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Test Equipment Anonymous (TEA) group therapy thread

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Cubdriver:

--- Quote from: Vince on June 24, 2022, 09:11:06 pm ---
--- Quote from: Cubdriver on June 24, 2022, 08:46:23 pm ---Poor counters can’t get no love….  :'(


-Pat

--- End quote ---

Just curious : the two instruments at the bottom... they have  a mix of period knobs, and next generation plastic knobs found on later HP TE... did HP create these hybrid monsters, they came from the factory like that  ?:!  or did you just put these knobs yourself to replace missing ones ? Not judging... just curious to learn... if HP did that themselves, I wanna know...

--- End quote ---

Funny that in all the years I've had them I never noticed that.  Yes, they did come like that, with the larger, better 60s style knobs for the function and range switches, and the blech (IMO) 70s style knobs for the input level setting.  So yes, HP did indeed create these hybrid monsters.

-Pat

Vince:

--- Quote from: mansaxel on June 24, 2022, 09:14:49 pm ---
--- Quote from: bd139 on June 24, 2022, 09:08:33 pm ---
--- Quote from: Vince on June 24, 2022, 09:04:23 pm ---I don't  understand the comparison between the two ? I mean they are just different things. 4000 series has a voltage range of 3 to 15V. 74HC / HCT if I believe the datasheet I just pulled, is 2 to 6V.
I understand your points, taken...but if I need to supply the logic for whatever reason above 6V, I am screwed with 74-anything.
Or if the circuit doesn't have stable supply voltage and the logic cheap needs to be able to operate with a changing supply voltage ?!  :-//

--- End quote ---

It's probably cheaper now to just chuck a 78L05 in the circuit and be done. That will handle both problems for pocket change.

--- End quote ---

Don't be so .. practical . That's not fun.  :-DD

--- End quote ---

Come to think of it, I have one practical / real world example where 4000 chips were favored instead of 74. Had to fix the electronics in a consumer Expresso machine, and let me tell you the cost cutting on the board was such that using a 74XX + a 7805 chip (and caps to go with it) just was NOT an option !  :-DD

Here, found a pic of the board I took back then.  It's from a " MAGIMIX  M150 " coffee machine.

The board takes mains in.

Power supply : single diode / half wave rectification, then one tiny Zener with a beefy series resistor, and one small smoothing cap. Done !

Logic : two 4000 chips.

One is a counter, its clock input is driven by the mains !!!  There is only one high value resistor to limit the current, and I guess they make use of the internal input protection diode to rectify the mains  :wtf:

Then the second chip drives a Thyristor that powers the water pump of the coffee machine.  The Thyristor keeps blowing, replaced it once, pump ran for a few seconds then it blew again... thinking the pump might be leaking internally, water getting into the motor and shorting it, overloading the Thryristor ?! My best guess  anyway  :-//



dl6lr:
Just wanted to say hello again.

Back from holiday. I had a ride on my bicycle from Magdeburg to Hörstel along the Mittellandkanal here in Germany. All together about 460km. On my way back I stopped in Osnabrück and found a "Yes, it's bicycle repair man" with a bicycle washing machine. So I had my wifes and my bike washed by a smart young man, see attached photo. Very convenient! The guy asked me because of all the dust: Have you been in the Sahara?  :-DD

No TEA but I avoided some WEA (washing equipment acquisition), as the washing machine flicked the RCD before holiday and refused to turn the motor afterwards. So I disassembled and cleaned the motor and found the brushes to be still in good condition (but a lot of dust around) and it turned fine on the variac. So I concluded to search for the issue in the electronics. I found one TRIAC to be suspicious and ordered a replacement. Changed yesterday after returning home and now the machine is working fine again.

tautech:

--- Quote from: Vince on June 24, 2022, 09:15:23 pm ---
--- Quote from: bd139 on June 24, 2022, 09:08:33 pm ---
--- Quote from: Vince on June 24, 2022, 09:04:23 pm ---I don't  understand the comparison between the two ? I mean they are just different things. 4000 series has a voltage range of 3 to 15V. 74HC / HCT if I believe the datasheet I just pulled, is 2 to 6V.
I understand your points, taken...but if I need to supply the logic for whatever reason above 6V, I am screwed with 74-anything.
Or if the circuit doesn't have stable supply voltage and the logic cheap needs to be able to operate with a changing supply voltage ?!  :-//

--- End quote ---

It's probably cheaper now to just chuck a 78L05 in the circuit and be done. That will handle both problems for pocket change.

--- End quote ---

Yes again not saying 4000  is better, just saying it's different and it thus allows potentially to do stuff you can't do with a 74 (alone).
It's up to the designer and bean counters to decide if it makes more sense for a particular project to go one route or the other. But at least 4000 series gives you options, and options are always good...  8)

--- End quote ---
These days we have more options like lower threshold MOSFET gates so we don't need to use level convertors so much and in this realm is where 4000 were so beneficial.
Lots of fun playing with glue logic that most can't be bothered with these days and instead just use a micro which is fine if you can program.  |O

Vince:

--- Quote from: dl6lr on June 24, 2022, 09:28:20 pm ---Just wanted to say hello again.

Back from holiday. I had a ride on my bicycle from Magdeburg to Hörstel along the Mittellandkanal here in Germany. All together about 460km. On my way back I stopped in Osnabrück and found a "Yes, it's bicycle repair man" with a bicycle washing machine. So I had my wifes and my bike washed by a smart young man, see attached photo. Very convenient! The guy asked me because of all the dust: Have you been in the Sahara?  :-DD

No TEA but I avoided some WEA (washing equipment acquisition), as the washing machine flicked the RCD before holiday and refused to turn the motor afterwards. So I disassembled and cleaned the motor and found the brushes to be still in good condition (but a lot of dust around) and it turned fine on the variac. So I concluded to search for the issue in the electronics. I found one TRIAC to be suspicious and ordered a replacement. Changed yesterday after returning home and now the machine is working fine again.

--- End quote ---


A washing machine for bicycles ?!  :o

Didn't even know such a thing even existed, thanks... you learn a little something every day they say...

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