Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 1803268 times)

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Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15175 on: August 24, 2018, 07:48:00 am »
In Other News...




My fuses & precision resistors from n2cbu have arrived; Fuses test to spec for resistance as advertised and now the ones I snurched from my Ragu 17B are back where they belong.

It took some jiggery-pokery to get good contact through the baggies, but 100ohm 0.1% resistors read 100.09/100.11ohm, and the 5.315K 0.1% I could get contact with read 5316ohms with the 189. I think that's pretty good. Still awaiting the rest of my parts to make the cheap resistance array, and I'm loathe to take them out of the baggies until I'm ready to build.

mnem
ZZZzzzZZZzzzombie...

I got somethings from him too, most for no real good reason other than the prices were good and I'll keep them in my spares stock.  The adapters and attenuators will go in my RF goodies box, and I want to try the DC-DC converters for driving nixies.



Incoming QA inspected things and approved, too, so it's decent stuff...


-Pat

Well if it passes the inspection, it must be good  ;) What is it with cats and things in plastic bags, my 2 cats are the same, have to inspect anything in a plastic bag and they love to lick them all the time  :-DD
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Offline tautech

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15176 on: August 24, 2018, 08:00:34 am »
The moment I start carrying a new shipment inside our cat is looking for which box to claim as her own.   ::)
Get a new unit out to do my pre-dispatch checks and I'm swatting her off the empty box.

One day she'll get shipped to some unsuspecting customer.  >:D
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Offline Cubdriver

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15177 on: August 24, 2018, 08:13:50 am »
Well if it passes the inspection, it must be good  ;) What is it with cats and things in plastic bags, my 2 cats are the same, have to inspect anything in a plastic bag and they love to lick them all the time  :-DD

 :-DD :-DD :-DD  Lick.   :-DD :-DD :-DD

I wish all the little buggers did was lick!




Piglet and Gilmore seem most inclined to this. :wtf:

And of course they ingest some of it, then barf it up later - normally while I'm asleep, and typically somewhere on the path between the bed and the bathroom - that increases the likelihood that I'll step on it with my bare feet while half asleep in the dark.  I think this amuses them greatly.
 :rant: :rant:

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline Cubdriver

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15178 on: August 24, 2018, 08:14:51 am »
The moment I start carrying a new shipment inside our cat is looking for which box to claim as her own.   ::)
Get a new unit out to do my pre-dispatch checks and I'm swatting her off the empty box.

One day she'll get shipped to some unsuspecting customer.  >:D

Make sure you poke some air holes in the box!

 :P

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15179 on: August 24, 2018, 08:16:16 am »
Reminds me of this which I saw the other day:



Edit: my father's cat was hilarious. I chewed through a mains cable and hit live. There was a thud as it hit the underneath of the table, shot off and ran straight into the glass door on the back of the house. Never chewed anything ever again after that.
« Last Edit: August 24, 2018, 08:17:55 am by bd139 »
 

Offline tautech

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15180 on: August 24, 2018, 08:21:22 am »
Reminds me of this which I saw the other day:



Edit: my father's cat was hilarious. I chewed through a mains cable and hit live. There was a thud as it hit the underneath of the table, shot off and ran straight into the glass door on the back of the house. Never chewed anything ever again after that.
:-DD

Static won't work everywhere and over all seasons, bugger !
Bits of clear sticky tape laid in ambush work pretty well and they won't go anywhere things for a while after they've had it stuck on a few paws.  >:D
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Offline Cubdriver

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15181 on: August 24, 2018, 08:21:34 am »
Reminds me of this which I saw the other day:



Edit: my father's cat was hilarious. I chewed through a mains cable and hit live. There was a thud as it hit the underneath of the table, shot off and ran straight into the glass door on the back of the house. Never chewed anything ever again after that.

Not the mains cable, but that picture!   :-DD :-DD :-DD :-DD :-DD :-DD :-DD :-DD :-DD :-DD :-DD :-+ :-+

(Though the mains cable is kind of funny, too, given that the cat was apparently unhurt and learned that lesson but good...)

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15182 on: August 24, 2018, 08:54:43 am »
The moment I start carrying a new shipment inside our cat is looking for which box to claim as her own.   ::)
Get a new unit out to do my pre-dispatch checks and I'm swatting her off the empty box.

One day she'll get shipped to some unsuspecting customer.  >:D
I'll keep her with my 2 girls if I'm that lucky customer then  :-DD :-DD
Who let Murphy in?
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15183 on: August 24, 2018, 08:58:14 am »
Well if it passes the inspection, it must be good  ;) What is it with cats and things in plastic bags, my 2 cats are the same, have to inspect anything in a plastic bag and they love to lick them all the time  :-DD

 :-DD :-DD :-DD  Lick.   :-DD :-DD :-DD

I wish all the little buggers did was lick!




Piglet and Gilmore seem most inclined to this. :wtf:

And of course they ingest some of it, then barf it up later - normally while I'm asleep, and typically somewhere on the path between the bed and the bathroom - that increases the likelihood that I'll step on it with my bare feet while half asleep in the dark.  I think this amuses them greatly.
 :rant: :rant:

-Pat

I think mine would do the same but they get shut in the kitchen overnight in their own beds otherwise they would either be on my bed or laying on the floor somewhere and likely to get trodden on when going to the bathroom in the night  :popcorn:
Who let Murphy in?
 

Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15184 on: August 24, 2018, 09:30:58 am »
I wish I could have a cat but unfortunately my landlord doesn't allow pets.  :--

Ever notice that cats love to walk directly in front of you and then stop short and you trip over them?  |O
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15185 on: August 24, 2018, 09:53:44 am »
Personally I hate cats and don't want one. They're other people's problems and shall remain that way.

Dirty, needy, murder all the wildlife, toxoplasma gondii, get hair over everything, expensive vet fees, horrible smelling food, twisted violent, unpredictable and generally useless as a service animal as well. We had a cat years ago we got to catch mice and it was useless. It'd just lick them a bit. This resulted in me having to regularly chase a damp mouse around the living room taking pot shots at it with a metal ruler. Had to get rid of it in the end as it went for my daughter. Just few across the room at her and dug claws in. She was only 8 months old then.  :--

No pets rule in this house. Can go to the local urban farm if they want to do that stuff. And wash their hands afterwards!

Edit: plus my father's one used to come and sit on my face when I was asleep. Total wanker that cat.
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15186 on: August 24, 2018, 10:10:39 am »
My cats are just the opposite, hardly ever leave their own garden, don't murder anything other than a few flies, moths, spiders, daddy long legs etc hardly cost anything in vets bills as they are very healthy cats and generally very predictable and certainly aren't dirty, they have been trained to use a their cat litter tray which gets cleaned daily and often. Biggest problem is their fur when they malt but with a decent powerful vacuum cleaner they can hovered up.

To boot they are proven to aid longevity as they lower their pulse rate as they stroke them and generally introduce a calming effect on their owners so its all good.
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15187 on: August 24, 2018, 10:13:09 am »
Oh I forgot about cat shit. Nothing worse than cat shit. Apart from baby shit and that stops after a bit.
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15188 on: August 24, 2018, 10:18:57 am »
Yeah, but cat shit in decent cat litter doesn't smell as clean cats which most are unless they were taken from their mums to early so they missed that part of they education, will turn round and promptly bury they shit in litter which clings onto it to encapsulate and seal the smell in so you don't get to enjoy it. But one you don't have to do with a cat is to endure taking them shopping with you and generally being pests in public  :-DD :-DD
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15189 on: August 24, 2018, 10:20:56 am »
Apart from the curly whirlies our neighbour's cat leaves in my vegetable patch  :--

I rule with an iron fist :)
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15190 on: August 24, 2018, 10:27:01 am »
That's probably because your neighbours don't treat them as a pet and leave them shut out most of the time once they get beyond the kitten stage and become adults. That's the problem we have with neighbours who have cats, they even chuck pet beds and food outside for their cats  :wtf: One of our neighbours also have a small dog and that is hut outside all the time and lives in a small kennel and spends most of daytime whining because its wants to go indoors for some love, company, warmth and food but necessarily in that order  :-DD 
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15191 on: August 24, 2018, 10:32:25 am »
Standard Essex family ;) ... my younger sister is like that.

I went to the local Indian corner shop and bought a massive bag of chilli powder and doused the entire veg patch with it on a very dry day last time. That stops them shitting on it. Moment they start digging...
 

Online med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15192 on: August 24, 2018, 10:38:28 am »
Personally I hate cats and don't want one. They're other people's problems and shall remain that way.

Dirty, needy, murder all the wildlife, toxoplasma gondii, get hair over everything, expensive vet fees, horrible smelling food, twisted violent, unpredictable and generally useless as a service animal as well. We had a cat years ago we got to catch mice and it was useless. It'd just lick them a bit. This resulted in me having to regularly chase a damp mouse around the living room taking pot shots at it with a metal ruler. Had to get rid of it in the end as it went for my daughter. Just few across the room at her and dug claws in. She was only 8 months old then.  :--

No pets rule in this house. Can go to the local urban farm if they want to do that stuff. And wash their hands afterwards!

Edit: plus my father's one used to come and sit on my face when I was asleep. Total wanker that cat.

Tell us how you really feel  :-DD
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15193 on: August 24, 2018, 10:49:06 am »
Hahaha :)

Ok back on TEA now, a rare subject. I spent some time over the last few weeks analysing different methods of determining unknown and very low inductance. All the off the shelf instruments have terribly parasitics. I have found the best and most accurate method finally. Requires a simple 74LS04 oscillator, a 2.2K resistor, a known capacitor (I used a 100pF silver mica 1%) and a scope. Set the 74LS04 up to generate a square wave at around 1KHz and use a spare inverter to buffer it. Connect a 4.7k resistor in series and the parallel the cap and the unknown inductor and connect that across the cold side of the resistor and ground. That has the effect of hitting the circuit like a hammer on a bell. Pop the scope across it with a 10X probe then you just use the scope to measure the ringing frequency and stuff it in f=1/2*pi*sqrt(LC) and solve for L either by hand or lazy way with calc solver. F and C are known. Now this all depends on how good your probe is. Probe capacitance is around 1.2pF if you have 12pF on the front of the scope and the parallel resistance just ruins the Q slightly rather than knocks it off. I can get down to about 50nH with that accurately with a couple of test inductors!  :-+

But you can do better!

So going to build a Pease active probe from troubleshooting analogue circuits. This has a parasitic capacitance of around 0.29pF. Probably slightly less in circuit as well. Fun times  :-+

Edit: also found out that cheapish turned pin IC sockets have around 0.5pF between the pins on them based on differential measurement. If you cut the plastic off, it becomes negligible so solder them on and then snip the plastic off.

Edit 2: Pease probe:

« Last Edit: August 24, 2018, 11:01:36 am by bd139 »
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15194 on: August 24, 2018, 11:21:47 am »
Strikes me that might be as accurate as many of the LCR meters currently on offer with varience of the probes etc.
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15195 on: August 24, 2018, 11:27:24 am »
I reckon I can get down to about 3% at 100nH->1uH. My objective was 5% so I can actually measure HF and VHF toroids.

Under 20uH the Atlas LC45 is shite (10-20% at under 2uH) and that's pretty much the standard in cheap LCRs that aren't made in China.
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15196 on: August 24, 2018, 12:13:50 pm »
New 465 arrived. Good condition. Actually doesn't look and feel like it has been used much. Not even any grime under the legends. Probes are in very good condition. HT is dead as is usual on these. Probably the usual cap and fuse again. Will find out shortly.

If it works I got me a unicorn!
 

Offline Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15197 on: August 24, 2018, 12:27:22 pm »
New 465 arrived. Good condition. Actually doesn't look and feel like it has been used much. Not even any grime under the legends. Probes are in very good condition. HT is dead as is usual on these. Probably the usual cap and fuse again. Will find out shortly.

If it works I got me a unicorn!
Rare as rocking horse shit then [emoji106]
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15198 on: August 24, 2018, 12:38:05 pm »
Cracked it open. HT fuse blown as expected. Will check rails before I put a new one in. It is entirely unmeddled with inside. Totally pristine.
 

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15199 on: August 24, 2018, 12:39:29 pm »
Coincidentally, I got a variac today. It was more expensive than I felt like paying, especially since it was "untested." However, it's a rather rare HP ET-5874. This was only the second one I've seen in the past few years. The last one sold a couple years ago for more than double, so I bit. I couldn't find any docs on it, but an old photo if the interior of one looked like it has either an isolation transformer in line with the variac or the 230V output is just a fixed voltage.

Sweet!  I've never seen one of those!  Great score!

Thanks. I'll let you know if it works. It looked like the original cal stickers were still in place on the enclosure's screws, so I'm hopeful. If all else fails, I've got some analog meters, a variac without an enclosure, and a toroidal transformer around here to rebuild and enhance the thing.

Nice find, that's another different HP one.

Here are some pictures of two others (not mine  :( ), a smaller one and a monster size one (looks to be at least a two person lift).

David
 


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