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5 minutes ago, praezis said:

In fact you have. I wonder if you already blew your ICs?

You should connect:
+9V to V+ pins
0V to V- pins
4.5V (TLE2426) to +In pins.
?

Frank

Here is the original schematic that I followed.  Apparently he had it working in this configuration.  What am i missing/doing wrong.  Do I just have the V+ and V- pins swapped?  Sorry, as I stated I am new to this stuff...  Please be easy on me...LOL!

image.thumb.png.1da2112d7cba7c2ab03502b75c11dec6.png

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40 minutes ago, praezis said:

In fact you have. I wonder if you already blew your ICs?

You should connect:
+9V to V+ pins
0V to V- pins
4.5V (TLE2426) to +In pins.
?
...and think about my 2nd question.

Frank

He has not built this schematic yet...he needs the gain because he is probably taking it off a piezo to listen to a watch.  Depending on how it is physically built...it may just be 10s of microvolts.  So, you need a lot of gain.

You are correct about the power pins...lol...I should have caught--I had seen the original schematic and was concentrating on his mod.

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1 hour ago, CWRNH said:

Do I just have the V+ and V- pins swapped?

V+ connects to to pin 7 of the 5534.  V- connects to pin 4 of the 5534.

Same for LT1115.

Ground (your artificial ground) connects to pin 3 of of both opamps of the 5534.  The LT opamp is in unity gain.  The bias resistor connected to pin 3 connects to ground.

 

Edited by LittleWatchShop
fixed error
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43 minutes ago, LittleWatchShop said:

V+ connects to to pin 7 of the 5534.  V- connects to pin 4 of the 5534.

Same for LT1115.

Ground (your artificial ground) connects to pin 3 of of both opamps

 

Are the bypass caps connected properly?  Should they be connected to the artificial ground or v1?

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1 hour ago, CWRNH said:

Please be easy on me...LOL!

I will ? .
Did not see that you just rebuild the design. So my question goes to the designer.

51 minutes ago, LittleWatchShop said:

he needs the gain because he is probably taking it off a piezo to listen to a watch.  Depending on how it is physically built...it may just be 10s of microvolts.  So, you need a lot of gain.

According my experience and many measurements, a piezo pickup produces 50...100 µV from the most quiet watches, upto 10 mV and more from pocket and loud wrist watches. Then compare it to the level that a mic input can handle (usually << 100 mV).

Frank

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3 minutes ago, praezis said:

I will ? .
Did not see that you just rebuild the design. So my question goes to the designer.

According my experience and many measurements, a piezo pickup produces 50...100 µV from the most quiet watches, upto 10 mV and more from pocket and loud wrist watches. Then compare it to the level that a mic input can handle (usually << 100 mV).

Frank

Does the circuit look correct now? image.thumb.png.e52a232bfc704862374e422ec4ee1a92.png

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11 minutes ago, praezis said:

According my experience and many measurements, a piezo pickup produces 50...100 µV from the most quiet watches, upto 10 mV and more from pocket and loud wrist watches. Then compare it to the level that a mic input can handle (usually << 100 mV).

I don't doubt your numbers, but I think it all depends on how he builds the sensor (microphone).  If it is clipping, he can reduce the gain in the last amplifier (and adjusting caps accordingly).

 

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You drew this in Tina?  Does Tina generate a spice netlist?  You should generate a netlist and then simulate your circuit in LTSpice.  This will both confirm your design and let you see the peak gain and bandpass characteristic. 

Better yet, I would have drawn it in LTSpice so that everything is all in one place.  You are not linking your schematic to your layout, so the schematic tool really does not matter from that perspective.

I am attaching an LTSpice file I generated when I first started reading this thread.  It uses generic opamps, but the library has the LT opamp.  You will have to punt for the other two components, or go find a model on the web.

Watch amplifier_b.asc

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1 hour ago, LittleWatchShop said:

You drew this in Tina?  Does Tina generate a spice netlist?  You should generate a netlist and then simulate your circuit in LTSpice.  This will both confirm your design and let you see the peak gain and bandpass characteristic. 

Better yet, I would have drawn it in LTSpice so that everything is all in one place.  You are not linking your schematic to your layout, so the schematic tool really does not matter from that perspective.

I am attaching an LTSpice file I generated when I first started reading this thread.  It uses generic opamps, but the library has the LT opamp.  You will have to punt for the other two components, or go find a model on the web.

Watch amplifier_b.asc 2.82 kB · 0 downloads

Here is the netlist exported from TINA

UPDATEDOPAMP.CIR

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1 hour ago, LittleWatchShop said:

You drew this in Tina?  Does Tina generate a spice netlist?  You should generate a netlist and then simulate your circuit in LTSpice.  This will both confirm your design and let you see the peak gain and bandpass characteristic. 

Better yet, I would have drawn it in LTSpice so that everything is all in one place.  You are not linking your schematic to your layout, so the schematic tool really does not matter from that perspective.

I am attaching an LTSpice file I generated when I first started reading this thread.  It uses generic opamps, but the library has the LT opamp.  You will have to punt for the other two components, or go find a model on the web.

Watch amplifier_b.asc 2.82 kB · 0 downloads

Here is a sim from TINA, I will draw the whole thing over in LTSpice later and post everything so everyone can enjoy my pain...

sim.tdr

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23 minutes ago, xyzzy said:

If this is connected to an ADC, and one can apply any filter they wanted digitally after that, is there a need for the analog filter stages?

You are correct...in general.  In this case, I don't think @cwrnh has control of the software.

If one were to, say, implement a timer with an Arduino, pre-filtering would make the task easier.

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1 hour ago, LittleWatchShop said:

Here is the simulation of your netlist

 

2021-02-08 15_15_34-LTspice XVII - UPDATEDOPAMP_LTSPICE.CIR.png

So here is an updated TINA schematic with some values changed and two resistors added.  And The new PCB layout to match.  Also attached the netlist.  I am working on the Ltspice schematic now.  I have LtSpice and have used it but like TINA better. (Probably because I am new to all this).  I will import the components and spice models and post the new drawing when finished.image.thumb.png.ca65d82f3c3c167308cf59d12858f5da.png

image.thumb.png.ac93238b6985b28cd8a9f684e662a656.png

UPDATEDOPAMP2.CIR

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8 minutes ago, CWRNH said:

Okay, thanks I will try that.

 

I can't figure out what I am doing wrong in LTSpice to simulate the net list.  I guess I have to import the Spice models first.  I keep getting errors.  Have to learn and relearn so much stuff...LOL!

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2 hours ago, xyzzy said:

If this is connected to an ADC, and one can apply any filter they wanted digitally after that, is there a need for the analog filter stages?

This is one of the things that makes this discussion interesting. Everybody has different ideas. It also depends upon what you're connecting it up to as to how much digital filtering capabilities you have. So maybe just an initial filter knocking off everything under 1000 cycles is all you really need. Or maybe just a couple of transistors with no filtering at all.

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  • 2 weeks later...

Hello all, finished reading all posts last night and the first thing I want to say is a thank you, thanks for Stefan and all of the others who contributed. I read the posts with great joy and these posts are the reason why I like this site so much.

The reason why I ended up with this topic is that after about two years, I felt the need to dive a little bit deeper into a watch anatomy, and for that, I needed a stethoscope or using a different name of it: a watch timing machine. A while ago i bought a Weishi Timegrapher NO.1000, but i have not used it much. I tried it once and that's all really. I thought i repair/service a few low cost watches and if it is successful i put them back to eBay, but i figured that probably it would be a good idea to check their performance before i sell them. First of all that would be the fair thing to do, then i would get my money back I spend on them with a tiny bit of profit, while I learn for free. Now some of these old low cost watches would not need a timgrapher because some of them are so bad that the Weishi for example would not even be able to listen to them. However I am climbing up on the ladder and I recently serviced or resurrected a ronda 1217-21 movement in a Services 17 jewels watch, one in such a bad shape that I thought it would be impossible to make it work again before. That movement gives us a nice readable sound and it is full of opportunities for learning including listening to its heartbeat. Earlier i saw a debate what is needed first a microscope or a timing machine, i am not going to give you an answer for that debate, but i am going to tell you that I had both and at the beginning I found the microscope incredibly useful while I did not use the timing machine at all. As a beginner the only thing what mattered for me that the watch was ticking at the end after the cleaning / servicing and re-assembling/lubricating process. At the beginning I ruined them permanently more often than not so there was no need to check the performance of a dead watch.

Now, I also bought two microphones a while back because I tend to buy things where i see a unique opportunity even though i dont need the subjects in question at the time of buying them. I took a few pictures of one of them where i need to replace the sensor:

IMG_20210217_143220.thumb.jpg.f82d90544df2d7c57b8b32c21bfaf6ef.jpgIMG_20210217_143157.thumb.jpg.0e9d5bc44e411be7a1687ec9b448e4b7.jpgIMG_20210217_143323.thumb.jpg.8862bc7398d3efd895c84fb6b4b40c07.jpgIMG_20210217_143337.thumb.jpg.0618b22af60b71bb384a1996cca3818f.jpgIMG_20210215_115616.thumb.jpg.a13b1fcc4061d74e287457bb2115666e.jpgIMG_20210215_115625.thumb.jpg.0b033feba6dcc6b6b8316fe2d564e68e.jpgIMG_20210217_115421.thumb.jpg.9d9b0aa67da67c85d3429e8e04f583ff.jpg

 

As you can see the sensor is in a really bad shape and need to be replaced, it seems like most of its stuff just evaporated. I assume that John answered this question as why earlier, but I am not sure so I am going to ask a number of questions following this post. My original plan was to use this microphone with open source TG and after that idea I found this topic. First thing first I need to bring this microphone back into life.

You must admit that this microphone has a cool factor. ?

And look at this:

science watch-timers

science watch-timer 2

 

 

Edited by luiazazrambo
correcting English - hopefully
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On 4/21/2020 at 3:07 AM, JohnR725 said:

Then because the originals are water-soluble I'm reasonably sure that they're made of Rochelle salt (sodium potassium tartrate tetrahydrate) It's amazing what you can find on Wikipedia.  So what will happen with time is They will absorb moisture and just disintegrate.

@JohnR725 Is this the reason why my sensor looks like that above?

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