There are many 741 compatible chips readily obtainable; however, the problem is that many students and colleges are not aware of the different manufacturers and the model numbers. Consequently, many chips have been getting expensive due to students relying too much on one model and manufacturer.
The 741 is the one everyone thinks of when looking for a general-purpose amplifier, however, if you rely too much on the same chip and seller, they will sometimes artificially hike up their prices. You can make your budget stretch further if you look for cheaper equivalents.
Almost all the modern 8-pin operational amplifiers take their architecture from the earlier 741 chip. Many manufacturers have made minor changes to the original design, however for the most part they are pinout equivalents, and the same formula for gain calculation applies.
If you were using an op amp for simple educational experiments to calculate the gain, or perhaps for simple basic op amp circuits, then many cheaper equivalents would perform just as effectively, and save you money. I have compiled a list of my favourite chips that are readily available and affordable.
The LM741 is a classic op amp chip and as you can see, it has a very simple and standard layout that is identical to all the chips mentioned on this page. This is a general-purpose amplifier utilising bi-polar transistor technology.
These come in two flavours, the 741 and 741 A can operate on split voltage rails of +22 V and -22 V, whilst the LM741C requires +18 V and -18 V.
Even with all the modern day equivalents, the LM741CN is still a very cost effective chip at around 54p each or 32p when you buy 100 from Farnell.
CA3140E is pin equivalent to the LM741. There is a minor difference in that pin 8 is for the strobe function, which controls the output, however, for basic op amp circuits it is not used.
The CA3140E is a direct replacement for the 741, and the manufacturers designed it with this being the main purpose.
The input and output stages of this chip use MOSFET transistors, hence, Bi-MOS technology is utilised in its design.
TL081CN is another favourite of mine because it is affordable. You can pick one of these up from Maplin for around 62p whilst you are on your way to the chip shop.
This is a general-purpose operational amplifier with a JFET input, which is even better because its input impedance will be high. This means you could connect the inputs directly to a signal source with minimal impedance issues.
Your basic op amp circuit configurations will be the same and you will be using the same formulas.
TL061CP is a great op amp chip manufactured by Texas Instruments. Just like the TL081CN, it has a JFET input stage. It is a general-purpose operational amplifier, which replaces the 741. You can get these from RS at very affordable prices.
TL071CP is also another great general-purpose operational amplifier by Texas Instruments. It has JFET inputs and is pin compatible with the 741.
ST Microelectronics manufactures LF351N. It has JFET inputs just as the previous one. This one has a wide bandwidth, which is even better. The maximum supply voltage is +18 V and -18 V.
This is a lovely operational amplifier chip that I have used many times and is very affordable. You could get 10 chips for around £2.50 on eBay and it comes directly from China.
MC33171N by ST Microelectronics is a bi-polar general-purpose operational amplifier. This is one of my favourites as it is almost identical to the old 741 in technology. This one is the most affordable I could find from Farnell at just 38p each or 29p when you buy 100.