Well I can't see the fluff with a tester like this, especially with the price and UI
The TL866II Pro "eeprom" programmer that also does flash, bios, etc. also has a chip tester as well for 300 different logic IC.
Totally different devices to support different use cases. For example, the first thing I looked up after reading your post were the RAM chips for a Tandy/Radio Shack Color Computer 1: 2104 (4Kx1) and 4116 (16Kx1). Both are supported by the Retro Chip Tester, neither by the TL866II Pro. I'm sure there will be other examples, because the focus of the products is different.
Yes, the UI leaves a lot to be desired, as I eluded to previously. Had I the free time available, I'd probably just make my own retro chip tester. It's not like I have that many retro computers, thankfully.
Small added Rabbit Burrow Getting square and flat.
Now I just need a better test indicator, smaller holder and or a larger surface plate and a .....Laser Interferometer.
Small added Rabbit Burrow Getting square and flat.
Now I just need a better test indicator, smaller holder and or a larger surface plate and a .....Laser Interferometer.
FTFY
Anyway - I got a magna cum laude and I am supposed to be satisfied with it. I can still publish some extra chapters on my webpages ...
...
whereupon he's all like:
ch_scr — Today at 6:05 PM
fuck
you know I have to make me one as well?
thanks I guess
And he means from scratch out of his parts bins, just because...
But he posted a vid showing how to do what I wanted with the nanoVNA; and damn if he didn't get me back: Next in my yoobToob queue was this little gem, which sucked up another half-hour of my life...
...
Some more work on the HP 5381A. The thing uses a good old SN7446 as the display decoder and this thing appears to eat displays. The question is why. Well looking into it in detail of the design, the SN7446 is the digit driver and is open collector. The digit mux is done using some discrete generic PNP transistors. The whole thing is current limited by a single 47 ohm resistor per segment.
Throwing all this into LTspice results in this with a crude approximation of a 2.36v drop LED:
So what does this tell you? Well the standing current is 53mA through each of these segments! Even if pulsed that's a bit much for vintage LEDs so no wonder they were blowing up.
So what do we do here? Well I've ordered a bunch of new Kingbright ones which are significantly more efficient so I'm replacing all the displays and the 47 ohm resistors with 220 ohm ones. As the rest of the counter runs luke warm but the display board runs hotter than satan's bollocks, this should reduce the stress considerably!
Edit: considering bagging a Duratool desolder station for this one as I don't fancy having to braid all these displays out https://cpc.farnell.com/duratool/d00672/desoldering-station-uk-eu-plug/dp/SD01384
Oh and what's that lurking on top? A 475 and an E3630A. Deja Vu here
...
whereupon he's all like:
ch_scr — Today at 6:05 PM
fuck
you know I have to make me one as well?
thanks I guess
And he means from scratch out of his parts bins, just because...
But he posted a vid showing how to do what I wanted with the nanoVNA; and damn if he didn't get me back: Next in my yoobToob queue was this little gem, which sucked up another half-hour of my life...
...Found two reasonable "primary" source for info on the dg-mos fet probe:
T. Hirschbüchler Bachelor Thesis on the "Design of a low-cost 1 GHz Active Probe" with "conception, construction and evaluation"
https://content.instructables.com/ORIG/FQZ/1QZP/IPJTFO82/FQZ1QZPIPJTFO82.pdf
and the layout from elektor with the gimmick-cap on the pcb:
https://www.elektormagazine.com/files/magazine/2004/dolo/040108-PCB.pdf
Some more work on the HP 5381A. The thing uses a good old SN7446 as the display decoder and this thing appears to eat displays. The question is why. Well looking into it in detail of the design, the SN7446 is the digit driver and is open collector. The digit mux is done using some discrete generic PNP transistors. The whole thing is current limited by a single 47 ohm resistor per segment.
Throwing all this into LTspice results in this with a crude approximation of a 2.36v drop LED:
So what does this tell you? Well the standing current is 53mA through each of these segments! Even if pulsed that's a bit much for vintage LEDs so no wonder they were blowing up.
So what do we do here? Well I've ordered a bunch of new Kingbright ones which are significantly more efficient so I'm replacing all the displays and the 47 ohm resistors with 220 ohm ones. As the rest of the counter runs luke warm but the display board runs hotter than satan's bollocks, this should reduce the stress considerably!
Edit: considering bagging a Duratool desolder station for this one as I don't fancy having to braid all these displays out https://cpc.farnell.com/duratool/d00672/desoldering-station-uk-eu-plug/dp/SD01384
Oh and what's that lurking on top? A 475 and an E3630A. Deja Vu hereSo totalling it up, did you make or loose money buying and selling the same gear over and over again?
Also on getting a desoldering station.
Some more work on the HP 5381A. The thing uses a good old SN7446 as the display decoder and this thing appears to eat displays. The question is why. Well looking into it in detail of the design, the SN7446 is the digit driver and is open collector. The digit mux is done using some discrete generic PNP transistors. The whole thing is current limited by a single 47 ohm resistor per segment.
Throwing all this into LTspice results in this with a crude approximation of a 2.36v drop LED:
So what does this tell you? Well the standing current is 53mA through each of these segments! Even if pulsed that's a bit much for vintage LEDs so no wonder they were blowing up.
So what do we do here? Well I've ordered a bunch of new Kingbright ones which are significantly more efficient so I'm replacing all the displays and the 47 ohm resistors with 220 ohm ones. As the rest of the counter runs luke warm but the display board runs hotter than satan's bollocks, this should reduce the stress considerably!
Edit: considering bagging a Duratool desolder station for this one as I don't fancy having to braid all these displays out https://cpc.farnell.com/duratool/d00672/desoldering-station-uk-eu-plug/dp/SD01384
Well motherfucker... I actually suggested that you might need to replace those ballast resistors if you changed the color... and that really, they should be changed anyways (thinking carbon composite, etc)... which would've put you on that very track.
But then I thought I was just getting too outre' in my random "stream of consciousness" and almost immediately edited it out for brevity's sake.
mnem
Even when I'm right, I can find a way to be wrong...
Edit: considering bagging a Duratool desolder station for this one as I don't fancy having to braid all these displays out https://cpc.farnell.com/duratool/d00672/desoldering-station-uk-eu-plug/dp/SD01384Yeah, bag one of those desolder stations, you'll wonder why you stuck with braid for so long, honestly it is a good investment.
...I do this for love now not for survival, plus if I don't do it the devil might make use of my idle hands
...
whereupon he's all like:
ch_scr — Today at 6:05 PM
fuck
you know I have to make me one as well?
thanks I guess
And he means from scratch out of his parts bins, just because...
But he posted a vid showing how to do what I wanted with the nanoVNA; and damn if he didn't get me back: Next in my yoobToob queue was this little gem, which sucked up another half-hour of my life...
...Found two reasonable "primary" source for info on the dg-mos fet probe:
T. Hirschbüchler Bachelor Thesis on the "Design of a low-cost 1 GHz Active Probe" with "conception, construction and evaluation"
https://content.instructables.com/ORIG/FQZ/1QZP/IPJTFO82/FQZ1QZPIPJTFO82.pdf
and the layout from elektor with the gimmick-cap on the pcb:
https://www.elektormagazine.com/files/magazine/2004/dolo/040108-PCB.pdf
That link is borked (at least for me); it may be behind a paywall. I've attached the .pdf below.
Also, I actually found that article while doing my own research; however I didn't agree with two primary features of his construction technique:
1), his pogo pins are just too long. Everything I've read on the subject aside from his article indicates that ~5mm or less is the ideal length here.
And B) the pin spacing is just ridiculously too wide (yes, I understand the reasons) to actually be a useful probe for most of the kind of stuff you'll use it for. The really good thing aboot the 60dbmcom probe is the big pads for soldering pins to; you can easily reconfigure to match almost any needed pin spacing.
https://www.ebay.com/itm/174764316127
There's also this one; it supposedly has specs from the actual device (not just copied from the Elektor article), and I like that the total signal path is as short as possible; however, it was 2x the price and completely unreasonable delivery time. Also it does not use the gimmick capacitor and no pad for GND pin, which is part of the reason the Elektor design uses a dual-gate FET.
mnem
That's about 45 mins from here. Nope not got the room!
I don't think I mentioned this here, but those in the UK might be interested in:
TEKTRONIX 561A Vintage Oscilloscope - Fantastic Condition, Shenley, Hertfordshire £100.00 Collection only at Shenley Herts (J22 on M25)
https://www.gumtree.com/p/hobbies-collectibles/tektronix-561a-vintage-oscilloscope-fantastic-condition/1411056157
The photos do look good.