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** Nope.No other difference? alternistor = triac ?
its just that a number of apparently unrelated companies use the term
alternistor for what otherwise seems to be traic
They seem to be a special case version though:No other difference? alternistor = triac ?
its just that a number of apparently unrelated companies use the term
alternistor for what otherwise seems to be traic
I'd managed to miss that distinction along the way. It seems odd that RS,On 23/05/2013 10:46, N_Cook wrote:
No other difference? alternistor = triac ?
its just that a number of apparently unrelated companies use the term
alternistor for what otherwise seems to be traic
They seem to be a special case version though:
http://www.littelfuse.com/data/en/Data_Sheets/E4AlternistorTriac.pdf
Also, Wiki says: "A TRIAC which can only operate in quadrants I through
III, and cannot be triggered in quadrant IV, has improved turn-off
(commutation) characteristics.
These devices are made specifically for improved commutation when
controlling a highly-inductive load, such as a motor or solenoid, an
application where normal TRIACs have problems due to high
voltage/current angles"
--"N_Cook"
No other difference? alternistor = triac ?
** Nope.
its just that a number of apparently unrelated companies use the term
alternistor for what otherwise seems to be traic
** The term refers to a special type of triac that has a very high
dv/dt rating - so high, that in most applications there is no need
for a RC snubber.
With ordinary triacs, a fast rising voltage wave or a high frequency
wave will cause the device to trigger itself on.
Not so with an alternistor.
.... Phil
googlingLee <cyberwitch@ukonline.net> wrote in message
news:b06j83F13nmU1@mid.individual.net...
On 23/05/2013 10:46, N_Cook wrote:
No other difference? alternistor = triac ?
its just that a number of apparently unrelated companies use the term
alternistor for what otherwise seems to be traic
They seem to be a special case version though:
http://www.littelfuse.com/data/en/Data_Sheets/E4AlternistorTriac.pdf
Also, Wiki says: "A TRIAC which can only operate in quadrants I through
III, and cannot be triggered in quadrant IV, has improved turn-off
(commutation) characteristics.
These devices are made specifically for improved commutation when
controlling a highly-inductive load, such as a motor or solenoid, an
application where normal TRIACs have problems due to high
voltage/current angles"
I'd managed to miss that distinction along the way. It seems odd that RS,
probably the largest industrial electronic components supplier in the UK ,
makes no mention of them alongside or within their triac listings.
** But "snubberless triac " works a treat.googling
alternistor "600 volt" site:co.uk
throws up no UK suppliers for 600V alternistors
googling
alternistor "600 volt" site:co.uk
throws up no UK suppliers for 600V alternistors
luckily no one ever uses a snubber in this use, usually just a triac, so
replaced with an ordinary 600V triac and turns on and off ok, presumably
maker had a stock of alternistors , so used them instead of a triac there
Digikey seemed to list alternistors but not 600V ones.googling
alternistor "600 volt" site:co.uk
throws up no UK suppliers for 600V alternistors
luckily no one ever uses a snubber in this use, usually just a triac, so
replaced with an ordinary 600V triac and turns on and off ok, presumably
maker had a stock of alternistors , so used them instead of a triac
there
Depends whether you count Digikey as a UK supplier (they have UK pricing
and supply to the UK) - they list them anyway.
--Lee <cyberwitch@ukonline.net> wrote in message
news:b08vu5Fh3enU1@mid.individual.net...
googling
alternistor "600 volt" site:co.uk
throws up no UK suppliers for 600V alternistors
luckily no one ever uses a snubber in this use, usually just a
triac, so replaced with an ordinary 600V triac and turns on and off
ok, presumably maker had a stock of alternistors , so used them
instead of a triac there
Depends whether you count Digikey as a UK supplier (they have UK
pricing and supply to the UK) - they list them anyway.
Digikey seemed to list alternistors but not 600V ones.
The failed one has no T1-gate resistance in the 10s to low hundreds
of ohms, is that a (sometimes) characteristic of alternistors ?
otherwise no gas venting through the epoxy fill or other signs of
distress
The alternistor is one I'd forgotten until it was just mentioned.Phil Allison wrote:
"N_Cook"
No other difference? alternistor = triac ?
** Nope.
its just that a number of apparently unrelated companies use the term
alternistor for what otherwise seems to be traic
** The term refers to a special type of triac that has a very high
dv/dt rating - so high, that in most applications there is no need
for a RC snubber.
With ordinary triacs, a fast rising voltage wave or a high frequency
wave will cause the device to trigger itself on.
Not so with an alternistor.
.... Phil
--
Phil is correct. Also called Snubberless Triacs by some manugacturers.
Another thing I can add is that the construction of an alternistor is that
of two inverse-parallel connected SCRs. This arrangement has been long
known to avoid the triggering problems associated with using a triac to
control highly inductive loads, such as motors.
Its a long shot - but check out the ST semiconductor range of triacs forLee <cyberwitch@ukonline.net> wrote in message
news:b08vu5Fh3enU1@mid.individual.net...
googling
alternistor "600 volt" site:co.uk
throws up no UK suppliers for 600V alternistors
luckily no one ever uses a snubber in this use, usually just a triac,
so
replaced with an ordinary 600V triac and turns on and off ok,
presumably
maker had a stock of alternistors , so used them instead of a triac
there
Depends whether you count Digikey as a UK supplier (they have UK pricing
and supply to the UK) - they list them anyway.
Digikey seemed to list alternistors but not 600V ones.
The failed one has no T1-gate resistance in the 10s to low hundreds of
ohms,
is that a (sometimes) characteristic of alternistors ? otherwise no gas
venting through the epoxy fill or other signs of distress
Also, Wiki says: "A TRIAC which can only operate in quadrants I through
III, and cannot be triggered in quadrant IV, has improved turn-off
(commutation) characteristics.
These devices are made specifically for improved commutation when
controlling a highly-inductive load, such as a motor or solenoid, an
application where normal TRIACs have problems due to high voltage/current
angles"