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Forum section: electronics / projects

author: masterburner
author_rank: Contributor
timestamp: March 09, 2011, 06:44:30 pm
content: After lurking the EEVblog since it started, I figured it was time to create an account.Right, lets see if this works on this forum as well. Post a picture of the project you're currently working on (or a recently finished project, of course). Here, I'll go first: my latest, finished project, is this CMOS clock (no TTL, sorry...) because I didn't have enough clocks on my room just yet (about 5 now... anyone else having the same clock-fetish?).The clock itsself:http://dl.dropbox.com/u/699251/cmos%20klok/IMG_1142.JPGThe power supply:http://dl.dropbox.com/u/699251/cmos%20klok/IMG_1143.JPGThe back of the PCB, etched it myself:http://dl.dropbox.com/u/699251/cmos%20klok/IMG_1159.JPGAnd this is what the PCB looks like in eagle:http://dl.dropbox.com/u/699251/cmos%20klok/ttl%20clock.pngThe clock uses the 50Hz mains frequency as time base. This gets devided to a 1Hz puls using 2 4017's. The counting is done with the 4510 and the bdc --> 7 segment decoding is done with a 4543. It uses diode AND-gates, because I didn't want to spam more ICs on there... Had a great time drilling all those holes.I designed it myself. If anyone wants the schematics/pcb (eagle), just ask.There we go. Now it's your turn. Show your project.

author: david77
author_rank: Frequent Contributor
timestamp: March 09, 2011, 07:02:40 pm
content: Nicely done! I love a proper IC graveI've still got my Nixie Tube Clock (circuit by mikeselectricstuff) that I built many years ago. Sadly it stopped working and I never had the nerve to troubleshoot it.I'll add some photos later.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 09, 2011, 09:40:17 pm
content: Hybrid Digital audio amplifier:http://ecorenovator.org/forum/appliances-gadgets/358-amanda-harris-prius-home-audio.htmlAnother Hybrid Digital audio amplifier:http://ecorenovator.org/forum/appliances-gadgets/984-allie-moore-ihybrid-40-next-generation-ti-hybrid-digital.htmlOne mod to a cheap wireless router: (One of my current projects)http://www.dd-wrt.com/wiki/index.php/Serial_port_on_unused_Ethernet_pinsI also have a lot of smaller projects that I don't have any real documentation for, as well as my current alternative energy exercise bicycle project that currently doesn't have much to show, apart from the generator assembly itself.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 10, 2011, 05:39:58 am
content: Quote from: NiHaoMike on March 09, 2011, 09:40:17 pmnice idea! you can be a millionaire selling this product. btw, did you make whole thing by yourself? i mean welding the metal yourself?

author: wasssup1990
author_rank: Contributor
timestamp: March 10, 2011, 09:28:54 am
content: Quote from: NiHaoMike on March 09, 2011, 09:40:17 pmHehe. You have Britney Spears playing in the first link. I listen to her music pretty much daily. Would you hold it against me?Wow! Looking at the preview, this forum automatically embeds youtube videos! Fantastic!I'll get some pictures together and post some of my projects.

author: wasssup1990
author_rank: Contributor
timestamp: March 10, 2011, 09:35:52 am
content: Ok here is a video I made about 3 years ago when I was 18. It is a controller board for a balancing robot that I made. It wasn't for school or Uni. Just a private project.I think it speaks for itself. Ask questions if it doesn't.

author: Unknown
author_rank: Unknown
timestamp: March 10, 2011, 01:27:49 pm
content: Quote from: wasssup1990 on March 10, 2011, 09:28:54 amI would.Here is one of my HV projects from back when I was 17. It's a 6-stage Marx generator fed by a 10kV, 20mA RMS oil-burner transformer which had some of it current limiting removed. Peak voltage is about 85kV.For safety I made a remote controlled power supply. Here you can see the prototyping and the finished boards. The remote is based on a 555 and the receiver is all 4000 series logic flip-flops and NOT gates. Thumbs up for high density layout.I also made a high-voltage bridge rectifier for it out of common diodes.And here is a DIY dual high voltage fuse. I used the wire from a normal fuse rated at the capacity I wanted and then used a 'Jacob's ladder' arrangement to quech the arc. Thumb this up for awesomeness

author: masterburner
author_rank: Contributor
timestamp: March 10, 2011, 06:25:45 pm
content: Quote from: Alex on March 10, 2011, 01:27:49 pmHow does one measure such high voltages? Or is this purely based on calculations?Nice looking enclosures, they look really clean and tidy.

author: Neilm
author_rank: Super Contributor
timestamp: March 10, 2011, 07:12:27 pm
content: Measuring voltages that high is easy - use a potential divider. All you have to do is find a high voltage resistor for the top.http://www.welwyn-tt.com/pdf/datasheet/HVP.pdfQuite often these will need to be treated before they can be taken to full voltage. For example being immersed in oil or resin.Neil

author: Time
author_rank: Frequent Contributor
timestamp: March 10, 2011, 08:34:14 pm
content: Quote from: Alex on March 10, 2011, 01:27:49 pmWhats the errected capacitance of your marx?

author: Time
author_rank: Frequent Contributor
timestamp: March 10, 2011, 08:35:20 pm
content: Quote from: wasssup1990 on March 10, 2011, 09:28:54 amgtfo

author: Zero999
author_rank: Super Contributor
timestamp: March 10, 2011, 08:51:33 pm
content: So what if he likes Brittany Spears? I think some of her music is annoying but he's entitled to his opinion.Quote from: masterburner on March 09, 2011, 06:44:30 pmI can't see any decoupling capacitors across the ICs, you were lucky it worked so well.Nice project, blue wouldn't be my choice of colour but still a good project.QuoteAND/OR gate ICs are a waste of money in my opinion. Just about any logic function can be made with NOT gates and resistors. Diode gates are often good but you need to be aware of their limitations.

author: Unknown
author_rank: Unknown
timestamp: March 10, 2011, 08:58:58 pm
content: Quote from: Time on March 10, 2011, 08:34:14 pmEach stage is 4x 10nF 7.5kV pulse rated Cornell Dubilier capacitors. Two caps connected in series, an then in parallel. So each stage is 10nF 15kV. 6 stages charged in parallel, discharged in series, thats 6.75 Joules - losses and residual charge per pulse.

author: Time
author_rank: Frequent Contributor
timestamp: March 10, 2011, 09:09:58 pm
content: coulda just said 1.67 nF, lol

author: Unknown
author_rank: Unknown
timestamp: March 10, 2011, 09:12:45 pm
content: I did not understand your question so I gave you all the info to answer a broader set of possible questions yourself.You did that, excellent!

author: wasssup1990
author_rank: Contributor
timestamp: March 11, 2011, 02:52:29 am
content: Wow! Excellent looking project (Marx Gen). Hey why don't you modulate your sparks with Britney Spears! LOL!

author: wasssup1990
author_rank: Contributor
timestamp: March 11, 2011, 05:57:34 am
content: Here is my current project. It's a power inverter.

author: oPossum
author_rank: Super Contributor
timestamp: March 11, 2011, 08:18:01 am
content: A few old projects...TheIR Widget- IR remote control capture.Uses a simple technique that can be implemented on almost any microcontroller or even with a few 74HCxx chips. Measures carrier frequency and burst durations simultaneously.Closed Caption Decoder- Converts NTSC closed caption and XDS data to serial.A current project...The Freeduio Flex - an Arduino clone with flexible build options.I am too cheap (Dutch) to pay $30 for the real thing.

author: masterburner
author_rank: Contributor
timestamp: March 13, 2011, 10:12:52 am
content: I'm probably a bit late with this project, as the whole LED cube craze seems to have died around the internet, but what the heck...The LED cube its self (it's not that bad looking in real life... Really)http://dl.dropbox.com/u/699251/led%20cube/IMG_1220.JPGOne of 2 row driver boards:http://dl.dropbox.com/u/699251/led%20cube/IMG_1221.JPGContains a bunch of 74HC595 shift registers and high-side driver IC's.Back of the row driver:http://dl.dropbox.com/u/699251/led%20cube/IMG_1226.JPGThis is the column, or "floor" driver board:http://dl.dropbox.com/u/699251/led%20cube/IMG_1223.JPGAnd the back side of the column driver:http://dl.dropbox.com/u/699251/led%20cube/IMG_1225.JPGYes, I made a mistake. I swapped the clock and latch pins of the 74HC595...And a shot of my current setup:http://dl.dropbox.com/u/699251/led%20cube/IMG_1228.JPGI've etched these boards myself (fast TAT, wheeej).The breadboard contains a 16F876 (way more then I need, a 16F628 will be used in the final version of my design). I still need to design the PCB for the microcontroller, as I'm not entirely sure on what I want to do with it. I also need to etch the PCB for the power supply (LM2575 switcher + transformer) and I need to box the whole thing up in a nice wooden enclosure.But this project is kind of on hold, because I'm already working on a school project. And I found one of these on a trade show, yesterday:http://dl.dropbox.com/u/699251/IMG_1229.JPG(The picture above shows 2 boards next to eachother)5 euro for eight 8*8 led matrices WITH driver circuitry on the back:http://dl.dropbox.com/u/699251/IMG_1230.JPGAnd they still work! Crazy...Need to mess around with that, first. No datasheet, but it shouldn't be to hard to figure out. Looks like more shift register and 2 multiplexers.

author: racerxdl
author_rank: Newbie
timestamp: March 13, 2011, 05:11:48 pm
content: Heey, very good projects! Lets post mine:Recently "finished" (is for a presentation):Its a Virtual RS232 Terminal, a FPGA Receiving the signal from a PS2 Keyboard decoding to ascii and sending via Serial. Also, It receives the chars from Serial Port, and write on a internal RAM at FPGA.There is a video generator for a LVDS LCD too, that reads the ram and make a few other things to display, here is a video of a linux terminal at rs232:And the project at OpenCores:http://opencores.org/project,virtual_rs232_terminal_with_lvds_lcdAnd document explaing how did I control the LCD Screen:http://translate.google.com/translate?hl=pt-BR&sl=pt&tl=en&u=http%3A%2F%2Fwww.energylabs.com.br%2Fel%2Fver-documento%2F902An other projects is a Musical Double Ressoand Solid State Tesla Coil, that is working very good now. Here is a video of the coil playing StarWars Theme:

author: johnwa
author_rank: Frequent Contributor
timestamp: March 20, 2011, 05:32:42 am
content: OK, here is my latest project (still a work in progress). It is a home automation bus system, using RS-485 communication. I didn't really like the look of any of the existing RS-485 bus protocols (modbus, etc), so I have implemented my own line-based ASCII protocol. Each node is controlled by an ATMega168, and this provides a number of analogue/digital inputs and outputs. The digital outputs have MOSFET drivers, and there is a +24V supply over the Cat 5 wiring for low power loads. So far, the basic bus communications are working, but I need to work on the software for the host computer. I am planning to set up a web based control panel eventually.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: March 27, 2011, 11:19:43 pm
content: A couple of years old, but I built 2 of these 1176 units which are in constant use when mixing:Full details here:http://www.axtsystems.com/index.php?option=com_content&view=category&id=34&Itemid=62

author: DrGeoff
author_rank: Frequent Contributor
timestamp: March 29, 2011, 01:03:30 am
content: This is a control module, primarily being used in home automation and monitoring. Ethernet (10bT) connectivity, 16 inputs, 16 outputs, 4 analogue inputs, 4 1-wire inputs, counter input, RS232+RS485 ports.The I/O conditioning and termination method is contained on a small termination module attached to the appropriate IDC header. I found this more flexible than incorporating it onto the same PCB since some nodes only require a few I/O and others require much more. Hence termination modules can be fitted as required. Also allows more flexibility with different enclosures.I've also developed a complete database and web based UI with trending on analogues, control logic and triggers etc. Several of these have been running non-stop for a couple of years now.The MCU is the PIC18F8722 and the ethernet controller is the ENC28J60. A 128KBx8 static ram device is used to buffer messages if there is a network disruption. Protocol is UDP/IP with AES encryption and error checking/retry mechnism built into the application protocol. This allows for a very low stack footprint.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 29, 2011, 01:39:50 am
content: Quote from: DrGeoff on March 29, 2011, 01:03:30 amA+++

author: wosser
author_rank: Contributor
timestamp: March 31, 2011, 06:22:24 pm
content: Hi guys, I've just released my design for a prototype toy "drift racing" car. It's a three-wheeled radio control compatible vehicle featuring Omni Wheels.I've not built it yet but I have released the DXF schematics on my blog under the Gnu GPL open source license.Here:http://wardyprojects.blogspot.com/2011/03/drifter-vehicle-schematics-first-draft.htmlHopefully it'll be suitable for indoor-use since the speed will be quite low, but it's expandable and simple enough to allow pretty much any power upgrade you can think of.It'll be pretty obvious after a quick glance that I'm a nooby to actually physically making stuff, so I don't even know if this machine will even remotely work, but it's going to be fun finding out.I'd love to hear what you guys think

author: johnwa
author_rank: Frequent Contributor
timestamp: April 02, 2011, 01:45:22 pm
content: DrGeoff, it looks like your home automation system is considerably more high tech than mine! Ethernet is probably a good way to do it really, but I was looking for something simple and low cost for my system. Mine is all cleartext, I am not too worried about anyone hacking into my toaster at this point...What language did you use for the nodes and the control software? And what have you got them hooked up to?

author: DrGeoff
author_rank: Frequent Contributor
timestamp: April 02, 2011, 10:09:23 pm
content: Quote from: johnwa on April 02, 2011, 01:45:22 pmI originally had an RS422 multidrop system (38400 baud) with an ascii text protocol from about 1995 for 10 years. This worked extremely well, however when I wanted to increase the number of nodes and include analogue inputs I had to sacrifice response time. These were simple cheap nodes based on a PIC16F877. They communicated with a master controller which was a 68302 based control unit. This drew very little power and could easily be battery backed. I used a terminal to connect to this and it was all ascii menu driven. The node and protocol details can be found here:http://www.axtsystems.com/index.php?option=com_content&view=category&id=41:projrtu4&Itemid=73&layout=defaultWith the introduction of low cost ethernet devices (originally used the Realtek device for prototyping) and more powerful processors I decided to switch to ethernet (10bT was plenty for this type of system) and use the ENC28J60 device. It also meant that I could switch from a poll-response based protocol to a remote call-in protocol. I also removed the master control box from the system and connect directly to a server. This allowed a greater level of flexibility in UI and DB options. I use MySQL as the core DB and the UI is all web based, written in PHP. This means I can connect to it from anywhere in the world to monitor what is going on.Quote from: johnwa on April 02, 2011, 01:45:22 pmThe node software is all written in C, since I ended up using a stripped version of the Microchip IP stack for speed of development. I developed a co-operative multitasking (state machine based) system to handle the internal DB and various concurrent tasks running on the remote nodes.The nodes themselves perform a lot of monitoring.I have a couple of light sensors to measure external light levels, many temperature sensors to monitor temperature profiles through the house (just built a new house and am effectively testing the prototype thermal design) and also measuring temperatures around the solar heat exchange hot water system. There are also the usual door reeds and PIR devices. I have a couple of pressure based tank water level sensors that I'm prototyping at the moment to measure the levels in the large water tanks.Controls are a few room lights, sprinkler and watering system valves, external lighting, pumps etc wherever appropriate.- Geoff

author: dakiller
author_rank: Contributor
timestamp: April 13, 2011, 03:07:29 pm
content: Last project I finished was a uni project last year, a Rubiks cube solving robot.Whole thing was designed and built by us from scratch (group of 6). Made from laser cut perspex, driven by 100W 24v DC motors, PWM control from a state-space positional feedback control loop with 8000pulse/rev encoder, running on a MEGA1281 AVR, both control loops at 13.3khz and robot management all on the mcu (multi-threaded RTOS), 90degree step response of 0.08s <1% overshoot with the 10A power supply being the limit. Serial link to a PC with a camera doing the image recognition and the cube solving algorithm. Time from start to finish to capture, analyse and solve is about 7.5 secondsJVwx3Lt-8_s

author: jacket
author_rank: Newbie
timestamp: April 13, 2011, 03:33:41 pm
content: BTS environment monitor and control, big project, continues some month. and we want to improve thishttp://www.cqbluejay.com/view_91.html

author: DrGeoff
author_rank: Frequent Contributor
timestamp: April 13, 2011, 10:58:45 pm
content: Quote from: dakiller on April 13, 2011, 03:07:29 pmVery cool. I assume that the camera and cube-solving is done on the PC, which in turn feeds the cube rotation information to the robot motor MPU via the serial link?

author: dakiller
author_rank: Contributor
timestamp: April 14, 2011, 12:12:01 am
content: Quote from: DrGeoff on April 13, 2011, 10:58:45 pmYes, the PC sends a list of cube face turns, L R U D F B in either clockwise or anti-clockwise and the MCU takes care of the management of which robot moves needs to be done from there (with a big complex lookup table that is 24*12*3 which tracks its state). There is also a bunch of other control commands like turn speed and turns designed for the initial camera capturing, pause, reset, etc. The PC image capturing is a fixed 3*3 grid on the screen that the cube has to line up in and the average colour is taken, but we also wrote a fully tracking cube capture that will track a cube face on the screen that can be used for hand capturing a cube into the PC

author: DrGeoff
author_rank: Frequent Contributor
timestamp: February 20, 2013, 01:43:58 am
content: Another studio project.A very low noise, clean 4-channel mic preamp. Very pleased with this one. The inserts allow me to add compression and distortion where necessary during tracking, particularly when re-amping for effects.More info here:http://www.axtsystems.com/index.php?option=com_content&view=category&id=56&Itemid=89

author: amspire
author_rank: Super Contributor
timestamp: February 20, 2013, 07:51:58 am
content: Dr Geoff,Thanks for posting your preamp. I had never heard of a THAT1512 but it looks very impressive and you have done a great job.The internal wiring can be a real mess in a preamp, and I think you have done a really good job. It all looks extremely serviceable.I was a bit concerned by the use of a 40V LM317 in the -48V supply. If the supply gets a momentary short, the LM317 will short internally due to the over voltage exposing the attached condenser microphones to the unregulated rectified mains. Given the poor regulation of small mains transformers, I am assuming the rectified voltage from the 18+18V transformer can probably reach 65V under light loads. I do not know if that is enough to damage microphones or not.You may want to consider adding a fuse and a crowbar as protection for the external mikes. There is nothing to warn you the regulator is shorted, unless D8 is an overvoltage warning light and not an indicator light.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: February 20, 2013, 08:03:48 am
content: Quote from: amspire on February 20, 2013, 07:51:58 amThanks,The LM317 on the 48 supply is the HV part, which can handle up to 60V between input and output.The small 36VCT transformer only manages 52V under light load, and phantom powering 4 mics is still light load so load regulation is within spec.In addition, the phantom power system is not really a voltage source to microphones, there's a 6k8 resistor in each supply path (ie about 14mA short circuit current). Even if the regulator went short and there was 55-60V on the phantom supply, that voltage would not be present at the microphone due to the series resistance and the current being drawn by the microphone.

author: Christe4nM
author_rank: Unknown
timestamp: February 24, 2013, 03:42:13 pm
content: Quote from: dakiller on April 13, 2011, 03:07:29 pmIt took me a while to find the video, your "link" is very incomplete if I may say so.Great project though, and nice result!