Lm324 Vco

[prprog]

I once had a diagram to built a Voltage Control Oscillator out of a LM324. I dont found it anywhere. I try to google without luck. Anyone got a LM324 VCO circuit and shared it ? Thanks. I will like to built a small synth (music instrument) using such oscillator.

 

[audioguru]

The VCO schematic is on page 13 of the datasheet for the LM324. It uses only 2 of the 4 opamps so an LM358 dual opamp should be used.

 

[ron99999]

Circuit is wrong

The VCO circuit on page 13 of the LM324 app note has an error.
It shows a wire from the last stage's output to the inverting input.
Remove that wire and the circuit will work.

 

[Hero999]

What frequency?

If it's over about 4kHz then forget it.

 

[duffy]

>>The VCO circuit on page 13 of the LM324 app note has an error.
>>It shows a wire from the last stage's output to the inverting input.


Look again. That wire's not connected that way. It's a separate output.
https://www.electro-tech-online.com/custompdfs/2009/01/LM124.pdf

And the LM324 sucks. I wouldn't let my dog use it.

 

[audioguru]

The VCO circuit on page 13 of the LM324 app note has an error.
It shows a wire from the last stage's output to the inverting input.
Remove that wire and the circuit will work.

It doesn't have the wire.

 

[ron99999]

324 Vco

Looks like they caught the error and corrected it. My printed 1995 databook has the bogus extra connection.

 

[audioguru]

The National Semi's databook for the LM833 dual opamp shows a schematic of a 3rd-order lowpass filter with a resistor value completely wrong.

 

[duffy]

I've caught a few mistakes on data sheets, too. They are far from perfect.

 

[audioguru]

I wonder why they hire noobs straight from school or let their receptionist do their datasheets?

 

[duffy]

My money's on the receptionist. I don't think an actual engineer looked at some of these. And when that receptionist isn't busy with those datasheets, she types the data into Digikey's parametric search engine.

 

[audioguru]

Toshiba has a datasheet of a 7905 regulator with a protection diode connected backwards.

Japan New Radio "improves" copies of American opamps. They "improved" their copy of the TL07x opamp by making it faster. It oscillated so badly that it was recalled and replaced with a slower one. The bad datasheet has been removed and I wish I kept it with its discloser of the problem.

 

[duffy]

Ever see the "Damn Fast Buffer Amplifier" or the "Black Hole Diode"? Not really mistakes, just datasheet humor.

 

[audioguru]

Years ago I saw the datasheet for the "Damn Fast Somethingorother". It was very fast for the times. At the time my car had a top speed of 70mph flat out and down a steep hill.

 

[duffy]

Had to be that one. Someone was reaching for a superlative, and they had already used "fast", "very fast" and "ultra fast"...

 

[Roff]

Ever see the "Damn Fast Buffer Amplifier" or the "Black Hole Diode"? Not really mistakes, just datasheet humor.

The Damn Fast Buffer from National Semiconductor was also a damned hot buffer.

 

[Mian Tayyab]

Dear, All
I need a stabilizer kitt which with lm324...

Plz send me any one at: tayyab.mian@yahoo.com

Thanks Regards

 

[audioguru]

I need a stabilizer kitt which with lm324...

This thread talks about a voltage controlled oscillator, not whatever you want.
Please make your own thread instead of hyjacking this thread. Please use proper English grammar and spelling.

You posted your e-mail address so millions of SPAMbots will send you lots of SPAM.

 

[Junker_eu]

Who did know the way to count the output frequence of the VCO?Can whom Know that show us a expression? f=?

 

[Roff]

Who did know the way to count the output frequence of the VCO?Can whom Know that show us a expression? f=?

My translation of this is, "Who knows how to calculate the output frequency of the VCO?"

If you make several simplifying assumptions:
1. The comparator op amp (the one on the right) has rail-to-rail output,
2. Vce(sat) of the transistor is zero volts,
3. the transistor has zero storage time,
4. the comparator op amp has zero recovery time from saturation,

then the frequency is

F = 3*Vc/(4*Vcc*R*C) .

This is pretty accurate for low frequencies and high control voltages. For high frequencies, the recovery and storage times become significant. For low control voltages, the Vce(sat) becomes significant. What is considered significant is up to the user.

An LM324 does not have rail-to-rail output. If you use it, the equation could still be calculated, but it would be even more approximate than the one above.