Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 14556929 times)

Jambalaya and 28 Guests are viewing this topic.

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120150 on: May 19, 2022, 03:15:51 pm »
Will probably get the children "hp" 35s calcs when they need something for school. Just to fuck with teacher brains.

Unlikely to work: they'll probably specify the calculator. That will be to get the correct answer to 1+2*3 (q.v.)

They'll be more likely to specify lack of programs / insist that programs be cleared before tests. [hp] (actual [hp] calcs, not the Chinesium builds like the current 35s) were always grudgingly accepted back in the day.


This is the one they specify for my son's middle school curriculum. Non-programmable, non-graphing, 2 lines with fraction support. Probably will also get him through another year or two of High School as well before he needs to look at things like my TI-83/TI-86.

mnem
"recalculating... recalculating... recalculating" *WHUMMMMP!* "refuckyoulating... refuckyoulating..."  :o
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 
The following users thanked this post: bd139

Offline bd139

  • Super Contributor
  • ***
  • Posts: 23018
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120151 on: May 19, 2022, 03:24:11 pm »
Plenty of calculator for school. My eldest has a Casio FX-991EX and a Casio FX-CG50 at hand. The 991EX is allowed in exams and has a solver built in  :-//
 
The following users thanked this post: mnementh, Specmaster

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120152 on: May 19, 2022, 03:25:56 pm »
But what would I do with such a thing, in the lab ?  Use case example please ?!  ;D
Whenever you take a picture and post it here you put it in the frame. Casually yet prominently.


mnem
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 
The following users thanked this post: bd139

Offline bd139

  • Super Contributor
  • ***
  • Posts: 23018
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120153 on: May 19, 2022, 03:30:35 pm »
Anybody's looking for a nice coffee table ?  :-DD

https://www.ebay.com/itm/224991657657



Was half expecting to see a light bulb on top of it  :-DD
Just plonk a normal table lamp on it, you can choose your own to suit your taste.

What is it's intended use? Checking receive limits and noise floor of RF receivers?  :-//

Measuring carrier to noise ratio (CNR). This is tied to the phase noise of the carrier. So really it's a fancy phase discriminator and downconverter and IF system.

If you wanted noise floor, you'd terminate the input of the radio system and measure the "noise power" if I remember correctly at the output with an RMS responding AC voltmeter. That'll give you the noise floor. Then you an do an MDS measurement (minimum discernible signal) with a carrier injected. So MDS is defined as 3dB above the noise floor so you stuff a signal at say -150dBm on the input and then step it up until there's a 3dB output gain. That's for simple downconverters to audio. Other digital systems are more complicated and I have no idea how you do that and what I said there might be wrong as well :-DD
 
The following users thanked this post: med6753

Offline Vince

  • Super Contributor
  • ***
  • Posts: 4168
  • Country: fr
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120154 on: May 19, 2022, 03:41:03 pm »
Fridge Timer Update


OK so I grabbed my drawer of relays and started looking at them more closely, then "of course" I realized that I forgot to take into account uh.... something important maybe.... like .... COIL VOLTAGE !!!

How many of your relays have a 5V coil ? No, not many I bet.... mine are mostly 12V and 24V... have one 9V and one 6V but with a 5V supply I am not taking chances, so no.

So... I need to up the supply voltage of my circuit to 12V. Not a problem for the CMOS 4060, but my TTL NOR gate is out !  :palm:

Only CMOS chip I have with logic gates in it is a 4011, x4 NAN gates.  Now I could use all 4 of them and wire them up to make me a NOR gate, sure but... boy that sounds so wrong ! So much wiring to do when time comes to do the proto board as well ! No... just no. So I decided to give this circuit a good clean and get rid of the logic chip CMOS or TTL, altogether ! Out with freaking chips... I replaced it with a hand made NOR gate with discrete logic, a couple diodes and a pull-up resistor ! Look at that below... so much more compact, so much cleaner, less wires, so elegant and simple, I just love it ! .. and as you can see on the scope, it works just as well as the digital logic chip !  8)
I used a couple 1N4148. Pull up is 47K. High enough to contain the current draw to sane levels, and low enough to provide enough drive for the base of the transistor that will energize the relay coil  8)

OK so now I am running on 12V I have plenty of relays to choose from.. so let's pick a transistor and wire that up  8)



« Last Edit: May 19, 2022, 03:44:38 pm by Vince »
 
The following users thanked this post: mnementh, factory, cyclin_al, syau

Offline tggzzz

  • Super Contributor
  • ***
  • Posts: 19281
  • Country: gb
  • Numbers, not adjectives
    • Having fun doing more, with less
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120155 on: May 19, 2022, 03:49:12 pm »

Wow that HP 95LX MS-DOS computer looks cool  8) :-+

The 95LX and later 100LX were truly amazing little machine in well built HP quality.
And they were ahead of its time.

Yes, as were the Omnibook 600 and 800. They arguably invented the netbook PC concept in 1996; the Asus EEE (or whatever it was called) came along a few years later.

Usable Win3.1 machines where two batteries were all you needed to run Transport Tycoon all the way from Heathrow to San Francisco.

The unique and innovative pop-out mouse-on-a-stick was remarkable, since (if you were right handed) you could it in mid air, e.g. when the computer was on your lap.



Clit tits and fondlepads were never as good - and still aren't.
« Last Edit: May 19, 2022, 03:58:26 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 
The following users thanked this post: bd139

Offline tggzzz

  • Super Contributor
  • ***
  • Posts: 19281
  • Country: gb
  • Numbers, not adjectives
    • Having fun doing more, with less
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120156 on: May 19, 2022, 03:51:14 pm »


If you throw that HP 32s in evilbay at an insane price, somebody in this planet will pull the trigger.
The real question is, do you want to?  >:D

The prices aren't high enough yet (£80), and too few people realise what the gold "logo" signifies.
« Last Edit: May 19, 2022, 04:01:55 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline bd139

  • Super Contributor
  • ***
  • Posts: 23018
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120157 on: May 19, 2022, 03:55:29 pm »
Insult time!



And here we go let's be realistic.



And offer declined  :-DD

Hope they get the point!
 

Offline Cerebus

  • Super Contributor
  • ***
  • Posts: 10576
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120158 on: May 19, 2022, 04:06:34 pm »
Anybody's looking for a nice coffee table ?  :-DD

https://www.ebay.com/itm/224991657657



Was half expecting to see a light bulb on top of it  :-DD

That's only on the Teasmade version.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
The following users thanked this post: mnementh, Specmaster, bd139

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120159 on: May 19, 2022, 04:10:25 pm »
Here's the solution with 4060+4001: make the 4060 to count to the desired time interval(1h, that's around 4.5Hz oscillator frequency). Connect 4001(1(A),2(B)) to 4060(2(Q13),3(Q14)), and all the other 4001 inputs(C,D,E,F,G,H) to the ground; add power-on reset to the 4060(RC; 10kΩ+10nF).
On the start-up: pin3(J) of the 4001 stays up for 15 minutes, and down for 45 minutes; after that the cycle repeats itself.
Enjoy!
P.S: this timing is doable with the CMOS(7555) 555 >:D :-DD :-DD :-DD
Edit: I've made a schematic, since an image worth a thousand words.
Thanks Zoli !  :-+

Will try that right now.. as it's the most compact design discussed so far, so the easiest / quickest to wire up on a proto board once proven on the breadboard.
I still like your first solution though, with two 4060 and some logic to reset one while the other is counting, as it would allow for a variable duty cycle, which is the aim, rather than a fixed DC / temperature.

Don't know f I have a 4001 though, but sure enough I will have the TTL equivalent, which is much more convenient for prototyping as you don't need to ground all the unused inputs, so less wiring/mess on the proto board, faster build.

OK so let's go do that now !  8)

I better hurry up because old man just messaged me saying he shipped the Thermostat, paying extra for shipping so that maybe I might receive it on Saturday.  So I need to get my timer in service before its purpose in life vanishes !  :-DD

Oh, 7555 / CMOS can do it out of the box ?! Well I just checked, my local electronics shop down town, does carry them in stock ! Bloody expensive though, at 2.5 Euros a piece (65 cents for a regular 555). No, the aim is to cobble something together for free with whatever I have here in the lab.

Maybe... just maybe... it's time to make a serious try at scrounging up some form of thermistor or thermocouple...? :-//

...It's just that there are thermistors and thermocouples everywhere in our lives; it wouldn't surprise me if you have a old PCB, maybe one from a power supply (PC power supplies almost always do) or even a SMPS wall-wart that has one in it.

Oh... another thing. If you have a dead rechargeable battery pack from a laptop, phone, camera, tablet or power tool lying around... odds are it has a thermistor you can repurpose for this experiment as well.

Cheers!

mnem
*6 Degrees of Draconification*
« Last Edit: May 19, 2022, 04:13:01 pm by mnementh »
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 

Offline RolandK

  • Regular Contributor
  • *
  • Posts: 102
  • Country: de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120160 on: May 19, 2022, 04:13:56 pm »
Borrow the one from your meter or microwave oven or meat thermometer.

mnem
 :popcorn:

What "meter" ? No not going to dismantle my poor u-wave oven !!  :horse:
No meat thermometer here either.

I want to design this thing, the time pressure / emergency makes it even more fun...
So... you don't have a proper bench thermometer, or even a "K" thermocouple as used on almost every DMM since the dawn of time...?

What. The. Actual. Fuck.  :wtf:

Seriously, this is an egregious shortcoming we shall have to pick on you for... at least the next 5 minutes.  :-DD

If you go dismantle that cheap digital thermometer you have on the wall right now we'll forgive you... for now.  >:D

mnem
pssst... on most microwaves that have a thermometer, it plugs in. Easy-peasy to borrow. ;)

A whole new world of Kelvin-nuttery awaits! There is nothing to beat the satisfaction of making up an ice point in a 1 litre vacuum flask (using shredded ice from de-ionized water, naturally, for best accuracy), immersing the lab reference PRT probe, and having it read a stable 0.00˚C for hours. My second-best PRT probe read -0.02˚C. A random K-type thermocouple probe read +1.2˚C, which is about average for a K-type. T-types are rather better, usually about ±0.5˚C, but not guaranteed.

Thermistors are generally quite stable, but the response curves vary quite widely and are often mismatched with the curve assumed by the meter. With individual calibration they can give excellent results, within ±0.1˚C.

What, you don't have an HP Quartz thermometer?   :popcorn:
Sadly, no. Do you have one on offer? ;)

  • We are here on TEA. The who has won't give it away before he dies. >:D
  • He looks for a 2nd to repair or because he bought one of 3rd. ::) :palm:
  • After your death the muggles - your children - who offer it on epay dont see the probes and throw them away  :wtf:and you can rotate in your grave. :rant:
  • If you want to get rid of a HP quartz thermometer or probe or pod, please PM me, don't tell anybody else. ;D
Why do old shaffner filters blow? - because there are rifas inside.
Why do rifas blow? Only time shows if the best new thing is really best. Here it is not.
 
The following users thanked this post: BU508A, med6753, capt bullshot, bd139, Kosmic, cyclin_al, syau

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 14483
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120161 on: May 19, 2022, 04:19:32 pm »
Insult time!



And here we go let's be realistic.



And offer declined  :-DD

Hope they get the point!
Ok Ok, thats the last time I send you a bleeding offer  :-DD :-DD >:D
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 
The following users thanked this post: mnementh, bd139

Offline Zoli

  • Frequent Contributor
  • **
  • Posts: 491
  • Country: ca
  • Grumpy old men
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120162 on: May 19, 2022, 04:25:05 pm »
...
Maybe... just maybe... it's time to make a serious try at scrounging up some form of thermistor or thermocouple...? :-//
...
I will send him a few 0.1oC thermistor with the next extra manual... >:D :-DD :-DD :-DD
 
The following users thanked this post: mnementh

Offline RolandK

  • Regular Contributor
  • *
  • Posts: 102
  • Country: de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120163 on: May 19, 2022, 04:25:19 pm »
More pictures...
Why do old shaffner filters blow? - because there are rifas inside.
Why do rifas blow? Only time shows if the best new thing is really best. Here it is not.
 
The following users thanked this post: Robert763, BU508A, med6753, mnementh, capt bullshot, bd139, ch_scr, Kosmic, cyclin_al, syau

Offline Vince

  • Super Contributor
  • ***
  • Posts: 4168
  • Country: fr
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120164 on: May 19, 2022, 04:37:28 pm »
Fridge Timer Update


OK so picked a relay, plenty to choose from with a 12V coil.  Picked a big ass one to be sure it doesn't catch fire, and also because it's got a transparent case. I don't trust relays... I want to see inside to see condition of the contacts and if they operate properly. Also it's just cool to see the contacts  8)

Measured coil resistance, 220R. Under 12V supply minus teh transistor saturation voltage, about 50+ mA.

Picked a 2N2222A transistor, 800mA so plenty enough. hFE 75 so a single mA in the base should be enough. Of course I doubled that hence the 47K as the pull-up in the diode NOR gate, which doubles as the base resistor for the transistor.

I added a diode in series with the base of the transistors to make sure it's not on the vege of conducting when the diodes of the NOR gate are pulled low. That would ruin my day.

I like my transistors so I added a free-wheeling diode across the relay coil. Found a 2A 600V one, should do it  ;D

Then added  a green LED across the coil to provide feedback, tell me when the fridge compressor is running.

Then I fired all that up and... worked first time !!!  :D

Look at that !!!

So now I need solder it permanently on a proper proto board, and I need to make a 12V power supply for it. Well I could just use a spare car battery I have here in the living room just a meter away from the fridge. That would the easiest and fastest way to go about it I guess !  :-DD
However would be cool to power it from the mains instead... would be neater, more practical than having an external power supply...

I will see what I can find laying around. Worse case.. a cheap consumer grade supply, as I have seen so many times.... just a Zener diode with a beefy 3W or so 100K+ series resistor and call it a day !
I had that in an Espresso coffee machine.... and that was powering directly a couple CMOS chips... and it was working just fine !  :o
I do have the relay drawing 60mA for 25% of the time though... so at least I would need a big reservoir cap to store that burst of current.

Stay tuned !  8)

 
The following users thanked this post: Specmaster, ch_scr, cyclin_al, syau, BILLPOD

Offline McBryce

  • Super Contributor
  • ***
  • Posts: 2681
  • Country: de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120165 on: May 19, 2022, 05:03:23 pm »
Wow that HP 95LX MS-DOS computer looks cool  8) :-+

It is. It even has Lotus 123 in ROM, invoked via the blue 123 key.

The manual is ~4 times the volume of the computer, and much heavier!

The later 100LX was slightly improved. There was even the OmniGo 700lx where you could ram a Nokia 2110 mobile phone up its backside. I wonder why that didn't catch on? (Hint: Nokia did it right)


Wow, that thing's tiny. Mobile phones have come a long way. However, my Fuba Porty sports a 9pin Sub-D rs232 port for true compatibility, just don't try carrying it very far...

McBryce.

30 Years making cars more difficult to repair.
 
The following users thanked this post: Vince, Neomys Sapiens

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120166 on: May 19, 2022, 05:15:14 pm »
Bien sûr, la fiche technique que vous avez postée ici est en français... juste pour me torturer, non... ? ;)

Your French is excellent, zero mistake. Very few French people could write this sentence properly these days...  :--

No I didn't mean to torture you, it's just that I don't chose what I find on Google, I get what I get !  ;D
But the previous / wrong doc was in English, lucky you !  ;D
LOL... PURE Google Translate abuse.

I've found that if I translate from English to another language, then translate back to English... if I get back the same as I put in, it usually means those who speak that language will get my correct meaning. If it doesn't, I change the English until I get something that does survive the double-conversion effect.

For example... I started out with "Of course, the datasheet you posted here is in French... just to fuck with my head, right...?" which came out totally wrong both in verb tense and meaning... then changed to "...just to mess with my head, right...?" and it came out even worse, so then I completely reworded to "Of course, the datasheet you posted here is in French... just to torture me, right...?" ;)

mnem
"Parlez-vous français?"
"Juste assez pour me faire gifler."
;)
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 

Offline Vince

  • Super Contributor
  • ***
  • Posts: 4168
  • Country: fr
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120167 on: May 19, 2022, 05:20:59 pm »
Fridge Timer Update

OK the power supply is sorted !

My eye caught something interesting.. a small pile of old electornic junk that a friend gave me recently. He studied electronics like me 30 years ago but like me ended up in another field. In the pile Ispotted guess what... what appears to be a little project he built at school decades ago : a power supply of course !  ;D

Mains in, and a choice of various output voltages : 3 / 6 / 9 / 12 / 15V. there is even an LED to indicate what voltage is selected, how thoughtful.

12V... sounds good for my purposes eh ?!  ;D

Quick clean, quick peak iside out of curiosity and to make sure nothing was going to blow in my face...
Small transformer, discrete diode bridge recitifer, and a LM317 adjustable regulator. The rotary switch switches various resistors to set the 317 output voltage.

I see a fuse on the secondary of the transformer, wrapped in alu foi MacGyver style, because well that's what you do eh !  >:D
Checked the primary to make sure there were no short.. none. So I fired it up.... works just fine.

OK so I have my 12Vdc PSU, cool !

Resurrecting my friends 30 year old school project and giving it a useful purpose... that counts for something to me, so I will go for that solution...

So now I need to solder the components / circuit on a proto board, and find a... a... power socket ! I hope I can find one somewhere !  :-\
No, I ma NOT going to destroy my Dim Bulb Tester merely to get a socket !  :horse:

It's almost 19H30. If I hurry, maybe I can put that timer in service before I go to bed....no time to be wasted....



 
The following users thanked this post: bd139, cyclin_al, syau, Zoli

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 14483
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120168 on: May 19, 2022, 05:23:19 pm »
Currently doing battle with my fecking ink jet printer which prints in colour, only if you want black :rant: :rant: :rant:
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 
The following users thanked this post: Vince

Offline ch_scr

  • Frequent Contributor
  • **
  • Posts: 809
  • Country: de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120169 on: May 19, 2022, 05:24:36 pm »
My tiny computer arrived earlier this week and for something the size of a pc power supply, it's pretty good. Surprisingly heavy (1.5kg) as well. Also I've already had to design & print a fan shroud, to make it draw fresh air exclusively  ::)
 
The following users thanked this post: mnementh, bd139

Offline bd139

  • Super Contributor
  • ***
  • Posts: 23018
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120170 on: May 19, 2022, 05:26:33 pm »
Currently doing battle with my fecking ink jet printer which prints in colour, only if you want black :rant: :rant: :rant:

HP? Send it back to hell  >:D

Sitting on a train here on way to random meetup.com curry night. Wish my intestines luck  :-DD
 
The following users thanked this post: mnementh, Specmaster, ch_scr, cyclin_al

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120171 on: May 19, 2022, 05:30:19 pm »
Fridge Timer Update


OK so picked a relay, plenty to choose from with a 12V coil.  Picked a big ass one to be sure it doesn't catch fire, and also because it's got a transparent case. I don't trust relays... I want to see inside to see condition of the contacts and if they operate properly. Also it's just cool to see the contacts  8)

Measured coil resistance, 220R. Under 12V supply minus teh transistor saturation voltage, about 50+ mA.

Picked a 2N2222A transistor, 800mA so plenty enough. hFE 75 so a single mA in the base should be enough. Of course I doubled that hence the 47K as the pull-up in the diode NOR gate, which doubles as the base resistor for the transistor.

I added a diode in series with the base of the transistors to make sure it's not on the vege of conducting when the diodes of the NOR gate are pulled low. That would ruin my day.

I like my transistors so I added a free-wheeling diode across the relay coil. Found a 2A 600V one, should do it  ;D

Then added  a green LED across the coil to provide feedback, tell me when the fridge compressor is running.

Then I fired all that up and... worked first time !!!  :D

Look at that !!!

So now I need solder it permanently on a proper proto board, and I need to make a 12V power supply for it. Well I could just use a spare car battery I have here in the living room just a meter away from the fridge. That would the easiest and fastest way to go about it I guess !  :-DD
However would be cool to power it from the mains instead... would be neater, more practical than having an external power supply...

I will see what I can find laying around. Worse case.. a cheap consumer grade supply, as I have seen so many times.... just a Zener diode with a beefy 3W or so 100K+ series resistor and call it a day !
I had that in an Espresso coffee machine.... and that was powering directly a couple CMOS chips... and it was working just fine !  :o
I do have the relay drawing 60mA for 25% of the time though... so at least I would need a big reservoir cap to store that burst of current.

Stay tuned !  8)

Sorry, I wasn't paying attention back when you were working on the timer... just to be sure: You need to make sure the compressor has off time of at least 5-10 minutes to allow the refrigerant to bleed back, or the compressor will be trying to start against a partial head of freon under pressure.

Should not run much more than 5-10 minutes at a time, unless trying to bring temp down a lot of degrees. Oh, and make sure you include the circulating fan in your plans, so it runs as well; if you don't, the fridge side will not get any cold air and the evap will frost shut in the freezer side.

mnem
 :-/O
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120172 on: May 19, 2022, 05:37:39 pm »
Fridge Timer Update
...So now I need to solder the components / circuit on a proto board, and find a... a... power socket ! I hope I can find one somewhere !  :-\
No, I ma NOT going to destroy my Dim Bulb Tester merely to get a socket !  :horse:

It's almost 19H30. If I hurry, maybe I can put that timer in service before I go to bed....no time to be wasted....


I'd be a lot more worried aboot getting a actual fuse in that power supply so it doesn't burn down the house you have half-built. ;)

I mean... seriously. This is a temp application; why even bother with a PCB? Maybe to make the relay & AC power wiring safer and easier, sure... but the timer, etc I'd leave on the solderless breadboard. :-//

mnem
Unless you have a pet frog about the house you don't want to admit to... ;)
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 

Offline factory

  • Super Contributor
  • ***
  • Posts: 2844
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120173 on: May 19, 2022, 05:37:44 pm »
Insult time!



And here we go let's be realistic.



And offer declined  :-DD

Hope they get the point!

Cheaper to buy one from the US, than that local seller, approx £90 including shipping & fees.  :palm:
https://www.ebay.com/itm/384896886993



David
« Last Edit: May 19, 2022, 05:43:04 pm by factory »
 
The following users thanked this post: bd139

Offline capt bullshot

  • Super Contributor
  • ***
  • Posts: 3033
  • Country: de
    • Mostly useless stuff, but nice to have: wunderkis.de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #120174 on: May 19, 2022, 05:39:53 pm »
Fridge Timer Update


OK so picked a relay, plenty to choose from with a 12V coil.  Picked a big ass one to be sure it doesn't catch fire, and also because it's got a transparent case. I don't trust relays... I want to see inside to see condition of the contacts and if they operate properly. Also it's just cool to see the contacts  8)

...

Then added  a green LED across the coil to provide feedback, tell me when the fridge compressor is running.

Then I fired all that up and... worked first time !!!  :D



My bet is: When you use it to switch the actual compressor, EMI from the relay contacts will disturb you circuit, e.g. the counter skipping an amount of clock pulses, and the switching cycle might be faster or otherwise unexpected.

If you will have done everything right, it'll work and prove me wrong  >:D
Safety devices hinder evolution
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf