Show us your unfinished project! - Page 1
Forum section: electronics / general

author: RoGeorge
author_rank: Super Contributor
timestamp: June 25, 2022, 01:37:39 pm
content: A push-to-talk intercom based on a TBA790k power amplifier IC.It's 40 years now, and still bump into its PCB here and there.

author: tooki
author_rank: Super Contributor
timestamp: June 25, 2022, 02:45:48 pm
content: IC you never got around to installing the IC.I’ll see myself out now.

author: timenutgoblin
author_rank: Regular Contributor
timestamp: June 25, 2022, 03:11:09 pm
content: Quote from: tooki on June 25, 2022, 02:45:48 pmIC what you did there

author: bd139
author_rank: Super Contributor
timestamp: June 25, 2022, 03:14:21 pm
content: It might be easier if I show you my finished projects....There. Done!

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 25, 2022, 03:16:14 pm
content: Well how about this one. Was supposed to be the control board for a home phone switching network. Never came round to wrap a single wireAbout the same era as yours.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 25, 2022, 03:28:12 pm
content: Or this one. Sits in the same box as the previous one but is only about 30 years old. Was meant to be a two camera to midi system, where a performance artist danced in front of the camera's and the system would translate movements to midi. A sort of early xbox kinectWas never finished due to illness and no one available to pick up the hardware project. It was eventually done with an Apple Macintosh and a video capture card.This is the camera capture board.And this the interface board for connecting it to an Atari Mega ST.The hardware was done, but the FPGA programming still needed a lot of work. Kept it with the idea to use it for something else, but now it is more sentiment.

author: xrunner
author_rank: Super Contributor
timestamp: June 25, 2022, 03:31:33 pm
content: A precision voltage reference (of some kind).Ended up buying a DMM Check Plus.

author: rfclown
author_rank: Frequent Contributor
timestamp: June 25, 2022, 03:33:24 pm
content: Mine doesn't look as old and crusty, but it's also about 40 years old. It was to be an expansion interface for a TRS-80. I'm sure I have the memory somewhere, but never finished.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 25, 2022, 03:42:29 pm
content: One more old one for the roadA somewhat illegal copy of an E! Grey Matter expansion card for the DX7IIFD. At the time it did not work when I installed it in my DX7IIFD and did not have the time to investigate the problem any further so it was thrown in a box. Couple of years back I picked it up again and decided to give it another try. Turned out there was a single bad connection on the flat cableDid not leave it in the DX7IIFD well because it is a bit risky and clumsy. Had the original board layout at hand to make a proper board though, and still could if I would like.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 25, 2022, 03:49:02 pm
content: Quote from: rfclown on June 25, 2022, 03:33:24 pmSomewhere in another box I also have a couple of "proper" boards I made for my TRS-80. An EPROM board to have a bunch of programs ready to be executed, a bit like the cartridges on a commodore or older Atari. But also a digital to analog converter with discrete logic and a board to control a drum machine. These where actually finished projects

author: pqass
author_rank: Super Contributor
timestamp: June 25, 2022, 04:35:12 pm
content: Bring out yer dead..... Bring out yer dead.....In '85 I really wanted my own bare metal micro. This 8085 card was the start (and end) of that dream. I got an XT clone the following year.I didn't breadboard any part of it; just direct to layout. I used rub-on transfers and tape, etched it myself (naturally), and used a Weller gun to stick it together. Someday I'll get around to buying an 8085 for it.

author: daqq
author_rank: Super Contributor
timestamp: June 25, 2022, 05:46:42 pm
content: A hardware based brainfuck* language interpreter. Did it some 12 years ago when I didn't have that good an understanding of logic design. Worked well in the simulation, in retrospect the flaws were obvious.* -https://en.wikipedia.org/wiki/Brainfuck

author: capt bullshot
author_rank: Super Contributor
timestamp: June 25, 2022, 06:03:54 pm
content: A data collection hub intended to replace a lot of separate boards in my home data aquisition system.Does quite a lot of temperature sensors of various types (Pt 1000, NTC, KTY, SHT21), voltage, current and digital I/O.Built this about 10 or 12 years ago, andguess what: though works indeed, the old boards are still in place

author: capt bullshot
author_rank: Super Contributor
timestamp: June 25, 2022, 06:09:21 pm
content: This one was intended as a central "networking" hub for the same system.It has 4 * CAN bus, 2 * RS485 and RS232 plus some supply switching and overload protection.It's working but never found its way into the system. Today there's a somewhat more sophisticated version that does Ethernet too in place of this one.

author: MarkL
author_rank: Unknown
timestamp: June 25, 2022, 06:49:17 pm
content: Here is my unfinished Z280 board than ran at 20MHz and had 2MB of memory. I only got so far as running a small debug monitor from EPROM, which was enough to test the memory design (it worked fine). The blank areas were for two dual-UARTs (DARTs), a floppy disk controller, a SCSI disk controller, and an RTC. It all just barely fit.The Z280 was backwards compatible with the 8080A and Z80A instruction set, so eventually I could run CPM and legacy applications on it. But the real attraction was that the Z280 was meant to be multi-user and multi-process, and had a full MMU to support it. My longer term plan was to get UZI280 running on it, which a version of Unix.I had all the parts to finish it. But after a few years on and off working on this, I finally gave up around 1995 in favor of just buying an x86 machine and running Slackware Linux. At the time I also found a Z80A emulator that ran on Linux at about 50x a real Z80A to support the legacy applications. In the CPU market, the Z280 was a flop and was either discontinued by Zilog or at least the writing was on the wall, I don't recall which. There was just no point in investing more time. RIP Z280 board.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: June 25, 2022, 08:55:04 pm
content: Whoaaaaa, some serious hardcore home projects here!This one is rather simpler. As a cheapskate, I built this bitbang Parallel port to SPI programmer for use with AVRDude. It worked... randomly. Maybe it was something to do with capacitances on the signal lines or, because I had used mostly recycled parts. In the end, I bought a five buck AVR ASP off ebay and plugged it into the USB port.

author: mclute0
author_rank: Regular Contributor
timestamp: June 25, 2022, 09:37:15 pm
content: um, go look in that pile over there....

author: jogri
author_rank: Frequent Contributor
timestamp: June 25, 2022, 10:10:51 pm
content: Between the bucket of unsorted RF components and cables from butchered spec ans, the HV supply with suspicious test leads coming out of it, the stack of disassembled lasers, the SMU with a nasty habit of trying to push 150 A through anything that you connect to it and my Rb oscillator i'll choose the latter due to creative methods of cooling expensive equipment: You need to dip the end of the aluminium rod into a bucket with ice water, otherwise it'll overheat. But it locks.

author: RJSV
author_rank: Super Contributor
timestamp: June 26, 2022, 07:41:04 pm
content: What is this ? The photo contains a messy pile of switching devices, where various (random) relationships has exhibited real-world functions, (like bit saving Flip-flops.The point being, in nature, and various nervous systems, there are large numbers of seemingly useless structures, such as nerve cells that fire into places that don't have receptors,...meanwhile other nerve cells wait, but never get signal traffic (there's probably some mechanism that slows down, or shrinks areas that aren't active, in the organism).I'm thinking that's all a part of evolutionary pressures,as those with too much excess might not succeed so well.Dollar Store features those.

author: RJSV
author_rank: Super Contributor
timestamp: June 26, 2022, 07:43:34 pm
content: This next photo shows, (more Dollar Store) those hook racks and 'napkin holders', after coat of paint, make for attractive and neatly laid out PROJECT.

author: RoGeorge
author_rank: Super Contributor
timestamp: June 26, 2022, 07:49:39 pm
content: They look like small solar-cells with a LED on the other side, like some sort of garden solar lights. I still don't get it, what are those?

author: bd139
author_rank: Super Contributor
timestamp: June 26, 2022, 07:50:40 pm
content: Found a picture of a pile of things I never finished, mostly receivers.Also got about 2/3 of the way through this and got bored. This one I might resurrect. It drew a bouncing ball on an analogue scope display.

author: RJSV
author_rank: Super Contributor
timestamp: June 26, 2022, 10:01:07 pm
content: RoGeorge, thanks for asking:Please also see, DODGY SECTION, first page, has Optical Bench Redux.Those are cheapo Solar Garden Lights, each having a small, shorter version of an AAA rechargeable. They have a 4-pin control IC, that, obviously, has some kind of voltage comparator, front end, that switches an inverted output,...at 222 khz near square wave.So, never mind, that it's AC output, I just call that an 'ON' state, and seems like input is also a light lift, as that 222 khz isn't seen (as AC), but rather, a simple, raw solar cell just gives a steady DC on (1.2 to 2.0 volts in direct sun), so I'm considering that as similar enough, to DC in DC out ...(even while that's not, technically, true.)Lots and lots of possibilities, like a 'Liquid Suspension' module, no wires, no power (no external pwr wires), and using a quite powerful, optically linked, component.Smart 'dust', self-organizing, likely proposed many years ago.

author: Peter Taylor
author_rank: Regular Contributor
timestamp: June 29, 2022, 09:14:40 pm
content: My unfinished electric buggy. It was entered into the Element 14 Design challenge but not followed through.

author: RJSV
author_rank: Super Contributor
timestamp: August 30, 2022, 06:32:46 pm
content: I've posted here before (pls see June 26), but having so much FUN with the unique packaging, that I hope others get inspiration, also.While this 'strays' into electrical / electronic components, the emphasis is to study optical logic, and convolution for imaging. For example, I take a header for LED output, using that for simple extension of a 'supplement' LED, to bring that logic signal to activate a following gate (individual lawn light).The saving grace in this whole effort, is fact that these gates act as inverters, and plus they can do analog summing, at the little solar voltaic cell.Photo shows partial assembly; the middle 'wall' of gates is intended as 4 by 7 or 28 total sensing gates.The whole structure is a 3-D network...but notice, the DIRECTION of signal flow or travel is virtually all one direction, (with occasional lateral connections, from column to column.). I think, maybe, that some biological neural systems are more random, with signal directions, but actually the Visual system do seem to have a 'lateral' layered structure with very defined direction, for the mass of RETINA nerves.All this visual process stuff makes me want to study biosciences more (I've purchased the book on 'Neurology fro Dummies).- - Rick B.

author: Gyro
author_rank: Super Contributor
timestamp: August 30, 2022, 07:19:32 pm
content: Still, after 6 years!https://www.eevblog.com/forum/projects/my-u-blox-lea-6t-based-gpsdo-(very-scruffy-initial-breadboard-stage)/

author: bingo600
author_rank: Super Contributor
timestamp: August 31, 2022, 03:30:38 pm
content: Quote from: Gyro on August 30, 2022, 07:19:32 pmWell you got a reply/hint fromLarsThat ought to count for something ..../Bingo

author: Squarewave
author_rank: Frequent Contributor
timestamp: August 31, 2022, 04:09:06 pm
content: I could show you my house, started it years ago as a project, still not finished.....

author: Gyro
author_rank: Super Contributor
timestamp: August 31, 2022, 04:41:06 pm
content: Quote from: bingo600 on August 31, 2022, 03:30:38 pmTrust me, it does. He was a great guy. I really should finish it for that reason if no other!

author: bsfeechannel
author_rank: Super Contributor
timestamp: November 24, 2022, 04:22:51 pm
content: You're looking at my bass guitar.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 24, 2022, 08:05:58 pm
content: Unfinished, yes.