How to Build a Simple Function Generator Circuit

In this video, we demonstrate a simple function generator built with a single chip, an LM324. This function generator outputs square, triangle, or sine waves. It also allows for frequency to be adjusted, as well as amplitude.

[ruhnet]

I believe the reason you were seeing the sine wave move around on the scope is because the DC offset of the final output signal was changing when you adjusted the pot. If you use a capacitor in series with the output it should eliminate that DC offset and just allow through the sine wave. Thanks for the video and good luck with your projects :-D

[DownhillAllTheWay]

I built this and got identical waveforms. At first, I used a dual supply with two 9V batteries.
[Pos to to circuit]
The line above shows the two 9V batteries connected back to back, with Gnd in between.

The waveforms were just like the ones shown - a little wiggle half way up the rising and falling edges of the square wave, a little spike at the top of the triangle, and a sine wave at a much lower amplitude, that moved up and down as the pot was twiddled.

But I didn't like the two-battery arrangement, so rewired it with a single battery, and the fourth op amp configured as a voltage follower, following the voltage from a voltage divider from +4.5V to -4.5V to produce a pseudo-ground.

[+ 9v -] << battery
+4.5V | | -4.5V R1 = R2
|--R1---R2--| or you can use a 10K pot
Pos | Neg |\

10 | \ 8
| pseudo-Gnd
| / |
- / |
| 9 |/ |
| |


Of course the waves were smaller, as they were running from +/- 4.5V instead of +/- 9V, but apart from that everything worked the same.

[GeorgeGeorge-xjbc]

Using LM324 the square wave pulse in the scope has a very high slew rate, it is the time that needs for transistion from high to low and vice versa so the form is not square but trapezoid.Replace LM324 with TL084 and the output will become real square.Another major factor is the duty cycle has to be exactly in 50%.

[espenbgh]

Frequency range? what about the spikes on the triangel wave?

[thepussygrabbingfamilyvalu]

it would be nice if if you could explain how the circuit works and how this specific combination of cap/resistance generate various wave functions....

[tonyd]

Good work on that signal generator. Thank you for making & posting this video.

[joerinaldi]

How do you see the thee waveforms. Does your Oscilloscope have three channels. Mine only has two.

[dougeverett]

what makes a trace move up and down on a scope? A DC potential. Set the input to AC for pink channel.

[Electalexis]

When you integrate a triangular wave you dont come with a sin wave.... It's a polynôme wave

[meriemkechroud]

Hi please we can simulate this on proteus using the same shema

[givenfirstnamefamilyfirstn]

The link’s breadboard diagram shows pin 10, the non inverting sine stage input connected to the negative supply voltage and not the same earth rail as the equivalent pin on the two earlier stages. Is this the way the actual circuit was connected?
The sine wave output was a bit funny and had a phase shift.

[Kennynva]

How do you hook up batteries as a power supply???

[seyedmarashi]

thank for ice video, just let me know the frequency start range and end range. i think it should be 10HZ to 12KHZ

[Retfosho]

What is the max frequency of this circuit?

[td]

I went to the website, to study the project. The components list names a 1nF cap, as the last part. I do not see it used on the schematic, or the breadboard. Is it needed? Where would it be placed? Thank you for your help.

[loopoopwert]

Hi, I tried connecting the circuit diagram as shown in the video and it didn't manage to generate any waveform. Could you help in any way??

[MizzardNetNet]

I tried the circuit but it doesn't work!!

I checked everything! Connections, components... everything perfect :(

I'm using the TL072 for now and not LM324... maybe that's why ?

[bakourabdelghani]

Hi please can anyone tell me what is the Range of frequency in this circuit ? !

[wokoteknik]

Excuse me, sir, please give me a solution, how to make a circuit or driver module to replace the CKP and CMP sensors of the inductive type and hall effect type on the car, make a car ECU test simulator.

[ericohman]

How's the low frequency stability with the LM324? Say in the 1-1000 Hz range, does it wobble?