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Test Equipment / Re: New ANENG multimeter
« Last post by Fungus on Today at 07:19:22 PM »
Regarding the fuse, the DT830D I have also specifies "please install..." Fuse, but there isn't even a Fuse holder inside. That said, I guess one could install a fuse with some work if necessary.

The DT830 is/was quite a good meter but the design was massively cloned and people have been removing anything they can just to save $0.0001 in manufacturing. Fuses were one of the first things to go, followed by buzzers, etc.


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Hi guys,
      Just heard the AmpHour episode #354 – A Meeting Of The Davids. What caught my attention was that the BLE module of BM235 communicates with software running on any platform-- Android, IOS, Windows, etc.

Just a matter of professional interest-- how was that implemented? What development environment was used? What libraries? I am a software guy and am now working on a project where multi platform support is required and I would just like to get a perspective on what was used for BM235. In the past I've used GWT for creating browser based applications that run on anything with a browser- hence multi platform, but GWT's future might be uncertain. I would really appreciate some more technical details about multi-platform design tools that were used for BM235 software.

Thanks.
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1. USB can get you very good sound. In fact, some best specced DACs are USB ones, but don't expect to get any good USB DAC for <$200. I would say Apogee Groove is a good choice, and it has built in volume control and a not too bad decent headphone driver (or you can get a very decent USB DAC with very decent headphone driver, say, Sont PHA3, at almost triple the price).

2. If you insist to make your own volume controlled HP amp, then consider PGA2311 or even CS3318 if you can handle such large chip, for volume control part.

3. For actual amp, I'm not a big fan of the TPA6120A2. Messy TSSOP package with thermal pad, huge poser dissipation, and lack of versatility due to higher integration. I would consider LME49610 plus an OPAMP, or further, a discrete diamond buffer plus a decent OPAMP.

4. If you have the design capability, consider HDAM-SA2 topology with LME49720. Refrain from OPA1612, aka OPA2211, these are quite sensitive to input impedance. These are good for IVC or line buffer (from a low impedance source), not for HPA (driven from a relatively high impedance DAC). If your DAC has built in headphone driver, then OPA1612 can be used. If it's unbuffered voltage output, then use LME497xx series instead.
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Microcontrollers & FPGAs / Re: Segger JLink - Worth it for hobby use ?
« Last post by mac.6 on Today at 07:16:36 PM »
Lot of dev boards include debugger that can be flashed as a JLink debugger, most Kinetis parts are like this for example.
It's not an exact EDU version as most are very slow (around 4/8MHz) so advanced debug is limited (like RTT or SystemView usage).
RTT is a fine software, of course you need to provide some support for lock/unlock functions, it is far above uart and doesn't requires swo support. Only their linux support is lacking for the tools.
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Microcontrollers & FPGAs / Re: help! how to make a nsc800 computer?
« Last post by ali6x944 on Today at 07:16:20 PM »
It kind of works now after I changed the transistor, it stops the cpu's operation and still keeps the address and data bus unchanged even if the cpu is resetted
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Beginners / Re: Want to start making my own circuit board where to start
« Last post by sasa on Today at 07:16:18 PM »

Let's keep things in perspective...

Your stomach is full of hydrochloric acid pH 1.5 to 3.5; that's what produces the burning sensation when you vomit. https://en.wikipedia.org/wiki/Gastric_acid
...

First of all, I will not rely on informations from wikipedia. Author is usually unknown as well his credibility regarding the matter. I do not claim it is incorrect, but still, in this case I'm not gastroenterologist and relying on that claims to make any further conclusions is not quite helpful. I doubt it is "full of hydrochloric acid" , as there is many enzymes involving in digest process, which is quite complex process depending on what is actually digests,  quantity, size, etc...  Otherwise, anyone would be able to digest pure metal. But say no more, this is not related issue at all.

Secondly, relativistic approach on this matter is not allowed - no mistake is allowed. The only golden rule is : MAXIMUM SAFETY! Not only for you, but for your family, neighbours and his family... If that would be primary  reason, especially in industry (not just blindly running for profit) I doubt we will have any pollution (biological, chemical, radioactive, name it)...

And the last, we are not infant, stupid and irresponsible kids and that is how we should behaves and point out to other safe(r)  alternatives...

Out of topic, but related to your "prank days" you have mentioned:

I recall when I was 6 years old that I was in hospital and that one kid in the same room  broke body thermometer (old glass and Mercury style) and immediately started to play with Mercury drops in the bed. I have noted that and told him not to do that, not to swallow it nor to put fingers on the face or mouth until I get nurse, as that is poison and he will badly get sick and may die... My parents teched me what is hazardous from early age and even I did not fully understood why, I have alway behaves responsible according that. Even kids do not understood fully concept of death in early age, they know very well what happens when get sick...

Furthermore, some high school teachers are quite frustrated and incompetent persons, not capable enough for even what they do (not mentioned anything else), thus behaves irresponsible just as their infant students in some life dangerous situations. And some university professor are so vanity and proud on his Ph.D, usually combined with a "God complex", that make it ridiculously pathetic and easy to manipulate with, that many fully incompetent persons pass exams and get University degree with no real knowledge at all...
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Great to have a manual with calibration instructions :)

I used an online contact form in the past, but never got an answer.

I've contacted them for manual for the digistant 6425 T a while ago, they where very responsive and help-full.  :-+
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Power supply looks fine. Maybe add some TCS protection or Ferrite beads. Ferrite beads help a lot with the RF interference coming from eg mobile phones.

I'm going to add some ferrite beads between analog and digital GND. may I have to add t also in other points?

I'm also looking at the TPS65131 that offers positive and negative rails up to +-15V from single 5V supply.. but I'm not sure if it can introduce some interference and noise in an audio application (it's rated for audio in the datasheet)

The ferrite bead between GNDs... I'm not sure if that is a good idea. It is one of those things that can make things worse, and you might never know. I prefer keeping AGND and DGND tied together, and provide a continous GND plane. This is definetly better for EMC.

TPS65131: While it lists audio applications, I dont know about it. Look at those nasty graphs at page 21 and 22. I see 50mV+ ripple on the rails. I have bad experience with "power saver" SMPSes with precision circuits. They go into power save mode, and suddenly they make audible noise and pollute everything around them with ripple.
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General Chat / Re: [Solved] MacBook recommendation needed
« Last post by blueskull on Today at 07:06:47 PM »
Although I did knock my 6s in a sink of water and it had absolutely no effect other than make me very nervous.

iPhones are not IP rated due to liability considerations, but they are designed to be waterproof to certain degree.
An opposite example is Xperia, some of their phones are marketed as waterproof, but many die due to water damage.

OT:

I used to be a hardcore Sony fan, until my last Xperia "soft died" (still 100% functional, but irreversible software "upgrade" makes it so slow that it's not practically usable) in 6 months. I'm happy with my new blazing fast OnePlus 5 without built in bloatware. The Sony bloatware is an art on its own. There's not many bloatware APKs, instead, the "Android OS" along takes 2GB of RAM right on boot up. This must be optimized by someone with special, one of a kind, stupidity, especially considering the phone only has 3GB of RAM, albeit being a so called flagship phone in 2016.
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Yes, I am starting to realise that another scope and psu would be handy. I'm thinking I could buy a Rigol DS1074Z and maybe make some PSU. What do you think?

Is it better to make a big 48+ V 1-3 A PSU or a couple of 15 V 1 A PSU to put in series or parallel to get higher voltages or currents?

I know of at least two cases now were people replaced the 22xx preregulator circuit with a 48V switching power supply brick adjusted to 42.5 volts.

I do not suggest designing and building an off-line switching power supply.

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