Test Equipment Anonymous (TEA) group therapy thread

[Cymaphore]

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...

My experience with storing cat litter in a "wet" basement (high relative air humidity): Problematic, because the cat litter is catching humidity from the air and getting hard. Sounds like the effect you desire.

[AVGresponding]

A quick test of a few 2N2222s and MCP 2N2907s with my cheap Chinese component tester revealed correctly identified as NPN/PNP, EBC pinout (as most Chinese versions of these use), expected hFe of ~350/250, and they didn't just explode when I used them to switch a 1157 bulb at 12V/current limited to 300mA.

The chinese transistor packs are usually pretty good. Never found any bad ones. Worth looking up the datasheets for the other parts. The S8050's are fairly decently specced. I built a small RF PA out of them a few years back when I was pissing around with parallel transistor arrangements and managed to get 4W out of 6 of them at 7MHz which is damn near impossible out of anything else that cheap. Even a couple of BD139's you get from ST won't kick that out any more.

I'm quite sure our bd139 can emit over 4W with sufficient stimulus ! 

"The human body generates more bioelectricity than a 120-volt battery and over 25,000 BTUs of body heat," ...

Grrr. That's one of those sets of factoids that gets passed around that's so far off the mark that it's not funny.

[Bijou rant of facts follows.]

Nerve action potential is a brief pulse at around 125 mV peak to peak at some crazy high impedance as the source of the current is a wave of sodium<->potassium ion exchange across the cell wall of the axon. People probing individual nerves in laboratory settings use electrometers to make their measurements possible, that kind of impedance.

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'.

Just the usual Hollywood bullshit.

Also completely ignores conversion losses. You'd generate more electricity by burning whatever you were feeding the humans on, in a furnace heating water to power a typical steam turbine.

[ch_scr]

Oh good, this has been listed on the local ebay classifieds as parts or repair for local pickup 
I was strong yesterday but contacted the seller just now, let's just hope someone else was faster, I don't need more stuff in the repair pile...
But the diff-amp looks cute and saskia might be interested in the scope once she has settled again 
Also the Ph-meter looks like it is nixie-based 
Update on the frequency mixer thingy: quick test shows it somewhat works, obvious flaw is the input stages get as hot as a 2$ pistol when no input signal is present 
In fact, power draw halves from 0.3A to 0.15A when giving it input 
Running that part of the logic from 5.5V seems obviously a bad choice now but thats what adjustable regulators are for 
Edit: Added a picture of the VFD-Nixie module supposedly inside the Ph-meter. Is it ok to make it a clock if it isn't a "real" nixie? 

[Robert763]

(partially already answered by Robert763)

Or as we Brits and Mericans call it a star delta connection

nope, star delta does not use the taps. see below.

and the circuit shown is only for the power, the control circuitry has been omitted.

I did not claim otherwise, but the Kloeckner Moeller Schaltungsbuch listed so many variants of the control circuit that I left it out in the hope that Mansaxel would ask if he needed more.

No a star delta does not use those physical tabs in the motor terminal box, it makes those connections within the starter unit itself by switching the contactors as I described. A 2 speed AC motor does essentially use a modified version of a star delta starter. This can be either contactors or a special manual multipole switch with 1-0-2 configuration so that you have to go through OFF to change speeds otherwise a short circuit would result directly across the 3 phase supply to the motor when switching speeds. The switch or contactors does the reconfiguration of the motor windings, same as the star delta does. The only difference between a 2 speed motor and a normal single speed motor is that in a 2 speed winding, that winding is split into 2 windings per phase and the normal motor has 1 winding per phase.

All standard 3 phase motors can be wired using the links in the motor terminal box, connect them one way, and you have a delta connected motor with a high inrush starting current, connect the links the other way, you get a star connection with a far lower inrush and far lower torque available.

While that is true, it does not change the fact that the dual-speed motor and circuit (Dahlander) changes the effective number of poles and thus the speed. Star-Delta does not change the speed of the motor.
I think that the confusion is because the Dahlander circuit shown includes a Star-Delta like component. It's actually Delta to Double Star.  Depending on motor and application Star-Double Star is also used.

[bd139]

Got a Hermes Heisenpackage. It is simultaneously waiting for collection and at my local depot. At no point can the state of it be actually be determined until it shows up. Which will probably be munted 

[mansaxel]

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:

[Cerebus]

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:

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.

[bd139]

Yeah nothing but respect for that. Sustained output is the hardest. Walking up bloody hills is enough for me 

[tautech]

Yeah nothing but respect for that. Sustained output is the hardest. Walking up bloody hills is enough for me 

Says he that can barely do 4W ! 

[bd139]

Yeah nothing but respect for that. Sustained output is the hardest. Walking up bloody hills is enough for me 

Says he that can barely do 4W ! 

 

I can run a 5k in 18 mins. Not sure how many watts that is.

[beanflying]

The TT mob are just nuts. I am happy if I average over 100W for a 2-3 hour solo ride (average is about 24-26km/hr) while the TDF runs 40-50km/hr. No aspirations here to better myself 

[Saskia]

that's why they invented motorbikes.

[Andrew_Debbie]

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.

[Cerebus]

You may remember that a while back I said that I'd got some of these:



to get in some practice with soldering teeny-tiny DFN/QFN packages.

So today I've taken the next step and I'm getting some boards made. Thought I might as well produce something that would have some practical utility as well as just being a soldering test piece so I've come up with this:



The chip, if you will recall, is the ubiquitous '595 serial->parallel convertor so I've made a little board with 8 LEDs driven by it that can be cascaded. Lets me actually functional test the soldered boards and I often find myself wanting some little status LEDs on microcontroller projects so they'll likely get some future practical use.

I've ordered two sets of boards and a stencil. One set with an ENIG finish, which is what one would reasonably specify when using itty-bitty parts that have tight co-planarity requirements. I've also ordered a set with HASL finish just to see if you can use these kind of parts while still cheaping out. We shall see.

[tggzzz]

Have you been to the power station and its associated slate museum which is located next to the bottom lake and the power station is actually buried in the mountain that the slate was quarried from?

Interesting.  Here in the GWN, we have two lifts which work on the same principle.  Only difference is that the cargo is water, and maybe a few boats.

Those look like two different principles.

The slate quarry lift going down is heavier than the empty lift going up, so gravity "fuels" the lift. The two canal caissons have exactly the same weight whether or not they are loaded. An engine is used to overcome friction losses.

UK examples of canal lifts, old (Anderton, also on the Trent river ) and new (Falkirk):



There are several examples of water-powered lifts, e.g. Lynton and Lynmouth (850ft long, 500ft high) and 3(!) at Bournemouth

[Cerebus]

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

I don't think they are. I got a few sample Chinese ones a goodly while back and while of quite good quality they don't have the heft and polish of the Bulgin ones (which I too have used in the past).

[tonyalbus]

Reorganizing a bit.. found this one... it says HP.
But when i opened it, it seems sort of normal... is this a lower quality series from HP... it just so normal?
any experiances here.. is it any good?

[beanflying]

that's why they invented motorbikes.

Yep and no pushbike could support some of the riders 

[BU508A]

Heads up for the Germans in Lower Saxony:

Are you bored as bd139 and need some repair projects?
Well, there is a pile of R&S and other broken TE available.
Price: 0 Euro, pick-up only. (NAWTS)

https://www.ebay-kleinanzeigen.de/s-anzeige/messgeraete-von-racal-airmec-sowie-rohde-und-schwarz/1837300847-168-19327

[bd139]

Reorganizing a bit.. found this one... it says HP.
But when i opened it, it seems sort of normal... is this a lower quality series from HP... it just so normal?
any experiances here.. is it any good?

They are the continuation of the old HP analogue metered power supplies. They are based on the old Harrison design still to this day but with some more modern parts and safety considerations. They are also almost exactly the same as the higher end digital supplies with the VFDs. The higher end supplies just have programmable DACs to control the I and V parameters and ADCs which are read by the MCU for feedback. That allows them to be GPIB programmed. These ones have analogue or fixed I and V parameters and an LED driver ADC for monitoring instead.

Ergo they are still really good and rated for full load 24/7. And quite frankly fucking expensive new.

I’ve got a (new!) E3630A arriving today from this series 

[Cerebus]

And all that series are passively cooled, so good for things you want sitting around running 24/7 without driving you mad with fan noise. Also electrically quiet too, all the ones I've had have had better noise and ripple than they are specified for.

[med6753]

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. 

   

[tonyalbus]

Reorganizing a bit.. found this one... it says HP.
But when i opened it, it seems sort of normal... is this a lower quality series from HP... it just so normal?
any experiances here.. is it any good?

They are the continuation of the old HP analogue metered power supplies. They are based on the old Harrison design still to this day but with some more modern parts and safety considerations. They are also almost exactly the same as the higher end digital supplies with the VFDs. The higher end supplies just have programmable DACs to control the I and V parameters and ADCs which are read by the MCU for feedback. That allows them to be GPIB programmed. These ones have analogue or fixed I and V parameters and an LED driver ADC for monitoring instead.

Ergo they are still really good and rated for full load 24/7. And quite frankly fucking expensive new.

I’ve got a (new!) E3630A arriving today from this series 

Thank you!...(i bought it in a very busy time in my live and forgot about it.. i checked the XLS .. i payed around 100,- )  i feel a lot better now, knowing it is good.
E3630A, thats the triple output one ?   .. Cool! 

[bd139]

Yep triple output. 100 is about right for a second hand one. They are around 600-700 EUR/GBP new and still sold today.

As Cerebus mentions, they are very quiet and use passive cooling.

Have attached what I’m expecting. Thanks to AVGresponding for pointing it out  .

It has a RIFA in it so replace that ASAP!

[mnementh]

Got a Hermes Heisenpackage. It is simultaneously waiting for collection and at my local depot. At no point can the state of it be actually be determined until it shows up. Which will probably be munted 

Which, if Murphy has anything to do with it, really means it is already winging its way back to sender, but just hasn't been scanned yet.

mnem
Life's a beach; have a ball. Fukkit... have two... and make that highballs...