Entropy

Relax in southern comfort on the east bank of the Mississippi. You're just around the corner from Beale Street and Sun Records. Watch the ducks, throw back a few and tell us what's on your mind.
Gold
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Re: Entropy

Post by Gold »

Here is the cable. There is clear shrink wrap over the wires.
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mediatechnology
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Re: Entropy

Post by mediatechnology »

I like it!
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Re: Entropy

Post by Gold »

I should be getting my Studio Six Digital iAudio Interface2 back in the next week or so. I bought it about three years ago to have FFT capability on the bench and acoustic measurement capabilities. I played around with it but never integrated into the test setup. I needed to know the AP better so I put it aside.The monitor switching on the Portable One I still find confusing but I've got a better handle on it.

A few months ago I decided to pull it out. I couldn't find the PSU that came with it. In the manual it said the interface needed 12VDC but on the unit it said it needed 9VDC. I figured I'd start with 9VDC and go to 12VDC if it 9VDC didn't work. I powered it up with 9VDC and heard a Pfft. I blew it up. Turns out it wants 5VDC.The silkscreen of the 5 looks like a 9. It has a PSU board and an Audio board. The PSU board needed to be replaced.

I think a BNC patch bay may be in my future. I have some 16" x 4" pieces of FR4 and some chassis mount BNC's. I think I can get something going with that.
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JR.
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Re: Entropy

Post by JR. »

JR. wrote: Sun Aug 05, 2018 10:42 am
emrr wrote: Sat Aug 04, 2018 9:34 pm Wow, 140º is way up there. Reverse flowing bleach sounds on the surface like a good option.
I don't want to jinx it by declaring victory too soon, but last night and again this morning I was able to brush my teeth with water that didn't smell bad. 8-)

I ran the hot water longer than the first time I tried this (set a timer for 10 minutes). Not to mention the pipes were already warmed up from my shower before I did this. 140' is the magic number to kill bacteria, and if I was measuring that crudely with my meat thermometer in the water coming out of my faucet, the pipes and water may have been even hotter where the smell was living. Now I can screw the aerator back on, because it wasn't the problem this time.

I will leave the cold water turned off under the sink for a while just to see if it stays clean smelling. From time to time I can smell my (cold) tap water, the joys of living in a poor small town.

JR
The bathroom sink water smelled clean for more than a month before the off smell slowly returned. From when the smell shows up, it is not in the sink faucet but a little ways upstream in the plumbing.

I just ran the hot water for another 10 minutes... not very green but I may need to do this several times, or for even longer than 10 minutes, before wiping out the biotic critters. Since the cold water is off and these are not coming through the hot water tank, these are from the same old colony that was knocked down but not completely wiped out last time. Perhaps longer run next time if this one doesn't work.

JR

PS: I burned up the last of the wet stump wood yesterday... I ended up adding dead tree limbs from two different neighbors to my burn pile to completely burn my pecan stump.
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JR.
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Re: Entropy

Post by JR. »

Another old soldier repaired. I cracked the old handle trying to pry loose my pecan stump.

Good as new now, I even aligned the grain of the wood properly for strength.
DSCF0045.JPG
JR

PS: Sink water does not stink again (yet?)...
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mediatechnology
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Aging Super Capacitors and Car Batteries

Post by mediatechnology »

One of my repairs this week was replacing the "super capacitors" 0.1F/5.5V in several Radio Shack STA-300 receivers I have scattered throughout the house. I use them with Minumus 7's for computer workstations and in the garage etc.

They're from the 1990s and had begun to forget station settings when powered down for more than a few seconds. It requires removing a couple of dozen screws to get the main board out but the whole repair, including cleaning pots is less than 1/2 hour.

Going back to JR's car battery I found this recent article "Keeping an aging battery charged": https://www.edn.com/design/power-manage ... y-charged-
A little research reveals that automotive lead acid batteries are different than deep cycle or stationary batteries. Automotive batteries are designed to maximize current capacity for cranking and do not respond well to deep discharge or float charging (also known as stage 3 charge cycle). The plate structure of starter batteries maximizes surface area and the electrolyte specific gravity (SG) is higher than in other batteries in order to deliver the high cranking current. Like stationary batteries, automotive batteries allowed to remain in a state of deep discharge experience permanent sulfation, where the small lead sulfate crystals produced during periods of discharge convert to a stable crystalline form and deposit on the negative plates. Float charging automotive batteries, on the other hand, can easily cause over-saturation leading to oxidation of the positive plates also shortening the battery’s life. Charging voltages and charging cycles are therefore quite critical and are different for automotive and deep cycle types; furthermore, charging voltage should be de-rated with ambient temperature at a rate of 3mV per degree C above 25ºC.
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Re: Entropy

Post by Gold »

I've been trying to not buy stuff and see if I can put some of the tools and supplies over the years to use. It feels like I have enough stuff and it's time to get the most out of it rather that buy new stuff. I've been wanting a cold cut chop saw for cutting metal but they are about $450. That's not in the budget at the moment. I have a 14" abrasive cut off wheel that I've been using to cut bar stock and round stock. It works well enough but it's too big to set up on my workbench so I end up crouching on the floor. This isn't ideal. It's hard to get the lighting right to see well and it's physically uncomfortable. This makes it hard to accurately measure mark and cut. I end up rushing because it's uncomfortable and that leads to mistakes. In addition the cutoff wheel makes a decent but not great cut.I usually have to file afterwards.

A few years ago I bought a metal cutting circular saw. I thought I would want to cut aluminum sheet to size for faceplates. It proved too unwieldy for some of the same reasons the cutoff wheel is unwieldy. I ended up ordering pre cut pieces. It was much easier. So the circular saw just sat there unused. Yesterday it hit me that for bar stock I could clamp the saw and the workpiece down in a makeshift jig and do a plunge cut. Fairly easy to set up on the workbench. It worked like a charm. It's by far the cleanest, straightest, quickest cut I've ever done in that material. It was easy to line up the scribe on the workpiece with saw blade using a small machinists square. Clamp and go.


download/file.php?mode=view&id=483&sid= ... bc5f9623b0
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JR.
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Re: Entropy

Post by JR. »

My first generation drum tuner used a heavy aluminum extrusion.

I cut them too length with a Craftsman Miter saw and metal cutting blade.

(yes I wore ear plugs)

JR
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Re: Aging Super Capacitors and Car Batteries

Post by JR. »

mediatechnology wrote: Sat Sep 29, 2018 3:22 pm
Going back to JR's car battery I found this recent article "Keeping an aging battery charged": https://www.edn.com/design/power-manage ... y-charged-
A little research reveals that automotive lead acid batteries are different than deep cycle or stationary batteries. Automotive batteries are designed to maximize current capacity for cranking and do not respond well to deep discharge or float charging (also known as stage 3 charge cycle). The plate structure of starter batteries maximizes surface area and the electrolyte specific gravity (SG) is higher than in other batteries in order to deliver the high cranking current. Like stationary batteries, automotive batteries allowed to remain in a state of deep discharge experience permanent sulfation, where the small lead sulfate crystals produced during periods of discharge convert to a stable crystalline form and deposit on the negative plates. Float charging automotive batteries, on the other hand, can easily cause over-saturation leading to oxidation of the positive plates also shortening the battery’s life. Charging voltages and charging cycles are therefore quite critical and are different for automotive and deep cycle types; furthermore, charging voltage should be de-rated with ambient temperature at a rate of 3mV per degree C above 25ºC.
I had to resist the temptation to reinvent any more wheels... I bought a pretty fancy charger that must be doing some ciphering because it takes several hours to fully charge my already (not discharged) battery every week. I drive about 8 miles each way to food shop, once a week... Over time this was not enough drive time to keep my battery fresh...I noticed slow cranking in cold weather, but battery test just said it needed a charge.

I am optimistic that this could (should) be my last new car battery. :lol: (while car is over 20 YO so past due too).

JR
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Re: Entropy

Post by Gold »

Wood cutting saws generally run in the 10000-15000 RPM range. The cutoff wheel also runs about that speed. The carbide tipped metal cutting blades are supposed to run at 3500-5500 RPM depending on how thick the blade is. That’s why I didn’t put a saw blade in the abrasive cutting wheel. The circular saw runs at 3900 RPM. Carbide hates heat so running it fast dulls the blade faster.
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