Jump to content


New Members
  • Content Count

  • Joined

  • Last visited

Everything posted by retro_doog

  1. No interest on these? I forgot to add these shells are all from New Old Stock carts that had the board pulled out. Actually a handful still have the cart board inside(usually the undesirable titles like Personal Real Estate)... If there are any takers, feel free to make an offer on the lot of them!
  2. Just an update, these have all been sold and shipped. Thanks to all who showed interest!
  3. Bought these several years ago when I was planning my own Multi-Cart. Now.... well there are enough capable multicarts out there. I suppose with a little dremeling one could use these shells for the custom carts on the market? I've got 30 of these. Prefer to sell all at once. The less you buy the higher cost per shell. Make a pre-shipping offer and let me know your zip code. Shipping's not free, ya know! I'm not Amazon
  4. Looks like I have roughly all of these sold. Just need to order parts and assemble/kit them up. I'm not likely to build any more single units myself, but I may be willing to sell batches of minimum Qty 10 bare PCBs to others who want to assemble and sell these. The cost would be the actual PCB Cost plus a small per board royalty. A sort of "pseudo-license" if anyone is interested...
  5. Looks like there's enough interest to order parts to kit and/or assemble these. After considering the BOM cost and time spent assembling/packing/shipping, I'm going to be at $20 + Shipping for a solder it yourself kit or $40 for a fully assembled board. If there's more demand than for just the 4+1 I have currently, I suppose I could order more PCB blanks. I'm also OK will selling PCB blanks in multiples of ten if others want to assemble and sell these.
  6. I made a PCB to allow me to probe a TI-99 Cartridge in action. It's basically a pass-though with some logic analyzer probe pods with the Address, Data, and Control lines organized nicely. I have one assembled unit and four bare PCBs. Not sure whether to sell assembled, as solder yourself "kits", or just the bare PCB. If there's any interest in these PM me and we can work out the details. I'm limiting this to US buyers with PayPal accounts. That way there is a record of transaction and a way for me to confirm postage and tracking as a way to protect both buyer and seller. Thanks for looking!
  7. The video link doesn't seem to work for me. I'm guessing this is the ST:TNG Scotty and LaForge scene?
  8. I was be facetious in my post Actually, you'll want to read my first post for my opinion of anything large and brick-like for the first stage supply. The entire point of my project is to replace the large, heavy floor brick with something more like one of these: https://www.digikey.com/products/en/power-supplies-external-internal-off-board/ac-dc-desktop-wall-adapters/130?FV=57|318132%2C57|318134%2C57|318137%2C57|318143%2C57|318171%2C57|318172%2C57|318173%2C57|318175%2C57|318178%2C57|318180%2C57|318182%2C57|318183%2C57|318185%2C57|318187%2C57|318191%2C57|318193%2C57|447538%2C57|447539%2C1371|379518%2C1989|0%2Cmu10W|2187|0%2Cmu30W|2187|1%2C-8|130%2C48|103542%2C48|116509%2C48|234830%2C48|235004%2C48|270755%2C48|305478%2C48|74515%2C48|87718%2C48|89177&quantity=0&ColumnSort=1000011&page=1&stock=1&k=ac+adapter&pageSize=25&pkeyword=ac+adapter You can get up to 24W in quite a small wall mount package! The internal supply I'm designing accommodates these compact external supplies in two ways: 1. The internal supplies are now all DC/DC not Low voltage AC to DC like the original. 2. The internal supplies are substantially more efficient, thereby further reducing the wattage requirement, and thus the size and cost, of the external supply. Also, in the world of power supplies, the simplest design(Transformer+cap, for instance) are usually the least efficient. For example, I've read that the ferroresonant XFMR is actually very inefficient at low loads. Take your Bench Supply, for example. Does it not get quite warm/hot? If so, that is all wasted energy not being presented to the output. Also, the "buzzing" noise you hear from transformers is also wasted energy. Electricity being converted into mechanical energy + heat. Modern semiconductor controllers can adapt to the load ensuring high efficiency across a range of loads. Not terribly important for our TI consoles, but super important in modern machines. Did you know that the core typically 1.0V power supply for, say, an intel processor running at a few GHz will draw a maximum of 50 Amps or more? And yet, it has many power modes that draw dramatically different amounts of power, so the current draw is actually violently "trashing". Imagine the power supply that has to handle that! And yet, it can be implemented in a couple square inches of PCB space and run quite efficiently across the wide range of load currents. Despite the older, higher voltage, technology in our TI Consoles, the power requirement is quite low. A bit less than 10W, I'd say. The semiconductor supplies I'm designing in will be small, cool, and efficient. When you get a look at the finished product, you may have a hard time believing it is not only powerful enough to run the machine, but will actually have about 150-200% of the potential capacity of the original, especially if you're used to looking at old hardware. 😎 It's a bit early for testing, but thanks for the offer I'll probably be recruiting a handful of beta testers to help out. They'll have to do a little work for me though, like measuring under different loads etc. I'll probably want people with specific external equipment to help me test like the TiPi, RF-Modulator, and so forth. I just have a console and a Speech Synth myself...
  9. Ah, of course! I'm designing in a 300-400mA capable 12V boost supply, so that should leave plenty of additional capacity for an external regulator. I just don't have one on hand to actually measure the exact amount of additional current needed, but I suspect it is only 50-100mA...
  10. I... Don't know quite what to do with that. Looks like a Bench test supply, which are designed with a lot of extra features to ensure the supply isn't damaged when testing faults on the unit under test(ie destructive testing). I'm sure a smaller, solid state version with the same features exists. Of course that is an AC power supply. I'm designing a modern DC to DC supply board that fits inside console. There will still be an external off the shelf AC/DC supply used, but the choices now are much smaller for equivalent power as they use semiconductor switching instead of large wire-wound transformers.
  11. I'll be using modern switching controllers complete with internal protection circuits. These things work with very small inductors as they operate at very high frequencies. The -5V inverting switcher is something like 2Mhz. I believe the boost regulator is 500KHz. Trust me, electronics in the power supply is a better solution than wirewound/heavy core transformers. We're only talking about a few hundred milliamps for the boost regulator. Most of these modern switchers are stable with ceramic filter caps as well due to the high switching frequency. You'll be surprised at how compact these modern supplies will be. The main variable for me will be how much Bulk capacitance to put on the board. I'll probably have pads for an overkill number of caps and only stuff a few of them in the final shipping supply. Just for reference, here's a 500mA 5V switching supply from one of my designs. The footprint of this circuit is roughly 0.75" x 0.5" (as referenced by the 0.1" headers the circuit is tucked between).That Common Cathode diode in the upper right corner isn't even officially part of the switcher. It's just a "diode OR" of two possible input connectors.
  12. Close, but I'd use surface mount flash and SRAM. No need for those huge DIP packages. Also I'd bring more of the PI-Zero down to the carrier board and put an Enet connector and possibly other useful stuff on the main carrier board(HDMI? Haven't checked to see what all the Pi-Zero makes available on the header connector). Also, more pins will make for a more stable Pi-Zero mounting. I'd probably also have standoffs to the Zero so you can "bolt it down". Alternatively, It could incorporate a DIMM connector for an R-PI Compute module as people seem to complain about the Zero's slow-ness. All Moot points as it appears there is no real market left and its unlikely people will want to keep buying the same thing over. And I need to stick to the small subset of things I actually want for my own machines so I can move on to that "next big thing" I alluded to above
  13. So I just watched a video on the TiPi and thought "That's pretty cool. Don't know if I'd actually use it once the novelty wears off. But, what a mess of wires, stacked boards, external power adapters!" I feel like I could probably make a single board that combines the 32K sidecar, TiPi with whatever R-Pi zero "hat" circuitry is needed, and just has the Pi-Zero plug into it. So a single board that you just pop the Pi-Zero module onto and put it in a nice case. Also, with my new supply everything would just be powered when you switch the TI on. Of course I'm assuming the hardware and firmware of the TiPi adapter board is "open" and freely available. I could probably even make a high performance version that you pop that DIMM looking R-Pi "compute" module onto. Of course I'd change all of those large DIP components into much more compact, but not impossible to hand solder SOICs and possibly have components on both sides of the PCB. Still... I'm not saying I'm going to make this, but I'm not saying I wont Is this a thing that people(enough people) would want? Or is the existing, possibly saturated market for TiPi users already content with the current solution?
  14. Looks like I figured out how to allow for lower than 12V input adapters without increased cost or complexity... My original parameters for the 12V was an input voltage range from +6V to +18V. This was suggesting Step-Up/Step-Down combo regulators which are complex and expensive. They also typically have low efficiencies in the 75% to 80% range(still better than the old linears, I'm sure, but...) Then I realized the way to make 12V is actually from my plentiful 5V switcher which is 90+% efficient! Also, a 5V to 12V 400mA boost regulator will be 86%-90% efficient depending on which IC controller I use(for about 20% more BOM cost, I can get the more efficient design). The cascade of near 90% efficiencies is pretty close to the lesser efficiency of the Step-up-down design, but much simpler and lower cost. In practice the combined efficiency of the 12V rail should be around 86% assuming there's not going to be much current drawn from it and no new hardware save oddball stuff that one might plug into the video connector is likely to increase the load by much, if anything. Normally, If I thought I needed a very clean +12V, I'd boost to, say 13.5V, and then put an low dropout, ultra low noise, linear regulator to 12V from that. However, it looks like the +12 is largely being used by fairly noisy digital circuits anyway(The CPU and RAM), so I suspect as long as I design for low current ripple(reasonable output capacitance should cover this), the 12V rail will be happy. Usually a rail like this is used in Audio/Video circuits for OpAmp bias and the like, but it appears that the bulk of the AV circuits use a balanced +/-5V dual supply, and the console creates filtered copies of those rails for the analog "branches" of the console circuitry. Again, I just need to cover current ripple since the 5V rail in particular is subject to constant switching loads(albeit at much lower frequencies than modern computers ned to handle). Again, a reasonable amount of bulk capacitance should handle the 3.6MHz switching transients... So, I've chosen the final candidates for all three rails and, thanks to TI's handy "WebBench" tool, I have the reference schematics for designs that should "just work" the first time as well! I may need to tweak the WebBench designs as they sometimes call out inductors that are not commonly stocked at DigiKey or Mouser, but that's usually not too big of a deal. I'm still a bit busy with other things, but I suspect once I get started, the schematic will only take a couple of hours and the layout should go fast as well. I'll just need to find a free weekend day to get this thing knocked out. Also, I want to get some reference measurements on my other two related projects to ensure I can reuse these designs on those as well.
  15. Yeah... I gotta say this all seems a bit too niche for the additional effort. Unswitched power for a trickle converter to turn on the main power is one thing, but unswitched charging power means there would be twice as many high power 5V regulators on board. For switched power to an external Pi-Zero, I'll be providing extra capacity to the side port. I'm not sure what interface adapter is used for TIPI, but again, perhaps someone will do a design rev to allow the option to draw from the console(either with a jumper, or by "Diode-ORing" with low Vfwd Schottkys). As far as the next big thing? I'm working on my version of that. Hint it's not an interface or peripheral designed for vintage computers, but I think it will appeal to a lot of vintage aficionados. That's all I'm gonna say about that at the moment.
  16. Well, I have several personal goals that this method defies: • A 5-pin DIN Male Plug Shell is slightly bigger than the rectangular opening in the back for power, so the receptacle would either need to "poke out" of the back of the unit, or you's have to do some filing to enlarge the opening. I say "Yuck!" to both • The board for the switch or switch relay would need to be about as large as the original supply board due to the mounting screw spacing, and the fact the on Beige units, only two screws are affixed and two bosses hold the board somewhat stable in order to make sure the internal power switch does not become decoupled from the enclosure switch actuator. (Still need to look inside my Black and Stainless model to see if it does the right thing and just uses all four screws. • The Meanwell power supply appears to be $28 by itself. 3+ Pole switches start to get considerably more expensive than single or dual pole equivalents, and theres no guarantee that there exists a 3-pole that physically fits and mates with the enclosure sliders. Relays are expensive as well. Now, at my low volumes, my solution will probably cost more than the combination of meanwell supply and hacked together or proto-board internal switch solution, but... It will truly look like it was made for the console, albeit looking more modern than anything else in the box. I may offer bare boards for those who want to order the parts from DigiKey and solder their own, I guess. I'd like to see what the final cost and demand are first. • The Meanwell solution is still a "floor brick" albeit smaller and lighter than the original(see paragraph 2 of my original post). Moreover, you're locked into that supply or finding a similar supply with the same rails and 5-pin DIN power connector. My solution will allow a broad range of popular wall supplies, possibly many so compact that they plug in without obstructing other outlets on the wall or power strip as well as a range of voltage and current compatibility provided the total power is enough for the user's system(again needs will vary from user to user). All with a common 5mm(or 5.5mm I forget) OD, 2.1 or 2.5mm ID barrel type power connector at the back of the unit. I believe this provides the broadest appeal as many users can repurpose one of the may power adapters they already have laying around. • Also, just a comment on MeanWell - I've seen some of their supplies. They appear to make cheaper "knockoffs" of supplies made by a more reputable company, CUI. However I've seen differences when comparing the two supplies as an exercise for a product team I worked on. They often use cheaper or smaller caps for the large bulk caps needed in such supplies, including caps with lower hour use lifetime ratings. Sometimes omit components that are not "strictly necessary", but improve the reliability or the quality of the power(ripple, droop, etc). I'm not a power supply expert, but I've had quite a bit of exposure to people who are and I've learned just enough from them to make good quality DC/DC switchers for my own projects and for projects I work on at my day job. • Finally, this project is actually the core of three power supply projects which are not form factor compatible, but It would be desirable to share the individual switcher designs for once these have been tested/characterized. The TI-99 supply is first because it's the simplest of the three. I also plan a redesign of the internal switcher for the Apple IIc, so that it can be used with a smaller external adapter, preferably the same unit I'll use for my TI so I only need one packed in my vintage computer "trunk". The third is a full analog board/flat panel conversion for the Macintosh Color Classic. I'll probably need a beefier external adapter for that as the backlight for the TFT adds several watts to the total power as well as possibly needing to still support mechanical SCSI drives(although for my own unit, I'll probably also swap in an SDCard based replacement). Again, not trying to knock anyone else's suggestions, but I believe the unit I'm designing will both have the broadest appeal for the many who just play with their vintage TI's plus some reasonable amount of additional capability for those who want to develop things that draw power from the side port(Maybe someone wants to redesign the CF7+ or Nano PEB to draw power from the console instead of needing the external 5V supply?).
  17. Doing my best Walter Skinner(imagine the words mumbled and slurred together): "for-the-purpose-of?..." In all seriousness, I don't see this as being something that most would want. There's a sizable gap between, "while my machine is open anyway" and "I think I'll hack a hole in the side to mount a panel mounted USB power port... Still, I'm sure I'll have test headers on the board for all rails, so if someone wants to add additional harni (Plural for harness? :P) they can knock themselves out. I'm still going to fix the max 5V at 2.0A, though. That's plenty for the console's current(ha! a pun!) needs plus 500mA for the side port and 500mA I guess for a USB port like you want above...
  18. Indeed it appears it does! That was hiding near the middle of the schematic page where the scanner misses the binding edges of the pages in the middle... I don't own a modulator to test, but I suspect it does not draw a significant additional load, and the attach rate is going to be pretty low on these. I'm guessing the "purist" crowd that still attaches these via the RF modulator is going to prefer the original TI power brick as well...
  19. OK I've some some more research including looking at the scanned document with the TI Console Technical Requirements and here's what I found: The +12V does not appear to leave the console - It goes to the TMS9900, The DRAM Chips, Some pullup network on the GROM Bus(looks like precharge bus parking for the normally open collector data bus) and a clock generator chip. So... It would appear that I really do not need to provide any additional power capacity beyond the 250mA I originally measured. Also, the tolerance appears to be +/-10%, so that rail could be as low as 10.8V and the components would operate normally. This means I could use a very Low drop out voltage regulator with a 12V input supply and as long as the LDO output is a tighter tolerance operation would be satisfactory. I still may also add an option for a low current boost regulator to see if really small power plug type wall adapters can work(at least on the main console). I may be able to use a voltage doubler or tripler at this low current draw followed by an LDO or just a filter. I'll play around with some circuits to see... On the +/-5V rails at the side I/O connector. Those are documented as being meant ONLY for the speech synthesizer and spec 50mA each Max. The PEB clearly has it's own hefty internal supply and does not draw from these. Even the circuitry on the flex cable derive their power from the +8 that comes from the PEB. I'm guessing the many "Sidecar" expansion boxes offered had their own wall supplies or power cords as you can't run much off of 50mA, especially in the TTL and 5V CMOS days. So... My plan to roughly double the capacity of the low voltage rails from 1A to 2A on the +5 and from 100mA to 200mA on the -5 should be more than enough. In fact there may or may not be trace width constraints on the PCB traces that prevent drawing too much additional power anyway! There will be more than enough power to accommodate anything that has already been designed to draw power from the side port and maybe even allow for devices that previously required their own wall adapters to run from console power. I'd probably limit that to the <500mA that a R-Pi draws, though. On top of that, I've decided for the sake of simplicity not to add any fancy "soft power" features or the like. Anything that requires hacking wires out of the box or onto the other circuits in the console is an anti-goal. 99.4a% of the people are going to be just fine flicking a mechanical switch like they always did in exchange for a perfectly fitting drop in board with zero soldering required. I will have some sort of LED color select-ability though. Perhaps just jumpers or a DIP switch to "mix" colors allowing for 7 colors? Something fun and unique so that from the outside you know you have a little something special under the hood. 😎
  20. Oh sure, I wasn't reading your commentary in a negative way. I just believe that the solution with the broadest appeal(as broad as can be for these old machines) is a drop in solution which works with a large variety of external supplies. Some users, like console + cart only, will be able to get by with a very small, low power wall adapter, but the internal supplies wil be able to handle reasonably higher loads provided a larger wattage external adapter is paired with it. That's the beauty of switching power supplies, they are very adaptable as long as you don't exceed the maximum output power. Some will be quite a bit less efficient at very low power draw or will go into power saving modes that are noisier, but we don't have to worry about that as our machines don't have any dynamic power saving modes like modern machines, so these supplies will be running at very high efficiencies and will only generate a fraction of the heat that the original linear supplies do...
  21. I did look up resistive and capacitive "transformer-less" supplies and what I found were worse than either liner or switching supplies. They are horribly inefficient and suitable only for very small loads before significant voltage drops. I believe this explains a lot of very small but super cheap wall supplies I've come across... But again, to the regulator the load is just some perceived impedance(the more dynamic term for resistance outside of static resistive only loads). Ohms law dictates that the supply cannot "push" extra power into the load outside of a critical component failure, so the some fault or failure would have to precede the supply delivering more power than normally needed, which could, of course create additional component failures in either the load circuit or the power supply. Still, even in the short circuit case, no power supply can supply infinite current. Many supply designs will just "fall flat" and not necessarily create smoke and fire. Virtually all modern regulator ICs have built in fault protection usually in the form of thermal shut down as well as often having over-voltage and under-voltage lockouts. The ones i plan to use are probably only going to have thermal protection, but the PTC fuses should add some additional protection. In fact they are designed similar to your resistive supply desired behavior. When the current exceeds a threshold, they heat up which raises their normally near zero resistance, thereby limiting current flow. Except unlike the resistive supply, under the normal range of current draw they have no virtually resistance/voltage drop. If you have a continuous fault, you have other problems, of course, but both the load board and the power supply are protected from additional damage.
  22. Well, I had written a very long winded response, but it didn't stick. I guess that's the forum's way of telling me to be less verbose I'll give a much shorter answer this time and invite any follow up questions: • Despite the term power "supply", it is the load that determines how much power is "drawn". It's not possible for the supply to "force" too much power into the board. If the load circuit has no faults(shorted capacitor for instance), then it will draw only what it needs. • There is no danger in interfacing modern silicon with stronger output drivers or faster(shorter) propagation delays/speeds from an electrical standpoint. The load receiving circuit will only draw what it "needs". Faster logic may cause improper timing operation if the original design is trying to "cleverly" exploit known propagation delays(ie chain of buffers for delay or feedback inverters for oscillators). That would be more likely to just cause improper operation than circuit damage, though. There can be exceptions of course(bus contention/overlap due to higher speeds). • If the power supply voltage is drooping under load(like a resistive supply would) that actually CAN damage circuitry. There are some cases where the load requires fixed power where if the voltage drops, more current is drawn which can exceed resistor power dissipation, or Diode/Transistor maximum current. Also voltage drops in digital circuitry will decrease the signal to noise ratio and result in bit errors/flaky behavior. One of the reasons a line level brown out damages some electronic equipment is because as the voltage drops, current increases to draw constant power. • The best way to prevent overloads is to put fuses or active current limiting circuits on the supply outputs! I plan to put Poly Thermal Fuses on my supply design. They "auto reset" when they cool down. • The supply Im designing, while having significant overhead to accommodate some external devices will likely deliver less max current in a short circuit condition than the OEM supply, so it should be much more reliable and even safer for our aging consoles. I'll probably do some "destructive" testing on an OEM unit as part of my research... Hope this helps explain some of how this stuff works. If anyone wants, I can give a primer on the differences between linear supply operation and switching supply operation 😎
  23. Heat won't be a problem with the board I'm designing. Modern switching supplies can be 90+% efficient. Any fully external solution that provides clean rails will be a brick. Any modern 32K expansion should draw less than 100mA and the TiPi is probably less than 500mA. I have two candidates for the 5V switching supply, one is rated for 2A and one for 3A, the console+parsec only draws 1A, so we'l have plenty of margin there...
  24. I'm pretty sure I can find a way to make this supply run on 12VDC Input. Especially since the 12V rail usually has a higher tolerance than he 5V rail. I've seen +/-10% specified for some older computers 12V supplies, so we could be as low as 10.8V and still have no operating problems. With an LDO for the 12V rail at the typical low current draw I'm seeing, I could probably supply a well regulated 11.7V or so which should be more than fine. One should be able to power their TI-99 from a car battery with the board I'm designing. Not sure what you mean by resistive power supply. Can you elaborate on what that is and how it would protect older components on the main board?
  25. My TI wall adapter(not the floor one with the extra fuse) doesn't have an input power rating, but it has the output power as: 18.0VAC 22.0VA ; 7.5VAC 1.0VA. A volt-amp is basically a Watt, so the output power is 23Watts. Oh wait. The input amperage is 0.3A so at 120V, yes that's 36W! Maybe the floor bricks use a bit more. That means that even the transformer is burning power. That makes sense, the transformer is a pair of coils - the old transformers always "Buzz" and have vibration, that's actually mechanical energy with converts to heat as well and is not delivered to the outputs. So, even more reason to design something that uses both a modern switching type AC/DC at the wall + modern high efficiency switching DC/DC regulators inside the console. Maybe I can make our TI-99's "Energy Star" rated?
  • Create New...