Playable electronic modules - modules in action - Page 1
Forum section: electronics / projects

author: HendriXML
author_rank: Super Contributor
timestamp: March 03, 2019, 03:22:34 pm
content: Hi,I'm in the process of creating playable electronic modules for my son (9).For logic gate circuits I bought IC’s from the HD74LSXX series. The attached example will for instance be using a HD74LS86P. This should be somewhat ESD safe…I hopeThe circuits will be mounted in a 3D printed box, with a symbol sticker on top and the IC’s as a dead bug on the bottom with connections to the (5V) power rails with a 100nF capacitor and IN and OUT pins of the IC.The power rail can be daisy chained (?). I already made wires that split from 1 into 3 connectors. I’ve chosen for female connectors because they’re a bit safer (more isolated) to have them unconnected.The modules will be connected with 20 cm (silicone) wires. I don’t know if this is problematic.Before implementing this, I would like to know if I’m missing something..Feel free to comment!

author: HendriXML
author_rank: Super Contributor
timestamp: March 03, 2019, 07:37:36 pm
content: I created all of the IC sticker (vector)drawings.If someone is interested in those, let me know! The price per module is less than 1 euro all inclusive (my guess), so these toys will not become expensive. It will (probably) eventually evolve into stuff that can also drive Lego Technic.They match a 5x7cm perf board. I'll laserprint them on plastic stickerpaper (AliExpress). In combination with Visio that stuff is also great to transfer very accurate measurements/positions of objects.It is less sharp than printing on normal paper, but it can handle much more abuse.

author: ebclr
author_rank: Super Contributor
timestamp: March 03, 2019, 07:43:36 pm
content: Your sun will fell more fun on playing with thishttps://www.labcenter.com/

author: HendriXML
author_rank: Super Contributor
timestamp: March 03, 2019, 07:58:08 pm
content: Quote from: ebclr on March 03, 2019, 07:43:36 pmMaybe, but these kids to day do a lot of virtual activities. I'd like to encourage him to do also real world stuff, with real world problems (and problem shooting) and these modules are a small step towards to that.

author: OM222O
author_rank: Frequent Contributor
timestamp: March 03, 2019, 08:01:31 pm
content: one suggestion would be to use small perf boards which can be daisy chained together rather than using the "6 gates in one box" approach. if you have each gate on a separate, smaller board, the wiring for more complicated projects in the future will be a lot easier, but using a box approach your wiring will become a spaghetti monsteralso you can put LEDs both on the inputs and outputs so it's more obvious how each gate is behaving.

author: Gyro
author_rank: Super Contributor
timestamp: March 03, 2019, 08:08:59 pm
content: I remember back in the '80s one of the UK electronics magazines (I think it was Practical Electronics) gave away a sheet of DIP IC sized stickers that could be put on top of standard 74 series logic. They were small but readable, it seemed like a pretty good idea at the time.Of course they didn't provide enough stickers for each part - I can't remember if it was a commercial idea that never took off.You could maybe revive the idea though, to make it compatible with ICs on a breadboard rather than large modules.

author: HendriXML
author_rank: Super Contributor
timestamp: March 03, 2019, 09:02:28 pm
content: Quote from: OM222O on March 03, 2019, 08:01:31 pmI've made some early prototypes (with only transistors) and have seen what you say to be true. However not all gates need to be used, they're all exposed because they come free. One positive thing about larger modules is that they stay flat when making use of flexible silicone wires.However this whole "project" needs to evolve. It starts educational and probably ends more practical.

author: HendriXML
author_rank: Super Contributor
timestamp: March 03, 2019, 09:26:10 pm
content: Quote from: OM222O on March 03, 2019, 08:01:31 pmHad that in mind also, but that would need to be implemented in a very elegant way, otherwise it becomes a bit to intimidating. With the split wires one it is possible to lead a debugging one to a led on a other module. Debugging is a skill as well

author: HendriXML
author_rank: Super Contributor
timestamp: March 03, 2019, 09:26:51 pm
content: Quote from: Gyro on March 03, 2019, 08:08:59 pmThought of that tooThe current approach is certainly not space efficient.

author: HendriXML
author_rank: Super Contributor
timestamp: March 03, 2019, 10:50:10 pm
content: Made a schematic and PCB layout in KiCad, just not to get lost....Having done that, I think the module is a lot easier to wire

author: HendriXML
author_rank: Super Contributor
timestamp: March 04, 2019, 03:39:13 pm
content: I finalized the soldering of 1 module.First time using lead free solder.. (The toy is boxed, but better to be safe. Don't know whether the perfboard is lead free anyway. )I had to take care not to heat the plated holes to much. Had to clean solder once and then the plastic sticker locally melted. Besides that it went well, but it is very time consuming for something that supposed to be cheap.Only used 2 isolated wires. Most of the connections on the IC are made by creating a small wire loop at the end of an thin wire to keep the thicker wire and IC pin together and soldering those 3. Should make desoldering easier. But it is probably still a lot of work to replace the IC.Maybe on the next one I will do the IC first, then the sticker and finally the pinheaders.

author: HendriXML
author_rank: Super Contributor
timestamp: March 05, 2019, 01:19:29 am
content: The PCB is now mounted in a 3D printed box, it has inside 4 stands in the corners of 10mm: high enough for the dead bug not to get crushed.Had ordered some of those hex screws (AliE), I think they look great. They're not really needed because I had to squeeze the PCB in, but now I know it stays in.For complete DIY and the low cost I'm happy with the result.It is quite sturdy and relatively heavy.

author: HendriXML
author_rank: Super Contributor
timestamp: March 05, 2019, 11:02:23 am
content: While testing the module I found the inputs to be very sensitive when not connected.Can I leave them floated or is pulling them to ground with let’s say a 10k resistor “obligatory”?And what would be the highest resistor that is still functional? I choose a 10k because then the current loss is still doable when a lot of inputs are in use.

author: Gyro
author_rank: Super Contributor
timestamp: March 05, 2019, 11:36:38 am
content: Ah, that's something that one of us should have picked up on.Firstly, yes, floating inputs are bad on cmos logic. I think you could safely go up an order of magnitude to 100k on the resistors.That brings me to...1. Input protection - you may want to add protection diodes to each input for static protection. Maybe overkill, socketing the IC might be an easier solution.2. There are no VCC and Gnd pins on the box (aside from the PSU headers, which I assume you intend to daisy-chain). You are very likely to want to tie one or more inputs high or low when experimenting. You probably want to provide 4 pins of each.

author: OM222O
author_rank: Frequent Contributor
timestamp: March 05, 2019, 02:50:49 pm
content: Yes, as Gyro mentioned, either use TTL logic instead of CMOS (more power draw for more gates if floating inputs are a bigger issue)or tie them to ground with 100k (47k to be on the safe side) if random readings on floating inputs are a bigger issue. it comes down to how large the project is and how lazy you are. I would personally stick to TTL as it's unlikely for you to be using lets say 500 gates at a time? even ben eater (youtuber) made a full 8 bit breadboard computer using TTL series logic and the power draw wasn't too bad. that will also saves you cost of the resistors (although fairly cheap) as well as soldering them in one by one (my main point of laziness lol).

author: HendriXML
author_rank: Super Contributor
timestamp: March 05, 2019, 03:38:53 pm
content: I thought I bought the TTL logic stuff looking at this websitehttps://www.electronics-tutorials.ws/logic/logic_7.html.I also ordered CMOS IC’s with the same gates like the TC4030BP.On the introduction pagehttps://www.electronics-tutorials.ws/logic/logic_1.htmlit says on the LS series:74LSxx: Low Power Schottky TTL – Same as 74Sxx types but with increased internal resistances to improve power consumption. Supply voltage range: 4.75 to 5.25 voltsSo I’m a bit surprised with them beeing so sensitive.Did I buy old school stuff which is too “modern”?I’ll add the resistors. This however will make the modules even more time consuming.

author: HendriXML
author_rank: Super Contributor
timestamp: March 05, 2019, 03:49:23 pm
content: Quote from: Gyro on March 05, 2019, 11:36:38 amThat’s a good idea. Will add some boxes with just that, and proper symbols and all. I already have 1 module with dipswitches wich can give either high or low. A more user friendly module with larger buttons and toggle switched will follow.

author: Gyro
author_rank: Super Contributor
timestamp: March 05, 2019, 05:01:32 pm
content: Damn, I didn't notice from your OP that you were using bipolar 74LS series. In that case your 10k is about right, but pulledUPto 5V rather than down to GND. Bipolar LS TTL logic has very unequal high and low currents (Input : about 20uA high and 360uA low, Output: 400uAhigh and 8mAlow).It is much harder to pull an LS TTL input low with a resistor, you need to achieve no more than 0.8V with the 360uA input current flowing. If you pull up then you only need to get above 2.7V with 20uA flowing. If you try to use pull-down resistors then your other gates will have difficulty overcoming them with their relatively weak output high capability. Floating (unconnected) bipolar TTL inputs are an old trap, they float high on their own but are very sensitive to noise.In the same way, if you want to drive an LED from LS TTL, then you put it (and its current limiting resistor) between the output and +5V. This means that it lights on logic low.This may a get a bit confusing for a young mind (it made my head spin a bit just typing it!). I really suggest that you consider using CMOS 74HC logic instead. Its input current is symmetrical at <1uA (hence 100k resistor) and the outputs are also symmetrical at +/- 4mA. Itismore static sensitive, but not as much as modern low voltage CMOS. Its 2 - 6V VCC and very low supply current make it much more battery friendly too.Sorry for the confusion. I've linked a 74LS00 datasheet and 74HC00 datasheet for reference - they are representative of their respective logic family electrical parameters.http://ecelabs.njit.edu/student_resources/datas/74ls00.pdfhttp://pdf.datasheetcatalog.com/datasheet/on_semiconductor2/74HC00.PDF

author: HendriXML
author_rank: Super Contributor
timestamp: March 05, 2019, 05:51:28 pm
content: Thanks, you give a lot to think about. I’ll study the datasheet, but also do some measurements in pulling up/down.Having inputs which need to pulled down is probably also handy when using comparator modules.Battery life I’m not really concerned with yet, if some experiment is worth running for a long time it’s probably better to make a dedicated circuit for that using more optimal components. Otherwise the modules will be “in use” to much, increasing the need for more of them.

author: HendriXML
author_rank: Super Contributor
timestamp: March 05, 2019, 11:13:37 pm
content: Quote from: Gyro on March 05, 2019, 05:01:32 pmWhat you say is also explained in more detail herehttps://www.electronics-tutorials.ws/logic/pull-up-resistor.htmlfor those interested. The difference between pull up/down is so large, that I’m not going to measure voltage drops15k Pull up it will be!

author: HendriXML
author_rank: Super Contributor
timestamp: March 06, 2019, 12:42:50 am
content: The resistors are doing pull ups. I call them pull up resistors.Also added an extra cap, because the modules may get long power wires while chaining them.

author: radix
author_rank: Contributor
timestamp: March 06, 2019, 02:07:31 am
content: The toy looks interesting, but I keep having thoughts about something. Be careful that the modules aren't left lying on the floor. Stepping on one would hurt much much more than stepping on a lego.Maybe you should think about right angle headers...

author: HendriXML
author_rank: Super Contributor
timestamp: March 06, 2019, 09:12:16 am
content: Quote from: radix on March 06, 2019, 02:07:31 amThe modules know how to defend them selvesBut you’re absolutely right, stepping on Lego is unpleasant, stepping on those pinheaders would get bloody. Thanks for pointing that out. I envisioned the modules to be played with at the kitchen table, but that being obligatory is a real disadvantage.Angled headers would be much better in this regard, but are also more inconvenient. So I need to give this one more thought.

author: OM222O
author_rank: Frequent Contributor
timestamp: March 06, 2019, 11:32:09 am
content: Just a side note: you can get 10 PCBs for 2$ from jlcpcb (+ shipping which depends on what you choose). I think that will end up being more convinient and actually lower cost rather than using a perf board and wires to solder everything together. You can print and put the symbol of the gate on the top as well so the same pcb can be reused for all of the gates. It' also a lot easier if you want to add leds on the inputs/outputs.

author: HendriXML
author_rank: Super Contributor
timestamp: March 06, 2019, 11:45:02 am
content: I found a graceful solution.First the direction of the modules will change 90 deg (thus portrait). Inputs on the left, outputs on the right. This will give a better view on the sticker. (And follows a common design rule.)The headers will move to the edges. Where they are sided with a 3D printed wall (5mm thick).The powerheaders will also move, one on the topleft and on on the topright edge.Maybe I can make the modules click to each other with magnets, there would be room in the walls for that. However 3D printing holes in that direction is not very precise.

author: HendriXML
author_rank: Super Contributor
timestamp: March 06, 2019, 12:15:53 pm
content: Quote from: OM222O on March 06, 2019, 11:32:09 amI once got a PCB from Elecrow with a special offer 10 pcs of 100x100mm for 12€ including shipping. But that seems to be gone.https://www.allpcb.com/online_pcb_quote.html?hidLength=50&hidWidth=70&hidNum=10&countNumer=10&txtSelNum=&hidLayers=2&Thicknessquote=1.6With this manufacturer the shipping is free. Otherwise that will add up. Those perfboard where not expensive, but the time to create one gate module is near 4 hours now. Going with SMT and designed PCB’s sound attractive then. However I would need to buy new parts also (or bend the pins).

author: SpencerTC
author_rank: Contributor
timestamp: March 06, 2019, 02:02:30 pm
content: I like this idea. I volunteer to teach a beginners electronics class once a week and we haven't gotten to digital design yet. I think I will use your idea and make several for demonstration purposes, I will likely just give them breadboards and IC's when we get to the hands-on lab portion of that concept.Thanks for being my muse in this instance!

author: HendriXML
author_rank: Super Contributor
timestamp: March 06, 2019, 02:53:44 pm
content: Quote from: SpencerTC on March 06, 2019, 02:02:30 pmNice to hear!If you need files I could create a GitHub repo for this or post them here, but I have to update them all.This is what I gotStickers with symbols in Visio, great tool for parameterized 2D drawingsCase/box in FreeCad, great tool for parameterized 3D designsPCB layout in KiCadBut all of them are ready for a 2.0 revision.

author: Mortymore
author_rank: Frequent Contributor
timestamp: March 06, 2019, 03:03:26 pm
content: Some time ago I built some "Circuit Tiles" as I called, to teach something about electricity to my kids.Searched the internet for some games, but found nothing available in my country, so I build some stuff with the thing I had.Saw some games that had magnetic connections, some would clip, others had connections like puzzles...My option was to interconnect the modules with alligator clips, using crimping terminals with a nail inside to secure them to the wood base tiles.Since in your case, with a lot of connections to logic ports and such, I think an option could be use terminals like the Arduino boards has, and the connections would be made with jumper wires (like those used for breadboards).EDIT: Why invert the type of connection you showed? Because you can even use simple wires with the insulation striped on the tips to make the connections, in case you run out of jumpers. And you could dedicate to each port, not just one interconnection pin/plug, but 2 or 3, since you may have to interconnect them with other inputs/outputs.Leave you with just some ideas...I'm curious about your work, because I might be interested to move from electricity tiles, to electronic tiles. So your findings and options, may be useful to me.

author: HendriXML
author_rank: Super Contributor
timestamp: March 06, 2019, 04:36:15 pm
content: Quote from: Mortymore on March 06, 2019, 03:03:26 pmNice work!The reasons I choose male pinheaders is because:With the counterpart - the females it is harder to create shortcircuits, so no problem to have them hanging around.I couldn't find any other silicone prepared wires: it needs to be flexible, otherwise the modules don't keep their location/alignmentWires are of high quality but also cheap, so its easy to have enough of themThe pins on the PCB are very durable and strong, male connectors can easily breakThe pins are a self defence mechanism, so no one steps on the modules that took so much time to createIt is always possible to cut one end and put a male one on them.When it's time to interact with an Arduino I might make headers with stickers on them. Haven't thought about it yet. All the gate modules will probably become redundant by then (I guess).First I will also have to create modules with comparators, oscillators, etc.Switches, potmeters, LDR's will probably just be wired with Dupont connectors.

author: HendriXML
author_rank: Super Contributor
timestamp: March 06, 2019, 09:26:58 pm
content: The idea of putting magnets on the sides will be implemented in the upcoming revision. Having modules clicked/close to one other saves desktop space and make it much easier to transport a setup. Pins and wires won’t be under tension as much.In Cura the software that renders the 3D print I found a way to create a local solid fill. I will just dril holes in those solid fills and glue the cylindrical magnets in them. Will off course make a drilling template to have the magnets allign precisely. The local solid fills are also important for the PCB stands.

author: SpencerTC
author_rank: Contributor
timestamp: March 07, 2019, 09:12:41 pm
content: Quote from: HendriXML on March 06, 2019, 02:53:44 pmThank you!Honestly, the only resource (other than the idea) that I would use would more than likely be the stickers. I do believe others might also want to use this idea, so a repo with all relevant information would be nice.I thought of a potential feature....the labels could be removable (magnet, velcro, etc...) that way you could make an array of gates, put some known inputs in and have a few LED's scattered throughout the design for outputs...then you could make the students decipher what type of gate each of them are.

author: HendriXML
author_rank: Super Contributor
timestamp: March 08, 2019, 01:07:34 am
content: I recreated the gate stickers, they now in portrait stand. This allow a better view on the symbols. The power connectors do not block the view as well.I've one rev 2.0 case done, it takes 3,5 hours to print. Estimate all incl. cost was about 0.80 €.The measured weight was 29 gr. Which corresponds to about 0.60 € worth of PLA.I'm still struggling with how to mount the magnets. The coating on them makes them hard to glue, but it can be done with superglue they say (degrease, fine grain sanding). However that is of a later concern.The new case has more margin so the PCB/case is not under any tension anymore. The hex screws can be tightened a lot, I'm pleased with that choice.Next step is to resolder the XOR example and give it a new sticker. The headers will be soldered after applying the sticker. I don't want any burn-marks any more.

author: HendriXML
author_rank: Super Contributor
timestamp: March 08, 2019, 01:17:13 am
content: Quote from: SpencerTC on March 07, 2019, 09:12:41 pmNice idea! (They could also be covered.)I'll be creating nice assignments as well. I guess it will be in the form of:John wants his lights (use LED) to go on when it gets dark (use LDR). But only when he's at home (use switch 01).

author: HendriXML
author_rank: Super Contributor
timestamp: March 08, 2019, 10:20:20 am
content: Quote from: SpencerTC on March 07, 2019, 09:12:41 pmNo problemIf anyone needs something I’d like to hear it.Creating a repository takes a lot of effort to do it right, so from an efficiency point of view I’ll delay that if possible or let the idea go. I’ve put a poll to this thread, to measure the interest in a repo.The stickers match the 5x7 perfboards, so Visio would be needed if changes are required.

author: Gyro
author_rank: Super Contributor
timestamp: March 08, 2019, 11:25:00 am
content: Quote from: HendriXML on March 08, 2019, 01:07:34 amYou've forgotten to include (multiple) VCC and GND pins for tying inputs high or low.P.S. You could also do with adding a multiple LED block for easy monitoring of output states. If still using LS TTL then I suggest driving them with a 74LS04 inverter so that the LEDs light for logic High.P.P.S. If you provide multiple pins for each output, then it would be much easier to connect multiple jumpers for combinatorial logic. With single pins and female jumpers it's going to be very hard to, say, connect one output to more than one input.

author: HendriXML
author_rank: Super Contributor
timestamp: March 08, 2019, 01:10:32 pm
content: Quote from: Gyro on March 08, 2019, 11:25:00 amI think that is still a good idea, but my goal is at first to have the modules (visually) as simple as possible.With almost no possibility to connect things the wrong way. (The pins are now also protected by a wall, so there’s almost no room to add extra’s without compressing the layout)The highs and lows could in the current setup come from another module. I’m thinking about giving the inverter module a double function. Which with no input connected would output a low. And having a 2 pin connector at the input side, one as the inverter input, one a ground pin. So it would be possible to either use or jumper or a switch on a wire to create a high output, or use an active input.That solution is not really short circuit safe. So I’m still thinking on it. (It should visually also be easy to understand).For one output to many input relations I’ve made splitter wires. (1 to 3) These are easy to make from 2 normal ones and thus also cheap.

author: HendriXML
author_rank: Super Contributor
timestamp: March 08, 2019, 09:43:12 pm
content: I recreated the stickers.I went for the KiCad color scheme. (Have to check if it prints ok on sticker paper).I altered the inverter module to have its dual function. The ground symbol is made extra meaningfull, it is even more like a down arrow making the input low. So that will be easy to remember.The output of this module will get LED's as Gyro suggested. The reason only this module will get output LEDs is mostly costs (time!). But also the importance of using encouraging to use other debug methods ifneeded. If there's always a very easy way to check a portion of the schematic, it's only human that the thinking goes down and the guessing goes up.

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 10:41:20 am
content: One way to have a perfect fitting sticker is to use the pins to align the sticker with the PCB. But also start with a larger sticker and cut (with the sticker downwards) using the PCB as a ruler.

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 01:57:44 pm
content: So the inverter modules will get a ground pin. It is however possible that an output of another module is accidentally connected to that pin. I’ve read that a gate IC can have one output short circuited for only one second. But also because it is almost impossible to replace them I want the best chances of surviving a short circuit.So I thought is would be better to have a 100 ohm resistor between the “groundpin” and ground. With a pullup resistor of 15k that would be small enough to get a low signal when using a switch or jumper.Are there alternatives (besides moving the resistor to the outputs)? There’s very little room left on the PCB.My initial thought was just to replace the IC. But the turned pins I got to make that easy are just to loose around the IC legs. The IC would simply fall out with a good shake. I probably ordered LQ ones (aliex).

author: nctnico
author_rank: Super Contributor
timestamp: March 09, 2019, 02:15:55 pm
content: Why not make one large board with IC sockets and header connectors for each pin? This saves a lot of tedious soldering.Decades ago I made this:This has been great for learning logic circuits. It has a 5V power supply, LEDs, switches, transistors, two oscillators and some sockets to put discrete parts in. One thing I'd do differently is to have two or three headers per pin so I don't need daisy chain wires. This board was hand drawn using a velt pen BTW. I had to cut it into two pieces because the entire board wouldn't fit in my etch bath.

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 02:40:22 pm
content: I really like the idea of just exposing a socket, and make multi purpose modules. Not having to solder on the bottom side would save a lot of time too.But for this educational beginners project I started with a very narow focus on just connecting Outs and Ins. As skills progress it may get more complicated in usage. For example finding out what pins do what on a IC.For children it requires different properties than just beeing functional. Smaller modules are probably more “playable”. I’m no expert here, but I’m exploring the possibilities hoping the choices I make will turn out ok. (Making stuff for myself is easier)

author: nctnico
author_rank: Super Contributor
timestamp: March 09, 2019, 03:06:49 pm
content: If you are going to make modules then I'd put TVS diodes across all the pins and use sockets. Zapping a chip due to ESD is done quickly.

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 05:59:10 pm
content: Quote from: nctnico on March 09, 2019, 03:06:49 pmMy hope is that TTL logic and pullup resistors of 15k at the inputs are enough to tackle the ESD zapping.Didn’t know of TVS diodes, so thanks!Having replaceable IC’s is probably the easiest solution. The IC’s are relatively cheap and not hard to check for proper working. To bad the turned pin arrays are to loose.

author: Gyro
author_rank: Super Contributor
timestamp: March 09, 2019, 06:54:18 pm
content: Quote from: HendriXML on March 08, 2019, 09:43:12 pmIt will still be a bit of a mental leap (especially for a young mind) to understand that a lit LED actually signifies a low on the output of the inverter and hence a high on theinput. You could include a 'hidden' inverter to ensure that a lit LED indicates a high output state with less effort than a separate 'display' module.Edit: Alternatively, if you did do a separate indicator module, then you could drive the LEDs with a simple common emitter transistor stage with high enough input resistance to give a 'true' indication, even with the weak source capability of 74LSxx.Without wishing to harp on about logic families again... Regarding the logic family. If you were to use 74HC CMOS, then you could introduce a fair amount of ESD protection by employing the internal protection diodes already within the ICs in combination with a series resistor. The protection diodes are normally good for 5mA continuous (higher in ESD pulse), so with, say, 100k series resistors, you would get a reasonable level of protection (in fact the threshold might become the insulation breakdown voltage of the resistor). In normal high speed circuits, such high value resistors would cause unacceptable slowdown, but not for a 'static' trainer.

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 07:23:26 pm
content: This picture show why the turned pins I received are worthless! Some have internal connections some don't. This could have been horrible in an serious application of these pin headers!

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 08:08:34 pm
content: Quote from: Gyro on March 09, 2019, 06:54:18 pmThe led corresponds to the state of the switch though. But you may well be right, it is something I’m not sure about. It will be the next module I’ll implement. Inverting is a simple operation, but a difficult one for the brain. If it’s to hard to grasp I will split the dual function module into seperate onces. And keep the difficult one for later.I previously made a LED output module (old style: components on top, will be recreated). I think it works with 2N7000’s, that one “should” be used to show outputs.

author: nctnico
author_rank: Super Contributor
timestamp: March 09, 2019, 08:19:24 pm
content: Quote from: HendriXML on March 09, 2019, 07:23:26 pmBetter buy good ones then. Get real ones from (for example) Samtec.

author: Nusa
author_rank: Super Contributor
timestamp: March 09, 2019, 08:58:10 pm
content: If you've got white space on the label, put something useful on it. Such as the truth table for the operation. Or perhaps the alternate representation for the same gate. (e.g. a NAND gate is the same thing as an OR gate with inverted inputs)

author: Gyro
author_rank: Super Contributor
timestamp: March 09, 2019, 09:07:16 pm
content: Quote from: HendriXML on March 09, 2019, 08:08:34 pmYes sure, the LED will follow the state of the inverter input, just not the output (I guess it depends where you position them as to how much sense it makes). If you are trying to save work (and are doing PCBs) then maybe you can use the same one, populated with either output pins or LEDs + resistors. Then you could simply use different labels - Inverter module for one, display module for the other.Still soldering effort but less than two different designs. Just a thought.P.S. Those sockets areterrible, I trust you're not going to pay for them! You don't really need the cost of turned pin sockets for a project like this - locally sourced flat spring contact ones will be fine. Easier to swap the ICs too (proper turned pin sockets hold on very tight!).

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 10:14:25 pm
content: Did some poking on 20x40 pins, thus 8000to check how many where useless, against how many are just LQ. About 35 pins where without contacts.They where 3,30 € in total. Don’t know how much the HQ ones should cost, but I will check them out.I’m thinking of buying less AliExpress stuff. But with Mouser it can sometimes be a bit overwhelming how many there’s to choose from. And not only that, one needs to spend 50€ at once to get free shipment. That’s not to hard, but then to forget a part is unpleasant. So I keep delaying ordering stuff over there.However having to wait a month on crap turned pins is not pleasant either.20 years ago local electronic part stores where quite common in the Netherlands, but now only larger cities have them. For me not handy.

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 10:27:18 pm
content: Quote from: Gyro on March 09, 2019, 09:07:16 pmI wasn’t clear on that one. The inverter will probably drive a 2N7000 to drive the led. Thus it should follow the output. I wouldn’t like to loose 10mA of driving capacity of the inverter.

author: HendriXML
author_rank: Super Contributor
timestamp: March 09, 2019, 10:58:15 pm
content: Quote from: Nusa on March 09, 2019, 08:58:10 pmI’ve been thinking about that to, it’s hard to resist. But having a truth table always in view, might delay the growth of operational knowledge.I will exploit the power of the printed stickers later on!For adults it easy to use abstract symbols, for kids that is something they need develop.In the (playfull) assignments / puzzles I’ll put a few in that are about combing gates to create elementary ones. Comming to the conclusion that multiple NAND’s (with use of GND) can be used create all others.

author: Mortymore
author_rank: Frequent Contributor
timestamp: March 10, 2019, 10:25:48 am
content: Let me add another of my 2centsDon't loose focus.There's been a lot of interesting input given here, but if your "contraption" is intended for kids, keep it simple.Adding to much information or a big board... may be overwhelming for kids (starters) and demotivating.Keep your tiles simple. But, adding to that I suggest that you write a small book with simple instructions and experiments, with schematics, some introduction to functions. On some, instigate the curiosity proposing alternate ways to achieve the same results, or add a slight complexity to it, for instance, making a mix with 2 previous experiences or something.The building blocks should be simple and easy to read and understand, because that will be easier to visual memory, to build the circuit and to debug if necessary.The extra information should be provided in the book, and increased as necessary.Keep up the good work

author: HendriXML
author_rank: Super Contributor
timestamp: March 10, 2019, 11:53:39 am
content: Thanks,I’m weighing every option carefully, so any feedback is fine.For instance I won’t make the dual function module but split it. The modules are not short circuit safe, so having a ground next to an input is to risky. Having to warn for it will influence the friendliness perception of the modules.Will also check the effect of having (subtle) visual information on the connection type will do.Stuff to think about would be:input or outputdigital or analogactive, passive, powerThe reason for this is to lessen the risk of invalid connections when non digital modules arise. (Or connecting two outputs together)Will also use the LQ pinheaders. Thus no more deadbug style, but normal bottom PCB soldering, but without leads/pins sticking through. Will add some foam to the top of the IC to have some upward pressure from the enclosure bottom.It is always nice to target pro level results, but it can also mean the costs will rise too much.

author: HendriXML
author_rank: Super Contributor
timestamp: March 10, 2019, 01:24:48 pm
content: Did some checking but even simple connection suggestions are an abstraction. Color coding of the module traces could work, but has disadvantages. Having dashed lines looks alright but dashed lines should be used for other purposes.The best option IMO would be to use different colors of pinheaders just to show whether the input is digital, analog or passive. The plastic part of the pin header can be replaced without soldering so that can even be done afterwards. But for now I leave it as it is: digital is black

author: HendriXML
author_rank: Super Contributor
timestamp: March 10, 2019, 02:43:31 pm
content: Maybe I use this indication (XOR gate example) that the signals are digital.

author: HendriXML
author_rank: Super Contributor
timestamp: March 10, 2019, 04:29:51 pm
content: I think Lego lost the patent cases on their brick format. Otherwise I don’t think you even can be sued for making personal stuff. Mass producing is a different story. Or using their logo.I guess it even is ok to repaint a Rembrandt, just don’t sell it as a Rembrandt one.So DIY stuff seems ok to me.

author: nctnico
author_rank: Super Contributor
timestamp: March 10, 2019, 05:42:46 pm
content: In the Netherlands you can buy these brick-like electronics / electricity experimenting sets called 'Spektro':

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 10, 2019, 06:11:49 pm
content: Yes, there are plenty of electronics kits out there. (We call those ones Snap-Circuits here by Elenco). There's also tons of "springboard" kits out there, some of which include breadboards and even one with a microprocessor. There's also one's with magnets, ones with clip together modules, and all kinds of stuff.There is a website with a list of every electronics building toy ever made, but I'll have to find it. (NOTE: IDK how many of them will still be in production).HERE:http://www.zpag.net/Electroniques/Kit/Electronic_Kit.htm

author: nctnico
author_rank: Super Contributor
timestamp: March 10, 2019, 09:23:10 pm
content: Not all. I'm missing the kits from Philips (which I still have -I think-) on the list.

author: HendriXML
author_rank: Super Contributor
timestamp: March 10, 2019, 09:26:57 pm
content: Quote from: nctnico on March 10, 2019, 09:23:10 pmI think I had the B-variant. 2 transistors!!

author: HendriXML
author_rank: Super Contributor
timestamp: March 10, 2019, 09:28:58 pm
content: New version of the stickers. With the low/high level module.If there's enough room there will be a LED in each high rectangle.

author: nctnico
author_rank: Super Contributor
timestamp: March 10, 2019, 09:29:31 pm
content: Quote from: HendriXML on March 10, 2019, 09:26:57 pmI used to have the full set (until D IIRC) but I'm not sure whether I took everything with me when I moved out of my parent's house.

author: HendriXML
author_rank: Super Contributor
timestamp: March 10, 2019, 09:35:44 pm
content: Quote from: nctnico on March 10, 2019, 09:29:31 pmThat was a really well thought out system, with the schematics under the spring contacts and all. Even with that I found it quite challenging.

author: nctnico
author_rank: Super Contributor
timestamp: March 10, 2019, 09:41:11 pm
content: I ended up making my own modules for it.

author: HendriXML
author_rank: Super Contributor
timestamp: March 10, 2019, 11:04:33 pm
content: Quote from: nctnico on March 10, 2019, 09:41:11 pmFound a site with some of those kits. I can’t really find the one I had.http://www.sjelab.nl/sjelab.htmhttp://www.rrd.demon.nl/Philips%20experimenteerdozen/Philips%20experimenteerdozen.htmIt think my one box was a bit limiting. But that makes it also easy to create stuff with more possibilities for my offspringWhile doing a quick comparison, I think Phillips kits where more component based, instead of module based. But in the end to what extend things can be combined does matter. With modules that could be less. (I’ll throw in a Arduino then) Interacting with Lego to make mechatronic projects is important for long term playability. Thus that is one of the goals I’ll keep in mind.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 12, 2019, 03:01:35 pm
content: Lego already has two robotics kits available.

author: HendriXML
author_rank: Super Contributor
timestamp: March 12, 2019, 04:38:12 pm
content: Quote from: Cyberdragon on March 12, 2019, 03:01:35 pmI know, and they’re nice but not cheap. DIY can go well beyond of what they’re offering. Certainly not because it’s better, but because it does not need to be as good. With personal use, one can get away with “ugly” solutions. I tend to make a lot and different kinds of them if it becomes a success.

author: HendriXML
author_rank: Super Contributor
timestamp: March 12, 2019, 07:41:49 pm
content: The high/low module will be controlled with 2 types of switches. One push button and one toggle switch, wired to a female Dupont connector as shown on the photo.I measured the bouncing (MeasureA) to get an idea. Then I tested with a 100nF capacitor RC circuit (MeasureB). Because this still showed bouncing, so I went to 1uF, the next one I had on stock.The graphs are shown. Instead of a normal inverter, the switches will drive a Schmitt-trigger inverter (SN74HC14).Later on I will do some testing with the SN74HC14 to see how much the delays will be in practice.

author: HendriXML
author_rank: Super Contributor
timestamp: March 12, 2019, 08:15:23 pm
content: The full schematic is below. This is not complex, but still quite a task to realise it on a 5x7cm perf board.

author: Nusa
author_rank: Super Contributor
timestamp: March 13, 2019, 12:35:02 am
content: From the cost and space point of view, you could replace all of that with a microcontroller that software debounced the inputs, and gave stable logic outputs and lamp outputs. It also means you could implement timed pulse generator outputs trivially, if you want them.From the teaching point of view, you could use S-R flip-flops to debounce instead, using either SPDT switches or two SPST buttons (one for set, one for reset). You could show the logic involved on the label, either as a flip-flop box or equivalent logic using gates.

author: HendriXML
author_rank: Super Contributor
timestamp: March 13, 2019, 01:47:05 am
content: Quote from: Nusa on March 13, 2019, 12:35:02 amThanks, S-R flip-flops will certainly exposed as a module as well. That’s is also one benefit of making these modules for my son, I’m familiarizing with the components myself as well. I’ve the components “on stock” so there’s not really (much) added costs. But space might be an issue, all the stuff needs to be compact in x/y direction but also z.I’ve thought about showing the internal logic. Hence the previous idea of making a dual function module. (Switch/not gate). But this is one of the modules where it al starts, so I keep this one simple.I haven’t dived in the way software debouncing works, but I prefer this module to be reliable. If this module for instance drives a counter, it would be crap if it added 4 at a time.

author: amy
author_rank: Newbie
timestamp: March 13, 2019, 10:12:36 am
content: I'd d like to know what this module is designed for.How do children play?You're amazing.No one is going to make me a video game by hand.Look forward to seeing the full work in the future

author: HendriXML
author_rank: Super Contributor
timestamp: March 13, 2019, 12:08:35 pm
content: Quote from: amy on March 13, 2019, 10:12:36 am

author: HendriXML
author_rank: Super Contributor
timestamp: March 13, 2019, 12:22:16 pm
content: Did some testing with the SN74HC14 on a breadboard.Going to the ON state is delayed by 15 ms, going to the OFF state with some 25 ms.I did same rapid pushes on the button to see if everything was registered, and it was.So for human/kid interaction this is fast enough. For automated systems it might depend, but in that case better switches and the proposed latching method might be a good idea. My pushbuttons are probably of the worst kind: leaving the speed of closing/opening the switch up to the user. Better switches will be of the click/clack kind. Where some tension is build up and then released going into a different state much faster (like the toggle switch). Also better contact materials (gold) will give better results, but were on a budget

author: HendriXML
author_rank: Super Contributor
timestamp: March 16, 2019, 02:56:22 pm
content: Two of the new revision modules are ready!

author: HendriXML
author_rank: Super Contributor
timestamp: March 16, 2019, 03:01:11 pm
content: Surface mounting the IC's "my way", takes to much time so, I'll will order some of these. It makes the modules 50% more expensive, but I think it will be well worth it.