How does this work ? - Page 2 - Electronic Circuits Projects Diagrams Free

ikalogic · 6th January 2007, 05:15 AM

Quote:

Originally Posted by ahmedragia21

ya philpa , i agree with ya im going to buy a pair of fairchild reflective sensor IR tx,rx ..

another question , for unpredictable ligh condition , the pot works or there's another better method ?

yes, the pot works, but you need a pot of high value, say 100K, so that it gives you a wide working spectrum. and also it will be compatible with many types of LDRs.

Ahmed, why you hate op-amps?

audioguru · 6th January 2007, 05:24 AM

Quote:

Originally Posted by ikalogic

you can use an LM358.

This is 2007. An LM358 is too old today:
1) It is noisy. Low noise opamps have been available for many years.
2) It has crossover distortion because it was the 1st "low power" opamp so they left out bias current for its output transistors. Even guitar fuzz people don't like its fuzzy sound.
3) It has a full output bandwidth to only 6kHz like an old AM radio (remember them?). Modern opamps go to 100kHz.

Opamps don't need a negative supply if their inputs are biased correctly.

ikalogic · 6th January 2007, 05:51 AM

Quote:

Originally Posted by audioguru

This is 2007. An LM358 is too old today:
1) It is noisy. Low noise opamps have been available for many years.
2) It has crossover distortion because it was the 1st "low power" opamp so they left out bias current for its output transistors. Even guitar fuzz people don't like its fuzzy sound.
3) It has a full output bandwidth to only 6kHz like an old AM radio (remember them?). Modern opamps go to 100kHz.

Opamps don't need a negative supply if their inputs are biased correctly.

again, am learning every day! a last favor: any part names? which Dual Op-amp yould use now? an op-amp with the features you'r talking about..?

audioguru · 6th January 2007, 06:48 AM

I use the inexpensive, low noise, low distortion and wide bandwidth TL071 single, TL072 dual and TL074 quad opamps invented by Texas Instruments but are made by them and also by many other semiconductor manufacturers. They have FET inputs so don't have bias current. They have been used in many home entertainment products for about 25 years.

There are much better opamps available at higher cost but they sound the same as these. These have 0.003% distortion. The better ones have only 0.00008% distortion. The better ones are OPA134, OPA2134 and OPA4134 also made by Texas Instruments.

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6th January 2007, 06:48 AM	(permalink)
audioguru	I use the inexpensive, low noise, low distortion and wide bandwidth TL071 single, TL072 dual and TL074 quad opamps invented by Texas Instruments but are made by them and also by many other semiconductor manufacturers. They have FET inputs so don't have bias current. They have been used in many home entertainment products for about 25 years. There are much better opamps available at higher cost but they sound the same as these. These have 0.003% distortion. The better ones have only 0.00008% distortion. The better ones are OPA134, OPA2134 and OPA4134 also made by Texas Instruments. __________________ Uncle $crooge