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EEVblab / Re: suggestion: solder + flux
« Last post by nanofrog on Today at 04:47:48 PM »
Another vote for Kester 44 (63/37).  :-+

As it's flux is RA, it's good for repairs and NOS components as it can cut through any oxidation. FWIW, CML Supply breaks down liquid fluxes (186, 1544, 951, 959T) as well as Easy Paste 256.
Dodgy Technology / Re: Another Free Energy craft project
« Last post by james_s on Today at 04:41:11 PM »
I have wondered about the heat output from burning fuels although I've never seen any data. I suspect it's relatively small compared to the amount of energy from the sun so it may not have much effect. Burning a candle is not going to warm you up nearly as much as putting on a coat or getting under a blanket.

Methane does get brought up, it's a popular argument from the hard core vegan crowd. The thing that bothers me most about that is all that fuel (methane) just floating uselessly up into the air.
General Chat / Re: What did you build today ? Post your small project!
« Last post by NiHaoMike on Today at 04:39:44 PM »
A crazy contraption to flash a neon light that uses a broken smartphone as an oscillator.
General Chat / Re: Toy find
« Last post by Cyberdragon on Today at 04:39:37 PM »
My in laws have one of those in their sitting room table drawer. I play it every time I visit Scotland.

They were popular in the 70s apparently.
Test Equipment / Re: Kirkby calibration kit alternatives?
« Last post by hendorog on Today at 04:38:43 PM »
This is a bit left field, but bear with me as it could be a simple method to get a better characterised cal kit ...

I have an SDR kits cal kit which is only supplied with electrical delay values. It has no fringing capacitance coefficents.
The open standard in the kit is just a dust cap. It has no effect on the measurement, at least not significant enough to matter.
Therefore the open standard is just the open female SMA adapter which I have on the port of my test set.

Taking a punt here and assuming that the female SMA adapter (which came with the Rosenberger SDR kit) I have is very similar to someone elses.

Therefore, could someone with a nice cal kit (G0HZU?) do me a big favour and sweep an open female SMA, and post the S1P file?

Then I'll take the file, try and run it through the script and see what C0,C1,C2,C3 values come out. Then put them into the VNA and try it out.

The short and load are already covered - there are no L0,L1,L2,L3 fields in the old VNA's for shorts, so I can't input those anyway.
Since I already have the delay for the short, so that is the best I can do for now.

I already have the SDR Kits load, as well as several non-precision 18GHz Inmet loads from eBay, out of which I have selected a few which measure quite close to 50 ohms at DC. The best I can do here is hope that they are still close enough to 50 ohms up to 6 GHz. At least they all compare sensibly with each other and with the SDR Kits load.

Anyone still with me? :)
There are various ways to flash all kinds of lights with a smartphone, but how many of those will work with a broken smartphone?
Thanks for labelling your schematic but since its filter opamps are backwards then I cannot see if they are the Sallen-Key highpass with a high Q for a low frequency boost that I use or if they are Multiple Feedback Bandpass Filters.

I expect a schematic to look something like this:
That circuit of yours is not a smart multiband limiter.  It also doesn't give the realtime whopping 1 through 100x gain at 3 different bands with V-VLF below 5hz protection like my circuit.

Working backwards:
     Take a careful look at the trick I'm performing.  The green led create a very soft knee VS current limiter, with a smoothing 100nf cap (C14), before the LEDs, (looking at the left channel), I have the Subsonic gain 10k pot fed in series with 10uf (C22), which removes the very low frequencies and will rapidly charge and discharge in the event of the volume being up too high through the leds.  But you need to go further back to see that there is a 1Kohm series feed to a 1uf to GND, (R10 & C16), then go back further, there is another 1Kohm series and 10uf to GND (R5 and C20).  What I have done here, is there are across these 3 LPF filters, at 3 bands + the 4th super low cut filter (C22), a different level of current being allowed through to push the green led slightly further and further.  It is something akin to using multiple resistor and diode steps to convert a triangle wave into a sine wave design you see in some function generators, but, with the LPF in my design, even if you force a square wave through, it will still come out rounded like a sine wave.

     Remember, this board is NOT a simple equalizer with a very low frequency volume knob.  You can get that effect just by turning up the VLF channel on you DVD player/Sound system.  What my device does is separate out the VLF, auto volume it up to the max continuously, referencing only to the VLF content and adjusting on 3 different VLF bands, then re-mix that back onto the normal audio without altering the volume of the normal audio.

     It is an impressive effect which freaks out many who have experienced is at my old house.  No added bass, no signal clipping, yet you feel the breeze in the movies, even in stereo content, like when I used to watch Dr. Who, the sound when inside the Tardis would quietly shake/vibrate my entire house, yet the actors voices and actions and background music wasn't affected at all.  This was the effect I was after, not just a simple over-glorified bass knob.

     Think of this soft over volume rounding of the VLF audio function like a vacuum tube amp with is comforting soft response to overdrive, but just for the VLF channel.
Hey that's cool, I have a few of those TIL311 displays around somewhere, always thought they were neat.
EEVblab / Re: suggestion: solder + flux
« Last post by NickAmes on Today at 04:31:38 PM »
Water-soluble flux is an option if you can't use solvents or tolerate no-clean flux residues. Keep in mind, though, that it must be promptly removed, as it's very corrosive. Lead solder isn't terribly dangerous if you wash your hands after handling it.

As far as rosin fluxes go, I like Kester 44. It's active enough to tin corroded surfaces, has an OK smell, and can usually be treated as a no-clean flux (at least for hobby projects).
Beginners / Re: Buying a ESR meter for In Circuit testing...
« Last post by BradC on Today at 04:30:20 PM »
I put a couple of back to back clamp diodes inside my Bob Parker unit just in case. I haven't tested them yet in anger but I'm pretty sure the test leads will die before the diodes. The only issue with that is it means I can't use the meter to do impedance measurements on batteries, but I didn't build it for that anyway.
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