EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Hugoneus on September 04, 2017, 03:55:01 am
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There are some neat experiments in this tutorial which I hope you like.
You can watch it here: [49 Minutes]
youtu.be/rzzliN_vTKs (http://youtu.be/rzzliN_vTKs)
More videos at The Signal Path:
www.TheSignalPath.com (http://www.TheSignalPath.com)
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"And here I'm using centimeters, because I'm not insane" - awesome!!!
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I enjoyed this one because I understood what you were doing and how you were doing it. Which isn't usually the case :o
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Brought back bad memorys from a lecture at university about some really difficult stuff, that I coudnt link to anything.
Now I can and learning it then will look much more usefull/easier now, since now it has a known purpose, other than just "youll see later whats its good for".
Sent from my A0001 using Tapatalk
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Very nice and informative video.
Thank you!
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Thanks for the video. Very informative. I had no idea something like this even existed :-+
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Thanks for the video. Very informative. I had no idea something like this even existed :-+
Glad you liked it.
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A lockin is a really powerful instrument. The two experiments are really nice. However the time constant at the Lockin is chosen rather long - thus a sluggisch response. It could have been done with faster response - despite of increasing noise.
It might have been interesting to also look at the monitor output for the second experiment. This might have even replaced the measurement with the DMM.
The SR530 is still a classical analog one. Modern Lockins usually do much of the operation in digital - so the block diagram looks different. I am somewhat surprised the SR530 did not include an internal function generator. Usually there also is a simple generator included.
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Great video!
I've had the pleasure of calibrating many of these units :popcorn: They are a great unit to work with!
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Oh cool - I used these in the IR lab where I worked before I retired. Nice piece of gear. :-+
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A lockin is a really powerful instrument. The two experiments are really nice. However the time constant at the Lockin is chosen rather long - thus a sluggisch response. It could have been done with faster response - despite of increasing noise.
It might have been interesting to also look at the monitor output for the second experiment. This might have even replaced the measurement with the DMM.
The SR530 is still a classical analog one. Modern Lockins usually do much of the operation in digital - so the block diagram looks different. I am somewhat surprised the SR530 did not include an internal function generator. Usually there also is a simple generator included.
It does have an internal oscillator! I just didn't use it to avoid causing confusion. The internal source is accessible from the back.
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If one has time, one can really go down in bandwidth and this way down in noise. I have once used a similar lockin with additional external digital integration over 1000 seconds to look at a really small signal. It just took a weekend to get a curve. Using digital integration (e.g. reading via GPIB) can cut down on the waiting time for the signal to stabilize, so less time is lost.
For an experiment like the laser - LED one, the better mode is to use just one channel and adjust the phase before. Using the amplitude / phase modes is kind of easy to use, but gives slightly higher noise. So this experiment could also be done with a simpler single channel version if the lockin. The dual phase version has very little advantage in this case.
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Awesome video. Is there a schematic available for this instrument?
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Looking for the schematic myself. I have a big error in the current gain (around 20-30%) but voltage gain is fine (a few percent error at most). The description from the manual states -
<<When the input selector is set to current, the input to the pre-amp comes from the output of the current to voltage converter, 1/2 U102. U102 is a low voltage-noise bipolar op amp. Q102 serves as an input buffer to provide low current-noise to the input. The op amp always maintains a null at the gates of Q102 thus providing an input impedance of 1KΩ (R128). The input current is converted to a voltage by R135 and the op amp. Q103 bootstraps out the summing junction capacitance of Q102.>>
Seems like the 1kohm is a terminating impedance and input current is buffered by an N ch FET and sent to a TIA with a feedback gain of 1e6 (R135). I'll open it up and see if I can find out what's going on.
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This documents included the schematic of the SR510, which should be fairly similar. Not the best scan, but better than no schematics...
Had to split the zip in 4 parts to attach it here. Files named Lockinamplifier_SR510.z0x.zip need to be renamed to Lockinamplifier_SR510.z0x to unzip (forum only allows to attach zip files)
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This documents included the schematic of the SR510, which should be fairly similar. Not the best scan, but better than no schematics...
Had to split the zip in 4 parts to attach it here. Files named Lockinamplifier_SR510.z0x.zip need to be renamed to Lockinamplifier_SR510.z0x to unzip (forum only allows to attach zip files)
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This documents included the schematic of the SR510, which should be fairly similar. Not the best scan, but better than no schematics...
Had to split the zip in 4 parts to attach it here. Files named Lockinamplifier_SR510.z0x.zip need to be renamed to Lockinamplifier_SR510.z0x to unzip (forum only allows to attach zip files)
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This documents included the schematic of the SR510, which should be fairly similar. Not the best scan, but better than no schematics...
Had to split the zip in 4 parts to attach it here. Files named Lockinamplifier_SR510.z0x.zip need to be renamed to Lockinamplifier_SR510.z0x to unzip (forum only allows to attach zip files)
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Unfortunately page 82 which contained the input section was not in good shape. Some reverse engineering is in order :)
The rest of the schematics are good. Thanks.
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Unfortunately page 82 which contained the input section was not in good shape. Some reverse engineering is in order :)
The rest of the schematics are good. Thanks.
I does seem that once upon a time these were delivered together with the unit in a printed format. Did you already ask SRS for a copy? I had good luck with Signal Recovery (Ametek) in the past
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Got one of these but by the looks of it the LCD is all over the shop (analog meter seems fine). If anyone is looking for a project to outdo The Signal Path: feel free to drop me a PM ;-)
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Unfortunately page 82 which contained the input section was not in good shape. Some reverse engineering is in order :)
The rest of the schematics are good. Thanks.
I does seem that once upon a time these were delivered together with the unit in a printed format. Did you already ask SRS for a copy? I had good luck with Signal Recovery (Ametek) in the past
I contacted SRS and they suggested to buy hard copy from outside vendors for about $100.
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I couldn't find a printed SR530 manual, but found SR830. Here is the page with the input amplifier. Perhaps it is similar enough.
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The SR830 input stage is more conventional. The current to voltage converter uses just a single OP-amp.