hybridfree/eevblog-posts huggingface dataset:
estimating gate driver supply requirements? (double check my calc igbt) - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: October 03, 2014, 06:37:04 pm
content: So I need a isolated supply for my gate driver and I am wondering how to guestimate the supply current requirement knowing Ipeak.I know that Ipeak will be 30A, 2uC from -15->15V, the switching frequency is 30KHz. How do I go about getting a number?''I put 2x the charge into the gate per cycle, meaning 4uC/0.00003 seconds. 30KHz.a coulumb is 1A/S, so I have a proportion of 0.000004=0.00003, x = 1, meaning 1*0.000004=x*0.00003, 0.000004/0.00003 =0.13333 coulumb of charge needed per second, meaning that theoretically a 150mA supply with a smoothing capacitor should be able to handle the draw, @30KHz.but, that is over +- span, so that means, that that positive and negative supply must each be able to handle 75mA right?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 04, 2014, 12:25:15 am
content: You can think of it in a few ways, all equivalent:- Delivering charge twice a cycle, but it divides between supplies (as above)- Suppose -15V were ground instead: now you're dumping 2uC from +30V into the gate, and discharging it (no supply draw during the event, though energy is dissipated in the driver and resistances). Average is 2uC * 0.03MHz = 0.06A, through one supply ('top' to 'bottom'). As long as GND, +V and -V are thoroughly bypassed, the supply currents will average out, and you don't have to worry about GND current, the +V/-V draw will remain equal.- Or, consider that the driver alternates between +V switch to G, and -V switch to G. +V switch dumps 2uC every 30kHz ==> 60mA. -V switch dumps the other half of the time, 2uC every 30kHz. Same thing.So, total power is around 30V * 0.06A = 1.8W, a 3W converter would be reasonable.BTW, be weary of charge ratings on power IGBTs. They like to shuffle around the gate voltages they test at. Sometimes +10, sometimes +15 positive peak; sometimes 0, -5, -10 or -15 negative peak. If it doesn't say what they did... don't buy it, look somewhere else. Also, *nobody* makes SPICE models for them.FWIW, gate capacitance is quite substantial at negative voltages. Something about MOS capacitors and charge distribution and spooky stuff like that. It's not like the positive slope where the  capacitance is actually quite low (not counting the Miller step). So the Q_G for +/-15V is somewhere neardoublethat of 0-15V.Tim
Estimating inductance of a coil (lack of measuring equipment) - Page 1
Forum section: electronics / projects

author: rbm
author_rank: Regular Contributor
timestamp: March 12, 2017, 03:49:12 pm
content: Is there any method to estimate the inductance of a transformer primary for those, like myself, without the means to measure it? I've read the technique to use a frequency generator to determine the frequency where the amplitude of the injected signal is half and then calculate. But I don't have access to a frequency generator so can't empirically determine the inductance of the transformer primary.It's a microwave oven transformer primary so the wire gauge is large and number of windings low. I'm guessing its inductance is also low. I'm using this as part of an underdamped LRC tank circuit and am trying to estimate the peak current that would be drawn.

author: JimRemington
author_rank: Regular Contributor
timestamp: March 12, 2017, 04:28:01 pm
content: The transformer is designed to work at 50 or 60 Hz, so you should be able measure the impedance using a line AC source, a multimeter and a series resistor.

author: Benta
author_rank: Super Contributor
timestamp: March 12, 2017, 05:30:41 pm
content: Do you have a 'scope? Then it's quite easy.

author: rbm
author_rank: Regular Contributor
timestamp: March 12, 2017, 11:40:33 pm
content: I have a 60MHz scope. What is the process using the scope? Is it using the 1kHz 1Vp-p reference from the scope?

author: Benta
author_rank: Super Contributor
timestamp: March 12, 2017, 11:55:51 pm
content: Quote from: rbm on March 12, 2017, 11:40:33 pmYep. Let the 1 kHz output drive the coil. insert a series resistor in the circuit and measure the voltage over the resistor with the scope.You should get a nice triangle waveform, and from this you can compute the current through the coil, and from this the inductance.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 13, 2017, 12:56:43 am
content: Hi,I can do a quick estimate without doing any measurements.The magnetizing inductance of a line frequency transformer so that the magnetizing current is small. Assume that the microwave is 700WSo the load current will be 700W/120V = 5.8ALet us estimate the magnetizing current is 1/10 of the load current so 0.6A(If you connect an Amp meter in series with the primary and measure the primary current with no load and the transformer powered from a wall outlet. If you have a measured value, you can use the measured value instead of 0.6A estimated)Impedance = 120V / 0.6A = 200Impedance = 2 x pi x F x L = 200L = 200 / (60Hz x 2 x pi) = 0.53 HenriesThe inductance will be quite high.Regards,Jay_Diddy_B
Estimating tiny Li-Ion battery lifespan (56mAh with 2 days per cycle) - Page 1
Forum section: electronics / projects

author: ivan747
author_rank: Super Contributor
timestamp: December 16, 2015, 07:50:35 pm
content: I was thinking the other day about smartwatches. As you might know, these aren't the most easy to repair gadgets out there.Watching a video about the Pebble Time Round. It is very small and very thin, thus it uses a very small 56mAh battery. They get 2 days of battery life out of that mostly thanks to an e-paper display and using a small ARM Cortex MCU rather than a huge smartphone SOC.I tried to estimate the battery lifespan of this thing assuming the following:*The battery will last 500 cycles*It runs for 48 hours*There is no capacity loss over time*It charges slowly enough so that heat isn't a concern..With these calculations I got a 2.75 year lifespan out of the watch, which is rather low. I'm worried I am not taking into account factors like:*Charging speed (the manufacturer claims the device can get 1 day of charge for 15 minutes on the charger. I am not sure how hot it could get under those conditions. I can estimate the amount of power that goes into the battery at a given time, but heat depends upon internal resistance of the battery.*Battery cycle count could be wrong for this very small battery size.*I didn't take into account capacity loss over time (I know it's going to be a curve, how do I compensate for this?)What are the effects of the points I have mentioned?

author: stmdude
author_rank: Frequent Contributor
timestamp: December 16, 2015, 08:50:23 pm
content: Your estimates are a bit on the low side.When I speced batteries for one of the biggest consumer-electronics manufacturers out there, our rule of thumb was that after 1000 cycles, the battery should still have 80% of its original capacity.I.e, it's nowhere near unusable even after 1000 cycles.I'm sure you could get worse batteries, but we weren't really paying top dollars for the cells, so I think it's a pretty common spec.This is of course assuming that the battery isn't mistreated somehow (not perfectly tuned charging parameters, discharging it too low, etc).

author: ivan747
author_rank: Super Contributor
timestamp: December 16, 2015, 11:24:46 pm
content: Quote from: stmdude on December 16, 2015, 08:50:23 pmSo the lifespan is closer to 5 years. I think it's going to be on it's way to obsolescence by then (maybe not planned obsolescense. The original 3 year old design is still being produced and sold).
Estimating trace inductance for capacitor placement - Page 1
Forum section: electronics / projects

author: sheitbrink
author_rank: Newbie
timestamp: June 27, 2018, 06:56:29 pm
content: I was wondering if anyone had any ideas on the best way to estimate trace inductance on a PCB when it relates to the placement of +10uF bulk caps.I'm using a ground plane with 13mil spacing up to the top signal layer. I was wondering if I could use the per unit length inductance off of a microstrip impedance calculator to estimate the inductance of the trace. So I would just take this:L = (nH/in)*(trace len)This would be used to estimate the impedance ip to 10's of Mhz.The reason I ask is because experts in the field claim that inductance is a really misunderstood concept. They also throw around words like self, partial, & mutual inductance, and I don't know which one this nH/in one is.

author: iMo
author_rank: Super Contributor
timestamp: June 27, 2018, 08:36:21 pm
content: IMHO it has a little sense to mess with a track inductance(s) when talking +10uF bulk capacitor(s) placement.. What is the impedance of a 10uF bulk capacitor at 10MHz??

author: sheitbrink
author_rank: Newbie
timestamp: June 28, 2018, 03:00:12 pm
content: If you look at the following impedance plot:https://drive.google.com/open?id=1kYZlxtzwTjZC-T8o9qigUJEdqroSlb_Lyou can see what the impedance is for a 10uF ceramic capacitor. the reason the plot is V shaped is because of the ESL of the cap. If you crunch some numbers you get about 0.63nF. But, if you had to put a few cm of trace between your load and the cap, the trace inductance would be higher.Here is a plot with the orginal plot, and 2,4 and 8nH of inductance added:https://drive.google.com/open?id=1j_3GMYVun_jgU2s5ZuUIKg_KdPUq7crGyou can see you start to get an effect with in a decade of the capacitors new resonance and really takes over after that.I suppose what was asking was if anyone knew how to estimate this esl on a trace using cheap microstrip calculator, and not spend $$$ to do some sort of EM simulation.
ET2764Q eprom - Page 1
Forum section: electronics / projects

author: Wawavoun
author_rank: Regular Contributor
timestamp: April 12, 2021, 10:07:02 am
content: Hello there,I own one of these eprom.I am looking for the datasheet, no way to find it on the internet !Or at least I will be happy with programming voltage VPP value...Thank you, regards.Philippe

author: retiredfeline
author_rank: Frequent Contributor
timestamp: April 12, 2021, 10:33:26 am
content: This page suggests that it's 21V.http://www.ezoflash.com/adapters/dip28c1/settings.htm

author: coromonadalix
author_rank: Super Contributor
timestamp: April 12, 2021, 11:05:04 am
content: yep they gives th2764 as an equivalent for the same specs ...

author: Wawavoun
author_rank: Regular Contributor
timestamp: April 12, 2021, 04:40:32 pm
content: Thank you !
Etch it yourself SMD to DIP adapters Eagle artwork? - Page 1
Forum section: electronics / projects

author: Winston
author_rank: Regular Contributor
timestamp: June 26, 2013, 04:58:42 pm
content: This one is extremely handy and I'd like to find similar examples for other SMD package types if their Eagle .sch and .brd files are available on-line somewhere:http://my.opera.com/raphman/blog/2007/10/24/smd-to-dip-adapter-board-layouts
Etched inductor arrays - Page 1
Forum section: electronics / projects

author: 4to20Milliamps
author_rank: Regular Contributor
timestamp: March 20, 2013, 12:31:27 am
content: This kind of a fringe subject, but after I was successful at etching a fractal antenna for my t.v. I became interested in etching inductors in fractal patterns and connecting them in series and parallel arrays just to see what kind of inductance I could get.I was just wondering if anyone else had tried this and the results they got.Don't laugh at my duct tape it is temporary just to prove the concept. (actually it's probably permanent)

author: ftransform
author_rank: Frequent Contributor
timestamp: March 20, 2013, 12:35:18 am
content: can you provide more information about your TV antenna I am interested. Do you have a design program for this?

author: 4to20Milliamps
author_rank: Regular Contributor
timestamp: March 20, 2013, 12:43:50 am
content: Store bought RCA antenna> zero channelsEtched fractal antenna> 8 channelsI used the template they have on the web and I added one more iteration just to see what it would do, I have the file somewhere on another computer I will post it as soon as I can find it, it may take a while that other computer hasn't been on for a year.I used corel draw to design it and etched it using toner transfer, I have a pile of double sided pcb boards I got off of ebay so it was really cheap.
Ethernet Auto-negotiation & Signal integrity - Page 1
Forum section: electronics / projects

author: michaelym
author_rank: Regular Contributor
timestamp: March 12, 2020, 04:27:25 am
content: So I understand that "Auto-negotiation" is based on the capability of the end devices. So for example, if they both can do GBE the link will be GBE. What happens if there are signal integrity issues on the line between them. Do they just "struggle" with many lost packets or do they automatically reduce to 100.

author: tooki
author_rank: Super Contributor
timestamp: March 12, 2020, 04:42:24 pm
content: Doubtful. GbE uses all 4 pairs in the cable, as opposed to 100Base-TX which uses only two. In essence, it’s two 500Mbps links aggregated. So chances are that degraded half-gigabit times two is better than dropping to a single 100Mbps, at least if the links half work.(Just to be clear, this is pure speculation on my part. I haven’t done any testing or anything.)

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 12, 2020, 05:42:07 pm
content: Quote from: michaelym on March 12, 2020, 04:27:25 amI know very little about wired/wireless Ethernet technology, but from what I know it tend to work as GBE with a big loss of packets (up to 100% loss).Auto-negotiation is more about device capabilities (exact as you stated), but not about channel capability. It quarantining to work 10/100 MBE devices with 1/10 GBE devices together in different variations, but it is not about physical channel testing.I don't know, may be there is "improved" Auto-Negotiation Technology where each device can test it's physical connection to other device, and "pretend" lower-speed device. But I haven't heard about that.

author: ve7xen
author_rank: Super Contributor
timestamp: March 12, 2020, 08:15:40 pm
content: Autonegotiation is, as you suspect, capability negotiation and not training / based on the signal integrity conditions whatsoever. In fact, since autoneg occurs over the two 'normal' pairs (used in 10base-T and 100base-TX), it's possible to successfully negotiate 1000base-T even if the other two pairs are completely missing, and the link will be completely nonfunctional. Some PHYs do include cable tests / TDR measurements, but this isn't generally done routinely before link-up, and isn't standardized or part of the autonegotiation process.QuoteNot quite, all 4 pairs are used bidirectionally in 1000base-T; it's actually 250Mbps x 4 (same 125Mbaud as 100base-TX). Also the line coding splits each byte across all 4 channels, so if you lose any of them, the link won't pass any data at all. Even if it did, higher level network protocols would tolerate 50% packet loss extremely poorly, and real-world performance would be much, much, much worse than a properly working 100mbps link (it would be essentially unusable).Due to improvements in line coding, the use of bidirectional channels, and adding more pairs, the signal quality requirements for 100base-TX and 1000base-T are basically the same, so as long as the extra pairs aren't damaged, it shouldn't generally have a different error rate than 100base-TX on the same cable.
Ethernet Capacitive Coupling Design and Layout? - Page 1
Forum section: electronics / projects

author: sddsfgadasd
author_rank: Newbie
timestamp: December 07, 2022, 02:05:28 pm
content: Hi all, has anyone got an example of a PCB layout which uses capacitive coupling instead of discrete magnetics when connecting ethernet from a cable to a generic PHY? I was thinking of following an approach like thishttps://wiki.analog.com/_media/resources/eval/user-guides/adin1300-and-adin1200/tvs_and_cmc.jpg?w=600&tok=55ed1b.1. Do you need Bob Smith termination on the connector side to the chassis as you would with discrete magnetics?2. Do you need to have a keepout plane on all layers underneath the connector to the capacitors?3. Do these capacitors need to have HV specifications?

author: jonpaul
author_rank: Super Contributor
timestamp: December 07, 2022, 04:38:53 pm
content: Ethernet 10baseT..100Baset, ghz requirements include transformers for CMRR and to break ground current loops.Use in telecom, broadcast, pro audio and pro cinéma all use the transformersSee the PHY IC mfg app notes and eval bds.Depending on the requirements, EMI and transient susceptibility and environmental you can certainly try your scheme but 8t will not be Ethernet.The transformers are available in single..dual, quad a etc in DPI and SMD packageSome RJ45 have the magnetics built in.Suggest that you read the Ethernet PHY standard and specs for the desired baud rate.Bon chanceJon

author: langwadt
author_rank: Super Contributor
timestamp: December 07, 2022, 05:33:31 pm
content: is it worth risk if you need an rj45 anyway and can get those with build in transformers?

author: Siwastaja
author_rank: Super Contributor
timestamp: December 07, 2022, 05:38:08 pm
content: You had another thread about ethernet but it did not go further into your design.Are you 100% sure you want to go to such special snowflake design? What is the reasoning for wanting to do capacitive isolation instead of the usual transformer thing? With transformers, you have plenty of off the shelf components and reference designs which are tested and used everywhere.From your 3rd question I also deduce you are probably fine with the usual 1kV or so functional isolation provided by the usual ethernet transformers.

author: oystein
author_rank: Newbie
timestamp: June 09, 2023, 09:00:53 pm
content: Read this application note from microchiphttps://ww1.microchip.com/downloads/en/Appnotes/ANLAN120-UNG.pdfI am doing a design now with 5 port embedded ethernet switch KSZ8795, one port will have a RJ45 with integrated magnetics for external cable connection, all other Ethernet units connecting to the other ports only need capacitive coupling as shown in figure 3 as long as they implement 10BASE-T/100BASE-TX PHY layerBut it will not work with capacitive coupling above 100mbit or for long distance, only shorter distances with lower speedNot 100% sure, but at least this is my uncerstanding at the moment, I will post a reply after testing with diffferent ethernet devicesKind regardsØystein
Ethernet: Leaving float the "bob smith terminate" of Integrated Magnetics  - Page 1
Forum section: electronics / projects

author: ixps
author_rank: Newbie
timestamp: December 10, 2021, 01:59:16 am
content: Hello peoples!I'm designing a PCB that uses an Ethernet Connector (integrated magnetic of Pulse Electronics) and I'm having troubles because my PCB its very small and I have constrained space to route the traces / vias and etc.So I'm considering to leave floating the "Bob Smith" termination of Ethernet Connector, but my application it's industrial and I can't have any issues in future because the product need to be robust.Could anyone tell me if it's a problem? I read that it is confuse subject (each person said any thing).Thanks.

author: spostma
author_rank: Regular Contributor
timestamp: December 14, 2021, 11:06:45 pm
content: the Bob Smith termination is intended to provide both common mode and differential mode termination.If you leave the capacitor ungrounded then the common mode termination will be absent,and you may expect a raised EMI and reduced immunity, so your CE test probably will fail.rather than leaving the capacitor ungrounded, I would start searching for one in a form factor that better fits your available space.
Ethernet link detection - Page 1
Forum section: electronics / projects

author: rakeshm55
author_rank: Regular Contributor
timestamp: November 12, 2019, 08:49:27 am
content: Hi,Assuming1. A generic 10/100 Ethernet PHY2. Using the general purpose registersWhat is the logic used by controllers to detect link from an Ethernet PHY. Do they keep on polling the link up bit from the register set??If so How frequent do they poll this register via MDIO??Is there any literature or code snippet (C code ) for this ??My purpose is to use FPGA (vhdl) to detect link up/down from an Ethernet PHY.As I understand there are PHY dependent features like interrupt, but I would like to stick with general purpose registers. Once the approach is clear i can hand code vhdl for this purpose. So that FPGA an frequently keep track of link up and down status.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: November 12, 2019, 09:18:00 am
content: Quote from: rakeshm55 on November 12, 2019, 08:49:27 amYes.QuoteEvery 1..5 seconds.QuoteThe PHY register set is a standard (IEEE 802.3). You just have to check bit #2 ("Link Status") of the basic status register (that's register #1).

author: rakeshm55
author_rank: Regular Contributor
timestamp: November 12, 2019, 09:25:34 am
content: On more queryIf there is continuous Rx activity (receive data) then will it hold the polling loop?? or reset the timer ??or they just keep on polling no matter what activity in Data receive.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: November 12, 2019, 09:36:01 am
content: I think the driver keeps polling no matter what. When it sees lost link, triggers a renegotiation.
Ethernet PCB layout - swapping signals or pairs for easier layout - Page 1
Forum section: electronics / projects

author: daloev
author_rank: Contributor
timestamp: April 10, 2024, 06:51:08 pm
content: [edited to correct some information]I'm layout out a board with a Raspberry Pi CM4, so it is 1G Ethernet. A magjack with the tab on the bottom lays out easily, with no signals crossing, but I would like a tab on the top in my particular situation. Because the cable is oriented differently, the pinout on top-tab jack is the reverse of the pinout on bottom-tab jack, and now everything crosses. I believe that it is ok to swap certain signals to make the PCB layout easier, and I would like to review what is possible.Swapping + and - within a pair is ok. A Microchip article (https://microchip.my.site.com/s/article/Can-the-Ethernet-transformer-pairs-be-swapped) says polarity detection and correction is standard in PHYs these days.Is swapping entire pairs ok with certain limitations? Suppose a connector has this layoutPCBCablePin 1: TD1+J1: TX1+Pin 2: TD1-J2: TX1-Pin 3: TD2+J3: TX2+Pin 4: TD2-J6: TX2-Pin 5: TD3+J4: TX3+Pin 6: TD3-J5: TX3-Pin 7: TD4+J7: TX4+Pin 8: TD4-J8: TX4-A crossover cable exchanges TD1 and TD2, and may exchange TD3 and TD4, so those swaps are fine. Exchanges between those 2 groups (e.g. TD1 with TD3) will mess up auto negotiation. If you do such a swap and manually set the speed to 1G on both ends so you don't need auto negotiation, would gigabit Ethernet still work?I don't need PoE, but how would PoE affect it? From Wikipedia (https://en.wikipedia.org/wiki/Power_over_Ethernet), it looks like swapping pairs or swapping signals within a pair would mess up 10/100 mode POE, exchanging DC+ and DC-. However, ajb says decent POE implementations have a diode network to handle any combination of pair polarities, so PoE isn't a consideration when swapping signals or pairs.

author: ajb
author_rank: Super Contributor
timestamp: April 10, 2024, 11:59:30 pm
content: Link negotiation happens on the A (pins 1&2) and B (3&6) pairs, so those should not get swapped with the C and D pairs for that reason. Swapping A with B and/or C with D should be fine.Quote from: daloev on April 10, 2024, 06:51:08 pmAny decent PoE PD implementation should use an input diode network (a bridge rectifier for two-pair versions, or a pair of bridge rectifiers for four-pair versions) to handle any combination of pair polarities. That's independent of how the pairs are assigned at the PHY.
Ethernet PCB routing  - Page 1
Forum section: electronics / projects

author: AndrewHodgson
author_rank: Contributor
timestamp: March 19, 2020, 10:12:53 am
content: Hi,If I am using external magnetics, do people think it is a good idea to have a separate ground plane under the signal lines post transformer? I've had a look at some TI guidelines and they said don't put a ground plane under the signal lines between the transformer and the RJ45, but the Toradex routing guidelines seems to suggest it's a good idea.https://docs.toradex.com/102492-layout-design-guide.pdfpage 34.If i include the ground plane, which net should it connect to? At the moment I've got it connected to the termination plane, that is the point where all the bob smith termination resistors are connected. Then there is a capacitor connecting the plane to the shield ground.Ethernet is 100MBThanks

author: Daixiwen
author_rank: Frequent Contributor
timestamp: March 19, 2020, 12:24:32 pm
content: I don't put any plane under those lines and it works fine. If you use a plane then it must be the one that you are using right now ("chassis") and not your logic ground.At only 100 MB I don't think you'll see a huge difference anyway, especially with such a short distance between the magnetics and the connector.

author: AndrewHodgson
author_rank: Contributor
timestamp: March 19, 2020, 01:08:14 pm
content: Thanks! I'll probably just remove it then.In the Toradex guidelines the reference plane does look like it has been separated. That makes sense to me because presumably the signal lines need to be isolated from the shield/enclosure ground. If you rely on the PCB for the isolation, then i would have thought the distance between the reference plane and the signal lines would be quite large, meaning you need very large tracks to get the correct characteristic impedance.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 19, 2020, 06:38:28 pm
content: Use differential pairs, 100Ω, no ground plane. May not actually be able to achieve that within acceptable PCB limits (trace spacing), so just get it as close as practicable and keep the routed lengths short so the discontinuity doesn't affect it too much.Note that you can do edge-coupled differential on a single layer, buried edge-coupled (on an inner layer), or broadside coupled stripline (on top of each other, different layers).Tim

author: AndrewHodgson
author_rank: Contributor
timestamp: March 20, 2020, 08:24:41 am
content: Interesting, sounds like plan.Thanks guys! Much appreciated
Ethernet PHY connection problems - Page 1
Forum section: electronics / projects

author: hanwool
author_rank: Newbie
timestamp: October 30, 2021, 07:37:34 am
content: Hi, I'm newbie to hardware design.I make a ESP32 board connect to Ethernet using LAN8720A.My initial design is not successful..LAN8720A always report link down.I connect LAN8720A to ESP32 like Waveshare's module. but I using ESP32's APLL as RMII Refclk.REFCLK is looks fine as module's REFCLK on my prototype.49.5MHz to 50.5MHz, Mean 1.68V Vpp 2.4V Min 560mv Max 2.32v.Auto negotiation is failed. 10BASE-T mode is failed.This is signal when Auto negotiation enabled, unplugged LAN cable.This is plug in LAN cable when same configuration.My schematic and gerbers.My eagle board file is attached in end of my post.By My mistake, I lost original board design. some route is missing.I can't find out what the problem with my design is due to lack of knowledge.Can you share your wisdom?

author: hanwool
author_rank: Newbie
timestamp: October 30, 2021, 04:27:53 pm
content: I resolve my problem.Just my supplier's error.My design intent to use J1B1211CCD, But My supplier supply me J1B1211CFD.Hard wiring board to MAGJACK solve my problem.
Ethernet PoE module schematics - Page 1
Forum section: electronics / projects

author: SebDominguez
author_rank: Newbie
timestamp: June 15, 2018, 07:25:18 am
content: Hi!I’m actually working on my first home made module. It’s a Ethernet PoE shield for Arduino pro mini (I needed to shrink down my Uno prototype and since I could’t find any mini shields with PoE I decided to make my own).But since this is my first try I want to know if I am doing things right. this is why I'm asking for your precious feedbacks.Since Magjack connectors are black magic to me, I'm using a HY931147C connector since this is the same that Arduino CC used on they shield. As I understand, I can use this module for Passive and active PoE application since Pin 4, 5, 7 and 8 are rectified and exposed on v+ and v-. The module also expose RXCT and TXCT but I'll not use them since the PoE module that I'm using will not works If I use both power options and I wanted my module to be compatible with passive PoE with inexpensive injectors.Link to PoE module :https://www.arduino.cc/en/uploads/Main/PoE-datasheet.pdfLink to RJ45 connector :http://www.knap.at/datenblaetter/ste/ste_han_hy931147c.pdfI’m using a W5100 chip. I followed they « reference schematic » but In another document (Layout guide) they say things contradictory to the first document. For instance : in the reference schematic they use 3 different Ground (Chassis completely isolated, Digital ground and analog ground) and in the layout guide they said « It’s better that do not try to partition ground ».Link to the W5100 hardware design guide :http://www.wiznet.io/wp-content/uploads/wiznethome/Chip/W5100/Hardware/w5100_hardware.zipSo before I’m starting the PCB design, can somebody told me if I’m doing something horribly wrong?Do I need to replace all analog ground reference with digital ground ? Do I need to keep the RJ45 shield isolated? If yes : How to I draw my isolation area? (In the layout guide the RJ54 is separated from the magnetics, but my connector has integrated magnetics so how can I do that ?)Thanks a lot everyone !Edit:Since the AG9000-S series is really hard to find I've changed my PoE module for a PEM1203 that use the same footprint but a slightly different configuration. It's also possible to use this module with both Mode A and B PoE so I hope I've wired up correctly RXCT and TXCT with the module.Edit 2: I forgot the bypass caps...
Ethernet routing 2 components on same board - Page 1
Forum section: electronics / projects

author: AndrewLoomis
author_rank: Contributor
timestamp: March 25, 2018, 06:26:02 pm
content: Two components I am working with communicate over an ethernet LAN, and I am planning on integrating them on the same board. Normally, I have used RJ45 connectors with integrated magnetics to connect 2 ethernet boards over a cable, but with this board, there is no cable. I am guessing that I still have to use discrete magnetics on-board between the two components, but I wanted to confirm if this is the right method.

author: cowana
author_rank: Frequent Contributor
timestamp: March 25, 2018, 06:46:31 pm
content: If you don't need the isolation requirements provided by magnetics, you can get away with capacitive coupling if PCB area or BOM are important to you.Have a read of these application notes for more information:AN-1519 DP83848 PHYTER Transformerless Ethernet OperationCapacitive Coupling Ethernet Transceivers without Using Transformers

author: ajb
author_rank: Super Contributor
timestamp: March 25, 2018, 06:54:32 pm
content: If you've got two PHYs you can capacitively couple them as cowana suggests--search for "transformerless ethernet" or "ethernet capacitive coupling", there are plenty of appnotes. If both devices expose MACs, depending on the devices and the board structure, you might be able to connect the MIIs directly, or you could integrate a switch IC with the appropriate MII ports. The latter could be a good way to go if you have to tie those two devices to the outside world as well.

author: AndrewLoomis
author_rank: Contributor
timestamp: March 25, 2018, 06:58:20 pm
content: Thanks! Those app notes were exactly what I'm looking for, the capacitive coupling is definitely more BOM efficient than the transformers. I guess I just wasn't searching for the right thing.
Ethernet skew data pair - Page 1
Forum section: electronics / projects

author: cheeseburger
author_rank: Contributor
timestamp: March 05, 2025, 09:50:30 pm
content: Does matching the skew between different data pairs provide any advantage, or could it even degrade the signal? Intra-pair skew matching makes sense, but I’ve never seen a requirement for matching skew between separate data pairs if it doesn't exceed like tens of millimeters.This is specifically for 1000BASE-T/100BASE-T—nothing more advanced.

author: aeg
author_rank: Regular Contributor
timestamp: March 06, 2025, 01:15:12 am
content: Ethernet cables have a different turns ratio for each pair, to reduce crosstalk. So the cables have as much as a few tens of nanoseconds skew between pairs. An additional 1 or 2 nanoseconds of skew from your PCB layout won't make a difference.
Ethernet Switch ICs - Page 1
Forum section: electronics / projects

author: WelshDave
author_rank: Newbie
timestamp: November 25, 2020, 03:47:46 pm
content: I've never worked with Ethernet switch ICs but have need for one in a design.An unmanaged switch seems to be the simplest to implement.I've looked at ICs available on Farnell in the UK and they only have managed switch ICs.Can anyone help with a reliable source for Ethernet switch ICs, ideally an unmanaged switch?Any tips for devices containing switches would also be welcomedDave

author: WelshDave
author_rank: Newbie
timestamp: November 25, 2020, 04:16:12 pm
content: Ok.That's good and means I'm not as far off course as I thought I was.I have identified 3 part numbers but all only seem to be available through eBay in China but all were Realtek.Thank you!

author: girishv
author_rank: Regular Contributor
timestamp: November 25, 2020, 04:25:51 pm
content: Quote from: WelshDave on November 25, 2020, 04:16:12 pmMicrochip has many Ethernet switch products.Checkouthttps://www.microchip.com/design-centers/ethernet/ethernet-devices/products/ethernet-switchesThey come with pretty decent documentation. Probably you can get free samples too.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 25, 2020, 09:55:11 pm
content: The extra silicon cost to make a switch managed is low enough that it doesn't make sense to make a chip specifically for unmanaged switches.http://spritesmods.com/?art=rtl8366sb

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 26, 2020, 10:10:53 pm
content: A simple search like:https://html.duckduckgo.com/html?q=open+source+ethernet+switch+projectshould get you plenty of suggestions.
Ethernet termination - bob smith for Board to board connection - Page 1
Forum section: electronics / projects

author: rakeshm55
author_rank: Regular Contributor
timestamp: September 12, 2019, 10:54:53 am
content: Hi,I have a 10/100 Eth running from one board to another via board to board connectors not standard Eth ports (RJ45 connectors)Here I use Magnetics at both the boards.Eth PHY1 (board 1)----> Magnetics (board 1)-<---Board to board Connector----> Magnetics (board 2)-<-------- Eth PHY2(board 2)How to handle this bob smith termination to chassis ground. Here there is no chassis GND involved . Please advice.
Ethernet to Ethernet without magnetics - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: February 17, 2021, 02:58:52 pm
content: Hi,Whenever I designed using Ethernet I always used included the required magnetics. But because of a very tight enclosure they are too big and there would not be enough space for the connectors between the two PCBs.So I was wondering whether it is possible to connect two Ethernet devices/ICs directly to each other by removing the magnetics on both sides?If so, is it as simple as that or are there special considerations or special cases that need to be carefully addressed?Thank you as usual!

author: ajb
author_rank: Super Contributor
timestamp: February 17, 2021, 03:15:48 pm
content: Sure: you can capacitively couple a pair of PHYs without magnetics. Here's one appnote on the subject, there's a lot more material or there:https://www.ti.com/lit/an/snla088a/snla088a.pdf

author: TheMG
author_rank: Frequent Contributor
timestamp: February 17, 2021, 05:18:14 pm
content: You can absolutely do away with the magnetics if you're only connecting between two PCBs within the same device. It's actually pretty common when for instance connecting between PCBs on a common backplane, or even between ICs on the same PCB.Assuming you're not using RJ45 connectors? If you are, they do make them with integrated magnetics that are really not much larger than a plain jack.

author: ricko_uk
author_rank: Super Contributor
timestamp: February 17, 2021, 05:26:38 pm
content: Thank you Ajb and TheMG
Ethernet to RS485 widget - Page 1
Forum section: electronics / projects

author: funkyant
author_rank: Unknown
timestamp: March 11, 2019, 02:20:43 pm
content: I've never started a project like this before, but I really have a need for a specific widget which after some years, is still not available to purchase from any manufacturer at any cost. So I figure it's time to jump in and try to design one.Trouble is I'm not sure exactly where to begin.Design goal as follows:ArtNET to DMX adapter.IP67 rated or near as possiblePoE power supplyArtNET is an open source protocol supported by many (most) lighting control manufacturers.https://en.wikipedia.org/wiki/Art-NetDMX is a variant of RS485 and is still the main standard for professional lighting fixture control, but is slowly being replaced by ArtNEThttps://en.wikipedia.org/wiki/DMX512The max485 chip seems to be the standard for sending DMXhttps://www.maximintegrated.com/en/products/interface/transceivers/MAX485.html/tb_tab0Data rate of a single DMX universe (bus) is 250kb/s. I'd like my widget to have 4 output bus, so total data rate of the MPU needs to handle 1Mb/s without issue. Existing (non PoE, non waterproof) products on Aliexpress suffer from jamming up when dealing with too much data throughput, so I'd like to improve on that.Where I'm getting a bit lost is where to begin looking for a suitable microcontroller. It would need to run an 100mb ethernet stack, a simple web server for remote settings management, the ArtNET library to read the data packets and spit them out to the max485 chips. And then I need to design a power supply that will work with off the shelf PoE ethernet switches.The mechanical design, I'm planning on borrowing from a great MPPT solar housing I saw which is basically perfect for keeping everything weatherproof, whilst easily serviceable.Can anybody point me in the right direction with regards to the PoE part and a suitable MCU/ MPU?There are projects around using Raspberry Pi and even Arduino, but the former is overkill, and the latter also lags when flooded with a lot of data.Competing products are priced at around 300 bucks a pop, and require a power supply and require mounting in a weatherproof box. I need 5 for a current project and am happy to go through a learning curve to create the perfect solution to my problem of reliably controlling outdoor lighting, which is not a unique problem to me.
Ethernet to Serial Board Mountable Modules - Page 1
Forum section: electronics / projects

author: gnuarm
author_rank: Super Contributor
timestamp: December 02, 2022, 02:35:36 am
content: Frustrated with the limited functionality of USB and Ethernet to serial port adapters throughput, I'm finally ready to consider putting an Ethernet to serial adapter on each of my test fixture boards and letting the PC address them separately. Hopefully the delays on the Ethernet bus won't impact the message exchange protocol in the same way it does with one serial port handling all the comms.So I've found a few devices, but the vendors are not very familiar to me. A pricey source is Moxa, with some pretty small modules, for over $50 each. They are also hard to find.https://www.moxa.com/en/products/industrial-edge-connectivity/serial-device-servers/serial-embedded-modules/miineport-e2-series#specificationsAnother is Wiznet, which seems to have a very clumsy web site. The Wiz750SR seems to be what I would use. These are about twice the size and they give virtually no information I can find on how they might mount on your board. In fact, they seem to be saying this module is only for use on their EVB Board. They include lots of 2D images from a 3D view, but nothing with info on how to actually connect this to a motherboard. I guess you invert it and use sockets. The pins are all to the upside. The module's height will make it hard to mount in the 0.8 inches I was planning to allow for height.These are about half the price of the Moxa devices and stocked at Digikey and Mouser.https://www.wiznet.io/product-item/wiz750sr/Anyone have experience with these devices? Any comments?
Ethernet TTL Direct Connection - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: April 17, 2020, 05:22:51 pm
content: Hi,is it possible to connect 2 micros on the same board to each other using Ethernet connection?Obviously placed only few mm apart from each other and obviously using matched length/impedances traces.If so then anything should I be aware or careful about in the design?Thank you

author: donotdespisethesnake
author_rank: Super Contributor
timestamp: April 17, 2020, 05:52:36 pm
content: By "Ethernet TTL" I guess you mean MAC to MAC, rather than PHY to PHY. I believe MAC connection is possible with a RGMII interfaces, can't say I've ever seen it done though.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 17, 2020, 05:55:28 pm
content: AFAIK, yes, you just need to swap the RX/TX lines much as you'd connect a UART. I haven't done it but I've ran across a few appnotes that seem to cover it.Tim

author: David Hess
author_rank: Super Contributor
timestamp: April 17, 2020, 09:37:54 pm
content: It is definitely feasible. Between boards or chassis where there may be a ground difference, the signals can be AC coupled.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 18, 2020, 01:03:07 am
content: Quote from: David Hess on April 17, 2020, 09:37:54 pmDo you mean MDI? Yes, that works, just use pullup resistors and coupling caps, no transformers needed -- or just the one transformer for better isolation than capacitors. (To clarify, coupling capacitors alone, works for small ground-to-ground offsets: maybe fractional volts at AC, up to say tens of volts at DC. Whereas the transformer gives very low isolation capacitance, allowing much more freedom at both AC and DC.)For MII, I don't know that it can be AC coupled?Tim

author: David Hess
author_rank: Super Contributor
timestamp: April 18, 2020, 11:50:01 pm
content: Quote from: T3sl4co1l on April 18, 2020, 01:03:07 amI mean for MDI and there are application notes discussing it.
Ethernet/PoE Class 2 SPD (surge protection device) - Page 1
Forum section: electronics / projects

author: Fflint
author_rank: Frequent Contributor
timestamp: June 06, 2024, 01:06:29 pm
content: I've been recently looking for a PoE 100Mb capable Ethernet class 2 SPDs, but manufacturers of said devices are taking the piss with prices (asking for $100 for $5 woth of parts).So I'm thinking of rolling my own. I've used GDTs in my designs before. Also one can buy TVS diode arrays for Ethernet surge protection. What I can't find is:- What is the acceptable capacitance on signal lines for 100Mb Ethernet (I'd like to add varistors)- Does anyone know Mouser/Farnell part numbers for the PCB mouted push in ethernet cable connectors (like ones used in patch panels, made by Krone and others)Finally, is anyone aware of open source projects like this? Or schematics online? 100Mb tech is pretty old so I'd think they would be plenty. I found only one that had max current of 3A (I'd like at least 7A, prefferably few dozen A).Maybe someone has got a DIY project they want to share, or you have some tips?I prefer push in cable connectors than rj45. This is why I'm asking for these.
ETI Bicycle Speedometer January 1988 - Triplexed LCD Available? - Page 1
Forum section: electronics / projects

author: Chris56000
author_rank: Frequent Contributor
timestamp: October 24, 2017, 05:49:56 pm
content: Hi!In my pushbike days I thought of building the Bicycle Speedometer published in ETI January 1988 which used an ICM7231 Triplexed LCD Driver chip (Maxim's device is still obtainable) - but I've had no luck finding the 8 Digit Triplexed LCD with Annunciator Arrows this used!Does anyone know if this 8 Digit Triplexed LCD can be found anywhere?(There's a Project Book somewhere on American Radio History with this project I believe!)Chris Williams

author: Ian.M
author_rank: Super Contributor
timestamp: October 24, 2017, 06:21:30 pm
content: If you've got an image of the LCD layout, post it, you might get lucky, but its probably best to do a ground-up redesign. 2.13" and 3" SPI interface eInk display modules are readily available, then its just a matter of wheel sensor, a low power MCU - whatever your favourite one is, or an Arduino or an AVR using the Arduino toolchain if you don't have a lot of embedded programming experience, some waterproof buttons, a LiPO cell and a battery management IC.An alternative if you are more into programming would be to give the wheel sensor a Bluetooth interface, and implement a bike computer as a Android app on a phone in a waterproof bike mount case. Some commercial products already do this, but there's nothing to stop you designing one with comparable features and performance.

author: Andy Watson
author_rank: Super Contributor
timestamp: October 24, 2017, 06:22:58 pm
content: 8 digit displays are still available - not sure about the annunciator arrows - do you have a part number for the display?http://tinyurl.com/y73r2n5c

author: Chris56000
author_rank: Frequent Contributor
timestamp: October 24, 2017, 06:36:03 pm
content: Hi!Pages 4-11 of this:-http://www.americanradiohistory.com/Archive-Electronics-Today/Electronics-Today-1988-Top-Projects.pdfThe LCD is given as Farnell 175-595 but that p/n's been dead for innumerable years!I do remember there were some of the early electronic digital pre-pay meters used this LCD but I've not been able to find a type no. for the LCD itself!Chris Williams

author: Andy Watson
author_rank: Super Contributor
timestamp: October 24, 2017, 07:24:29 pm
content: I miss ETILooks like you want the DE133 version (pick LCD tab then 7-segment panels):http://www.display-elektronik.de/If you search "LCD DE133" there are several sources, like:http://tinyurl.com/y7tshqaqOr even ebay.

author: Ian.M
author_rank: Super Contributor
timestamp: October 24, 2017, 08:20:14 pm
content: Its still not worth doing a retro build of it, (4 chips to implement the MCU + entering and checking EPROM dumps in HEX) although finding a source for the LCD does bring the option of a redesign based around a PIC or AVR with an integrated segment LCD controller, which would remove the need for the ICM7231 and get it down to only one chip.
EUREKA  !!  LED tester with zero cost ..    - Page 1
Forum section: electronics / projects

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 02, 2010, 08:23:54 pm
content: Everything started when I took my old RS diode- transistor tester apart for cleaning , actually total wash and replaced the 9V battery too ...As soon it become active again... I took an LED at hand, to test the functionality , the LED under test started flashing , no matter the polarity ..This gave me the idea that the LED could possibly light on , also with the on board transistor tester ,on my DMM ... and it did, the voltage output are about 3V , so yes it can work out..Check out the pictures ... emitter and collector.