I asked if you mean by "none worked" that all AD797s you bought were fried ?
Kaput, Mertvo, Mort, Muerto, Morto ?
Kaput, Mertvo, Mort, Muerto, Morto ?
Död as in dead.... How dead? No current consumption, very dead? Have you tested an "alive" AD797 also? Is the connection a proven AD797 circuit?jacco vermeulen said:
They were used in a flea regulator (as gyrator) but output was 0V.
Using a normal opamp things worked.
Labeling of the chip was also different from the classic Analog Devices.
Now I'm waiting for some pcs from another supplier.
Cheers
Andrea
Using a normal opamp things worked.
Labeling of the chip was also different from the classic Analog Devices.
Now I'm waiting for some pcs from another supplier.
Cheers
Andrea
Can you show me the circuit in mind? It's possible that this opamp is unsuitable? Have you checked the suitability at all?
Actually the circuit (pinkfishmedia "flea") was designed around the AD797.
More info here: http://www.acoustica.org.uk/
Cheers
Andrea
BTW Johnny admitted a high failure rate of the batch and made a partial (30%) refund for a 100% failure rate....
More info here: http://www.acoustica.org.uk/
Cheers
Andrea
BTW Johnny admitted a high failure rate of the batch and made a partial (30%) refund for a 100% failure rate....
I wonder if the common mode input voltage might be something? the design has only a green LED 1.7-1.9 V and minimum is 3 volt and 2.5 V typical. It might be a design fault?
See http://focus.ti.com/lit/ds/symlink/opa627.pdf
Note between page 9 and page 13 are some really neat ideas about making this wonderful op-amp jump and sizzle ... Although it is not obvious from the text or drawings, really good performance can depend using a pair of close coupled plastic caps right next to the power supply pins ... this would be in addition to the rail filtering of the power source ... 😱
(Since the 8-pin DIP package is not yet available, us DIY types with tired old eyes may have to use the TO-99 cans in our circuits ... so don't ignore the PCB layout suggestions on page 9. Also those input diode camps on page 11 are always a good idea if you anticipate that this op-amp will be connected to the outside world = cheap insurance against killing the device from lightning, static or just plain ol' foolishness.)
Note between page 9 and page 13 are some really neat ideas about making this wonderful op-amp jump and sizzle ... Although it is not obvious from the text or drawings, really good performance can depend using a pair of close coupled plastic caps right next to the power supply pins ... this would be in addition to the rail filtering of the power source ... 😱
(Since the 8-pin DIP package is not yet available, us DIY types with tired old eyes may have to use the TO-99 cans in our circuits ... so don't ignore the PCB layout suggestions on page 9. Also those input diode camps on page 11 are always a good idea if you anticipate that this op-amp will be connected to the outside world = cheap insurance against killing the device from lightning, static or just plain ol' foolishness.)
Hi FE,
I put these in my CD Player and they sound very nice. Now, AndrewT is helping me with the Decoupling Cap values to make these sound even better (my CD Player was setup for 5534s).
Have you ever Biased these to Class A ala Carlosfm?
Thanks!
Regards//Keith
I put these in my CD Player and they sound very nice. Now, AndrewT is helping me with the Decoupling Cap values to make these sound even better (my CD Player was setup for 5534s).
Have you ever Biased these to Class A ala Carlosfm?
Thanks!
Regards//Keith
Hi Peranders,
Don't mind me asking an off topic question. From your web site, looks like you have tried AD745. How would you compare it to Opa627? With the adapter shown on your site, can I do a drop in replacement for Opa627?
Don't mind me asking an off topic question. From your web site, looks like you have tried AD745. How would you compare it to Opa627? With the adapter shown on your site, can I do a drop in replacement for Opa627?
peranders said:
Hi,
since many boards were built with this schematic I think the design is OK.
When a chip draws 500mA or more I tend to think it is not the chip it pretends to be.
Cheers
Andrea
John Lewman
This guy cant be trusted anymore.
He sold my friend (who organized a group buy of parts) a bunch of LM4562s and most of them around 90% of the bunch are not working. I bet another 10% would also be lower than standard.
Probably he sells graded or factory rejected items.
And then my friend tried to contact him to resolve the problem. He never replied again since then.
It is not so good is it? to make a profit like this. Selling things only without solving the sale's problem previously.
I've informed Nat Semi on this already and there will be A STRONG ACTION up on him for sure.
He had just made the DIY society a real bad reputation.
So, beware of this guy, my friends.
This guy cant be trusted anymore.
He sold my friend (who organized a group buy of parts) a bunch of LM4562s and most of them around 90% of the bunch are not working. I bet another 10% would also be lower than standard.
Probably he sells graded or factory rejected items.
And then my friend tried to contact him to resolve the problem. He never replied again since then.
It is not so good is it? to make a profit like this. Selling things only without solving the sale's problem previously.
I've informed Nat Semi on this already and there will be A STRONG ACTION up on him for sure.
He had just made the DIY society a real bad reputation.
So, beware of this guy, my friends.
Archwn said:
Likely.
What people don't realise is that such is the case with a great many "affordable" semi's.
And has been for ages, semi-conductor companies have a long history of dumping manufacture reject lots, and people have been warned for this on many occasions.
Hi jacco,
The shame here is that TI has forced many to look "Elsewhere" for the 627s in DIP. They won't be making any, from what they have said, until Spring 2008 sometime and all the reputable Vendors are high and dry! I don't know if this is the situation with the other chips discussed here too.
I wound up getting 12 OPA627BPs from a guy in Massachusetts on eBay with a very high satisfaction score. I just hope they are fine!
Believe me, I would have preferred to buy from DigiKey!
Regards//Keith
The shame here is that TI has forced many to look "Elsewhere" for the 627s in DIP. They won't be making any, from what they have said, until Spring 2008 sometime and all the reputable Vendors are high and dry! I don't know if this is the situation with the other chips discussed here too.
I wound up getting 12 OPA627BPs from a guy in Massachusetts on eBay with a very high satisfaction score. I just hope they are fine!
Believe me, I would have preferred to buy from DigiKey!
Regards//Keith
Yeah, i admit it's easy for me to say, i've used the 627/637 since day-1 of production and got me both APs and BPs by the dozens for $7/pc several years ago.
The line was meant as a general warning, the same thing happens with 5 cent transistors.
If someone takes the audio thing serious, and prefers not to be conned, he either buys in storage numbers or reaches for the next best Secure thing.
The line was meant as a general warning, the same thing happens with 5 cent transistors.
If someone takes the audio thing serious, and prefers not to be conned, he either buys in storage numbers or reaches for the next best Secure thing.
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