Regarding 10KHz Oscillator
Hi Frex,
I made oscillator based on your schematics and assembled boards.
I got the oscillation at 10Khz... But amplitude seems to be unstable.. It goes to 7Vpp and comeback to 4Vpp and goes to 3.8Vpp and so on so forth..
I followed LT app note to tune the circuit.
Can you let me know how to tune the circuit?
With Regards,
AK
Hi Frex,
I made oscillator based on your schematics and assembled boards.
I got the oscillation at 10Khz... But amplitude seems to be unstable.. It goes to 7Vpp and comeback to 4Vpp and goes to 3.8Vpp and so on so forth..
I followed LT app note to tune the circuit.
Can you let me know how to tune the circuit?
With Regards,
AK
As the Hobbits would have put it - your hat starts to be to big for your head...
This is diy or maybe your oscillators better fits in the vendors section? Sorry for being harsh...
Regards and thank you for the AN that is free!
Hi Frex,
I thought we are all belong to community that's the reason I asked....anyway thanks... Coz app note settings procedure seems to be wrong..if you share it it will be of great help...if it's ok, I am ready to buy one Pcb from you.
Pls let me know.
With Regards,
AK
Yeah, my answer was maybe a bit awkward...I apologize...
AK, you find the document about adjustment the oscillator below :
EOSC10KV2_Manual
Frex
AK, you find the document about adjustment the oscillator below :
EOSC10KV2_Manual
Frex
Sorry to say there are others as well digging and looking for what we might pay for and making financial estimates, hagging with producers to maximate profits. I do understand that in this environment - why shouldn't you Frex? I cincerely think your and victors doesn't fit in this forum anymore. Then we have the others that just talk an give nilch - they just can't count. Their constructions are probably priceless. Cudos to you Frex, pmillet, agdr and all who understood what this forum is about. Today it has turned to a hagging place where everything has a price.
Hi Turbon,
I disagree completely. I bought boards from Frex and I'm very grateful that I could. Otherwise, I wouldn't be able to afford an oscillator such as this. Once I have completed them, they will be well used. I needed exactly something like this. Now I need an analyzer that will show me what is going on "down there". Having this clean a source is the main thing.
The cost of the parts exceeded the PCBs, and not by a little bit either. The board pricing is probably fair (I wouldn't know), and Frex had to put the money and effort out by himself. This is exactly the right place for this thread.
Frex, many thanks for all your hard work. Just in case you might feel it is not appreciated.
-Chris
I disagree completely. I bought boards from Frex and I'm very grateful that I could. Otherwise, I wouldn't be able to afford an oscillator such as this. Once I have completed them, they will be well used. I needed exactly something like this. Now I need an analyzer that will show me what is going on "down there". Having this clean a source is the main thing.
The cost of the parts exceeded the PCBs, and not by a little bit either. The board pricing is probably fair (I wouldn't know), and Frex had to put the money and effort out by himself. This is exactly the right place for this thread.
Frex, many thanks for all your hard work. Just in case you might feel it is not appreciated.
-Chris
Hi Frex,
Thanks for the beautiful write up.. It's different than that of in the app note..l got it working as per your tuning procedure...I measured around -138dB THD at 10KHz..
Will buy from you to verify as well..
Thanks,
AK
Regarding Oscillator
Hi Frex,
couple of questions regrading the oscillator tuning..
1. One of my outputs of the oscillator is oscillating at very high frequency.. 1.16MHz on couple of boards after power up..... Sometimes if I tune one more time it will go away. Do you have nay clue?
Basically 1.16MHz is riding on my 10Khz output.. Other output is always stable.
With Regards,
AKHILESH K
Hi Frex,
couple of questions regrading the oscillator tuning..
1. One of my outputs of the oscillator is oscillating at very high frequency.. 1.16MHz on couple of boards after power up..... Sometimes if I tune one more time it will go away. Do you have nay clue?
Basically 1.16MHz is riding on my 10Khz output.. Other output is always stable.
With Regards,
AKHILESH K
Hello akhi,
I'm back from holidays that explain my answer delay.
About your own AN67 PCB design :
The oscillator use very high gain blocks (160dB@10kHz !)
and such gain can produce unexpected behaviour or HF oscillations if parts placement,
PCB traces routing and selected passives parts are wrong.
You must keep in mind that LT1229 is current feedback type OPAMP and gain-bandwidth
product is very high. They don't work same as classic voltage-feedback OPAMP
and doesn't accepts any FB capacitance for example.
So, you must check your own PCB design carefully.
Note that those are precisely on these points i had worked much to provide
an PCB that work fine in all conditions.
To help you more, post here your PCB drawing and schematics.
Frex
I'm back from holidays that explain my answer delay.
About your own AN67 PCB design :
The oscillator use very high gain blocks (160dB@10kHz !)
and such gain can produce unexpected behaviour or HF oscillations if parts placement,
PCB traces routing and selected passives parts are wrong.
You must keep in mind that LT1229 is current feedback type OPAMP and gain-bandwidth
product is very high. They don't work same as classic voltage-feedback OPAMP
and doesn't accepts any FB capacitance for example.
So, you must check your own PCB design carefully.
Note that those are precisely on these points i had worked much to provide
an PCB that work fine in all conditions.
To help you more, post here your PCB drawing and schematics.
Frex
Regarding unwanted oscillation
Hi Frex,
I figured out the issue with oscillation.. Seems like the oscilloscope probe connection to one my outputs causing this trouble. I have used SMA connectors in my design for the outputs. also I connect the board to scope using SMA to BNC cable.
With Regards,
AKHI
Hi Frex,
I figured out the issue with oscillation.. Seems like the oscilloscope probe connection to one my outputs causing this trouble. I have used SMA connectors in my design for the outputs. also I connect the board to scope using SMA to BNC cable.
With Regards,
AKHI
Hello Akhi,
I provide only bare PCB.
The price is 18€ outside EU and 17€ inside EU.
If you want buy one, just send me your personal email address by PM
and then i will send you a Paypal invoice.
Yes, sometimes a scope probe itself can suffice to cause oscillation.
This is particularly true when using x1 probe that have much higher capacitance
than x10 or even x100 probe. Happy to know that you have fixed this !
By the way, SMA as also a good option as output connector.
Regards.
Frex
I provide only bare PCB.
The price is 18€ outside EU and 17€ inside EU.
If you want buy one, just send me your personal email address by PM
and then i will send you a Paypal invoice.
Yes, sometimes a scope probe itself can suffice to cause oscillation.
This is particularly true when using x1 probe that have much higher capacitance
than x10 or even x100 probe. Happy to know that you have fixed this !
By the way, SMA as also a good option as output connector.
Regards.
Frex
Buying Bare PCB
Hi,
my Email ID is akhi9980@gmail.com.
pls send me paypal invoice for the same.
With Regards,
AKHILESH K
Hi,
my Email ID is akhi9980@gmail.com.
pls send me paypal invoice for the same.
With Regards,
AKHILESH K
So all the bits arrived and I've built this beast.
It's rather remarkable. After quickly setting the loop gain, I set the output level to 5.0V RMS (+27.0dBm on my HP3585B spec-an). Then I put a 1KHz notch between the spec-an and the oscillator. My 1KHz tone now measures -28.6dBm, so my notch is working passingly well and giving me 55.6dB depth at the fundamental.
Then I wound the range down to -25dBm full-scale (the limit of the analyser). No over-range indicator, so that's promising. I went looking for harmonics with 3dB resolution bandwidth and found really tiny humps just above the noise floor, measuring -126.6dBm at 2KHz, -124.0 at 3KHz, and -133.5dBm at 4KHz. Everything else was masked by the -140dBm noise floor of the instrument.
After applying a fudge factor for my notch, I make that -144.4dBc for H2, -145.5dBc for H3, -156.7dBc for H4, and <-164dBc for higher order harmonics.
Wow.
I'm not completely certain those harmonics aren't being generated in the analyser, either, as the fundamental was pretty close to the -25dBm full-scale at lowest range after applying the notch. I'll need to build a better notch to know for sure.
It's rather remarkable. After quickly setting the loop gain, I set the output level to 5.0V RMS (+27.0dBm on my HP3585B spec-an). Then I put a 1KHz notch between the spec-an and the oscillator. My 1KHz tone now measures -28.6dBm, so my notch is working passingly well and giving me 55.6dB depth at the fundamental.
Then I wound the range down to -25dBm full-scale (the limit of the analyser). No over-range indicator, so that's promising. I went looking for harmonics with 3dB resolution bandwidth and found really tiny humps just above the noise floor, measuring -126.6dBm at 2KHz, -124.0 at 3KHz, and -133.5dBm at 4KHz. Everything else was masked by the -140dBm noise floor of the instrument.
After applying a fudge factor for my notch, I make that -144.4dBc for H2, -145.5dBc for H3, -156.7dBc for H4, and <-164dBc for higher order harmonics.
Wow.
I'm not completely certain those harmonics aren't being generated in the analyser, either, as the fundamental was pretty close to the -25dBm full-scale at lowest range after applying the notch. I'll need to build a better notch to know for sure.