Snap, crackle and pop - heating pipes

[MdB]

Well, today hasn't been a waste, thanks to MdB. I've learned something new.

In return, do you think you can tell me why 2 x 74HC74Ns have just blown themselves up on my test bench?

 

[Penners]

In return, do you think you can tell me why 2 x 74HC74Ns have just blown themselves up on my test bench?

Well, it's not my normal area of expertise, but with a positive-edge trigger, could you have asking it to flip when it should have flopped?

 

[MdB]

Well, it's not my normal area of expertise, but with a positive-edge trigger, could you have asking it to flip when it should have flopped?

Well the ~Q output was both flopping fine but the Q output flipping well wasn't. Time to replace them both.

 

[Penners]

That's certainly what I would advise.

Feel free to ask any time.

 

[Flyfisher]

They are stretched before being welded.

Blimey - they must use something a bit more substantial than my fence-wire puller then. Does this mean, though, that if something breaks then a train might run out of 'elasticated' track before reaching the terminus station? :shock: :lol:

Thermite - ah, fond chemistry labs memories

Well done Penners on the logic quiz, I didn't think discrete 74-series chips were used much these days?

 

[MdB]

That's certainly what I would advise.

Feel free to ask any time.

Pah, shouldn't have listened to you. Changed the 74HC74s and it didn't fix it. Turned out to be a short on the input of the MAX4527 (which I should have spotted).

I didn't think discrete 74-series chips were used much these days?

Its a 10 year old design but the 74 series chips still have their uses to solve some simple problems. Most of my logic design is now in FPGAs but they can be overkill for the simple stuff.

 

[Penners]

I didn't think discrete 74-series chips were used much these days

No, mostly crinkle-cut nand gates, in my experience.

 

[Penners]

Thermite - ah, fond chemistry labs memories

Ah, fond bank vault memories.


I was joking, officer. Honest.

 

[chuckey]

I think it all went down hill when those nasty little plastic chips came in. Give me triode-triode logic any time! a view I would expect Period Property board readers to concur with. Nothing quite like the smell of a 1960s counter warming up.
Frank

 

[Lime]

It's years since I used TTL & CMOS.
I've still got hundreds stored in my office (still in RS wrapping) that I can't bring myself to dispose of.
I never used valves for logic, much too large, counting up to a 1000 heated the house.
I know what you mean by smell though.
Valves have a life of their own.

 

[Flyfisher]

Valves still have their place - guitar amps for one. I believe they are also still widely used in high power RF amps, where their high voltage capability is an advantage.

 

[AMc]

Thanks for the tips people and the trip down NAND, OR AND NOR memory lane. I learn't A/S electronics at the end of the eighties when we were taught to use transistors but you could almost always use an IC to do the whole circuit cheaper and better.

You can't beat the sound of an overdriven Marshall tube amp and a Gibson Les Paul, but I love the smell of burnt power transistors in the morning...

I'll post back when I've had the time and nerve to pull up that board.

 

[Penners]

I think it all went down hill when those nasty little plastic chips came in.

It was the same at our local fish shop.

It's years since I used TTL & CMOS.
I've still got hundreds stored in my office (still in RS wrapping) that I can't bring myself to dispose of.
I never used valves for logic, much too large, counting up to a 1000 heated the house.

Lime, you didn't ever work for EEV in Chelmsford by any chance? A great friend of mine did.

 

[Penners]

You can't beat the sound of an overdriven Marshall tube amp and a Gibson Les Paul.

Now you're talking my language (at last)! Stuff your flangers and fuzz-boxes - just wind the amp up to 11!

 

[AMc]

It's one louder....

 

[Penners]

Pardon?

 

[AMc]

Sorry I can't hear you above the ringing in my ears

http://www.youtube.com/watch?v=akaD9v460yI

 

[Lime]

Lime, you didn't ever work for EEV in Chelmsford by any chance? A great friend of mine did.

No, the only place of similar ilk I worked for was GEC Hirst Research Centre back in the 60s.
That was a wonderful place for someone like me who enjoyed anything electrical.
There was a "dump" where all the redundant stuff from the labs was scrapped. Nearly every lunchtime some time was spent to have a good old rummage.
There was life-testing going on there too so used valves were available for nothing, boxes of them. Several of my colleagues used upto 8 KT66s wired as triodes in parallel push-pull for their home-made hifi amps.
I was a bit more particular and used KT88s.

Those were the days.
Sad about GEC isn't it?
Then the biggest electrical company in the world, now next to nothing.

 

[Lime]

Valves still have their place - guitar amps for one. I believe they are also still widely used in high power RF amps, where their high voltage capability is an advantage.

Most transmitters now use solid state.
I agree about guitars and valves, something to do with the 2nd harmonic I believe.

The only ubiquitous valve of sorts still in service is the magnetron. Nearly everyone has one.

 

[chuckey]

On a head count, I would say (at present) that the CRT would win on numbers, as many houses have 2+ TV sets, and a PC and only one Microwave.
Frank