hybridfree/eevblog-posts huggingface dataset:
Tutorial, Experiment & Teardown of a 24GHz Doppler Radar Module - Page 1
Forum section: electronics / projects

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 13, 2018, 03:45:14 am
content: In this episode Shahriar demonstrates a full analysis of a CDM324 24GHz Doppler radar module from IC Station. Opening the module reveals a series of microwave PCB components and several active devices. A complete analysis of the module is presented. The unit is then measured and the impact of antenna impedance and power supply voltage on the output frequency is measured. The phase noise of the output signal is also measured. Using a series of servo motors, the radiation pattern of the antenna array in both azimuth and elevation is also presented.Using the radar module the speed of a computer fan is remotely measure using an oscilloscope and FFT function.All proceedings from Patreon for this video will be donated.You can watch the video here: [40 Minutes]youtu.be/5vqSX40seqAMore videos at The Signal Path:http://www.TheSignalPath.com

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 13, 2018, 02:46:09 pm
content: Forgot to link the module:http://www.icstation.com/cdm324-24ghz-microwave-human-body-motion-sensor-module-radar-induction-switch-sensor-p-8962.html
Tutorial, Experiments & Teardown of a 77GHz Automotive FMCW Radar Module - Page 1
Forum section: electronics / projects

author: Hugoneus
author_rank: Frequent Contributor
timestamp: May 29, 2017, 02:28:16 am
content: In this episode Shahriar explores the principle operation of automotive FMCW radars. Thanks to a donated automotive radar module, various components of the system can be examined and explored. The PCB reveals three die-on-PCB ASICs responsible for generating and receiving 77GHz FMCW signals coupled to a 2D array of antennas. Several microwave components such as rat-race couplers and branchline couplers can also be observed. PCB rulers from SV1AFN Design Lab (link below) also show these microwave components at much lower frequencies. Two other ICs are used for ramp generation and PLL as well as a multi-input LNA/PGA/AAF with 12-bit ADC for IF processing. All components are examined under the microscope and the frequency of operation is calculated by measuring the branchline coupler's dimensions.Finally a simple Doppler effect radar is constructed by using a doubler, power divider, mixer and a pair of Vivaldi horn antennas. The Doppler effect can be observed by moving an object in front of the antenna pair.You can watch the video here: [27 Minutes]youtu.be/8af9YVIqhRkGet your microwave ruler here:https://www.sv1afn.com/pcbruler.htmlThe Signal Pathwww.TheSignalPath.comwww.YouTube.com/TheSignalPathwww.Patreon.com/TheSignalPath

author: sp2ipt
author_rank: Newbie
timestamp: May 29, 2017, 08:58:26 am
content: Am I missing something or did Shahriar forget to terminate the coupler with a load?

author: coppice
author_rank: Super Contributor
timestamp: May 29, 2017, 10:46:42 am
content: In the video Shahriar talked about the chip on PCB approach being used for cost reduction, but surely its mostly because packages limit performance so much at 77GHz.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 29, 2017, 11:58:03 am
content: Very nice video!I have one of these in my car and always wanted to know more details.You have a very good way of presenting your amazing knowledge.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: May 30, 2017, 02:43:43 am
content: Quote from: sp2ipt on May 29, 2017, 08:58:26 amDoh!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: June 01, 2017, 04:06:55 am
content: Quote from: coppice on May 29, 2017, 10:46:42 amYou can make a package that works at 77GHz fairly easily, it just won't be very cheap...

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 01, 2017, 04:05:34 pm
content: Too bad they didn't send what remains of the broken board, as it would have some interesting DSP hardware on it, maybe even still valuable if it's a high end FPGA that's still intact. (Maybe that's why?)

author: coppice
author_rank: Super Contributor
timestamp: June 01, 2017, 04:14:37 pm
content: Quote from: NiHaoMike on June 01, 2017, 04:05:34 pmThis is a consumer product, not some exotic piece of military technology. Whatever is on the other board, its something reasonably priced.
Tutorial on the effects of input filter using Dr. Vatche Vorperian Model - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: January 02, 2013, 11:40:26 pm
content: Short follow up video showing a model developed by Dr. Vatche Vorperian that can be used to see the effects of theinput filter on a power supply.Questions and comments are welcome.Robert
Tutorial on the effects that an input filter has on a switch-mode power supply - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: January 02, 2013, 06:55:25 am
content: Short tutorial videos on the effects that an input filter has on a switch-mode power supply.I used SPICE to show the effects and show how to fix the oscillation.Questions and comments are welcomed.Robert
Tutorial Video: Characterizing a Op Amp model. Part 1 - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: February 25, 2014, 03:16:13 pm
content: In this video, I show how to characterize the Open Loop Gain and Phase of an op amp model. This technique is useful to those who are designing op amps for school projects and to the experience engineer. When using op amp models from venders, it is always a good idea to verify the model. I have spent countless of hours on troubleshooting a design and it turned out that the spice model did not match the vendor's specification. So this is a good way of verifying your models.
Tutorial Video, Forward Converter Part 1, 2 - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: November 27, 2013, 04:32:07 am
content: This is the first part of a series of videos on the analysis, and design of a forward converter. In this first video, I first analyze a Buck converter because a Forward converter is a Buck converter with isolation. Therefore, the analysis applies to the forward converter. I show how to construct the "Ton" and the "Toff" circuit and derived two equations for the inductor voltage and use the Volt-Second rule to derive a transfer function. Questions or comments are welcomed.

author: rbola35618
author_rank: Frequent Contributor
timestamp: November 30, 2013, 05:03:15 pm
content: Part 2
Tutorial video, gain/phase of a flyback using a function generator and scope - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: June 15, 2013, 05:26:43 am
content: Poor man's frequency response analyzer(Gain and Phase measurement of a flyback supply)This video is a follow up to a previous video where I used a Venable Frequency Response Analyzer (FRA). Most FRA are out of the budget of most small business or hobbyist. However, you can use a function generator, an injection transformer, and a scope to measure the stability of a power supply such as a flyback.By injecting a signal and measuring the amplitude and the phase delay, you can measure three critical power supply specifications such as the crossover frequency, phase margin, and gain margin.You can use any wide band transformer as long as the transformer bandwidth is 1 MHz. The only negative of using an off the self transformer is that they have high capacitance from the primary to secondary in the 1.5 nF range. However, if you can wind your own transformer and use a split bobbing, you can greatly reduce the primary to secondary capacitance. The transformer that I wound measured a total of 15 pF between the primary and secondaryQuestion and comments are welcomed!

author: Tita
author_rank: Contributor
timestamp: June 15, 2013, 06:54:12 am
content: Good work..i like the video!

author: rbola35618
author_rank: Frequent Contributor
timestamp: June 16, 2013, 02:44:21 am
content: Thank you guys for the kind comments.Best regard,Robert Bolanos

author: Kevin.D
author_rank: Frequent Contributor
timestamp: June 16, 2013, 09:11:25 pm
content: A Nice (and rare) video demonstration of this technique ,thanks .Would of been better if you had discussed in more detail why you chose those specific values that you chose to use for the injection transformer and the injection resistor .But still really usefull ,even just to show people you dont need multi thousand dollar equipment to do basic stabiltity analysis .

author: rbola35618
author_rank: Frequent Contributor
timestamp: June 16, 2013, 09:30:33 pm
content: Kevin,That is great feedback. I will will anotate that on the video. One other thing that I forgot to mention is to make sure the signal level is increased until the sinewave starts to get distorded. The is suppose to be a small signal measurement. When the sinewave distorts, then you have too much signal and you are operating in the large signal mode.The injection transformer is a copy of the Venable injection transformer except that I used a bigger p-core. The capacitor should be a non polarized capacitor so the you can use it on both negative and positive supplies.I will annotate these facts on the video tonight. Again, thanks for the feedback KevinBest regard,Robert Bolanos

author: rbola35618
author_rank: Frequent Contributor
timestamp: June 17, 2013, 02:46:51 pm
content: I found an affordable FRA on the Cleverscope website. I think this is a game changer for those that are interested in a FRA. Most of the FRA out there cost from 5K to 35K. The Cleverscope is a fraction of its competitors at 1500. This is well within my budget.
Tutorial video: How to model a MOSFET using a datasheet  - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: August 07, 2013, 03:28:36 am
content: In this video I show a procedure showing how to extract a SPICE MOSFET model using a datasheet. The model is then confirmed by running a spice model to duplicate the family of curves to get a DC model. I then use the input, output, and reverse capacitance to extract the parasitic capacitance that dominate the AC model.Questions and comments are welcomed.
Tutorial video on design of an Input filter for switching power supplies - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: June 21, 2014, 03:20:43 pm
content: This video shows how to design an input filter for a flyback converter. I used the MIL-STD 461C as an example and show a procedure to calculate the component values and then show how to simulate the filter's performance. Questions or comments can be sent to rbola35618@aol.com
Tuya Cloud API - Page 1
Forum section: electronics / projects

author: davorin
author_rank: Unknown
timestamp: March 08, 2022, 08:48:38 am
content: Good morning (o;Someone ever used the Cloud API from Tuya?Reason for asking is:We have products using WLAN for connectivity in our own cloud and want to combine ZigBee products from the Tuya system into our cloud.Is that doable so we could control from our cloud our devices and devices from Tuya at the same time?thanks in advancerichard

author: Marco
author_rank: Super Contributor
timestamp: March 08, 2022, 06:42:50 pm
content: "our own cloud"No such thing.Look at Home Assistent's code? Though one look atthis pageconvinced me to continue never buying that fucking spyware bullshit.

author: davorin
author_rank: Unknown
timestamp: March 08, 2022, 07:16:56 pm
content: Well I know ;-)Over 25 years ago we called them just Sun Sparc running Netscape server software (o;But thanks for clarification....myself I don't like their eco system as well...just our mother company beingdesperate to have an add-on ZigBee product for cheap ;-)
TV out audio RC filter design - Page 1
Forum section: electronics / projects

author: jameswilddev
author_rank: Contributor
timestamp: February 15, 2021, 08:06:07 pm
content: Hello!I've been experimenting withhttps://github.com/rossumur/Arduinocadeand one of the things I'd like to improve upon is the audio. I've got a few devices and it works on all of them, but is very quiet.I've put a pocket DSO on the audio output and it seems to be a little low amplitude (600mV peak to peak) which roughly halves when a cable is connected (a breadboard was attached in both cases).Was the design here (100K resistor between PWM output and audio RCA jack) intended to form a RC filter with the cable acting as the capacitor?If so, could I replace this with something similar to the Pi's RC filter?https://hackaday.com/2018/07/13/behind-the-pin-how-the-raspberry-pi-gets-its-audio/There might need to be component substitutions as I'm running 5V here rather than the Pi's 3.3V, and the protection diodes can probably be dropped too (though if I do need it, I might want one on the video too). My system's mono so I'd only need one half of this.No real EE experience by the way, just poking components mostly. I would have posted in the beginners' forum but it appears to be having problems right now (502).Thanks!

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: February 15, 2021, 08:29:44 pm
content: Myguessis that the Arduinocade is relying on the inherent finite capacitance of the PWM output circuit.In the Pi case, the RC network is 270R and 33nF. To get the same RC constant with a 100K resistor, the capacitance would need to be 33 x 270/1000000nF = 89pF. A typical TTL pin has a capacitance of about 5pF. So, it's certainly within the realm of possibility that the use of the 100K resistor and the inherent pin capacitance will give a filter with a cut in the high 10s of kHz.I'd try the Pi version.
TV receiver wont turn back on with remote control - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: December 07, 2018, 06:28:08 pm
content: We've switched to a new "TV provider" and they installed a new TV receiver.The remote control to switch the receiver on and off works only to turn it on but since it's hidden away for aesthetic reasons, a small sensor is placed below the TV which can turn off the receiver but wont turn it back on.My question is how can I find a way to turn the receiver back on with the remote control without having to place it in the line of site of the remote control?Thanks!

author: cdev
author_rank: Super Contributor
timestamp: December 07, 2018, 07:44:03 pm
content: "TV provider" ? Literally?(Sounds like the sensor is powered from the TV so...)Did you ever get your noise issue sorted out?

author: Bud
author_rank: Super Contributor
timestamp: December 07, 2018, 08:57:15 pm
content: You can point the receiver behind the TV to the wall to the right or left from the TV or to the ceiling but may be hard to find a right angle and the remote also will have to be pointed to the same surface at an angle which may be awkward and work only from a certain position of the person in the room, anywa you can try, in a small room may be enough reflection from the walls to trigger the receiver.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: December 08, 2018, 12:03:16 am
content: Quote from: Bud on December 07, 2018, 08:57:15 pmProblem is the receive is tucked away behind a plywood wall so there's no way that would work.My previous receiver had a similar sensor placed below the TV and I could turn it off and back on with the remote control no problem not sure why this new service provider's receiver works differently.Can I hack it somehow? Also, for some reason the sensor has a bright red led thing going on and is powered by a usb port which can be very distracting in low light conditions. Maybe a new sensor is in order

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: December 08, 2018, 12:04:36 am
content: Quote from: cdev on December 07, 2018, 07:44:03 pmI meant to say service provider.You mean the noisy upstairs neighbours? No but the noise levels have been reduced to an almost tolerable level. Still looking for a place of my own
tvOne video switchers: Anyone with CC-300 controller? Pls help find commands - Page 1
Forum section: electronics / projects

author: Yansi
author_rank: Super Contributor
timestamp: April 27, 2020, 04:06:33 pm
content: Hello,I have tvOne video switcher from the C2-8000 series, but without any external controller. Control is possible from the front panel, although it is a bit annoying to use that way and some features are annoyingly hidden in deep menus and some functions are not accessible from there at all.I have found out, that there was a controller CC-300, that had the classic fader bar, that could control the transition manually (without a preset fade time). However the CC-300 is not (according to the tvOne support) compatible with the 8000 series switcher.I have compared the command sets from the user manual and both 7000 and 8000 series switcher command sets seems to be almost identical (same command codes and payloads), except a few extra commands in the newer 8000 series switcher, that the CC-300 likely does not care about anyway. So from my point of view, it indeed is compatible, at least with the commands that are listed in the manual. Of course there may be lot of others not listed.I am talking about these switchers: tvOne C2-8000 series (I got one), and C2-7000 series (for which the CC-300 controller exists).tvOne C2-8000 series switcher user manualand this controller console CC-300:tvOne CC-300 controller console user manual(If the links don't work, try locating the PDFs from here:http://tvone.crmdesk.com/faq.aspx)So I am interested if the CC-300 can or can't work normally with the 8000 series switcher. It seems it should?Anyway, I am also interested at what commands are sent to the switcher to manually control the transition (fader bar). Does anyone of you have access to the CC-300 controller, so we could maybe sniff it off the bus?Thank you for any helpY.
TVS Diode Array D+/D- Pins Reversible - Page 1
Forum section: electronics / projects

author: benwis
author_rank: Contributor
timestamp: July 29, 2016, 02:26:56 am
content: Hi,I'm laying out a TPD4S014 TVS array on my USB 2 Full Speed host, and I see in the layout section of the datasheet that the D- differential pin is connected ot the D+ input. The datasheet makes no mention of them being switchable, but I can't think of a reason they wouldn't be based on the schematic. Can anyone confirm whether it is okay to do this?EDIT: Put non existent part name in thereLink to Part:http://www.ti.com/product/TPD4S014

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 29, 2016, 05:44:53 am
content: Often, USB filter chips have pullup/down resistors inside, in which case polarity will matter.If it is as the diagram says, then no, it doesn't matter.Tim
TVS diode question.. - Page 1
Forum section: electronics / projects

author: MarkS
author_rank: Unknown
timestamp: May 29, 2023, 09:07:47 pm
content: The project I'm working on will require 6 TVS diode chips, in particular, theUSBLC6.The issue is that I have an odd number of signals. I have two from a USB connector, six from a microSD card and three from a SW debug connector. Is it acceptable to leave one input/output on the TVS floating? The datasheet doesn't mention this. I guess a single TVS diode would work best in this case, but I'm curious.

author: Benta
author_rank: Super Contributor
timestamp: May 29, 2023, 09:45:06 pm
content: No problem at all. It's just Zener diodes.

author: MarkS
author_rank: Unknown
timestamp: May 29, 2023, 09:51:24 pm
content: Quote from: Benta on May 29, 2023, 09:45:06 pmThank you! I figured, but wasn't sure and there's no point in implementing ESD protection only to sabotage it through ignorance.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 30, 2023, 02:25:26 pm
content: You can also double up on pins, when it's convenient. For example, routing USB through pins 1-6 and 3-4 to improve clamping just a little bit. (The USBLC6 is basically made this way by design, but there are 4-independent-channel types out there too.) Downside is it increases capacitance, so don't do it anywhere you need maximum bandwidth, or where you'd rather have symmetry (one pin per signal).Tim
TVS Diodes - Do they limit current or do you need a current limiting resistor? - Page 1
Forum section: electronics / projects

author: aiq25
author_rank: Regular Contributor
timestamp: December 04, 2017, 05:05:36 am
content: Hi. I was wondering do I need to have a current limiting resistor for TVS diodes? I always thought TVS diodes by design limit the current but recently I was told that was not the case.What I mean is... say I have a power supply capable of supplying 100's of Amps for few milliseconds at 25V. Should I include a current limiting resistor in my design to limit the current to say 10A max? Or less....

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 04, 2017, 09:14:03 am
content: Why is your power supply higher than the TVS diode rating in the first place?A TVS is just a zener diode. It has a low (incremental) resistance (at the clamping voltage). If you have a very low impedance source, like a power supply that's accidentally twice the voltage rating being hot-plugged, yeah, current limiting is required if you want to avoid damage.For transients, it's not usually required, but any impedance you can add of course helps.IEC surge has a source impedance of 2 or 20 ohms; fast transient and ESD have impedance 50-300 ohms (ballpark). This impedance, combined with the short duration of these transients, is how the bare diodes withstand such treatment.When the source voltage is high, things get more difficult. Say, mains transients: you have to deal with ~kV surges, but you can only clamp to maybe 400V because that's normal peak line voltage.Now, within a given family of TVS diodes, they all handle about the same power, whatever the voltage rating. So, high voltage diodes can't handle high currents.If you're clamping a 1.5kV mains surge to 400V, that's 1100V / 2 ohm = 550A peak. This may well be more current than hot-plugging a 48VDC supply into a short circuit!So the power and energy are much higher (~MW, and joules at a time) -- beyond what a mere TVS can handle (or an affordable one, at least).This is why MOVs are used for mains protection: way more energy capacity. Downside is, higher internal resistance. Which, yes, does reduce the surge current a bit -- but that makes it more difficult for your equipment to deal with what's left, because now the surge looks like a Norton source with a peak (clamping) voltage of, say, 800V and a source resistance of fractional ohms.If your risk scenario is different supply voltages, not induced lightning surge -- consider an overvoltage protection circuit instead. This is also relevant to automotive load dump (a very slow transient (~100ms) that therefore delivers tons of energy, maybe 10-100J), where shunting the surge is difficult.Tim
TVS for RS232  protection - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: April 24, 2020, 09:04:49 am
content: Hi,For RS485 I'm using PSM712 for ESD protection, For a new design that has a mix of RS458 and RS232 I want to select a TVS for RS232 protection, I came across these different PDF's from littlefusehttps://m.littelfuse.com/~/media/electronics/application_notes/littelfuse_tvs_diode_overview_application_note.pdf.pdfand bourns,https://www.bourns.com/docs/technical-documents/technical-library/chip-diodes/publications/bourns_tvs_diode_short_form.pdfBoth of them suggest different part numbers,Bourns would recommend SMBJ26CA and littelfuse recommend SMDJ15CASo which one should I choose? also do we have something more packed like two TVS in a single package, like PSM712?what do you recommend for RS232 protection?

author: chinoPR
author_rank: Newbie
timestamp: April 29, 2021, 01:59:46 pm
content: Hi men! well.. SMDJ series to littelfuse say "RS232 Interface Protectionwith High Surge Requirement" and support 3000W!...Bourns use SMBJ series and this type of TVS support 600W!The selection depend to your application designd and requeriments.. if you aren´t high specifications, use SMBJ (it´s more cheap)I hope I have helped you, greetings from Argentina
TVS selection guide - Is it wrong, or i am not comprehending? - Page 1
Forum section: electronics / projects

author: eTobey
author_rank: Super Contributor
timestamp: January 04, 2024, 02:56:53 pm
content: In the Manual it states:"For example, if the protected line operates at 5 V nominal with a maximum variance up to 7 V, ensure that the VRWM is 7 V or greater."So if i choose a Diode with 7V Vrwm, then the diode starts to really conduct just from lets say 7.5V in a ESD event. So that gives me a voltage, that exceeds the maximum values of 7V, wouldnt it?

author: tooki
author_rank: Super Contributor
timestamp: January 04, 2024, 03:37:07 pm
content: Sorry, what’s confusing you here?They’re simply saying “even if the nominal voltage (=Nennspannung) is 5V, if its signal normally can reach 7V even temporarily, then choose a diode with Vrwm above 7V”.The “variance” they mention doesn’t mean the absolute maximum value from the component datasheet; if your signal exceeded that, it would fry the chip even without ESD. A 7V signal would already be far outside the 5.5V absolute maximum of typical TTL, for example, but well within 4000-series CMOS logic.So if you’re protecting TTL with an absolute maximum of 5.5V, you’d need to choose a 5V TVS.

author: sparkydog
author_rank: Regular Contributor
timestamp: January 04, 2024, 06:28:24 pm
content: As noted, "maximum variance" is talking about your maximumnormal operationvoltage, as in, you don't want the TVS mucking with this. A TVS should never conduct under normal input voltage. A TVS is not intended to be used as a voltage regulator, and doing so can damage it prematurely because they are not meant to conduct continuously.(That said, note that it's not unusual to use a TVS to "eat" inductor spikes e.g. from relays / solenoids. Although thatis"normal operation", it isn'tcontinuousconduction because the spikes are brief.)Quote from: tooki on January 04, 2024, 03:37:07 pmUh... if your nominal voltage is 5V and 5.5V releases the magic smoke, I don't think a TVS is going to work. Now, to be sure, SMBJ is a commodity TVS and maybe more "sensitive" TVSs exist, but a 5V nominal SMBJ has a breakdown voltage (VBR) rating of 6.40V - 7.00V and a maximum clamping voltage (VC) of 9.2V. Say goodbye to your TTL.Personally, if I'm using a TVS to protect something, I try to arrange for itsVCto be around 60-70% the max voltage rating of the device it's protecting. (For example, I have designs that use SMBJ18s with components rated for 48V.)
TVS/ESD Diode on VBUS Line USB C - Page 1
Forum section: electronics / projects

author: OneGeekGuy
author_rank: Regular Contributor
timestamp: February 12, 2025, 09:28:58 pm
content: Hi everyone,I was using some time ago the famous USB PD controller STUSB4500. I am designing another PCB this time with another controller and I wanted to explore another alternatives for ESD/Surge/Lighting protection. While I was checking what I need, I went again to the recommended schematic for the STU and they recommend using ESDA25P35 for the VBUS line.If we take a look at the IEC6100-4-5, we see and unless I am wrong, that line to ground testing, level 2 is 2kV, considering a surge resistance of 42Ohm, this results into max Surge current of 47A aprox.The STUSB4500 has an absolute max voltage on VDD of 28V.If we take a look to the TVS datasheet, we would see that Vcl at Ipp of 35A is 41V.Then this means that during the pulse, the max voltage the VDD pin will see for a short time will be 41V. Is this correct? Would not be better to reduce the Vcl getting a diode with lower Rd, or I am being too conservative?Thanks and regards!
TVS/ESD protection on VBUS of USB for an industrial device - Page 1
Forum section: electronics / projects

author: electroro
author_rank: Newbie
timestamp: July 12, 2021, 04:24:06 pm
content: Hello folks,I am designing a device which will be used in an industrial setting like factories, offices, etc. It has a LiPo battery charger circuit in it. See attached image.The device does not use the USB data lines, only the VBUS is used to charge the LiPo. I am stuck at selecting a TVS diode.1) Do I need a TVS diode?2) What specs should I be looking for? Especially the working voltage and clamping voltage.- Can the working voltage (Vrwm) be 5V like in SMBJ5.0CA or ESD9101P2T5G or should it be >5V since some supplies may have 5.1V VBUS.- What clamping voltage is appropriate? Does it strictly need to be below Absolute maximum ratings of the devices?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 12, 2021, 05:25:43 pm
content: I would only worry about inrush surge and possible ESD strikes. No need for huge ratings or anything, not even an SMAJ should be needed I think.Inrush surge is mainly a current thing, but it can become quite substantial voltage when combined with the nonlinear dielectric of type 2 capacitors (C5, C6).The linear case, with no resistance and zero initial conditions, is an inrush current equal to Vin / sqrt(L / C), and a peak voltage of 2Vin; where L is the loop inductance (mostly the cable, ca. 0.5uH per m length), and C is the total input capacitance. The voltage peak is somewhat lower with ESR of course, and further ringing is dampened.The nonlinear case, where C decreases with increasing V, allows the peak to rise much higher, often over 3Vin. How much, depends on the C(V) curve of your chosen parts; you'll have to go digging for the char sheets, if they provide them at all. Also, hopefully you'll check for reasonably nominal value at operating voltage; 1uF 0603s being say -50% at 5V (regardless of voltage rating) is not uncommon. 0805+ should be fine, but do check as they can always skimp on the internals, the only thing you're really guaranteed is a too-small part won't hold enough charge.So, for these cases, having a TVS to clamp the peak, and an LDO rated for the clamped peak, is a good idea. Typically a TVS rated for nominal operating voltage (i.e. 5V) will clamp around 30% higher, or maybe worse I guess at lower voltages (I'd expect 8V here?). So a 10V rating for those parts should be adequate.Tim
TVSS diodes in series - Page 1
Forum section: electronics / projects

author: Seekonk
author_rank: Super Contributor
timestamp: December 03, 2017, 10:34:19 pm
content: I have to order a few P6KE68CA TVSS diodes and figured I might as well get a large lot. Any real downside to putting several in series so I can use them for other applications? Any need to balance them?

author: David Hess
author_rank: Super Contributor
timestamp: December 04, 2017, 01:51:55 am
content: They will work fine in series.
Tweaking the tuning of second-order state-variable bandpass filters - Page 1
Forum section: electronics / projects

author: stevebyan
author_rank: Contributor
timestamp: April 17, 2020, 07:39:56 pm
content: I'm trying to clean up the harmonics from our AC power line to feed a pure 60 Hz sine wave to the external reference input on my HP 6920B meter calibrator. I've designed a fourth-order Butterworth bandpass filter implemented using two second-order state-variable bandpass filter sections. So far so good.The piece that I'm missing is information on how to tune each section of the filter once it's been constructed. There are two adjustments per second-order state-variable section. Lancaster's Active Filter Cookbook is silent on this subject, as is my copy of Williams and Taylor's Electronic Filter Design Handbook. I'll be using 5% polystyrene capacitors I have on hand. I plan to make the frequency-controlling resistances tweakable, to compensate for variations in the capacitance. But how do I know what direction and how much to tweak?I wrote some code in theRacket programming languageto generate root-locus plots of the second-order state variable filter as the values of resistors R1 (the resistor in the first integrator) and R2 (the resistor in the second integrator) are varied around their ideal value.The red lines are the R1 root-locus and the blue lines are the R2 root-locus. Let’s zoom in on the positive pole.You can see that R2 mostly affects the frequency of the filter, while R1 mostly affects the damping or Q of the filter.Zooming in on the R1 root-locus, we can see that it also has a small effect on frequency of the filter, but in practice it should be negligible.So, what have I learned? To tune the second-order bandpass state variable filter, one should first tune R2 to the desired center frequency of the filter. Then, one should tune R1 to set the 3 dB bandwidth for the desired Q.Is my analysis correct? Any other tips on tuning state variable filters?

author: Etesla
author_rank: Regular Contributor
timestamp: April 17, 2020, 07:58:12 pm
content: It might not be a bad idea to throw the ideal version of your circuit into a spice simulator like LTspice and run an AC analysis on it. From there, you can easily adjust resistor values and see what real impact they have on the filters frequency response. This would let you know with certainty and pretty much no math what changing each of your resistor values up and down actually impacts.
Tweeting earthquake alarm - Page 1
Forum section: electronics / projects

author: Trigger
author_rank: Regular Contributor
timestamp: July 19, 2011, 01:36:35 pm
content: I saw this on Gizmodo this morning.http://gizmodo.com/5822319/a-chilean-teen-tweets-about-earthquakes-better-than-his-whole-governmentI love how he took what was already there and hacked it to do what was needed. A Government is slow to do anything, and most likely wasteful as well. I know the US Government would probably commission studies costing millions, have review boards for the studies, a review board for the review board, system concept meetings.... you get the point. This is a perfect example of what one Maker, one hacker, can do.

author: Simon
author_rank: Unknown
timestamp: July 19, 2011, 09:32:57 pm
content: typicalJust like the British government, they manage to pay £20 for a light bulb worth £0.20, I hate to think what would happen if they tried to setup a project like that, they'd start by spending millions just by default
TWI - why no stop sometimes - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: April 13, 2018, 11:26:36 pm
content: I've got a couple of AVR's using their TWI interface to talk to each other.ISSUE # 1 - In TWI1.png below, it has a stop/start, but in TWI2.png below, I did not get the stop? It is the same code run again and again.Code:case TWI_MTX_ADR_ACK: //0x18case TWI_MTX_DATA_ACK: //0x28//do we have more to send?if (TWIPos<PROTOCOL_SIZE){//yes, transmit byteTWDR=RxBuffer[TWIPos++];TWCR=_BV(TWEN) | _BV(TWIE) | _BV(TWINT);}else{//send stopTWCR=_BV(TWEN) | _BV(TWINT) | _BV(TWSTO);TWIState=TWISTATE_SENT;}break;ISSUE # 2 - Also in TWI1.png I put a square around a glitch that shows up in many of the bytes sent to the slave. I don't think it affects anything, but is this when one device is turning off and allowing the other to ack/nak it? I see this tiny little glitch on many of the tx bytes. Actually it is on the RX bytes too. Happens during the fall of the clock though and I only think it is sampled on the rise.
Twin tub isolation on P substrate - Page 1
Forum section: electronics / projects

author: blueskull
author_rank: Unknown
timestamp: August 14, 2015, 01:44:58 pm
content: Hi all,1. Can the bulk pin of a NMOS in a P well be connected to its source pin in a twin tub process? If I did that, won't the P substrate be shorted to the source of the NMOS?If I recalled correctly, P well is ohmic connected to P substrate, so the bulk of a NMOS in a P well should be at zero potential all the time, otherwise there will be huge current flowing through it.I saw this in the book "Micro CMOS Design" published by CRC, written by Bang-Sup Song, chapter 2.2. Also, as I read through CSMC's 0.5um MS process datasheets, I found that they say I can construct a diode using N+ and P well. Won't the anode be shorted to the P substrate?I'm a new comer to IC design, so please don't hesitate correcting me.Thanks,Bo

author: Chris Jones
author_rank: Regular Contributor
timestamp: August 15, 2015, 12:56:20 pm
content: I don't know about the process you are using, but I have worked on a process which had P-wells inside N-wells, and the inner p-wells were separated from the substrate by a buried N-layer. That enables, for example, nmos source followers that don't suffer reduced gain from the body effect, because you can tie the backgate to the source if you want. It is a while since I did any chip design so I am forgetting the details now.If your process documentation shows a cross-section through a nmos inside a p-well inside a n-well then that should explain the situation. If you can't find such a diagram, maybe you can ask for one. I think it would be a really worthwhile thing to have.Chris
Twin tube amp from 2 single ended ones? - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: October 22, 2019, 11:33:15 pm
content: so I have 2 identical single-ended EL84 output transformers. and I was thinking would it be possible to wire them in series and use them in a double-ended circuit?
Two-Bit Relay Counter - Page 1
Forum section: electronics / projects

author: German_EE
author_rank: Super Contributor
timestamp: October 25, 2015, 01:59:10 pm
content: Strange things can happen when you are surfing around on the internet. I was looking for a design of relay flip flop and I came across this circuit:http://www.emil.matei.ro/img/onof2a.pngNot only can this circuit divide by two using only two relays but, if you look at the state diagram on the right, it's a two-bit binary counter using only two relays. OK, the count is in the wrong order, but it can still be used by swapping the lines around after decoding.

author: amyk
author_rank: Super Contributor
timestamp: October 25, 2015, 02:29:08 pm
content: PB1 pressed.d1 coil energised.d1.1 and d1.2 closes.d2 coil energised.d2.2 and d2.1 switchd1 coil deenergised (same potential on both ends)d1.1 and d1.2 opens.Looks more like a pulse generator to me.

author: eetech00
author_rank: Regular Contributor
timestamp: October 25, 2015, 06:10:08 pm
content: HiHere is a relay Flip Flop circuit.It uses a center off switch.
Two DC-DC Converters same frequency? - Page 1
Forum section: electronics / projects

author: mrburnzie
author_rank: Regular Contributor
timestamp: August 16, 2022, 12:51:36 pm
content: Hi!I have a design where I have two DC-DC converters. One is 5V output other is 3.3V.They are both adjustable switching frequency.I haven't found much documentation on the fact that when two converters are close to each other, should the switching frequency be the same or be different (and by how much)? What is better for EMI?

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 16, 2022, 01:30:29 pm
content: Ideally, they should be the same frequency but 180 degrees out of phase.

author: Zero999
author_rank: Super Contributor
timestamp: August 16, 2022, 01:48:48 pm
content: Quote from: NiHaoMike on August 16, 2022, 01:30:29 pmWhich won't happen unless they're synchronized. If they're very close in frequency they'll probably phase lock and both run at exactly the same frequency.

author: mrburnzie
author_rank: Regular Contributor
timestamp: August 16, 2022, 02:35:49 pm
content: Okay, but what will happen with the functionality and the EMI?

author: m98
author_rank: Frequent Contributor
timestamp: August 16, 2022, 02:47:42 pm
content: Spread the energy out a bit to reduce your peak envelope, run them at different frequencies, just don't have one be a harmonic of the other. Operating two converters in-phase at the same frequency would be pretty much the EMI worst-case, but in any case, some shielding and filtering will probably be required.

author: David Hess
author_rank: Super Contributor
timestamp: August 17, 2022, 02:49:10 am
content: Quote from: Zero999 on August 16, 2022, 01:48:48 pmI have never seen them injection lock unless there was a circuit addition to force it.Quote from: m98 on August 16, 2022, 02:47:42 pmSome sensitive DC circuits will be upset if the converters are close in frequency because of the low frequency mixing product, so it is better to be injection locked or operating on distant frequencies.
Two identical barrel jacks.  One rated for 2.5A the other for 5A.  Why? - Page 1
Forum section: electronics / projects

author: Starlord
author_rank: Frequent Contributor
timestamp: March 07, 2015, 12:48:46 am
content: http://www.cui.com/product/resource/pj-102a.pdfhttp://www.cui.com/product/resource/pj-102ah.pdfThe only apparent physical difference between these two jacks is that the solder terminals on one are plated in tin, and the other in silver. The specified resistances are the same, the plating of the barrel itself is the same. Yet the tin one is rated for 16V 2.5A, and the silver one is rated for 25V 5A. Why? Does tin break down at high currents / voltages?

author: Lightages
author_rank: Unknown
timestamp: March 07, 2015, 01:09:15 am
content: I would hazard to guess they are identical except for the plating. One was probably designed and manufactured to a specification of one customer or the engineering department and the other relabeled to meet the specs of another client. This happens all the time with components.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 07, 2015, 02:12:12 am
content: Good question... ask them.Connector current rating is a pretty dubious thing, anyway. Contact resistance is all over the damn place, so estimating temp rise at some current capacity is almost absurd.0.1" pitch headers, for example, aren't normally rated beyond 2-3A, but you can find ones rated for 4-6A. And those ratings, in turn, are usually "per pin", meaning, not just for one pin at a time, but just one pin, exclusive. They don't always/usually mention what total current rating would be for all pins wired. Let alone if you wire pins in parallel, and hope that the current shares!It is curious that it's such a large difference (a factor of 2!) for absolutely no identifiable reason. I notice they don't specify the terminal thickness in either case. Which could maybe be different, but yeah... they probably are the same damn thing, plating only.I suppose the moral of the story is:See a factor of two advantage? Take two backwards and call that a safe maximum! (I.e., 2.5 or 5A? Hell no, we're calling it 1.25A, tops!)Tim

author: Psi
author_rank: Super Contributor
timestamp: March 07, 2015, 02:37:29 am
content: one is tin plated and the other is silver plated.

author: Rufus
author_rank: Super Contributor
timestamp: March 07, 2015, 02:43:41 am
content: Quote from: T3sl4co1l on March 07, 2015, 02:12:12 amLumberg make a panel mount jack 1614 09 rated at 0.5A and <30m ohm resistance.CUI make a cable mount jack PR-002A which looks identical apart from different style solder tags and a PVC strain relief instead of a nut. The PR-002A is rated at 4.0A and <50m ohm resistance.Max current and worst case resistances give power dissipation different by a factor of 107!From this one can deduce that current ratings for this type of connector are made up crap with Lumberg at one end of the spectrum of crap and CUI at the other.
Two-MOSFET soft-latching startup switch - Page 1
Forum section: electronics / projects

author: asgard
author_rank: Regular Contributor
timestamp: December 01, 2012, 08:34:33 pm
content: I hope that something inordinately stupid is going on with my little grey cells.I have here, first, an LTSPICE simulation of a two-MOSFET soft-latching circuit, with plots of the trigger and output voltages.C1 also works in the simulation at 1uF perfectly well. The second picture here is the EAGLE equivalent circuit using an actual dual IRF7343 MOSFET device. The problem I am having with this is that when the actual hardware is assembled the output voltage seems to be stuck in the "on" level, with no change other than a brief spike in the gate of M1. Is this a case where LTSPICE has led me astray, and if so, how much can I rely on SPICE models in the future to correctly characterize specific real-world circuitry?J.R. Stoner

author: Psi
author_rank: Super Contributor
timestamp: December 01, 2012, 11:08:55 pm
content: I notice you have the led+resistor connected differently in LTspice vs the diagram.If you're using that to tell you the state you maybe getting confused.In LTSpice you have led+res powered from drain D2 (the output) but in the circuit diagram you have it off drain D1.So the LED will always be on as current will flow from VCC through the 10k then the 1K then the led to gnd.

author: asgard
author_rank: Regular Contributor
timestamp: December 02, 2012, 04:19:13 am
content: My test board actually has the LED and resistor connected to D1, which is (I hope) supposed to be what the SPICE model relates.I am _really_ hoping the SPICE model is not telling me a fib, as the LED sinking from D1 only shows brief spikes (about 125msec) no matter how long S1 is pressed.Here is the picture of the test setup in actual hardware.
two mosfets in serie to make AND function - Page 1
Forum section: electronics / projects

author: diegopm
author_rank: Newbie
timestamp: December 17, 2020, 10:01:36 pm
content: Hi,I need to activate a device when 2 signals go high, the enable is negated, so I am thinking to use 2 mosfet in series like picture.Could be suitable the use of these transistor in this way?I think there is no problem, there is no violation in the values of the transistor.cir2mosfet.JPG(44.64 kB. 754x580 - viewed 161 times.)Thanks BR.

author: mck1117
author_rank: Contributor
timestamp: December 18, 2020, 12:25:30 am
content: Well done, you've inventedNMOS Logic!Except that's a NAND gate, not an AND gate. You could add another single resistor + FET to invert the output and make it in to an AND.