Misspent youth – the Yihua YH-305D

Boy, was I ever young and stupid. It was the summer of 2004 or so, and various Chinese electronics vendors were just starting to flood the US market with some really cool looking toys, and the quality hadn’t faded to zero on them yet either! Mostly….?

At the time I’d just gone through a big mess with most of my workshop having been left out in the rain for several days in my absence, so I didn’t have a power supply. I bought this Yihua YH-305D on eBay and thought it was pretty great for the price, even after it arrived with the instruction manual calling it a “DC POWRE SUPPY” and the plastic nuts on the front panel binding posts don’t actually… work. (I got around this using banana plug leads.)

Years later it finally occurred to me to be suspicious of the fact that the constant current regulation is sloppy as hell, and the cooling fan starts to run if you draw more than one amp off it continuously. At five amps steady draw, the Powre Suppy doesn’t get noticeably warm, but the fan continues to howl forever.

I opened it and realized just how misspent my youth truly was.

wp-1483573643309.jpgThis… beautiful… board greeted me right away. There are places where traces kinda got half etched over there on the side then subsequently, but incompletely, covered with solder to fix it. Ummmmmmmm yeeeeeaaaaah D-

wp-1483573603318.jpgThe underside of the regulator pass transistor assembly. That’s three *supposed* 2N3055 transistors, paralleled. Why would you need three 2N3055’s for five amps?? You can run 15 amps through ONE real 2N3055 if it’s heatsinked properly. Oh wait, I forgot the key word… real. Genuine. Official. Not Pure Unadulterated Chineseium. I couldn’t get a picture of the labels on these “2N3055” transistors that were SO GOOD that they had to put three in parallel to pass 5 amps, but I was able to get a peek at it and they were printed in a gray looking ink with a nonsense logo– it looked like the Marvell Semiconductors logo??!! Either way, this video details what I’m probably actually looking at and why they are… very… very… derated.

The heatsink they are bolted to also explains the fan behavior. It’s nothing more than a flat plate with very little mass and surface area.

wp-1483574274591.jpgThe fan sucks up air from right above it and exhausts it out the back when the thermal switch seen in the background snaps on. I’m not sure how hot it has to get to trigger that, but it sure gets there in no time.

wp-1483573638001.jpgThe main filter capacitor looks underwhelming and I have my doubts it’s actually a Rubycon as its clothing would suggest.

 

This is paired to, uhhh, the death capacitor, as I lovingly call it. If you are using a power supply like this as a limited current source and you lose connection to the load momentarily, and the voltage limit is significantly higher than the voltage the load pulls it down to, any capacitor on the output will be charged up to that level. Once connection is reestablished to the load, it is presented with very high available current at this higher voltage. I detonated some high efficiency white LEDs under test with a power supply like this years ago while trying to develop a boost converter based driver for solar lighting applications and was royally pissed. So, without further ado, the death cap…

wp-1483573631845.jpgand…. the… rubber cement disaster of the century. The entire front of the supply is just…… bespooged with this cement…. Another red cement is found splattered all over the place as well. At left in the above picture is the digital meter board which I am not even going to touch let alone try to calibrate the screwed up zero point on, FORGET THIS

 

wp-1483573620558.jpgThe board is supported only by one small bracket from the rear; if I drop this power supply it will experience the sweet release of death it so sorely longs for.

 

Yeah. I was young and stupid and I bought this.

 

There’s a great thread on EEVBlog’s forum about these, including the wonderful thing that happens when you switch one on and it goes wham, overshoot, boing, boing, boing, and either stops bouncing or… not…

 

Amateur Radio Testing January 8 in Palm Beach

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Picture entirely unrelated

Are you around Palm Beach and want to take the exam to become an amateur radio operator or upgrade to a higher license class? See below.

Still need to study or take a practice exam to see if you’re ready? Check out HamStudy.org.

Bring photo ID and a calculator to the exam session. Since this is a Laurel VEC session, don’t bring the exam fee, as there is none. 😉

Dear Amateur,

This Sunday the Palms West Amateur Radio Club Laurel VEC team will be giving exams for all classes of Amateur Radio licenses.

Come and test with us on Sunday, January 8 at 10:00 AM at Fire Station #28, 1040 Royal Palm Beach Blvd, Royal Palm Beach 1 block south of Okeechobee Blvd.  There is no charge, and you do not have to register.

If you are coming to upgrade, please bring a copy of your license and a photo ID card, like your driver’s license.  There is no charge for testing!

If you know of someone who has been studying to become a ham, bring them along, even if they feel they need to do more studying.

And if you are a VE, please let me know if you can come and help.

73, John, K2CIB
RadioWhiz at gmail dot com

American Dream… I’m so done

I’m so very very DONE and so are your chances of ever getting anywhere on the roads in northwest Miami-Dade in 2020. I had heard nothing but radio silence on this project for over a year, and this is probably why– they were trying hard to apply decorative wallpaper to an elephant in the room to conceal it.

“It is unlikely that all needed interchange improvements will be approved and constructed by 2020, the build out year for ADM,” Lisa Colmenares, a state transportation planner for South Florida, wrote in a Nov. 23 letter to Miami-Dade. “If any of the interchange improvements fail to be approved … by 2020, the base transportation network that is the foundation of [the county’s] traffic analysis will be invalid.”

They don’t even know—–

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Here’s its likeness in cable nightmare form.

Floridawave or something

Please take a moment to admire and ponder this.

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I mean– really, seriously admire and ponder this. There are so many messages here. So many statements it has for you.

You’re welcome.

Measure up: a beautiful vintage meter.

So a meter is a meter is a meter, right?

Bzzzzzzzzzz.

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This monster is nearly eight and a half inches wide.

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Neat scale.

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Spade tipped needle.

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The passive scale illumination: a ground glass band on top allows ambient light to light the dial.

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Connection post. This isn’t exactly a blazing sensitive meter– putting a digital multimeter set to ohms across it yields no visible deflection. (Some meters peg!) Setting the DMM to diode check, which usually applies 5mA or so, gave me about a 61. Please admire that rough carpentry. I love finding things like this!

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Better view of that nicely made wooden base. Unlike the edges of the connection post holes, the outside is immaculate.

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Dwarfing a Gossen Lunasix.

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Hand written serial number.

What was this made for? Judging by the lack of any visible brand name, wood tabletop base, and unusual scale with no units, I’m suspecting it was a classroom/lab piece. You’d calibrate with a known voltage reference and do the math yourself. You know, old school nonsense. 😉

The low sensitivity is curious too. I’ll have to test later and see just what scales out to a 100.

I did open the meter briefly because there was some loose material rattling around that I didn’t want damaging the movement. An old wire wound spool resistor is mounted inside in parallel with the movement, likely for damping. It looked similar to the spools in my Weston but covered in cloth tape instead of wax.

Florida, we need to talk…

Winter is to COLD as Florida is to:
A) DERP
B) HERP DERP
C) DURRRRRRRRR
D) All of the above

floridawinterPlease note: this image is from December 19, 2016. There’s an image floating around on social media from like 2013 that shows the same phenomenon. You can use either one to describe it as both are equally true. Map source: Weather Underground.

Bang!

I’m still baffled by this one. I’m going down 595 eastbound past Davie when there’s suddenly a massive bang… I didn’t see any objects in the road prior to this but something must have hit hard. I pulled over and found the wheel well liner wrapped around the wheel and what’s left of the front bumper unsnapped from its tracks.

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There was once a big black plastic pan here.

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Flapping in the breeze.

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I do hope that dangling wire would have been for the fog lights on a fancier trim model

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The remains of the pan I had to remove because it was dragging and there’s nothing left to attach it to

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There is no real evidence of what may I may have hit in the road, but it sure did a nice job of demolishing all the plastic parts.

Oh well. Likely coming soon: a post in which I detail reassembling the front of a car in 88 degree December weather.

Crap Power Strips

This has significantly bothered me for a while.

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This is one of the most common power strips available now, as it’s the least expensive available out of China. Note what happens if you miss just a little plugging in a two prong plug. If you touched the prong here and any grounded object, hi diddly shockarino, neighbor!

But guess who doesn’t seem to have a problem with this.

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Genuine meaningless hologram.

This strip is available under a number of brand names including General Electric, Westinghouse, Belkin, Sunbeam, whoever the retailer licensed a brand name from that week. You should not buy it.

¡Come Pinga!

Best driver of the year award goes to….. Girl who spent more on her weave and her phone than she did on her car, who slowly drifted out of her lane while poring over something on her phone.

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Fuck this city, I had to go hurry up to go wait in traffic and didn't get time to paint my nails as usual

I didn’t notice this until I felt a very wrong sensation and heard an odd sound and my car started wanting to push left. I looked over and the first thing I saw was my rear view mirror stuck right through her open window next to her face.

I realized I didn’t want to spook her because she’d do something and make it worse… So I gently moved left, getting my mirror out of her oblivious face and gave her some room…. then let loose with the horn.

The phone popped back down and she swerved all the hell over the place before slamming the gas and leaving a cloud of blue gray smoke. Then the phone popped right back up again and she rear ended a dump truck ten seconds later. Of course since she’s already on SR-22 she just ran. So did the dump truck.

But that’s none of my business.

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