100KHz sine wave osc.

[PratapKollu]

Dear Sir
I need a pure 100 KHz sine wave with an amplitude of 10v, I tried the wein bridge oscillator but I cant get pure sinewave that can drive a sensor,
Is there any commercial oscillator IC for 100 Khz sine wave.? or any alternative solutions for my problems?
Comments and critiques are welcome

Thanks and Regards
Pratap
pratapkollu@yahoo.com

 

[akg]

an osc with TTL NOT gates and Xtal

 

[Nigel Goodwin]

an osc with TTL NOT gates and Xtal

That outputs a square wave, NOT a pure sinewave.

However, he already knows the answer, 'a wein bridge oscillator' - if it can't drive the sensor then it's not designed correctly, but as he hasn't given any specs for it we've no idea what it's output capabilities need to be?. But basically, add an amplifier to the output so it can drive the load.

 

[akg]

oops.. sorry .. i misread
i read it 100KHz sq wave osc.

 

[PratapKollu]

That outputs a square wave, NOT a pure sinewave.

However, he already knows the answer, 'a wein bridge oscillator' - if it can't drive the sensor then it's not designed correctly, but as he hasn't given any specs for it we've no idea what it's output capabilities need to be?. But basically, add an amplifier to the output so it can drive the load.

Dear Nigel Goodwin,
The oscillaotor circuit is amplitude limiting wein bidge ocs. Op amp used is TL082, RC circuit has a resistor of 1k ohm and capacitor of 1.5nF.
IS this information enough?
Thank you
Pratap

 

[Papabravo]

Dear Nigel Goodwin,
...
IS this information enough?
Pratap

It is a start, but we really need to see a schematic diagram. It is entirely possible that there is an error in the schematic, or perhaps a wiring mistake which will be obvious if we can see the same thing you are looking at.

I'm assuming here that neither astral projection, nor remote viewing is a realistic possibility.

 

[PratapKollu]

It is a start, but we really need to see a schematic diagram. It is entirely possible that there is an error in the schematic, or perhaps a wiring mistake which will be obvious if we can see the same thing you are looking at.

I'm assuming here that neither astral projection, nor remote viewing is a realistic possibility.

Here is the circuit diagram, please go through it. I am using the precison potentiomenter
Thank you
Pratap

 

[Nigel Goodwin]

Dear Nigel Goodwin,
The oscillaotor circuit is amplitude limiting wein bidge ocs. Op amp used is TL082, RC circuit has a resistor of 1k ohm and capacitor of 1.5nF.
IS this information enough?

Not really, what problem are you having with it?, what are you trying to feed?, and is it OK if you don't connect the load?.

I would also prefer to see some kind of gain control?, what are you wanting it for?, 100KHz is the standard frequency for ESR measurements.

 

[PratapKollu]

Not really, what problem are you having with it?, what are you trying to feed?, and is it OK if you don't connect the load?.

I would also prefer to see some kind of gain control?, what are you wanting it for?, 100KHz is the standard frequency for ESR measurements.

I am driving a sensor circuit using this 100KHz sine wave, when I check the DC ouput of my signal, there is a lot of noise in it, but when I remove this wein bridge oscillator and connect the HP synthesizer(100 KHz, 10V, the same signal as wein bridge oscillator), the output is fairly good free from noise.
I feel there is some problem with the stability of the wein bridge oscillator either in the frequency or amplitude.
Are there any commercial ICs that produce 100KHZ sine wave?
Thank you
Pratap

 

[Nigel Goodwin]

What is the load impedance that the sensor presents to the oscillator?, as your circuit is it requires a fairly high impedance load. If the sensor is a low impedance then you need a buffer (or amplifier) between the oscillator and your sensor. Bear in mind your HP already includes an amplifier/buffer, and has a low impedance, fairly high power, output.

 

[audioguru]

The amplitude-limiting diodes cause distortion by "flat-topping" the waves.
Maybe the detector circuit needs the peak of a sine-wave for accurate timing. Waves with flat tops don't have accurate peaks.
Maybe the amplitude is set too low.

 

[Papabravo]

I'm assuming that Vcc is some positive voltage above GND and Vdd is some nagative voltage below GND. Is this correct?

I see no power supply decoupling capacitors. They are often omitted from design schematics but in most cases they should be there, especially if the noise is conducted from the power supply directly to the output. What kind of a supply do you have?

Your amplifier is labeled U1-B. What is the other opamp in the package doing. Did you leave its high impedance inputs floating so they could oscillate like a screeming banshee? Tch-Tch!

See how helpful that schematic was? Isn't that amazing?
Grinning broadly.

 

[Analog]

For pure sine waves, I always use a double integrator with an inverting follower. The poles will always fall directly on the imaginary axis, yielding a pure sinewave. Theoretically, you can't get anything more pure than poles on the j axis. That may be worth a try, it will take 3 op amps..

 

[Papabravo]

I just get shivers when people talk about complex numbers and the j-omega axis!

 

[audioguru]

... like a screeming banshee?.

LOL
My noisy neighbour has one. It make a racket.

 

[Russlk]

The Hewlett-Packard 200CD used a lamp for amplitude regulation, perhaps you could use that circuit.

 

[Nigel Goodwin]

OK, here's a 100KHz wein bridge oscillator, it's out of an ESR meter I built a number of years ago, the bulb is a wire ended one, 28V 24mA. Obviously for your requirements you would just take the output from the output of the opamp.

But as I mentioned previously, you need to be aware of the load requirements of your sensor, and may well need an amplifier to follow it?.