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Repair / Re: Service Manual for Chroma 12061
« Last post by coromonadalix on Yesterday at 11:53:44 pm »some fw for the m3500 use at your own risk
Recent Posts
82
Beginners / Re: Amscope trinocular microscope and Eakins camera issues
« Last post by newtekuser on Yesterday at 11:35:23 pm »Link to what you bought please, and maybe take a photo of your setup.
With a trinocular camera, the image should be near enough what you see using the eyepieces, once adjusted. So probably the spacing or positioning of the camera is off. What adapter are you using? Does it have adjustments on it?
https://www.eevblog.com/forum/reviews/new-trinocular-microscope-what-im-doing-wrong/
https://www.eevblog.com/forum/reviews/eakins-microscope-big-problems/
Attached a pic of my setup and this is the camera I've got: https://www.aliexpress.us/item/3256805573018177.html?spm=a2g0o.order_list.order_list_main.16.38ad1802HXfKnH&gatewayAdapt=glo2usa
I played around with the camera setting but none helped.
83
Test Equipment / Re: NEW Keysight HD3
« Last post by Wolfgang on Yesterday at 11:31:01 pm »Hello,
in the online event from 18 September 2024 about the HD3, at 16:48 it says that the HD3 has a resolution of 2 uV at 2 mV/div. That corresponds to only 13 bits.
Best regards
egonotto
Hmm, maybe the ENOB and actual NOB are different?
... these marketing fuzzies dont get it. Only ENOB bits are useful, all beyond fall victim to noise and nonlinearities.
What I would like to see for the physics and precision measurement guys would be an UXH scope (100MHz, 13-14Bits ENOB)
84
Projects, Designs, and Technical Stuff / Re: Suggestions and guidelines for DIY test fixture for high densidty PCB
« Last post by Smokey on Yesterday at 11:21:09 pm »Another thing to think about, and maybe more important than the actual connections to the boards, is... what mechanical process are you going to use to load the boards into the fixture, hold them down against the probes/pins, and remove them when finished. If you make this system too complex/fragile/involved then you are in for some troubles if you plan on making this for "production".
Here is an example of a simple mechanical fixture. It aligns and clamps the boards with one motion on that lid (as opposed to a bunch of screws, or multiple levers, or other such stuff that seems like a good idea until you actually have to use the thing you designed in your head).
https://www.automatiqsystems.com/versitraq.html
Another example:
https://www.testfixtures.com/pcb-test-fixtures/
As for the actual pogo pins, I would stay away from anything smaller than ones designed for 0.1" pin pitch holes. I've used rows of the those into through holes and that worked ok. They are pretty easy to damage if you aren't careful though.
Note: Sorry, I remembered 2mm pitch but they were actually 0.1" pitch.
Here is an example of a simple mechanical fixture. It aligns and clamps the boards with one motion on that lid (as opposed to a bunch of screws, or multiple levers, or other such stuff that seems like a good idea until you actually have to use the thing you designed in your head).
https://www.automatiqsystems.com/versitraq.html
Another example:
https://www.testfixtures.com/pcb-test-fixtures/
As for the actual pogo pins, I would stay away from anything smaller than ones designed for 0.1" pin pitch holes. I've used rows of the those into through holes and that worked ok. They are pretty easy to damage if you aren't careful though.
Note: Sorry, I remembered 2mm pitch but they were actually 0.1" pitch.
85
Projects, Designs, and Technical Stuff / Re: Edge Detection
« Last post by PCB.Wiz on Yesterday at 11:16:54 pm »...You could cobble something with 555, but those are long time constants, and timing becomes a lottery.
At this time I need to start a timer to wait for T1 seconds (need to be adjustable in range of 0 to 20 sec with potentiometer)
After T1 I Need to switch TTL signal (going to optocoupler) for T2 seconds (need to be adjustable in range of 60 secs to 120 secs with potentiometer)
I would like to achieve this with some gate and probably one or 2 x 555.
If your tutor says do not use MCU, then smarter would be to use CMOS counters like 4060/4521/4541, which allow much faster RC oscillators and more precision
You can select a choice of two pots with a SPDT analog switch, so chosen out = LOW = t1_POT and out = HI = t2_POT
One counter/divider then manages both delay and pulse times.
Zero time is not a real thing, so you need to choose some sensible pot ratio eg 100:1 for T1 gives 0.2s-20s or 20:1 gives 1s-20s
Add a schmitt part like 74HCS74 or 74HCS72 for your choice of _/= or =\_ trigger and you are done. (eg uses a 74HCS72 to halt after pulse =\_ )
86
Beginners / Re: Amscope trinocular microscope and Eakins camera issues
« Last post by thm_w on Yesterday at 11:11:28 pm »Link to what you bought please, and maybe take a photo of your setup.
With a trinocular camera, the image should be near enough what you see using the eyepieces, once adjusted. So probably the spacing or positioning of the camera is off. What adapter are you using? Does it have adjustments on it?
https://www.eevblog.com/forum/reviews/new-trinocular-microscope-what-im-doing-wrong/
https://www.eevblog.com/forum/reviews/eakins-microscope-big-problems/
With a trinocular camera, the image should be near enough what you see using the eyepieces, once adjusted. So probably the spacing or positioning of the camera is off. What adapter are you using? Does it have adjustments on it?
https://www.eevblog.com/forum/reviews/new-trinocular-microscope-what-im-doing-wrong/
https://www.eevblog.com/forum/reviews/eakins-microscope-big-problems/
87
Buy/Sell/Wanted / Re: Free - Old Silicon Chip magazines
« Last post by johnboxall on Yesterday at 11:07:27 pm »Hi,
By any chance, magazine still available? I need the December 1987, frequency counter part2 article.
Thanks
Wow, that takes me back. Are you building it? Where did you get the 101xx ICs from?
88
Test Equipment / Re: Hioki IM3570 LCR & Impedance Analyzer
« Last post by KungFuJosh on Yesterday at 11:07:18 pm »I was curious about how the resistance ranges functioned differently between the IM3570, and the 3532-50 so I popped it open and took a photo. The design of the IM3570 made it so I couldn't answer my question without a lot of effort, so I only took the one photo and closed it back up.
It's clearly a nice design. It looks like the top PCB doesn't need to be unmounted, and that there are separate screws for the top plate to be removed with the PCB still attached. But I didn't have the time or ambition to go further now.
The Xilinx Spartan chip says XC3SD1800A. Some of the others are easier to read, some are not. 😉
Thanks,
Josh
It's clearly a nice design. It looks like the top PCB doesn't need to be unmounted, and that there are separate screws for the top plate to be removed with the PCB still attached. But I didn't have the time or ambition to go further now.
The Xilinx Spartan chip says XC3SD1800A. Some of the others are easier to read, some are not. 😉
Thanks,
Josh
89
Buy/Sell/Wanted / Essentra BRR015B
« Last post by perdrix on Yesterday at 11:06:59 pm »I'm looking to buy four of these 1/2" diameter bumpers/feet. Live in the UK.
Digikey stock them - is anyone in UK placing an order from Digikey in the near future that could add four of these:
https://www.digikey.co.uk/en/products/detail/essentra-components/BRR015B/9343101
to their order and send them on to me? Naturally I'll pay cost (£1.83 inc. VAT) and postage.
Thanks David
Digikey stock them - is anyone in UK placing an order from Digikey in the near future that could add four of these:
https://www.digikey.co.uk/en/products/detail/essentra-components/BRR015B/9343101
to their order and send them on to me? Naturally I'll pay cost (£1.83 inc. VAT) and postage.
Thanks David
90
Repair / Re: 18V/3A HY1503 PSU - weird CC/CV behavior while charging battery cells
« Last post by iMo on Yesterday at 11:03:19 pm »The aprox 2MHz signal at the psu's output is below 40mVpp with active CC, and the CC basically works.
There is a clean signal when CC is set off. Oscillation is visible in entire active CC region.
The original is 120pF in the fb.Tried blocking the inputs, various RC combinations in the feedback (C from 330 to 6n8, R 0/1k/4k7/10k), 22 ohm resistor at the opamp's output, messing with wiring layout, etc. The amplitude at the output of the opamp decreases perhaps by 30% with larger values of caps. The third and fourth opamp in the package is clean, supplies clean. The oscillation is of course visible everywhere with low amplitude as it is boosted by the transistors.
PS: the 1k or 100ohm in the BE of the 2N3055 has no impact on the amplitude.
There is a clean signal when CC is set off. Oscillation is visible in entire active CC region.
The original is 120pF in the fb.Tried blocking the inputs, various RC combinations in the feedback (C from 330 to 6n8, R 0/1k/4k7/10k), 22 ohm resistor at the opamp's output, messing with wiring layout, etc. The amplitude at the output of the opamp decreases perhaps by 30% with larger values of caps. The third and fourth opamp in the package is clean, supplies clean. The oscillation is of course visible everywhere with low amplitude as it is boosted by the transistors.
PS: the 1k or 100ohm in the BE of the 2N3055 has no impact on the amplitude.