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Is LM324 exactly equal to four LM741s ?!

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aomidee

aomidee

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hi everybody
can i use one LM324 instead of each four 741s in my circuit? is it necessary to make any changes? can i apply -15volts to Ground pin of LM324? in this way,are all four op-amps in LM324 supplied with +15 & -15 Vccs?
 

Hi,
Yes,
but be careful with supply & input voltages!
An LM324 can have abs. MAX ONLY +/-16V and an
LM741 up to +/-22V!
Other data are similar...
K.
 

    aomidee

    aomidee

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Other data are similar
Click to expand...
Both are bipolar OPs with about 1MHz unity gain bandwidth and 0.5 V/us slew rate. Other properties are
considerably different. LM324 e.g. has a class B output stage causing unpleasant crossover distortions. But
it's suitable for single supply applications and has a low quiescent current.
 

The LM324 quad opamp and the LM358 dual opamp are low power which in those days meant low performance:
1) Its output transistors have no bias current so they have up to 3% crossover distortion.
2) Its transistors use low current so they are slow. At an output of only 14V p-p it turns frequencies above 5kHz into triangle waves with reduced level.
3) Its inputs work at the negative supply voltage that can be ground.
4) Its output goes nearly to the negative supply voltage that can be ground.
5) Its minimum supply is only 3V.

An LM348 is a quad 741 and is also nearly 42 years old like the 741. They both have the same poor performance.
 

It's worth adding that the term 'op-amp' was originally given to a device intended to convert DTL, ECL and TTL digital levels to higher voltages and vice versa. They were intended to interface to devices such as teleprinter magnets, core stores and small motors. The fact that they are 'reasonable' as linear amplifiers is almost coincidental.

Of course, there is now a vast range of amplifiers which can out-perform them at linear applications.

Brian.
 

It's worth adding that the term 'op-amp' was originally given to a device intended to convert DTL, ECL and TTL digital levels to higher voltages
Click to expand...
Never heard about! As far as I know, the first OPs have been vacuum tube circuits in world war II military analog computers, see e.g. https://en.wikipedia.org/wiki/Operational_amplifier
 

You have to watch your input circuits (maybe outputs too);
324's have pnp inputs, (that's why they go to - supply)
741's have npn inputs,
so see that input bias currents are available in the required direction
- current out from 324 inputs.
 

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