hybridfree/eevblog-posts huggingface dataset:
IDC vs Crimp Connectors: Reliability, Robustness? - Page 1
Forum section: electronics / projects

author: Chendy
author_rank: Contributor
timestamp: September 24, 2019, 09:27:20 am
content: HelloWhats better in terms of Reliability, robustness?- for an internal wiring of an multiple PCB board, low power.- connector will be installed once, not repeatedly connected and reconnected.- the relative bending issues of IDC doesn't matter- I don't have space issues, so the relative larger size of a standard 2.54mm IDC matters not.I think I understanding the other aspects, costs, benefit of having option of intertwined grounds of IDCs.Are IDCs still used in a scenario like this?Cheers

author: TomS_
author_rank: Frequent Contributor
timestamp: September 24, 2019, 02:53:30 pm
content: What environmental factors do you have to consider? Vibration? Temperature? Moisture? etcIDC is still used a lot in modern products with no issues.

author: DaJMasta
author_rank: Super Contributor
timestamp: September 24, 2019, 03:17:47 pm
content: Sounds like IDCs are a no brainer. Why crimp a dozen or more contacts and put them in a housing when you can snap one on a ribbon and do a fine enough job. Modern products tend to be made to avoid cables as much as possible, since it's often one of the more expensive assembly parts (time and parts), but they're still used when needed. Crimps can be better for mechanical stresses, larger wiring, etc... but it doesn't sound like any of your requirements would rule out IDC.

author: MosherIV
author_rank: Super Contributor
timestamp: September 25, 2019, 07:05:42 am
content: HiI agree with the questions Toms_ asked.If the application has vibration or harsh environment then you have to go crimp and housing.Choice of connector is critical.I have worked in Military and automotive environment and both require the toughest connectors/connections, so only crimp connectors are used. NO solder joints on wires.It all depends on the enviroment your applicatiin has to work in.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 25, 2019, 08:05:34 am
content: Ribbon cables, you don't have much choice. Power connections, can be done that way but really shouldn't, and you'll probably encounter something gone bad, some day.Failure rates like one in a thousand kind of thing, or decades aging kind of thing, I think?Tim

author: Chendy
author_rank: Contributor
timestamp: September 26, 2019, 02:34:08 pm
content: @ TomS_"What environmental factors do you have to consider? Vibration? Temperature? Moisture? etc"Nothing demanding. static no vibration, normal room temperature, normal room moisture levels... sounds like IDC is the way to go
Identify cap type by dielectric loss? - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: August 27, 2021, 02:40:53 am
content: I have a bag of 100nF 630V and 220nF 450V caps that I was told are polypropylene. Is there any way to verify this by measuring the dielectric loss or some other way?

author: TimFox
author_rank: Super Contributor
timestamp: August 27, 2021, 02:54:48 am
content: The two likely dielectrics in that package are polypropylene and polyester (Mylar).At 1 kHz, polypropylene will typically haveQvalues of roughly 1000, but polyester will typically be between 100 and 200.A simple LCR meter such as the DE-5000 will be more than adequate for this measurement, or an old-fashioned capacitance bridge.
Idea: Alternative Way of Quick, Cheap and Easy Product Enclosure Supplier - Page 1
Forum section: electronics / projects

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 24, 2012, 08:26:28 am
content: having dismayed with the availability of plastic enclosure, local or international. too much price for a simple thing in ebay and not getting respond from some custom/pre made enclosure maker site... so.1) goto nearest supermarket.2) find consumer's electronics section3) find the enclosure that fit your size and price (dont read the manual, just look at the item)4) if you cant find, goto another supermarket.here are the example...1) some extra free components next to each enclosure (leds, connectors, battery tabs and some miscellanoues premade pcb)2) just around $1-2 each, not $10-$50 in ebay and no need international shipping fee.3) when run out, can run quickly back to the supermarket to get the stock.4) the black enclosures on top are the legit for ee project i got from our small ee shop here. limited choice.no need international order stereotype. except just for hobby use and poor man's method
IDEA: DIY Ringlight for video shoots. - Page 1
Forum section: electronics / projects

author: Jackster
author_rank: Frequent Contributor
timestamp: March 14, 2013, 11:19:25 pm
content: Hi all.I am thinking about making a ring light to add to my camera when making videos at conventions.WTF is a ring light?Here are some photos,The idea is that the light is evenly spread from the camera at what you are shooting.So what I need is a load of LEDs and to be able to dim them. Also going to need to run off a 12v Li-Ion battery pack.Just wondering what would be the best way to do this, the dimming part.Think we are looking at about 200 LEDs.Thanks guys!

author: EEVblog
author_rank: Unknown
timestamp: March 14, 2013, 11:22:01 pm
content: Why not just buy a commercial one?I know it's not as fun, but...Take a look at the Elector ring light project I reflow soldered a while back. It's micro based, but you don't have to do that. Just look at datasheets for various LED driver chips and they'll have app circuits.Dave.

author: Jackster
author_rank: Frequent Contributor
timestamp: March 14, 2013, 11:24:08 pm
content: Quote from: EEVblog on March 14, 2013, 11:22:01 pmLove making things.

author: smashedProton
author_rank: Frequent Contributor
timestamp: March 15, 2013, 03:45:01 am
content: Just use a quad opamp to make a square wave, take the integral, compare it to a threshold (brightness setting), and current amplify it to drive the leds array. Easy peasy

author: c4757p
author_rank: Super Contributor
timestamp: March 15, 2013, 03:51:57 am
content: So PWM? You can do that with a 555 as well - see Dave's video on that - and the circuit is easier to design, lay out, and build.

author: bustedcap
author_rank: Newbie
timestamp: March 16, 2013, 10:29:04 am
content: How would you get the colour balance correct? Some of the white LEDs give out a bluish tinge.

author: KuchateK
author_rank: Regular Contributor
timestamp: March 16, 2013, 01:07:18 pm
content: Some commercial units have mixed matrix of cool and warm white LEDs. They have independent control to set brightness for them separately. Better units have separate brightness and color knobs.
Idea for a project: Embedded device designed for standalone programming - Page 1
Forum section: electronics / projects

author: andrebarata
author_rank: Newbie
timestamp: August 18, 2011, 06:09:41 pm
content: Hello guys,Here's a suggestion for an open source hardware project:It seems that in our days all consumer embedded systems are designed to be programmed from a PC.Why cant we develop a handheld embedded device designed for being programmable from within, as standalone?I know we can use a regular laptop for software development, but it just doesn't seem the same as some portable PC's back in the 80's like the ZX Spectrum for example:So here's the idea... a cheap embedded system... designed with a open source IDE/compiler to build executables for the machine itself, probably a small querty keyboard in it, some sort of display or just vga/hdmi output.and why not a expansion socket, designed to be completely open and versatile like the arduino IOs.What do you think?André Barata

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 19, 2011, 01:10:41 am
content: What price range are you looking at? Android tablets start at about $100.
Idea for portable power supply for TS100 soldering iron - Page 1
Forum section: electronics / projects

author: ealex
author_rank: Frequent Contributor
timestamp: August 16, 2018, 02:05:56 pm
content: Hello guys,After trying to figure out how can an electric pushbike charger work with just an LM358 in the secondary and finding these app. notes:https://www.fairchildsemi.com/application-notes/AN/AN-4138.pdfpage 11 and 12,https://www.onsemi.com/pub/Collateral/NCS1002-D.PDFandhttps://media.monolithicpower.com/document/MP26085_r1.02.pdf, I thought I can use the same thing to charge a 4-5S Li pack, power the TS100 and have a sort of UPS that will maintain the power output when there is no mains ( assuming the battery has enough charge ).Warning - this is not my domain so i'll use the wrong termsI've modeled the schematic from AN-4138 in ltspice (draft4.asc, attached):A short walktrough, from left to right:- V1 is a 2.5 reference (TL431 that's already in a SMPS)- V2 is a power supply for the op-amps, aux winding or main winding,TBD- B1, R11 and D3 are used to simulate main winding: feedback gain, internal resistance and D3 ensures that the main winding can only source current- B1's variation rule ensures that it will decrease output voltage with increasing input voltage and it won't try going negative, just like a TL431 feedback would work- R1 is the current sense resistor- R2 and R3 form the feedback voltage divider- U1 and it's associated components form the voltage feedback loop, it will try to satisfy V(REF) = V(MAIN)*R3/(R2+R3)- U2 is the current limit loop: V(ISNS) is negative for the op-amp, so U2 will output a voltage as long as the voltage at it's negative input tries to go bellow 0 - this does not look right, i'll have to build it and see- D1 and D2 are OR'in the outputs => whoever has the higher output voltage takes over the control loop- C2 is there to simulate a battery, there is an initial condition that it starts from 12V on simulation start-up- M1, V3 and R5 simulate the load, that needs to be attached before battery charger current sense, so it's kept out of the current regulation loopHow I've imagined it should work:1. when there is no load attached: U1 and U2 will act as a CC/CV charger until the battery voltage reaches the set point. I need to check if the current will go to zero, so the battery is not trickle charged. I think the set point should be under 4.2V per cell.2. when the load is attached: V(MAIN) drops because of the extra load, U1 compensates for that by lowering it's output voltage and the battery will provide some extra current via R1 until output voltage settles.3. when the primary is not powered, the battery will supply the load via R1, while U1, U2, the voltage reference and the optocoupler will draw some parasitic power if i won't use an extra winding as shown in AN-4138.Do you thing this will work ?I have an old / simple SMPS ripped out of a scanner that can be used for testing: tl431 secondary feedback, no extra overvoltage protection, etc.
Idea for portable sound - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: June 19, 2014, 10:34:31 pm
content: I was looking to buy portable speakers for my laptop so I can enhance the weak sound. My ideal would be:1) round or square and fits in the palm of your hand like a cricket ball2) you twist it off and it becomes two pieces, stereo speakers3) connects via USB and/or bluetooth to your laptop but only one wire, not cool to have to deal with two wires getting tangled up and difficult to fold back when you want to close it4) very good quality soundApparently, by reading the reviews on Amazon, such a product does not yet exist.

author: SirNick
author_rank: Frequent Contributor
timestamp: June 19, 2014, 10:43:50 pm
content: Quote from: akis on June 19, 2014, 10:34:31 pmPick one.

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 19, 2014, 11:22:48 pm
content: Quote from: akis on June 19, 2014, 10:34:31 pmIt takes physical SIZE to move air at low frequencies. As SirNick indicated, your requirements #1 and #4 are mutually exclusive.And don't hold your breath. That's one of the laws of acoustic physics that I don't expect we will be able to break.
Idea:  Low voltage crowbar - Page 1
Forum section: electronics / projects

author: FrankenPC
author_rank: Unknown
timestamp: June 07, 2014, 04:36:28 pm
content: I have a current limited bench supply and I would like to make an external variable voltage crowbar device for it. There are a ton of crowbar circuits out there based on voltage shunt IC's and SCR/thyristor/triac combos. But they all have a relatively high Vref demand of at least 2.5V.I would like to go down into the < 1V range if possible. Do I need a smart crowbar? For instance, how about a battery powered microcontroller with ADC input triggering a SCR? It seems to me that the floating gnd on the power supply would create a dangerous environment for anything controlling the SCR.Looking for suggestions/warnings.A good page with the most common crowbar variants:http://axotron.se/index_en.php?page=26

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 07, 2014, 05:37:06 pm
content: Those circuits are good, with one mod: I would include hysteresis, at least on the "fancy" transistor'd versions. 10mV back to Vref or the "anode" (whichever is easiest and works correctly) would be enough. That way you don't risk malfunctions on slowly rising supplies.TLV431 is 1.24V, so there's that. There are chips of various flavors with internal references from 100 to 800mV, though they obviously(?) require additional voltage to function.You need at least 0.8V to guarantee SCR turn-on, and about as much to maintain current through it as well.A MOSFET can pull down lower, but requires positive gate voltage. Or if you're lucky enough to find a depletion mode device or JFET that big, but...beats me if such is available. Even so, you would then need a substantial negative supply to provide reverse bias when it's supposed to be off.If you can have a bias supply for it, it'll do well. The purpose of a crowbar is to shunt *excess* power, which implies you have an excess available somewhere..Tim

author: FrankenPC
author_rank: Unknown
timestamp: June 07, 2014, 09:15:54 pm
content: Quote from: T3sl4co1l on June 07, 2014, 05:37:06 pmThanks for the tips. Actually, in real life scenario's, 1.25V is low enough.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 07, 2014, 09:34:45 pm
content: It would be nice, in theory at least, to have some sort of solution for protecting 1V core rails, I suppose. Even just 1.8-3.3 (say, for higher speed / performance embedded) is annoying because there's no such thing as a zener TVS under 5V (or rather, they don't make them, because they're too soft -- too leaky at a useful voltage, or not sharp enough to do a useful job).Although in practice, I suppose deep inner bits like Vcore (0.9-1.8V at mA to 100A+) are usually fairly well isolated from the great outdoors through one or more stages of SMPS. Still, it would be hard to protect the rail against a faulty SMPS (suppose the high-side MOSFET fails shorted for some reason).It's a good question, worthy of good solutions.Tim
Idea needed for 2:1 analogue multiplexer - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: August 10, 2014, 06:52:02 pm
content: I want something like the DG409 but without the second channel (less 5 pins) and only 2:1 so another 3 pins off. That would be a small IC (8 pins) with:V+V-GNDS1S2DAWhat the DG409 (and many others) offer is switching based on logic levels logic 0=0V and logic 1=2.4V or greater. Also capable of handling +/-22V (hence the V- pin).I do not think such a small IC exists so maybe it can be done from discreet parts, but my attempt at using jFETs as the switching devices requires switching voltages of V+ for "logic 1" and V- for logic "0" so a few more components needed there too.PS:forgot to add: a relay would do but is noisy and needs a lot of drive, maybe a reed relay (still requires drive), two SSRs (6 pins each and a few resistors).

author: fcb
author_rank: Super Contributor
timestamp: August 10, 2014, 06:55:32 pm
content: MAX325?

author: akis
author_rank: Frequent Contributor
timestamp: August 10, 2014, 07:07:22 pm
content: Doh!DG419 is the one...Also MAX319 but much more expensive.Why could I not see those before?
IDEA REQUIRED - Measuring 0-800V AC voltage of varying frequency SYNC GENERATOR - Page 1
Forum section: electronics / projects

author: AndyChriss123
author_rank: Newbie
timestamp: April 23, 2022, 05:35:57 pm
content: Hello everyone and thank you for joining!I need some help if you are willing to spare a couple of minutes.. How would you go about measuring the voltage of a synchronous generator?It is rated for 800 V and that is all I know as it is missing the plate on it, oops china...I built a simple sensor that I'm going to test soon. I use a transformer 800-24 followed by a full bridge rectifier with a cap and a voltage divider to get the 0-10VDC that I need for the PLC Analog Input but I have doubts about how well this is going to work.. I never had to measure voltages with greatly varying frequencies before so I expect a huge dead-zone as it will mostly operate in the 400(v) zone. The transformer is rated for 50-60 (Hz) but in this case the sensor will have to operate mostly in the 20-40 (Hz) range.I don't really care about resolution or complexity (throw whatever at me, easy or hard), i just need the solution to be somewhat reliable a.i. not to have a lot of deadzone or blow up too often.Soo... How would you go about this?Transformerless ADC or a Voltage to Frequency converter or some other transformerless solution?Thank you very much for the time and experience!

author: moffy
author_rank: Super Contributor
timestamp: April 23, 2022, 06:52:20 pm
content: Use some resistors to divide the voltage, assuming 400-800V RMS @ 20-40Hz, and a multimeter on AC range? Or is there more to what you want to do?

author: AndyChriss123
author_rank: Newbie
timestamp: April 23, 2022, 07:05:43 pm
content: The multimeter part I don't really get it as I'm interested in continuous measurements using a PLC instead of visual readout of the multimeter's screen.And a simple voltage divider without the transformer as I understand you are suggesting was the first solution I thought of but eliminating any kind of insulation (transformer, optocoupler etc) from the design wouldn't be a serious hazard?Thank you for taking the time to post a suggestion!To be honest there are many things that would work in my case as I don't really care about resolution. I'm mostly curious about what is the most efficient/smartest way to do this

author: moffy
author_rank: Super Contributor
timestamp: April 23, 2022, 11:54:45 pm
content: Well if you want the PLC to do something with it and counting the frequency of pulses is accurate enough, a voltage to frequency converter just requires a single optocoupler for signal isolation, as well as its own isolated supply. Use a resistive divider to get the voltage down to reasonable levels, be careful not to exceed the resistor breakdown voltage, use multiple in series if need be, then feed the divided voltage into a precision rectifier which you then filter before feeding it into your VtoF converter and out through a suitable optocoupler.
Idea to eliminate wirewound resistors inductance - Page 1
Forum section: electronics / projects

author: 001
author_rank: Super Contributor
timestamp: October 24, 2019, 01:48:14 pm
content: HiCan I compensate inductance if I connect center tapered wirewound resistor as shown?Can I use steel bolt to fit it?Moderator note: please upload a sensible sized picture!

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: October 24, 2019, 03:25:06 pm
content: I'm sorry but your picture is way to small. could you provide us with a bigger one so that I can see the molecular structure of the paper even better?Also, I'm not quite sure what you mean with the steel bolt. could you explain that more precisely?

author: 001
author_rank: Super Contributor
timestamp: October 24, 2019, 03:31:11 pm
content: the idea is to short outer legs with wire to parallel both windings out of phase

author: james_s
author_rank: Super Contributor
timestamp: October 24, 2019, 04:01:51 pm
content: Don't they already make non inductive wirewound resistors that have two elements wound in opposite directions?

author: pwlps
author_rank: Frequent Contributor
timestamp: October 24, 2019, 05:04:15 pm
content: To suppress inductance you would need a perfect inductive coupling between the two halfs (the idea is to keep the total magnetic flux as small as possible). So for example it will work if the two halfs are wound on the same ferrite rod like in a transformer, otherwise if there is no ferrite the coupling will be poor unless the length of the coil is much smaller than its diameter.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: October 24, 2019, 05:45:16 pm
content: Quote from: james_s on October 24, 2019, 04:01:51 pmYes.https://en.wikipedia.org/wiki/Ayrton%E2%80%93Perry_windingI frequently use Ohmite brand A-P wound noninductive precision resistors for current monitoring. There is usually more inductance in the wiring to it than in the resistor itself.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 24, 2019, 07:23:18 pm
content: Yes, but only slightly. The coupling factor between the halves of the resistor will be small, about 0.1, so the reduction compared to a pair of shorter resistors in parallel (without the adjacent arrangement) will be on par, about 10%.Use a noninductive design.On a related note, you can equalize it by putting an R+C in parallel, where the R's are equal and C = L / R^2. But this shifts the current from the main resistor to the equalizing resistor at high frequency, so if you need to handle a lot of power at any frequency, yeah no... Can be acceptable for low frequencies with rich harmonics (where the high frequency power is fairly small).Tim

author: floobydust
author_rank: Super Contributor
timestamp: October 24, 2019, 08:34:18 pm
content: It's a messy issue as the wirewounds typically have steel end-caps and leads.I think it's mostly air-space on a solenoid form, so none of that should saturate.But I get weird readings with an L meter from 5-25W parts and never tracked that down.I useplate resistors"low inductance" for audio power amp emitter resistors.Non-inductive parts are very rare and expensive.
Ideal diode (mosfet) rectifier bridge - Page 1
Forum section: electronics / projects

author: not1xor1
author_rank: Frequent Contributor
timestamp: February 05, 2017, 03:06:52 pm
content: while comparing various solutions via LTSpice I realized that the LT4320 model is probably wrong as the negative node mosfets do not behave as expected (see the screenshot below).Isn't that wrong?
Ideal Diode circuit - Page 1
Forum section: electronics / projects

author: Infrared_Fred
author_rank: Regular Contributor
timestamp: March 04, 2021, 08:43:42 pm
content: In thissimulation, the circuit with the LM324 op-amp (rightmost)seems to be working as an ideal diode(?). I am interested in building a similar circuit for an AC rectifier and I was looking for comments/critiques, on the design or any other suggestions. BTW the ultimate circuit would be in a bridge rectifier circuit but that was a bit too complicated to draw on that simulator. Also there is theLT4320but for cost considerations, I would as soon go with a plain bridge rectifier and take the power loss. Input specs: 40Vrms 60Hz 6A current limit of the transformer output:5A 15mF capacitance ~48V out. Thank you!

author: Ian.M
author_rank: Super Contributor
timestamp: March 04, 2021, 09:24:42 pm
content: 4 bad connections . . . . (all around the LM324)Falstad is NOT a full SPICE simulator and if abused frequently provides misleading results.Do yourself a favor and re-draw it without the crud in parallel on the left, in a serious SPICE package, preferably a popular one that's free (to use), e.g.LTspice, then if it *still* doesn't make sense, attach the sim files (but *NOT* generated result files) here.Hint: In LTspice, putting the following SPICE command on your schematic:Code:.model Dideal D(Ron=10n Roff=.1G Vfwd=0) ;Ideal diodegives you an almost perfectly ideal behavioral diode model, that you can invoke by placing Diodes and editing their value toDidealso you can construct a bridge rectifier with three of the Dideal diodes and only ONE of the more complex read-world 'ideal' diode circuit you are trying to simulate.

author: Infrared_Fred
author_rank: Regular Contributor
timestamp: March 06, 2021, 03:09:24 pm
content: Okay, I will do that. Thank you!
Ideal diode with mosfet not working - Page 1
Forum section: electronics / projects

author: german77
author_rank: Regular Contributor
timestamp: April 06, 2018, 04:55:53 pm
content: I made a circuit with an ideal diode to protect from monkeys faults. It must handle up to 6A continuous. It works fine in the right direction, but if I put power in the wrong direction(not polarity) it stills lets current trough but at a lower voltage 15.2v.I make sure that everything is connected properly, even tested each component to see if it's fine. I measured the voltage at the gate and source and they are both 24v exactly. In theory for me that's well powered off as gs voltage it's around -2v.To make things more interesting the 15.2v are as solid as a rock, consistent between different components and values. Tested up to 1.3A with not significant drop on the voltage until the magic smoke scapes, the mosfet heats up as is taking 11w.If someone can tell me what I did wrong, I would appreciate it very much.

author: german77
author_rank: Regular Contributor
timestamp: April 06, 2018, 05:50:17 pm
content: Found the source of the problem. I removed the mosfet from the circuit. And the 15.2v were still present. Only t16 is connected to de input, so it must be the source of the problem, but I still not know what's going on. The transistor works like a diode even confirmed the 0.7v and open voltages with a multimeter. The break down voltage must be around 80v.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 06, 2018, 06:09:46 pm
content: B-E breakdown is only about 7V. This circuit only works at low voltages.Here's a faster diode, but it's intended for common-ground applications. You'll need a floating 5V supply (maybe a DC-DC converter or charge pump?) to power it:This uses inverted BJTs so the breakdown voltage can be high, unfortunately the gain is low, needing more parts to get good performance.Tim

author: german77
author_rank: Regular Contributor
timestamp: April 07, 2018, 12:36:58 am
content: It's not easier to help the transistor with an extra diode? It will block the reverse current, be low cost and have almost no difference in functionality.The other transistor shouldn't need that diode because the mosfet will be on. Please correct me if I'm wrong.Edit: Works fantastic, with no downsides. Thank you for finding the problem, I should be more careful reading those datasheets.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 07, 2018, 02:45:17 pm
content: It works in the reverse direction, sure... now try reversing it.You need matched diodes to do that, so the offset is still ~0V.A zener from MOSFET gate to source is also a good idea, so as not to exceed Vgs(max).Tim

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 07, 2018, 03:30:49 pm
content: Note that Linear makes pretty nice ideal diode controllers that would make your design fool-proof, such as the LT4351 or even the LT4320 which is a full-bridge controller.
Ideal replacement for LEDs in current-driven strings - Page 1
Forum section: electronics / projects

author: mattj
author_rank: Newbie
timestamp: November 21, 2014, 10:38:09 pm
content: Hi all,Just to give some context, I'm a hobbyist electrical engineer but with a background in industrial-style electrics (specifically theatre & events). My experience is mainly with digital electronics (and the high-power AC stuff) but this is much more of an analog problem!I've recently taken on doing some repair of some china-sourced LED fixtures -similar to these.Generally all the drive side is fairly straightforward repair - but I'm not sure what the best approach is on the LEDs. I cannot source replacement diodes - it would have to be an exact match with the others on the board which are obscure chinese parts, as otherwise it would throw off colour-mixing, so it's safer just to leave these dead - but being in a series string, I can't just bridge over the LED (at least I think not!).There's two basic architecture:V1: 24V supply fed into LM317 configured as fixed current source - for one particular colour, ~450ma. A variable number of LEDs (depending on their forward voltage, to maximize string length) then a low-side MOSFET doing 1khz PWM dimming.V2: 48V supply fed straight into the string - different strings have a different number of LEDs. Low-side buck converter acting as a current source (sink?), again in this case configured for ~450ma (although there are a total of 12 converters, one per string, at varying currents). This is using a clone of a Microchip HV9910 as the controller.V2 is the trickiest - in some cases, a single converter powers two parallel strings - and I only want to bypass a dead LED on one side of the string.So I have four situations that I want to bypass:S1: Dead LED on single string powered by high-side LM317.S2: Dead LED on single string powered by low-side HV9910.S3: Dead LED on one of two parallel string powered by a single low-side HV9910.S4: Dead LEDs on both of two parallel strings powered by a single low-side HV9910.Probably over-thinking this but I'm really not sure what to do for these. For S1/S2 I believe I can get away with a power resistor - but not sure of the current-voltage characteristic once they are dimmed - would this cause this string to react very differently?I also considered using a plain diode with the approximate right voltage drop - easy enough for Red (1.75V) although getting the power rating desired isn't that easy and from my search a little more difficult for white & blue.I can't do anything active or too complex as this has to be bodged on the existing PCB, into about 10mm max height (preferably less).Sorry for the long post, but hopefully someone has some ideas - I've been thinking about it too long I'm worried I'm missing the easy options!Thanks,Matt
Idealizing a 3-phase current and voltage reader - Page 1
Forum section: electronics / projects

author: sata
author_rank: Newbie
timestamp: August 09, 2022, 12:41:41 am
content: Greetings all,I have a 3-phase instalation at home, with 6kw of PV installed.I will be building an energy meter that measures intake and outake current.The point is if the PV is producing more than 1000w of power, to turn on a Heat Pump.Once the intake is over 1000w, it will power it off.My first concern is:-Are there purchasable modules that do this kind of work, so that i can purchase them and just connect them no a PIC and read data and do the math with it?Or should i build a module for it from scratch?What i saw with a bit of googling was some zero cross detectors and some ZMPT101B modules for voltage readings. I could use 3 of them with a timer to measure voltage on ADC ( after ZCD, 5ms for first phase, 11.666ms for second, 18.333ms for third phase)Measure current is a bit more tricky, if i'm powering an inductive/capacitive load the current will not be in fase with voltage. Perhaps sample current several times and do an average?Set a delay so that the HP doesn't get enabled/disabled continuously, something like 1 hour?My second concern is:-The heap pump is single phase. Yep i know... now the PV system injects on the 3 phases and only one third is used by it.Could i convert the 3 phases to a single for the HP with something like a Open-Delta transformer? Would that be efficient?One last question:Arduinos shields/modules are an quick, cheap and easy way to add hardware to a microprocessor as we need.Does Microchip have something remotely close to it?That's about it. I would love to hear some design suggestions on such a build. Although i have a sketch of it in my head already (a few to be honest), i rather follow the opinion on more experienced folks.Any tip appreciated.Thanks,sata

author: Circlotron
author_rank: Super Contributor
timestamp: August 09, 2022, 01:45:47 am
content: Quote from: sata on August 09, 2022, 12:41:41 amShouldn't be a problem. I have 3-phase at home (unusual for a domestic installation where I live) and for a while I had solar on one phase and aircon on a different phase so there was power coming in on one and going out on the other and if the outgoing exceeded the incoming then the smart meter did not register any consumption. Might depend on exactly how your smart meter is configured though.

author: sata
author_rank: Newbie
timestamp: August 09, 2022, 06:52:17 pm
content: Quote from: Circlotron on August 09, 2022, 01:45:47 amWell that would solve a big problem for me then, will have to test it as soon as possible!
Ideas for a 30mm CRT project - Page 1
Forum section: electronics / projects

author: Aleksolder
author_rank: Contributor
timestamp: October 24, 2017, 02:35:42 pm
content: I have a Russian 3LO1I 30mm CRT, and four Orzep IV-21 vacuum flourescent display tubes (8 numeric digits each). Lovely components. Aside from the usual clocks, does anyone have ideas for what I could make with these items, collectively or separately?

author: oldway
author_rank: Super Contributor
timestamp: October 24, 2017, 06:54:18 pm
content: With the crt, you could make a component tester. ("octopus" curve tracer)...http://www.jammarcade.net/simple-component-tester-a-k-a-octopus-curve-tracer/

author: ruffy91
author_rank: Regular Contributor
timestamp: October 24, 2017, 07:41:08 pm
content: You could make a miniature retro arcade machine:http://tubetime.us/index.php/2014/05/10/asteroids-mini-arcade-machine/

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 24, 2017, 10:09:47 pm
content: That VFD looks like it's from a calculator, so you could just make that. A more interesting project would be a pocket frequency counter or precision DMM.

author: Aleksolder
author_rank: Contributor
timestamp: October 25, 2017, 01:01:22 am
content: Great ideas, fellas, thanks! I quite like the octopus, it aligns well with the culture of CRTs. Perhaps mod it to include reporting of values. The calculator idea made me laugh, it makes perfect sense, and would keep this gorgeous display in routine use.All ideas remain under consideration, more are welcome, I'll keep watching here.

author: james_s
author_rank: Super Contributor
timestamp: October 25, 2017, 06:55:40 pm
content: Quote from: ruffy91 on October 24, 2017, 07:41:08 pmI have Asteroids Deluxe running on a small FPGA driving a custom made vector monitor, you're welcome to all the source for that project if you decide to go that route. I think it would be hard to play it on such a tiny tube though, the CRT from a 5" portable B&W TV is just about perfect.

author: Aleksolder
author_rank: Contributor
timestamp: October 26, 2017, 01:07:58 am
content: When I was in high school, computers had just come to the school (PETs with a 20kg external 5 1/4" floppy drive), and I used to copy arcade games as a way of learning. Quite a lot of fun. 35 years later I'm still looking for excuses to make something!
ideas for a project - Page 1
Forum section: electronics / projects

author: robs24
author_rank: Newbie
timestamp: September 09, 2015, 11:56:26 pm
content: Hello, I have a project in mind but I don't quite know how to go about making it happen. I have a very small fan that I need to continuously turn on and off, for a Halloween thing. I am not the most experienced in electronic projects. I am hoping somebody could point me in the right direction on how to go about this.

author: hamster_nz
author_rank: Super Contributor
timestamp: September 10, 2015, 12:09:16 am
content: One man's very small fan is different to another... a common small fan is 25mm x 25mm x 7mm, and runs from 12V DC. Any chance of more info on the fan?How often and how long does the fan need to be switched off and on? Every second? Every hour?

author: robs24
author_rank: Newbie
timestamp: September 10, 2015, 02:51:04 am
content: Sorry about that, but yes something similar to the 25x7x7 fan. I would like to have it turn on and off every few seconds.

author: RJFreeman
author_rank: Regular Contributor
timestamp: September 10, 2015, 03:31:21 am
content: Quote from: robs24 on September 09, 2015, 11:56:26 pm555 timer

author: RJFreeman
author_rank: Regular Contributor
timestamp: September 10, 2015, 04:37:22 am
content: I would expect this sort of thing would probably do the trick:http://www.vellemanusa.com/products/view/?id=350686Manual herehttp://www.vellemanusa.com/downloads/0/minikits/manuals/manual_mk111.pdfOn time adjustable between 0.5 and 5 seconds, off time between 2.5 and 50 seconds (or vice versa, depending on how you wire up the relay) will hopefully cover your desired "few seconds", although you could also increase the value of trimpot RV2 if you wanted to increase the on time.

author: obiwanjacobi
author_rank: Super Contributor
timestamp: September 10, 2015, 06:40:10 am
content: Quote from: RJFreeman on September 10, 2015, 03:31:21 am... and a transistor/mosfet to witch the 12V fan.A couple of resistors and caps and you're all set.To give you an idea (from interweb):R2, R3 and C1 dictate the speed/time at which the output is on and off.You (probably) cannot drive the fan directly from the output. That is where the transistor comes in.
Ideas for battery power on/undervoltage indicator? - Page 1
Forum section: electronics / projects

author: Martinn
author_rank: Frequent Contributor
timestamp: April 19, 2023, 05:08:47 pm
content: Hi all,I like battery operated circuits. The problem with those however is that you should supervise the voltage somehow. Mostly I just have an LED plus resistor (e.g. 1k for a 9V battery), but that does not really help because the LED is still lit if the battery is almost completely dead.Useful range for alkaline cells is 1.6 down to 0.9 V, so 5.4 to 9.6 V.It would be nice to have an indicator that (as an example) is green above 6 V and red below.Current drain should not be much more than the 1 mA needed for the LED.Bonus:Bipolar supervision (+-9 V)Lower cell counts (2 or 3 cell)Components should be from the JLC basic libraryhttps://jlcpcb.com/parts/basic_partsas they are almost free of charge (I have almost all my designs built by JLC), except for a common anode/cathode dual color THT LED.Quick idea below, does not really feel super elegant.Abusing a TL431 perhaps?Ideas?- Martin
Ideas for mini (low) power sources? - Page 1
Forum section: electronics / projects

author: CyberWalker
author_rank: Contributor
timestamp: July 12, 2013, 07:08:57 pm
content: My greetings to the honorable members of EEVBlog!I just recently got asked to contribute into a project that involves the low powering of a wireless sensor network which will be all custom made and designed/built from the ground up. It involves a research product of hundreds of engineers, each one contributing on the respective field of their expertise.My part has to do with the research on low power electric sources (let it be wind turbines or photovoltaic cells, etc... maybe sth like geothermal) so I would like some links or advice for anything useful you may have in mind. :-)THANK YOU very much!!!

author: mariush
author_rank: Super Contributor
timestamp: July 12, 2013, 07:29:47 pm
content: Shahriar at The Signal Path recently did a very interesting video about energy harvesting ICs along with practical demonstrations:

author: Paul Price
author_rank: Super Contributor
timestamp: July 12, 2013, 07:32:11 pm
content: Each device you must work with will likely require a specialized device or circuit solution..be more specific when you know clearly what some of your exact goals are.

author: CyberWalker
author_rank: Contributor
timestamp: July 14, 2013, 08:52:08 am
content: Dear mariush and Paul Price, thank you very much for your quick replies! :-)@mariush : yes, I find this video very very useful, this is exactly the kind of information that I would need for that stage.@Paul Price : yes, I could be more specific if I knew the specs, but the project is being shaped (and will be shaped) until the very last day (two years project), so ANY relevant information available (like mariush's) can be accounted as most valuable right now!Again, thank you VERY VERY much!!!
Ideas for modify 5v current sensor output please. - Page 1
Forum section: electronics / projects

author: PeterPerkins
author_rank: Newbie
timestamp: December 13, 2016, 06:41:41 pm
content: Hi all.I have a generic 5v supply rail to rail 200A current sensor with a 2.5v = 0 amps output.0v=-100A and 5V = +100A standard stuff.The sensor output has a 220R resistor in the circuit inside the sensor.It feeds into a generic microcontroller adc input so probably has an input impedance of 10k or so.I want to reduce the sensitivity of the sensor so that I can electronically adjust the sensitivity to give between a say 0 and +50% current increase.Bypassing it with some of the current is not practicable.Using two simple 1k resistors tied to the sensor +5v and gnd rails and to the sensor output I can reduce the voltage swings and get and increase in current of around +30% .. All good so far.However I want to electronically control the modifying rail tied resistors to give say a 256 step change.Do you think spi digital pots can do the job?Any better ideas?Do I need op amp buffers to keep the impedance?Thanks for the ideas.

author: ajb
author_rank: Super Contributor
timestamp: December 13, 2016, 07:25:36 pm
content: Quote from: PeterPerkins on December 13, 2016, 06:41:41 pmSure, that's probably the way to go as long as your current sensor can operate safely at those current ranges and is capable of swinging it's output beyond 0V and +5V. Also watch that you don't violate the input range on whatever digipot you select.QuoteWhen the MCU samples that ADC channel, there's an input switch that connects the ADC's sampling capacitor to that input pin, and the capacitor will be charged/discharged via the total input impedance (both internal to the MCU and the output impedance of whatever circuitry is connected to the input). At the end of the sampling period, the input pin is disconnected and the ADC performs the conversion. If the sampling period is too short or the input impedance is too high, the cap won't wind up quite equal to the nominal input voltage, and the resulting ADC reading will be off. So there's a direct relationship between the impedance at the ADC input and the required sampling time to achieve a given accuracy. Increasing the sampling time can compensate for a higher impedance, but of course this increases the total conversion time, which may or may not be a problem. If you consult the MCU's datasheet, you should see some information on the ADC input characteristics, and if you're lucky they may even give you a formula for calculating the maximum input impedance for a given sample time/resolution.
Ideas for repurposing/repairing 50W LED Floodlight - Page 1
Forum section: electronics / projects

author: joystik
author_rank: Contributor
timestamp: July 08, 2019, 07:26:08 pm
content: Hi guys, hows it going?Someone gave me a couple cheap chinese 50W LED floodlights, which I managed to open. The drivers were toast, but the LEDs were all good. 96 0.5w 18V 30ma smd leds on each pcb, arranged in 24S x 4P array.Now, ive been searching on google for replacement drivers, but havnt found any drivers with enough output to drive these. I assume they need 432V and 120ma to drive the modules. Please correct me if im wrong.So, Id like to give the LEDs some life again, perhaps on a new project desk lamp, or flashlight, or perhaps build a new driver for them, but I havnt done one before.If you have any good ideas, please share them.Thanks!

author: duak
author_rank: Super Contributor
timestamp: July 08, 2019, 10:27:08 pm
content: Could we have more info on the Floodlight and a picture or two?It might be possible to rewire the LED array to reduce the voltage requirements to something a little more manageable. 432 VDC could lead to some exciting situations if not treated carefully.

author: patrick1
author_rank: Contributor
timestamp: July 09, 2019, 04:44:51 pm
content: just build a capactive dropper circuit. out of good components, - and it is a good idea too cut the string of LED into 4 paralelll strings ;-Dpersonally i like incandescant lights.

author: edavid
author_rank: Super Contributor
timestamp: July 09, 2019, 05:44:26 pm
content: I think it's very unlikely that it has a 432V LED string. Check the wiring again (and I agree, post photos).
Ideas for scope display for an instrumentation product - Page 1
Forum section: electronics / projects

author: JohnnyP
author_rank: Regular Contributor
timestamp: April 09, 2023, 04:35:49 am
content: I incorporated a small Gabotronics scope display on the front panel of a project I designed back in 2015. It works, but I'm looking for other ideas.I googled a bit and found a scope app for Android based on the Raspberry Pi Micro:https://how2electronics.com/diy-smartphone-oscilloscope-using-raspberry-pi-pico/The max sample rate is only 250k, but it might be fast enough, would have to try it.Is there anything for the ipnone, besides Oscium?Ideas and suggestions are welcome.

author: Martinn
author_rank: Frequent Contributor
timestamp: April 09, 2023, 03:44:59 pm
content: What are you looking for?Larger screen, higher sample rate (how much), interactivity, data export, phone connectivity?I am currently working with TouchGFX on an STM32 board. Might also work.

author: JohnnyP
author_rank: Regular Contributor
timestamp: April 10, 2023, 01:54:51 am
content: Watching videos on TouchGFX right now.My user interface is knobs, switches, and LED's. It works but I know users will want more, and it should have a better display. Only the lab techs will want to use a real oscilloscope.

author: Martinn
author_rank: Frequent Contributor
timestamp: April 10, 2023, 02:58:38 pm
content: Well you should really state what you are looking for. You wrote scope, android app, 250ksps too slow (maybe), now knobs, switches, LEDs.I find that too confusing to give a useful recommendation. There are many ways creating a GUI, none of them quick or easy.

author: JohnnyP
author_rank: Regular Contributor
timestamp: April 10, 2023, 09:51:58 pm
content: You are correct. I don't know what I want or actually need, or even if there is a market for it.I've done some vehicle testing and it works, and have been invited to test at a facility used by the magazines.

author: nigelwright7557
author_rank: Frequent Contributor
timestamp: April 10, 2023, 11:01:13 pm
content: I designed a couple of usb scopes with spectrum analyser display too for a pc.One was 3 mega samples the other was 18 mega samples.Both using PIC's.I used external a2d on faster scope.