hybridfree/eevblog-posts huggingface dataset:
Audio waveform on a CRT TV - Page 1
Forum section: electronics / projects

author: UncookedCorn
author_rank: Contributor
timestamp: September 06, 2024, 02:33:38 am
content: I am working on project to transform a CRT TV into an audio waveform display, using a Vintage 1984 Panasonic TRF-438P Desktop Television AM/FM Radio Alarm Clock. The video I’m following ishttps://youtu.be/bO-DWWFolPw?si=qiyMTYlono_kKcxKand I’m solely following the waveform to CRT instructions. We’re taking the horizontal wires from the TV and plugging them into the tda7297 amplifier, which is being powered by a 12V supply. The issue is that I’m seeing an extremely dim vertical line on the TV when the horizontal wires are disconnected, but the line is a bright horizontal one when the vertical wires are disconnected. No waveform is being displayed when we hook up the amplifier with the horizontal wires, using a 3-wire audio jack to an audio source.I’m struggling to understand what the issue would be and any help/assistance would be appreciated. Thank you.

author: moffy
author_rank: Super Contributor
timestamp: September 06, 2024, 02:49:09 am
content: One of the waveforms needs to be a sawtooth sweep with a blanking between each sawtooth and the other can be the signal, but it is very dependent upon the detail. The high voltages around a CRT can be shocking and possibly lethal, and some TVs have a live chassis. Do you have the experience or knowledge to know how to do this safely?

author: Ian.M
author_rank: Super Contributor
timestamp: September 06, 2024, 03:01:20 am
content: In most CRT TVs (and all low voltage ones I have seen) the line scan coils are an integral matched part of the line output circuit which also (via the line output transformer) generates all the high voltage supply rails used for the CRT cathode driver and gun bias, + final anode EHT voltage that actually accelerates the electron beam. You would need to replace them with a big inductor of about the same (measured) inductance and a saturation current greater than the peak flyback current to keep the voltages the same. Unless you can wind it yourself on a salvaged big ferrite core, it will *NOT* be cheap.TLDR: CRT TV to scope conversions are difficult and only reasonably practical for selected models that don't use line scan derived EHT.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 06, 2024, 09:07:51 am
content: I have a doorbell camera "flat CRT" waiting for a similar project, so will be seeing how you progress!
Augmented PCB Debugger (Feedback Requested) - Page 1
Forum section: electronics / projects

author: leymane
author_rank: Newbie
timestamp: May 09, 2024, 02:51:38 am
content: I am currently working on a smartphone app to help locate components on PCBs using visual overlay. This is an improvement over current methods that require the user to manually match the component locator to the board. The primary goal is to help users test and troubleshoot boards faster and easier.I made a youtube video to demonstrate my concept. Currently looking for feedback on if it would be useful to anyone. Any suggestions for improvements also welcome.Here is the video:

author: ataradov
author_rank: Super Contributor
timestamp: May 09, 2024, 03:28:08 am
content: Is this ever an issue? In most cases when I'm debugging a PCB, I have stuff in my hands (probes, soldering iron, etc), and holding the phone and messing with the app is the last thing I want to do.

author: Fire Doger
author_rank: Regular Contributor
timestamp: May 09, 2024, 04:16:27 am
content: I think it would be more useful if it was a web app and could work with any video feed like from thermal camera and accept common board files like the ones that BoardViewer supports

author: oPossum
author_rank: Super Contributor
timestamp: May 09, 2024, 04:19:48 am
content: https://www.flowcad.com/en/inspectar.htm

author: leymane
author_rank: Newbie
timestamp: May 10, 2024, 04:05:02 pm
content: Quote from: ataradov on May 09, 2024, 03:28:08 amWhat about hands-free, voice control? Here is a demo:

author: xvr
author_rank: Frequent Contributor
timestamp: May 10, 2024, 06:06:17 pm
content: Interesting idea. But in current form it more suitable for octopus, not humanAnd using phone as display is not convenient - we are only humans, not chameleons, and can't see in 2 (or even more) different directions simultaneously.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 10, 2024, 07:14:42 pm
content: Quote from: xvr on May 10, 2024, 06:06:17 pm

author: ajb
author_rank: Super Contributor
timestamp: May 10, 2024, 08:12:15 pm
content: It is definitely a cool project! But I agree with others that it would be more useful on a computer, which has the added benefit of being able to use a better (or at least more suitable) camera. What could be really cool is getting this sort of overlay in a microscope view, with the system keeping track of where the microscope FOV is on the PCB. I guess that would need a second larger FOV camera to track the board, but it could be very helpful when working at higher magnifications on a relatively dense board, where it can be hard to keep your bearings.
Augmented Reality breadboard circuit building - Page 1
Forum section: electronics / projects

author: billclay
author_rank: Regular Contributor
timestamp: November 10, 2013, 02:09:12 pm
content: I haven't seen this mentioned before, but it's very cool. Here's the blurb directly from theYT post:Augmented Reality app provides walk-though build instructions, part and net information overlays on real circuits.It seems to be similar to what is done in the manufacturing industry already:http://www.equipcodes.com/augmented-reality-for-equipment-manufacturers.html

author: Tinkerer
author_rank: Frequent Contributor
timestamp: November 10, 2013, 09:56:39 pm
content: Holy crap! I want that. This right here folks is the future staring us in the face.The one step up from this is basic projecting holograms on to the board but we havent quite reached that tech yet.

author: Zbig
author_rank: Frequent Contributor
timestamp: November 11, 2013, 01:12:41 pm
content: Maybe I'm getting old and grumpy way too fast but I actually hate the idea. It's a nice technology showcase stunt but it has zero educational value in my opinion. The last thing world needs is another flood of Arduino "projects" with breadboards permanently taped to them because the guys who "made" them not only weren't able to translate the breadboard to PCB but never actually understood why whichever wire goes where in the fist place. What's the next step? A robotic arm putting the wires into the breadboard for you while you lean back with a feeling of accomplishment? What if one runs out of the yellow jumper cables but still has plenty of blue ones left? He'll go straight to the eBay to order some more yellow ones, I guess. That's not learning, that's "drawing" by connecting the numbered dots. If there's a notice "Age 7-10" somewhere there then ok, I apologize, great kids' toy.

author: ddavidebor
author_rank: Super Contributor
timestamp: November 11, 2013, 01:18:40 pm
content: Quote from: Zbig on November 11, 2013, 01:12:41 pmI agree with you and i"m 17
Augmented Reality for PCB test/rework/assembly - Page 1
Forum section: electronics / projects

author: Inspectar
author_rank: Newbie
timestamp: August 12, 2019, 06:25:36 pm
content: Inspectar is an Augmented Reality application that you can bring into your electronics lab ( Don’t worry there’s no helmets or glasses involved) and make your work more efficient.https://inspectar.comMyself and my team started this project in the last year of our ECE degrees, and now that we’ve decided to go full time at this, were ready to share it with the world !I’m posting this here to get feedback from the eevblog community, would you try Inspectar in your lab? Do you work on a team that has firmware developers constantly pestering the hardware team for help probing boards? Do you delegate work to technicians, only to have to walk to their lab and show them where C12 is so they can do rework?P.s. To the mods, I’m sorry If i posted this in the wrong forum section !

author: Hiemal
author_rank: Regular Contributor
timestamp: August 13, 2019, 05:15:00 am
content: It certainly sounds interesting! I find that when I'm personally prototyping PCB boards for my own usage I'll have to look back and forth between the schematic on my computer and the actual board itself.This cuts that process out completely and would really be useful. I hope it won't be expensive for individuals as a sidenote.

author: Inspectar
author_rank: Newbie
timestamp: August 13, 2019, 09:53:35 pm
content: Love to hear that you can see the use-case, appreciate the feedback ! We're actually heavily focused on monetizing this for enterprise, and our goals for individuals are more of a marketing play. We'd love to see as many people as are interested in using it, using it ! As such, we're currently looking at what feature set we're going to give for free to individuals ! You can sign-up to our wait-list and we'll let you know when it's readyhttps://www.inspectar.com/beta

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 14, 2019, 05:26:34 am
content: how can we transfer components information to this SW from Altium, KiCAD, Eagle, etc? automated tool/feature? how? or manual typing one by one?

author: Inspectar
author_rank: Newbie
timestamp: August 14, 2019, 03:11:43 pm
content: Aside from generic information available in Gerber X2 or IPC2581, we support parsing a paired BOM file. At minimum we want a column with the component reference and the MPN number of the component so we can request information from a 3rd party API like Digikey or Mouser.
AUS - LED panel suppliers - Page 1
Forum section: electronics / projects

author: John B
author_rank: Frequent Contributor
timestamp: September 11, 2020, 10:55:38 am
content: I've been trying to find some good suppliers for LED panel lights in Australia, specifically LED panels that have separate driver units, and ideally high CRI 90 or better. I did note the link to a store when Dave retrofitted a bunch of new LED panels in his workspace, but a few more recommendations would be good.
Australian ac-dc power adapters - Page 1
Forum section: electronics / projects

author: Alex30
author_rank: Regular Contributor
timestamp: August 26, 2014, 09:48:14 am
content: I'm just wondering where I can get a good 15V DC 2A adapter (because i'm reluctant to mess around with mains power for my project)? I am after a CE certified (quality) adapter but it seems like the shops in australia such as jaycar charge through the nose for this kind of stuff ($30 AUD). Is there any cheap supplier anyone uses for australian adapters that are CE certified and not chinese ripoffs? Not fussed if it's unregulated or regulated as I can work with either.
Australian Standards and Network Devices - Page 1
Forum section: electronics / projects

author: Gitch
author_rank: Newbie
timestamp: April 01, 2014, 08:17:41 am
content: Hey all,So I've built and testing a prototype idea that I am wanting maybe sell or supply... It is essentially a network device utilising PoE and IP communications that is physically fixed to part of a house but plugs into a network switch.Obviously I will require a C-tick of the RCM equivalent, but are there any other Standards I must abide by??Cheers

author: Neilm
author_rank: Super Contributor
timestamp: April 01, 2014, 07:51:40 pm
content: Find a test house reasonably near and give them a call. They should be able to point you in right direction. There are a lot of standards out there many of which could apply to a single product. (for instance a phone comes under standards applicable for making telephone calls, a computer comes comes under IT standards - so what if I install a VOIP package that allows me to call landlines?)And do please say where you are - I might be able to give reasonable advice if you are in the EU, but that might be wrong in other parts of the world.

author: kaindub
author_rank: Regular Contributor
timestamp: April 02, 2014, 05:16:47 am
content: Gitchhow many of these are you going to sell?There are exemptions for low volume items (I think 10 or less)if you are just supplying them as a kit, then it's not considered a product and the responsiblitiy for all aspects of compliance falls to the constructor. My you, constructors buying kits are not subjct to the same level of scrutiny as commercial products.What aspect of C tick do you think you need to meet? There are both safety and RFI standards that may apply.You also cannot get permission to apply C Tick unless you are a registered business. Are you?Unless you are goiing into a commercial venture where you will be selling lots of these, it's not necessaryRobert

author: David_AVD
author_rank: Super Contributor
timestamp: April 02, 2014, 09:54:39 am
content: Quote from: Neilm on April 01, 2014, 07:51:40 pmI'm guessing Australia, since the title does say "AustralianStandards and Network Devices".Quote from: kaindub on April 02, 2014, 05:16:47 amI've heard that line many times, but the quantity made has no relevance to the requirements, at least not in Australia.
Auto focus lens driver for image sensor - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: June 21, 2017, 05:39:58 am
content: Hello,I am developing a circuit where an image sensor (AR1335 CSP)http://www.onsemi.com/PowerSolutions/product.do?id=AR1335) acting as Master and processor (AP1302,http://www.onsemi.com/PowerSolutions/extSearch.do?query=AP1302&param1=type&param1_val=evalboard) is like a slave (ISP).One confusing fact was that, slave was connected with USB hub( CYUSB3065) which has been provided I2C signal to drive liquid lens driver MAX14574. In new design, I need to add those from master. Previously, master I2C signal was controlling LEDS.To drive the image sensor the following circuit is required,(See first diagram)I am expecting auto focus voltage output, that is clear on circuit.Dont you think its SDA and SCL pin should be connect from master? Lets say I am using level translator (TXSO102DQER) with pull up resistor between Master and lens driver. To understand my application, see the attached ( circuit 2)
Auto powersave - How to retrofit on older KRK Rokit active monitor? - Page 1
Forum section: electronics / projects

author: TinkeringSteve
author_rank: Frequent Contributor
timestamp: April 18, 2023, 02:58:29 pm
content: Helloooo,an understandably sometimes hated feature of newer models of the KRK Rokit active studio monitor speakers is the auto-power-off when there is no input signal for 30min or so.Here, someone modded his newer speaker to be able to (de-)activate it at will:https://www.eevblog.com/forum/repair/krk-rokit-5-g3-how-to-permanently-disable-the-auto-power-off-feature/Now, I won't have it that easy, because my 2nd gen or so model does not have that feature, and I can't just bridge some ICHow would you design a feature like that, to retrofit an older specimen with it?My hobbyist tinkerer's first thoughts:somepower will always be drawn, to be able to auto-turn-ON also, by detecting a signalunless..., then again, I wouldn't mind if it cannot do that and I had to press a button to re-enablethe latter would allow to save even more power, as no signal monitoring needs to go on, when it was switched offi.e. in that case, a relay may cut mains power from the 3-contact mains jack - probably also the easiest point to interceptdo even small relays, and DC ones, hum, due to whatever miniscule instability in the setup? Perhaps using a mechanically latching relay is advisable? Although I reckon they may have fewer guaranteed cycles than non-latching oneshow/where to tap the signal in the chain for detection, without introducing noise?is it too wild to assume the power supply in such a thing will have enough headroom to allow for the extra current draw of a relay? I think these still have analog amplifiers that draw a lot of current all the time, hence it seeming advisable to add this featuresignal dection/action could go like... comparator with certain threshold -> RC (dis-)charge for timing -> another comparator for disabling the power? (I normally just throw a cheap MCU at things, but it might add noise here)
Auto rainging shunt - Page 1
Forum section: electronics / projects

author: OM222O
author_rank: Frequent Contributor
timestamp: November 02, 2019, 01:30:45 pm
content: Hello everyone! I've designed a universal shunt resistor that can go between 1ohm to 100k ohm and currently the range is selected via driving mosfets via an MCU.I wanted to use some comparators to make it switch ranges automatically and this is the initial idea I came up with which is very similar to how the LM3914 works:http://tinyurl.com/yyg49czpby varying the pot, the comparators turn on and off, but this acts like the "bar mode" which isn't any good in my case. I want only one mosfet that corresponds to that range to be on. I'm not sure what logic I can use to get this conversion to happen but my best guess was using some XOR gates. This is probably embarrassingly simple to solve but I haven't figured it out yetAlso ideally I would like to add some threshold to prevent switching between 2 ranges rapidly when the value is close to the transition state, but I'm not sure how to that eitherEdit: I actually managed to get the dot mode working but it's not ideal. I have to either use 1 extra comparator , which messes up the ratios, or use a quad nand to create a NOT and an AND as well as 2 quad XORs. the second approach is more acceptable imho but it would be nice if there was a way to use all XORs without needing extra comparators.http://tinyurl.com/yxwzfglf
Auto Room Temp Controller - Page 1
Forum section: electronics / projects

author: easilyconfused
author_rank: Regular Contributor
timestamp: August 02, 2010, 01:29:43 am
content: I would like to build one (prototype) louvered floor register for one room that will open and close with an RC airplane servo motor as needed to attain a selected temperature. I'm pretty handy with acrylic (Plexiglas) and can easily build the register. But I need help in designing the circuit and writing the code. I suppose it would need some sort of limit switch so that the servos don't burn up trying to move a louver that's already fully open or fully closed. I have an Arduino and a servo motor. I'm willing to spend a little money to order what I need. The long (very long) range goal would be to have auto-louvers in every room in the house with the goal of equalizing temperatures. I would want the system to ultimately be wireless with a whole-house report on my computer. I don't know how to do any of that but I think the technology is out there. I saw thishttp://www.instructables.com/id/Digital... Regulator/ and thought I could probably use some of the things he used. Any suggestions would be appreciated.(I realize that the prototype as drawn would not be practical because you'd step on it or hit it with the vacuum cleaner and so forth. Those are details for later.)
Auto turn off circuit - Page 1
Forum section: electronics / projects

author: piwicode
author_rank: Newbie
timestamp: November 19, 2024, 09:16:09 pm
content: Hi,I designed a latch that can be turned on when shorting SW_ON pin to the ground and turned off when shorting SW_OFF pin to the ground.The idea is to wake-up when an RTC clock chip alarm triggers, then do some action including servo operation, and finally turn the power off.Please find the circuit attached.When operate from the button, the circuit works as expected, but when the AT328P tries to turn the system off shorting SW_OFF pin to the ground, I just get a reboot.I suspect that the AT328P gets under powered before the voltage gets low enough for the latch to change state.How would you troubleshoot this issue?Any suggestion?

author: Benta
author_rank: Super Contributor
timestamp: November 19, 2024, 09:24:05 pm
content: Your resistor values are far too high, especially R1. Try dividing them by 10 or even 100 before moving forward.You can always optimise afterwards.

author: Peabody
author_rank: Super Contributor
timestamp: November 19, 2024, 11:00:04 pm
content: I assume the purpose of R2 is to latch on the power. The problem with that on shutdown is if there is aggregate capacitance in the load circuit such that voltage declines slowly, then the NPN can be turned back on again by as little as 0.6V on its base when the Off button is released. The GPIO will go tristate when Vcc drops below about 2.5V, which leaves R2 in control.The alternative would be to eliminate R2, and have the 328P turn on the NPN as its first official act on bootup. Then when it's ready to shut down, it would just bring that GPIO low, or make it an input, and there would be nothing that could turn power back on again. You wouldn't need the Off button.And I agree that the R1 value is a bit high. I usually use 100K there.
Automated Function Test of PCBA - Page 1
Forum section: electronics / projects

author: guscrown
author_rank: Regular Contributor
timestamp: March 14, 2016, 06:22:59 pm
content: I have a board I'm designing for a project at work, this board has several power rails (24V, 12V, 5V, 3.3V) and each rail is being passed through a MOSFET to cut-off supply to devices when the machine is "OFF". In my old job, there was a team that used TestStand with some "homebrew" jig for testing the boards (they were making many thousand board per day). I kind of remember they were using some kind of Pogopins, this pins would make contact with test points on the bottom side of the board and they would supply the necessary voltages to "TURN ON" the board, and then they would measure whatever power rail/singal they wanted.I've looked at TI's website and the TestStand license is $5,000.00 which I'm OK with. But I don't know what I need to the Hardware side. I am guessing I need one of their DAQs, but they have too many options.Anyone out there already doing this that could help out and point me in the right direction?

author: dmills
author_rank: Super Contributor
timestamp: March 14, 2016, 09:27:09 pm
content: I have never used TestStand, but I do have some general observations about bed of nails testing.The key to a lot of such things is to include a JTAG chain around everything that supports it on the board, then you write your test sequence as a set of jtag commands (Over here,www.xjtag.comseem to be the big player with the good dev tools and support at many assembly houses).JTAG is fast and cheap if you have a few parts on the board that already support it, but you do usually need a few add ons to handle things like analogue rails and checking connectors if you want close to 100% test coverage. Sometimes a smallish programmable logic element that exists only to provide test access is actually worthwhile, and do try to make sure that memory clocks can all be gated by something in the jtag chain it makes testing connectivity to these parts very much easier.Regards, Dan.

author: Apollyon25_
author_rank: Regular Contributor
timestamp: March 15, 2016, 09:22:52 pm
content: Give your local NI sales guy a call and discuss with them.NI kit is industry standard for large scale testing and Labview/TestStand is pretty comprehensive.Without knowing your design in detail, I cannot recommend a good solution.Bear in mind, NI gear isn't at the cheap end of the spectrum. But, they do have a range of products covering a wide range of applications.

author: rx8pilot
author_rank: Super Contributor
timestamp: March 16, 2016, 04:41:37 am
content: I have been designing an NI/LabVIEW system for automated test. The cost is not trivial, but I believe it will pay for itself fairly quickly in my case.The estimated cost for my 'starter' system is well over $50k. I expect that if I go all in, it could be $100k. This is a combination of NI and 3rd party hardware along with various custom fixtures and training.Sent from my horrible mobile....
Automatic chain oilier  - Page 1
Forum section: electronics / projects

author: stefan_trekkie
author_rank: Contributor
timestamp: October 02, 2020, 12:37:07 pm
content: Hello to all..'long' time ago i was traveling on motorcycle and have been done with automatic oiller for the chain lubing proposes. Back then oiller had been done in very simple manner with timer 555 and potentiometer on the dash for manually choosing the quantity of the oil .. Of course with a N light and some stuffs for auto stop..Now i am back on adventure bike with chain and thinking of doing new one but automatic with measuring the engine rpms and automatically to increase or decrease the oil.I am busy in the moment but i will make the schematic in few days.p.s. The Oiller works as simple gas valve is opening and closing. The open time remains the same (experimentally determent time around 1s) but the off time is with decreasing intervalsWhether any of you have done something similar ? I will be happy to hear your thoughts about this.

author: joeqsmith
author_rank: Super Contributor
timestamp: October 03, 2020, 03:27:13 pm
content: Quote from: stefan_trekkie on October 02, 2020, 12:37:07 pmInteresting...I had an old 60's bike that had an oiler. Basically a valve going to the oil tank with a tube going down to the chain. You would adjust the value to drip the oil onto the chain. With the modern chains I am getting 20,000 or so miles on them. I just change out the chain and sprockets as a set once they have gone past the stretch marks. Obviously, all chains are not alike. The chain I use on the race bike for example, is not sealed and requires constant care but offer less drag.

author: stefan_trekkie
author_rank: Contributor
timestamp: December 23, 2020, 08:45:31 pm
content: Hello again. I am finally free of too much work on my new workshop and will build the oiler soon I was trying to keep it functional and simple as i see fit... It's not super final stage but... /in the PDF down below/So.. Automatic detection on above 3000 rpms /actually i thing that was even 2500 with that resistor/ and neutral light is stopping the oil too ... With most of the thing can be manually bypassedp.s. Sorry for the Cyrillic script .. Always forgetting

author: jc101
author_rank: Frequent Contributor
timestamp: December 23, 2020, 09:36:24 pm
content: Many years ago I fitted at Scottoiler to all my motorcycles, impressed to see they are still going.. scottoiler dot comThe basic model opened with the engine vacuum and a simple gravity feed. It seems they now also have fully electronic versions even with small pumps.
automatic electric, not software, speaker fill - Page 1
Forum section: electronics / projects

author: Lupin III.
author_rank: Contributor
timestamp: October 13, 2018, 01:14:16 pm
content: I have two audio outputs (F and R) on my PC connected to speakers. If there's a signal coming out of R, I'd like F output to go to F speakers and R output to R speakers. If there is no audio coming out of R, I would like the F signal to be routed to the R speakers as well. If there is an R signal it should be out put immidiately. If there is no R signal, it's ok or even preferred if it takes a few seconds to switch F through to R. The circuit should be 5V powered from the same PC.That was the technical description. Here's the reason why:I'm usually running stereo speakers connected to the F output for most things. But when listening to music or watching movies (which can have true surround, so I want those extra channels and not always a copy of the front ones) I have a second pair of rear speakers which are connected to the "rear" output jacks on my mainboard. Now there lies the problem. My mainboard has a crappy realtek audio chip. Apparently realtek hasn't managed to make a decent driver in a decade and fix the issues with software speaker fill (as a lot of google results will show you). While playing audio from a surround source is fine, to stereo the speaker fill either does nothing or distorts the output by applying echo and frequency filtering. Btw. speaker fill worked perfectly fine with a VIA audio chip and its drivers I had on my last mainboard.Any ideas how to achieve this? A double-pole-double-throw switch doesn't count. It's not automatic. I'm not crazy about audio quality. Everything will sound better than what realtek drivers are doing to my audio.

author: bob225
author_rank: Frequent Contributor
timestamp: October 13, 2018, 04:57:15 pm
content: Its down to either A. cheap speakers or b. not using the correct drivers and running the Realtek software or a combinationfit something like a sound blaster card either pcie or usb what will give you much better control and then disable the onboardTbh the surround will be simulated unless you have Dolby or Thx content9/10 I use headphones any other times I run it through my Pioneer A/V amp and custom Jamo 7.1 setup
Automatic Gain Controlling Op-Amp - Page 1
Forum section: electronics / projects

author: mapexmbirch
author_rank: Contributor
timestamp: December 06, 2016, 07:31:53 pm
content: Hi allI am doing a project where I need an op-amp to gain an AC signal between 0V and 3.3V for the ADC on a PIC. But the signal coming in is going to vary in amplitude. And I want to use the full range of the ADC to do give the DSP algorthm the best chance. I thought about having a RMS-DC chip then invert the DC voltage out somehow, so when the output goes up the control voltage goes down. Then feeding that control voltage into a variable gain op amp. All my simulations on LTSpice go unstable.Can anyone suggest any circuits that would work?Cheers

author: macboy
author_rank: Super Contributor
timestamp: December 06, 2016, 07:50:00 pm
content: Why not generate the gain control voltage from the PIC? If you detect clipping in the input signal, change the voltage to reduce gain. If the amplitude is too low, increase gain. You can use a PWM output with a simple RC filter (long time constant) for the control voltage. This way you also know when the signal is going to be disturbed/distorted by a gain change and respond accordingly if necessary.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 06, 2016, 07:59:54 pm
content: I would also consider controlling the gain from the µC. I would also consider a digital controlled gain, so something like steps of 1,2,4,8 or larger. There are ready made for this, like MCP6S91 or PGA2xx.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 06, 2016, 08:12:25 pm
content: Surely you mean "between 1.65 +/- (small quantity)V and 1.65 +/- 1.65V"?What is your signal? What bandwidth and range? Accuracy?Stepwise control should be fine. Note also you want to control by peak value, because peaks will get rounded off first (saturating the ADC input range). As opposed to RMS or average.Tim

author: rstofer
author_rank: Super Contributor
timestamp: December 06, 2016, 10:35:18 pm
content: You probably have to use one op amp to offset the incoming signal by 1/2 analog Vcc. Then use another op amp with variable gain to scale the output. You can use an analog switch and various resistor for the gain ratio.
Automatic Power Saver - Page 1
Forum section: electronics / projects

author: Radhuvir_G
author_rank: Newbie
timestamp: November 06, 2014, 12:52:46 pm
content: I've made the above circuit but the problem is my cat keeps trigering the device, are there any PIR sensors that work only for humans and not for pets etc. BTW I know the LDR in the circuit is connected wrong, I've taken care of that.http://www.ingenstech.com/projects/automatic-power-saver/

author: Jeroen3
author_rank: Super Contributor
timestamp: November 06, 2014, 03:21:56 pm
content: I think this all depends on the freshnell used.

author: ConKbot
author_rank: Super Contributor
timestamp: November 06, 2014, 05:22:43 pm
content: The reason most security PIR sensors are at waist height, is that they look out horizontally and upwards, so pets will be ignored. Position/aim the PIR with a correct lens so that it ignores stuff under ~1m tall. And tell the kids that they are out of luck unless they wave their arms up in the air.

author: con-f-use
author_rank: Unknown
timestamp: November 06, 2014, 06:16:29 pm
content: You can try to block the periphery of the sensor or point it higher.

author: wazzokk
author_rank: Contributor
timestamp: November 06, 2014, 07:46:06 pm
content: I have had some success tapeing off the lower part of the lens, trial and error on the outside then when you have it right tape the inside.A few PIRs actually have a moveable board inside, you never know your luck.Cheers Dave

author: Radhuvir_G
author_rank: Newbie
timestamp: November 11, 2014, 08:00:07 am
content: thanks for your suggestions friends will check it out ..

author: Vito_R
author_rank: Regular Contributor
timestamp: November 11, 2014, 08:07:43 am
content: There are many what we call Pet Immune detectors on the market. I've used Honeywell DualTec with good results in the past. Works up to 100 LB pets unless the cat or dog starts jumping on the tables or gets up high enough.DT7235TDUAL TEC Motion Sensor• Range: 35' x 40'• 100 lb. Animal Immunity• No adjustments to set• K-Band technology for better patterncontainment and pattern shaping
Automatic Rain Cover - Page 1
Forum section: electronics / projects

author: jagjeet k
author_rank: Newbie
timestamp: November 20, 2014, 05:55:08 am
content: I am trying to make this automatic rain cover system that extends a shade for my dog, when it is raining, but there is some electrode shown in the circuit and I am not sure if there are some specific sensors for detecting rains. Not sure if electrodes is even the right term for it.http://www.ingenstech.com/projects/automatic-rain-cover/
Automatic short circuit detection jig - Page 1
Forum section: electronics / projects

author: OM222O
author_rank: Frequent Contributor
timestamp: March 03, 2019, 08:18:07 pm
content: Hey guysI'm hand soldering 100 PCBs (all SMD parts) and they're quite complex (more than 50 parts). The problem I have is that often there are some shorts between a few pins of very fine pitch ICs as the combination of the stencil I have and the solder paste I use applies a bit too much paste.This requires a lot of probing to find the short and fix it (usually about 30mins or so from start to finish). I wanted to add some test pads to nets which are likely to be shorted around the board so I can use another PCB which has some pogo pins to find the shorts. I'm not sure what is the best circuit to use in order to identify the shorts between nets. one circuit which I through of was a 100uA current source (REF200) which is switched by a switch IC between nets and trying to look for that current on other nets using a 47k resistor and measuring the voltage on top of it (4.7 volts at 100uA) but I feel like I'm over complicating this alreadyis there a simple way you can think of to probe the nets vs each other?Also if you know of small pogo pins (preferably THT but smd would be fine as well) please put a link to them down below. thanks.

author: Pack34
author_rank: Frequent Contributor
timestamp: March 03, 2019, 10:03:43 pm
content: For something like that, I would either have an assembly house take care of it since you're doing 100 units.Otherwise, Adafruit has a tutorial for a pogo-pin style test setup. I would bring the power rails down and use a couple switches to test for continuity.

author: kony
author_rank: Regular Contributor
timestamp: March 03, 2019, 10:19:05 pm
content: If rework of TQFP/SSOP is taking you more than 30s per botched board, you are doing something very, very wrong. Drown it in flux, dragsolder it, wick the excess, done.

author: OM222O
author_rank: Frequent Contributor
timestamp: March 03, 2019, 10:48:24 pm
content: I have already bought the PCBs (no fiducials ) and parts (not on a reel) which was a very stupid mistake but one that I can't undo ...Also it's not the de soldering itself that takes long ... it's the detecting the shorts which is painful ... I had a few units where I had to take 2 to 3 chips out to find a short because it was literally under the IC and not visible. the nets are also complex so I can't easily tell which pin might be shorting to somewhere else. that's exactly why I'm trying to build a jig at the first placeI think I found an easier way though: I can use a micro and pull one of the nets high, then check the rest of the pins to see if they are also high, which means they are shorted. that way it'll be a lot faster and doesn't need fumbling around ... I'll watch the Adafruit video to see how they did it, thanks.
automatic shutter closing project - Page 1
Forum section: electronics / projects

author: Scat97
author_rank: Newbie
timestamp: August 07, 2018, 07:31:17 am
content: Hi,I was bored the other day, and decided to make a bypass switch for my shutter so that I can program my shutters to automatically open or close using an esp8266 (mainly so that I can shut it automatically just before the sun comes up). I did want the mechanical switch to stay operational though.I made a basic BT136 triac system coupled with a MOC3021 optocoupler. This works just fine, however when I try to use the mechanical switch (which is in parallel to the triac) the triac seems to break and stays turned on... I have put in a snubber circuit consisting of a 39 ohm resistor and a 0.1uF capacitor over each triac, as the motor might act as an inductor.Even though this started as a easy project because I was bored, I am starting to get quite annoyed that this isnt working properly, and I cannot understand why. Hope someone here can shed some light on the problem I am experiencing.
Automatic solar led - Page 1
Forum section: electronics / projects

author: digik
author_rank: Regular Contributor
timestamp: December 23, 2018, 07:52:01 pm
content: Hi guys,can someone tell me why this suckerdoesn't work at all?My solar panel is a 5.5V one to charge a 3.6V Ni-Mh battery and I have a 3.2V led attached. Every time i cover the solar panel the led is very dim, it goes bright only if I short the panel (of course). It seems that I don't have enough current flow, Why? I have already made other circuits exactly like this with other led and it always worked, why this time didn't? Are there other ways to do with less parts possible? The transistor is a BC 557

author: Efe_114
author_rank: Contributor
timestamp: December 23, 2018, 08:18:07 pm
content: i think its because of the high resistance of the solar panel when it is on shade. when solar panel is in shade its resistance increases and enough base-emitter current cannot flow. you can try replacing the single transistor with a PNP darlington pair so it can function with a lower base-emitter current(higher gain allows that).maybe you can try removing/decreasing the 10k resistor connected to transistor base to increase the base-emitter current, thus the collector-emitter current increases

author: digik
author_rank: Regular Contributor
timestamp: December 23, 2018, 08:36:35 pm
content: Thank you very much Efe_114, that was what I thought. I've already tried to remove the base resistor and the leds became slightly more bright but not enough. Will the darlington pair have some disadvantages (current consumption and/or voltage drops)? Can I connect them straight together without any additional resistor?I've also tried the schematic that bigclive did in this video and it did't work either. Also it seems that the diode is connected in the wrong direction, but in his video everything worked perfectly.

author: Zero999
author_rank: Super Contributor
timestamp: December 23, 2018, 09:08:57 pm
content: A MOSFET would be better.I suspect the solar panel has a built-in diode. Move the 10k resistor to across the panel.

author: Efe_114
author_rank: Contributor
timestamp: December 23, 2018, 09:19:40 pm
content: I agree with Zero999 about the MOSFET idea since MOSFETs have so big gain that might work well. You can (probably) keep the resistor if you use a darlington pair. Have a nice day and i hope it works soon!

author: Zero999
author_rank: Super Contributor
timestamp: December 24, 2018, 07:16:04 pm
content: If the solar cell has a diode, there will be no leakage current. Try this.
Automatic speedometer for paper airplanes - Page 1
Forum section: electronics / projects

author: Ricardodavinci
author_rank: Contributor
timestamp: January 07, 2014, 11:49:51 pm
content: Hello every one!I'm designing an unusual project, and need some help! I used an Arduino and a couple of IR barriers to count the time for toy drag racing cars. Now I'm about to use the same setup to calculate the average speed of an paper airplane. The problem is when you throw an paper plain, it is not so easy to hit the IR barrier to trig the timer to start. More dificult to make the plane pass the second one....How would you design a wide, tall and narrow barrier to trig the start and stop signal? I though about IR, PIR, ultra sonic and laser. But I'm sure some out there have a nice idea! Check out the simple drawing to get an idea of my setup.

author: Rufus
author_rank: Super Contributor
timestamp: January 08, 2014, 12:03:13 am
content: It used to be done by bouncing a beam between mirrors in a zig-zag pattern. Difficult to align and to keep the mirrors clean enough. Nowadays maybe scanning laser beams is more practical.The requirement is similar to that of safety barriers on machinery. Searching for "light curtain" may give you some ideas or clues.

author: TheCommonCathode
author_rank: Contributor
timestamp: January 08, 2014, 12:05:21 am
content: Oh, so your using like a Chronograph?Sent from my iPad usingTapatalk

author: vk6zgo
author_rank: Super Contributor
timestamp: January 08, 2014, 01:46:43 am
content: If you are using the paper plane indoors,paint two lines on the floor.If you have a nice high ceiling,mount one TV camera facing down.Watch the monitor,start a stopwatch when the plane crosses the first line,stop it when it passes the second,Calculate the average speed.If you have a low ceiling you will need two cameras,to avoid error.This method worked well for the WA Police catching speeders in the 1970s,using a cop in a 'plane instead of the TV camera, & 0.5km spaced lines on the road.For a while,this was popularly known as "Pigs in Space'!(No offence intended to any Police Officers present)Ok,this isn't automatic,but you could probably analyse the video signal & do the calculation automatically.
Automatic Switch - Page 1
Forum section: electronics / projects

author: Monomo
author_rank: Newbie
timestamp: March 30, 2014, 03:16:25 pm
content: I want to build a solar powered charging station for mobilphones.For a project I need a automatic switch to turn on and off a DC/DC converter (for power saving).I came up with the circuit in the attachment.It should switch on the DC/DC converter when a load is connected.When the load is disconnected the voltage rise an the DC/DC should switches off again.Is this circuit working (I haven't try it jet)?Is there any improvement for this circuit?Or is anyone knowing a better circuit for this task?
Automatic transformer tap switcher for bench power supply - Page 1
Forum section: electronics / projects

author: diydidi
author_rank: Contributor
timestamp: February 24, 2016, 06:04:12 am
content: HI Guys.I'm in the process of building a variable bench power supply. 0-50V @5A.I have wound the transformer secondary for 0-6-12-22-44 taps. By doing this I can geep the dissipation through the output transistors to a minimum.I would like to build a circuit that can automatically switch the taps in and out as I advance the voltage pot etc.Obviously only one relay should be on at any given time, otherwise two of the taps may be shorted. BOOM!!I will have to power whatever circuit and reference voltage from one of these taps as I don't have space for another auxilary power supply to power this circuit too. I was thinking 4 comparators driving npn transistors, switching 4 relays in and out.Any ideas? Anyone build something similar before?

author: Ian.M
author_rank: Super Contributor
timestamp: February 24, 2016, 08:13:00 am
content: To avoid the risk of short circuit, use 2 relays, one DPDT and the other SPDT. The DPDT relay would have its fixed contacts connected to all four taps so it chooses between 6 or 12 on one pole, and 22 or 44 on the other. The SPDT relay would choose between the high and low range outputs from the DPDT relay's moving contacts. Implement the drive logic with a quad comparator providing three output signals for the switching points.Call the three switching point outputs A,B,C in order of increasing voltage. B drives the SPDT relay. The DPDT relay is driven by NAND(NAND(A,NOT(B)),NOT(C)) which can be done with a quad NAND logic chip. Both relays will need driver transistors. You will want to set enough hysteresis for the comparators so it doesn't jitter between taps.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 24, 2016, 08:56:37 am
content: Asked thesame questionback in 2012 and still no answers eh?Here is how it is usually done when your intent is load regulation.If you want wide range like 0-50V the tap spacings should be equally spaced.It should also be possible to use 4 smaller transformers and change the wiring to series/parallel.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 24, 2016, 03:52:03 pm
content: One could use 2 relays to choose between the 0,6 and 12 V tap for the one end, and a second relay to choose between the 22 V and 44 V tap for the other side. So you have the choice of 10, 16, 22, 32, 38 and 44 Volts. If you really want, you could also enable the 12 V tap for the other side with an additional relay, to get choices of 6 V and 12 V, but I don't think this might be worth the extra relays. For control of the relays you could use comparators and some logic or alternatively a small µC.The µC could also do other tasks and maybe offer some protection against to much switching of the relays, which might damage the transformer and relays. in case of a heavily variable load. The mechanical relays are not fast anyway, so a few more ms from the µC do not really matter.
Automatically turn on tablet in a box when opening the box - Page 1
Forum section: electronics / projects

author: Medmeccy
author_rank: Newbie
timestamp: September 16, 2019, 12:44:36 pm
content: Hello everybody,unfortunately I am stuck in a project and would be happy for help!In the project, a tablet is to be integrated in the lid of a box / case. On the tablet is the instruction manual of the project. How can I open / switch on the tablet automatically when the box is opened? It would be best if there was a ready solution for it.Thanks in advance!Medmeccy

author: ledtester
author_rank: Super Contributor
timestamp: September 16, 2019, 04:32:23 pm
content: Do you need to use a specific kind of tablet (Android / IOS / Windows / ...)?Will the tablet be plugged in or be running on batteries?I doubt you will find an hardware/electronics solution for this. All of the tablets I've used are designed to be turned on by physically pressing a button. The most likely approach will be a software one in which the tablet is put into deep sleep and is awoken by a motion event - like phones are:https://lifehacker.com/how-android-doze-works-and-how-to-tweak-it-to-save-you-1785921957But this means that the tablet is always powered even if it will consume very little power most of the time.Note that even if you find a solution to automatically powering on the tablet it will take time (like several seconds) for it to boot and start running your application.

author: FreddieChopin
author_rank: Regular Contributor
timestamp: September 16, 2019, 05:05:50 pm
content: My clouded memory recalls that old Nexus 7 tablet (2012 model) probably had a reed switch and could activate when case was opened... but I'm not 100% sure about that.

author: oPossum
author_rank: Super Contributor
timestamp: September 16, 2019, 06:33:36 pm
content: iPads have a hall sensor for the smart cover/case. On my 2nd gen iPad mini it is just to the right of the home button. So all you would need is a strategically placed magnet.

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 16, 2019, 06:47:19 pm
content: If it's an iPad you could look at the suggestion above. If it's an Android tablet you could use any USB keyboard. Android will recognize and use keyboards and mice connected through USB.