tirsdag den 6. juni 2023 kl. 05.03.52 UTC+2 skrev John Larkin:
On Mon, 5 Jun 2023 17:08:21 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
mandag den 5. juni 2023 kl. 20.01.47 UTC+2 skrev John Larkin:
On Mon, 05 Jun 2023 18:54:16 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Mon, 05 Jun 2023 18:50:38 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Mon, 05 Jun 2023 09:21:32 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:
On Mon, 5 Jun 2023 12:10:05 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:
On 2023-06-04 23:05, John Larkin wrote:
On Mon, 05 Jun 2023 00:03:20 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Sun, 4 Jun 2023 15:45:44 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Sunday, June 4, 2023 at 6:13:39?PM UTC-4, John Larkin wrote:
On Sun, 04 Jun 2023 22:34:00 +0100, Cursitor Doom <c...@notformail.com
wrote:
Greetings, gentlemen,
As we all know, to get maximum efficiency out of a MOSFET, it needs to
be driven hard and fast and spend as little time between fully on and
fully off as possible. Does that same principle extend to Triacs? And
if so, how can that best be implemented when one has to use AC to
drive the gate?
CD.
Once a triac fires, the gate drive doesn\'t matter any more.
But they do need a hard, fast drive to fire properly, long enough to
let the drain current rise above the latch limit.
AC gate drive will be slow-rise, which could just possibly damage the
triac if the load current is high.
That should be on the data sheets.
I believe that is why a diac is typically used in the control circuit.
I thought diacs were sometimes used because triacs don\'t fire
symetrically, but I could be wrong.
So, as regards AC drive, is a higher frequency drive signal a safer
bet? Also, the load is AC too, so the thing will turn off at every
zero-crossing point, which makes life more complicated. :-(
With an AC load, an AC gate drive is probably OK. The triac will turn
on before the voltage gets too high, so the spreading damage mechanism
won\'t happen much.
The bad case is when there\'s a lot of voltage across the device with a
lot of instantaneous current behind it, and it gets a slow, wimpy
trigger.
Post your proposed circuit and we can discuss it.
I still call the terminals anode, gate, cathode. I can never remember
what\'s MT1 and MT2. Top and bottom would be OK too.
The triac is one of those parts where folks get confused by fossilized
analogies.
A triac is a bidirectional thyristor, but it does not behave like two
SCRs in antiparallel. SCR triggering only works in one quadrant, for a
start, so two antiparallel SCRs would be a two-quadrant device, whereas
triacs trigger in all four quadrants.
The triggering also isn\'t that symmetrical, because the structures
aren\'t--the second and fourth quadrant triggering mechanisms are fairly
different, and the four-layer stacks aren\'t well separated, as they
would be in two SCRs.
Triacs are also very slow even compared with SCRs, which are pretty poky
devices by modern standards.
Someplace I have a paper that goes into the details of real triac
operation--iirc it\'s a good read, but I\'m not laying my hands on it at
the moment.
(I haven\'t actually used a triac since I was a teenager, so this is just
out of general interest.)
Cheers
Phil Hobbs
I haven\'t designed in a triac for maybe 15 years now. I used a couple
of triacs to soft-start a giant power supply that had a 60 Hz power
transformer. Switch in a giant resistor on the primary side, wait a
second, then short it out. That was hard on resistors but prevented
the occasional 1000 amp startup surge. And allowed a little C&K power
switch on the front panel.
The customer insisted that we not use a switching power supply!
Real relays are usually cheaper than triacs, easier to drive, and
don\'t need heat sinks.
Yes, but you can\'t fire them on and off anything like as fast and they
don\'t have the same longevity AFAIK.
Plus a relay capable of switching 16A is going to be a hog, take up
loads of space compared to a triac and cost a hell of a lot more, I
would imagine.
It\'s easy to look up. Digikey has 15 amp relays starting around 60
cents.
The triac will need a heat sink, which will be big and cost more than
the triac.
yeh, this one looks nice at 8A, until you look at figure 2
https://files.seeedstudio.com/wiki/Grove-Solid_State_Relay/res/S208t02_datasheet.pdf
There\'s a shop in Fremont that will anodize infinite heat sinks.
it takes forever and the bill is infinite?
tirsdag den 6. juni 2023 kl. 05.03.52 UTC+2 skrev John Larkin:
On Mon, 5 Jun 2023 17:08:21 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
mandag den 5. juni 2023 kl. 20.01.47 UTC+2 skrev John Larkin:
On Mon, 05 Jun 2023 18:54:16 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Mon, 05 Jun 2023 18:50:38 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Mon, 05 Jun 2023 09:21:32 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:
On Mon, 5 Jun 2023 12:10:05 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:
On 2023-06-04 23:05, John Larkin wrote:
On Mon, 05 Jun 2023 00:03:20 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Sun, 4 Jun 2023 15:45:44 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Sunday, June 4, 2023 at 6:13:39?PM UTC-4, John Larkin wrote:
On Sun, 04 Jun 2023 22:34:00 +0100, Cursitor Doom <c...@notformail.com
wrote:
Greetings, gentlemen,
As we all know, to get maximum efficiency out of a MOSFET, it needs to
be driven hard and fast and spend as little time between fully on and
fully off as possible. Does that same principle extend to Triacs? And
if so, how can that best be implemented when one has to use AC to
drive the gate?
CD.
Once a triac fires, the gate drive doesn\'t matter any more.
But they do need a hard, fast drive to fire properly, long enough to
let the drain current rise above the latch limit.
AC gate drive will be slow-rise, which could just possibly damage the
triac if the load current is high.
That should be on the data sheets.
I believe that is why a diac is typically used in the control circuit.
I thought diacs were sometimes used because triacs don\'t fire
symetrically, but I could be wrong.
So, as regards AC drive, is a higher frequency drive signal a safer
bet? Also, the load is AC too, so the thing will turn off at every
zero-crossing point, which makes life more complicated. :-(
With an AC load, an AC gate drive is probably OK. The triac will turn
on before the voltage gets too high, so the spreading damage mechanism
won\'t happen much.
The bad case is when there\'s a lot of voltage across the device with a
lot of instantaneous current behind it, and it gets a slow, wimpy
trigger.
Post your proposed circuit and we can discuss it.
I still call the terminals anode, gate, cathode. I can never remember
what\'s MT1 and MT2. Top and bottom would be OK too.
The triac is one of those parts where folks get confused by fossilized
analogies.
A triac is a bidirectional thyristor, but it does not behave like two
SCRs in antiparallel. SCR triggering only works in one quadrant, for a
start, so two antiparallel SCRs would be a two-quadrant device, whereas
triacs trigger in all four quadrants.
The triggering also isn\'t that symmetrical, because the structures
aren\'t--the second and fourth quadrant triggering mechanisms are fairly
different, and the four-layer stacks aren\'t well separated, as they
would be in two SCRs.
Triacs are also very slow even compared with SCRs, which are pretty poky
devices by modern standards.
Someplace I have a paper that goes into the details of real triac
operation--iirc it\'s a good read, but I\'m not laying my hands on it at
the moment.
(I haven\'t actually used a triac since I was a teenager, so this is just
out of general interest.)
Cheers
Phil Hobbs
I haven\'t designed in a triac for maybe 15 years now. I used a couple
of triacs to soft-start a giant power supply that had a 60 Hz power
transformer. Switch in a giant resistor on the primary side, wait a
second, then short it out. That was hard on resistors but prevented
the occasional 1000 amp startup surge. And allowed a little C&K power
switch on the front panel.
The customer insisted that we not use a switching power supply!
Real relays are usually cheaper than triacs, easier to drive, and
don\'t need heat sinks.
Yes, but you can\'t fire them on and off anything like as fast and they
don\'t have the same longevity AFAIK.
Plus a relay capable of switching 16A is going to be a hog, take up
loads of space compared to a triac and cost a hell of a lot more, I
would imagine.
It\'s easy to look up. Digikey has 15 amp relays starting around 60
cents.
The triac will need a heat sink, which will be big and cost more than
the triac.
yeh, this one looks nice at 8A, until you look at figure 2
https://files.seeedstudio.com/wiki/Grove-Solid_State_Relay/res/S208t02_datasheet.pdf
There\'s a shop in Fremont that will anodize infinite heat sinks.
it takes forever and the bill is infinite?
On Tuesday, June 6, 2023 at 1:43:24â¯PM UTC-4, Lasse Langwadt Christensen wrote:
tirsdag den 6. juni 2023 kl. 05.03.52 UTC+2 skrev John Larkin:
On Mon, 5 Jun 2023 17:08:21 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
mandag den 5. juni 2023 kl. 20.01.47 UTC+2 skrev John Larkin:
On Mon, 05 Jun 2023 18:54:16 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Mon, 05 Jun 2023 18:50:38 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Mon, 05 Jun 2023 09:21:32 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:
On Mon, 5 Jun 2023 12:10:05 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:
On 2023-06-04 23:05, John Larkin wrote:
On Mon, 05 Jun 2023 00:03:20 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Sun, 4 Jun 2023 15:45:44 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Sunday, June 4, 2023 at 6:13:39?PM UTC-4, John Larkin wrote:
On Sun, 04 Jun 2023 22:34:00 +0100, Cursitor Doom <c...@notformail.com
wrote:
Greetings, gentlemen,
As we all know, to get maximum efficiency out of a MOSFET, it needs to
be driven hard and fast and spend as little time between fully on and
fully off as possible. Does that same principle extend to Triacs? And
if so, how can that best be implemented when one has to use AC to
drive the gate?
CD.
Once a triac fires, the gate drive doesn\'t matter any more.
But they do need a hard, fast drive to fire properly, long enough to
let the drain current rise above the latch limit.
AC gate drive will be slow-rise, which could just possibly damage the
triac if the load current is high.
That should be on the data sheets.
I believe that is why a diac is typically used in the control circuit.
I thought diacs were sometimes used because triacs don\'t fire
symetrically, but I could be wrong.
So, as regards AC drive, is a higher frequency drive signal a safer
bet? Also, the load is AC too, so the thing will turn off at every
zero-crossing point, which makes life more complicated. :-(
With an AC load, an AC gate drive is probably OK. The triac will turn
on before the voltage gets too high, so the spreading damage mechanism
won\'t happen much.
The bad case is when there\'s a lot of voltage across the device with a
lot of instantaneous current behind it, and it gets a slow, wimpy
trigger.
Post your proposed circuit and we can discuss it.
I still call the terminals anode, gate, cathode. I can never remember
what\'s MT1 and MT2. Top and bottom would be OK too.
The triac is one of those parts where folks get confused by fossilized
analogies.
A triac is a bidirectional thyristor, but it does not behave like two
SCRs in antiparallel. SCR triggering only works in one quadrant, for a
start, so two antiparallel SCRs would be a two-quadrant device, whereas
triacs trigger in all four quadrants.
The triggering also isn\'t that symmetrical, because the structures
aren\'t--the second and fourth quadrant triggering mechanisms are fairly
different, and the four-layer stacks aren\'t well separated, as they
would be in two SCRs.
Triacs are also very slow even compared with SCRs, which are pretty poky
devices by modern standards.
Someplace I have a paper that goes into the details of real triac
operation--iirc it\'s a good read, but I\'m not laying my hands on it at
the moment.
(I haven\'t actually used a triac since I was a teenager, so this is just
out of general interest.)
Cheers
Phil Hobbs
I haven\'t designed in a triac for maybe 15 years now. I used a couple
of triacs to soft-start a giant power supply that had a 60 Hz power
transformer. Switch in a giant resistor on the primary side, wait a
second, then short it out. That was hard on resistors but prevented
the occasional 1000 amp startup surge. And allowed a little C&K power
switch on the front panel.
The customer insisted that we not use a switching power supply!
Real relays are usually cheaper than triacs, easier to drive, and
don\'t need heat sinks.
Yes, but you can\'t fire them on and off anything like as fast and they
don\'t have the same longevity AFAIK.
Plus a relay capable of switching 16A is going to be a hog, take up
loads of space compared to a triac and cost a hell of a lot more, I
would imagine.
It\'s easy to look up. Digikey has 15 amp relays starting around 60
cents.
The triac will need a heat sink, which will be big and cost more than
the triac.
yeh, this one looks nice at 8A, until you look at figure 2
https://files.seeedstudio.com/wiki/Grove-Solid_State_Relay/res/S208t02_datasheet.pdf
There\'s a shop in Fremont that will anodize infinite heat sinks.
it takes forever and the bill is infinite?
Yeah, I\'d like to see how they calculate the fees on late payment. Let\'s see... 2% of infinity is infinity, so now you owe 2 * infinity which is infinity. Huh, the outstanding balance didn\'t change.
On 6/6/2023 2:56 PM, Ricky wrote:
On Tuesday, June 6, 2023 at 1:43:24â¯PM UTC-4, Lasse Langwadt Christensen wrote:
tirsdag den 6. juni 2023 kl. 05.03.52 UTC+2 skrev John Larkin:
On Mon, 5 Jun 2023 17:08:21 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
mandag den 5. juni 2023 kl. 20.01.47 UTC+2 skrev John Larkin:
On Mon, 05 Jun 2023 18:54:16 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Mon, 05 Jun 2023 18:50:38 +0100, Cursitor Doom <c...@notformail..com
wrote:
On Mon, 05 Jun 2023 09:21:32 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:
On Mon, 5 Jun 2023 12:10:05 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:
On 2023-06-04 23:05, John Larkin wrote:
On Mon, 05 Jun 2023 00:03:20 +0100, Cursitor Doom <c...@notformail.com
wrote:
On Sun, 4 Jun 2023 15:45:44 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Sunday, June 4, 2023 at 6:13:39?PM UTC-4, John Larkin wrote:
On Sun, 04 Jun 2023 22:34:00 +0100, Cursitor Doom <c...@notformail.com
wrote:
Greetings, gentlemen,
As we all know, to get maximum efficiency out of a MOSFET, it needs to
be driven hard and fast and spend as little time between fully on and
fully off as possible. Does that same principle extend to Triacs? And
if so, how can that best be implemented when one has to use AC to
drive the gate?
CD.
Once a triac fires, the gate drive doesn\'t matter any more.
But they do need a hard, fast drive to fire properly, long enough to
let the drain current rise above the latch limit.
AC gate drive will be slow-rise, which could just possibly damage the
triac if the load current is high.
That should be on the data sheets.
I believe that is why a diac is typically used in the control circuit.
I thought diacs were sometimes used because triacs don\'t fire
symetrically, but I could be wrong.
So, as regards AC drive, is a higher frequency drive signal a safer
bet? Also, the load is AC too, so the thing will turn off at every
zero-crossing point, which makes life more complicated. :-(
With an AC load, an AC gate drive is probably OK. The triac will turn
on before the voltage gets too high, so the spreading damage mechanism
won\'t happen much.
The bad case is when there\'s a lot of voltage across the device with a
lot of instantaneous current behind it, and it gets a slow, wimpy
trigger.
Post your proposed circuit and we can discuss it.
I still call the terminals anode, gate, cathode. I can never remember
what\'s MT1 and MT2. Top and bottom would be OK too.
The triac is one of those parts where folks get confused by fossilized
analogies.
A triac is a bidirectional thyristor, but it does not behave like two
SCRs in antiparallel. SCR triggering only works in one quadrant, for a
start, so two antiparallel SCRs would be a two-quadrant device, whereas
triacs trigger in all four quadrants.
The triggering also isn\'t that symmetrical, because the structures
aren\'t--the second and fourth quadrant triggering mechanisms are fairly
different, and the four-layer stacks aren\'t well separated, as they
would be in two SCRs.
Triacs are also very slow even compared with SCRs, which are pretty poky
devices by modern standards.
Someplace I have a paper that goes into the details of real triac
operation--iirc it\'s a good read, but I\'m not laying my hands on it at
the moment.
(I haven\'t actually used a triac since I was a teenager, so this is just
out of general interest.)
Cheers
Phil Hobbs
I haven\'t designed in a triac for maybe 15 years now. I used a couple
of triacs to soft-start a giant power supply that had a 60 Hz power
transformer. Switch in a giant resistor on the primary side, wait a
second, then short it out. That was hard on resistors but prevented
the occasional 1000 amp startup surge. And allowed a little C&K power
switch on the front panel.
The customer insisted that we not use a switching power supply!
Real relays are usually cheaper than triacs, easier to drive, and
don\'t need heat sinks.
Yes, but you can\'t fire them on and off anything like as fast and they
don\'t have the same longevity AFAIK.
Plus a relay capable of switching 16A is going to be a hog, take up
loads of space compared to a triac and cost a hell of a lot more, I
would imagine.
It\'s easy to look up. Digikey has 15 amp relays starting around 60
cents.
The triac will need a heat sink, which will be big and cost more than
the triac.
yeh, this one looks nice at 8A, until you look at figure 2
https://files.seeedstudio.com/wiki/Grove-Solid_State_Relay/res/S208t02_datasheet.pdf
There\'s a shop in Fremont that will anodize infinite heat sinks.
it takes forever and the bill is infinite?
Yeah, I\'d like to see how they calculate the fees on late payment. Let\'s see... 2% of infinity is infinity, so now you owe 2 * infinity which is infinity. Huh, the outstanding balance didn\'t change.
Do they charge by the square foot, you think? Hey, I wonder what the
factory floor space is like. I\'ll bet it\'s pretty big!