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Preamp questions


Ammar

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Hello,

I tried Watch-o-scope and Tg programs when I started out this hobby but I got no results and I just decided to spend a week timing the few watches I service bu yesterday I say Jd Richard's video on time graph softwares and tried trickoprint on my phone whic worked fine and gave me a reading, I don't know if it's accurate or not but I was really happy to see a reading anyway.

after that I did some research with the help of uncle Google and I found that to get better results I have to get myself a Preamp  which I didn't even know such a thing existed :woohoo-jumping-smiley-emoticon:.

anyway I found a couple of really cheap preamps and I am almost certain that they wont work just because it's me and I never get stuff easy but I decided to ask for advice from you nice people.

this is the first one (no specifications):

arduino-pam8403-mini-digital-amplifier-board-2x-3w-2-kanal-5v__1167810222652033.thumb.jpg.4f4ca9cb36f7ee7949a5ae9e9e9392dc.jpg

 

and this is the other one which they have the specifications for:

arduino-pam8403-mini-digital-amplifier__1525545752135368.thumb.jpg.7a3b84930e90cb9ba80dba9f2716f7f7.jpgarduino-pam8403-mini-digital-amplifier__1072380814283852.png.ca957553aac570dcda9910241d703249.png

From what I have read I should use a Piezo mic with these which is available as well.

please note that I know very little about electronics I just have a soldering iron and a cheap multi meter, also it's not like I don't want to buy a proper timegrapher but I can't afford spending 200$ as I have been unemployed for a long time and even when I was working I was getting paid like 300$ a month but I would have managed to save up.

Thank you and have a nice day.

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Hi Ammar,  I take it no luck with the watches I sent, Probable binned  by the customs house . 

Either of those pre amps will work, The one with the switch/volume control will be better as there is less work to do But heed the warning about polarity as you could fry the board. The piezo mich will work ok .  I am surprised that you had no luck with watch-o-scope I have it on my laptop and build the pickup and the amplifier as instructed and it works very well, At the moment I use the lite version as a backup to my Horometer unit  and it works very well. There are several bits of watch timing apps for the i phone I have a few of them, the one JD previewed lookd very good.           Take care and be safe 

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Hey! Something I know a little about for a change! To start, it's a little confusing, because the first and second pictures are not the same board. They do appear to be using the same chip, so consider the following:

An audio pre-amp takes a low powered signal (like from a microphone) and makes it bigger so that a larger amplifier can take over and put it to speakers. In your case, the larger amplifier is in your computer/tablet/phone.

That particular device (first image), assuming the screen printing is to be trusted, wants 5V, which is right about what you get from a USB port. You could also very easily find a 5V DC wall wart at Mauser/DigiKey (or Turkey's equivalent if that's not an option), and run it off that if it helps declutter. They edited out the chip screening, but I'd bet money it's a bunch of op-amps ganged up into a single package. I know that probably means nothing, but essentially it's likely a bunch of even smaller amplifiers all in a line to make a larger amplifier. 

Once you have either broken out the power leads from a USB cable or a DC power supply, the bottom left is where you'd put the Left and Right outputs from your microphone setup. You probably won't be using a stereo microphone, so you can either pick one, or run it to both. To get it to your device, you run the audio plug to the L/R channels at the top of the board. 

The larger board with the green thing and the knob looks like it's essentially the same thing, but it gives you the option of a power/volume knob. If you follow the above instructions using the printed labels rather than spatial description, you'll get essentially the same result.

That's how... The question though is whether or not it'll get you there. If that board were dropped into my lap, and I was told to use it to make a microphone work on a device, that's how I'd do it. I can't say for sure that's the exact correct device for the job, but the fact that it is likely marketed as an audio preamplifier is promising. If it's only a few bucks, I say jump. It'll likely get you where you're going. 

The one caveat I see is that in some of the results I'm finding, the pictures show the outputs going directly to speakers. 3W isn't huge, but it may be more than your device wants. This could either mean you're better off with a different chip or at least the one with the knob so you can turn it down.

 

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7 hours ago, watchweasol said:

Hi Ammar,  I take it no luck with the watches I sent, Probable binned  by the customs house . 

Either of those pre amps will work, The one with the switch/volume control will be better as there is less work to do But heed the warning about polarity as you could fry the board. The piezo mich will work ok .  I am surprised that you had no luck with watch-o-scope I have it on my laptop and build the pickup and the amplifier as instructed and it works very well, At the moment I use the lite version as a backup to my Horometer unit  and it works very well. There are several bits of watch timing apps for the i phone I have a few of them, the one JD previewed lookd very good.           Take care and be safe 

Hi,

yes looks like the got stuck at the customs for some reason, I contacted them and they told me that they would contact me if there's something coming my way the guy didn't even bother looking them up customs are like this sometimes, I didn't want to bother you with more messages so I figured I'll send a message if they arrive.

I think watch-o-scope didn't work for me because of the crappy mic I was using I hope I cant fix this issue with these circuits.

I got my self a Seiko 7009 and I can't wait to start working on it, it seems to be in a good condition and just needs some love because the balance wheel is running a bit slow, it's keeping a good time though which I don't understand why tbh.

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1 hour ago, spectre6000 said:

Hey! Something I know a little about for a change! To start, it's a little confusing, because the first and second pictures are not the same board. They do appear to be using the same chip, so consider the following:

An audio pre-amp takes a low powered signal (like from a microphone) and makes it bigger so that a larger amplifier can take over and put it to speakers. In your case, the larger amplifier is in your computer/tablet/phone.

That particular device (first image), assuming the screen printing is to be trusted, wants 5V, which is right about what you get from a USB port. You could also very easily find a 5V DC wall wart at Mauser/DigiKey (or Turkey's equivalent if that's not an option), and run it off that if it helps declutter. They edited out the chip screening, but I'd bet money it's a bunch of op-amps ganged up into a single package. I know that probably means nothing, but essentially it's likely a bunch of even smaller amplifiers all in a line to make a larger amplifier. 

Once you have either broken out the power leads from a USB cable or a DC power supply, the bottom left is where you'd put the Left and Right outputs from your microphone setup. You probably won't be using a stereo microphone, so you can either pick one, or run it to both. To get it to your device, you run the audio plug to the L/R channels at the top of the board. 

The larger board with the green thing and the knob looks like it's essentially the same thing, but it gives you the option of a power/volume knob. If you follow the above instructions using the printed labels rather than spatial description, you'll get essentially the same result.

That's how... The question though is whether or not it'll get you there. If that board were dropped into my lap, and I was told to use it to make a microphone work on a device, that's how I'd do it. I can't say for sure that's the exact correct device for the job, but the fact that it is likely marketed as an audio preamplifier is promising. If it's only a few bucks, I say jump. It'll likely get you where you're going. 

The one caveat I see is that in some of the results I'm finding, the pictures show the outputs going directly to speakers. 3W isn't huge, but it may be more than your device wants. This could either mean you're better off with a different chip or at least the one with the knob so you can turn it down.

 

Thank you for the explanation, I found some better photos from another seller if that gives you more information, now I don't want to mess this up as I usually tend to do let me tell you what I understand:

so the r-out l-out are basically where the speakers are connected but in my case it's where I connect the cable with the 3.5 mm jack going to the pc/phone.

The 5 volts is the easiest part I can connect it to usb or 5 v wall adapter as you mentioned but I read somewhere that it would cause some humming or noise and it's better to use batteries but it looks like 5 v batteries don't exist.

The input side is where I connect the mic and this is where I'm confused because there are 3 connection points and no polarity and the mic has only two wires and what exactly does (L,G,R) stand for.

Thank you very much for helping me.111.thumb.jpg.55600a3e3926a22d4f0e51f82c3e6849.jpg222.thumb.jpg.6132dcf854a96e24fc169e5fd5bba311.jpg

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4 hours ago, Ammar said:

so the r-out l-out are basically where the speakers are connected but in my case it's where I connect the cable with the 3.5 mm jack going to the pc/phone.

Correct.

Quote

The 5 volts is the easiest part I can connect it to usb or 5 v wall adapter as you mentioned but I read somewhere that it would cause some humming or noise and it's better to use batteries but it looks like 5 v batteries don't exist.

So... The hum they're referring to is the AC cycling polarity... In the US, it's 60 Hz and sounds like a low hum. I have no idea what the AC frequency is in Turkey though... If you're playing an electric guitar with a lot of distortion or a hifi audio system at high volume, yeah, it sucks. I doubt this will come through in a way that would affect a watch analyzing program. If you want to play it safe though, power it via USB. That uses your laptop/phone battery, and the AC cycling is fully out of the picture. I seriously doubt a quality power supply would give you any issues though, and it's less trouble to wire up if you don't know the pins on a USB plug. 

Quote

The input side is where I connect the mic and this is where I'm confused because there are 3 connection points and no polarity and the mic has only two wires and what exactly does (L,G,R) stand for.

L is Left channel, G is Ground, R is Right channel. You microphone has a signal (center) and ground wire (green or jacket). You can either pick a channel, or run the signal wire to both. If you go to just the one channel, and the software is only listening on one, you have a 50/50 shot of success, but it would get 100% of the signal if you guessed right. You could get around this by wiring the stereo output in a mono fashion (I think that still works with modern audio...). If you run it to both AND the software is listening on both channels, you effectively get double the output from the amplifier. 

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9 hours ago, spectre6000 said:

Correct.

So... The hum they're referring to is the AC cycling polarity... In the US, it's 60 Hz and sounds like a low hum. I have no idea what the AC frequency is in Turkey though... If you're playing an electric guitar with a lot of distortion or a hifi audio system at high volume, yeah, it sucks. I doubt this will come through in a way that would affect a watch analyzing program. If you want to play it safe though, power it via USB. That uses your laptop/phone battery, and the AC cycling is fully out of the picture. I seriously doubt a quality power supply would give you any issues though, and it's less trouble to wire up if you don't know the pins on a USB plug. 

L is Left channel, G is Ground, R is Right channel. You microphone has a signal (center) and ground wire (green or jacket). You can either pick a channel, or run the signal wire to both. If you go to just the one channel, and the software is only listening on one, you have a 50/50 shot of success, but it would get 100% of the signal if you guessed right. You could get around this by wiring the stereo output in a mono fashion (I think that still works with modern audio...). If you run it to both AND the software is listening on both channels, you effectively get double the output from the amplifier. 

Sounds straightforward I'm gonna order this chip and see what happens I'll never know unless I try these things are really cheap to my surprise.

I found this Piezo Mic with this small chip but I have no idea what this is and what does it do, do you think I need to get it with the Piezo or it's no required for my little project seramik-piezo-titresim-sensoru__1174116611590828.thumb.jpg.75082df1cdc73639f434eda5d7ce2f02.jpg

and this is the description of it as posted by the seller (translated it on Google because I don't know the Turkish terminology of electronics):

Working Voltage: 3.3 V or 5 V

Working Current: <1mA

Working Temperature Range: -10 ~ + 70

Interface Type: Analog Output

Product Size: 30mm x 23mm

GPIO: S; signal output, +; power supply (VCC), -; ground (GND)

Introduction: Positive electrode piezoelectric ceramic

Gnd: Negative electrode piezoelectric ceramic

S-point with connected controller's analog input pin

5 V and GND respectively connected to the power supply + 5 V and GND

Already piezoelectric ceramics associated with the inlet and Gnd 'positive and negative.

Thank you.

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9 hours ago, rodabod said:

It would be handy to know what the input impedance is a piezo transducers are high-Z (often around 10K Ohm). The data sheet for the chip may say. 

To be completely Honest I have no idea what this means, but in case you mean the chip on the circuit I found this data sheet online.

https://www.diodes.com/assets/Datasheets/PAM8403.pdf

and this is the circuit description:

Mini 5V PAM8403 Audio Power Amplifier Module Board 2 Channel With Volume Control


Features:

PAM8403 is a small digital amplifier chip, high-definition sound highlights the advantages of digital chips

The circuit uses the most reasonable peripheral configuration, power supply filter is upgraded to 470uf

1.6mm glass sheet, the real power amplifier board to do the most meticulous, the output 3W +3 W high-fidelity sound quality,

Amplifier enthusiasts rare good products, potentiometer using the original anti-body,

Potentiometer with switch reversible clock can be directly cut off the power supply

Power supply range: 2.5-5.5V

Minimum output: 2x3W (5V 4?)

Dimensions: 29.5 * 20.2 * 15mm

 

Thank you

Edited by Ammar
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3 minutes ago, Ammar said:

To be completely Honest I have no idea what this means, but in case you mean the chip on the circuit I found this data sheet online.

https://www.diodes.com/assets/Datasheets/PAM8403.pdf

Thank you

It doesn’t mention on the data sheet. Incidentally, this is really a power amp for driving a loudspeaker, but I expect that it will work acceptably at low gains. 
 

Something like a phono preamp may be more suitable, especially if you were able to modify it to remove any equalisation:

 

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F324015246773 

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Disclaimer: I'm not an electrical engineer, I only play one on TV.

Looking deeper, I think rodabod may be right. That does look like a higher output amplifier than you'd typically want for a preamp. 3W per channel sounds small to me, but my amplifiers are all quite large by comparison and not pushing little computer speakers or whatever. That's not to say this necessarily won't work, but it might want a larger signal to start than the mic puts out on its own, and could put out more volume than the software knows what to do with. A phono preamp is the exact thing you're most likely looking for, and should play nice with most microphones.

As for the piezo microphone, it looks like it'd play nice on the power side, but the output isn't mentioned (nor are the signal input ranges mentioned on the amplifier).

https://www.sparkfun.com/products/12758

These guys are local to me. Good people, good products. This is your microphone and preamp all matched, soldered, and ready to go. Give it power and ground to the respective lugs, and then your audio jack does signal and ground to the same. 

Edited by spectre6000
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8 hours ago, spectre6000 said:

Disclaimer: I'm not an electrical engineer, I only play one on TV.

Looking deeper, I think rodabod may be right. That does look like a higher output amplifier than you'd typically want for a preamp. 3W per channel sounds small to me, but my amplifiers are all quite large by comparison and not pushing little computer speakers or whatever. That's not to say this necessarily won't work, but it might want a larger signal to start than the mic puts out on its own, and could put out more volume than the software knows what to do with. A phono preamp is the exact thing you're most likely looking for, and should play nice with most microphones.

As for the piezo microphone, it looks like it'd play nice on the power side, but the output isn't mentioned (nor are the signal input ranges mentioned on the amplifier).

https://www.sparkfun.com/products/12758

These guys are local to me. Good people, good products. This is your microphone and preamp all matched, soldered, and ready to go. Give it power and ground to the respective lugs, and then your audio jack does signal and ground to the same. 

Hi, I found a similar circuit onlinne and I' gonna order it, I think I'm not gonna know if it's gonna work or not unless I try it and I have been annoying you with my questions.

I'll post a new threat to tell you what happens, I just hope that I don't wire something wrong and blow my laptop that wouldn't be good I'm not sure if that's possible but I'll really carefull anyway.

Thanks alot

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If you were being annoying, we wouldn't keep coming back to help as we can.

It's difficult to blow up your laptop. Move fast and break stuff. Don't give anything more power than it asks for, and the smoke will stay inside. If you screw up, and the smoke DOES get out, just replace whatever little jellybean popped and keep trying.

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I don't suppose you thought about purchasing one of those Chinese timing machines? The 1000 is around $150 to 1900 pool nicer screen for little over 200? There are actually quite nice all self-contained microphone that rotates. Not that the software machines are that bad but you do need to have a proper amplifier circuit and the correct pick up otherwise the results you get can be questionable.

Then if you do a search on the message board we've gone through building circuits for a other suggestions and the Chinese even have now a microphone with built-in preamp that was discussed somewhere if you can't find it doing a search I will see if I can find a link for you.

So I have no problem with the software machines but it's an added level of complication if you're trying to get them to work and learn watch repair at the same time. Plus for those of us helping it can become a problem if your homemade microphone for instance doesn't work that well and we don't get the proper results and yes we've done that dance before two.

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FYI, I looked recently, and I think I was seeing the 1000 at $110US and the 1900 at $150US. No idea what that looks like in Turkey though. They are definitely inexpensive, but the most expensive of the boards mentioned here tops out at around $5. 

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2 hours ago, spectre6000 said:

They are definitely inexpensive, but the most expensive of the boards mentioned here tops out at around $5

that's an interesting comparison I never looked at it that way think of the money I would've saved by the circuit board versus a timing machine or two or three. But you forgot the microphone? Plus the amplifier board has to have the right  input for a ceramic/crystal pickup otherwise is not going to do you much good.

or what about the DIY approach a little solder a breadboard and op amp for two is all explained at the link below

https://www.watchrepairtalk.com/topic/3002-d-i-y-watch-timing-machine/

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Hi  I build the watch o scope setup and as long as you use sheilded cable (screened cable)  the whole set up works ok I have had no problems at all. Piezo disc came from an old alarm buzzer, the amp was a kit from Maplins(now defunct)  At the moment I use the light version to back up my Horotec unit.

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That microphone lacks a preamp, and the OP seems to think that's his ticket. It sounds like he has a microphone, he just doesn't think it's putting out enough of a signal for his software to be happy with.

The microphone came into the conversation to make sure the microphone and the amplifier play nice. He already has one, but seems willing to buy another to ensure efficacy for task.

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looking at the discussion again brings up an amusing problem. For everyone who thinks there timing device is working perfectly how do you know it's working perfectly?

One of the reasons I bring this up is for those of us who answer questions in this group we've had people working on a watch have a problem and problem is based on what they see on their timing app. Or whatever they're using to time their watch and a lot of times the apps the programs the improper microphones etc. do not always give perfect results and can give very misleading things for diagnostics.

31 minutes ago, spectre6000 said:

That microphone lacks a preamp, and the OP seems to think that's his ticket. It sounds like he has a microphone, he just doesn't think it's putting out enough of a signal for his software to be happy with.


ideally if you're doing this right you need a special microphone? Special because you're not trying to listen to the watch even though yes sounds or vibrations ideally you need a pickup for vibrations. At least classically this is how all timing machines work. They're picking up the vibration of the watch.the audio sound. Then classically these are ceramic or crystal and they require special circuitry to match their high impedance to usually something different. For instance computers and probably phones all are looking at were looking for capacitive or as up above it called condensers same thing microphones these have a built-in circuitry. So getting a preamp may not necessarily solve your problem if your microphone isn't really the correct type.

So if you think everything is working perfectly why don't you try timing a ladies watch the smallest mechanical watch you can find and see how well that works. Plus if you had access to another timing machine simultaneously run them together and see what happens that's always amusing.

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