Mats Engstrom
@matseng
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Coder by profession, electronics tinkerer as hobby. Been back in .SE for a while now after working&living in .AE, .MY & .TH for 12 years. :sadface:
Stockholm, Sweden
Joined April 2007
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Hack tip of the day. When you don't have any female connectors/adapters and you need to connect two "DB" connectors to each other you can use small pieces of insulation from a mains wire. Put them on the pins and then jam Dupont jumpers into them.
#notPrettyButWorks
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I just got this from the library. A book describing how to build mid-70's TV-games out of TTL logic gates - no microcontrollers required here. Thanks
@anachrocomputer
for the tip!
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I really love this project. An UART receiver made out of only transistors.
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It looks like the footprints for the resistor arrays on the PCB turned into some kind of flying alien spaghetti monsters...
^__^
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So what's your take on converting an 8-bit binary value to 3-digit decimal if you don't want to use a microcontroller?
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If this is not a good looking PCB I don't know what is. Hand taped traces and what looks like transparent solder mask. And by some reason it works without a ground plane... ;-)
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When I solder up a protoboard or hook up something on a solderless breadboard I like to have pinouts on paper. Making one specifically for each project is tedious. What do you think of a webservice where you can select parts and it spits out a merged pdf? Usable or Meh?
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It's amazing that this tiny thing can take 5 to 14 volts in and deliver 0.6 to 5.5v at 6 amps (buck only). It even have a sense input to compensate for lead droop. They are like 10x the price of the cheap Chinese boards but I would never put one of those in anything expensive.
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By scanning though all nets on the PCB and highlighting them one by one it looks like some kind electrical arcs travelling over the board. I imagine that this is pretty much how a Gerber photo plotter would look like except that works on individual segments, not entire nets.
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This is a compact and easy way of increasing the current drive capability of a DIP IC. Just stack a bunch of them ontop of each other. ;) Here a +5 to -9v @ 200mA converter which is not bad for a simple charge pump....
From
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It's dangerous to sell items at an auction without a reservation- or starting price. I just got 19 pcs of 4PDT 24 volt Siemens relays for for a total of $1 + $5 shipping. I do actually feel a bit sorry for the poor seller....
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It's somehow amazing that something as itty-bitty as this fuse can handle 5 amps. (This particular fuse is 3 amps, but the series ranges from 0.5 to 5 amps)
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A post from
@rabid_inventor
reminded me of this project I did 10 years ago. It was kinda fun to put all thru-hole parts *inside* the PCB. The board almost got down to a SMD design in height. The paperclip CR2032 battery holder worked quite well.
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This is how an old school electronics shop should look like. From the city of George Town on the island of Penang, Malaysia. I wish I had a wall of component drawer like that....
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Every time someone draws a schematic this way a cute kitten dies.
#ControversialOpinonOfTheDay
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Ok. Done... Looks like crap - but what to expect at this pitch and "old-people" hands. I've buzzed out all connections for shorts and continuity where it should be. But I don't know until I've actually tried to use it... ;-)
Have I told you how much I dislike BGAs? :-) The balls at the edge was easy enough. But I'm dreading the inner rows that remains. It's after midnight now, so I think I'll tackle those tomorrow. PCB breakouts might be easier... Maybe...
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Have I told you how much I dislike BGAs? :-) The balls at the edge was easy enough. But I'm dreading the inner rows that remains. It's after midnight now, so I think I'll tackle those tomorrow. PCB breakouts might be easier... Maybe...
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Yes! My scope is back in business again. After bodgeing on a new 1.1v DC-DC converter onto the original bodge it seems to work just fine. A $3K scope saved by a $10 module.
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Where? How? Why? How could I completely have missed that Reverse Mount Tactile Switches exist? ;-) They solve so many problems. I just have to get a bag of them as soon as possible.
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My old electronics side cutters are approaching their end-of-life and I'm debating with myself if high-end tools are a waste of money or not. Is a $120 Lindstrom that much better/durable than a $25 Knipex or a $5 "China special". Maybe Knipex is a good middle ground?
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This machine control system looks similar to the traffic junction control box I found in Georgetown, Malaysia. It's cool to be able to program and setup a system with physical plugs instead of code.
知り合いの加工屋さんの機械
こんなスイッチング基板で操作してたとは知らなかった
これがまだ現役！
すげーかっこいい
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My purchase-finger is really twitching when I see this tiny display. But for a dollar a pop I'd like four digits instead of three.
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Yes! I scored 58 kilos (128 lbs for those who are metric-challenged) of 74-series logic ICs for the somewhat pricey sum of $300 at an auction site. Pickup only - luckily it's just a bit over one hour by car away. The wife was ok with me spending this on "old crap" :)
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I just got a Z8671 - a Z8 (somewhat related to Z80 but not hard- or software compatible) microcontroller with a bit of built-in RAM and a BASIC interpreter in internal ROM. All it needs is a crystal, 5volts and a terminal (or FTDI adapter) and you can code BASIC applications.
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We can bitbang USB and VGA on a decades old ATTINY85, on a cheap RP2040 we can bitbang DVI. But I've never seen a project that bitbangs the CC lines on USB-C for PD (Power Delivery). That is always done with a dedicated IC. Is that really so complex/hard that it can't be bbanged?
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Protip of the day: Unless you need the extra sliver of board for routing it can be a good idea to extend the copper of the holes for 90-degree pinheaders all the way to the pcb edge. Then you can use regular straight headers if you're out of the more expensive 90-degrees headers.
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Two IM6100 CPU (PDP-8 on a chip) and two IM6101 PIO - unfortunately the seller didn't have any corresponding UARTs. But this is good enough to start building a PDP-8 with. Just add 32K RAM and I'm almost done already. :)
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Sadness galore. It's just about 5 years ago that I unpacked my shiny and new $3K
@RohdeSchwarz
oscilloscope being my pride and joy on my lab bench. Today it suddenly rebooted and after that I just get the fan and a black screen at power on. ;-( Not good.
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Ohhhh... I wonder if I could get this as an attachment to my plain old trinocular AmScope? That'd be amazing! Imagine how much less hassle it would be when checking hand-soldered QFNs.
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Am I just an old grumpy fart when I think that this style of schematics that became very common the last few years is not really a proper schematic but more is just a "netlist with pictures"?
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I just realised that after 45 years of electronics tinkering I only know a few of the Ohms law (& power) permutations by heart. P=I*V, P=R*I² and I=V/R. The rest I can quickly figure out in my head. What about you? - are you as "ignorant" as me on this subject?
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Found this video on YT-shorts. Most commenters claimed it was fake or just played in reverse(?). It looks somewhat plausible to use paste diluted in a lot of flux, but I'm not 100% that it will be perfectly good due to too few solder-balls for each joint.
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I sent for a test PCB after the discussion about via placement in power traces. It tests the resistance in 5mil/0.5mm/1mm traces with and without vias in five configs. I'll also use it to test crosstalk in 5/5mil and 5/40mil spaced busses. Also test holes for M2 screws.
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I'm not 100% convinced that it's worth the time to solder up, and debug, 89 pcs of 74-series ICs to emulate an AY-3-8910 sound chip. The most interesting part of it probably was to get it working in sim, but I'm really tempted to do it since it's such a silly thing to do. ^__^
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You people remember that I bought 58 kilos of NOS 74-series ICs a few days ago? Today I picked them up. After sorting through a few tubes with regular stuff I found a full tube of these puppies - the highly coveted 74181 ALUs. :)
#TreasureHunt
@Monsonite
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One month ago I ordered this book from Amazon US arriving yesterday. After reading a couple of chapters I'd say it's a nice book definitely worth its price ($34 w shipping & import VAT) for anyone remotely interested of building a 8088 computer from scratch.
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This is my balcony after sorting almost 1000 tubes of ICs into piles of different major functional groups. The brown stuff on the floor are petrified rubber bands. ;)
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From Mikes new video... I've seen this "space saving design" a couple of times before. I have a hard time to decide if it is really smart, or just a bit over the top. :)
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How would you do a via off a power trace? Here the trace is 0.6mm/24mil. Doing it like A will reduce the width if the trace quite a bit, but the distance is not long so maybe it doesn't really matter? B seems a bit silly and looks like a stub (but isn't). C maybe?
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I just have to use this old meme again:
-How many ground stitch vias do you want?
-Yes.
This is not a GHz microwave -level board, just a 48MHz little cheap devboard for a microcontroller. ;-)
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Ahh. The wonders of international courier shipping. At 1 pm Wednesday I ordered 10 packs of 10 each of the "Shrug switch" (Reverse mount tactile) from Mouser. They got shipped from Texas, USA all the way to my doorstep in Sweden and delivered at 10 am Friday.
:-)
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From the department of unnecessary knowledge: This type of connector is nicknamed "sugar cubes" in Sweden. I'm actually not certain of the correct official name for them so sugar cubes is good enough for me ;)
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The EMZ1001 processor from the old Eastern Bloc is 4/8-bit internally having a 8-bit external databus and 13 bits of address bus. It also have a rather unique instruction - "EUR" that switches an internal timer between 50/ 60 Hz And it runs on +9 volts just to be special ;-)
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This screenshot might be a worthy contender to the "Annoying things while laying out a board" -competition. ;-)
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I wonder how many LEDs there are below the diffuser. The IC could possibly drive up to as many as 30 Charlieplexed LEDs but I doubt that it is that many. But probably more than 6 driven directly from the GPIOs.
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Hey
@RueNahcMohr
, this design idea might come in handy some day to enhance some projects silliness ;)
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I was thinking of getting a logic analyser and of course looked at a 16 ch Saleae. But.... Aaaaaahhhhh! They're $1500 nowadays. Ten years ago it was $299 (lower sample rate back then, but the speed of the parts used have gone up over the years, so....)
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I'm fixing a Lenovo X13 - replacing the LCD that apparently "had an accident" and also the fuse for the LCD backlight. The fuse is on the backside of the CPU board and is 0402 but looks significantly smaller than that. Aaaahhh....
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I picked up a bundle of Eproms just to stock up if I ever would need some, and these three beauties were among them. Nice ceramic and gold Intel 8087 math co-processors. Not sure what I'm going to do with them, but at least they're safe from gold scrappers now.
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Black soldermask looks sexy when clean. But trying to get rid of evil flux residues without the right solvent and a ultrasonic cleaner makes it look really bad. Here I tried using detergent&hot water, CRC contact cleaner and IPA. Looks a mess. Maybe paint thinner will work? MEK?
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[1/2] My PCIe test boards arrived today. Works like a charm even if they are a bit thicker than the spec's nominal value. And they are easy to insert even if the card edge is not beveled. Definitely start using PCIe for busses instead of regular pin headers.
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Tennis for Two (1958) was one of the first "computer games". The power supply might not be the worst, but for sure really simplified for a 4-voltage pos/neg output PSU. A virtual ground and resistive dividers won't be stable. But apparently good enough.
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It's starting to looks like something... Not sure what - but at least something ;-) Freeformed Intel 80186 on a freeformed 42-lane backplane bus. Now I just have to connect latches, ram and eprom and a oldskool 16450 part. Keeping fingers crossed that it will work in the end.
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I probably wouldn't have designed a "one chip debouncer" like this. I'm just like "why"? :-)
And directly shorting a (even a small value) cap like that is a recipe for eventual disaster.
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If I was into PC modding today (the last time I did mod a case was back in the 80286-era so that doesn't count) I'd definitely would have a CPU load panel like this one in my machine.
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Sometimes sellers, especially from China, adds a little gift in the packages like a bookmark or a small bag of candies. The guy that sold me a bunch of electronics books added some random EPROMs. That's a first for me. But still appreciated 👍
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This is an AOI (And-Or-Invert) gate. I've read that they, in the past, were a rather common construct in digital logic and very useful. But I've never seen any elaboration on why and how a gate combo like this would be used. Are there any specific usage cases?
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Damn.... My 3.3volt 74HC based 1.8MHz crystal oscillator tend to go into 3rd (or even higher) overtone mode when disturbed. Better read up solutions in AoE (Horowitz). I guess a series resistor reducing drive current will help but AoE might have a better solution.
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The end result of careful and precise soldering of magnet wire on a PCB. I would not have the patience for this. But it looks very nice. :)
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Alright... The memory card with the annoying PLCC flash memories works fine. Here I'm running some test code on a Teensy that fills the RAM (6MB) & FLASH (768K) with random data and verifying it. Then enters a 1960s computer flashing lights mode just to look cool ;-)
#SUBLEQ
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This solderless breadboard with an integrated IDC connector is a bit interesting. It looks like it's made for some special application considering the labelling on the board. Googling with some relevant keywords didn't give me any good hits. Do you recognise it?
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I just remembered that I five years ago bought a IBM PC/5150-kit from and I haven't built it yet. I probably should do that some day soon or else it might be another five years before I stumble upon it again :)
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Today's delivery from an eBay seller from Bulgaria. A dozen unobtanium 74LS323 for my Apple ][ floppy controller. Two Russian 8080 CPUs, and ~1000 core memory ferrite rings.
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Am I a total cheapskate? I need three PCBs with U1 (latch) plus U3 (tristate buffer) and one PCB with (U7/U8 counters) plus the U3 (tristate buffer) and instead of ordering two different designs of five PCBs each I make it so I can either populate U1 or U7/U8 on the same PCB. ;-)
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The baggie with 2000 of these jumpers arrived today. Even if I will be splitting them with two others I think I have enough to last quite a while. :)
These seem very nice for hooking on test clips, probes and power to a PCB. If the translator is correct they're less than a dollar for 20 pcs. I have to find these locally in EU or AliExpress and get a few handfuls to be used in all my future projects.
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Alright, I'm back building more boards for the CHIP-8 system. Here I've piggybacked 16 pcs of 74LS374 latches. This board is the stack & stackpointer module and will have one more "tower" on it. The registers board will also have two of these towers to be triple(?) ported.
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For a measly $8 you can get a "laser harp" kit. That's really cheap even considering that the microcontroller looks like some half-damaged pull from an old PCB :-) :-)
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@SimoneGiertz
@Workshopshed
The security at Bangkok airport made me empty out my carryon bag with this in it :-()
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Do we have enough rounded tracks to appease the "Ugh, 90 degree angle bad"-crowd? ;-) And more importantly - have any of you peeps ever done anything with SUBLEQ? This is the RAM/FLASH board of a 24-bit subleq machine I'm designing just for fun.
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I've never seen this before, but I'm not surprised they exist. Ampere meters that replace the top screw-in part of the fuses in the mains distribution box. (Made for the particular ceramic fuses we used to use here once upon a time).
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I found a really nice experimental project at github - generating VGA video directly from an
#ESP32
. Here I just hooked up the ESP via three resistors to a VGA cable and got a glorious 800x600 pixels image. The wonders of the
@ESP32net
/
#espressif
never ceases to amaze me. :-)
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The paperclip button cell battery holder for mounting the battery inside a PCB ( ) also works in a "normal" setting if modified a bit it just needs a little solder blob in the middle to get a good connection.
A post from
@rabid_inventor
reminded me of this project I did 10 years ago. It was kinda fun to put all thru-hole parts *inside* the PCB. The board almost got down to a SMD design in height. The paperclip CR2032 battery holder worked quite well.
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When I originally saw the title I was thinking "Ah!, a book with small snippets of tested&vetted schematics for modules. Maybe with a good layout for each as well." But this book is also simply amazing - I can't imagine the amount of time & research that was involved there.
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Can't have too many electronics books ;) And the TTL Databook in hardcover is always nice to flip thru when needed. $5 for the lot + $10 shipping is a steal.
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Last Friday also had this in a parcel for me. The very beautiful VQB71 displays. They do have an annoying footprint and are common anodes which always are somewhat of a annoyance. But the double segments and the extremely deep red color (not visible here) outweigh those issues.
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These seem very nice for hooking on test clips, probes and power to a PCB. If the translator is correct they're less than a dollar for 20 pcs. I have to find these locally in EU or AliExpress and get a few handfuls to be used in all my future projects.
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Books books books. You never can have too many electronics and programming books. Especially written by the late Don Lancaster. $25 for this lot is fairly decent....
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The "video card" for the no-MCU CHIP-8 system is starting to come together. Pixel data in the RAM on middle PCB is scanned and shifted out to the display autonomously. The Arduino at the right only updates the ram with new pixels.
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As an experiment I'll do a giveaway of 6 of my Font & Hole-sizer rulers. Reply to enter the drawing. Retweet to get four extra chances to win in the drawing. I randomly select the winners next Sunday at noon CET. I know it's a bit cheesy but free stuff is free stuff ;-)
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Is this SWTPC CT-82 terminal cool enough to be bought for $200? On one hand SWTPC is a classic brand, but it's not a ADM- or DEC- good looking ;) It's located really close to me so I don't have to fear shipping damages...
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Let's play the "Which part doesn't really belong on this PCB?"-game... I discovered that I didn't have any SMD 74HC30 8-input NAND gates available. So for the time being a patched-in DIP will have to suffice. :-)
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I didn't check the requirements of the flash for RP2040 so I bought a dozen of two types and hoped for the best. Neither worked. ;(
So I had to remove a tiny QFN/USON flash from a Pico board and patch it in onto the huge SO-8 footprint of my board. It worked. :)
#DaddyLongLegs
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I've now tallied up the 58 kilos of NOS 74-series ICs I bought. It ended up at 859 full tubes having 91 types. Lots of latches and transceivers, counters and a good selection of common gates. So I'm happy :) These are the ICs I found loose in the bottom of the two boxes...
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I haven't realised before that FFC cables and connectors are really cheap. I guess it's not a surprise considering how often they are used in modern tech. A 12 conductor 30cm (1ft) cable is 5 cents. The connectors are also 5 cents. I have to try to use some in a project soon.
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Today I felt a bit adventurous and went down to my local garden shop and got me a roll of copper tape so I could try the old technique of cutting pads of the tape and solder the components to them. This is a small mic amplifier for a a project using the Goertzel tone detection.
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This new DC-DC converter seems quite interesting for designs when you have spikes of high power demands and want to run from coin cells. I'm glad they didn't market it as having an AI algorithm. :-)
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I think I got lucky on this $10 grab bag with retro ICs. Three 8088 CPUs, two 8085 CPUs, a 8087 and a 80278 floating point co-processors, a few floppy disk controllers and some SRAM, and RAM/PIO combos. They will be put into to the " future projects" boxes as usual. ;-)
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The maximum length of the ribbon cable between a floppy controller and the drive is 20 ft = 6 meters. :shocked: That's like 10 times of what I would have expected - especially with the interface being just open collector and not totem pole.
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I soldered up one of my Kimchi PCBs. I'm quite happy with how it turned out. The patch wire is just to fix a broken track on the pcb. Runs when on external power, but my old low quality CR2032 sags too much. So I'll pop out and get me a par of quality batteries and test.
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By some reason the F(lip) command in the KiCad 3D-viewer really amuses me. I can sit there and just flip it while thinking of something.
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I've wanted this book for a while and I now actually ordered it. Could get it from my local Amazon for $184, from Amzn Germany for $55 shipping included or $34 from Amzn US with shipping & import taxes included. I opted for the latter but it's silly to ship across the world.
;-)
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Well, I'll be darned. You can actually buy fuses by the meter. ;-) I've been tinkering with electronics for decades and have never seen this before... Btw, if you're interested in troubleshooting/repairs of SMPS'es I can recommend
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Soooo.... what to do when you're out of kapton tape and you need to have a part of the board isolated? You go back to the techniques of the 70s when people used a drill to make breaks in the "long-stripes" Veroboards. Works just as well today for donuts boards. :-)
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Is it only me that gets this feeling when ordering? I never can remember if the usual numbers like 0805 and 0603 are in metric or imperial. Couldn't they have rounded the numbers slightly different to give them a unique name?
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The Toshiba data book looks like it's home made in the 70s. What's up with that monospaced font they're using? It looks really odd, but I kinda like it.
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I received my "Trace resistance and crosstalk"-test PCB that I'll later this week will do some very unscientific tests with. I also tested the silkscreen resolution and apparently I could have gone quite a bit smaller than 0.65mm and not stopped there. That's unexpectedly good!
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