hybridfree/eevblog-posts huggingface dataset:
Sensor suite for rolling gates / cages - Page 1
Forum section: electronics / projects

author: arte.sea
author_rank: Newbie
timestamp: October 06, 2025, 02:44:10 pm
content: Hi Folks,I have recently installed rolling cages (https://www.sunprotect.aluprof.com/en/offer/commercial-gates/bkrsk-commercial-gate) onto my house doors and windows as additional protection against burglars.Cages are controlled using HomeAssistant via KNX actuators.After several month of using this system, I have detected several critical problems I need to address using my smart home system:1)Sometimes cages get stuck when initiating move up or down. If this happens, I need to immediately stop the motor.2)Currently there is no safety feature to detect presence of obstacles in the window opening during rolling down of the cage. There is such system available from manufacturer that can be integrated into lowest segment of the cage, but it is cumbersome, requires substantial pressure on lower edge and has issues with integration into my environment. I need some other way to detect presence / obstacles and stop the motor.I would like to install a microcontroller integrated into my wifi network on each window protected with the cage and detect:a)Presence of rolling cage at fixed points at the top and bottom of the railing. I guess this can be done using low range proximity sensors. Because thickness of the cage changes between segments perhaps those sensors could even be used to detect if cage is moving.b)Some kind of detector(s) to detect fixed or moving obstacles in the window opening, those can be simple light barrier(s) or perhaps even radar sensor(s).Since installation is done on the outside, sensors would need to be weather and UV proof and as small as possible.Actual logic would be in HomeAssistant, it will ensure that sensors are online and issue KNX telegrams based on sensor values and desired action.What type of components and software would you advise for such use case?Thanks

author: PCB.Wiz
author_rank: Super Contributor
timestamp: October 06, 2025, 08:35:23 pm
content: Quote from: arte.sea on October 06, 2025, 02:44:10 pmWow, that's industrial level protection. Most people use fixed ornate metal grills.Quote from: arte.sea on October 06, 2025, 02:44:10 pmDoes the system not include over current sense ?Quote from: arte.sea on October 06, 2025, 02:44:10 pmMaybe a light beam ? - this looks well packagedhttps://www.aliexpress.com/item/1005005477163966.htmlQuote from: arte.sea on October 06, 2025, 02:44:10 pmInductive proximity sensors can work on Aluminum, with reduced range, you would need to experiment.A waterproof inductor in a tuned circuit would give an analog (frequency) output.Or maybe the light beam above can be used multiple times?
sensor system for a research rocket - Page 1
Forum section: electronics / projects

author: NeoRecasata
author_rank: Newbie
timestamp: March 29, 2014, 04:05:21 pm
content: I'm designing a sensor system for a research rocketIt will have these sensorsAccelerometerTemperatureRadiation -gieger counterAir quality -gas sensorAnd other sensorsCan anyone suggest helpful information

author: dannyf
author_rank: Super Contributor
timestamp: March 29, 2014, 04:57:03 pm
content: Light sensor;Light spectrum analyse;Air particulate sensor;moisture sensor;vabriation sensor;pressure sensor;sound sensor sensor / mic;current sensor;voltage sensor;...Nice design you have there, btw.
Sensor to ADC - OpAmp design - Page 1
Forum section: electronics / projects

author: raff5184
author_rank: Regular Contributor
timestamp: May 09, 2019, 04:32:54 pm
content: Hi,I'm following this tutorialhttp://www.ti.com/lit/an/slyt173/slyt173.pdfto design an OpAmp to be placed between a sensor and an ADC.On page 4, section "Determining resistor values", it says "Let RG = 27 kΩ". Why? How is it chosen?\Thank you

author: No.Mad
author_rank: Regular Contributor
timestamp: May 11, 2019, 01:04:40 pm
content: Hey raff5184,from my understanding the value 27k is basically put as an example of calculating the rest of resistances and the whole process of adjusting values to those accessible on market.If you compare it to E24 Series, resistor values like 21k, 51k, 270R and so on are widely available from any online shop or Ebay.So simply speaking: it was used as an example for calculations. You could put any value for Rg and calculate the rest as shown.Regards

author: MasterT
author_rank: Frequent Contributor
timestamp: May 11, 2019, 03:59:22 pm
content: R1 & R2 is a load for Vref. Compromise is to keep R1 R2 as low as possible, sinceQuote, and not to overload Vref. Basically, calculation is should be done in reverse, first select R1 R2, than take RG about 100x of R1||R2 (1% tollerance) and last step is calculate RF.
Sensor vs sensorless ESC starting torque - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: January 05, 2019, 09:29:52 pm
content: Just ordered one of those brushless 3-phase motor drivers that are commonly used in model aircraft, race cars etc. You can get ones for motors that have position sensors as well as sensorless ones that use the motor back emf for determining rotor position. The motor I have is about the size of a coke can and has three Hall effect sensors but I chose the sensorless type controller so I can try it out on any other motor too.The question is, if sensorless controllers are available, why do some motors still have position sensors? Do they have greater starting torque because of not having to be initially jiggled before rotation begins? Or might that initial jiggling be unacceptable in some applications and a clean start is important?

author: max_torque
author_rank: Super Contributor
timestamp: January 05, 2019, 09:54:07 pm
content: It mainly depends upon the load, rather than the motor.For a propeller, the torque at zero speed is (effectively) zero, and you don't care if it initially jumps backwards a bit as the speed controller first fires fully open loop. Because the torque is low at low speeds, an purely open loop commutation sequence is very likely to drag the prop along too, meaning enough speed can be gained to enable a high enough Bemf to be reached to enable the system to swap into sensorless closed loop control.For a motor say driving a car along, that's rather different! (there can be max torque at zero speed, and you don't want the car to jump backwards or forwards when you just want to inch forwards slowly......)It also can depend upon the motor control strategy being used. Simple block commutated controllers, or voltage controlled sinusoidal voltage control ones can get away with basic phase position sensing, whilst systems running advanced strategies, such as FOC are likely to have physical position measurement systems for improved accuracy and failure effects management etc
Separating power and signal ground - Page 1
Forum section: electronics / projects

author: anvoice
author_rank: Frequent Contributor
timestamp: August 29, 2018, 07:09:51 am
content: I was wondering if there is a best practice as to how to separate power and signal ground for a motor control application. I've attached a picture of the way I did it: I basically have a thin section of conductor (0.5mm thick) in a fairly arbitrary spot. Is that a reasonable way to do it, or should I redesign?
Seperating charged plates vs increased voltage - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: January 31, 2015, 11:22:47 am
content: Suppose we have a pair of charged metal plates 100mm x 100mm separated by 1mm and in a vacuum. What's more, the potential difference between them is just below the voltage where a spark would jump between them. Now suppose we gradually draw the plates apart. As a consequence of the reduced capacitance because of the increased separation, the potential difference increases. Will the voltage increase faster than the separation difference so that at some distance it will flash over?Also to be considered, the electrostatic attraction means we have to put some work into separating the plates so I expect this work would manifest itself in an even greater increase of potential difference than just by the reduction of capacitance alone. So, will it flash over at some increased separation distance ?
Seperating ground connections in battery charging PCB layout?? - Page 1
Forum section: electronics / projects

author: Nikos A.
author_rank: Regular Contributor
timestamp: May 23, 2021, 07:54:09 pm
content: Hi everyone,I design an evaluation board that supports a wireless charging receiver and a battery charger.I am using the BQ25100 battery charger from TIhttps://www.ti.com/lit/ds/symlink/bq25100.pdf?ts=1621796894488&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ25100I do not have a lot of experience in layout designing and I use to follow the recommendations provided in the datasheets. In section 11 of the battery charger datasheet, there are some layout recommendations. The first recommendation says:"All low-current GND connections should be kept separate from the high-current charge or discharge paths from the battery. Use a single-point ground technique incorporating both the small signal ground path and the power ground path"I attach two files where I have drawn the current loop for both schematic and layout (at least this is what I think the loop is) during charging. Also, I have highlighted the input and output nets of the battery charger. I think that I do not have any signals that could be affected by the charging return path. Nevertheless, should I keep separate grounds between battery (-) and the ground of the rest of the circuit?
SEPIC inductors located on top and bottom PCB layer. - Page 1
Forum section: electronics / projects

author: Psi
author_rank: Super Contributor
timestamp: November 27, 2022, 02:33:46 am
content: With regard to undesirable interactions, what are the considerations when locating two separate inductors in a SEPIC with one above the other on the top and bottom of the PCB?eg, should you use inductors with the same/different winding directions etc..(I know you can get dual/coupled inductors in one package but I don't want to limit myself to a 'specialized' inductor.)I think the answer is that they should always be the same winding direction, but just wanted to check.Flipping one upside-down for bottom layer shouldn't change anything from a winding direction standpoint.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 27, 2022, 06:23:12 am
content: The coupling factor will be negligible (~0.02 max?), at least for most sizes, assuming open types, even without inner planes shielding them.Tim
SEPIC Shock - Page 1
Forum section: electronics / projects

author: SuzyC
author_rank: Frequent Contributor
timestamp: November 10, 2021, 01:10:53 am
content: I am now studying how to design SEPIC convertors and have encountered two conflicting datasheet reference designs that seem to contradict each other regarding the polarity of the switching inductors (transformer). Which is correct? (They both are, according to the dots!)Since both inductors are identical and share the same core, a bifilar winding would be the easiest way to construct the transformer and the dots always match up in this case.

author: Buk
author_rank: Contributor
timestamp: November 10, 2021, 01:16:01 am
content: Are you being confused by the fact that the polarity of the secondary coil is different in the two diagrams?In both cases the dotted secondary terminal is grounded.
SEPIC versus 4 switch buck-boost DC/DC converter - Page 1
Forum section: electronics / projects

author: lordnoxx
author_rank: Contributor
timestamp: April 24, 2020, 07:18:20 am
content: Hi guys,I am recently reading in Maniktalas "Switching Power Supplies A-Z". And the author does a great job describing the whole world of buck-boost and boost-buck topologies.Even though there are some obvious differences in the basic circuits of a SEPIC and a 4 switch buck-boost DC/DC converter both do basically the same task.Well I already know that they differ in terms of switching losses (1 Mosfet for SEPIC versus 4 Mosfets for the 4 switch buck-boost) and that the 4 switch buck-boost is likelymore difficult to control around that area where VIN equals VOUT. And I am aware that the 4 switch buck-boost can be controlled in many different ways...such as to onlyclock the buck side when VIN>VOUT and vise versa. Probably the 4 switch buck-boost can also (depending on the control algorithm or control IC) be made bidirectional in termsof power flow. Both have the same transfer function (VOUT/VIN = D/(1-D)). And so on and so forth.But as already mentioned SEPIC or 4 switch buck-boost...both do basically the same task.So which one to choose for which application? Are there any differences I have not covered? Advantages/Disadvantages?

author: Weston
author_rank: Regular Contributor
timestamp: April 26, 2020, 06:47:11 am
content: Technically you can implement the buck-boost converter with two switches and two diodes. And you might see the SEPIC converter with a second switch replacing the diode for synchronous rectification and higher efficiency. The diode in the SEPIC converter will also experience recovery loss.The biggest difference is that the SEPIC converter requires two inductors. Inductors are often the largest and one of the highest loss component in power converters.Additionally, the switch in SEPIC converter needs a higher rating than the ones in the buck-boost, it sees Vin + Vout and experiences a current of Iout/(1-D) (also can be expressed as Iin/D).The SEPIC converter has control advantages because you only need to drive on switch and from my impression it seems to be used more in lower power designs / integrated switching regulators. Additionally, the SEPIC converter has continuous input current, which makes filtering easier, while the buck-boost converter can have discontinuous input or output current.For the buck-boost converter the Vin~=Vout case is a bit of a hassle to deal with but there are control schemes that add minor additional switching loss. Meanwhile, the switch in the SEPIC converter has to deal with twice the current at Vin=Vout. In high power applications the higher switch rating and the second inductor of the SEPIC converter can be a disadvantage. At high powers (i.e. cost) its less of an issue to add additional switches. I would say that the buck-boost converter has advantages at higher power levels.
Sequential switchback Drl turn signal led strip -flashes white before turning on - Page 1
Forum section: electronics / projects

author: Lollero2
author_rank: Newbie
timestamp: February 22, 2020, 08:07:21 pm
content: Hi,I'm doing a project where I'm adding sequential indicators to my mk6 Vw Jetta taillights.I'm planning on using the DRL function for reverse lights to increase the lighting when reversing.When turning on the light strips with 12v to the turning signal wire the lights flash white before turning yellow.This is a issue as I don't want the white lights to flash everytime I turn on the indicator when installed on my car.Below is a video showing the problem. It will show better if you lower the playback speed a little.https://youtu.be/kM1Rjn1QMzUMy knowledge of electronics is not enough to fix this issue.Below is a picture of the controller board. I would really appreciate if anyone could help me with this. I was thinking that could a resistor or a capacitor help with this?At the top the black is (-) for white and yellow. Red is (+) for white and yellow is (+) for yellow.At the bottom the black is (-) for white and yellow. Red is (+) for white and blue is (+) for yellow.

author: Lollero2
author_rank: Newbie
timestamp: February 24, 2020, 07:38:50 pm
content: Does anyone have any ideas? I would really appreciate all the help I can get.

author: TomS_
author_rank: Frequent Contributor
timestamp: February 25, 2020, 08:31:10 am
content: Is that the official controller for the light cluster or something you have added?More details on what modifications you have made or are trying to make including a circuit diagram might help.

author: Lollero2
author_rank: Newbie
timestamp: February 25, 2020, 04:14:39 pm
content: It's the controller that came with the led strip.https://www.ebay.com/itm/2pcs-Flexible-LED-Strip-DRL-Daytime-Running-Light-Sequential-Flow-Turn-Signal/283565464375?hash=item4205d19b37:g:zRUAAOSwxKNbmNMr
SERDES problems at higher frequencies - Page 1
Forum section: electronics / projects

author: AndrewHodgson
author_rank: Contributor
timestamp: April 12, 2022, 05:41:38 pm
content: Hi,I'm trying to help a friend out with a SERDES issue, but my knowledge of the problem is not great, so you'll have to forgive me if some details aren't very clear.Basically, they have a SERDES link between two FPGAs that fails when the comms frequency is increased to 6.25 GHz, it works Ok at 3 GHz.The FPGAs are supplied by two separate low jitter clocks (PLLs) that in turn are fed by a low frequency oscillator. When the FGPAs are fed by the same clock (PLL), the link works at 6.25GHz.My question is does this sound like it's related to jitter? The low frequency oscillators have a buffer prior to the PLL with a cycle-to-cycle jitter of 200 pS max. Is this jitter likely to be passed on through the PLL and cause issues with the comms link at higher frequency? My understanding is the receiver can tolerate about 0.5UI jitter so this figure would be in the right range to cause an issue?Any other thoughts would be much appreciated.Thanks in advance
Sergey Kubushyn tunnnel diode pulser - Page 1
Forum section: electronics / projects

author: alpher
author_rank: Frequent Contributor
timestamp: December 22, 2018, 06:18:05 pm
content: A goggle search reveals a fairly detailed description of a DIY version of Tektronix 067-0681-01 pulser developed by Sergey Kubushyn. The tekscopes group post mentions the photos being uploadded to "TD Pulser" album, here's the link to that post:https://groups.io/g/TekScopes/topic/diy_td_pulser/7651796?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,1140,7651796Try as i migh, I cannot find that album, I'm I missisng something obvious?Does anyone have a link to these pics?Really appreciate any pointers .

author: Tom45
author_rank: Frequent Contributor
timestamp: December 22, 2018, 06:47:09 pm
content: Are you a member of TekScopes?I found the photos from your link by clicking on Photos at the left and then search for Tunnel. Sergey's photos were at the top.

author: David Hess
author_rank: Super Contributor
timestamp: December 22, 2018, 07:05:41 pm
content: I did something similar but instead searched for "td pulser".https://groups.io/g/TekScopes/photosearch?q=td+pulserThat post is from before the forum left Yahoo so I think the organization got a little messed up. If you click on the photographs, they have a name and date assigned to them so it is possible to figure out exactly which are the correct ones.

author: alpher
author_rank: Frequent Contributor
timestamp: December 22, 2018, 10:14:57 pm
content: Solved, I joined the group and only then the left panel with the various links became visible.Despite what group description claims of attachments being visible to anyone, guess not.

author: pleiades
author_rank: Newbie
timestamp: August 24, 2022, 06:39:11 pm
content: Is still possible to view the photos, i just registered and cant seem to find that left pannel?
Serial 7 segment LED display, long signal line denoise - Page 1
Forum section: electronics / projects

author: calli
author_rank: Regular Contributor
timestamp: December 16, 2017, 04:02:21 pm
content: Hi,I salvaged this cool device (contains a serial LED 7 segment display) from garbage and have NO clue what it was. But it is cool, I keep it.However it worked well as I tested it out of its housing, but now with the long cable I suppose I need to denoise the signal lines.All what is in the cable is VCC/GND DIN (data), CLK and a Strobe STB directly connected to an Arduinos digital pins. What can I do to denoise the signals?Thanks,Carsten

author: hlavac
author_rank: Frequent Contributor
timestamp: December 17, 2017, 12:18:06 pm
content: For long lines you will probably want to go differential signaling over a twisted pair (cat 5cable?).Look at some RS485 transceivers.

author: calli
author_rank: Regular Contributor
timestamp: December 17, 2017, 12:20:47 pm
content: I assume the device worked for its (unknown) intended purpose with the given cable length. So as the other end of the device is not here, but I think they used some caps/resistors to make the signal more stable... I am looking for advice or even only some google keywords for my own research.Carsten

author: jaycee
author_rank: Regular Contributor
timestamp: December 17, 2017, 06:23:16 pm
content: Simple RC filtering would probably do.. as the speed of the signals is likely not very fast, you dont have to worry too much about bandwidth limiting effect. Try something like 100 ohms + 470pF to ground.

author: rstofer
author_rank: Super Contributor
timestamp: December 17, 2017, 10:12:59 pm
content: How long is the 'long' cable?Is there a possibility that the gadget uses 5V logic and the Arduino uses 3.3V? What kind of devices are inside the gadget. Chip numbers...

author: calli
author_rank: Regular Contributor
timestamp: December 18, 2017, 08:56:56 am
content: The cable is maybe 2 m "long". The Display is a PT6961 based serial 7seq-LED.The Arduino I used has 5V logic, the PT Chip also.My 20MHz scope (https://www.eevblog.com/forum/repair/hm205-2-vs-bitscope-dso-look-ma'-no-pixels/msg902679/) is a bit slow to get good readings so I am poking a bit in the dark here...Carsten
Serial Control of Vendor based Servo Amplifier - Page 1
Forum section: electronics / projects

author: rockbassist90
author_rank: Contributor
timestamp: July 22, 2014, 04:18:40 pm
content: Working on a project at work.A control interface to bridge between our system and a motion controller's architecture.Motion controller uses an RS-232 based ascii interface that's text based.With our serial interface it will send commands to the board, where the controller will mount and take input.Our interface should have direct communication with the device, I don't believe any additional serial device is require since ours uses ASCII text based commands as well.Some infocontrollerhttp://www.copleycontrols.com/motion/pdf/SEM-ds.pdfhttp://www.copleycontrols.com/motion/pdf/Binary-Serial.pdf
Serial Flash with/without WriteProtect and Hold Input - Page 1
Forum section: electronics / projects

author: fossil
author_rank: Contributor
timestamp: January 24, 2019, 03:14:22 pm
content: I was exploring 16MB flash for a custom ESP8266 board. I have come across flash chips which do not implement "write protect" and "hold" for "Dual SPI" mode.For exampleWinbond W25Q128FW implements WP and Hold.Winbond W25Q128JV does not implement WP and Hold.The ESP8266 reference designs use dual SPI mode with "write protect" and "hold".Do I need to stick with the ones which implement WP and Hold?Or, can I ignore the WP and Hold outputs of ESP8266 without any consequences?Note: I have attached the excerpt from datasheet(s) showing features and pins.

author: nsrmagazin
author_rank: Regular Contributor
timestamp: January 24, 2019, 06:32:04 pm
content: It depends on 2 problems:0. The pins still might need to be connected to GND or VCC in order for the IC to function properly.1. If the programming uses these 2 functions its bad. Otherwise you can freely disable them.

author: fossil
author_rank: Contributor
timestamp: January 25, 2019, 02:14:38 am
content: Quote from: nsrmagazin on January 24, 2019, 06:32:04 pmI am trying to find out if ESP8266 uses these ping for programming. It seems ESP8266 allows one to select the SPI mode for programming flash. I will verify and update the thread.

author: fossil
author_rank: Contributor
timestamp: January 25, 2019, 11:24:16 am
content: After some search on various ESP8266 forums, found the answer to my question.The attached diagram shows how to wire the flash to be able to repurpose the GPIO9 and GPIO10, which answers my question.The following paragraph is copied from the following link.If you want to use GPIO9 and GPIO10 you must lift flash pins (3 - WP and 7 - HOLD) and pull up to VCC, then you can use these GPIOs (9&10). When flashing firmware (for example with Espressif Flash Tool) you must select DIO mode or change it manually in firmware.If one wants to read the long answer here is the link to web archive as original site seems to be down.https://web.archive.org/web/20180115033652/http://smarpl.com/content/esp8266-esp-201-module-freeing-gpio9-and-gpio10
Serial Inteface for WZ5020L 20A 1000W Power Supply - Page 1
Forum section: electronics / projects

author: flywire
author_rank: Contributor
timestamp: March 10, 2021, 03:57:16 am
content: I have aWZ5020L 20A 1000W Power Supply- see:It's got an N76E003AT20 - an 8051 compatible uControllerhttps://www.nuvoton.com/export/resource-files/DS_N76E003_EN_Rev1.08.pdf. The components are tightly integrated and I'm not aware of any published serial connection information, although it seems to be provided for on the board near the screen/button connectors.Any ideas on how I can hack into it with serial control? I'd like to control it with an esp32.

author: Tony9671111
author_rank: Newbie
timestamp: November 30, 2021, 02:22:05 am
content: A little late but the communication to the WZ5020L Display is SPI on 3 lines at 3.3 volts.The 5 control signals to the board from the switches and encoder are just using a signal to ground, which are normally 3.3 volt floating signals from the board.The ESP32 Slave SPI software on GitHub works to get you started.
Serial interface for a vacuum fluorescent disply - Page 1
Forum section: electronics / projects

author: mojoe
author_rank: Frequent Contributor
timestamp: March 15, 2020, 05:01:38 am
content: A few years ago, some of you acquired some Futaba or Noritake VFD's from me, a friend of mine, or elsewhere. At the time, I threw together an Arduino library (with some help from a forum member), to make the displays more useful. Recently, I was cleaning out some junk, and came across the displays.These particular VFD's have a dumb 8-bit parallel interface, with no handshake lines. Only a Write Strobe is available, to tell the VFD it has a byte of data. Although the displays work fine, they require nine GPIO's in your project. I had a little time, so I thought I'd start on a simple serial interface.I mention this in the program comments, but I'll say it again here: Do not try to power the VFD from the Pro Mini. It cannot source enough current. Power both the Pro Mini and the VFD from an external 5V supply. If you don't, your Pro Mini will release it's magic smoke.The comments in the attached Arduino program explain why I chose to use a Pro Mini vs some alternatives. The attached picture shows the prototype, which is very simple. The photo also shows me testing the serial interface with an HC06 Bluetooth breakout board. Later, I'll make a board that plugs onto the 14-pin connector on the back of the VFD.When I have more time, I'd like to use the Pro Mini to make the VFD emulate an HD44780 LCD, so you could use the standard Arduino LiquidCrystal library. Until then, I thought I'd post what I have now, so others can make use of it.Edit: I meant to say a version of the LiquidCrystal library that is modified for serial output. The standard library only does 4 or 8 bit modes. Similar to the I2C version, but for TTL serial output.

author: TomS_
author_rank: Frequent Contributor
timestamp: March 21, 2020, 12:26:11 am
content: You could reduce pin count by using a shift register, like a 74x595. That would be only 3 pins: clock and data for the shift register, and the strobe for the display to tell it to load a byte.That can be either hardware driven using a SPI peripheral, or bit banged in software.

author: greenpossum
author_rank: Frequent Contributor
timestamp: March 21, 2020, 12:34:48 am
content: Aren't there standard modules for a couple of bucks that have I2C input and have parallel outputs for piggybacking onto LCD displays? Could those drive the VFD board instead?

author: edavid
author_rank: Super Contributor
timestamp: March 21, 2020, 01:13:23 am
content: Did you find a datasheet for the VFD module?
Serial load PLLs and LED displays requiring a bit load count not a multiple of 8 - Page 1
Forum section: electronics / projects

author: Scratch.HTF
author_rank: Regular Contributor
timestamp: October 10, 2025, 07:39:21 am
content: This concerns an interface (SPI like which for a microcontroller using hardware SPI mode requires a transfer of a multiple of 8 bits) with Clock/Data/Latch signals, and I am curious why such devices exist - around the 4 bit era, microcontroller memory was at a premium and one possible reason is to speed loading time (considering that the loading speed is relatively slow at the time) by not loading unnecessary bits to make the bit count a multiple of 8.

author: Buriedcode
author_rank: Super Contributor
timestamp: October 10, 2025, 04:43:39 pm
content: Some micro's have an SPI module with the facility to use an arbitrary number of bits per transfer - although you are correct in that most are 8/16/32 bits. I really dont' have much of an idea, except that perhaps older devices where silicon space was a premium - if a device only needed 13-bits config, then thats all they used. Also, for some SAR ADC's they use the SPI/microwire/serial clock for the conversion, so the number of clock pulses is tied to the resolution.On some devices you can use 2 byte transfers for 8<x<16 transfers, by right justifying the bits - since often its just a shift register, so the extra bits at the start (MSB first) just drop out the end of the shift register, and are only latched once the latch/CS line goes high.
Serial Logger with marker?  - Page 1
Forum section: electronics / projects

author: Chet T16
author_rank: Frequent Contributor
timestamp: August 27, 2013, 09:30:19 am
content: Any recommendations for a serial logger that will allow me to mark points in the log so I can check for events afterwards? Something simple like tapping the space bar would do.I'm sniffing a can bus and there is a huge amount of data so I'm looking to narrow down the range of IDs I'm looking at

author: nctnico
author_rank: Super Contributor
timestamp: August 27, 2013, 12:43:15 pm
content: Many years ago I visited a company which did a lot of CAN hacking for cars. They had written an application which shows each CAN address on a seperate line which the rest of the message behind it. With that application it was very easy to see which data did what like opening / closing a window, pressing the accellerator, etc. You could see the values change. IIRC they also had the possibility to filter the messages a bit further.

author: Chet T16
author_rank: Frequent Contributor
timestamp: August 27, 2013, 02:52:43 pm
content: That would be nice to have! Its an automotive can bus that i'm monitoring and it's next to impossible to pick anything out

author: Chet T16
author_rank: Frequent Contributor
timestamp: August 27, 2013, 03:39:46 pm
content: I've just seen termite has a plugin which will send data using the function keys, that should help a lot
Serial over infrared to RS232? - Page 1
Forum section: electronics / projects

author: ChristofferB
author_rank: Frequent Contributor
timestamp: January 01, 2016, 08:32:30 pm
content: So I'm restoring an old pentium 1 laptop, for use in microcomputer development (it has a serial and a parallel port-and runs DOS software)But it only has one serial port -and then an infrared serial/parallel port.So my question is:- Can you desolder the IR LED and Photodiode in that (I assume that's how it RX'es and TX'es) and just snap a connector on that for 3-wire serial?- Or could one just make a small IR RX/TX to RS232 box and use that as a stand alone device?What would you recommend?Thanks in advance and happy new year!--Christoffer

author: SeanB
author_rank: Super Contributor
timestamp: January 01, 2016, 08:50:51 pm
content: That IR port goes to a dedicated IR chipset, which then has standard inverted TTL level connections to the main south bridge chip. You can replace it using a bluetooth module, as they both work with 115k baud rates, though you will lose the functionality of some bluetooth functions, or just use a simple RS232 driver board with a single chip solution to give you a serial port without any handshaking.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: January 01, 2016, 09:56:07 pm
content: Great, then, that's the plan!Thanks!-Christoffer
Serial Parallel Crystal Quandary - Page 1
Forum section: electronics / projects

author: Pat Pending
author_rank: Regular Contributor
timestamp: February 15, 2014, 01:43:11 am
content: I have a 28.8MHz crystal in a parallel resonant circuit on the side of a tuner/mixer IC.From a dedicated OSC pin the frequency reads high by +57ppm.Few crystals could be this bad from which I'm thinking the rock was spec'd for series resonant.Spectrally both a weak series resonant frequency and a much stronger parallel resonant frequency can be seen ~ 2.5kHz difference.Question is how to get rid of the series mode of oscillation?

author: rfbroadband
author_rank: Unknown
timestamp: February 15, 2014, 04:16:51 am
content: which tuner IC do you use, part number of crystal and ext. C values?

author: KJDS
author_rank: Super Contributor
timestamp: February 15, 2014, 08:08:01 am
content: Has the crystal ever been dropped, or run hot, or not used for a long time?

author: Rasz
author_rank: Super Contributor
timestamp: February 15, 2014, 09:24:07 am
content: Im guessing RTLSDR
Serial Port data logging w/sub-second timestamps - Page 1
Forum section: electronics / projects

author: forrestc
author_rank: Unknown
timestamp: February 15, 2018, 11:44:27 pm
content: I am hoping to find a serial port (aka rs-232) capture program for windows which will log binary data *and* timestamp it with sub-second accuracy. Millisecond accuracy is fine (or as good as windows can handle it with built-in timers and the buffering of the underlying serial hardware). Delta timestamps are fine (i.e. how many ms since last character was received).The purpose is to be able to send this to a customer who will capture a whole bunch of streaming data from a device, and then I will replay it on this end in close to real-time, so that I can test software written to decode the timestream. I have a very old program called "serial data capture", but it doesn't run under modern windows operating systems and I don't seem to be able to find a newer version of it.I am ok if the software only captures the data, I can easily hack together something here to replay it. Of course, if the software accurately replays it with timing preserved that's a bonus.Any ideas? Most/all of the software I've found either doesn't timestamp in sub-second accuracy (which doesn't do me any good), or in the one case I found that the software claims to do sub-second timestamps and replay, the replay function doesn't preserve the timing, and the binary format they save the data into isn't documented and isn't easy to decode.

author: Rerouter
author_rank: Super Contributor
timestamp: February 16, 2018, 01:24:07 am
content: Saleae logic, atleast that is what i use for these situations, get them to hook it up, run teamveiwer and record

author: sokoloff
author_rank: Super Contributor
timestamp: February 16, 2018, 01:53:34 am
content: I used the Eltima Serial Port Monitor for a project where I needed to do some logging/interception of serial streams on a Windows machine. It worked pretty well. I didn't need precise timestamps, but wiki page seems to say it does have support for sub-second timestamping, as well as playback.I'm pretty sure there's a free few day eval/trial before you need to purchase.https://www.eltima.com/wiki/user-guides/serial-port-monitor/introduction-serial-port-mon.html(No connection with them.)

author: sokoloff
author_rank: Super Contributor
timestamp: February 16, 2018, 02:01:20 am
content: Looks like there's a free (with limitations on session length) tool that also says it has a high-resolution timestamp function (in the release notes):https://freeserialanalyzer.com/changelogNo personal experience using that tool, but if "free as in beer" is important (budget or philosophical reasons), that's another choice.

author: AlexxGreen
author_rank: Newbie
timestamp: March 23, 2018, 11:48:44 am
content: According to your advice I have downloaded a trial of Eltima's port monitor from their official web-sitehttps://www.eltima.com/products/serial-port-monitor/and can confirm that it timestamps data with the millisecond accuracy. However,first I had to tweak the settings for milliseconds to show up. FYI, it logs the actual time as well as the time since the last record.
Series 470 ohm resistor in RX TX line - ESP8266 design - Page 1
Forum section: electronics / projects

author: oruvanenakul
author_rank: Newbie
timestamp: February 12, 2017, 04:43:44 pm
content: I was looking at the Wemos D1 mini schematichttps://www.wemos.cc/sites/default/files/2016-09/mini_new_V2.pdf, there is a 470 ohm series resistor between CH340G RX TX line and ESP8266. Is it something related to impedance matching? What would be the effect if I remove this resistor? Why there is no series resistor in the USB data line? as discussed in this thread:https://www.eevblog.com/forum/projects/why-usb-data-series-resistors/

author: rstofer
author_rank: Super Contributor
timestamp: February 12, 2017, 05:42:37 pm
content: I think the resistors are there to protect the chip. The concept of Rx and Tx is pretty poor. Rx is an input, right? Or is it the signal that goes to Rx somewhere else? Same convoluted definition for Tx. Many chips have been bricked by connected up Rx and Tx backwards. An output driving another output seldom ends well.The resistors can also slow risetime and help eliminate reflections. Some FPGA boards have 330 Ohm resistors in series with EVERY signal that leaves the board. Besides taming reflections, they protect the chip.

author: oruvanenakul
author_rank: Newbie
timestamp: February 14, 2017, 08:08:18 am
content: Protection in the sense protection from the overvoltage or from connecting Rx to Rx? Also the series resistors for D+ and D- are not necessary always?Quote from: rstofer on February 12, 2017, 05:42:37 pmCan you provide any reference for this?

author: JPortici
author_rank: Super Contributor
timestamp: February 14, 2017, 08:48:50 am
content: Quote from: oruvanenakul on February 14, 2017, 08:08:18 amit is something related to impedance matching (source termination)

author: rstofer
author_rank: Super Contributor
timestamp: February 14, 2017, 02:44:55 pm
content: Quote from: oruvanenakul on February 14, 2017, 08:08:18 amTry Google... There are a ton of replies to 'series resistor to limit reflections'. Basically, the resistor slows down the rise time by limiting the current available to charge the circuit capacitance during switching.
Series and shunt wound motors powered by voltage and current sources - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: November 02, 2017, 04:05:33 am
content: Shunt wound motor with voltage source = fixed rpm regardless of voltage.Series wound motor with voltage source = revs to destruction.Shunt wound motor with current source = fixed rpm regardless of current.Series wound motor with current source =Note - not talking about permanent magnet motors here?

author: ConKbot
author_rank: Super Contributor
timestamp: November 02, 2017, 11:59:29 am
content: Series wound motor with a current source with infinite compliance driving it at a significant portion of it's rated current would rev to destruction, or flash over, or overheat also. The currents in the coils would of course be constant, making for a constant output torque, similar to a permanent magnet DC motor. The motor would accelerate till windage and bearing friction equalled that torque. In a "normal" motor that should be way beyond over-revving it, and the current source would just keep throwing more and more voltage at it as the BEMF increased.A current source with limited compliance would just hit it's upper limit and become a voltage source, field weakens, you know where this goes.
Series diode to reduce supply voltage - Page 1
Forum section: electronics / projects

author: sebmadgwick
author_rank: Regular Contributor
timestamp: October 13, 2013, 01:54:19 pm
content: I have a 7.4 V battery and want to power RC servos with a max of ~6 V, the peak current might be something like 1 or 2 A; continuous 0.5 A. The simplest solution seems to be a series diode with a forward voltage of 1.4 V. However, finding a part is not as easy as I expected.I have been browsing diodes but datasheets seem to only list the "maximum forward voltage". I'm interested in the max and min forward voltage. Something like the 1N5391 seems great but I'd like to understand a bit more about what voltage drops I might see in practice.What do you think? Thanks in advance!

author: dannyf
author_rank: Super Contributor
timestamp: October 13, 2013, 02:05:20 pm
content: Datassheets typically provide a V/I curve that provides the information you want.The minimum voltage drop over a diode is 0.

author: madires
author_rank: Super Contributor
timestamp: October 13, 2013, 02:11:09 pm
content: Silicon diodes got a voltage drop of about 0.7V. For 1.4V you can put two in series and just have to select diodes matching the current. There should be a graph showing the voltage drop vs. current in the datasheet.

author: Bertho
author_rank: Regular Contributor
timestamp: October 13, 2013, 02:15:48 pm
content: The forward voltage of a diode is dependent on the current. Most datasheets include a graph that show forward voltage versus forward current. The forward voltage of normal silicon diodes is between 0.6V (low current) and 1.2V (high current).If you need a stable voltage, then a diode is not an optimal solution if the current varies. However, you normally see 0.6V..0.8V drop within reasonable bandwidth of current.You do need to have a diode that can cope with the current. It needs to have a higher max. forward current rating than that you's need. The second thing is that you need to get away with the power dissipation. A diode with 0.7V forward voltage and 2A of current dissipates 1.4W and that becomes heat.The diode you mention, 1N5391, has a forward voltage of 0.86V..0.95V at 0.5A (just under 0.5W dissipation at those parameters). The thermal properties are Rja = 60 deg/W, so you will see about 30 degree increase above ambient temperature if you just put it in.

author: sebmadgwick
author_rank: Regular Contributor
timestamp: October 13, 2013, 03:00:38 pm
content: Thanks for the replies. The graph has all the info (e.g. Fig 3here). It looks like a couple of 1N5391 in series could do the job. They would drop:1.2 V at 10 mA2.0 V at 1 A2.2 V at 3 A (although IFmax = 1.5 A)The supply doesn't have to be stable. In the past I have poweredHS-422servos directly from a 7.2 V which seemed to be a common arrangement, the higher voltage results in faster motion and greater torque. I expect the newer servos I now intend to use (HS-485HB) will behave the same. Perhaps my design could advise that one or both the diodes be instead populated with a jumps for 'optional higher servo voltage'
Series of 3-legged "3011 Standards"??? - Page 1
Forum section: electronics / projects

author: ledtester
author_rank: Super Contributor
timestamp: June 04, 2025, 06:49:41 pm
content: Does anyone have a clue as to what these are?They are like 4 rows of them - each serially numbered.Are they all the same device?Seems like only #6 and #7 are missing.

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: June 04, 2025, 07:11:37 pm
content: My best guess these were samples, requested by an OEM to make a statistical distribution analysis of the voltage, which would determine which of all the listed vendors should be the preferred one and which the alternate.But it is only a guess.

author: Kurets
author_rank: Regular Contributor
timestamp: June 06, 2025, 10:31:01 am
content: 2N3011 is a small signal NPN, usually in a TO-18 case but presumably it could also be requested in TO92 for a large customer. If you test one you should be able to determine what it is.

author: ledtester
author_rank: Super Contributor
timestamp: June 07, 2025, 11:43:44 am
content: Quote from: Kurets on June 06, 2025, 10:31:01 amI brought my transistor tester to the store and tested one of them. It tested as a NPN so you're probably correct.I tried removing one of the labels but was unsuccessful. Probably could do it with a fine point tweezers.My initial impression was that the number labels were added by the manufacturer as part of the device spec. but now I doubt that.
series pass element - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: January 04, 2014, 02:50:41 pm
content: Hi guys,I am working of a power supply. It works nice well, but I have some dought. I used N channel mosfet a series pass element. The gate is driven by a microcontroller via a transistor amplifier for a gain of 3. The amplifier is fed with a 18v via a dc to dc converter. by varying the gate through the mosfet conduct nicely. The mosfet is fed with 25V from a rectifier.my question is the gate voltage in the datasheet is given with respect to source Vgs, but at full conduction the mosfet source is at around 24V , but by giving around 15V from the amplifier with respect to ground the mosfet conducts pratically , but I am not able to understand it. somebody please explain

author: sleemanj
author_rank: Super Contributor
timestamp: January 04, 2014, 09:29:14 pm
content: Have you confused drain and source? It's easy to make that mistake. In the normal configuration, for an N-channel, the Source is closest to ground (and for a P-channel, source is closest to V+)

author: nickm
author_rank: Regular Contributor
timestamp: January 04, 2014, 10:14:00 pm
content: If the mosfet was truly on the drain and source would be at the same voltage referenced to ground (25V) and the gate voltage would need to be around 5V higher than the source voltage (30V with respect to ground). It sounds like your gate voltage will never be high enough to turn on the fet so it is probably conducting through the intrinsic diode which would explain the 1V drop.