hybridfree/eevblog-posts huggingface dataset:
FE-5680A Rubidium oscillator - enable option 2? - Page 1
Forum section: electronics / projects

author: JJalling
author_rank: Unknown
timestamp: November 18, 2017, 12:52:31 pm
content: Hi all,I have an old FE-5680A which, I think, doesn't have option 2 enabled (serial configuration).When I send the command 0x2D 0x04 0x00 0x29 to read out the tuning register, it never replies. I have measured that the serial signal actually gets to the RX-pin on the DS80C323 processor, but no signal is returned on the TX pin.Is there any way to enable option 2?Thanks, Jonas

author: JJalling
author_rank: Unknown
timestamp: November 18, 2017, 05:51:20 pm
content: ... Actually I don't think this is related to option 2 - the calibration should, as far as I understand, be possible on all devices - can someone confirm this?BR Jonas

author: richnormand
author_rank: Unknown
timestamp: November 18, 2017, 06:05:49 pm
content: Have a look at these links:http://www.leapsecond.com/time-nuts.htmhttp://www.ko4bb.com/doku2015/doku.php?id=precision_timing:fe5680a_faqhttp://www.ko4bb.com/doku2015/doku.phphttps://hackaday.io/project/11514-hacking-a-fe-5680b-rubidium-reference-clockFirst one is time nuts and search FE-5680. There are lots of references and hacks for these units.Second and third is KO4BB site and the wiki. They also have a copy of the several x-rays I did when fixing my FE-5680A(contact me should you need a specific x-ray of a region of interest. Files are huge)Fourth is hacking to get other signals on the board.Best of luck with it.

author: JJalling
author_rank: Unknown
timestamp: November 19, 2017, 07:02:51 am
content: Hey Rich,Thanks for the info! If I have any luck fixing it, I'll report back here.BR Jonas

author: AlfBaz
author_rank: Super Contributor
timestamp: November 19, 2017, 12:01:57 pm
content: I don't suppose either of you happened to have downloaded the contents of the xilinx cpld in jedec format (*.jed file)?I have a 5680B which appears identical to the A version and believe that flashing the A version of the jed file will keep the 10MHz signal on instead of turning it off after a few seconds, which is what the B version does.
FE5680A LED Buffering - Page 1
Forum section: electronics / projects

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: August 10, 2019, 05:34:57 pm
content: Hello everyone!So i made a circuit based on this schematic:https://i.postimg.cc/cLJZxwtF/LED-Buffering.jpgThe circuit is powered off course by using 7805 regulator. The circuit works but only for LOCK indication, 1PPS indication LED is always ON. I have checked on breadboard connections and everything is OK.What am i doing it wrong?Thank you!

author: DaJMasta
author_rank: Super Contributor
timestamp: August 11, 2019, 04:27:20 am
content: Your PPS input signal is all wonky. You have nearly zero volts on it at all times thanks to the resistor divider, and your diode on the input prevents current from coming in to change that. I think you're trying to use the diode and resistors to invert the input signal... but there are a lot of extraneous parts. I don't the polarity of the PPS signal is usually significant, either, but you can reverse it by reversing the LED direction and putting it to ground if desired.I'd remove:D2, R12, C6 (and R5, really)thenD3 and R14then probably change R13 to a lower value - only really necessary to limit power output/current driven into the far side, so enough to protect the chip should be plenty. Maybe putting that 47 Ohm resistor in place of R13 is about right, but it depends on your potential load.As a little extra aside, R8 does basically nothing (a current limiting resistor or voltage divider should be on the previous stage if needed, as it is right now it doesn't really protect anything), R7 (like R5) is only useful if your circuit can expect to be run without the inputs attached, and C4 doesn't really serve a purpose. Maybe C6 or C4 should be used to bypass the supply of the IC instead.
Feasibility about idea - Signal following machine - Page 1
Forum section: electronics / projects

author: gonzalito
author_rank: Contributor
timestamp: September 17, 2025, 11:58:37 am
content: Good day everyone. I hope everything is going well.there is an idea I'd like to take some advice for. I need to make a robot follow an underground cable (buried about 2cm).The idea is to inject a signal into this cable. Lets say through a 555 or some sort of pulse or signal generator, and make a linear arrangement of "pickups" or something similar, lets say about 30 of them on the robot so that the machine can "read" the signal strength of the cable on a defined set of pickups and that way know what position its travelling and orient itself.Have you ever met anything like it? do you know where can I get some ideas to start building one? Or any advices on what to take into account?To make it clearer... Top view, black rectangles are wheels of the machine, the orange line is the cable that carries a signal, and the black dots are the individual pickups that make the array.best regards,Gonzalo.

author: Berni
author_rank: Super Contributor
timestamp: September 17, 2025, 12:44:25 pm
content: Yep this is how the non smart robotic lawnmowers sense the boundary wire.As you said you just have to pulse the current in the wire at a certain frequency, then you can use a tight bandpass filter on the sensing coils to pick out just that 1 frequency (since you have to ignore the 50/60 Hz mains hum that is all around). This means some analog opamp circuitry to do the amplification, filtering and demodulation. The resulting DC signal can then be fed into a microcontrollers ADC.You don't actually need that many coils. You can use just 2 coils and compare the amplitude between them, when they are equal that means the wire is in the middle. Also you likely want to tilt your sensing coils sideways since that's the direction the magnetic field lines are going to be going right above the wire.

author: gonzalito
author_rank: Contributor
timestamp: September 17, 2025, 07:07:50 pm
content: Correct the main thing is that the machine is big and the sensing zone underneath the pickups is large, about 80cm wide.But we can manage to use just enough pickups and interpolate their signal strength to maintain a certain position around the cable.
Feature Suggestions for Open-Source Doorbell Project - Page 1
Forum section: electronics / projects

author: sydundar
author_rank: Contributor
timestamp: May 03, 2025, 08:01:12 pm
content: for more details:https://www.crowdsupply.com/fusionxvision/fusion-chime-visionHello everyone,I'm currently developing an open-source smart doorbell system called Fusion Chime Vision, and I'm seeking your insights on potential hardware enhancements and Home Assistant integration features.🔧 Hardware Improvements:Before initiating the crowdfunding phase, I'm considering some hardware upgrades:Camera Upgrade: Transitioning from the OV2640 to the OV5640 sensor to enhance image quality.NFC/RFID Integration: Several users have expressed interest in incorporating an NFC/RFID reader for access control. I'm curious about its practicality and demand, especially in the U.S. market. Would this feature be beneficial in your opinion?Are there other hardware functionalities you believe would be valuable?🧠 Software Suggestions:I'm exploring potential features for Home Assistant integration. For instance:Sending notifications when the doorbell is pressed.Reporting PIR sensor trigger events.What other functionalities would be beneficial?

author: voltsandjolts
author_rank: Unknown
timestamp: May 03, 2025, 08:05:30 pm
content: No need for another thread, please use the first thread you created. Thanks.https://www.eevblog.com/forum/crowd-funded-projects/esp32-based-opensource-smart-doorbell-system

author: Kleinstein
author_rank: Super Contributor
timestamp: May 03, 2025, 08:09:54 pm
content: If one has some kind of phone system in the house it is really nice to connect to the normal (especially wireless) phones. This is really handy when in the garden.Including the wireless phone part could still be tricky (they tend to be limited to one base station) and RF sending parts need quite some paperwork / testing.
features for dekatran ratio box - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: March 09, 2025, 03:18:00 am
content: I have a dekatran transformer that I thought might be useful in the lab from a while back.It has solder lugs on it, and I wanted to put it in a enclosure with connectors, so its lab equipment instead of cylinder with wires hanging out of it. What connectors or features do you think would be good?One method I thought of is to have the connectors on the back, so the wiring is as short as possible, but it makes it annoying to use. The other idea is to use connectors on front, so its like test equipment.And how about connectors. I thought 3x banana plug (binding post) is good, but then maybe I thought to use 3x BNC connectors. Or maybe 3x isolated BNC connectors with enclosure-link toggle switchesAnd I also thought to make the box of out of magnetic material (steel).I thought maybe it could be useful for audio work or lock in amplifier stuff (I do have a commercial LI-Amp, but its still a interest of mine).

author: coppercone2
author_rank: Super Contributor
timestamp: March 11, 2025, 05:50:00 am
content: another idea is to put coaxial cables inside of the box to have connectors on the front panel, and shield them at a star ground on the pin of the pin that is connected to the chassis of the transformer (cylinder)?
Feedback follower circuit - Page 1
Forum section: electronics / projects

author: Burning Circuits
author_rank: Contributor
timestamp: May 08, 2020, 06:43:38 pm
content: Hi,I have a question regarding the attached circuit (a power supply).The LT8612 is the switching pre-regulator of the two linear LT3081 regulators.I have understood the purpose of Q3: it's a feedback follower, that keeps the output of the pre-regulator 1,7 V higher than the output of the LT3081 (VOUT).The voltage at the FB pin of the LT8612 is 0,97VI don't understand the mathematical relation between the resistors value and the 1,7 V value.Someone can help me?

author: unitedatoms
author_rank: Frequent Contributor
timestamp: May 08, 2020, 07:42:55 pm
content: With reference voltage of feedback known from datasheet 0.97V and resistor 4.99k the collector current is 0.19 mA.The high beta transistor makes base current negligible. So then dividing pair of 100k resistors is loaded to very low current of base. Divider is then equal: Makes transistor to open up to necessary 190 uA at doubled opening voltage.So1.7v=2*(voltage pn + o.ooo19*1000 ohm). Where voltage pn is 0.65v for slightly opened silicon transistor.

author: mawyatt
author_rank: Super Contributor
timestamp: May 08, 2020, 08:13:21 pm
content: A quick circuit analysis shows thatVx = Vo + 2(Vfb*R1/R2 + Vbe)Where Vx is the voltage in question, Vo is the output, Vfb is the feedback voltage of Lt8612 (0.97V), R1 =1K, R2 =4.99K, and Vbe is base emitter voltage of Q3 PNP.Hope this helps.Best,Mike
Feedback in "isolated" DC-DC - Page 1
Forum section: electronics / projects

author: nihial
author_rank: Regular Contributor
timestamp: January 24, 2025, 03:55:33 pm
content: Hi,I have a 28-180DCDC power supply whose controller got obsolete and I want to replace it.I found an alternative (NCP1397A) but the feedback isn't working the same way as the previous chip.The previous chip had the following logic : the lower the voltage the higher the switching frequency and pulse skip at some point.The new one has the opposite logic.Even if the DCDC uses a isolated topolgy, the output isn't isolated so the feedback doesn't need to be isolated.The feedback that was used in the previous design is an integrator you can see below, the reason of the initial designer was to avoid at all cost a optocoupler because of space constraints.Now since the logic has been inverted I can't use that feedback circuit anymore. I'm looking for an elegant way with the minimum real estate used but I can't find anything that I find decent.I have also absolutely no idea how the feedback in the isolated case are designed in the case I have no choice but to squeeze an optocoupler.Any idea/help would be appreciatedBest regards
Feedback loop problem in LNK3202 based Buck converter? - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: June 16, 2018, 07:35:31 am
content: Hello,The second diagram down on page 7 of the Linkswitch-TN2 datasheet shows an optocoupler being used to regulate the buck converter.If the opto delivers more than 49uA into the FB pin of the LNK3X02, then the LNK3X02 stops switching.However, the connection of the opto_diode in series with the zener diode looks very precarious. Do you believe it would be that bit more secure if 100R was placed in series with the zener? –Just to limit the current in the zener from potentially running away.LNKswitch –TN2https://ac-dc.power.com/products/linkswitch-family/linkswitch-tn2/
Feedback needed:  cell phone pogo pin charger - Page 1
Forum section: electronics / projects

author: matt6ft9
author_rank: Contributor
timestamp: October 05, 2015, 02:18:26 am
content: This is a half baked, project idea. I would like some feedback on if it is a good/bad idea, pitfalls, any thoughts:There seems to be some news lately about charging cell phones/watches by an inductive pad. (This is how the apple watch charges and some electric toothbrushes) The main idea behind this is convince. It is much easier to put a phone on a pad than to grab a USB cable charger, orient the plug and then insert the plug. One problem with inductive charging is it's lossy. When you multiple the wireless charging losses by a billion cell phones, that's a bunch of wasted power.So, why not put two, round, 1mm in diameter by 0.5mm tall pogo pins on the backside of a cell phone? Pogo pins similar to: (attachment: pogo.png)The charging mat would be a 15cmx15cm FR-4 PCB with a grid of 2mm square SMT power pads. (0.4mm spacing between the pads?) The pogo pins would contact the power pads on the FR-4 material. Each pogo pin would contact between one and four charging pads. Software in the charging mat would have to find the pogo pins and supply power. (bridge rectifier would be needed in the cell phone?) The software would also have to detect when the cell phone was removed.There are a couple of downsides to the pogo pin idea:-The pogo pins could get gunked up and loose their springiness.-The pogo pins would stick out of the back of the phone, it might annoy the user-No metal back-shells on the phones, only plastic-No pogo pin charging while moving in a vehicleThe one big upside is pogo pin charging seems like it would be more power efficient than wireless charging.Matt
Feedback needed on Universal Hi-Link HLK Board design  - Page 1
Forum section: electronics / projects

author: ljswart
author_rank: Newbie
timestamp: March 13, 2025, 06:45:19 am
content: Hi everyone.I am busy developing a universal Hi-Link HLK board, and am looking for some feedback/improvements that can be made.Design is on EasyEda Pro, with manufacturing through JLCPCB. 1oz copper pour, FR4.The board has footprints for 5MXX, 10MXX, 20MXX, PMXX. Board and parts should be specced appropriately to accommodate these modules.Board has 240VAC input.Thank you in advance!

author: jwet
author_rank: Frequent Contributor
timestamp: March 14, 2025, 03:12:59 pm
content: A few comments- it looks pretty good overall. All comments are meant to be constructive.It might make for a better layout if you turned the fuse and CM choke 90 degrees. This would put the fuse in the top left with MOV and TVS to the right of it. CM choke would be below and would run straight. The isolation tracks are good but the one on the input looks like it will make the board flimsy. If you do the above, you can fix this.The stitching between the two sides of the boards is not required- but it can't can't hurt. It reduces conductor area on the input.After the supply, you have that enormous V+ trace and a ground plane for V-, If you look at where the current on the neg side can actually go, its kind of skimpy, it goes around the edges and through corners- the overall area isn't probably isn't bad. Why not just put two fat traces. Is the plane to dissipate heat?I would leave plenty of room for output caps and maybe even some room for series L's of various sizes since its universal.Mounting holes?- edit I see them, check clearances on output side. I usually allow .375" (10 mm) diameter keepout around MTG

author: coromonadalix
author_rank: Super Contributor
timestamp: March 14, 2025, 03:47:29 pm
content: same herei would have rotated parts to avoid looping around an ac line for the otherother preivous comments
Feedback on 4 channel current shunt pcb - Page 1
Forum section: electronics / projects

author: WaldPinkler
author_rank: Contributor
timestamp: September 28, 2021, 05:24:38 am
content: I'm new to this. I'd love some feedback. It's a 4 channel shunt with a PAC1934 with barrier terminals. I'm hoping up to 15A.I don't know what I don't know so I hope a dual layer 1oz board is enough. It's double sided around the pads with arrays of vias going to shunt resistors. 9.5mm pitch on the terminals to get an idea of size.It got very tight with the PAC chip trying to keep it in that small space.My concerns:Is the via pad set up ok? I have no idea.How about running the sense traces down through the middle?Is it okay to be so tight with the main chip?I still have some spit and polish, silk screen, etc. Also to figure out the difference between the Vcc and Vio. I didn't decide on shunt values yet either but selected that wide shunt resistor that I can test different values.
Feedback on HLK-5M05 AC to DC circuit  - Page 1
Forum section: electronics / projects

author: ilium007
author_rank: Frequent Contributor
timestamp: October 19, 2020, 08:10:30 am
content: I am looking at using the 5V 1A HLK-5M05 AC-DC converter on an ESP32 based home automation project PCB. Schematic and HLK-5M05 datasheet attached.I need some advice on sizing the MOV or if I should even be using an MOV vs a TVS diode. I am reading things about MOV's catching fire in peoples walls and roofs and TVS diodes being a more modern approach to surge protection.In Australia we have 240VAC 50Hz (our nominal voltage here is around 253VAC shown on a digital meter).Can anyone help with some advice on voltage suppression components and best practice?

author: ilium007
author_rank: Frequent Contributor
timestamp: October 20, 2020, 06:37:59 am
content: All of the other circuit examples using the HLK-5M05 are using MOV's with a series slow blow fuse, I'll just use the same. Are there 'go to' MOV's that people use for 240VAC RMS?(240VAC * 0.707) * 20% = 407VACSo should I just look for a 410VAC MOV with decent surge current capacity?Is the 410VAC the clamping voltage or the max continuous voltage I see on datasheets?
Feedback on Motor Controller - Page 1
Forum section: electronics / projects

author: diablodude64
author_rank: Contributor
timestamp: February 12, 2025, 10:17:36 pm
content: Hello,I have been working on a motor controller for a power wheels Jeep and I think this is just about ready but I am by no means a professional in this area. I would really appreciate some feedback on whether as it currently sits, this circuit is functional and if there were any thing that I should change before doing the PCB layout. I will add TVS diodes to the pedal assemblies at the hall effect sensors so they are not shown on this diagram.The teensy will get 12v all the time but it will utilize it's sleep functionality to minimize voltage draw as the Jeep will be charging when it's not in use anyways. The key will be the signal to wake up and if all is well in the world, the contactor will be sent a signal to close for the 24v side of the circuit. The CAN transceiver is for a future dash screen.Thanks!
Feedback on Passthrough Charging Circuit - Page 1
Forum section: electronics / projects

author: DiscoD2682
author_rank: Newbie
timestamp: June 16, 2024, 02:19:16 am
content: I'm working on a robotic car project that I want to run off of lithium batteries that charge off of USB-C. I'm a programmer that doesn't do electronics often and wanted feedback on the power circuit for it. I'll need to draw up to 5-6A at 5V at peak. I also need the car to still be powered when plugged in as it has other capabilities beyond movement (and will have a software mechanism to disable the drive motors so it doesn't drive off while charging). While plugged in, I also want the battery to charge even if the car is on.Could anyone who has the time take a look at the attached circuit diagram to power the project off of USB-C when available and fallback to an internal battery pack and inspect for safety / other issues?If there's a simpler solution that still provides the necessary amperage, please let me know.The batteries are Samsung 50S 21700 cells (5000 mAh, 25A max output)Battery datasheet:https://cdn.shopify.com/s/files/1/0481/9678/0183/files/INR21700-50S__Cell_Specification_V0.2_200911.pdf?v=1654906866(Because I need to draw more than most cheap buck converters like the LM2596 can provide, I may end up using multiple buck converters to power separate motor controllers).Also, I'm open to suggestions as to alternatives for the TP5100, but for now am going with it as I need to get the parts shipped quickly.Thanks

author: ledtester
author_rank: Super Contributor
timestamp: June 16, 2024, 04:18:41 am
content: You should also be able to get away with removing the diode on the right and adding a connection from the unused relay contact to the charging + terminal if your system can tolerate a slight interruption in power when the relay switches over.

author: DiscoD2682
author_rank: Newbie
timestamp: June 16, 2024, 05:35:20 am
content: Quote from: ledtester on June 16, 2024, 04:18:41 amThanks so much!! I'd been trying to get rid of that diode with no success, but that makes total sense. If I added a suitably large capacitor just before the buck converter, could that alleviate the power interruption problem?

author: Peabody
author_rank: Super Contributor
timestamp: June 16, 2024, 03:02:39 pm
content: Would you consider doing it with mosfets? That would eliminate the switching glitch, and might be smaller and cheaper, and longer lasting, than the relay.Edit: It seems the circuit below might work. They are P-channel mosfets.

author: Peabody
author_rank: Super Contributor
timestamp: June 18, 2024, 02:25:22 pm
content: Perhaps the OP has answered his questions, but could someone confirm whether my circuit in the post above would work in place of the relay? It requires that USB voltage be at or above battery voltage.
Feedback on Power Path & Charging Design for 2S9P Samsung 50E Battery Pack - Page 1
Forum section: electronics / projects

author: jakethesnake
author_rank: Newbie
timestamp: May 06, 2025, 12:18:31 am
content: Hello all,This is my first post on eevblog!I'm designing a power path system with the LTC3891 for DC-DC conversion and LTC4000 for power path control (schematic attached). The system will power an ESP32, 120 watts of WS2812 Eco pixels (yes, it's a lot), and a dedicated ESP32 WiFi antenna. It will be powered by a 2S9P Samsung INR21700-50E battery pack, which I plan to charge at 0.33C and discharge at 1C. The LTC4000 is supposed to switch to battery power when the +12V external input voltage drops below 6V.Key Notes:* Active load balancing will be added later and will shut off battery discharging when the battery voltage drops below 6V (please tell me if this value doesn't seem right!).* A buck converter will be integrated in future stages to get a +5v stable output to the system.Questions:1. Component Power Handling: Are the LTC3891, LTC4000, and MOSFETs properly rated for the expected power draw (battery and 12V input)? Any thermal concerns or improvements I should consider?2. Seamless Power Transition: Should the switchover from external power to battery be seamless enough for the ESP32, WS2812 pixels, and WiFi antenna? What changes might improve the transition?3. Resistive Divider Accuracy: Will my resistive dividers maintain the battery voltage between 6V and 8.4V during charging as intended?4. Battery Charging and Discharge: Will this system charge the 2S9P Samsung 50E at 0.33C and support 1C discharge without over-stressing the battery or components?5. Thermal Management: Is there enough thermal headroom for components like the LTC3891, LTC4000, and MOSFETs? Any thermal design improvements needed? I haven't started the PCB design yet, waiting on schematic validation here first!6. Capacitor Sizing and Filtering: Are the capacitors in the power path correctly sized for the current draw? Should I add bulk capacitance or ceramic capacitors to improve transient response?7. Continuous Current Handling: With a +5v 45A load (assuming I've added the system load buck converter), will this design handle continuous current without overloading the battery or components? Are the MOSFET ratings adequate?8. Efficiency of Switchover: Is the LTC4000's switching mechanism efficient enough to minimize voltage drop during the transition to battery power? Should I add protection or safeguards?9. Estimating Output Voltage: How do I estimate the output voltage, especially during brief dips in the switchover? How should I account for voltage loss across the components—from the battery to the system output?10. Simultaneous Load and Charging: Will the components I have selected be able to handle powering the system, whilealsocharging the battery pack at 0.33C?Any feedback would be greatly appreciated. Thanks in advance!
Feedback on routing JTAG signals - Page 1
Forum section: electronics / projects

author: fitzgerald
author_rank: Contributor
timestamp: November 30, 2016, 09:07:56 pm
content: I'm having a bit of an issue with nicely routing the JTAG signals to a Cortex 10-pin debug header. Or maybe I'm just looking at it for too long.See attached figure. RA1 is a 4x resistor array with pull-ups. J5 is the debug header.Any hints or tips on how I could improve this further?

author: bson
author_rank: Unknown
timestamp: December 01, 2016, 02:30:36 am
content: I went tag-connect for all my boards. Easy enough to fit right in the middle someplace with minimal fuss.http://www.tag-connect.com/Here's a couple of TI MSP430 based boards with a TC connector (used for the TI-FET), as you can see it's really small and very easy to find a convenient spot for. Doesn't even require a connector, just a footprint.

author: julianhigginson
author_rank: Frequent Contributor
timestamp: December 01, 2016, 04:07:05 am
content: Quote from: fitzgerald on November 30, 2016, 09:07:56 pmYou could really do with a polarisation marker on your programming connector footprint. Make sure people get it the right way round every time. Even if you're using a polarised connector, it's another hint to the assembly people what way round to place it.TCK net would be better without the acute angle in the copper where the net splits form the connector. It wont likely cause manufacturing failure, but in general it's just something best avoided.Also, TCK net doesn't need routing around the back of the pins and coming out the corner of the chip. I'd just route it straight out with the others, then bring it down on the underide of the board, left of the existing TMS track. then pop up a via to a track going right between the pullup and the connector pad.Or route something down the centre of the connector if you want to save a pair of vias and a track on the underside.As for tag connect - I worked on a project with tag connect stuff earlier this year.. not sure I like it or not. It definitely does save space, and worth using where there's no option for a full connector footprint and no chance of a basic jig for programming being made. Just, if you want to use it, then that's more finicky small things to look after and make sure people have plenty of spares.

author: fitzgerald
author_rank: Contributor
timestamp: December 01, 2016, 05:01:56 pm
content: Thank you very much bson and julianhigginson. Please see attached figure for my implementation - still need to put the pull-ups back in though.The 'aha' moment for me was that the Tag Connect solution allows me to put the footprint on the back side of the PCB without an additional reflow run required. Current solution has the same amount of via's, with cleaner routing and more space available on the component side. Thanks
Feedback requested for Quiz on electronics and embedded systems - Page 1
Forum section: electronics / projects

author: kind_guy
author_rank: Newbie
timestamp: November 26, 2014, 04:47:39 am
content: Last few days, I worked on few quiz-lets on electronics and embedded systems for fun. Here is the link:electronicshttp://fpgasystem.blogspot.com/p/quiz.html:I will appreciate if experts can try these quizeshereand provide me your constructive comments.Please note this is still work in progress and I am planning to post more quiz-lets.Also, it would be real fun if you can share how you scored on those.I will greatly appreciate.

author: miguelvp
author_rank: Super Contributor
timestamp: November 26, 2014, 05:40:13 am
content: Myself I think it's all over the place, do I need to know zigbee for microcontollers?Also why use the 8051?No progress so you don't know how many questions are left.Use of abreviations on questions, for example SFR when on a previous question you mention Special Function Register all spelled out.SCL in I2C being bidirectional its a strech.In one quiz I got the answer wrong and it told me the valid answer was C but the valid range for the answer was 1-4

author: kind_guy
author_rank: Newbie
timestamp: November 26, 2014, 07:07:57 pm
content: Thanks miguelvp, very helpful feedback.Appreciated.
Feedback: Simple RF Analog Switch PCB with 50 Ohm Traces - Page 1
Forum section: electronics / projects

author: Chendy
author_rank: Contributor
timestamp: November 27, 2024, 03:03:24 pm
content: I'm trying to design a simple RF Antenna Switcher, I'm new to RF design.I want a 50 Ohm controlled impedance trace between my Antenna connector (IPEX 20579-001E) and an RF Switch (BGS12P2L6)I've been speaking to a PCB manufacturer, to determine the exact trace width to achieve 50 Ohms, given their PCB specifications.I didn't want the trace width to be too thin, as manufacturing tolerances would impact the target 50-ohm impedance too much:- Bad: a 0.1mm trace with 0.01mm manufacturing tolerance (10% error)- Better: a 0.5mm trace with 0.01mm manufacturing tolerance (2% error)So my question...The PCB manufacturer mentioned:"Because the impedance line is short and in the pad, it will cause dielectric losses."Is my approach for the highlighted microstrip trace (polygon) correct? Please see the images below- The connector pad is essentially the same width as the desired 50 Ohm trace- The RF Switch pad is much smaller, so I have tapered the polygon as it approaches- I've tried to place the connector and switch as close to as possible- I've read that it's beneficial to remove the trace solder mask, to reduce dielectric lossesI'm aware of coplanar waveguides, but I have read they have higher losses at my frequencies of interest, a 5G antenna, up to 6 Ghz.Any help is appreciated! : )
Female version of Mini-Fit Jr. 5557 - can't find it - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: October 06, 2020, 12:53:36 am
content: Looking for the female version of this connector. One that has a pair of wires coming out of it, not one that solders to a PCB. I want to make a plug-in extension for a cable that is terminated with this connector. I've looked and looked but there are just so many different types I can't figure it out.https://au.element14.com/molex/39-01-2020/connector-housing-rcpt-2pos/dp/151866?st=minifit#

author: langwadt
author_rank: Super Contributor
timestamp: October 06, 2020, 01:38:10 am
content: you are looking for the male part, e.g .https://uk.rs-online.com/web/p/wire-housings-plugs/6795767/

author: Circlotron
author_rank: Super Contributor
timestamp: October 06, 2020, 02:11:10 am
content: Quote from: langwadt on October 06, 2020, 01:38:10 amThanks for that, langwadt. I did see that particular one in my travels but I thought it might not have been the right one because of the unused "wings" on the side. It must suit several different kinds of matching connector.As for male vs female, I was going on the plastic moulding shape rather than the metal connector shape. So it's the metal that defines the gender. I learned something new.

author: Monkeh
author_rank: Super Contributor
timestamp: October 06, 2020, 02:13:33 am
content: The 'unused wings' are panel mounting latches.
Femtosecond Jitter, Ultra Low Phase Noise oscillator. - Page 1
Forum section: electronics / projects

author: jippie
author_rank: Unknown
timestamp: May 06, 2015, 03:10:16 pm
content: Anyone a well-founded opinion abouthttp://www.pulsarclock.com/index.html?Interesting claims pop up when you Google around a bit, like:http://www.diyaudio.com/forums/vendors-bazaar/258789-pulsar-clock-ultra-low-noise-ocxo.htmlApart from the audiophile claims, are the specs really so impressive and/or can such specs actually be met by the devices (both oscillator and voltage regulator) and would it require special design considerations on your circuit board (eg. the amplifier)?

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 06, 2015, 03:38:12 pm
content: Might make a significant difference in the amplifier attached.
Fer-rite core Transformer - Page 1
Forum section: electronics / projects

author: whatty
author_rank: Contributor
timestamp: February 20, 2023, 04:08:28 pm
content: Hi,I am designing a fer-rite core transformer for a power supply its about 12v 2 ampsI got the following dataprimary inductance = 600uhsecondary inductance = 12uhprimary turns = 63secondary turns = 10turns ratio is 6.3primary peak current = 1.25Ausing fer-rite core of EE 25/13/7 which has AL value of 489nh/turns and airgap of 0.1mm so that it doesn't saturate at 1.25ampshow could i verify the Air gap is enough to store the energy for the given transformer

author: tooki
author_rank: Super Contributor
timestamp: February 20, 2023, 04:39:31 pm
content: The word is “ferrite”.

author: whatty
author_rank: Contributor
timestamp: February 20, 2023, 04:44:56 pm
content: Hi,I i type ferrite it shows red line beneath it so i made a - in between fer and rite

author: jonpaul
author_rank: Super Contributor
timestamp: February 20, 2023, 05:02:59 pm
content: learn by researche and readingeasy to adjust the gap, we use fish paper or G10 on un gapped ferrite corej

author: TimFox
author_rank: Super Contributor
timestamp: February 20, 2023, 05:34:00 pm
content: "Fair-Rite" with hyphen is a trademark for a vendor of ferrite products.(No annoying red underline appeared when I typed "ferrite" above.)

author: whatty
author_rank: Contributor
timestamp: February 21, 2023, 04:19:42 am
content: yeah but i need to theoritically verify that the the given air gap is enough for the given design specifications .
ferrite bead for 22gauge wire - Page 1
Forum section: electronics / projects

author: tekman11
author_rank: Contributor
timestamp: October 12, 2014, 02:43:55 pm
content: Hi all,years ago I used ferrite bead that could be slipped over 22 gauged wire. The freq range is 20-100 MHz.I been unable to find a source, any help would be appreciated?thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 13, 2014, 02:13:05 am
content: http://www.mouser.com/ProductDetail/Fair-Rite/2643000301/?qs=%2fha2pyFadujj1iw7Jdg2Jou73VcOfy39LRjyl9BDXZE%3d?No shortage of selection or availability

author: Neilm
author_rank: Super Contributor
timestamp: October 13, 2014, 06:19:13 pm
content: What attenuation were you after? If you look at ferrite specs you should be able to find the impedance curves that show what impedance adding the ferrite will bring. Generally, the bigger the ferrite, the more attenuation it will provide.

author: Aaron D. Parks
author_rank: Contributor
timestamp: October 14, 2014, 12:52:38 pm
content: I used the FB43-110 from Bourns on a recent project. Digi-Key has them. It's similar to the Amidon FB43-101 which I think is pretty popular. I slipped them over some transistor leads and they were a good fit. If you're using bare wire, they might be a little bigger than what you need. Bourns has a -085 size that should be a closer fit on bare 22 AWG wire.Mine were type 43 material. You might want a different material for you application. This document has some nice curves:http://fair-rite.com/newfair/pdf/CUP%20Paper.pdf

author: tekman11
author_rank: Contributor
timestamp: October 15, 2014, 11:46:39 am
content: I'm looking for a bead from 50-100mhzthanks for your input
Ferrite Bead SMD Code - Page 1
Forum section: electronics / projects

author: LittleRain
author_rank: Contributor
timestamp: September 11, 2018, 02:31:28 am
content: I'm just trying to figure out all the components on the Arduino Leonardo, and I've come across a Ferrite Bead with 105 on it.Does the 105 mean its 1M ohm? Or is it for something other than resistance?Thanks

author: t1d
author_rank: Super Contributor
timestamp: September 11, 2018, 03:24:07 am
content: Typically,A "1"A "0"And five more zeros=1000000But, I must admit, that I do not know, specifically, for ferrite beads.

author: LittleRain
author_rank: Contributor
timestamp: September 11, 2018, 03:29:59 am
content: Lol thanks. I'm assuming its resistance, they seem to be sold by that value.And google is coming up blank for me.I do want to make sure before I order some parts.

author: DaJMasta
author_rank: Super Contributor
timestamp: September 11, 2018, 03:35:20 am
content: In my experience, ferrite beads generally aren't marked. Sometimes inductors will be, especially when larger, in that same coding patter (similar to what resistors and capacitors are marked with), but I don't think I've seen a ferrite bead that was marked. They're generally rated for an impedance (in ohms, but not at DC) at a specified frequency, so if there was a marking on it, it would either be some kind of manufacturer specific code or that.

author: LittleRain
author_rank: Contributor
timestamp: September 11, 2018, 04:14:24 am
content: Yeah I actually figured out it was a 1M resistor.The reason I thought it was a ferrite bead is because I was looking up theMH2029-300Y, which had numbers on it. Couldn't see the number in the pic, then I found 105 on the board so thought it may be it since its in the area it should be.Turns out its the resistor that's parallel with the 16mhz crystal.Since the bead in the pic has a number still means my question was valid, but I also just found out it is resistance, or impedance rather,in this datasheet(for a different bead).

author: DaJMasta
author_rank: Super Contributor
timestamp: September 11, 2018, 05:25:22 am
content: It's hard to tell from the size of the picture, but I think it's a generic picture of resistors and not of the ferrite beads in question. The shape is about right given the image in the datasheet, but I don't see any good real images, just renders.

author: bson
author_rank: Unknown
timestamp: September 11, 2018, 10:17:27 pm
content: If it's 0402 perhaps it's a TDK MMZ1005? If so the letter and three digits refer to the impedance at 100Ω. For example an MMZ1005D330CT has a 330Ω impedance at 100MHz and the 'D' refers to the material used. C is for the 100MHz characteristic, and T refers to tape packaging (how it's shipped, on a reel).
Ferrite Beads -- characterising and selecting - Page 1
Forum section: electronics / projects

author: essele
author_rank: Frequent Contributor
timestamp: February 03, 2021, 11:34:46 am
content: Hi,I'm doing a bit of reverse engineering and have a board with a ferrite bead that I assume is there for EMI reasons, so I'm just trying to understand a bit more about it. I have a nice new VNA (SSA3021X Plus -> SVA1032X thanks to this forum!) and I'm trying to use that to better understand the characteristics of the bead.My challenge is that when I measure the bead I get a response that kind of makes sense, but I can't seem to find any products anywhere that are remotely similar.My measurement technique (which could well be deeply flawed) is to solder the bead onto an SMA connector, then after a SOL calibration of the VNA (using a calibration set built with the same connectors), I use the smith chart view and export the data so I can plot impedance (see image attached) .. the blue line is the main value (not sure what this should be called, R?) and the orange line is ABS(j).I've done this with a known bead and get very similar results to the datasheet, slightly lower impedance across the board, but definitely within the right ballpark.The unknown one seems to have a pretty narrow band between 25Mhz and 45Mhz with a really high impedance of up to 4k ... I have found a few devices like the Vishay ILBB0805, but they are generally higher frequency and only up to about 2.4k max impedance.So my questions ...(a) is this a valid measurement technique, or have I just been lucky with the known bead?(b) does anyone have any pointers to a bead (smt, 0805 ish) that might have similar characteristics so I can experiment?Many thanks,Lee.
Ferrite Beads on Input to Diff Amp? - Page 1
Forum section: electronics / projects

author: Alaezae
author_rank: Contributor
timestamp: September 12, 2025, 04:05:23 am
content: I was reviewing some old designs from the company I work for and found the following circuit being used to measure a high-voltage motor driver design when I came across this voltage sensing diff amp on the output of a set of half bridges. For company reasons, I'll only post LTSpice images of the original circuit (labeled "Circuit" below).Notice the input ferrite beads on the differential input line. I was really baffled by this, since I'm not familiar with this technique. At first, I thought it was used to decrease ENBW to meet some noise spec. That doesn't seem to be the case though, as the ferrite beads only seem to reduce the 3dB point by around 4 kHz. They do appear to dampen some resonance which is present when they aren't included (around 3 MHz). All this being considered, the drive frequency of the driver is well under the 1 kHz BW of the diff amp entirely. I included AC simulation results with and without the beads.Does anyone know why these might be included here? I know ferrite beads are used as low-Q inductors to block RF and filter EMI. This application seems strange to me though.

author: KE5FX
author_rank: Super Contributor
timestamp: September 12, 2025, 05:02:58 am
content: Definitely sounds like an RFI/EMI safeguard. Some opamps tend to demodulate any RF in the general vicinity, causing all sorts of weird behavior. In those cases the designer needs to keep RF away from the input pins.

author: mtwieg
author_rank: Frequent Contributor
timestamp: September 12, 2025, 01:51:20 pm
content: Some engineers add ferrite beads as a matter of habit, I wouldn't assume they actually serve some function.Are you sure the ferrite bead model in LTspice actually resembles the real thing? I'm aware that newer versions of LTspice ship with some models from Wurth, unless you're actually using one of those in the design I wouldn't trust the simulation.Also there maybe other factors in the real circuit that aren't included in the simulation (i.e. extra capacitance at the opamp due to traces and wiring). It's possible that these things would make the ferrite beads' purpose more clear.
ferrite beads vs RLC? - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: November 30, 2017, 12:09:53 am
content: If the frequencies are limited, can a RLC filter be used instead (easy to design), so long the SRF of the L is high (these are more expensive then beads, but I don't care), and the inductor is high quality.This is to filter noise from a DDS chip, after the signal went from differential to single ended. The frequencies are ultrasonic, but I don't want to contaminate the up-stream components with microwaves.I have seen something like this used in a Wavetek generator, it filters the signal through a little board of HF parts before it goes to the filter.Do the little LPF modules have better performance? I found that the drift added(simulation) to the AC level is sub 1ppm/degree C, so long I design it like 1 octave above my frequency of interest.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 30, 2017, 12:42:13 am
content: Sure, why not? Or just RL as the C is usually undesired and incidental.It's not necessary for general signal applications, but if you need more accurate filtering, it's better to use real inductors than ferrite beads. In power supplies, it's required -- ferrite beads saturate over (depending on size) 10-200mA.Tim

author: CopperCone
author_rank: Super Contributor
timestamp: November 30, 2017, 01:41:35 am
content: I need to see the emissions of the DDS to decide filter order. Annoying to have to prototype that.I wonder if the emissions are temperature sensitive. A bit I bet. And different between batches. Could make things hard.I guess I should put the DDS in its own shield. And around the op amp, so the signal goes strait into the filter outside the shield, as its 200MHz clock. I feel like noise is going to get blasted into the power rails though, through the op-amp. I guess best bet would be to put another HF filter at the output, I guess a LCL filter to also block transients some, and external noise.Why all this? To do HP justice.The DAC output on my wavetek function generator is pretty bad, the upstream filtering makes it reasonable. (when I was repairing it I looked).Perhaps some filters on the power pins of the instrumentation amplifier (like 2 orders of magnitude above the frequency its doing) would help? Don't care about DC here, goes through a BPFHow much headroom does the power rail of a IA require in terms of impedance vs its operating frequency