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.
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mediatechnology
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Re: Entropy

Post by mediatechnology »

It's been really hard to get interested in electronics and bench work lately when there's sawdust to be made, grass to be cut and tools to be repaired.
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mediatechnology
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Re: Entropy

Post by mediatechnology »

Upon further reflection JR you could have sim'd taking out that stump and saved yourself a lot of real, hard, dirty work.[/sarc]
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JR.
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Re: Entropy

Post by JR. »

mediatechnology wrote: Sun Sep 16, 2018 7:16 am Upon further reflection JR you could have sim'd taking out that stump and saved yourself a lot of real, hard, dirty work.[/sarc]
Good idea... :lol:

I haven't mowed my rain ditches for two weeks, and not doing them today either... I need a break.

JR
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Re: Entropy

Post by Gold »

mediatechnology wrote: Sat Sep 15, 2018 9:15 pm It's been really hard to get interested in electronics and bench work lately when there's sawdust to be made, grass to be cut and tools to be repaired.
I’m in the opposite place. I feel I have to get better acquainted with my test bench to be able to improve my skills and builds. I feel like I’ve gotten as far as I have through brute force. My tank of brute force is running low. To make things better will require more finesse.

I’ve been working on the bench setup and trying to figure out how to make common tasks easier and better.

Up for today (after the Mets game) is to figure out a 9VDC PSU for my Panduit label makers. They go through 6 AA batteries at a clip and I’m tired of the $10 refills. Not to mention dumping batteries is the trash is the only option at work. I’d rather they didn’t go into landfills.

There is no current spec anywhere in the manual or on the unit. I’ll measure current draw by using a 9V battery. I have a bunch of linear supply boards I’m not using. I have a power transformer with dual 9V secondaries. If the units don’t draw more than 1.5A then it’s easy. If they do I’ll have to read up on a LM338 and see if it’s a drop in sub for an LM317.

I have a desktop 9VDC 3A supply but the connector is the wrong polarity. I don’t know what that PSU is for so I’d rather not clip the connector. I might need it in the future. If making a new PSU looks like too much work I’ll just change the polarity of the PSU I have and call it a day.
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JR.
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Re: Entropy

Post by JR. »

Me and my test bench have an understanding... don't ask, don't tell.... :lol:

back on topic (entropy), while today was supposed to be a day of rest I have some housekeeping to deal with from that last month of intensive yard work.
----
I noticed yesterday one front tire on my big dog mower was soft... I ignored it and cut my yard anyhow. It is a major PIA because the tire valve stem is impossible to reach with my toy compressor. I had to jack up the mower with my car scissor jack, and unbolt the front wheels... now done and both are rocking 40 PSI again. I don't know why they use tubeless tires on mowers (yes I do, they're cheaper).

I've had to fill this front tire 2x this year so likely to get worse.
---
while the compressor was out and plugged in, I topped off my car tires. well 32# is not really topped off but that little compressor was straining and 32# is better than 25#.
===

As long as I was cleaning up old business I swapped out the incandescent light bulb I put in my laundry room last winter when I was worried about pipes freezing. I used a decent sized CFL I had sitting around..(now I can see again). I have a small pile of these CFLs I am too cheap to throw away, because they still work.
======
now for an actual repair, and this is first human assisted entropy, with a glue repair that failed (actual entropy) after a half century. While me putting it outdoors in MS weather did not help the glue job.
DSCF0038.JPG
The brown smutz around the original break is some 50-60 year old glue. This Chinaman statue used to sit in an alcove off the landing of the stairs between the first and second floor of the house I grew up in NJ... My visiting grandmother apparently trying to find the bathroom in the middle of night fell on the stairs and the china man got the worst of the fall... It was glued back together no doubt to make grandma feel better. I ended up with it as a passive-aggressive consolation prize... I visited my younger sister (RIP) before she died and asked her to give me my fathers papers (He was a WE/RCA recording engineer). She ended up with them when my mother died (I have some of his books and technical journals that my mother gave me while she was alive, but these papers were more personal stuff). For some inexplicable reason she declined to give them to me :oops:, instead she gave me that busted up china man statue.... gotta love little sisters, a true PIA to the very end. :lol: (I never got those papers even after she died, I wasn't close enough with her husband to stay in contact and ask for them).
DSCF0039.JPG
Here is China(man) reunified again.... this was not valuable pottery before it was busted... It looks like the head was cast as a separate part and maybe the child too... the face has slots for perhaps adding an optional goatee and/or beard.

We'll see if the 5 minute epoxy outlasts the previous half century glue job? (This was a win-win since I had some old 2 part epoxy sitting around rotting the plastic bag it was in..)

JR
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Re: Entropy

Post by Gold »

JR. wrote: Sun Sep 16, 2018 4:48 pm Me and my test bench have an understanding... don't ask, don't tell.... :lol:
If you know what you are doing you don't need a belt and braces test bench. I however need as much help as I can get.
back on topic (entropy), while today was supposed to be a day of rest I have some housekeeping to deal with from that last month of intensive yard work.
I thought it was on topic. Label maker no longer working the way I want it. Time to fix it. I fixed it.

I tried measuring current draw with a 9V battery but I guess it can't provide enough current even when new. So I grabbed the PSU with the 3.5mm plug with reversed polarity. With alligator clips I reversed the polarity into the label maker. It drew no more than 800ma so my original plan using an LM317 would work. Then it occurred to me to just make a polarity reverse cable as the easiest non invasive solution. Done and done.
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mediatechnology
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Re: Entropy

Post by mediatechnology »

I think JR was trying to steer himself back on topic. Everyone's broken stuff and their repairs are really interesting IMHO.

Paul: What you might do on that 9V adapter is make the cable polarity-reversible with a 2 conductor connector that will mate either one way or 180° opposite. Radio shack used to make adapters that way with pins that plugged into the barrel connector.

You could cut the existing cord a few inches from the output end and install the male/female connectors there. A nylon molex connector or something like that comes to mind.

I was thinking about changing the large number of batteries in the Brother P-Touch due to age but once I remembered how many there were I just checked them for voltage and leakage. It's quite an investment to load one of those things up.
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Re: Entropy

Post by Gold »

mediatechnology wrote: Sun Sep 16, 2018 6:15 pm Paul: What you might do on that 9V adapter is make the cable polarity-reversible with a 2 conductor connector that will mate either one way or 180° opposite. Radio shack used to make adapters that way with pins that plugged into the barrel connector.
I forgot I had female chassis mount 3.5mm connectors. I made a polarity reverse female to male 3.5mm cable. That way I didn't have to clip the existing connector. I used lots of shrink wrap to make sure nothing would short out. Those little 3.5mm connectors are delicate. One wrong flex and they short.

I am a bit dyslexic. I was never diagnosed but I make those binary kind of mistakes all the time. A connector that can be reversed is a recipe for disaster in my case. I try to idiot proof anything like that because I will screw that up.
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Re: Entropy

Post by JR. »

Gold wrote: Sun Sep 16, 2018 6:59 pm
mediatechnology wrote: Sun Sep 16, 2018 6:15 pm Paul: What you might do on that 9V adapter is make the cable polarity-reversible with a 2 conductor connector that will mate either one way or 180° opposite. Radio shack used to make adapters that way with pins that plugged into the barrel connector.
I forgot I had female chassis mount 3.5mm connectors. I made a polarity reverse female to male 3.5mm cable. That way I didn't have to clip the existing connector. I used lots of shrink wrap to make sure nothing would short out. Those little 3.5mm connectors are delicate. One wrong flex and they short.

I am a bit dyslexic. I was never diagnosed but I make those binary kind of mistakes all the time. A connector that can be reversed is a recipe for disaster in my case. I try to idiot proof anything like that because I will screw that up.
Channel that and use it... There is an old design axiom (sometimes conflated with Murphy's Law) that any component or sub assembly that can be installed backwards will be installed backwards with bad result. I think of that when designing sub assemblies to make them harder to assemble wrong.

===

WRT test bench entropy indeed, specialized cables often break from repeated use, so you must constantly be alert for that.

Me and my test bench don't hang out as much as decades past.

JR
Last edited by JR. on Mon Sep 17, 2018 10:27 am, edited 1 time in total.
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Re: Entropy

Post by mediatechnology »

That Radio Shack adapter was indeed complicated.

The male end, coming from the wall-wart, had markings which read "+" and "-" on each side.

The connectors - I think there were 5 or 6 of different sizes - had markings which read "tip" and "outer." (Maybe not outer.)

It took me months of research to figure out how to get positive polarity on the tip. Months I tell you.
I finally had to go to the store to ask how to reverse it. ;)
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