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the right op amp?...

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bouvett

New Member
hi,
i need to buy some general purpose op amps which are monorail(i mean i can connect the op amp with Vcc and Gnd not Vcc Gnd and -Vcc) any ideas of such opamps.. possibly sold from ebay?

thanks guys

regards
 

ericgibbs

Well-Known Member
Most Helpful Member
hi,
i need to buy some general purpose op amps which are monorail(i mean i can connect the op amp with Vcc and Gnd not Vcc Gnd and -Vcc) any ideas of such opamps.. possibly sold from ebay?

thanks guys

regards
hi,
I like the CA3140 and CA3240 OPA,s good single voltage spec and cheap.:)
 

Arkham00

Member
Preferred op-amps

My preferred general purpose op-amps (low-cost, pdip package, rail-to-rail if possible, single supply), to complement microcontroller projects, are the following

  • MC34074 (OnSemi) - V=3/44, GBW=4.5MHz, Bipolar (no R-R), 0.71€
  • MC33174 (OnSemi) - V=3/44, GBW=1.8MHz, Bipolar (no R-R), 0.70€
  • MC33204 (OnSemi) - V=2/12, GBW=2.2MHz, Bipolar, 0.96€
  • TLV2374 (TI) - V=3/16, GBW=3MHz, CMOS, 0.81€
  • TLC274 (TI) - V=3/16, GBW=1.7MHz, CMOS, 0.46€
  • TLV2464 (TI) - V=2.7/6, GBW=6.4MHz, CMOS, 1.48€
  • LM6134 (NSC) - V=2.7/12, GBW=10MHz, Bipolar, 2.82€
  • LMC6484 (NSC) - V=3/15, GBW=1.5MHz, CMOS, 2.55€
  • MCP604 (Microchip) - V=2.7/6, GBW=2.8MHz, CMOS, 0.78€
 

bouvett

New Member
hi,
I like the CA3140 and CA3240 OPA,s good single voltage spec and cheap.:)
thanks for your reply...
these seem to be much of an overkill considered that i need the op amps for general purposes only... i mean normal (or standard uses) (not for some cutting edge technology :p)
:)
 

bouvett

New Member
My preferred general purpose op-amps (low-cost, pdip package, rail-to-rail if possible, single supply), to complement microcontroller projects, are the following

  • MC34074 (OnSemi) - V=3/44, GBW=4.5MHz, Bipolar (no R-R), 0.71€
  • MC33174 (OnSemi) - V=3/44, GBW=1.8MHz, Bipolar (no R-R), 0.70€
  • MC33204 (OnSemi) - V=2/12, GBW=2.2MHz, Bipolar, 0.96€
  • TLV2374 (TI) - V=3/16, GBW=3MHz, CMOS, 0.81€
  • TLC274 (TI) - V=3/16, GBW=1.7MHz, CMOS, 0.46€
  • TLV2464 (TI) - V=2.7/6, GBW=6.4MHz, CMOS, 1.48€
  • LM6134 (NSC) - V=2.7/12, GBW=10MHz, Bipolar, 2.82€
  • LMC6484 (NSC) - V=3/15, GBW=1.5MHz, CMOS, 2.55€
  • MCP604 (Microchip) - V=2.7/6, GBW=2.8MHz, CMOS, 0.78€
yes good choice but unfortunatly they are not very available on ebay.. (my source for buying electronic components..) ow i only had experience with the lm 741 but this turned out to be dual supply
till n
 

ericgibbs

Well-Known Member
Most Helpful Member
thanks for your reply...
these seem to be much of an overkill considered that i need the op amps for general purposes only... i mean normal (or standard uses) (not for some cutting edge technology :p)
:)
I would hardly think a 28pence OPA, first manufactured over 15 years ago could be considered cutting edge technology.:confused:

For general purpose use the CA3140/3240 is ideal, IMO.

If you are thinking in terms of the 741 type, dont waste your time.:)
 
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bouvett

New Member
I would hardly think a 28pence OPA, first manufactured over 15 years ago could be considered cutting edge technology.:confused:

For general purpose use the CA3140/3240 is ideal, IMO.

If you are thinking in terms of the 741 type, dont waste your time.:)

with regards to the general purpose opamp and the cutting edge technology.. the former term was used to stress the point that i need a really basic opamp... just to make things clearer not to provide any comment on any opamps listed above..

why is the LM741 a waste of time ?? (just curiosity)

what i want is an opamp having a single supply and can work with voltages as low as 5V possibly less... thanks regards
 

Nigel Goodwin

Super Moderator
Most Helpful Member
with regards to the general purpose opamp and the cutting edge technology.. the former term was used to stress the point that i need a really basic opamp... just to make things clearer not to provide any comment on any opamps listed above..

why is the LM741 a waste of time ?? (just curiosity)
Because it's a low spec antique, you can buy FAR better devices for less money - the Texas TL0xx series are very popular and pretty good spec.

what i want is an opamp having a single supply and can work with voltages as low as 5V possibly less... thanks regards
Why do you specifically require single supply?, any opamp can work off a single supply, you just bias it at half supply potential, which is all the 'single supply' chips do. 5V or less is really what's limiting you though.

For my analogue PIC tutorial I required an opamp that went down to zero volts and to +2.5V or so. To do this I used a normal cheap opamp along with a negative voltage generator to supply a -5v for it. This allows it to go right down to zero volts, which so called 'rail to rail' devices don't.
 

bouvett

New Member
Why do you specifically require single supply?, any opamp can work off a single supply, you just bias it at half supply potential, which is all the 'single supply' chips do. 5V or less is really what's limiting you though.

For my analogue PIC tutorial I required an opamp that went down to zero volts and to +2.5V or so. To do this I used a normal cheap opamp along with a negative voltage generator to supply a -5v for it. This allows it to go right down to zero volts, which so called 'rail to rail' devices don't.
what do you mean with "any opamp can work off a single supply, you just bias it at half supply potential,"?
so if i have a dual supply opamp, and i need to work with only Gnd and 5V, i just connect the V+ to 5v and V- to gnd even though it is dual supply??
 

Arkham00

Member
The right op-amp

Ok, now I understand what you want.
You need an LM324 (it's a quad op-amp in a 14 pin package).
Very cheap, very easy to find on ebay, single, wide range supply, low current, ...
Quite old and with much better alternatives now but still useful for a lot of circuits.
 

audioguru

Well-Known Member
Most Helpful Member
A lousy old LM358 dual opamp is half of a lousy old LM324 quad opamp. It is in an 8-pins package.

They are noisy and have a full output bandwidth to only about 2kHz.
 

Vizier87

Active Member
Yeah... I was gonna ask that too, but I was impeded by the 'sticky' posts... :eek:

I've used LM358 (dual opamp) for comparators and they work well. The problem is for amplification from very small outputs (like the LM35), like the ones in the 'sticky' op-amp covers the ac-coupling, not the low-frequency (or zero) ones.
Or am I mistaken? Do we use the instrumentational amplifier for the output of LM35?
and........How do we produce -5V to be fed into the negative rail?
 

audioguru

Well-Known Member
Most Helpful Member
The MC33171 single, MC33172 dual and MC33174 quad opamps are low power improvements to the lousy old LM358 dual and LM324 quad opamps.

They have exactly the same low supply current, inputs and output that work at 0V and minimum supply of 3V.
But they do not have the horrible crossover distortion and have a full output bandwidth to 35kHz. Their max supply is 44V.

I use them in battery powered circuits.
 

bouvett

New Member
Try reading the 'sticky' at the top of this very forum.

hi nigel, i saw the sticky note diagram...thanks a lot, one last question just to make sure... the single supply technique shown in the diagram is for when one needs to use only a single supply and the op amp is made to work with dual supply right?

thanks
 

Nigel Goodwin

Super Moderator
Most Helpful Member
by the way i am not really sure at the moment but the non inverting single supply circuit posted in the sticky note and in:
No, it's the same - you generate a half supply rail.

Even so-called 'single supply' devices do just the same - you bias it at half supply potential. There's no 'magic' single supply opamp.

An opamp is an opamp, it doesn't make any difference if you use it as a comparator, it's still an opamp.
 
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