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Beginners / Re: The old "Replace blue LEDs with red LEDs" 7 segment question (74HC595)
« Last post by trondl on Today at 01:38:55 pm »One 595 per LED segment module (seven in total), and an additional one for the dBFS LEDs.
Recent Posts
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Mechanical & Automation Engineering / Re: Paint Bubbles On Snowblower
« Last post by bostonman on Today at 01:38:52 pm »Bad prep and contamination was my fear.
A few weeks ago I was at the Ariens supplier store where I purchased it and asked whether other customers have complained about the paint. They claim that this was a first they've heard of it, said it's too old to still be under any warranty (which I assumed), and offered to sell touch up spray paint.
The only thing I did differently in the garage (where the snowblower is stored) this past summer was sand wood, not PT, just natural wood. I thought maybe the saw dust did something, but doubt it since it's just wood. My toolbox and car didn't see any sort of issues, but figured I'd mention the wood since it's the only thing I've done different since owning it.
A few weeks ago I was at the Ariens supplier store where I purchased it and asked whether other customers have complained about the paint. They claim that this was a first they've heard of it, said it's too old to still be under any warranty (which I assumed), and offered to sell touch up spray paint.
The only thing I did differently in the garage (where the snowblower is stored) this past summer was sand wood, not PT, just natural wood. I thought maybe the saw dust did something, but doubt it since it's just wood. My toolbox and car didn't see any sort of issues, but figured I'd mention the wood since it's the only thing I've done different since owning it.
3
Beginners / Re: Jutter calculation ?
« Last post by adeuring on Today at 01:38:51 pm »Im playing with DSS FY-6900
and as many complain about jitter signal output , I'm trying to actually characterize it in numbers.
so gen source is 10Mhz OCXO now .. and I can run output up to 60M ; that frequency on pictures is actually 10.000 000.1
my guess I need to pick some most horrendous frequency but I don't know what is that ; like completely uneven , random one ?
I'm writing this based mostly on knowledge about the FY6600 I gathered from reading relevant threads of this forum about the FY6600. AIUI, the FY6900 has only minor modifications, so I assume that the following applies to the FY6900 too.
The FY6600 has an FPGA that is "clocked" from an external 10MHz crystal oscillator. The FPGA has an internal PLL (or has it two PLLs? – I would have to look at the schematics of the FY6600, find the FPGA type and then look into its datasheet, but I'm too lazy to do that now...) The PLL generates a 250MHz clock signal. This clock signal is used to "update" the DACs that generate the output signal.
This "DAC update frequency" is never changed and this means that the FY6600 can only generate "exact" signals with periods that are an integral multiple of 1/250e6 seconds, or 4 ns.
You tried a 10MHz signal, or a period of 100ns. so you have exactly 25 "DAC updates" for one period. Hence you won't see the jitter about which some people complained.
The "neighboring exact periods" are 24 and 26 "DAC updates" per period, or periods of 24*4ns -> 96ns and 26*4ns -> 104ns, i.e. the frequencies 10.416666...MHz and 9.651538...MHz, respectively. (Note that these frequencies cannot be exactly represented as decimal numbers, so it is impossible to set the generator output to these frequencies – or is it possible to set signal periods instead of signal frequencies with the FY6600/FY6900?)
So, if you set the output frequency for example to 10.2MHz, you will get an output signal where the period alternates between 24 and 25 "DAC updates" (96ns and 100ns) per period, so that the period, when averaged over a longer time, equals 1/10.2 µs. Similarly, when you set the output frequency to 9.8MHz, the output signal will have periods that alternate between 100ns and 104ns,
This should be easily visible on your DSO as two lines separated by 4ns when you look at the signal one period before and after the trigger time.
When you choose frequencies that are closer to 10MHz but not exactly 10MHz, the lines on the DSO screen showing the periods 96ns or 104ns should become darker.
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General Technical Chat / H5N1 bird flu and how we're risking another global pandemic
« Last post by NiHaoMike on Today at 01:38:45 pm »https://www.reddit.com/r/H5N1_AvianFlu/comments/1cfdykj/opinion_this_may_be_our_last_chance_to_halt_bird/
Quote
Spillovers from animals to humans are common, yet pandemics are rare because they require a chain of unlucky events to happen one after the other. But pandemics are a numbers game, and a widespread animal outbreak like this raises the risks. When dangerous novel pathogens emerge among humans, there is only a small window of time in which to stop them before they spiral out of control. Neither our animal farming practices nor our public health tools seem up to the task.It's inevitable that factory farming is going to cause another pandemic. If not H5N1, it will be something else later. It adds to the many other health problems related to factory farming as justification to phase it out and replace it with sustainable farming.
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Test Equipment / Re: Siglent Bench DMMs SDM3065X, SDM3055 and SDM3045X
« Last post by rolfdegen on Today at 01:37:51 pm »Hallo friens of electronics
Today I got my new Siglent SDM3055. It works very well and fits well with my Siglent SPD3303x-E power supply. To check the SDM3055 I purchased an AD584-M voltage reference. The reference chip is an AD584 KH. This has an accuracy of 15 ppm/°C and 0.005%V. In the packaging was a current calibration document from March 2024
I let the SDM3055 and AD584 warm up for 1/2 hour and then took voltage measurements.
Certificate of Calibration
I compared the SDM3055 to my UNI-T UT181A with 60,000 counts. These are the results:
SDM3055 (Filter off)
2.5V ==> 2.4995V
5.0V ==> 5.0014V
7.5V ==> 7.4987V
10.0V ==> 10.0001V
UNI-T UT181A
2.5V ==> 2.5001V
5.0V ==> 5.0025V
7.5V ==> 7.500V
10.0V ==> 10.000V
What is Filter ON/OFF function ?
My Evaluation:
Positive
Small case
Large colored display
Negative
Loud case fan (I will convert it after the warranty period)
Today I got my new Siglent SDM3055. It works very well and fits well with my Siglent SPD3303x-E power supply. To check the SDM3055 I purchased an AD584-M voltage reference. The reference chip is an AD584 KH. This has an accuracy of 15 ppm/°C and 0.005%V. In the packaging was a current calibration document from March 2024
I let the SDM3055 and AD584 warm up for 1/2 hour and then took voltage measurements. Certificate of Calibration
I compared the SDM3055 to my UNI-T UT181A with 60,000 counts. These are the results:
SDM3055 (Filter off)
2.5V ==> 2.4995V
5.0V ==> 5.0014V
7.5V ==> 7.4987V
10.0V ==> 10.0001V
UNI-T UT181A
2.5V ==> 2.5001V
5.0V ==> 5.0025V
7.5V ==> 7.500V
10.0V ==> 10.000V
What is Filter ON/OFF function ?
My Evaluation:
Positive
Small case
Large colored display
Negative
Loud case fan (I will convert it after the warranty period)
6
Manufacturing & Assembly / Re: Brief review of the Zhengbang ZB2520HL reflow oven (T-962A alternative)
« Last post by MR on Today at 01:32:33 pm »
I'm not sure why you post these negative comments all the time. If you really think the cost to build, market, and support these is so small, then you should be able to make a very profitable business selling your own "perfect" design...
Most owners of these ovens seem to agree they do a fine job, much better than other cheap ovens like the Puhui range. And not everyone has the time or tools to construct a DIY reflow oven. I've built one using a Reflow Master controller, but the toaster oven I used is crap and I didn't want to waste more time on perfecting it. I just use it for low temperature part drying/baking now.
do some research it's not hard to build a small reflow oven, get one from your local home appliance store. Our local ones offer IR and resistive heating modules inside.
I used 2 IR and 2 resistive lab reflow ovens, the ones with resistive modules always outperformed the IR heaters. IR nor resistive modules are expensive, you can easily source them yourself.
Depending on the parts on your PCB you might get away with an IR reflow oven but for sure they will kill and or degrade more components than the ones with resistive modules.
Try it yourself with mixed pcbs ICs, inductors with plastic head (they're excellent to verify the health of the PCB/components).
We have some PCBs which are almost impossible to reflow reliably with those cheap IR module ovens, especially with non shielded ones. While they are absolutely no problem with ovens with resistive heating modules..
To sum up:
if you want a harder life .. go for cheap chinese IR, surely you'll get some result.
if you want it easier .. pick an oven with resistive modules
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Mechanical & Automation Engineering / Re: Paint Bubbles On Snowblower
« Last post by coromonadalix on Today at 01:31:47 pm »bad prep, contaminated surfaces ...
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Projects, Designs, and Technical Stuff / Re: Help with DIY guitar pedal
« Last post by moffy on Today at 01:29:39 pm »If I had that given to me, I would desolder everything and start again, if that was at all possible.
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Buy/Sell/Wanted / WTB (UK/EU)- Toroidal coil winder & bobbin coil winder
« Last post by NOTsinceAnipper on Today at 01:29:12 pm »Hi - Looking for a toroidal coil winder and a bobbin winder - not worried about how old it is or hand / motor driven either fine.
regards
Tim
regards
Tim
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Mechanical & Automation Engineering / Re: Paint Bubbles On Snowblower
« Last post by BrokenYugo on Today at 01:26:07 pm »I'd guess bad prep, rust under the paint type issues.