.

We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.

This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.

We once used a TI electronic fuse IC, but it liked to blow up.
Click to expand...

Better switcher regulator that accepts up to 24 V
 
John Larkin wrote:
On Fri, 30 Sep 2022 17:53:05 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

Martin Rid wrote:
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in
message:r
We make a gadget that\'s powered by a 12 volt wart, and
sometimes auser applies 24 and blows one up.We have a polyfuse
and a 12 volt TVS and they sometimes fry the TVS.It\'s posssible
that most any useful polyfuse+TVS combo can be teasedto
destruction.I think Phil H mentioned some gadget, a polyzorb or
something, thatwould be better. I can\'t find it.We might
fine-tune the polyfuse+TVS, or maybe go polyfuse and
SCRcrowbar, or something.This is all entangled with parts
availabity. Ideally the box wouldjust work from 12 or 24, but
that has separate complications.We once used a TI electronic
fuse IC, but it liked to blow up.

Have some series resistance to work at 24v, and switch the
resistance out if the voltage drops er stays under 13v?

Cheers

Or maybe an LM393 and a PFET.


That\'s an idea, a pfet current limiter that entirely shuts off if
the input goes above maybe 14 volts. At maybe a 500 mA, fet
dissipation would be OK.

Someone here suggested making our own polyzen sort of thing, but I
suspect we couldn\'t successfully transfer the heat from the TVS to
the polyfuse fast enough.

An SMB12A TVS is rated for peak power, 600 watts, but not rated for
DC power. 5 watts maybe with big pads?
Click to expand...

I\'ve occasionally looked at the specialized OVP/power limiter chips, but
they tend to cost $$$, and for my purposes they don\'t look as good as
doing the limiting locally. (If I were controlling big motors or
something, that might be a different matter.)

At various times I\'ve used LP2951s to make small amounts of +3.3V
directly from the wall wart to run startup circuitry and so forth. An
LM393 is a 358 with different metal--the input devices are lateral PNPs,
and so will take a lot of positive voltage regardless of the supplies.

A few microseconds of delay is no problem for that job.

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
 
Mike Monett VE3BTI <spamme@not.com> wrote:

XVII Version
- Replaced 1N759, 12V Zener, not available on XVII

Version 4
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--
MRM
 
On 01-Oct-22 6:14 am, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.

We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.

I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.

We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.

This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.

We once used a TI electronic fuse IC, but it liked to blow up.
Click to expand...

Crowbar circuit?

Sylvia.
 
On 01-Oct-22 7:49 pm, Phil Allison wrote:
Sylvia Else wrote:
-----------------------

Crowbar circuit?


** See JL\'s first post, forth para.



..... Phil
Click to expand...

Yes.

I like crowbars. No finesse required.

Sylvia.
 
On 30/09/2022 22:53, Phil Hobbs wrote:
Martin Rid wrote:
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
We make a gadget that\'s powered by a 12 volt wart, and sometimes
auser applies 24 and blows one up.We have a polyfuse and a 12 volt
TVS and they sometimes fry the TVS.It\'s posssible that most any
useful polyfuse+TVS combo can be teasedto destruction.I think Phil H
mentioned some gadget, a polyzorb or something, thatwould be better.
I can\'t find it.We might fine-tune the polyfuse+TVS, or maybe go
polyfuse and SCRcrowbar, or something.This is all entangled with
parts availabity. Ideally the box wouldjust work from 12 or 24, but
that has separate complications.We once used a TI electronic fuse IC,
but it liked to blow up.

Have some series resistance to work at 24v, and switch the
  resistance out if the voltage drops er stays under
  13v?

Cheers

Or maybe an LM393 and a PFET.

Cheers

Phil Hobbs
Click to expand...

A few years back the late Jim Thompson of this very bazaar posted a
circuit using two TL431 and two pmos fets to provide series undervolt,
overvolt and reverse polarity protection. All jelly bean very low cost
parts in unlimited supply?

piglet
 
On Saturday, October 1, 2022 at 4:39:28 AM UTC-4, Phil Hobbs wrote:
John Larkin wrote:
On Fri, 30 Sep 2022 17:53:05 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

Martin Rid wrote:
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in
message:r
We make a gadget that\'s powered by a 12 volt wart, and
sometimes auser applies 24 and blows one up.We have a polyfuse
and a 12 volt TVS and they sometimes fry the TVS.It\'s posssible
that most any useful polyfuse+TVS combo can be teasedto
destruction.I think Phil H mentioned some gadget, a polyzorb or
something, thatwould be better. I can\'t find it.We might
fine-tune the polyfuse+TVS, or maybe go polyfuse and
SCRcrowbar, or something.This is all entangled with parts
availabity. Ideally the box wouldjust work from 12 or 24, but
that has separate complications.We once used a TI electronic
fuse IC, but it liked to blow up.

Have some series resistance to work at 24v, and switch the
resistance out if the voltage drops er stays under 13v?

Cheers

Or maybe an LM393 and a PFET.


That\'s an idea, a pfet current limiter that entirely shuts off if
the input goes above maybe 14 volts. At maybe a 500 mA, fet
dissipation would be OK.

Someone here suggested making our own polyzen sort of thing, but I
suspect we couldn\'t successfully transfer the heat from the TVS to
the polyfuse fast enough.

An SMB12A TVS is rated for peak power, 600 watts, but not rated for
DC power. 5 watts maybe with big pads?

I\'ve occasionally looked at the specialized OVP/power limiter chips, but
they tend to cost $$$, and for my purposes they don\'t look as good as
doing the limiting locally. (If I were controlling big motors or
something, that might be a different matter.)

At various times I\'ve used LP2951s to make small amounts of +3.3V
directly from the wall wart to run startup circuitry and so forth. An
LM393 is a 358 with different metal--the input devices are lateral PNPs,
and so will take a lot of positive voltage regardless of the supplies.

A few microseconds of delay is no problem for that job.
Click to expand...

I haven\'t done a survey, and not going to, but looks like all the \"adaptor\" powered protection circuits use a debounce delay on the order of 15ms before they turn on the pass NFET. The debounce feature is an absolute necessity for idiot proofing against the people who push in a live plug. Turn-off is quite speedy at 100ns for the Kinetics Tech part I linked, and that is for the pass circuit to go high impedance- they don\'t crowbar anything. Crowbars are used to blow fuses, they\'re not used as a substitute for a clamp. Like I\'m telling you anything you don\'t already know.

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
Click to expand...
 
On Sat, 1 Oct 2022 04:39:15 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

John Larkin wrote:
On Fri, 30 Sep 2022 17:53:05 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

Martin Rid wrote:
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in
message:r
We make a gadget that\'s powered by a 12 volt wart, and
sometimes auser applies 24 and blows one up.We have a polyfuse
and a 12 volt TVS and they sometimes fry the TVS.It\'s posssible
that most any useful polyfuse+TVS combo can be teasedto
destruction.I think Phil H mentioned some gadget, a polyzorb or
something, thatwould be better. I can\'t find it.We might
fine-tune the polyfuse+TVS, or maybe go polyfuse and
SCRcrowbar, or something.This is all entangled with parts
availabity. Ideally the box wouldjust work from 12 or 24, but
that has separate complications.We once used a TI electronic
fuse IC, but it liked to blow up.

Have some series resistance to work at 24v, and switch the
resistance out if the voltage drops er stays under 13v?

Cheers

Or maybe an LM393 and a PFET.


That\'s an idea, a pfet current limiter that entirely shuts off if
the input goes above maybe 14 volts. At maybe a 500 mA, fet
dissipation would be OK.

Someone here suggested making our own polyzen sort of thing, but I
suspect we couldn\'t successfully transfer the heat from the TVS to
the polyfuse fast enough.

An SMB12A TVS is rated for peak power, 600 watts, but not rated for
DC power. 5 watts maybe with big pads?


I\'ve occasionally looked at the specialized OVP/power limiter chips, but
they tend to cost $$$, and for my purposes they don\'t look as good as
doing the limiting locally. (If I were controlling big motors or
something, that might be a different matter.)

At various times I\'ve used LP2951s to make small amounts of +3.3V
directly from the wall wart to run startup circuitry and so forth. An
LM393 is a 358 with different metal--the input devices are lateral PNPs,
and so will take a lot of positive voltage regardless of the supplies.

A few microseconds of delay is no problem for that job.

Cheers

Phil Hobbs
Click to expand...

We tried the TPS26600 \"hot swap efuse\" and it liked to blow up. It\'s a
horrible complex expensive power-pad thing.

I might just start with an LM2576 and switch down to maybe +7, and
work from there. That will work from 10 to 40 volts. 2576 is an old,
slow, klunky, non-synch switcher that\'s available. Wonderful part.

We could assume the dpak but we might lead-form the TO220 version in a
pinch. TO220s seem to be available. Maybe nobody wants them.

The guys wanted to use the LT8603 quad switcher but we tested it and
it makes nasty 400 MHz ringy things at the switching edges. In a
\"silent switcher\" !

We used the LTM8078 dual BGA module and had a similar problem; it
sprayed huge RF bursts all over the board. Probably the same
technology. The nasties are on both edges, so it\'s just switching too
fast, not an SRD effect.

https://www.dropbox.com/sh/ok9tn7gfgobv2nh/AADb7Muju5jRki93byL8J-_sa?dl=0

Had to redesign the big control board.
 
On Sat, 1 Oct 2022 11:46:56 +0100, piglet <erichpwagner@hotmail.com>
wrote:

On 30/09/2022 22:53, Phil Hobbs wrote:
Martin Rid wrote:
John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
We make a gadget that\'s powered by a 12 volt wart, and sometimes
auser applies 24 and blows one up.We have a polyfuse and a 12 volt
TVS and they sometimes fry the TVS.It\'s posssible that most any
useful polyfuse+TVS combo can be teasedto destruction.I think Phil H
mentioned some gadget, a polyzorb or something, thatwould be better.
I can\'t find it.We might fine-tune the polyfuse+TVS, or maybe go
polyfuse and SCRcrowbar, or something.This is all entangled with
parts availabity. Ideally the box wouldjust work from 12 or 24, but
that has separate complications.We once used a TI electronic fuse IC,
but it liked to blow up.

Have some series resistance to work at 24v, and switch the
  resistance out if the voltage drops er stays under
  13v?

Cheers

Or maybe an LM393 and a PFET.

Cheers

Phil Hobbs


A few years back the late Jim Thompson of this very bazaar posted a
circuit using two TL431 and two pmos fets to provide series undervolt,
overvolt and reverse polarity protection. All jelly bean very low cost
parts in unlimited supply?

piglet
Click to expand...

A polyfuse isn\'t a bad thing, to prevent blowing traces off a board
worst-case. I\'m emotionally opposed to using semiconductors to protect
semiconductors from power blunders.

Poly + diode handles the reversed supply situation OK. I\'ve just got
to handle the overvoltage case somehow.

We only use leaded polyfuses, the ones that look like disc caps. The
surface-mount ones are generally bad news.

Polyfuse + TVS can fail, but the TVS shorts, sort of like the skinny
guy jumping on top a hand grenade. Why didn\'t everybody just run?
 
On Sat, 1 Oct 2022 00:56:21 -0000 (UTC), Mike Monett VE3BTI
<spamme@not.com> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> wrote:

- OVP Protection
- no worst-case temp analysis done
Click to expand...

That works, but still needs reverse polarity protection.

Ideally the gadget will work at +12 or +24 or so, just not shut down.
That\'s a bit harder to do give today\'s parts situation.




Version 4
SHEET 1 1204 680
WIRE 160 -96 144 -96
WIRE 288 -96 160 -96
WIRE 512 -96 288 -96
WIRE 608 -96 512 -96
WIRE 672 -96 608 -96
WIRE 800 -96 768 -96
WIRE 832 -96 800 -96
WIRE 864 -96 832 -96
WIRE 144 -80 144 -96
WIRE 288 -80 288 -96
WIRE 512 -80 512 -96
WIRE 608 -80 608 -96
WIRE 832 -64 832 -96
WIRE 144 16 144 0
WIRE 608 16 608 0
WIRE 656 16 608 16
WIRE 688 16 688 -48
WIRE 688 16 656 16
WIRE 288 32 288 -16
WIRE 832 32 832 16
WIRE 688 48 688 16
WIRE 512 96 512 0
WIRE 560 96 512 96
WIRE 512 144 512 96
WIRE 688 144 688 128
WIRE 288 192 288 112
WIRE 304 192 288 192
WIRE 416 192 384 192
WIRE 448 192 416 192
WIRE 560 192 560 96
WIRE 608 192 560 192
WIRE 624 192 608 192
WIRE 288 224 288 192
WIRE 512 256 512 240
WIRE 688 256 688 240
WIRE 288 320 288 304
FLAG 144 16 0
FLAG 160 -96 Vin
FLAG 832 32 0
FLAG 288 320 0
FLAG 688 256 0
FLAG 656 16 M1G
FLAG 800 -96 Vout
FLAG 512 256 0
FLAG 608 192 Q1B
FLAG 416 192 Q2B
SYMBOL voltage 144 -96 R0
WINDOW 123 0 0 Left 2
WINDOW 3 -67 136 Left 2
SYMATTR SpiceLine Rser=2
SYMATTR InstName V1
SYMATTR Value PULSE(0 30 0 1 1 0 2)
SYMBOL pmos 768 -48 M270
WINDOW 0 70 46 VLeft 2
WINDOW 3 91 80 VLeft 2
SYMATTR InstName M1
SYMATTR Value FDC5614P
SYMBOL res 816 -80 R0
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL npn 624 144 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL res 672 32 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL res 592 -96 R0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL zener 304 -16 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value 1N759
SYMBOL res 272 16 R0
SYMATTR InstName R4
SYMATTR Value 1k
SYMBOL res 272 208 R0
SYMATTR InstName R5
SYMATTR Value 1k
SYMBOL res 400 176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL npn 448 144 R0
SYMATTR InstName Q2
SYMATTR Value 2N3904
SYMBOL res 496 -96 R0
SYMATTR InstName R7
SYMATTR Value 10k
TEXT 304 -216 Left 2 !.tran 2
TEXT 384 -248 Left 2 ;\'OVP protection
TEXT 512 -216 Left 2 !.options plotwinsize=0
TEXT 728 -216 Left 2 !.options nomarch


[Transient Analysis]
{
Npanes: 2
Active Pane: 1
{
traces: 1 {524291,0,\"V(vout)\"}
X: (\' \',1,0,0.2,2)
Y[0]: (\' \',0,-1,1,14)
Y[1]: (\' \',1,1e+308,0.6,-1e+308)
Volts: (\' \',0,0,1,-1,1,14)
Log: 0 0 0
GridStyle: 1
},
{
traces: 1 {524290,0,\"V(vin)\"}
X: (\' \',1,0,0.2,2)
Y[0]: (\' \',0,-3,3,30)
Y[1]: (\' \',1,1e+308,0.6,-1e+308)
Volts: (\' \',0,0,0,-3,3,30)
Log: 0 0 0
GridStyle: 1
}
}
Click to expand...
 
On Fri, 30 Sep 2022 19:08:54 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Friday, September 30, 2022 at 1:14:16 PM UTC-7, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.

So, is the power inlet clearly laser-burn-marked
as 12V center positive? And is the supplied power
brick similarly clearly labeled?
Click to expand...

Yes, but in a tangle of wart cords, people sometimes make mistakes. It
is prudent for instruments to be rugged. All our new stuff uses +24.

It\'s unfortunate that barrel connectors weren\'t keyed for voltages. Or
even marked.
 
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