Do you life activities include diagnosing bad capacitors on circuit boards? Take the time to build an in-circuit capacitor tester and stop needlessly replacing caps that are fine! It takes just seconds to go thru a board and identify all the bad caps!
Most modern scopes have USB connectors so there's the 5V, bye bye regulator.
Most scopes also have a calibration square wave output so bye bye 555, perhaps even bye bye transistor output stage.
That might leave some wires, some connectors and a 220Ω resistor.
@RueNahcMohr Thank you for elaborating. I think I understand the expected waveform with good/bad ESR if we are looking at a _single_ capacitor.
However, if there are two capacitors in parallel and only one is bad, I would expect to see the same waveform irrespective of which capacitor I probed, right? So then I would still have to pull one out of the circuit to know which of the two was bad? Or am I still missing something?
@RueNahcMohr here's my in circuit ESR checker.
https://webshed.org/projects/in-circuit-esr-meter/
Works quite nicely.
An Equivalent Series Resistance Meter Some time ago I was trying to repair a switched mode power supply (SMPS) in my oscilloscope. I’d been quoted £800 for a new PSU, so trying to fix it first was well worth my while. It’s pretty common for electrolytic capacitors to develop faults in an SMPS; specifically they develop an higher than normal internal resistance. So while the capacitor may hold a charge and measure as the correct capacitance, it will not behave correctly in a filter or PSU circuit. The ESR of a large high voltage, high capacity electrolytic capacitor should be fractions of an Ohm, smaller capacitors have ESRs of a few Ohms typically. As the capacitor degrades in use the ESR can easily climb to several hundred times the normal value, while exhibiting no changes to voltage and capacitance ratings Suspecting the capacitors, and not having a way to measure their series resistance, I set out to design and build an ESR meter.
@RueNahcMohr @dtl
Finally got around to doing a thing: https://pears.zenerdio.de
It's by no means final. It's barely functional at this point.
The RSS-crawler as of now is a hot mess. I've stolen a lot of the code from my other search engine project and added a weird set of adapters to make it work with pears. Works as a prototype, but definitely not something I'd hand to somebody else. I'll do a big clean-up soonish and release it.
Also I ran into some bugs with pears (https://github.com/PeARSearch/PeARS-federated/issues/123)... A workaround on my end is in the works, that probably means that I have to nuke my index and start over.
@RueNahcMohr @dtl Depends on what you call simple. As soon as a CMS is involved there's a lot markup mixed in with the text.
Even on my site I have syntax highlighting for source code and mathjax to render latex style formulas. Combine that with the responsive theme I wrote and you get a lot of stuff.
That's one of the reasons why I use to RSS/Atom feeds to figure out if the contents changed.
@dtl Most CMSs/static site generators do that out of the box. Some even bump the timestamp if there are new comments.
The reason why I focus on RSS is that I want my crawler to have minimal resource implications on the sites it visits. You should be able to host your stuff on a raspi and survive being indexed.
Try marginalia search. It’s pretty good.
seems to have a bunch of corp websites in it...
@tom_verbeure @RueNahcMohr It's already on there.
I designed and built this in 2011 so I'm not quite sure of the design choices now. I remember breadboading it and 1 stage wouldn't reliably start.
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