Re: Re: Re: Where complementary symmetry and traditional miller compensation rules supreme.
Hello Glen
As a general rule the thing you are buying should be potted, now I have seen unpotted transformers that are quite but I have never been able to buy them in small qty.
So I would be very careful of anything else, if you have to buy with the previso you can return them if they do not meet this condition.
Regards
Arthur
G.Kleinschmidt said:
Hi.
Buzzing like hell is a no-no
No, have not ordered from them before. Just phoned on Friday for price & lead-time. I have not emailed an official order yet. Was going to email the other night just after posting here, but then I noticed that once delivery and GST is added, their 800VA toroids cost the same as from Farnell. Still sorting out my Farnell BOM, so no orders placed yet.
Cheers,
Glen
Hello Glen
As a general rule the thing you are buying should be potted, now I have seen unpotted transformers that are quite but I have never been able to buy them in small qty.
So I would be very careful of anything else, if you have to buy with the previso you can return them if they do not meet this condition.
Regards
Arthur
Hmmm...... the biggest potted toroid I can get from any local distributer is 500VA. I've used plenty of toroids of various brands in the past without issue WRT to buzzing. Are the Harbuch Antrim units particularly bad for some reason? DC sensitive? (easilly solved).
Cheers,
Glen
Cheers,
Glen
Transformers
Hello Glen
It seems trivial to be able to get a high powered low noise transformer but this has not been my experience, on Harbuck I have not used their stuff, I am just saying to be carefull.
Ask Edmond about his experience with High powered transformer, his had I suspect lots of experience.
I cannot say if it is due to one thing like DC sensitivity, it can buzz because of how tightly and evenly it is wound. Also the take off point where the wire cames in and out of the transformer can have a strong field at this point so it needs to be rotated away for sensitive inputs.
It could just be that I have had lots of bad luck with large transformers. By the way how do you deal with DC sensitivity, curious.
Regards
Arthur
PS Sent you private email with my contact details we can speak over the phone much easier.
Hello Glen
It seems trivial to be able to get a high powered low noise transformer but this has not been my experience, on Harbuck I have not used their stuff, I am just saying to be carefull.
Ask Edmond about his experience with High powered transformer, his had I suspect lots of experience.
I cannot say if it is due to one thing like DC sensitivity, it can buzz because of how tightly and evenly it is wound. Also the take off point where the wire cames in and out of the transformer can have a strong field at this point so it needs to be rotated away for sensitive inputs.
It could just be that I have had lots of bad luck with large transformers. By the way how do you deal with DC sensitivity, curious.
Regards
Arthur
PS Sent you private email with my contact details we can speak over the phone much easier.
I've used a lot of Harbuch toroids.
Expensive, well made, heavy delivery charges, some noisy, delivery slow, probably no better than Farnell.
Hugh
Expensive, well made, heavy delivery charges, some noisy, delivery slow, probably no better than Farnell.
Hugh
FWIW, I've had good results with oversized toroids. I had a few 900VA transformers made on 1200VA cores. A tip I got from Burmeister Transformers in Germany. Absolutely silent, even under full load. I'm not sure about the mechanism (must have something to do with the low flux for the cross-section). You do pay for it though: you pay a 1200VA price for an 900VA xformer.
Jan Didden
Jan Didden
Re: Transformers
Not particular with toroids, rather double C-core transformers.
Cheers,
Edmond.
PHEONIX said:
Not particular with toroids, rather double C-core transformers.
Cheers,
Edmond.
Re: Re: Transformers
what is one double C-core
and what are those used for, what benefits?
any images, anyone?
Edmond Stuart said:
what is one double C-core
and what are those used for, what benefits?
any images, anyone?
thanks macura
ok, yes, I have seen double C-Core transformer before .. in some pictures from amplifiers
i do not remember which amplifiers
i will look into it and see.
If prices are right,
i may even try them for some amplifier
Double C Core, Secondaries:
S1= 280V-250V-0-250V-280V -- 125mA
S2= 0-5V-6,3V -- 2A
S3= 6,3-0-6,3 -- 3A
ok, yes, I have seen double C-Core transformer before .. in some pictures from amplifiers
i do not remember which amplifiers
i will look into it and see.
If prices are right,
i may even try them for some amplifier
Double C Core, Secondaries:
S1= 280V-250V-0-250V-280V -- 125mA
S2= 0-5V-6,3V -- 2A
S3= 6,3-0-6,3 -- 3A
Your previous signature ("you have the right to remain silent") was more in order. 😀
Why have you changed it so suddenly?
Why have you changed it so suddenly?
Toroidal transformers
Hello Edmond
Sorry for pulling you into this discussion on power transformers I just assumed you had experience with this type.
With C cores in the 1KVA range is it any issue to build a low noise (mechanical noise) transformer.
Regards
Arthur
Hello Edmond
Sorry for pulling you into this discussion on power transformers I just assumed you had experience with this type.
With C cores in the 1KVA range is it any issue to build a low noise (mechanical noise) transformer.
Regards
Arthur
LT1166
Back to an old topic: the auto-bias section of the LT1166.
Does anybody know why this circuit has been designed such that bias current of the OP devices depends on the temperature of this chip? According to the diagram (see below) it's about +0.2%/K.
Regrettably, the (description of the) simplified schematic doesn't give me any clue why and how this feature (or flaw?) has been added.
Next, as I have convergence problems with the spice model, could somebody else tell me if this model confirms the temperature dependency?
Cheers,
Edmond.
Back to an old topic: the auto-bias section of the LT1166.
Does anybody know why this circuit has been designed such that bias current of the OP devices depends on the temperature of this chip? According to the diagram (see below) it's about +0.2%/K.
Regrettably, the (description of the) simplified schematic doesn't give me any clue why and how this feature (or flaw?) has been added.
Next, as I have convergence problems with the spice model, could somebody else tell me if this model confirms the temperature dependency?
Cheers,
Edmond.
Attachments
Re: LT1166
Most likely, it's a complexity vs. performance trade, I though fail to see why this TC is a huge deal. This chip is not supposed to be thermally coupled with the output devices.
To solve your convergence issues, you may want to convert the attached LT1166 schematic that I reverse engineered some time ago to a SUBCKT. You may use two generic NPN and PNP models, but you need to have the device area as a parameter. I had absolutely no convergence issues with this model, however I don't think it will accurately model the TC you mentioned.
Edmond Stuart said:
Most likely, it's a complexity vs. performance trade, I though fail to see why this TC is a huge deal. This chip is not supposed to be thermally coupled with the output devices.
To solve your convergence issues, you may want to convert the attached LT1166 schematic that I reverse engineered some time ago to a SUBCKT. You may use two generic NPN and PNP models, but you need to have the device area as a parameter. I had absolutely no convergence issues with this model, however I don't think it will accurately model the TC you mentioned.
Attachments
Re: Re: LT1166
IOW, the TC is a flaw.
Of course this chip is not supposed to be thermally coupled with the OP devices, rather 'coupled' with the ambient temperature. As the latter may vary under worst conditions by say plus and minus 25 degrees C, that means a deviation of the idle current of plus and minus 5%. Admittedly not a huge deal, although performance wise, not really impressive as well.
Thanks, but the component values are hardly readable. If you can enlarge the font by simply change some setting, that would be very much appreciated.
Okay, but did you also simulate this model at different temperatures? If so, what effect had it on the OP bias current?
syn08 said:
IOW, the TC is a flaw.
Of course this chip is not supposed to be thermally coupled with the OP devices, rather 'coupled' with the ambient temperature. As the latter may vary under worst conditions by say plus and minus 25 degrees C, that means a deviation of the idle current of plus and minus 5%. Admittedly not a huge deal, although performance wise, not really impressive as well.
Thanks, but the component values are hardly readable. If you can enlarge the font by simply change some setting, that would be very much appreciated.
Okay, but did you also simulate this model at different temperatures? If so, what effect had it on the OP bias current?
Re: Re: Re: LT1166
http://www.synaesthesia.ca/files/LT1166.PNG
I did not simulate at different temperatures, but I have good reasons to believe it will not model correctly the datasheet TC.
Edmond Stuart said:
http://www.synaesthesia.ca/files/LT1166.PNG
I did not simulate at different temperatures, but I have good reasons to believe it will not model correctly the datasheet TC.
Syn08,
I have two queries, one OnT, one OffT:
OnT:
After Edmonds question I looked for a model for the 1166, but didn't find one. Your reverse engineered model looks quite detailed, how did you arrive at it?
OffT:
I am curious why you chose your particular domain name. Having read a lot about synaestesia lately, it jumped out to me. Care to enlighten me?
Jan Didden
I have two queries, one OnT, one OffT:
OnT:
After Edmonds question I looked for a model for the 1166, but didn't find one. Your reverse engineered model looks quite detailed, how did you arrive at it?
OffT:
I am curious why you chose your particular domain name. Having read a lot about synaestesia lately, it jumped out to me. Care to enlighten me?
Jan Didden