hybridfree/eevblog-posts huggingface dataset:
Microcontroller soft power button - Page 1
Forum section: electronics / projects

author: Things
author_rank: Regular Contributor
timestamp: November 29, 2014, 11:29:57 am
content: Hi all,I'm working on designing a product that needs to be as physically small as possible. It will incorporate a microcontroller, and have a single button for accessing various modes. It'll have a small inbuilt LiPo battery for power - but the it occurred to me, how do I turn it on and off. Being a LiPo, it'd need to have no draw in the off state, but I also don't really have the room for a separate switch.I've had this idea before, but I couldn't really seem to get it to work. Basically I'd have the switch connected directly to the battery positive, as well as an I/O pin. When pressed, it'd send power into the boost converter, which in turn would power up the microcontroller. I could then use a transistor on another I/O pin to keep it "latched" while the micro is running (or an enable pin on the boost converter, if it has one). This would also make it very easy to incorporate a hard low voltage cutoff to protect the LiPo.However I seem to recall thoughts about this not working for some reason. Said product is just for fun, so things like the microcontroller accidentally rebooting and killing it's own power isn't a big deal.Cheers,Dan

author: 8086
author_rank: Super Contributor
timestamp: November 29, 2014, 11:49:00 am
content: https://www.eevblog.com/forum/projects/an-idea-for-soft-power-with-no-quiescent-loss/

author: Mad ID
author_rank: Regular Contributor
timestamp: November 29, 2014, 11:50:49 am
content: Quote from: Things on November 29, 2014, 11:29:57 amIt will work. You have a PFET on the power signal. The pushbutton pulls the gate of the PFET low and the system start running. The pushbutton has an NFET in parallel which the MCU turns on as soon as it boots. When you want to shut down, just release the NFET. Whola.
Microgripper maximum voltage - Page 1
Forum section: electronics / projects

author: ezalys
author_rank: Frequent Contributor
timestamp: December 25, 2017, 08:36:11 am
content: So I have a collection of 206-0364-01 Tek Microgrippers. They have a maximum voltage of 40 volts written on the side. What exactly sets this? These little clips would be quite useful for looking at the voltage deep inside an older oscilloscope, but I don't want them to arc or melt. Is 40 volts the maximum voltage I should EVER use these to, or is it the maximum voltage it's safe to use while removing and placing the probes with my hands?

author: David Hess
author_rank: Super Contributor
timestamp: December 25, 2017, 02:40:35 pm
content: I suspect that has to do with the insulation rating of the barrel part of the test clip which is only thinly insulated. I would shrink some heat shrink tubing around it if used at a higher voltage.

author: Jeroen3
author_rank: Super Contributor
timestamp: December 25, 2017, 02:50:17 pm
content: 40V is common on test leads not specifically safety isolated. They’ll handle higher voltages fine, but you’re not covered by the manufacturers specification if it fails.

author: Gyro
author_rank: Super Contributor
timestamp: December 25, 2017, 02:55:38 pm
content: The only probes I can remember with specific insulation breakdown issues were the original HP logic analyser ones which used anodized Aluminium barrels.As Jeroen3 says, 40V is a generic rating for non shielded jack plugs etc. A bit of extra sleeving if the barrel is going to be touching other stuff and be mindful of what you're doing.P.S.Quote from: ezalys on December 25, 2017, 08:36:11 amIt's the voltage where you should be seriously considering whether you are wise to be placing probes on the fly.

author: Zero999
author_rank: Super Contributor
timestamp: December 25, 2017, 03:06:40 pm
content: Quote from: ezalys on December 25, 2017, 08:36:11 amRelax, under normal atmospheric pressure, it's actually not possible for an arc to spontaneously form between two points, until the voltage exceeds 327V, which is higher than the peak voltage of 230V mains. An arc can from when the current is interrupted by separating a pair of electrical contacts, or when the mains voltage is higher than it should be.The reason for the 40V rating is purely for insurance purposes. The insulation isn't mechanically strong enough to ensure it won't be damaged by moderate use and cause an electric shock. Don't hold the clips when they're connected to a hazardous voltage, which is typically above 60VDC or 25VAC.

author: alm
author_rank: Super Contributor
timestamp: December 25, 2017, 04:55:12 pm
content: Some uninsulated Pomona clips have a rating of 40V, but up to 250V for hands-off use. So in that case, the rating is purely for human safety. As long as you make sure the circuit is de-energized before handling the clips, you can likely go higher. Just be mindful of shorting to adjacent parts.
Micromanipulator for pushing SMD parts around - Page 1
Forum section: electronics / projects

author: DTJ
author_rank: Super Contributor
timestamp: September 18, 2016, 08:05:58 am
content: I was thinking of putting together a simple panto-graph thingo for pushing SMD parts around when hand assembling. Anyone done this of have any useful gadget ideas?Something to help nudge a fine pitch part sideways a little or press a part down slightly into the solder paste. I thought it might be handy for minimising hand tremble & caffeine shakes.Searching for ideas turned up this little device in the attached picture, it''s got a 4:1 motion reduction. There's a utube video of it in action.I wonder how it would work if a vacuum pickup was fitted to the business end.
Micromint "Bambino 200" - Page 1
Forum section: electronics / projects

author: Hamster
author_rank: Regular Contributor
timestamp: October 06, 2013, 11:31:48 pm
content: Anybody Try out the Micromint Bambino 200 ? I saw this at the Orlando Mini Maker Faire on Saturday, and interested in checking one out, and was wondering if anybody has any experience?product link:http://www.micromint.com/component/content/article/53-products/196-bambino200.html

author: AlfBaz
author_rank: Super Contributor
timestamp: October 07, 2013, 12:33:17 am
content: Quote from: Hamster on October 06, 2013, 11:31:48 pmI might start competing in this market. What the board does will be irrelevant cause it's going to have a cool, catchy name. The "Otra Placa 1000"
Micron MT40A DDR4 data pins swapping - Page 1
Forum section: electronics / projects

author: elektronika
author_rank: Newbie
timestamp: May 24, 2022, 10:37:36 pm
content: I am using in my layout this memory: MT40A256M16GE-075E Bhttps://www.micron.com/products/dram/ddr4-sdram/part-catalog/mt40a256m16ge-075e-autCan I freely swap the data pins within a bytelane to improve my routing, for this memory? I am convinced that the answer is yes, but I really want a second opinion, because I can not afford to make second version to a big 6-layers board (all components are ordered due chip shortage in advance, some of them already obsolete). No place to make mistakes in the schematic.I admit, I am lazy and didn't find with Ctrl+F some hints about pin swapping for this datasheet. Other manufacturers mention these options in their datasheets, but for Micron I didn't find it.Many thanks in advance!

author: Benta
author_rank: Super Contributor
timestamp: May 24, 2022, 10:55:07 pm
content: Within a bytelane, swap whatever you want. This goes for ALL RAMs. They don't even have to match between CPU and RAM.It's only important for ROMs.

author: sd
author_rank: Unknown
timestamp: May 27, 2022, 12:18:29 am
content: If the CPU uses hardware write leveling, you can't swap the lowest bit in the bytelane. Besides that you can swap them as you wish.
Microphone design inquiry - Page 1
Forum section: electronics / projects

author: TheWinterSnow
author_rank: Contributor
timestamp: September 23, 2022, 09:05:45 am
content: Hey all,last year I cam across a design documentation for the THAT 1570. I have spent hours trying to find that documentation again. It is a powerpoint based slides and I have been not able to find it again. The slides go over in detail with equations. The only thing that I have been able t find is this:https://www.thatcorp.com/datashts/AES129_Designing_Mic_Preamps.pdf.That link is a stripped down version of what I used to have on my computer. The powerpoint slides in question had multiple equations for things such as input offset current, input offset voltage, noise and how the relationship between the differential outputs and the feedback were related to gain, noise and THD.If anyone has that presentation that they could share that would be much appreciated. I even tried the wayback machine and still came back empty.Thanks

author: jonpaul
author_rank: Super Contributor
timestamp: September 23, 2022, 09:51:18 am
content: contact THAT directlyVery good support

author: Terry Bites
author_rank: Super Contributor
timestamp: September 23, 2022, 02:45:11 pm
content: THAT, whats not to love?
Microphone LED Driver - Page 1
Forum section: electronics / projects

author: Kishvier
author_rank: Newbie
timestamp: December 16, 2014, 09:29:57 pm
content: Hello all, I've been working on a small project for some friends in which I use a condenser microphone to drive some LED's. I am having one issue though, I get this voltage spike when the circuit turns on at the LEDs (It should just flash them quick?):My circuit knowledge is quite limited as a software guy, but I'm sure there is an easy way to stop the spike from occurring, any ideas? I haven't been able to find a suitable fix through my digging, and figured you folks would probably have some good ideas.Here is the circuit right now, I used a variable voltage source as the mic, as I couldn't find one in the library I was working with and it wasn't my computer. It should work the same?

author: Zero999
author_rank: Super Contributor
timestamp: December 17, 2014, 12:51:35 pm
content: It's to be expected. Then power is applied, it takes time for C2 to charge, causing Q2 to turn on.

author: fcb
author_rank: Super Contributor
timestamp: December 17, 2014, 01:05:46 pm
content: If it really matters that much.Put an NPN transistor (emitter grounded) in the cathode of LED chain - this will act like a switch. Then slug the base with capacitor (10uF+) to ground, and then feed the base with a resistor (perhaps 47K, adjust depending on the transistor gain and response speed) from your switched Vcc rail.I'd probably use a 2N7002 FET and a smaller capacitor and larger resistor instead of a bipolar transistor.
Microprocessor I/O isolation - Page 1
Forum section: electronics / projects

author: iman_os
author_rank: Newbie
timestamp: February 25, 2018, 03:19:29 pm
content: Hi guysI want to isolate my STM 32 Microprocessor I/O pins from digital modules like LCD.LCD digital pins are not using much current but is it necessary to avoid depreciation of Micros I/O which is using for some years or save micro from module fault?any other comments or recommends woud be appreciated .

author: danadak
author_rank: Super Contributor
timestamp: February 26, 2018, 01:23:31 pm
content: Consider quad optocouplers as one method.Regards, Dana.

author: Ian.M
author_rank: Super Contributor
timestamp: February 26, 2018, 04:20:42 pm
content: There is very little point in using optocouplers if both sides share a common ground. Generally, for MCU applications on a single PCB, you don't need I/O isolation unless you need to transfer signals to/from an isolated power domain. However for off-board connections (especially long ribbon cables etc.) you may need bus or line drivers or buffers to improve signal integrity. They are also commonly used for level-shifting.Designing to improve ESD and EMI resistance to reduce the risk of malfunction and even damage is a whole other ball-game, and you have a lot of studying ahead of you to gain even a superficial understanding of the field . . . .
Micropump  - Page 1
Forum section: electronics / projects

author: lilmantis
author_rank: Contributor
timestamp: July 29, 2019, 06:07:09 pm
content: Hello all, I want to build an automatic aquarium fertilizer and I want to use some piezo micro pumps. Can you suggest me some good supplier in Europe? Also some in depth info on how to properly use them, risks, etc. would be much appreciated. Thank you.

author: DaJMasta
author_rank: Super Contributor
timestamp: July 29, 2019, 06:20:46 pm
content: Don't know anything about piezo pumps, but I know something about aquarium dosing, and the standard way is a peristaltic pump. Basically, it's a pump where the mechanics never touch the fluid and that can very finely control dosing, so while they tend to be a bit large, they are very well suited for a wide variety of chemicals in sensitive environments.

author: lilmantis
author_rank: Contributor
timestamp: July 30, 2019, 12:22:40 pm
content: Thank you for the response. Do you have any idea if there are some piezo pumps for medical with long lifetime?

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 30, 2019, 03:50:41 pm
content: Medical mean normally Certified and Certified Stuff mean many €€€.

author: Marco
author_rank: Super Contributor
timestamp: July 30, 2019, 07:28:00 pm
content: Someone is sellingcuriejet liquid pumpson ebay.

author: lilmantis
author_rank: Contributor
timestamp: August 02, 2019, 04:41:26 pm
content: Thank you all for the help and sugestions.
Microstrip-To-Waveguide transition - Page 1
Forum section: electronics / projects

author: lottarn418
author_rank: Newbie
timestamp: March 01, 2022, 07:15:15 am
content: Hello everyone!I'm currently working on a bachelor thesis, where I am going to design Microstrip-To-Waveguide transition. Right now I'm working with a rectangular waveguide - WR12. However, as seen in the pictures that I've posted, the microstrip consists of 2 WR, one on the upper side and downside. My question is that in order to backshort my WR on the upperside, should I assign a perfect E boundary?Also, in order to connect these to WR, I have to implement via holes, but this will for sure increase my simulation time, is there another easy way to connect these to WR?Thanks in advance!

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: March 01, 2022, 10:01:09 am
content: This might be more suited on the RF/Microwave section.When I simulate this kind of structure I would start with a wall instead of vias. I would design this way, and then only towards the end start replacing the wall with more realistic vias.Assigning a perfect conductor could work, or you just cap it with a piece of metal too.

author: lottarn418
author_rank: Newbie
timestamp: March 01, 2022, 10:23:56 am
content: Thank you for the answer! I was also thinking to put walls but since I'm new at HFSS I really don't know where and how I should put the wall, this is the point where I struggle actually. Could you, for instance, sketch an easy picture of what it should look like when it comes to the walls?

author: CaptDon
author_rank: Super Contributor
timestamp: March 01, 2022, 02:10:04 pm
content: Wouldn't your studies and curriculum give you the answers to all of this? MiniCircuits, RHG, Toshiba and many others have been doing this transition for at least 2 decades now being used mostly in mixers and amplifiers for the radar industry. They are typically 'Waveguide in' to an SMA output connector and in the radar business one cadmium coated steel housing contains the waveguide input, the FET preamplifier, the balanced mixer, the tune-able local oscillator and the I.F. amplifier/buffer. Priced around $200.00 USD as a replacement part for RayMarine, Furuno and others. I wish I still had the one I cut open for display so I could send you pictures of the transition part. In most cases it amounted to a probe of about 1/4 wavelength and I forget if the probe was 1/4 or 1/2 wavelength from the rear wall. If you want to play with complex transitions have a look at a 20Db or 30Db waveguide directional coupler with the typical IN/OUT/SAMPLE ports. Some of those are SMA to waveguide to SMA. Cheers Mate!!
Microstrip versus coplanar waveguide - Page 1
Forum section: electronics / projects

author: maticee
author_rank: Newbie
timestamp: July 05, 2023, 04:45:06 am
content: I am currently working on a project that uses a 2.4 / 5 GHz WiFi/BT transceiver that I am trying to route at a target impedance of 50 ohms on the top layer. This trace is routed to a U.FL connector.This is being routed on a 12 layer board with material that has a DK / Er of 3.17.See the following dimensions for the RF trace:Trace width = 4.5 milTrace clearance to adjacent GND pour on same layer = 10 milConductor height (L1 to L2) = 2.5 milI routed this originally as a microstrip design but have since come along many resources talking about CPWG and how it affects impedance. Saturn PCB gives me a microstrip impedance of 50 ohms and a CPWG impedance of 63 ohms. Which would should I design for? I have flexibility on trace thickness and spacing . . .Additionally, at what point does coplanar waveguide become microstrip? Theoretically, CPWG with a very large gap would result in a microstrip trace but the tools do not seem to generate that outcome!

author: jmw
author_rank: Frequent Contributor
timestamp: July 05, 2023, 06:30:46 am
content: 3W or 3*trace width clearance is a one rule to use for when the surrounding ground pour begins the influence the transmission line.The problem with CPWG is there are no great approximate or quasi-analytic solutions. I would only trust a field solver for impedance characterization, not Saturn PCB.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 05, 2023, 11:03:38 am
content: The non-answer: place the connector within say 10mm and the trace impedance is basically irrelevant.(Maybe this isn't applicable for various reasons, maybe it leads to insight that was otherwise missing, who knows.)Tim

author: VEGETA
author_rank: Super Contributor
timestamp: July 05, 2023, 11:25:49 am
content: does waveguide with vias method also benefit switching PSU designs?and at which frequencies will such solutions starts being necessary?

author: maticee
author_rank: Newbie
timestamp: July 05, 2023, 08:18:50 pm
content: Any free solvers that you would recommend?

author: ejeffrey
author_rank: Super Contributor
timestamp: July 05, 2023, 09:15:34 pm
content: Quote from: maticee on July 05, 2023, 08:18:50 pmI've had good results with wcalc for standard geometry impedance calculation and atlc2 for arbitrary waveguide calculation.Keep in mind that CPW can be with or without a back side ground plane. CPWG converges to microstrip when the gap is large compared to the substrate thickness, but plane CPW does not. This is not usually used on PCBs, its more of a chip scale thing where the geometries are small and the back side of the substrate is far enough away to ignore.The main advantage of CPW for PCBs is that you can avoid sending your return current through ground vias. You can also adjust your center trace width independent of the substrate to more easily match connector / packages. This is especially helpful if you want to use a 2 layer PCB since microstrip will be huge.Honestly for a short antenna connection for 2.4/5 GHz it's probably not that critical.
Microwave AutoCook (temperature?) Sensor - What is it  exactly? - Page 1
Forum section: electronics / projects

author: ornea
author_rank: Unknown
timestamp: August 01, 2017, 04:23:06 am
content: Removed what appears to be the AutoCook sensor from a low price microwave oven that died. See images attached.Trying to work out how it ticks.I have tried various DHT protocols with no response.Also Hooked up as follows:-Red-5VBlack-GndWhite to scope.Trace sits at approx 1.8V with no deviation when pointing at a hot cup of water.Tried pull-ups, pull-downs.Various googles of images with no hits.Anyone have any idea how these work or how to wire them up.Cheers

author: Someone
author_rank: Super Contributor
timestamp: August 01, 2017, 04:40:57 am
content: First guess confirmed with a simple google:http://products.geappliances.com/appliance/gea-support-search-content?contentId=18845

author: ornea
author_rank: Unknown
timestamp: August 01, 2017, 04:49:55 am
content: Hi Someone,Google searches I did hinted at humidity but I have yet to find any info on how they work or how to hook them up.I also failed to get any hits on image match.

author: ornea
author_rank: Unknown
timestamp: August 01, 2017, 04:57:25 am
content: Update ... Searching Microwave humidity sensor has provided some hits.
Microwave Doppler Modules - Page 1
Forum section: electronics / projects

author: mark5009
author_rank: Contributor
timestamp: November 27, 2012, 11:02:55 pm
content: Hi, all.Has anyone had any experience with X-band Doppler modules, such as Microwave Solutions' MDU2000  or New Japan Radio's NJR4176 series ? The datasheets on these guys all seem a little sparse...My application is low-end speed measurement (measuring the velocity of an approaching object <10m prior to impact) and I figure a small Doppler unit is just the trick. I guess that these units will require some DSP handling (freq domain to time domain shift) as one of sheets, in a side note, mentions that the unit produces a shift 70Hz per m/s target velocity in the 10GHz range.Any thoughts on how to approach such a problem?Thanks .. mark.http://www.microwave-solutions.com/contents/en-uk/d12.htmlhttp://mc.njr.co.jp/eng/products/sensor/x-doppler.html

author: RCMR
author_rank: Frequent Contributor
timestamp: November 28, 2012, 04:28:37 am
content: You can use DPS processing if you want but you don't have to get that complex to get good results.Just take the output from the mixer, amplify it, square it off (use a schmidt trigger if you want) then measure the frequency (or the interval between pulses) -- do a little (very simple) math on that number and there's your velocity.DSP will be necessary if you want to be able to detect multiple reflections of similar magnitude) but if you can be sure that there's only going to be one major reflector in the path then it's *very* simple stuff.
Microwave layout question - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 18, 2015, 10:20:23 am
content: I've been trying to find out what these are called. Sheer curiosity. Easy to describe them, but are they actually named or anything???Typical example: a 2.45GHz RF power amplifier, with big fat pads/microstrip connecting to the transistor. Around the edges and corners of these pads... small pads, chits of copper. Isolated, just sitting there, dotted around the edge. Sometimes a shorting strip is soldered over from the main pad to one or more of them, presumably to reduce impedance slightly.It seems strange to me, because they aren't large enough to be useful at the fundamental frequency. Maybe to filter (trap or reflect?) harmonics around the periphery of said traces, but... no idea.Here's a pretty strong example:http://www.nxp.com/documents/data_sheet/BLL8H1214L-500_1214LS-500.pdfthe blocks along the transmission lines appear to be bandpass filtering / matching, of course.If it's just for tuning, then it would make sense for test boards, like this... but I believe I've seen those stray pads in production stuff too. So I suspect there is some other purpose. But I can't intuitively see how their electrical length, impedance or coupling would be valuable in practice.Tim

author: KJDS
author_rank: Super Contributor
timestamp: March 18, 2015, 10:31:48 am
content: It's just for tuning.Matching high power transistors is about as difficult as RF gets, not because it's very difficult, more because each time you get it a bit wrong and the £200 transistor dies your bosses hits you on the head.

author: SeanB
author_rank: Super Contributor
timestamp: March 18, 2015, 06:25:30 pm
content: They perform the equivalent of inductors and capacitors in lower frequency circuits, matching the transmitter output impedance to the typical 50R transmission line or following stage. They are adjustable with a strap or a grinder because the manufacturing is going to have variation, with solder and such on the pads having an effect on the impedances, so these are used as LC matching elements, and some perform the job of being harmonic filters to reduce spurious responses. The positioning and the spacing changes the capacitance ( roughly) and the size roughly the inductance. the shorting bar you describe will be to increase inductance slightly ( if the shorting strip is long) or reduce the inductance of the block.In older waveguides you could often do a tuning change simply by taking the copper waveguide section and pressing in on the long faces, decreasing the spacing inside would change the attenuation and response of the waveguide. To tune further you simply used brass screws or ferrite discs epoxied to the screws to change the characteristic inductance at that spot.
microwave oven transformer as autotransformer - Page 1
Forum section: electronics / projects

author: jonovid
author_rank: Super Contributor
timestamp: November 26, 2016, 02:11:54 pm
content: 1000w microwave oven transformer as a autotransformer projecthere is a 1000w microwave oven transformer taps at 120v 220v 240v LT 18v the deadly 1kV HT I cut this off.3 hrs of grinding & cutting. this is posted as a demonstration of how removing transformer windings can be accomplished without cutting the Core. shell or damaging other wingdings on the transformer.at first I cut a gap in the winding so it can be moved back 5mm with a wedge and a hammer. then I use a hack saw to cut off the end now that its 5mm out from the core with less of a cross section for cutting. then i hit it with a power drill to take out some of the winding inside the core, before using a hammer and screwdriver to punch the remaining bits of winding out of the core. I will post more on this. do not know if anyone goes to this much work. just to re-purpose a used microwave oven transformer?have not run it as the 1kv winding was too dangerous. not yet tested it like this. as I need to wire it up in a safe place .updatedid not have a insulation resistance megger test.AC test no load at the wall is 250v. - 110 tap is 121v, and 220 tap is 226v, 19v is the two little lift tabs, and the red LT is 3.5v .little humming sound.next is to gut an old PC ups power supply for its caseupdatethe transformer is now mounted on a base plate from a steel case before wiring it up . shown with a 5Amp circuit breaker, but still has some missing parts.the used ups power supply base plate has its own plastic feet.updateProject completed successfullyits up and running, now looking for more space on the bench.

author: jonovid
author_rank: Super Contributor
timestamp: December 03, 2016, 05:56:24 am
content: project completed

author: edpalmer42
author_rank: Super Contributor
timestamp: December 03, 2016, 07:24:36 am
content: Nicely done!I've seen some videos on Youtube that used a microwave transformer as a spot welder. All you'd need to do is wind the new secondary through the holes in the core. It only takes two or three turns of welding cable. You could get even more value out of your unit.

author: jonovid
author_rank: Super Contributor
timestamp: December 03, 2016, 10:40:31 am
content: totally unaware of just how many others on YouTube, have re-used microwave oven transformers the same way as I did.lack of forum interest is now understandable.Your right,Yes this project has more as a spot welder. .....or maybe high current DC power supply with car alternator diodes.as the front panel is un-used
Microwave oven transformer laminations - Page 1
Forum section: electronics / projects

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: May 03, 2020, 11:44:24 am
content: I am constructing a spot welder for Li-ion cells so removed the secondary winding from a couple of microwave transformers. One transformer was wound with aluminium wire and was from a 'no brand' cheapo oven. The other had copper wire and was from a Panasonic oven. I decided to use the copper wire unit, but noticed that it had extra laminations in the slot between the primary and secondary windings. The aluminium transformer did not. I may have to remove these laminations to get another turn of the heavy gauge secondary wire and wondered what their function was before I do so. Any theories?BT

author: Prehistoricman
author_rank: Regular Contributor
timestamp: May 03, 2020, 11:57:06 am
content: It's called a magnetic shunt. There is a good answer on Quora (as much as I dislike that website):https://www.quora.com/What-is-the-purpose-of-the-magnetic-shunt-that-is-in-most-microwave-power-transformers-Can-the-shunt-be-safely-removed-when-winding-a-single-replacement-secondary

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: May 04, 2020, 02:30:38 am
content: Thanks for that info.Fascinating, and something that I was unaware of. I did lash up the welder on the bench and it worked well so I have tidied it into a case, but I will experiment with the transformer in the light of this new info before I go any further.BT
Microwave talks - Page 1
Forum section: electronics / projects

author: dsierra
author_rank: Newbie
timestamp: September 20, 2015, 07:22:38 pm
content: Hi all,I saw some teardowns of microwave devices that seems that there are magic inside. A work mate, Roger Hoyland, which has a big knowledge about microwaves and an international patent of a microwave phase switcher, is going to held some talks about them:- So you think you know about microwaves…?Thursday September 24, 10:30 GMT (GMT+1 Summer time)Live streaminghttp://iactalks.iac.es/talks/view/809- Are Mobile phones a Danger to Your Health?Tuesday September 29, 10:30 GMT (GMT+1 Summer time)Live streaminghttp://iactalks.iac.es/talks/view/810http://iactalks.iac.esBest regards,Diego.

author: sarepairman2
author_rank: Frequent Contributor
timestamp: September 20, 2015, 07:54:22 pm
content: i just got a microwave sweep generator
Microwave/RF through a via - Page 1
Forum section: electronics / projects

author: itdontgo
author_rank: Regular Contributor
timestamp: August 29, 2012, 11:02:52 am
content: Hi,It would have been convenient on occasion to use a via to connect very sensitive RF parts of a circuit but I have always designed around it. For example it would be beneficial in one project I worked on to have a surface mount GPS antenna feed in to a module which was mounted on the other side of the board but instead I designed everything on the one side.Presumably a via would act like an inductor (and capacitor where the boards overlap) and you would therefore require different matching components (in this case) from the aerial to the module to compensate for the inductance. Beyond that though I would expect the return loss to show a significant decrease but I cannot quantify it. Would anyone like to hazard a guess in the GPS/GSM 1500MHz+ range?I never designed a board to test the real world effect as I always assumed it would be a poor solution. I also dont have easy access to Agilent ADS/Gensys or similar so have never 'wasted' any time on it.

author: nctnico
author_rank: Super Contributor
timestamp: August 29, 2012, 01:17:26 pm
content: You could download a free limited functionality copy of Sonnet in order to simulate the effect. IMHO what you basically want is that the via has the same impedance as your trace to minimize the mismatch and reflections. I found the following article (use the 'pdf version' button to get the PDF version with pictures):http://www.edn.com/design/components-and-packaging/4330788/Designing-controlled-impedance-vias

author: itdontgo
author_rank: Regular Contributor
timestamp: August 30, 2012, 05:49:15 am
content: Thanks for that very interesting. I didn't think of doing that!
Micsig DP700 CMRR measurement using the Bode 100 and the B-AMP12 amplifier. - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: November 30, 2024, 12:52:47 am
content: I recently purchased the Micsig high-voltage differential probe and wanted to measure its Common Mode Rejection Ratio (CMRR) to evaluate its performance. Dave Jones made similar CMRR measurent but did not have the B-AMP12 amplifier which outputs a large signal. The measurement is more accuate than what Dave Jones made.CMRR is an important specification for differential probes, as it indicates how well the probe rejects common-mode signals while measuring differential signals. To perform this measurement, I used the Bode 100 network analyzer, which is ideal for assessing the frequency response of devices like differential probes.In this guide, I’ll walk you through the steps of setting up the Bode 100 to measure the CMRR of the Micsig probe. I’ll also show how to measure the CMRR of a Pico Technology probe under similar conditions, allowing for a direct comparison between the two probes.
Mid-End Voltage Regulators are Better than Low-End Bandgap Voltage References? - Page 1
Forum section: electronics / projects

author: niconiconi
author_rank: Frequent Contributor
timestamp: October 13, 2022, 06:15:35 pm
content: It's my observation that low-end bandgap voltage references can perform even worse than a mid-end voltage regulator (which, of course, is also based on a bandgap reference). In particular, the "free" references embedded in the ADC/DAC of microcontrollers are the worst.For example:TL431, standard grade:Initial accuracy: ~2%Full temperate range: ~3%long-term drift: no data, but TI said "a typical acceleration test of 500 hours at 150C, the device still meets specifications."ATmega328P:Accuracy: 10%Temperate drift: no dataLong-term drift: no dataPIC16F1574:Accuracy: 5%Temperate drift: no dataLong-term drift: no dataNow let's consider some specifications for mid-end voltage regulators.LM317 (not really mid-end, more like low-end):Accuracy (full temperate range): ~4%Temperature drift (0°C to 125°C): 0.7%Long-term stability (25 °C): 0.3%/1k hr typical, 1%/1k hr max.LM1117:Initial accuracy: 1%Full temperate range: ~2%Temperature stability: 0.5% typicalLong term stability (125°C): 0.3%/1k hr typicalMCP1700:Initial accuracy: 2%Full temperate range: ~3%Long-term drift: no dataTLV733:Initial accuracy: 1%Full temperate range: ~1.4%Temperature stability: 0.5% typicalLong-term drift: no dataTherefore, my conclusion seems to be that if you need a slightly more accurate reference and you're already using LDO on the circuit board, it's a great choice to use the same power LDO as the reference. It's inexpensive, readily available, and already in the BOM anyway. Either a separate one, or even the same one from the power rail if the load is a micropower load like a single microcontroller. The LM1117 and TVL733 look even better than a low-grade TL431! The resistor divider will introduce more error and drift, but it's still a small error than the built-in MCU references.Comments? Any trap for young players?

author: Someone
author_rank: Super Contributor
timestamp: October 13, 2022, 09:41:19 pm
content: Quote from: niconiconi on October 13, 2022, 06:15:35 pmThere is your trap, regulators are typically specified across some "typical" operating range and often have poor regulation as the output approaches zero current.
Midi instrument with velocity - beginner looking for advices - Page 1
Forum section: electronics / projects

author: piwicode
author_rank: Newbie
timestamp: March 19, 2024, 08:39:11 pm
content: Hi there,I’m working on midi keyboard wit the shape of a bandoneon 4.All the design are free to use herehttps://github.com/piwicode/bandoneonIt works well on a breadboard, and I would like to share with you the current state of the design. This is my first PCB board, and I’m looking for feedback on schematics and mostly on the PCB. More eyes see more. If you want to share something, try to provide explanation, a link some documentation or calculation so that I can ramp up.Here is a viewer for the PCB:https://kicanvas.org/?github=https%3A%2F%2Fgithub.com%2Fpiwicode%2Fbandoneon%2Ftree%2Fmain%2Fboards%2FbandoneonHere we go:The instrument has 71 keysI want to measure velocity and avoid manufacturing pushbuttons, hence I use magnetic keyboard push buttons 2- The position is measured by 71 hall effect sensor SS39ET- The analog signal is converted by 9 MCP 3008- I use an Adafruit Feather M4 to bitbang 9 SPI buses in parallel- The bus frequency is 2 Mhz the voltage is 3.3V.- The PCB uses 2 layers. Maybe that is a mistake, but I would like to use 2 layers if this can worksI put ground fill on two faces: the one on the back is for return current, the one on the front is to avoid wrapping.I have no idea of what I’m doing with regard to return current, crosstalk and track size. Please let me know if you know more.Thank you to everyone who take a look.
Midland Alan 48 Plus radio help wanted - Page 1
Forum section: electronics / projects

author: christopher iles
author_rank: Regular Contributor
timestamp: June 13, 2015, 09:58:15 am
content: Hello AllDoes anyone know how to put this radio onto 10m please?All help appreciated.Chris. G0VOE.

author: Deathwish
author_rank: Unknown
timestamp: June 13, 2015, 10:17:05 am
content: http://www.mods.dk/view.php?ArticleKey=c9bc734c0663a142b7bec265098f8dbf&i=Midland-Alan-48-PLUS-Modification-40-ch-to-400-am-fm-for-Midland-Alan-48-Plus

author: christopher iles
author_rank: Regular Contributor
timestamp: June 14, 2015, 05:47:48 am
content: Thank you for the link. Seems very easy to do!
Mifare classic 1k dump and edit - Page 1
Forum section: electronics / projects

author: chrisenglish5690
author_rank: Newbie
timestamp: July 19, 2019, 11:12:22 am
content: I’m looking for information on reading these cards? I have a reader and I’ve managed to get the key for sectors 3-6 but I try to read the dump in hex editor and it doesn’t really show anything?Can someone direct me?Many thanksChrisSent from my iPhone using Tapatalk

author: Chriss
author_rank: Frequent Contributor
timestamp: July 19, 2019, 11:55:22 am
content: Hi!I'm not sure does my writing will help you, but think about it.Maybe the dump is crypted in some way and have to be decrypted to get some reasonable infos in hex editor.I saw that kind of dumps many times before...My best regards.Sent from my SM-J500F using Tapatalk

author: chrisenglish5690
author_rank: Newbie
timestamp: July 20, 2019, 08:32:53 am
content: Quote from: Chriss on July 19, 2019, 11:55:22 amAny further info? I can’t really find much online about it! I’ve used a python reader and it pretty much comes back with the same thing?Any help would be appreciated. I am going to use the card and take another dump and diff the dumpsSent from my iPhone using Tapatalk
Mike's Electric Stuff Flyback Driver Circuit - regarding role of a capacitor - Page 1
Forum section: electronics / projects

author: KJ-90
author_rank: Contributor
timestamp: June 10, 2017, 04:25:25 pm
content: On the well-known Mike's Electric Stuff website, he has developed a driver circuit which works quite well with modern fly back transformers used in CRT television sets. The circuit is available herehttp://www.electricstuff.co.uk/marxgen.htmBeside the IRF830 MOSFET is 12nF 400V capacitor, paralleled by a 150V Zener diode. I was wondering what the 12nF 400V capacitor does. I believe the 150V Zener diode is to protect the circuit from a strong back EMF effect. What would happen if a larger or smaller capacitor was used in place of the 12nF unit?

author: bktemp
author_rank: Super Contributor
timestamp: June 10, 2017, 04:44:02 pm
content: The capacitor forms a resonant circuit, recycling the unused energy otherwise wasted in the snubber of a conventional flyback circuit.The operation is described here:https://www.repairfaq.org/sam/deflfaq.htm#dshdf

author: calexanian
author_rank: Super Contributor
timestamp: June 11, 2017, 02:51:14 am
content: +1 for resonant circuit. Perhaps its time for Dave to do a fundamentals video on the basic tuned oscillator/amplifier circuit.
MikroC PIC ADC? - Page 1
Forum section: electronics / projects

author: AcHmed99
author_rank: Contributor
timestamp: January 08, 2011, 02:30:16 pm
content: Any

author: djsb
author_rank: Super Contributor
timestamp: January 08, 2011, 03:07:04 pm
content: Unfortunately this compiler hides a lot of the setup code in the inbuilt functions or header files that are included at compilation. I have recently bought the EasyPIC6 board myself but I will not be using the bundled compiler. I much prefer CCS PCM or Hi-Tech Lite (included with Mplab) as they are more flexible.Have a look through the assembly listing (file extension .lst or .asm) and check if there are any assembly instruction sequences similar to code snippets in the Microchip datasheet. The microchip forum is another source of help.David.

author: Simon
author_rank: Unknown
timestamp: January 08, 2011, 05:25:21 pm
content: well i use mikroeBasic so can't answer for C but in basic I still have to write to the ADC registers to set them up much like i would in assembly

author: arcom
author_rank: Contributor
timestamp: January 09, 2011, 12:42:35 am
content: A/D initialization and acquisition is done inside the "ADC_Read" routine. Clock is set to RC and delay depends on selected oscillator speed. You can see this if you look at the ASM file (View -> Assembly; or just open the file from the project folder).
MIL-217 Weakest link philosophy for SMD - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: June 06, 2023, 08:16:34 pm
content: I don't understand the MIL justification for using 'weakest link'. (MIL-HDBK-217F, NOTICE 2, Section 16.2).Why is it that once package thermal expansion is factored in, only the 'weakest link' is considered - surely we still have a simple MTBF figure, all we have done is make it more accurate?For instance if there are 2 SMT devices with the same package, and they (both) share the "weakest link" attribute, then how can the existence of the 2nd device be ignored?As I see it, after accounting for thermal cycling, the MTBF of both devices would then add in the usual way, giving a new MTBF that is half that for one device.Further, I also wonder how we can ignore other SMT devices, even those with somewhat lower 'failure rate'.(Note: I'm new to the whole MIL-217 thing, and apologies if this post is not sensible.)

author: Mario Blunk
author_rank: Newbie
timestamp: August 06, 2025, 02:15:12 pm
content: Hello,your question has caught my attention. Even if I don't have an answer to your question. So many times I have studied MIL-HDBK-217F but never stumbled over section 16.2. So here is my assumption of what is meant:1. It is indeed strange to assume that only one SMT device should be of interest while all the others are to be ignored (as described in the begin of the section). 2. The example given in that section has a resulting failure rate of 0.4/10^6h. From the introduction text of the example I follow that this figure must be added to those of all other components. Cite: "his failure rate is added to the sum of all of the component failure rates on the circuit board." So other components do matter and should not be ignored.3. The calculation must be performed for each SMT device and the outcome added as if it where a device.Does that make sense ?

author: 741
author_rank: Frequent Contributor
timestamp: August 06, 2025, 07:54:40 pm
content: HiMany thanks for taking the time to respond.I will have to look again - because it seems I have 'missed' an important detail.RegardsStephen
MIL-DTL-5015 Connector with 230V AV Voltage - Page 1
Forum section: electronics / projects

author: batteksystem
author_rank: Regular Contributor
timestamp: August 16, 2018, 02:19:29 am
content: Anyone has tried using these old military spec connector with AC voltage 230V before? I don't think they have issue with American 110V. However, I am not sure if we can use 230V on them as they are probably not designed for such voltage for their purpose.We actually want to use them to delivery AC 230V power to a air-sealed enclosure. We planned to use the exact one at the bottom, but of course not china made. Thanks.

author: rstofer
author_rank: Super Contributor
timestamp: August 16, 2018, 02:11:50 pm
content: It can handle 3000V RMS if is has an MS Service Rating of 'I' - pins spaced 5/16" apartIt can handle 500V RMS if it has an MS Service Rating of 'A' - pins spaced 1/16" apartPage 26 here:https://www.peigenesis.com/images/content/pei_tabs/amphenol/ait-ms-series/new-thumbs/tech-specs1.pdfYou need to find the contact arrangement where the pins have at least 1/16" spacing:http://www.amphenol-aerospace.com/pdf/catalogs/5015_Catalog.pdfSomewhere in that catalog there will be a way to configure the connector. If not, give them a call.

author: SeanB
author_rank: Super Contributor
timestamp: August 16, 2018, 07:29:37 pm
content: 29/17 is not recommended for use above 200VDC peak, because of creepage in the connector backshell. If you can use a version with a lot fewer pins, and preferably use a separate 3 pin version in a 14 backshell, which has larger pins and bigger separation. Yes you can have 400VDC ( or 250VAC) between pins at STP, but not over the full environmental range of the connector. In high altitude, high humidity or high vibration you can get flashover or leakage between the pins or the shell.You will also want to have the plug side ( or whatever is going to be exposed to the elements) be potted, which does make the cable rather non repairable, as you will have to fill the rear with a flexible potting compound, after crimping the socket pins and mounting them, and the same for the backshell inside the enclosure.

author: batteksystem
author_rank: Regular Contributor
timestamp: August 17, 2018, 04:58:00 am
content: We actually used the 20-29 17-pin version from hirose. It is a solder only version, so we solder and pot them for both plug and socket. I think as long as there is no air gap in the connector backshell (potted with epoxy), then at least theoretically it fulfill the creepage requirement?

author: helius
author_rank: Super Contributor
timestamp: August 17, 2018, 05:52:04 am
content: It is outside my direct experience, but I think epoxy potting does not qualify as flexible*. You would be looking at acrylic, silicone, or urethane resin for that.* and also is not the best for dielectric isolationSeehttps://www.lightingglobal.org/wp-content/uploads/2013/09/63_issue14_part-iii_corrosion_technote_final.pdfhttps://blog.paryleneconformalcoating.com/best-conformal-coating-for-moisture-and-chemical-protection