The simple 741 opamp circuit design ideas presented here are not only interesting but also very amusing to build.
The included circuit ideas using IC 741 like inverting and non-inverting amplifiers, tone control and regulated power supply will surely intrigue you. Circuit diagrams are also attached with the article.
Overview
We all are probably aware regarding the high versatility of the IC 741. Amazingly an infinite number of 741 opamp circuit design ideas can be wired by adding just a few passive components to it. We investigate a few of them here. IC 741 is one of the most versatile and multipurpose op-amp and can be wired up in numerous different ways. Let’s study some of the important 741 opamp circuit design configurations:
Inverting DC Amplifier:
Sometimes it becomes important for amplifying DC voltages, the diagram above shows how the IC can be wired up into an inverting DC amplifier circuit. As the name informs a DC input to the IC will be amplified at its output but will be just the opposite with polarity. VR1 may be used for adjusting the gain of the amplifier.
Non-inverting DC Amplifier:
This configuration is similar to the above circuit, the only difference being the output response, which is always equal to the polarity of the fed input voltage.
Inverting AC Amplifier:
The figure shows how the basic inverting DC mode of the IC can be simply modified into an inverting AC amplifier design. This circuit is intended to be used with AC or oscillating input signals, primarily for amplifying minute frequencies. C1 and C2 form the input and the output coupling capacitors. Again here the gain may be varied using the pot VR1.
Non-Inverting AC Amplifier:
The circuit is similar to the above explained design; the only difference being the output of the circuit provides oscillations in phase with the input whereas the previous design produces oscillations with opposite phase to that of the input.
Active Tone Control:
The opamp IC741 can be very effectively used for processing audio frequencies and customizing them as per one’s own choice.
Folks who prefer more bass in music may achieve it by just adjusting the bass control shaft whereas those who appreciate extra treble with music may do the same through another similar control reserved for the purpose.
The circuit diagram shows how by adding just a few passive components with the IC 741 a neat little active tone control circuit can be built.
For the given values, the circuit provides a bass boost of 12.5 dB and a cut of 10.5 dB at around 100 Hz.
The treble chill is of 8.8 dB with a cut of 9.8 dB at around 10 kHz, with respect to the set gain of the device at 1 kHz. The circuit also features high input impedance and low output impedance.
Regulated Power Supply Circuit Using opamp IC 741
The final diagram of this article shows a classic regulated voltage DC power supply using 741 opamp circuit design.
A cheap zener / resistor voltage reference is used to provide a reasonably stable reference to the non-inverting input of the IC.
The pot VR 1 is used to set the output voltage right from zero to a maximum of 15 volts continuously. A Darlington pair transistor is used at the output to enhance high current delivering capacity.
However another transistor T3 has also been incorporated to check the above current if it tends to drift beyond limit.
The control limit may be set by varying the value of the resistor R6.
In this post we discuss a couple of interesting application circuits using IC 741 which includes a simple power amplifier circuit and a regulated power supply circuit
This blog includes many interesting circuits which incorporates the IC 741 as the main active component for implementing the proposed functions. The present post explains yet a couple of more useful IC 741 application circuit ideas especially designed for the new electronic hobbyists.
Power Amplifier Circuit using IC 741
The first circuit diagram shows how the IC 741 can be configured as a high power amplifier circuit.
Though the maximum power of this amplifier is not more than 4 watts, the amplifier provides relatively good response with the applied frequency. The distortion of less than 0.5% and has a bandwidth of over 20kHz. The amplifier requires a minimum input of around 150 mV.
Regulated Power Supply Circuit using IC 741
The next circuit shows the IC 741 being wired up for providing a regulated power supply with an output which can be varied as per ones own requirement.Basically the IC is configured as a comparator cum driver for the proposed power delivering purpose. The employed zener diode has been included for fixing the non inverting of the IC with a constant refernce voltage.
An additional transistor BC107 has been included for making the circuit short circuit proof and also overload protected.
The output volts can be varied by adjusting the 10 K pot while the maximum current can be set by selecting or varying the 0.6 Ohm resistor appropriately as per the needs.
Well, these are the few popular IC 741 based opamp circuit ideas that I could collect and present, if you have more ideas regarding the topic please feel free to share them through the comments...
Geoff Nutley says
Hi Swagatam, could you suggest a circuit for testing a 741 to see if it is okay the reason being that I have a few of them in my collection and wanting to know if they are okay to use. I am also wanting to build a non contact AC voltage detector that uses a 5v piezo buzzer and a led for audio and visual detection.
Regards
Geoff
Swagatam says
Hi Geoff, you can connect the opamp as a comparator and check the output response.
connect any one of the input pins between the junction of two 10k resistors whose ends are connected to the supply rails.
connect the other input terminal to the center lead of a 10k preset or pot whose outer terminals are also connected with the supply rails….
connect a couple of LEDs, one from (+) to opamp output, and another from opamp output to (-), both having there own 1K resistors.
now flipping the pot to and fro should light-up/shut-off the Led alternately…proving the correct working of the opamp.
NITESH KUMAR says
Sir, please do a circuit on bass booster using opamp ic741
Swagatam says
Nitesh, the 5th circuit from top can be used for the mentioned purpose….in conjunction with a low pass filter
https://homemade-circuits.com/2016/01/design-low-pass-filter-circuit-quickly.html
Rakesh MAURYA says
Dear sir how to make voltage amplifier
when input voltage 1 V DC 200uA and Need a Output Voltage 2V DC 100mA
Swagatam says
that's impossible, unless an external power supply is used.
eshkariel tapiador says
Is the power supply's output regulated?…
How do I calculate the current limiter R6?…
It's variable voltage but not current?…
tnx for the patience 😀 Engr. Swagatam…
Swagatam says
thanks Eshkariel 🙂
yes the output will be regulated as long as the 24V or whatever input is fed is constant.
R6 = 0.6/current limit value
Soundhirarasan Shanmugam says
Hi sir, how to increase .5Vtoo 5v.? In my project i use piccontroller and sensor. My sensor gives oly .5v oly. So controller couldn 't take this voltage. How to boost up this voltage that can detect controller ..? Soundhirarasans@gmail.com… thanks in advance ….
Swagatam says
Hi Soundhirarasan, you can try a joule thief circuit as shown in this article:
https://homemade-circuits.com/2012/10/1-watt-led-driver-using-joule-thief.html
Ignatius junior says
sir, i want to build a parametric oscillator circuit. using a variable inductor. please can you provide me a circuit diagram
Swagatam says
Ignatius, using a variable inductor might not be possible for me, but here's one that uses a different principle you can check it out:
https://homemade-circuits.com/2014/06/making-ultrasonic-directive-speaker.html
Sanket Ajmire says
sir, I want to make an portable charger for a mobile by using a solar cell ,wind energy ,a battery and IC 741 so can you provide us circuit diagram and the list of component related to it as early as possible
Swagatam says
sanket, you can try the following circuit:
https://homemade-circuits.com/2015/09/solar-wind-2-input-hybrid-battery.html
Akshadeep says
Hi swagatm,
AS I mentioned that the Volts from the pulse coil at low rpms would be 200-250mv, may be 150 mv as well. So I have to eleminate R3 and the relay+diode and connect the collector pin of bc557(PNP) to the base of the PIC which will deliver 5 volts pulse to the PIC. Correct me If I am wrong.
Now the next querry is at highr rpms when the voltage from the pulse coil is 8-10 volts, Do I have to add a zener between the pulse coil and R1.
Waiting for your reply
Swagatam says
Hi Akashdeep, yes that's correct……. by "base of PIC" did you mean the input of PIC?
If the supply to the referred transistor circuit is fed with 5V then the input variations will not matter… . The collector of BC557 will always generate 5V regardless of the input variations.
for a safer response make R1 = 100K
Akshadeep says
Hi Swagatam,
From the pulse coil of my bike I get a pulse of 250 mv at low rpm which is not sufficient for the micro-controller to sense. But at higher rpms The pulse goes up to 8-1- volt.
I thought of adding an op-amp in between the Pulse coil and the micro-controller. So the pulse coil, a resistor, then 4007 diode, then a zener then op-amp and then to micro-controller. Will you plz specify how it should be with the schematics and the component values plz. The power source would be a 12 volt battery.
Swagatam says
Hi Akashdeep,
opamp may not be required for such a simple enhancement, you can use two BJTs and configure them as shown in the following example article:
https://homemade-circuits.com/2011/12/simple-and-useful-transistor-latch.html
Eliminate R3 and the relay+diode, those are not required, now you can use the collector of T2 for triggering the MCU.
joshua richard says
sir its me again
i have a low pass filter using [jrc4558] its is for home made [ home theater sub woofer] , its working but the problem is that i can here little transformer dramming coming from the sub woofer] its sounds mmgmmgmgmgmm….
my question is how can i reduce this problem because its really bad especially working with power amplifier and opm
Swagatam says
joshua, you can make and install a 50Hz notch filter circuit for sinking the interference or use an smps based circuit for powering the amp
prabhu Thiyagarajan says
Thank you very much sir . Once I done I let u know the result .
prabhu Thiyagarajan says
Sir, Tks for ur valuable comments . I understood. Ic 741 is for 1 o/p only . for my circuit I need to measure two resistors only . 1.2k & 4.5k only. Is there any dual op amp ic ? Pls help me n post the circuit sir .tks in advance.
Swagatam says
Prabhu, you can use LM358 IC for it.
you can try the first design shown in the following article:
https://homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
replace the zener diode with 1K or 10K and adjust the 10k preset either to shut off or light up as you want in response to the selected resistor.
prabhu Thiyagarajan says
Hi sir , by using op amp can I measure resistance . I need a o/p in a led indication. Fixed value ..let say if 1k red led need to light up if 10k green led need to light up …..pls help ..tks.
Swagatam says
Hi Prabhu, yes it can be done. But only for a single resistor for a particular setting, you cannot get multiple indications from one opamp at a time
joshua richard says
hi sir
can you send me a circuit of pre amplifier which gives output of bass only
Swagatam says
Hi Joshua,
you can try this circuit:
https://homemade-circuits.com/2013/06/make-this-low-pass-filter-circuit-for.html
Anonymous says
I have 9 mv AC signal need to be amplified upto 5V.which circuit can i use.
Neel
Swagatam says
You will need to make a small ferrite transformer for stepping it up. You can try the concept discussed in the following article:
https://homemade-circuits.com/2012/10/1-watt-led-driver-using-joule-thief.html
Anonymous says
hi.
Swagatam..can i have your mobile number for query ???
e-mail me kartikeyyadav@ymail.com
Swagatam says
I am sorry, i am comfortable interacting only through my blog.
shiva kulkarni says
Hi Sir,
i want to make a ic555 touch switch but cant't find enough info
can you give me detail info and circuit diagrams?
Swagatam says
Hi Shiva,
check out this one:
http://talkingelectronics.com/FreeProjects/555/555-TouchSw.gif
ashwin venkat says
Sir, Do you reside in bangalore? i just thought it would be good if we could meet once to talk on engineering and prototyping an electronic circuit.
Swagatam says
Thanks Ashwin! I stay in Mumbai, I wish we could meet.
Swagatam says
Thanks Ashwin! I stay in Mumbai, I wish we could meet.
Anonymous says
Good day sir, i want to make a water flow sensor circuit using ua741 op amps but i cant search a circuit diagram. . can youhelp me for this sir. thanks and God Bless!!!
Swagatam says
Good day, do you want a water flow sensor circuit or just a simple water sensor circuit??
Anonymous says
Sir, good day, ahm, water flow sensor circuit sir. . . can i ask for the diagram?
thanks.
Swagatam says
Good day, presently I do not have this circuit, will try to figure it out.
Swagatam says
It has to be from one power supply.
Anonymous says
It is also possible using two individual sources .
rhum Gamao says
sir,
i will forget that 50w portable audio amplifier, but can you help me to power up my lapel mic(rated 5 to 16w with 25w rms) since its power input ranges from 9v to 10v, if i can amplify a 3.7v battery form a cellphone it would be a big help on my part since i am using my lapel mic everyday in school. i have read a book talking electronics, there is a circuit there which was designed to boost 1.5v-4.5vdc upto 9v-10vdc, i already bought the components but the problem is there is no available rf choke inductor in my place and even the whole province. can you please help me… make my own voltage amplifier… really thank you for sharing your expertise to us… god bless you
Swagatam says
Hello Rhum,
A cell phone batt is rated at 3.7V 0.8AH, it is to be discharged at not more than 100mA rate, so it's power output capacity is 3.7 x 0.1 = 0.37 watts max, how can we make it work with 5 to 16 watts load??
By the way are you sure your mic consumes 5 to 16 watts?? just check it.
SamB says
Not sure what this mic is that takes so much power, but 25w rms is AC not DC. If it really does need 9v DC at 25W you will need a Motorbike or Alarm 12V sealed lead acid, and a simple voltage regulator to drop 12v to 9V. If your figures are correct you will need a Low dropout regulator with at least a 3A rating like the LM1085.
If your figures are wrong and you need a lover wattage portable 9-10v supply, try 8 standard 1.2v rechargeables (AA or AAA) in series.
If you still want to make the boost circuit, then inductors are quite easy to make for yourself.
rhum Gamao says
sir,
the power output of the voltage amplifier i'm trying to develop is 9v dc, since it is the required power input for my lapel mic(25w) and my 50w portable audio amplifier. it is very hard to find in our locality a 9v rechargeable battery and it is too expensive so im trying to develop a voltage amp so i may use my spare cellphone battery…tnx.. god bless!
Swagatam says
Hi Rhum,
50 watt is too high, a cell phone battery will not be able to support such high power load.
rhum Gamao says
sir,
can you help me, i am thinking of a 3.7v battery from a cellphone to be amplified or boost to have an output voltage of 9v dc in which i can use as power source for my lapel mic and my portable audio amplifier. can you recommend a circuit for it SIR.. Pls… thank you in advance…(ps. i've already tried op amp LM741 with 1k and 1.4K resistors for non-inverting but still the voltage was'nt amplified… i tried also using transistors like bc547 & bc338 with resistors, diode, capacitor and ferrite coil assembly and did'nt work… pls help me sir.)
Swagatam says
Please tell me what is the power output of your portable amp, if it's too high then it won't be feasible…
SamB says
For the 741 to output 9v it would have to have a power supply of at least 9v. To get a higher output than input you will have to convert to ac (oscillator) then use a transformer to change the voltage then rectify it. You will end up with a higher voltage but lower current.
Anonymous says
do I have to use the dual power supply or could I connect it to ground???
if I can't connect it to ground how could I use a standard twelve volt battery to acheive -12v?
Thanks
Swagatam says
A dual supply will be required for the above circuits, single supply will not work. You will have to use two 12v batteries.
Swagatam says
Hi Roger,
Yes you will require a dual power supply for all these circuits.