EEVblog #680 - Mailbag

[coppice]

Dave, did my old eyes just see an 8-inch floppy disk on your shelf there?
Also, i spotted a few males. I think they're winners...    or not... 

I'm amazed that an early '70s PDP/8 was less than $600.

Now somebody is going to tell me you could buy a house for $600 back then. Fecking inflation! 

$600 bought you the bare CPU of a very simplified PDP/8. $600 wouldn't buy you a house in those days, but it was quite a lot.

It might be more interesting to compare the $572 price tag for the PDP/8 CPU with the $299 price tag of a digital multimeter in the same magazine. The think how expensive a simple multimeter was at that price. In those days a 100MHz scope was about a years salary for a fresh grad.

[Fungus]

I'm amazed that an early '70s PDP/8 was less than $600.

That would be the bare CPU with nothing more. The price would go way up as soon as you add storage, memory, terminals, etc.

[mario001]

Hi Dave, hi all,

thanks for the review of my isolated USB UART interface!  I didn't put it under a specific license, but yes it is open hardware and anyone may use the whole thing or parts of it freely. The documentation and some additional pictures can be found on my homepage, www.mario001.de (german language). I will soon upload the english translation (that was seen in the video), too.

@eV1Te: Sorry I do not sell the interface, but I still have some unpopulated PCBs. Just send me a PN 

Regards, Mario

[guido]

Hi Dave,

i recognise the meter in the magazine. If you could scan the page, i would be grateful.



I have two, 5.5 digit and very nice panaplex displays. Much nicer than the photo. It is quite a novel design for the age. The auto ranging is very slow, it takes nearly a second to change a range.

Unfortunately one has a broken panaplex display (+8 section). Got a replacement but that did not last long. I could change it to an LC display (for the moment, sub pcb which can be swapped). There is a whole array of counters daisy chained, so instead a small micro and a hardware counter could count the value for one conversion and display it on an lcd. A small pic would be sufficient. But i don't really need it working...

I replaced all caps in both, they were leaking badly. Still need to calibrate them agains the HP in the photo.

[kc0ngu]

Hi
Thanks for the PCB holder review
There are groves top and bottom to keep the board from droping down.
Made some up there for sale on
https://www.tindie.com/products/Z2instro/pcb-assembly-holder/?pt=directsearch

Regards
Leo

Much appreciated that you put your tool up for sale for anyone interested. However, the Tindi price frankly is not very favorable.

Flat drill vices with similar 4-inch clamping width can be bought almost anywhere (i guess) for similar or less that price (like this one with rubberized jaws ). Aside from being more robust, the clamping area of those vices is not obstructed by the worm drive. I am not saying that your little tool is not useful. But for the given (Tindi) price i would rather purchase a drill vice, which is equally suited as a (heavy-weight) PCB holder.

If you already have a drill vice with flat metal clamps, just get some cheap magnetic rubber or nylon jaws (like this one) and you got yourself a PCB holder...

(Btw, I actually use sometimes a drill vice similar to this one as PCB holder. However, this model only has a clamping width of 80 mm / 3 inch.)

Not sure I understand what is unfavorable about $30.
Most (all?) Tindie sellers are small vendors, often making the product they sell at home or out of a small business unit, they are not mass manufacturers or able/want to sell via Amazon, competing with Amazon or worse still Harbor Freight (in USA) is pretty tough for the small guys.
Go on release the moths splash some cash and help a small guy out 

[m100]

40 min 5 secs in, left hand page "BBC experiments with digital tv recording"   That is some two decades before Digital Betacam!

TDA 2020 mentioned just to the left of that article, that had some really funky leadout and packaging with staggered pins and a copper block to get the heat away from the die

http://www.donberg.ie/pics/t/tda_2020.jpg

Love this look at things decades ago!

[eV1Te]

Hi Dave, hi all,

thanks for the review of my isolated USB UART interface!  I didn't put it under a specific license, but yes it is open hardware and anyone may use the whole thing or parts of it freely. The documentation and some additional pictures can be found on my homepage, www.mario001.de (german language). I will soon upload the english translation (that was seen in the video), too.

@eV1Te: Sorry I do not sell the interface, but I still have some unpopulated PCBs. Just send me a PN 

Regards, Mario

Too bad you are not selling them, I liked the functionality.
I am not sure if I have the time to find and then purchase all the components required before I can even start soldering it. Do you still have all the components at home (at least the hard to find ones like the FTDI chip, the DC/DC converter and opto-isolator)? Could you could sell it as a kit?

[cimmo]

Yes please for "Wayback Wednesday". 

[Involute]

Hi
Thanks for the PCB holder review
There are groves top and bottom to keep the board from droping down.
Made some up there for sale on
https://www.tindie.com/products/Z2instro/pcb-assembly-holder/?pt=directsearch

Regards
Leo

Much appreciated that you put your tool up for sale for anyone interested. However, the Tindi price frankly is not very favorable.

Flat drill vices with similar 4-inch clamping width can be bought almost anywhere (i guess) for similar or less that price (like this one with rubberized jaws ). Aside from being more robust, the clamping area of those vices is not obstructed by the worm drive. I am not saying that your little tool is not useful. But for the given (Tindi) price i would rather purchase a drill vice, which is equally suited as a (heavy-weight) PCB holder.

If you already have a drill vice with flat metal clamps, just get some cheap magnetic rubber or nylon jaws (like this one) and you got yourself a PCB holder...

(Btw, I actually use sometimes a drill vice similar to this one as PCB holder. However, this model only has a clamping width of 80 mm / 3 inch.)

Frankly, I'd prefer Leo's vice as it keeps the board much closer to the bench surface and takes up less space than the drill vice.

[VK3DRB]

You can freeze frame the video in HD and read most of that article on engineers being loners.

By the way, it is largely true that engineers are often people with deep social awkwardness. That is one reason why a lot do engineering or computer science because they think they only have to deal with stuff rather than people. A generalisation of course. I was quite unusual in that whilst I was studying electronics engineering at uni, I was into discotheques.