hybridfree/eevblog-posts huggingface dataset:
Lightning Cable off Buck Converter - Page 1
Forum section: electronics / projects

author: jc0r
author_rank: Newbie
timestamp: January 25, 2020, 01:33:20 pm
content: Hi all. I am trying to make a custom project that contains an iPad that uses the lightning connector. I am trying to charge the iPad from a buck converter that outputs the correct 5v. Opening up the lightning cable, i have connected the red to the 5v and the black to negative. However, whenever i plug this in it will not charge. I have checked the pinout and it is indeed outputting 5v across pins 5 and 1. Anyone know what i am missing?ThanksJohn

author: coromonadalix
author_rank: Super Contributor
timestamp: January 25, 2020, 01:47:44 pm
content: If i recall in some Apple cable(s) you have id chip, if its not present it wont accept a charge

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 25, 2020, 02:09:58 pm
content: Short the data lines to each other.

author: jc0r
author_rank: Newbie
timestamp: January 25, 2020, 04:45:20 pm
content: Many thanks NiHaoMike, worked perfectly. Thankyou

author: PTR_1275
author_rank: Frequent Contributor
timestamp: January 25, 2020, 05:07:42 pm
content: Apple use different voltages on D+ and D- lines to tell the device how much current the charger can provide.Have a google for the different usb data line voltages

author: wraper
author_rank: Unknown
timestamp: January 25, 2020, 05:16:39 pm
content: Quote from: jc0r on January 25, 2020, 04:45:20 pmIt worked but most likely charging will be very slow. Likely at 500mA current.
Lightning Protection circuit for Ethernet - Page 1
Forum section: electronics / projects

author: jcosper
author_rank: Contributor
timestamp: September 22, 2016, 03:47:05 pm
content: I need to design a lightning protection circuit for an 10/100 ethernet port. I was looking at some of the guidelines, but wanted some input from the forum on what has worked for them. I was planning on using a circuit suggested from the ST SLVU2.8 datasheet:http://www.st.com/content/ccc/resource/technical/document/datasheet/98/f5/6c/77/ae/5d/4a/5c/CD00246363.pdf/files/CD00246363.pdf/jcr:content/translations/en.CD00246363.pdfThoughts?

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 22, 2016, 03:48:34 pm
content: Use a pair of cheap Wifi routers programmed to connect to each other.

author: Ian.M
author_rank: Super Contributor
timestamp: September 22, 2016, 05:44:28 pm
content: ..... or a pair of cheap fibre media converters and a run of fibre if you need better security or resistance to EMI.

author: dom0
author_rank: Super Contributor
timestamp: September 22, 2016, 06:24:56 pm
content: Quote from: Ian.M on September 22, 2016, 05:44:28 pm+1100BASE-FX media converters are essentially free today and quite often found for this exact purpose in labs and test stands.

author: _Andrew_
author_rank: Regular Contributor
timestamp: September 22, 2016, 06:39:28 pm
content: You did not mention the reason you have need for lightning protection for cat5.There are plenty of general surge solutions out there for rj45 connectionsIf it is for wifi gear mounted outdoors on a pole, mast or tower then it is a bit more involved as you will need to look at the earthing arrangements for the bit of metal of the structure it is bolted on to.This may be a worth looking athttps://www.dehn.co.uk/en-gb/lightning-protection-guide
Lightning protection considerations for a roof mounted GPS antenna - Page 1
Forum section: electronics / projects

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: February 12, 2020, 09:21:16 pm
content: I'd like to mount a GPS antenna for both gpsdo and as an rtk base station on my roof.For both applications it should have an open, unobstructed view of the sky. The house has lightning protection fitted and there is a cut down to the roof level antenna mast (for old TV antennas) on the very top, which is already attached to the lightning system. So far so good for the lightning arresting part I guess(?)However, what kind of protection do I need on the inside? As far as I could gather there should be an earthing point right after entry into the house. Something of that kind:https://www.amazon.com/Lightning-ARRESTOR-Ham-Base-Antennas/dp/B01LYK5TU5However, I did not really find anything for the frequency range in the ham space nor do the WLAN / amazon type arrestors in the +/-20 bucks range look particularly trustworthy(?)Also, where the antenna rod goes inside, there isn't really an earthing connection available. Would I just run a 2.5mm2 PE cable from the next outlet / distribution box to the surge protector (about 10m and from there another 15m down to the houses earthing point).I guess an additional arrestor / overvoltage protection circuit would also be in order since the arrestors I've seen so far in the ham space seem to work with gas discharge tubes and I do not think a gps module likes >50V on it's input

author: Johncanfield
author_rank: Regular Contributor
timestamp: February 12, 2020, 11:31:43 pm
content: Take a look at kf7p.com, he has military grade lightning protection in SO-239 or N connectors, also entrance panels, etc. An excellent resource is ARRL's Grounding and Bonding for the Radio Amateur book. Another resource for lightning and grounding parts is dxengineering.com.John, WB5THT

author: Simon
author_rank: Unknown
timestamp: February 13, 2020, 07:37:16 am
content: Please do not double post.
Lightning protection for GPS antenna - Page 1
Forum section: electronics / projects

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: February 12, 2020, 09:20:31 pm
content: HiI'd like to mount a GPS antenna for both gpsdo and as an rtk base station on my roof.For both applications it should have an open, unobstructed view of the sky. The house has lightning protection fitted and there is a cut down to the roof level antenna mast (for old TV antennas) on the very top, which is already attached to the lightning system. So far so good for the lightning arresting part I guess(?)However, what kind of protection do I need on the inside? As far as I could gather there should be an earthing point right after entry into the house. Something of that kind:https://www.amazon.com/Lightning-ARRESTOR-Ham-Base-Antennas/dp/B01LYK5TU5However, I did not really find anything for the frequency range in the ham space nor do the WLAN / amazon type arrestors in the 20-20 bucks range look particularly trustworthy(?)Also, where the antenna rod goes inside, there isn't really an earthing connection available. Would I just run a 2.5mm2 PE cable from the next outlet / distribution box to the surge protector (about 10m and from there another 15m down to the houses earthing point).I guess an additional arrestor / overvoltage protection circuit would also be in order since the arrestors I've seen so far in the ham space seem to work with gas discharge tubes and I do not think a gps module likes >50V on it's input

author: trobbins
author_rank: Frequent Contributor
timestamp: February 13, 2020, 03:50:36 am
content: Perhaps a sketch of all the parts and cables and equipment you have described would be so much easier to appreciate and then make comments on. That should also include an expected path that transient currents would take, and include the mains power distribution and how that gets back to earthing points and where it could be susceptible to transients coming in from other circuits that may receive lightning ingress, and where earth potential rises could originate.

author: BravoV
author_rank: Super Contributor
timestamp: February 13, 2020, 04:48:08 am
content: I'm no expert, its just this is current my setup.This is what I'm currently use ->PolyPhaser DGXZ-06NFNF-A, as its designed to pass DC bias voltage 5 V for the antenna's LNA, and suitable for GPS freq @ 800MHz up to 2.5 GHz.They claim its capable to withstand multi strikes without the need of replacing the GDT tube as in ordinary types.Took few photo shots when I received them.Below is the recommended lightning protection scheme and illustration from HP 58503A/B GPSDO manual on the wirings, watch carefully the ground wirings, there two earth connections, and joined at some place at the ground, pointed by red box.
LightServer: RGB Intelligent Lighting Project - App Control - Works with WS8212B - Page 1
Forum section: electronics / projects

author: remixed123
author_rank: Regular Contributor
timestamp: July 22, 2015, 11:26:12 am
content: Hi Everyone,I have made available binaries and source code for an RGB intelligent lighting project called LightServer that I thought some of you would be interested in.The best way to see what you can do with LightServer is to view the videos on Vimeo here -https://vimeo.com/album/3015956No coding experience required to set this up and use.Technical DetailsLightServer uses the Tiva C LaunchPad and the CC3100 Wi-Fi BoosterPack and a custom BoosterPack (Eagle files included – though you could get it to work without if you wanted).You also use standard WS8212B RGB LEDs like the NeoPixels from AdaFruit or the Flexi-Strip from Seeed Studios or from many other places.Please post your support questions here -http://forum.43oh.com/topic/8714-lightserver-rgb-intelligent-lighting-project-app-control-works-with-ws8212b-leds/Source Code and BinariesAll details are available on Github to get you started.Binaries and all other resources (All setup steps included) –https://github.com/remixed123/LightServer_Resources/wikiSource Code (All setup steps included) -https://github.com/remixed123/LightServer/wikiThe code is written in C and uses TI-RTOS, you will find in the code lots of lighting algorithms and many other features that could be used in your projects. If you do not want to code, then you can just use the binaries.Controlling LightServerWhat makes LightServer special is a number of iOS apps that are available on the Apple App Store that enable you to control the lights in various ways –https://itunes.apple.com/us/artist/glenn-vassallo/id914825403LightKit RGBis an all in one lighting control app with many lighting control featuresLightDrumis an interactive light and drum appLightTunesis a dedicated music synchronization appLightServer Packincludes all of the aboveDon’t worry if you do not have an iOS device, or do not want to get the apps, you can control the lights via the HTML pages (see attached image) that are on LightServer, but you do not get some of the cool features which require an App to function. Music synchronization, multiple device control and so on.Here are some screen shots of the appsPlease share with others who may be interested :-)Glenn.
Limit average input current (buck converter) - Page 1
Forum section: electronics / projects

author: JJalling
author_rank: Unknown
timestamp: June 04, 2019, 09:21:47 am
content: Hello,I'm trying to create a small circuit (3.3v) to interface my electricity meter wirelessly.The meter has a serial port, and can also provide power for my circuit. The datasheet specifies 4V+- 250mV at 75mA.My idea is to charge up a capacitor to handle the current spikes of the wireless module so I won't exceed the 75mA current limit.What is the best approach to do this? I don't want to trigger any alarms in the meter by drawing too much current from the port.How would you do it?edit: buck, not boost converterThanks, Jonas

author: ptricks
author_rank: Frequent Contributor
timestamp: June 04, 2019, 12:05:00 pm
content: If I understand you right you want to use something like and esp8266 as a wireless serial port to send the data and the supply is limited to 75ma ?Things like the esp8266 use more current when transmitting so you can use a capacitor like you suggested but you need current limiting also in there somewhere.If it were me I would figure out the max current that I need , 170ma + 10% overhead for the esp8266, so 177ma , or about 180ma.180ma x 3.3v =.594 watts is what we need. 75ma x 4v = .300 watts is what we have supplied.I would limit the current with a resistor then zener the voltage to 3.3V and charge a supercap. Should enable you to remain in high power mode for a few seconds before needing to go to low power.In the circuit below you may want to increase the resistor to 60 ohms to stay within the 75ma supply limit, the higher the value the less on time you will have to transmit as the capacitor time to charge will increase. I chose 30 because it will allow the quickest charge time but will cause a very brief current spike when connected and most supplies can handle that fine.

author: ogden
author_rank: Super Contributor
timestamp: June 04, 2019, 12:16:23 pm
content: Some switching regulator chips have input current limiter. Most popular example of such regulator is MC34063A.

author: David Hess
author_rank: Super Contributor
timestamp: June 04, 2019, 02:19:54 pm
content: Also, some switching regulators intended for battery charging have a separate input current limit. Or input current limiting can be added to an existing switching regulator controller.
Limit charge level for wireless keyboard built-in battery - Page 1
Forum section: electronics / projects

author: PeterMadach
author_rank: Contributor
timestamp: November 21, 2024, 02:03:10 am
content: Hello All,I have a rechargeable wireless keyboard (Keychron K2 V2 ISO RGB) which seems to have killed it's battery, or at least it started killing it. When it is plugged in to cable the charging Led keeps blinking and also makes its backlight flicker which is super annoying. I took it apart and measured the voltage which sits at 4.1V, which seems like the turning point where the charging circuit wants to give it some boost, I guess the pack cannot handle higher voltages for long. It did not look swollen tho. Nevertheless the solution for the issue seems pretty straightforward, just swap it to a new one, but I'm not too happy that the keyboard kills a battery in less than 2 years. Since I use my keyboard almost all the time in wired mode, my best guess is that the reason why this happened so quickly is because the charging circuit keeps it in high charge all the time, so I was wondering if there is hardware based solution which I can use to limit the battery charge to somewhere between 50-80%? Unfortunately there is no way to limit the charge level in software/firmware.
limit opamp's positive slew rate - Page 1
Forum section: electronics / projects

author: exe
author_rank: Unknown
timestamp: January 30, 2023, 05:28:20 pm
content: Hi there,I'm designing a fast low-current low-voltage power supply (say, max 20V, 0.5A output). I was curious how can I make it switching between CC/CV modes very fast. So, I experimented with a shunt topology. It works well except for one thing: when load is suddenly removed there is a short spike on output. It is caused by voltage regulating opamp not being fast enough (even with clamping diodes)So, I'm thinking if I could slow-down the rising edge of opamp, then there won't be any overshoot. The question is, is there a simple method to do so. What I tried:1) with lm108 a capacitor from compensation pin to output did the trick.2) With NE5534 (which I'm more likely to use) I was able to do something similar. But the capacitor needs to be discharged (so there is a shunting resistor), and it also needs a diode. The resistor creates an error, so precision is compromised.So, any other suggestion how I can slow down the rising slew rate of an opamp?

author: Kleinstein
author_rank: Super Contributor
timestamp: January 30, 2023, 05:47:09 pm
content: The problem is not that the voltage regulation is to fast, but it is too slow. While in current limiting mode the 20 pF capacitor gets charges some 2 V higher than wanted for the regulated state. It should help somewhat to remove the LED and detect the CC/CV state separately.One may get around the problem by adding a differential component to the regulator, so going from PI to PID. This would be some RC series element (e.g. 1K+1nF as a crude start guess) in parallel to R2. A little resistance in series with C1 can also help.

author: exe
author_rank: Unknown
timestamp: January 30, 2023, 08:09:49 pm
content: OMG, that absolutely worked! Thanks a lot!
Limit Push Button Digi Pot Output Resistance ( Maxim DS1809-10 ) - Page 1
Forum section: electronics / projects

author: interrupted
author_rank: Newbie
timestamp: August 13, 2017, 12:58:12 pm
content: Hi,like the Threadtopic already says, i am looking for a way to limit the Output Resistance Range from a Maxim DS1809 IC which supports up to 10k Output Resistance. The Application Notes dont say anything about this, by myself i was only able to archive it "somehow" with parallel hooked up fix Resistors. Which turned out as an absolut stupid idea which wont work.Reducing the Output Range from 10 to 5k without adding a non linear behavior is something i am looking for. Maybe i should try 2 of the DS1809 Stacked to half the output.But, i am pretty sure that its not needed to go that ugly way. Maybe anyone got a hint how to archive this?Spec Sheet for the IC ishttps://datasheets.maximintegrated.com/en/ds/DS1809.pdfThanks!Juergen

author: danadak
author_rank: Super Contributor
timestamp: August 15, 2017, 11:59:52 am
content: What is the 1809 controlling, what is its variable R being used in restof solution ?One possibility, convert the pot voltage to a current source with OpAmp.Again depends on answer to above question.Regards, Dana.
Limit switch - help find one - Page 1
Forum section: electronics / projects

author: metRo_
author_rank: Regular Contributor
timestamp: August 28, 2013, 10:11:47 pm
content: Hi,I'm looking for a limit switch but it won't cut a power source connection. I'll use it as a input for microcontroller to know when a moving piece reached the final position so I don't need nothing rated for several amperes. The smaller one I found ishttp://www.e-switch.com/product/tabid/96/productid/94/sename/ts-series-sub-miniature-snap-action-switches/default.aspx#ex1Do you know any other options like that or smaller? Another option are the ones used in cdrom/dvd players but I can't find a image of them right now but they are just a plastic piece hold two pieces of copper, do you know them or how they are named?Thanks(sorry my english :s)

author: SeanB
author_rank: Super Contributor
timestamp: August 29, 2013, 04:38:11 am
content: You will not get microswitches much smaller than that, and if you want leaf switches I would just gut a few CDROM drives for the tray switches, and use them.If you need a precision switch then it will be a lot more expensive, depending if you are happy with a final position error in the order of 0.5mm or not. If you want a very precise switch they do become rather expensive as you go to finer and finer resolution.

author: metRo_
author_rank: Regular Contributor
timestamp: August 30, 2013, 12:22:10 am
content: Quote from: SeanB on August 29, 2013, 04:38:11 amthanks, the term "leaf switch" will help me

author: george graves
author_rank: Super Contributor
timestamp: August 30, 2013, 05:44:10 am
content: You can also use a hall effect switch. Such as:There are from reprapdiscount on ebay.

author: metRo_
author_rank: Regular Contributor
timestamp: September 09, 2013, 10:49:33 am
content: Thanks, but I need something small:)

author: george graves
author_rank: Super Contributor
timestamp: September 09, 2013, 12:25:34 pm
content: The hall effect sensor is a t-92 package(I'm sure you could extend them off the board). And those tiny magnets are tiny. Can't get much smaller I'm afraid.Other wise you might look for a momentary tactile switch with only 2 pins. They are half the size of a normal tac switch.
Limited availability of JST XH SMD connectors? - Page 1
Forum section: electronics / projects

author: amaschas
author_rank: Regular Contributor
timestamp: July 11, 2024, 09:49:03 pm
content: So I recently went on a search for what I thought was a very widely available connector in the US: a JST XH SMD female header with 5 pins (S5B-XH-SM4). Looking on Digikey, only the 4 and 6 pin versions are available, and Mouser barely has any JST header products available at all. Does anyone know what's up with these products? I can get knockoffs from China pretty easily, but I'd like to buy the real thing if I can.

author: thm_w
author_rank: Super Contributor
timestamp: July 11, 2024, 10:33:25 pm
content: JST doesn't make them:https://www.jst.com/products/crimp-style-connectors-wire-to-board-type/xh-connector/Either use the 4 pin, 6 pin, or use the through hole version (S5B-XH-A).If its a hobby project just buy from china.

author: amaschas
author_rank: Regular Contributor
timestamp: July 12, 2024, 04:27:19 am
content: Ah, interesting! That's sort of frustrating, but good to know. Chinese connectors it is then!
Limiting current to a stepper motor - Page 1
Forum section: electronics / projects

author: jwhitmore
author_rank: Regular Contributor
timestamp: October 14, 2016, 08:09:54 pm
content: I just started experimenting with a micro-controller connected via a Texas DRV8833 Dual H Bridge Motor driver chip to a stepper motor. All was going well, I was measuring the output voltage from the H Bridges, until I connected up my actual stepper motor. I'm only using a 600mA Power supply, which I had lying about. As soon as I connected up the motor it's killing the voltage to the micro-controller.So obviously my power supply ain't got the juice needed, but then I got to thinking I only want this to turn the needle on a gauge I'm making. So it's not like I need torque so I could limit the current to the stepper motor. I had a look around and found an article  which while through maybe raises as many questions as it answers for me. The problem is that the article talks about wasted heat which seems to be the way to limit current. Whilst that obviously works it seems like a bit of a waste to be burning off energy for a needle in a gauge.It's not mentioned, as far as I can see in the DRV8833 datasheet, or  but can a resistor be put between the H Bridge output and the motor winding? Sounds simple so it's probably wrong but even if it is a stupid question I might learn something.http://homepage.cs.uiowa.edu/~jones/step/current.html

author: rob77
author_rank: Super Contributor
timestamp: October 14, 2016, 08:22:13 pm
content: just increase the value of current sensing resistors to limit the currentactually it is in the datasheethttp://www.ti.com/lit/ds/symlink/drv8833.pdfpage 8 - resistors on pins marked AISEN and BISEN

author: jwhitmore
author_rank: Regular Contributor
timestamp: October 14, 2016, 08:36:02 pm
content: Thanks a million for that I totally missed it.
limiting input voltage to LED driver ICs - Page 1
Forum section: electronics / projects

author: jmole
author_rank: Regular Contributor
timestamp: January 23, 2015, 05:19:22 am
content: I see that on a lot of linear LED drivers, they have a maximum LED Power supply voltage. On the surface, this makes sense, if you're controlling current with a MOS transistor. However, there are occasions where I'd like to use something like the TLC5940 to control 16 strings of LEDs, maybe with a supply voltage of 48V.Datasheet:http://www.ti.com/lit/ds/symlink/tlc5940.pdfI considered that maybe a Zener diode at the inputs would do the trick, but this is going to create a small current in the LEDs when they would otherwise be off, so isn't really the solution I'm looking for. Wondering if anyone else might have a clever solution.There are certainly other chips out there, but I haven't found any that do individual PWM dimming on multiple channels of high-voltage LED strings.

author: ajb
author_rank: Super Contributor
timestamp: January 23, 2015, 08:15:23 pm
content: The last time I was seriously looking at controlling a large number of LEDs I seem to recall seeing a number of multi-channel constant current drivers designed to be used with an external PWM signal, perhaps a setup like that would suit your needs? The trick then is providing a sufficient number of PWM outputs. If you only need 16 channels, you might be able to find a suitable micro with that many PWM outputs, or maybe an IO expander, or use the inverted output of the TLC5940, even. If you need more channels something like the LT8500 (48 channels, with some nice control features) might be a better fit.If you can get away without the constant current drive, then of course you could simply use the TLC5940 to control an external transistor.Thinking a little more out of the box, if you can arrange your circuit so that the TLC5940's Vcc is at +48V (with it's ground at +43V), then you could use a current mirror to turn its output current around and drive your LEDs from the high side. For higher currents that wouldn't be terribly efficient, though.
LIN Bus How many slave nodes can you have on one master? - Page 1
Forum section: electronics / projects

author: tru3533
author_rank: Regular Contributor
timestamp: January 11, 2018, 11:08:30 pm
content: I'm really stuck on this question:On the LIN Bus How many slave nodes can you have on one master? cant find it anywhere.This is what I know: 1 node can contain many IDsThe LIN bus provides a total of 64 IDs. IDs 0 to 59 are used for signal-carrying (data) frames, 60 and 61 are used to carry diagnostic data, 62 is reserved for user-defined extensions, and 63 is reserved for future protocol enhancements. The ID is transmitted over the bus as one protected ID byte, with the lower six bits containing the raw ID and the upper two bits containing the parity.I see some place 16 is mentioned, but it does not make sens to me. Any idea?

author: danadak
author_rank: Super Contributor
timestamp: January 12, 2018, 01:38:38 am
content: This seems to imply 15 -http://ww1.microchip.com/downloads/en/DeviceDoc/article_ac9_two-wire-lin-networking.pdfRegards, Dana.
LIN bus issues - capacitance? voltage drop? - Page 1
Forum section: electronics / projects

author: joeyjoejoe
author_rank: Frequent Contributor
timestamp: February 27, 2018, 12:12:48 am
content: I'm trying to talk to some devices on a LIN bus with an Arduino Uno and an MCP2003B. I'm reverse engineering an existing LIN master. (See :https://github.com/trainman419/bekant)Here's a shot of the schematic, before adding in diodes :The main issue - only 1 of the slaves is responding, the second one isn't. I have dumbed down the code to literally reading in from the two devices, and one responds, the other doesn't. So the first one responding confirms that my basic code/hardware is working. If I plug in the original master, both devices are working as intended.The only thing that makes sense at this point is the physical layer.This is the typical implementation of a master from the MCP2003B datasheet :I've added diodes (1N4148's) to the Vbat and LIN bus (Lbus) pullup. I've also tried different capacitor values on Lbus, based on some other material I dug up for other LIN interface chips. I've also tried different pullup resistor values for LBus. However, I'm sticking with 1k, as with 470ohm and 220ohm the slave devices stopped responding.I'm wondering if it's the further device that isn't responding. Some sort of voltage drop, and it's not hearing what's being sent? Mind you, the end of the bus is only 3 meters long. The voltage is provided by a 7812CV.I have a 1054Z on the way so I can scope the bus line to see if there's anything even coming back - can't logic prove the 12V LINBUS, only the TX/RX of the MCP2003B.Any thoughts or ideas? Some of the random things I keep thinking of are kind of voided by the fact that one of the slaves is responding. I think I'm in over my head here.
lin ldf software and general stuff - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: May 18, 2020, 06:36:58 pm
content: I'm looking to work with lin. I have an ldf file for the first item but it's double dutch to me even after reading the lin 2.2 spec. Is there a freely available program out there that will open these files and present them in a more human readable form?I am also generally confused about lin and how addressing works. with only 60 ID's hows does this thing even work? I see mentions of vendor, product and revision ID's but still how does this help me if I have two identical items that respond to the same ID?
Line Filter Design for Digital Circuit  - Page 1
Forum section: electronics / projects

author: amar
author_rank: Contributor
timestamp: May 14, 2013, 05:29:31 pm
content: Hi .. please suggest me how to design a Line filter for digital circuit to avoid EMI and RFI.I know .1uf caps helps a lot but i want to learn more better filteration

author: c4757p
author_rank: Super Contributor
timestamp: May 14, 2013, 05:41:16 pm
content: $2.84.Why bother?

author: amar
author_rank: Contributor
timestamp: May 14, 2013, 05:54:11 pm
content: thats better solutionbut i am using SMPS for Digital circuit .. any suggestion for LC filter

author: c4757p
author_rank: Super Contributor
timestamp: May 14, 2013, 05:57:24 pm
content: You mean on the output of the SMPS?

author: amar
author_rank: Contributor
timestamp: May 14, 2013, 06:05:15 pm
content: no ... for microcontroller
Line out to mic level adapter - Page 1
Forum section: electronics / projects

author: toto83
author_rank: Contributor
timestamp: March 03, 2018, 12:48:25 pm
content: Hello there,I made a preamp circuit which is functionnal using one of the two amps of a TL082 amp.It outputs a line level of +4dBu, about 1.730Vpeak.I would like to connect it to a PC mic IN, which means (if I am not wrong) that I need a -50dB attenuator.Can I build such attenuator from the op-amp?Thank you for your helpTom

author: Paul Price
author_rank: Super Contributor
timestamp: March 03, 2018, 04:28:51 pm
content: Just use two resistors to make a voltage divider, that's all you need.

author: toto83
author_rank: Contributor
timestamp: March 03, 2018, 10:58:22 pm
content: Is there any formula to go from attenuation to resistor?

author: DimitriP
author_rank: Super Contributor
timestamp: March 04, 2018, 12:18:47 am
content: Resistor values for attenuator calculatorhttp://www.nu9n.com/tpad-calculator.html

author: tooki
author_rank: Super Contributor
timestamp: March 05, 2018, 12:25:36 am
content: Quote from: toto83 on March 03, 2018, 12:48:25 pmFirst, check if the PC’s sound settings let you switch the input to line-level; most do, right in software.
Line voltage thermostat (e.g. HTM611A) - Page 1
Forum section: electronics / projects

author: leblanc
author_rank: Regular Contributor
timestamp: April 09, 2020, 06:44:35 pm
content: My house has baseboard heaters (electric heating). The thermostats switch the 240VAC directly. They're single-pole thermostat so one of the two lines is always energized. I'll called the switched one "L1" and the other one "L2".One of my thermostats is a programmable thermostat (TRIAC controlled). I figured it must be powered by putting a transformer across L1 and L2 (e.g. something like 240VAC to 12VAC, followed by a rectifier and then a DC/DC.However, when I looked at the user manual for it, I found that this thing only has an two wires, one for input (i.e. line voltage from the breaker panel) and one for the load. The other side of the load just goes back to the breaker panel to connect to L2 (well it goes back to the same electrical box as the thermostat first, but it doesn't connect to the thermostat).How would you speculates this thermostat gets powered internally?Hint: there is a 500W minimum load (and 3kW max).I see a few possibilities:The device only gets powered when the load is ON and we have some kind of Rogowski coil from which we take power. When the load is OFF, we run off a battery or supercap.The device only gets powered when the load is OFF and we just take our supply in parallel with the TRIAC (the load would be small enough that the load-side of the TRIAC is close to L2). When the load is ON, we run off a battery or supercap.The device uses a combination of the two and does not rely on a battery or supercapCan you sketch your guess of what the schematic would look like?I don't think it's #1 because you wouldn't want your heaters to turn on periodically in the summer. Although #3 would work the best, the added cost is probably not worth it. So I think it's #2.
Linear Actuator Controller for Robotic Platform - Page 1
Forum section: electronics / projects

author: Fratink
author_rank: Contributor
timestamp: March 09, 2017, 04:32:57 pm
content: Hey All,I'm a bit stuck trying to find a linear actuator controller that doesn't expect me to use a key fob. I would rather not roll my own solution if I don't have to but it's starting to look as though I might have to. I feel this must exist since robotic applications would certainly need something like it.Requirements are:Able to control 12V linear actuators up to 20APotentiometer input required so that actuator can be set to any lengthMust accept commands over some type of digital interface (Ethernet, CAN, serial, etc. are all good) to set actuator lengthDoes anyone have any suggestions?

author: sentry7
author_rank: Regular Contributor
timestamp: March 10, 2017, 01:23:33 am
content: I would checkRobotShop; they have wide assortment of robotics parts.

author: Fratink
author_rank: Contributor
timestamp: March 13, 2017, 04:48:55 pm
content: Hmm...Looks like all they have is a 4A controller. Too bad it can't do more as it looks like a good fit otherwise!http://www.robotshop.com/en/actuonix-linear-actuator-control-board.htmlThe search continues!

author: DaJMasta
author_rank: Super Contributor
timestamp: March 13, 2017, 06:44:56 pm
content: Don't know much about linear actuator drivers, but at least for one I had seen, they required a high current motor driver with a feedback input for servo control - you may not need something marketed as a linear actuator driver if you can find a high current servo motor controller. Pololu lists their JRK controller line as good choices for linear actuators they sell - could be worth a look.Not sure how early it will be to find an integrated potentiometer input, but if they're using a micro and it has a few user programmable pins, it may be real easy to add one.

author: Fratink
author_rank: Contributor
timestamp: March 13, 2017, 08:18:08 pm
content: DaJMasta, that's brilliant! I'd never thought of looking for something like that. I'll have to read the specs more but at a cursory glance it looks really promising!
Linear I2C battery charger - Page 1
Forum section: electronics / projects

author: gaminn
author_rank: Frequent Contributor
timestamp: November 24, 2019, 09:06:43 pm
content: Hi,I'm looking for I2C controlled 1 cell li-ion baterry charger with power path capability and with minimal external components. Input voltage is 5 V, charging current max 800 mA - 1 A.This device is exactly what I want:https://www.monolithicpower.com/en/products/battery-management/linear-chargers/mp2667.html. But I think it is not possible to buy it aywhere...Do you know a similar component?

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: November 24, 2019, 09:39:35 pm
content: What, exactly, do you want to control dynamically via I2C, instead of using programming resistors?If you are okay with 500mA charging max current, the bq25155 is a functional replacement for that MPS part, with "minimal' support components. It even comes with two LDOs built-in: a software-programmable 150mA LDO, and a fixed always-on 1.8V 10mA LDO. (EDIT: But it's BGA.)If you got rid of the linear topology requirement, you would have dozens of choices that meet your other requirements, just from TI alone, in relatively easy-to-use QFN packages.

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: November 24, 2019, 09:48:20 pm
content: For a non-BGA alternative, see the 500mA LP3947 in a 0.5mm DFN.

author: gaminn
author_rank: Frequent Contributor
timestamp: November 25, 2019, 03:19:57 pm
content: I don't have much space on my board, every component saved is plus.However, I ended with non-power path non-I2C BQ24040 - it needs 2 resistors and 2 capacitors only.
Linear Regulator - Regulating the negative rail? (NPN connected to the negative) - Page 1
Forum section: electronics / projects

author: Magnethicc
author_rank: Contributor
timestamp: May 11, 2025, 01:57:38 pm
content: Regarding:EEVblog #649 - Power Designs 2005 PSU Teardown -The schematic shows that the positive rail is always connected to the output and the regulation is by a bottom side NPN - like in the figure below:https://ibb.co/W4DNr3gHhttps://imgur.com/a/6uwht3MSo I was wondering -1. why is this not so popular arrangement? it seems easier to drive the NPN connected here and not at the positive rail, especially if one would use a NMOS.2. what are the drawbacks of regulating the negative rail rather then the positive rail?Thank you.

author: PGPG
author_rank: Frequent Contributor
timestamp: May 11, 2025, 03:01:11 pm
content: Supply (-) is frequently also used as reference for signalling (like OC, RS232 or not isolated RS485). In such cases regulating supply in (-) rail you lose this reference.

author: JoanBS
author_rank: Contributor
timestamp: May 11, 2025, 03:47:06 pm
content: I don't know any disadvantages. One advantage of these linear power supplies is that the collector of the output transistors can be connected directly to the heatsink/chassis without the need for insulation.

author: Stray Electron
author_rank: Super Contributor
timestamp: May 12, 2025, 12:29:19 am
content: I worked for Burroughs Corporation back in the day and I worked on many of their early desktop electronic calculators and they all used that type of linear regulator. NPN power transistors are (or were) cheaper than PNP power transistors and all of the raw DC power came from the secondary of a transformer so the DC rails were floating so there was no worry about ground loops or other potential problems.

author: David Hess
author_rank: Super Contributor
timestamp: May 12, 2025, 02:15:40 am
content: Quote from: Magnethicc on May 11, 2025, 01:57:38 pmGood power PNP transistors lagged power NPN transistors by years and were more expensive. The same applies to p-channel FETs. There was a brief time where power NPN transistors were silicon and power PNP transistors were germanium.Tektronix used that configuration in their linear regulators when the secondary was not floating, so NPN power transistors were used to generate both positive and negative supplies.As far as how popular it is, all of the common integrated negative regulators use it because integrated power PNP transistors are generally unavailable except at high cost. So this include all of the 79 series regulators, as well as the LM337 and related parts.QuoteThere are disadvantages:1. The output impedance of the common emitter transistor varies a lot more with load current than the common collector configuration where the output impedance is much lower. Combined with the output capacitance, this makes frequency compensation more difficult.2. The base current is lost, so efficiency is lower. With the common collector configuration, the base current adds to the output current.
Linear safety switch - Page 1
Forum section: electronics / projects

author: Rachie5272
author_rank: Regular Contributor
timestamp: July 29, 2016, 04:20:16 pm
content: I'm trying to figure out what a particular type of switch is called, and where to find it. It's a long thin strip, 1-2 cm wide, maybe 5 mm thick, and often a meter or two long. It's typically mounted on the perimeter of heavy machinery as a safety cutoff switch. If someone bumps into it, the machine power is cut.Mechanically, it's something like a venetian blind: a long curved piece of metal which deforms to contact a flat piece of metal.Does anyone know what this is?

author: helius
author_rank: Super Contributor
timestamp: July 29, 2016, 05:09:54 pm
content: One vendor calls them ribbon safety switches.https://www.tapeswitch.com/Info/Catalogs/Switch_v3.0.pdf
Linear scale resolution increase - Page 1
Forum section: electronics / projects

author: geshka
author_rank: Regular Contributor
timestamp: October 29, 2024, 08:00:31 pm
content: Hello folks.I've got my hands on linear scale with optical strip encoder and reading sensor made around Avago. HEDS-9720 with quadrature output. It is encoder that provides up to 150 LPI resolution according to spec, which makes it rather useless for precise measurements (like on mill or lathe) . There are, however, two sensors that are mounted in the same scale and they can be moved synchronously or independently - mechanically they are not connected to each other.My question - is there way to make it , let's say differential, move it synchronously but with some shift between each other, and then to increase resolution by subtracting signal in MCU? Any other bright idea ?Thanks.

author: moffy
author_rank: Super Contributor
timestamp: October 29, 2024, 10:02:44 pm
content: Could you please elaborate as to what the second sensor is?

author: thm_w
author_rank: Super Contributor
timestamp: October 29, 2024, 10:13:37 pm
content: Quote from: moffy on October 29, 2024, 10:02:44 pmSounds like its a second of the same sensor. In which case yes, you could offset it by 45 degrees and then read that into a micro to get 300 LPI.Is it worth the time, probably not, as thats still not amazing resolution.

author: TimFox
author_rank: Super Contributor
timestamp: October 29, 2024, 10:24:55 pm
content: Very high resolution linear encoders take the analog signals from two sensors 90oapart and do a mathematical interpolation between physical lines.See pp 18-21 of this Heidenhain brochure:https://www.heidenhain.us/wp-content/uploads/2022/07/PR_Interfaces_ID1078628_en.pdf

author: geshka
author_rank: Regular Contributor
timestamp: October 29, 2024, 10:27:00 pm
content: Yes, second sensor is exactly the same. Sure, still not a great resolution, but for the experiment sake... I was thinking following - quadrature encoder can give four transitions per one division on scale , so this is 150 x4 and then differential readings is another x2 which si already something... what do ya think ?

author: thm_w
author_rank: Super Contributor
timestamp: October 29, 2024, 10:35:34 pm
content: Yeah you are right, LPR would translate to 4x CPR so x8 as you say.Which would give a resolution of 1"/1200 = 0.0008" which is not too bad.Looks like there are also parts like TimFox is talking about to interpolate but you'd essentially be replacing the encoders:https://www.broadcom.com/products/motion-control-encoders/incremental-encoders/reflective-encoders/aedr-871x

author: mzzj
author_rank: Super Contributor
timestamp: October 29, 2024, 10:38:07 pm
content: Quote from: thm_w on October 29, 2024, 10:13:37 pmIndeed. Linear scales prices have dropped to dirt cheap compared what they used to be ages ago.Fully packaged 500mm linear scale with 5080 LPI or 0,005mm resolution is something like 50 usd and half of the price is already shipping fees. 0.001mm resolution is also commodity item, maybe 70 usd.
Linear speed control - Page 1
Forum section: electronics / projects

author: Kirigozo
author_rank: Contributor
timestamp: May 27, 2015, 11:30:12 pm
content: Hi folks,Found a circuit to do speed control on a low power AC motor without the usual problems of EMI. The problem is I can only find the one example (Silicon Chip May 2014) and important details are a bit scarse.The bridge and mosfet form a resistive element to control voltage so no EMI from fast rising and falling edges. Think of the load element as a sewing machine motor; less than 200W and operating at relatively low speed.I hope someone knows of examples of this type of control because Google won't even tell me about the one in SCM.

author: Skimask
author_rank: Super Contributor
timestamp: May 27, 2015, 11:36:01 pm
content: Use an SSR.

author: moffy
author_rank: Super Contributor
timestamp: May 28, 2015, 01:12:58 am
content: You would need a current shunt to act as a current monitor, to limit/control the current. You would definitely need to fuse it. It's not normally used in a linear fashion but as an AC switch, because the MOSFET has a somewhat sharp turn on point, unless you use feedback to control the current.

author: Kirigozo
author_rank: Contributor
timestamp: May 30, 2015, 02:59:14 am
content: I've been messing with lt-spice and it supports my line of thought. Rough and all as it is I think the project is worth pursuing.What I was looking for was an absence of fast transitions that would produce lots of EMI and everything looks smooth. Ramping the gate voltage in sync with the mains might be interesting but probably unnecessary.Anyway, screen shot attached.
Linear supply you can chain to get +/-12V with only positive regulators ? - Page 1
Forum section: electronics / projects

author: tnt
author_rank: Regular Contributor
timestamp: April 19, 2013, 01:06:20 pm
content: Imagine I want to do two independent linear supply providing +12V each. They're both using let's say 7812 and using different secondary winding (and so they're floaint wrt to each other).Can I just connect the GND of one to the output of the other to have -12V 0 +12V ?What's the impact / difference to using a 7812 and a 7912 for eg ?

author: IanB
author_rank: Super Contributor
timestamp: April 19, 2013, 02:32:27 pm
content: As long as each supply is independent and isolated you can use a 7812 for both and connect them in series and it will work fine.

author: penfold
author_rank: Frequent Contributor
timestamp: April 19, 2013, 03:48:05 pm
content: The case you speak of is a prime candidate for using a 78xx series regulator and connecting just as you say to get dual rail supply.If the 0V lines are common at the transformer then you need a regulator with its pass element in series with the -ve supply rail (else you're end up messing up the opposing rail) hence the 79xx series
Linear Technology & Mouser - Page 1
Forum section: electronics / projects

author: dc101
author_rank: Regular Contributor
timestamp: March 10, 2014, 02:59:34 am
content: Did I miss something in the news? What's up with Mouser not selling anything made by Linear Technologies? I was looking to build one of those cool pulse generators everyone has been making lately and I found everything EXCEPT the lt1073 on Mouser's website. Turns out Linear Technology isn't even on their line card. Was there a falling out or something? Just seems kind of strange to not sell products from such a large company.

author: true
author_rank: Frequent Contributor
timestamp: March 10, 2014, 03:03:41 am
content: They haven't been selling LT for a while, if ever. A shame because I usually buy all of my stuff there and there are a few LT products I wanted to work with. If I want to use Linear parts I now need a second shipment...Complain at Mouser - if enough people do, maybe they'll meet with LT and come up with a distributor agreement.

author: georges80
author_rank: Frequent Contributor
timestamp: March 10, 2014, 03:24:10 am
content: Digikey is where I purchase LT stuff.You can quite easily get samples direct from LT via the online sample request (just create an account), especially if you have a work email etc. I don't remember Mouser ever distributing LT stuff, which is fine, since Digikey is typically my go to distributor (though I do order from both).cheers,george.

author: calexanian
author_rank: Super Contributor
timestamp: March 10, 2014, 04:00:52 am
content: Yeah. Gotta go to Digikey for LT. Actually in just looking there cause we are using Linear boosters on two of our new designs, I now see they are carrying Sanken! I have been waiting for a major here in the states to be carrying them for years. 4 Star has been the only one for a long time. Sanken are the SHIT!!! for AB audio output devices. Better dare I say, than toshiba. High gains, less gain dropoff, better thermal characteristics, and higher transition frequencies.