Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Beat me to it!

Sometimes you can get a bucket of slicia-gel packets from a footwear shop for free.  A packet in each shoe box adds up quickly...

Tip:  you can bake these packets in the oven to recharge (dry) them, to be used again or after a humid period.  Just not too hot to burn the paper packet.

I'll do you one better. Silica gel is sold as "crystal kitty litter". You can buy kilos of the stuff for around USD15 at your local supermarket. Making up little packets is easy enough with any kind of textile and a stapler. I have attached an example that I just found on a popular online shopping site.

EDIT:

It's even unscented.

I was going for free in my solution!  (yes, I do have Scottish blood in my ancestry)

Even though we have too many cats at home, I never realized that stuff was made from silica gel.  Then again, it is more expensive than clay kitty litter.

Hmmmm, could this crystal kitty litter work in an air dryer?  I am referring to drying the air in a compressed air system (nothing to do with laundry).  The air dryer pellets are about three times more expensive than the kitty litter...

The key to passive dessication of air is slow velocity, high dwell time. Preferably both upstream and downstream of the pump.

mnem
 

[mnementh]

And while we're bashing our respective wire connection methods, I'd like to put forward this little gem, showing the quality and reliabilty of screw terminals:

Oh, come on... just from looking at that snapshot it is very obvious that moisture/corrosion was the cause of the failure. Now you're just agitatin'. 

Also, even after working with them for years, I have yet to meet a HVAC tech who knew his ass from a hole in the ground when it came to actual electrical work. You have no idea how many open circuit/shorted/transposed start/run caps I had to fix which were just plain wired wrong by someone else when I worked for the 'zoo as a punk kid.

Maybe that's just my bad experience, but 

mnem
 

[mnementh]

An adult 70kg male at rest puts out about 100W of heat, and a world class athlete at extremis (say Bradley Wiggins doing the UCI hour) can put out physical work at 500W for an hour at around 18-22% efficiency so producing ~2kW waste heat while doing so. 25,000 BTU (a unit any sane person has to look up to convert to something comprehensible) is 7.3 kWh <- notice the 'h'.

Obvious illustration:    https://youtu.be/S4O5voOCqAQ

Pah, sprinters? Only good for a few seconds at 1kW, perhaps a minute at a reduced power level. Basically by the time they need to get oxygen into those oversized muscles, they're done. It's interesting to compare those legs to someone who can output sustained power for a long time. 

For real sustained power output you need a Wiggo:      Here smashing the UCI hour.

I don't remember the exact figures but basically he had to put 500W continuously into the pedals for a whole hour. For anyone who that doesn't sound impressive to, go down to the gym, find a fixed exercise cycle with an accurate power meter and try to produce 200W continuously for 5 minutes. I believe that Wiggins UCI hour attempt is the only spectator sport that I have watched beginning to end in the last 10 years.

Edit: To add some figures - that toaster stunt produced 0.023 kWh, Wiggins successful UCI hour attempt 0.5 kWh.

So... do you imagine perhaps he was chosen for this particular demonstration specifically because he would fail or at best barely make it in as dramatic a manner as possible...? I mean, they're already stinking up the joint with that whole "for one slice of toast" line of BS...

mnem
 

[mansaxel]

Now you're just agitatin'. 

Yes! Un-agitated dragons just sleep. Yankety-chainety!

Also, even after working with them for years, I have yet to meet a HVAC tech who knew his ass from a hole in the ground when it came to actual electrical work.

Given that this one had sense enough to get a sparky on the job instead of bodging it himself, you might have seen him now.

[beanflying]

And making a random appearance in Oz this evening  eBay auction: #203546717816

[mnementh]

      https://www.amazon.ca/gp/product/B08CRHGLCN/?th=1

mmmmokay... so these are some switches I bought off Amazon when I first started rebuilding my lightsaber, which are still showing as AWOL.  They weren't the kind I wanted, but they were so crazy cheap; like 2/$6 delivered and they helped me make a order minimum, so I got a couple to throw in the drawer.

These particular ones are SPDT Momentary rated 24V (for the LED), but turn-on voltage is still right around 3V, and this is the illumination level at 5V/~1.5mA drive. More than acceptable for a workbench panel, and as the LED is completely isolated, it can be driven directly off a processor pin. The action is very firm with a strong detent and click at aboot 2mm travel.

Given the complete absence of electrical ratings in the listing, I decided to pop one open in the name of science... it appears to have decent-sized contacts, but given the total lack of Common-pin shunt strap in the design and open contact structure with short travel and no arc-control, I'd say def only good for low-voltage control switching at an amp or two max. Less on the NC contact, as it doesn't meet very squarely. Still worth having at the price; sadly, they must've been clearing out a disco product as that particular one is NLA.

They look like clones of Bulgin MPI001 vandal resistant switches, which are available with and without a current limiter resistor on the LED.    ~£27 from RS.

Here is a link to the data sheet, which may be helpful if they are exact clones   --> https://docs.rs-online.com/3936/0900766b8152bfc3.pdf
I used a real one on my +/- 30V linear supply.

Hmmm... looking at those diagrams, I don't see any which are constructed the same as these, so not a safe assumption. I was referring to the 2nd pic above in my dissection of the switch, which I thought I had included in the original post.

As this particular variant is SPDT momentary-contact, most folks are gonna use them for low-current control circuits anyways... but would still nice to know if you could use it for some real amount of current without it welding itself closed or going poofies...

mnem
 

[mnementh]

that's why they invented motorbikes.

Yep and no pushbike could support some of the riders     

*sigh* Yes, there is a reason I built a fatBike for my fat ass...   

mnem
But I do ride almost every day with my son now, so  ...

[mnementh]

   Holy crap what a pain in the arse it was to get this bracket assembly out.

But there are the vertical output transistors now accessible in their strange heatsink. And I compared part numbers with the replacements and they match.  Going to take a break for a while then reassemble. Then smoke test. 

mnem
 

[BU508A]

An adult 70kg male at rest puts out about 100W of heat, and a world class athlete at extremis (say Bradley Wiggins doing the UCI hour) can put out physical work at 500W for an hour at around 18-22% efficiency so producing ~2kW waste heat while doing so. 25,000 BTU (a unit any sane person has to look up to convert to something comprehensible) is 7.3 kWh <- notice the 'h'.

Obvious illustration:    https://youtu.be/S4O5voOCqAQ

Pah, sprinters? Only good for a few seconds at 1kW, perhaps a minute at a reduced power level. Basically by the time they need to get oxygen into those oversized muscles, they're done. It's interesting to compare those legs to someone who can output sustained power for a long time. 

For real sustained power output you need a Wiggo:      Here smashing the UCI hour.

I don't remember the exact figures but basically he had to put 500W continuously into the pedals for a whole hour. For anyone who that doesn't sound impressive to, go down to the gym, find a fixed exercise cycle with an accurate power meter and try to produce 200W continuously for 5 minutes. I believe that Wiggins UCI hour attempt is the only spectator sport that I have watched beginning to end in the last 10 years.

Edit: To add some figures - that toaster stunt produced 0.023 kWh, Wiggins successful UCI hour attempt 0.5 kWh.

So... do you imagine perhaps he was chosen for this particular demonstration specifically because he would fail or at best barely make it in as dramatic a manner as possible...? I mean, they're already stinking up the joint with that whole "for one slice of toast" line of BS...

mnem
 

The guy with the huge thighs is Robert Förstemann.
German Wikipedia is saying: "Besondere Aufmerksamkeit erregen seine Oberschenkel, die den Umfang von 73 Zentimetern haben. Nach eigenen Angaben besitzt er eine angeborene Fehlfunktion des Proteins Myostatin, welches normalerweise das Muskelwachstum hemmen würde."

DeepL translation: His thighs, which have the circumference of 73 centimetres, attract particular attention. According to his own information, he has a congenital malfunction of the protein myostatin, which would normally inhibit muscle growth.

[Andrew_Debbie]

As this particular variant is SPDT momentary-contact, most folks are gonna use them for low-current control circuits anyways... but would still nice to know if you could use it for some real amount of current without it welding itself closed or going poofies...

mnem
 

Not the same at all other than appearance.   

The Bulgin switches are rated  50mA max at 24V. 

More here --> https://docs.rs-online.com/188d/0900766b813eceea.pdf

[mnementh]

Now you're just agitatin'. 

Yes! Un-agitated dragons just sleep. Yankety-chainety!

mnem
you have no how hard it is...

[Andrew_Debbie]

Dana 5100 DMM update:

Budget 'scope arrived. I'm back to troubleshooting.   The 5100AF manual is very good but it is for a 5100AF. There are small differences.  For example the 5100 clock is 1MHz and the 5100AF clock is 2MHz.

Everything was looking OK until I checked the Null Detector output.  Flatline.

My guesses are either C2, which is a tantalum  or the 1V reference.  I'm not going to guess. The high voltage buffer is on the same card as the digitiser.  Anything is possible. 


For those following along, I've attached the schematic.    The 5100 uses a classic dual-slope converter.   The unknown voltage charges capacitor C2  for a known time period, which is  50mS in the 5100AF     Then the capacitor is discharged by the reference voltage (in reverse polarity)  -  Which should trigger the null detect unless it times out.   

Either the reference is faulty or something is wrong on this board. 

[Saskia]

Hubby in EMT vehicle, they suspect another heart attack. I fucking hate this.

[tonyalbus]

Hubby in EMT vehicle, they suspect another heart attack. I fucking hate this.

Damn... Good luck to you both.. and good recovery.

[Andrew_Debbie]

Hubby in EMT vehicle, they suspect another heart attack. I fucking hate this.

     So sorry to hear this.

[Andrew_Debbie]

Dana 5100 fun fact.   Digital ground is at -5V.   Vcc is 0V.     The power supply uses a 7905.

[ch_scr]

Hubby in EMT vehicle, they suspect another heart attack. I fucking hate this.

Oh FFS what deity did you piss off? Remind me to make regular offerings to him/her/it  :/
Wish you get to catch a break soon & speedy recovery for your hubby.

[bd139]

Oh man that sucks  . Hope all works out ok.

[Cerebus]

Oh bloody hell! Sounds like the last thing you need at the moment. Fingers crossed for a swift recovery.

I think you need to chain hubby up somewhere where he can't get into any more trouble. Perhaps handcuff him to a cardiologist? (Welding the handcuffs shut - hubby sounds like the type who would have the good sense to keep a handcuff key handy.)

[Cerebus]

In other news. I finally found something to round that RS order out to 'free shipping' - 3x100 1206 LEDs. Kind of blew well past the £1.70 I needed to spend to get over the 'free shipping' line. 

[bd139]

In other news. I finally found something to round that RS order out to 'free shipping' - 3x100 1206 LEDs. Kind of blew well past the £1.70 I needed to spend to get over the 'free shipping' line. 

Ah yes that reminds me. I received all the bits for the Solartron today from RS and the bin resistors 

Also have some lacing cord coming to do a proper job on the TOPS1

[tggzzz]

Dana 5100 fun fact.   Digital ground is at -5V.   Vcc is 0V.     The power supply uses a 7905.

I've seen "worse". ISTR the Solartron 7075 has them at -16 and -21V, or similar. The actual voltages are set by the requirements of an FET gate.

[tggzzz]

Also have some lacing cord coming to do a proper job on the TOPS1

I was once taught how to do that on a graduate induction course. Never used that "skill", since ribbon cable existed even then.

[Specmaster]

Hubby in EMT vehicle, they suspect another heart attack. I fucking hate this.

Oh no, we are all thinking of the pair of you, this is the very last thing you need right now, sending you both the best of wishes possible, keep thinking positive thoughts Saskia.

[Cerebus]

Also have some lacing cord coming to do a proper job on the TOPS1

I was once taught how to do that on a graduate induction course. Never used that "skill", since ribbon cable existed even then.

The biggest utility of lacing cables is the robustness it imparts to things used in adverse circumstances - fighter aircraft, warships, and anywhere there are musicians or actors. Ribbon cable for everything is the electronics equivalent of a 'carpenter' who uses nails, preferably from a brad gun, for everything.