hybridfree/eevblog-posts huggingface dataset:
Looking to find the perfect series resonance of my Electronics Lab - Page 1
Forum section: electronics / beginners

author: Zenrei
author_rank: Contributor
timestamp: October 17, 2017, 09:52:45 pm
content: "So, im in the process of developing my own electronic lab" ... so? Every other newbtron in this place is doing the saaame thang."..for that reason im seeking to find equipment that is not too expensive,yet useful for a long depreciation cycle across a broad range of applications" ...big words huh. what are you talking bout willis?"I don't want to be in the predicament of purchasing extremely entrylevel equipment that i outgrow too fast." ... POST THE CODE!!!"ATM im working with some basic electronics,but i have a list of projects that cross the thresholdbetween electronics mechanics, robotics, and materials" ... ooOo Mr Iron Man...you go Gurl!"I've already purchased a Rigol 1054Z but i'm afraidi'll outgrow it too fast" ... You haz said this already."I could spend countless hours going through data sheets,and still not be able to spot the little hiccups as towhy they are not a good purchase" ... Welcome to the real world fur-less cat!"I dont want to be cheap, but i dont need extremetop of the line, and buying on a budget would be nice" ... we are still waiting for your question..."Wow, you are extremely mean" ...you do know I'm just a voice in your head that manages your insecurities... right?"......" ..."I'm Looking to Prototype circuits,devices, and products, both small and large and I'm lookingto invest in equipment that i wont need to upgrade for adecent amount of time" ..."* Work Bench power supply and transformers ...* Long term Oscilloscope* Spectrum analyzer* Spot welder* Grinders* CNC or Design of one* Miller* Band Saw* Band sander* 2-10 foot FDM Printer or Design of one* Miscellaneous* ...... what ARE you building? O.o"... you know" ...... yea i do

author: Vtile
author_rank: Super Contributor
timestamp: October 18, 2017, 12:07:14 am
content: ^^ That is so hard to read.Quote from: Zenrei on October 17, 2017, 09:52:45 pmSo this is what you are after or asking advice to what kind of things to look at on those?There is at least like $10k worth of machinery if the quality level is even near of "professional".Spectrum analyzer alone can be $10k so can be the milling machine.

author: Zenrei
author_rank: Contributor
timestamp: October 18, 2017, 12:24:59 am
content: Quote from: Vtile on October 18, 2017, 12:07:14 amtrue. not looking for perfection, looking for functional and not terribly limiting long term
Looking to get 1 or 2 pcb's etched and I need a manufacturer - Page 1
Forum section: electronics / beginners

author: bgsteiner
author_rank: Contributor
timestamp: February 01, 2014, 03:05:36 am
content: So I'm helping a friend with a project and he needs a couple boards etched for his power supply. I was wondering if anyone here had any recommendation for a service that will do just one or two boards not a batch job of 100.

author: Rerouter
author_rank: Super Contributor
timestamp: February 01, 2014, 03:09:10 am
content: itead or seed studio, cheap for 10 boards under specific sizes (e.g. 5x5 or 10x10mm)

author: zapta
author_rank: Super Contributor
timestamp: February 01, 2014, 04:56:28 am
content: Quote from: Rerouter on February 01, 2014, 03:09:10 amWhat country?In the US,http://oshpark.com/is a good choice.

author: Prime73
author_rank: Regular Contributor
timestamp: February 01, 2014, 05:12:18 am
content: seeedstudio or oshpark in Canada both are good choices

author: imjosh
author_rank: Contributor
timestamp: February 01, 2014, 05:21:00 am
content: Oshpark is good. Elecrow.com is good. Oshpark is in the US so you can get your boards back faster without having to pay a lot for shipping. They cost a bit more than the Chinese places but their boards are probably a bit better quality. If your board is very small, Oshpark can actually be really cheap for three boards.
Looking to identify an older part - Page 1
Forum section: electronics / beginners

author: Johnny10
author_rank: Frequent Contributor
timestamp: June 23, 2017, 08:55:22 pm
content: A friend sent me pics of this device and wondered what it was used for?

author: matkar
author_rank: Regular Contributor
timestamp: June 23, 2017, 09:11:27 pm
content: AC current sensor?

author: Gyro
author_rank: Super Contributor
timestamp: June 23, 2017, 09:22:55 pm
content: Yes, it's a current transformer. The current carrying conductor (primary) goes though the hole in the middle. The secondary is what you see wound at the top.

author: eblc1388
author_rank: Frequent Contributor
timestamp: June 25, 2017, 07:35:10 am
content: Important thing to remember for current transformer:Do not allow the secondary to go open circuit when there is current flowing in the primary side(the conductor that goes through the middle). Very high voltage will be induced that would breakdown the insulation of the winding if there is no load on the secondary or the connection is opened.

author: Johnny10
author_rank: Frequent Contributor
timestamp: June 25, 2017, 03:14:31 pm
content: What vintage is this device?1940's

author: SeanB
author_rank: Super Contributor
timestamp: June 25, 2017, 04:34:41 pm
content: From the fasteners and the overall layout probably from the 1960 to 1990 period, those were very common in metering applications, typically having a 5A secondary current and a 50-500A primary current rating.Simple way to find the rating is to use a 12VAC downlighter transformer ( a real transformer, not an electronic one but the heavy lump of copper and iron ones) and a 50W 12V lamp, and put 5a through a wire through the middle of the core, with a DMM set to AC amps ( 10A range) measuring the secondary current. Then you can simply calculate the turns ratio for this unit.I currently use one in reverse, to drive a kWh meter so I get a better resolution, using it as a 1:10 current transformer to drive the 60A current coil in the meter. 972.6 kWh since I put it in use.
Looking to measure femtoampere using uCurrent  - Page 1
Forum section: electronics / beginners

author: Aneikei
author_rank: Newbie
timestamp: October 18, 2017, 07:22:28 am
content: Hi all. I'm looking to measure femtoamps(1 femtoamp = .001 picoamps). I believe the uCurrent can measure picoampers. However if daisy chaining two uCurrent's together would that in theory allow me the sensitivity to measure femtoamps? And if possible would there be too much noise?Thank you for you insight and time.

author: tszaboo
author_rank: Super Contributor
timestamp: October 18, 2017, 10:10:02 am
content: Smallest range is 1mV/nA, so you have 1nV/fA output. And the MAX4239 on it has typical 1000 fA input bias. So maybe you should use a tool which is not designed to do one million times bigger things.You wouldnt measure micrometers with this, would you?

author: EEVblog
author_rank: Unknown
timestamp: October 18, 2017, 10:14:08 am
content: You need this:and you need to read this:http://www.tek.com/sites/tek.com/files/media/document/resources/LowLevelHandbook_7Ed.pdfYou can't just casually measure femptoamps.

author: Gyro
author_rank: Super Contributor
timestamp: October 18, 2017, 10:32:11 am
content: You could try this thread too:https://www.eevblog.com/forum/projects/picoammeter-design/

author: Aneikei
author_rank: Newbie
timestamp: October 18, 2017, 06:52:07 pm
content: Thank you much for the head start gentlemen. It's much appreciated. This is fantastic stuff!

author: David Hess
author_rank: Super Contributor
timestamp: October 18, 2017, 07:01:21 pm
content: The example shown in that discussion threadherecan get close. I used a similar circuit with an LMC6081 graded for low input current for better precision than the LMC662 but you can also buy the pre-graded LMC6001. Offhand I do not know of any better parts.Construction is critical. For a one off, I would air wire the input side over a ground plane. When we did this on a printed circuit board, the input side was air wired with the non-inverting input pin of the DIP package bent to be horizontal to the printed circuit board.Noise will limit precision. One way to get around this is to replace the high value transimpedance gain resistor with a capacitor to make an integrator and then make measurements over time. Use a low capacitance relay to reset the integrator. Robert Pease wrote a couple articles discussing this implementation:http://www.electronicdesign.com/test-amp-measurement/whats-all-femtoampere-stuff-anyhowhttps://www.ti.com/ww/en/bobpease/assets/www-national-com_rap.pdf
Looks like a ceramic cap but - Page 1
Forum section: electronics / beginners

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: March 21, 2023, 12:11:48 am
content: Looks like a typical ceramic cap.Sez: 102 SUM (these are the only markings, nice and clear)But goes down from 1nF to .5 nF with a little hot air.And goes down a little if I touch it with warm fingers, Then recovers slowlyWhat is it??

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 21, 2023, 12:20:00 am
content: Doesn't surprise me.Y5V capacitorscould almost double as temperature sensors.

author: langwadt
author_rank: Super Contributor
timestamp: March 21, 2023, 12:27:02 am
content: https://global.discourse-cdn.com/digikey/original/2X/6/6f8e564933b52a46b7ff6c163e039d3ac01290f2.jpg

author: james_s
author_rank: Super Contributor
timestamp: March 21, 2023, 12:33:59 am
content: Quote from: Kim Christensen on March 21, 2023, 12:20:00 amMight be fun to make a thermometer that uses one as the sensor. Seems like something Heathkit would have done back in the day. They used diodes as sensors in some of their weather stations.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: March 21, 2023, 12:35:24 am
content: Thanks for the replies, Looks like it is a 5YVNot a SMD, just a ceramic looking cap with two substantial leads.Yea I guess someone could consider using it as a temp sensor.Thanks again

author: langwadt
author_rank: Super Contributor
timestamp: March 21, 2023, 12:37:18 am
content: Quote from: Kim Christensen on March 21, 2023, 12:20:00 amthermometer, varicap, and microphone all in one

author: srb1954
author_rank: Super Contributor
timestamp: March 21, 2023, 04:33:08 am
content: Quote from: langwadt on March 21, 2023, 12:37:18 amAnd clock and calendar too, if you factor in the capacitance drift through aging.

author: Infraviolet
author_rank: Super Contributor
timestamp: March 21, 2023, 08:39:43 pm
content: Quite possibly a polyfuse. A polymer type of fuse which self resets after an over-current event. Resistance climbs sharply when it gets too hot, cutting off the current that is generating the heat, then once it is cool it can take full current again. If it only takes some mildly warm air to change the resistance (have you measured that as well as capacitance) then it must be a polyfuse set for protecting against even pretty small over-currents, a few hundred mA or even less perhaps.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: March 21, 2023, 10:15:08 pm
content: Not a polyfuse any DC resistance measurement is an open.

author: wraper
author_rank: Unknown
timestamp: March 21, 2023, 10:21:28 pm
content: Half of capacitance when hot is not that bad actually. Some drop almost this much with just heat from the fingers when holding them.

author: james_s
author_rank: Super Contributor
timestamp: March 22, 2023, 01:22:43 am
content: This trait and the fact that most MLCCs lose a substantial portion of their capacitance if there is a DC voltage across them is not nearly as widespread knowledge as it ought to be. This can and will bite you if you don't take it into account.
LoRA range question - Page 1
Forum section: electronics / beginners

author: AndrewM
author_rank: Contributor
timestamp: October 10, 2019, 05:54:34 pm
content: So, supposedely LoRA has 10km line of sight range?In theory, (ignoring airspace and radio regulations for now), if I had a LoRA device on a weather balloon, it would be able to talk to the ground until it hit ~10km altitude?I'm not actually planning to do anything of the sort, I was thinking more along the lines of a LoRA relay stuck on an RC plane that could circle over an area and get line of sight to a bunch of LoRA devices on the ground that otherwise wouldn't have LoS due to hills, mountains, trees, etc...

author: sokoloff
author_rank: Super Contributor
timestamp: October 10, 2019, 06:11:48 pm
content: Each doubling of distance in free air costs you -6dB in link budget. The distances possible in free air are wildly longer than 10km.https://www.thethingsnetwork.org/article/ground-breaking-world-record-lorawan-packet-received-at-702-km-436-miles-distance

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: October 10, 2019, 06:23:25 pm
content: I have tested this Reyax rylr 896 Lora module SX1276 up to 8.80 km

author: floobydust
author_rank: Super Contributor
timestamp: October 10, 2019, 08:23:06 pm
content: I can't find what antenna the air balloon used. Antenna gain and directivity are important.

author: Whales
author_rank: Super Contributor
timestamp: October 10, 2019, 11:35:24 pm
content: Also: if you are using only a single balloon then it may be possible for your ground station to have a directional antenna. That's assuming you are running your own station and not using a public network one.
Lorton cap ck w/Siglent 1052, pictures and video - Page 1
Forum section: electronics / beginners

author: billbyrd1945
author_rank: Regular Contributor
timestamp: November 28, 2018, 10:49:58 pm
content: Wanted to see if my super cheap signal generator and my Siglent SDS1052DL+ would suffice to do the o'scope cap check featured in this video:I was able to get a nice waveform but couldn't get the math to work out. I have no problem whatsoever in accepting that I simply can't deal with that many zeros and conversions. If you'd like to try, here's the setup I used if you'd like to give it a try: Hertz jumper: max; all knobs centered; resistor: 22k; cap: 4.7uF. Images attached.
Losing power off of a led - Page 1
Forum section: electronics / beginners

author: Ryanlg
author_rank: Newbie
timestamp: January 27, 2012, 02:20:11 am
content: Hi guys,This may seem like a pretty easy question. I have a project I have been working on, and I wanted to add a fancy switch and led to it. The main circuit of it requires 12v and I have 8 AA batteries in it. When adding a led I chose a red 12v flashing led from Jaycar. When I soldered it in in series, I was only getting 6v to my main circuit, instead of 12v. So I thought " stupid me it needs to be in parallel."so I soldered the led in parallel, but when the switch is turned off, the flashing led flashes.Any suggestions guys how to get 12v to the main circuit with the led working properly.

author: joelby
author_rank: Frequent Contributor
timestamp: January 27, 2012, 02:30:44 am
content: Try putting the LED in parallel with the circuit, but on the circuit side of the switch, not the battery side. If it's still flashing when the battery is not in the circuit, you must have some other voltage source present.

author: amspire
author_rank: Super Contributor
timestamp: January 27, 2012, 02:32:27 am
content: Both the ways you connected the LED were wrong. The LED has to be in parallel with the other battery load. So one side of the LED connects to to the load side of the switch. The other side of the LED connects to the side of the side of the battery not going to the switch.

author: sonicj
author_rank: Frequent Contributor
timestamp: January 27, 2012, 05:32:10 am
content: here ya go

author: Ryanlg
author_rank: Newbie
timestamp: January 27, 2012, 05:38:09 am
content: Quote from: sonicj on January 27, 2012, 05:32:10 amThank you!

author: w2aew
author_rank: Super Contributor
timestamp: January 27, 2012, 02:46:22 pm
content: ...and don't forget the current limiting resistor in series!

author: sonicj
author_rank: Frequent Contributor
timestamp: January 27, 2012, 07:47:15 pm
content: Quote from: Ryanlg on January 27, 2012, 05:38:09 amno problem!and like w2aew mentioned, the resistor in series is important. 470? should be a good starting point.-sj

author: IanB
author_rank: Super Contributor
timestamp: January 27, 2012, 08:01:48 pm
content: I think if it's a "12 V indicator LED" then the resistor will probably be built in.
Lost in a world of connectors - Page 1
Forum section: electronics / beginners

author: StarFishPrime
author_rank: Contributor
timestamp: February 19, 2015, 10:16:01 am
content: Hicould anyone help here.I'm building a series of earth-science sensors in schools- magnetometers, infra-sound, seismometer etc and am looking at suitable connectors between the signal cables and metal pcb enclosures.. Taking the magnetometer the sensor outputs a ~100kHz square wave fed indoor via a 20m shielded 3 core cable (the other lines being +5V and grd). Is there any merits to using metal circular miniature DIN vs the 9 pin DB9 connectors popular on computers.As I am working on a series of different sensors, all required shielded lines of up to 4 core - low voltage, I wanted to standardise on a neat connector for all the projects (neat impresses management who think these can be knocked out in an hour).Could anyone give me any pointers here?ThanksIan

author: LabSpokane
author_rank: Super Contributor
timestamp: February 19, 2015, 04:00:29 pm
content: The DIN connectors have options to polarize the connectors whereas the affordable DB9 options don't. I don't think either is better than the other for signal integrity at those frequencies. The DIN will also take up much less PCB space.The downside of mini circular DIN is that the plug side is much harder to source than the DB series. Most are intended to be factory over molded.

author: SeanB
author_rank: Super Contributor
timestamp: February 19, 2015, 04:59:36 pm
content: Go for the 9 pin D connector, as that is both common, cheap and easy to wire up. You just standardise the connector for the location of pins like power, ground, and use the shell as the screen ground for the cable. You then can simply assign a pin for each type of signal that will come in, so you can have all the digital pins on a common group, and all analogue with a specified level on a certain pin group. As well it is simple to key the sockets by cutting a pin off and using a filled socket as a keyway.

author: StarFishPrime
author_rank: Contributor
timestamp: February 21, 2015, 11:05:56 am
content: Thanks for the replies - excellent advice.CheersIan
Lost in the ESD-mat forest. - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: February 03, 2019, 09:22:07 pm
content: Happy was I walking into DigiKey.com, "give me a ESD mat please"Digikey:layers (1,2,3)materiale (rubber, foam rubber, laminated, elastomer, polymer)features (Dissipative, conductive, antistatic, anti fatigue)?Me: Ehm what, Ehm who where?Can you please try to help me answering these questions?My table is a 1x2 meter slap of wood.

author: jpb
author_rank: Super Contributor
timestamp: February 03, 2019, 09:55:40 pm
content: The best mats are rubber but these are more expensive.For a bench you probably want a dissipative layer on top (so you dissipate charge without shorting out any circuit board laid on top) with a conductive layer underneath (to give a good grounding).The anti fatigue only applies to floor mats (i.e. they are soft to stand on if you're working on your feet all day and don't want to stand on a hard floor like concrete).You can either cover your whole bench which is expensive and probably requires you to buy a roll and cut it to size or you can do what I did and just get a mat that covers your working area.The other important thing is that they are heat resistant (for soldering).The one I went for was this:https://www.digikey.co.uk/product-detail/en/desco/66045/16-1074-ND/405847EDIT: to explain the terms:dissipative - very high resistance, almost an insulator but with enough conductance that a bit of static (small charge/high Voltage) will dissipate to ground but at a slow enough rate that there is no danger to circuits (ESD needs to be allowed to flow away but not be suddenly conducted to ground as you'd have with say a metal table top).conductive - relatively low resistance (though probably more resistive than a metal) which provides a reasonable path to ground for charge getting through the thin dissipative layer. The whole mat should be connected to ground via a 1Mohm resistor anyway so the typical resistance to ground is of the order of tens of megaohms or more.

author: FriedMule
author_rank: Frequent Contributor
timestamp: February 03, 2019, 10:37:49 pm
content: Thanks a lot, great link.Was wondering if anyone has a, something like 7x4 feet / 210x110 cm cutoff some ware I could buy?
Lost on SEPIC parameters - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: March 03, 2022, 07:38:12 pm
content: I'm having trouble with choosing the parameters of a SEPIC circuit using theLT3579 IC, specifically the inductor. I designed it around certain inputs and outputs, plugging the formulas into Excel, and seeing the parameters that come out. I've attached my worksheet below as a reference, so I was wondering if mychoice of an inductoris okay given the calculations.Following the formulas, I pick my input/output voltages and the frequency to start. Then, it's just plugging things in. I'm just lost at picking the right inductor. I'm given a range of values for the inductor, and this range is dependent on the switching frequency. The higher the frequency, the smaller the range. Picking the larger inductor in the range would result in a smaller ripple current. However, you're also limited by the selection of coupled inductors available. For instance, in my calculations at 1.2 MHz, I have a range of 1.45-13.5 uH (with a typical value of 3.77 uH). Selecting one at 10 uH (as seen in mylinkabove), the ripple current reduces to 0.68 amps (which still seems pretty high to me). My inductor pick fits the criteria, and its current rating is high enough for the peak current. Given my design methodology and parameters, does this seem like a good choice?As a related question, what can I do to further reduce the ripple current? Furthermore, while the peak current is a little high, would a soft-start capacitor help mitigate that value? By allowing the IC to start up "slowly", the inductor shouldn't reach peak current at startup?
LOTO USB Oscilloscope practice(2): Diode --- Bridge Full Wave Rectification - Page 1
Forum section: electronics / beginners

author: jiangtao.lv
author_rank: Regular Contributor
timestamp: May 13, 2020, 10:36:04 am
content: Resources used in the experiment:4 rectifier diodes, 500R resistance (for load), oscilloscope, signal source.Note: The resistance value does not need to be accurate. This resistance is used as a load. The resistance value should not be too large. If it is too large, the current will be limited to a small value, which may cause the rectifier diode to cut off. Pay attention to the polarity when soldering the diode. The signal source should be able to generate a sinusoidal AC signal with a frequency of 50HZ above plus or minus 2V.Here is the video:https://youtu.be/eI2Kz5zfHQgThe video uses the OSC482S's own signal source module to generate a positive and negative 2V sine wave as the input of the diode bridge circuit. The two end channels of the oscilloscope are used to detect the terminal voltage of the output terminal respectively, and the channel subtraction shows the rectified waveforms added across the load. In order to see the rectification result clearly, we did not add a filter capacitor in the video. Once the capacitor is added, the output will become DC. You can try it yourself.

author: BravoV
author_rank: Super Contributor
timestamp: May 13, 2020, 10:41:56 am
content: Are you aware that many, or I believe majority of the forum members here are not familiar with Chinese language ?

author: jiangtao.lv
author_rank: Regular Contributor
timestamp: May 13, 2020, 02:15:14 pm
content: Yes,you are right。I found the youtobe could translate the subtitles into your native language conveniently,so I added subtitiles for it.
Loudspeaker impedance - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 25, 2014, 05:54:56 pm
content: HiWe're going to build a retro radio and the design calls for an LT700 transformer (secondary is 3.2 ohms) and a three ohm speaker. However, every small speaker on eBay is at least eight ohms. Would one of those be ok ?Thanks

author: SeanB
author_rank: Super Contributor
timestamp: July 25, 2014, 06:00:03 pm
content: It will work, and will be slightly softer but works well.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 25, 2014, 06:02:43 pm
content: Thanks for the quick reply. Any value in adding a resister in parallel to get it nearer three ohms ?

author: SeanB
author_rank: Super Contributor
timestamp: July 25, 2014, 06:14:26 pm
content: No real value, it will work with any speaker from 2R to 16R with no problems. The speaker impedance is in any case going to vary with frequency as well.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 25, 2014, 06:19:28 pm
content: Thanks Sean. Ordered.

author: IanB
author_rank: Super Contributor
timestamp: July 25, 2014, 06:49:04 pm
content: Maybe too late now, but 4 ohm speakers might be found from some sources (perhaps intended for car audio use?)
Low cost 12V relay/30A - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: December 22, 2014, 08:37:42 am
content: 1. I need low cost 5 pin, 12V relay with SPDT & in both NC & NO state current should be 30A or higher.2. Any suggestions?3. I have searched this relay, but it is costly, any cheaper part?:http://www.parts-express.com/12-vdc-automotive-5-pin-relay-spdt-30-40a-bosch-type--330-073

author: Jeroen3
author_rank: Super Contributor
timestamp: December 22, 2014, 09:21:35 am
content: Do you have DC or AC to switch?Relays might say they can handle DC 30 Amps, but they might not be able to switch 30 Amps DC that many times. DC has a high change of welding the contacts together because there will always be current, also when the contact resistance is at its highest point in the switching action.

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: December 22, 2014, 10:07:41 am
content: To Add End application: Will be switching main on or off depending upon some condition.Input driving : 12V dcOutput control : 220V ac , 30A ac , 50Hz

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: December 22, 2014, 10:20:06 am
content: That's an automotive relay don't use it for 230VAC application. use properly rated relay, i would use those motor relay for 30A ... am sure you not find a proper relay under 2$

author: Zero999
author_rank: Super Contributor
timestamp: December 22, 2014, 10:52:44 am
content: Quote from: hamdi.tn on December 22, 2014, 10:20:06 amI agree. This reasonable price for an automotive relay designed to switch only 12V. A mains relay with this current rating will be far more and if you find one cheaper, then it's a fake so don't buy it.

author: Jeroen3
author_rank: Super Contributor
timestamp: December 22, 2014, 11:55:44 am
content: For those kind of relays, to switch off your entire house just after the main fuse, you'll be looking at $50 to $500 relays. Actually, contactor is a more common term for these.Such as these:http://nl.rs-online.com/web/p/contactors/7434918/What plug is on your device? If you running 6 kW through 1 phase you'll be having some heavy wiring.6mm squared and above, depending on fusing.
Low cost 12V/6A dc-dc for lead acid - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: October 10, 2016, 03:30:11 am
content: 1. I have a lead acid battery in my board. It needs three outputs: 12V/3A, 12V/3A , 5V/2A. For first two outputs, I will keep single 12V/6A2. For 5V/2A I will use LM2576 in front of lead acid battery.3. Since lead acid battery varies from 10.5V to 14V. For getting 12V/6A output. I need some cheap & low component board for it. Efficieny is not as issue here for me. Not want that should be 90% or higher.Only thing is low cost, like LM2576, only few external components are required.System should also have a low voltage cut off at 10.5V, otherwise it will drain the entire battery.4. I had serached for many system. They are all very expensive & also TI webbench also suggest costly systems.

author: oldway
author_rank: Super Contributor
timestamp: October 10, 2016, 05:06:37 am
content: For the 12V outputs, the easiest solution is to use the battery voltage directly from 12V to 10.5V.This can be done because battery voltage vary very little during the battery descharge.For voltages higher than 12V (during recharge), use the diode drop principle with relays.With three diodes in serie, you will have 1.8V drop and consumer voltage will be 12.2V for 14V battery voltage.Use 3 relays to short circuit the diodes to maintain 12V for the consumer.

author: rx8pilot
author_rank: Super Contributor
timestamp: October 10, 2016, 05:49:47 am
content: How tight of regulation do you need? What types of loads? How low cost is low cost? Are you building one for yourself, or making a product of some sort?Sent from my horrible mobile....

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: October 11, 2016, 10:11:16 am
content: Regulation for buck-boost if it can match LM2576 performance.Making a product.

author: rx8pilot
author_rank: Super Contributor
timestamp: October 11, 2016, 07:00:14 pm
content: Quote from: Vindhyachal.takniki on October 11, 2016, 10:11:16 amIf that is all the information you can offer, I am not sure what I should bother saying. The amount of effort you into this is directly proportional the the help you should expect.
Low cost buck-boost (inverting) switching regulator? - Page 1
Forum section: electronics / beginners

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: March 19, 2024, 06:50:41 pm
content: I'm looking for a low-cost buck-boost (inverting) switching regulator with BOTH adjustable constant-voltage (CV) and constant-current (CC) control. It needs to work down to 4v (input voltage of ~5v) with a maximum current support of 3A.I'm thinking of going with this (https://www.aliexpress.com/item/1005006615276476.html) or this (https://www.aliexpress.com/item/1005004702899732.html) product from AliExpress, but I'm wondering if anyone has any suggestions on cheaper products? Or maybe a schematic for a DIY version that I can make? Thanks.

author: kevin.gibbs
author_rank: Regular Contributor
timestamp: March 26, 2024, 03:25:20 pm
content: It seems you can't find anything cheaper than on Aliexpress. The first link seems suitable. The second one's description says a minimum voltage difference of 2V. It seems to be only a step-down module.
low cost LCR meter will be fine for me ? - Page 1
Forum section: electronics / beginners

author: ammjy
author_rank: Regular Contributor
timestamp: December 01, 2019, 09:14:26 am
content: Hello, EEVblog Users !Thanks you for watch this question, I appreciate.My target of measurement is RC level BLDC motor.and RC level BLDC has very simple 3 phase circuit that can be expressed with inductors.please see the attached photo.the values that other person have measured other same RC BLDC motor has internal resistance and internal inductance each 14.05 Ohm and 0.102 H from inputs U-V or U-W.my BLDC motor also almost same RC BLDC model so I guess result value will be similar.But, If I do measure values with low cost product such as UT603 Uni-T, values will be fine and will has reliability ?I would like to ask your advice. Please let me know.I never have used LCR meter befote. so I don't have any clue about it.

author: ebclr
author_rank: Super Contributor
timestamp: December 01, 2019, 05:28:03 pm
content: One very cheap device may help you outhttps://pt.aliexpress.com/item/32814240028.html?spm=a2g0o.productlist.0.0.43a038501PP96J&s=p&algo_pvid=7692934c-e115-45a2-8e1f-d0038ea91d9b&algo_expid=7692934c-e115-45a2-8e1f-d0038ea91d9b-8&btsid=0321a6a2-19d3-46b1-85ee-fb479c74183f&ws_ab_test=searchweb0_0,searchweb201602_9,searchweb201603_53

author: mcovington
author_rank: Regular Contributor
timestamp: December 01, 2019, 08:22:52 pm
content: Here's that page, in English:https://www.aliexpress.com/item/32814240028.html

author: t1d
author_rank: Super Contributor
timestamp: December 01, 2019, 10:17:26 pm
content: Quote from: mcovington on December 01, 2019, 08:22:52 pmI have this unit and I love it. I made a small set of wires, to be able to take readings, when I can not put the Device Under Test (DUT) into the ZIF socket that is on the T4.You need a section of header pins having three pins. They will be placed into socket numbers 1, 2, and 3, of the ZIF socket. These are the socket numbers that the meter reads. #1 and all other sockets, except #2 and #3, are ground. Notice the numbers on the PCB. And, each socket is in parallel to the socket just across the divider.Solder a length of small wire to each pin. Add your choice of connectors to the free end of the wires... I used individual header pins to make probes, but alligator clips would be nice, too.Please remember that the new probe wires will effect your readings. This should be taken into account, if precision is needed. I generally only use the leads to make pass/fail tests on questionable components.

author: Wimberleytech
author_rank: Super Contributor
timestamp: December 02, 2019, 12:42:29 am
content: QuoteSame here. Quick and easy. Accurate enough for all my needs.
Low cost mosfet replacement for diode in boost application - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: September 05, 2020, 05:22:47 am
content: 1. have a boost circuit where:a) Vin: 8.1V to 12.3Vb) Vout = 12.3V/12.5Amps (If 12V/12.5A possible then better, but my ckt gives 12.3V, otherwise need to switch to sepic, which is costly and 12.3V is acceptable so took this low cost part)2. Here is circuit which I will use. Want to replace D2 diode with mosfet since at 12.5Amps even a Schottky will produce lots of heat.3. I searched for replacement of diode with p channel mosfet like here:https://electronics.stackexchange.com/questions/223935/understanding-an-ideal-diode-made-from-a-p-channel-mosfet-and-pnp-transistors4. Also looked for N-channel mosfet replacement, found some high side driver like these:https://www.microchip.com/paramchartsearch/chart.aspx?branchID=901025. But one doubt is mosfet are bidirectional paths, while diode is single side. So will it create issue in circuit?6. Any other better way to replace with diode here. Need to change in this circuit only. I know there are sync boost converters also, with mosfets, but expenive or if some low cost alternative available?

author: Siwastaja
author_rank: Super Contributor
timestamp: September 05, 2020, 06:30:21 am
content: You need a thing called "synchronous boost".It's quite iffy to replace the diode only; you would need averyfast replacement circuit. Instead, normally you do this by picking a different DC/DC controller IC, one which is designed for synchronous boost. It will offer a gate drive signal for your synchronous FET directly!TLDR: Replace IC1 with a synchronous boost controller which drives two FETs.Another comment: Get rid of the discrete gate driver Q1/Q5, and just use a driver IC which can drive enough current to your MOSFET(s). At this power level, you shouldn't have problems finding complete integrated controller IC which has enough gate drive oomph so that no external gate driver (IC or discrete) is needed.

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: September 06, 2020, 02:33:31 pm
content: I think synchronous boost would be better choice.
Low current high voltage current measurement - Page 1
Forum section: electronics / beginners

author: tmf
author_rank: Contributor
timestamp: June 01, 2015, 04:23:38 pm
content: I have search and search for this information online and can not find.I have made a zapper type ciruit, 2KV output probably a few millamps. I want to measure the "zap" current. How to isolate and what will be needed for a uC to get this information?Also want to do it on the cheap.Richard.

author: rolycat
author_rank: Super Contributor
timestamp: June 02, 2015, 02:23:26 am
content: There are lots of "zapper type circuits" - it would be useful if you provided a little more information:Do you have a circuit diagram you can share?Why do you want to measure the current with a computer?How cheap is cheap, and what equipment do you have?What are you zapping - mosquitos, sparks, people?

author: tmf
author_rank: Contributor
timestamp: June 02, 2015, 04:02:46 am
content: Mainly bugs, would just like to know the intensity, maybe just detect the length of zap and not current, it may be the same current all the time.... not sure what to expect. See image attached.

author: rolycat
author_rank: Super Contributor
timestamp: June 02, 2015, 10:27:06 am
content: A current transformer hooked to a fast ADC would be a good starting point and would give you a voltage proportional to the current together with isolation. You should also be able to measure the discharge duration. Because you have a high voltage and low current you might have to wind your own.

author: tmf
author_rank: Contributor
timestamp: June 02, 2015, 12:54:49 pm
content: Quote from: rolycat on June 02, 2015, 10:27:06 amWould the extra resistance from the windings kill the zap or at least attenuate it? Need to look up current transformers and see how they work.Thanks!Richard.

author: HighVoltage
author_rank: Super Contributor
timestamp: June 02, 2015, 01:45:23 pm
content: Cheap way: Series Resistor against ground and measure the voltage dropReal way: Current transformer with BNC connector directly to the scope

author: G7PSK
author_rank: Super Contributor
timestamp: June 02, 2015, 02:54:13 pm
content: As the thing makes a spark just looping the earth lead to the probe point may well pick up any RF and from that you can work out the spark duration.
Low Current LED - Page 1
Forum section: electronics / beginners

author: modernjack3
author_rank: Contributor
timestamp: January 21, 2016, 07:34:17 am
content: Hello guys !I am currently trying to build a LED Clock but I have troubles finding LEDs tht dont suck too much power since there will be about 150 of them and they all will be parallel ... Colors Needed are Blue, Red , Yellow... Thanks for your help ! - The clock will be used indoors but should also be visible on a sunny day when sun falls through the window..

author: Simon
author_rank: Unknown
timestamp: January 21, 2016, 07:45:59 am
content: LED's will take as much power as you allow them to. LED current is regulated with a series resistor or a current source driver for larger power ones. The ap rating of an LED is simply the maximum it can tolerate not what it will use.

author: Falcon69
author_rank: Super Contributor
timestamp: January 21, 2016, 07:56:02 am
content: LED's are just like gold fish. Keep feeding them food, sooner or later, they are going to explode.Simon is right.You can run the LEDs like in a matrix array to run a clock. It's pretty easy to do using transistors/mosfets and an arduino or other method. There's instructions all over the net on how to do this.Just google 'LED Matrix Clock'

author: Zero999
author_rank: Super Contributor
timestamp: January 21, 2016, 11:42:04 am
content: Red and blue LEDs are very efficient and hardly need any current to make them light. Due to the response of the human eye, in bright conditions, red is the most efficient but when it's dark, it's overtaken by blue.The problem is yellow LEDs aren't very efficient and need a comparatively high current to achieve the same brightness as red and blue LEDs. It's more efficient to use a blue LED with a phosphor or mix light from red and green LEDs to make yellow light.

author: modernjack3
author_rank: Contributor
timestamp: January 21, 2016, 03:33:03 pm
content: Hey guys !Thx for the replies but what i really wanted to know was if there were any LEDs tht dont need a lot of current to be bright enough for daylight..they will sit behind milky plexy glass

author: Kleinstein
author_rank: Super Contributor
timestamp: January 21, 2016, 04:26:27 pm
content: The high efficiency LEDs can produce quite some light from a lowe current (e.g 10 µA range). However they are usually not tested at such low current so not everey LED must work as this are not the garantied conditions, but many do. How much light is needed really depends on the application and background light: in a dark room one can see a good LED at 1 µA or even less. In bright sun it may take 10 mA. So likely you just have to get a few good LEDs and test how much current you need.There are low current LEDs specified at something like 1 mA or 0.1 mA - but the Chips inside are ofte not that much different from medium efficiency LEDs.
Low Dropout Voltage Regulator (LDO) Design - Page 1
Forum section: electronics / beginners

author: JYuan
author_rank: Newbie
timestamp: December 01, 2017, 05:14:31 pm
content: Hello,Can anyone suggest the possible value of current source, Vref, VDD, R1, R2, Cload and Rload to me.Because I trying to run a simulation on cadence software based on LDO design.Techonology is 0.18um.Thanks.
Low frequency, <1% duty cycle, IC oscillator - Page 1
Forum section: electronics / beginners

author: raff5184
author_rank: Regular Contributor
timestamp: April 02, 2021, 01:22:39 pm
content: Hi,Im looking for a low power (few microamps or even nanoamps) chip capable of generating low frequency PWM signals in the range of 50-200Hz but with a very small duty cycle, like 0.2-4%. i found several adjustable oscillators but in the MHz range, which helps with the d.c. but frequency then is a problem. Is there an IC that does this? I'm looking for a chip, if it even exists, not how to make my own circuitThank you

author: Picuino
author_rank: Super Contributor
timestamp: April 02, 2021, 02:02:22 pm
content: Perhaps with the ICM7555.https://www.renesas.com/eu/en/document/dst/icm7555-icm7556-datasheetEDIT:Another option is a small uC in sleep mode controlled by watchdog.

author: raff5184
author_rank: Regular Contributor
timestamp: April 02, 2021, 02:22:22 pm
content: Quote from: blueskull on April 02, 2021, 01:28:38 pmmultiplies of 2 for freq is more than acceptable. What do you mean constant pulse but not constant duty cycle?

author: raff5184
author_rank: Regular Contributor
timestamp: April 02, 2021, 02:24:13 pm
content: Quote from: Picuino on April 02, 2021, 02:02:22 pmI'll take a look thanks. I tried a uC and it does the trick but in my case was absorbing too much. Any uC you'd recommend?

author: Picuino
author_rank: Super Contributor
timestamp: April 02, 2021, 03:09:25 pm
content: The ICM7555 has an static supply current of 40uA @ 5V.I would recommend you a low power PIC microcontroller (XPL).https://www.microchip.com/ParamChartSearch/Chart.aspx?branchID=30048Perhaps this one:https://www.microchip.com/wwwproducts/en/PIC12F1571https://ww1.microchip.com/downloads/en/DeviceDoc/40001723D.pdfeXtreme Low-Power (XLP) Features:Sleep mode: 20 nA @ 1.8V, TypicalWatchdog Timer: 260 nA @ 1.8V, TypicalOperating Current: 30 uA/MHz @ 1.8V, typical

author: Terry Bites
author_rank: Super Contributor
timestamp: April 02, 2021, 03:18:33 pm
content: TPL5110Runs on ant farts.

author: raff5184
author_rank: Regular Contributor
timestamp: April 02, 2021, 03:29:33 pm
content: Quote from: Terry Bites on April 02, 2021, 03:18:33 pm

author: Picuino
author_rank: Super Contributor
timestamp: April 04, 2021, 06:43:36 pm
content: However, if you power a PIC XPL with a small 200mAh button cell, it will take 87 years to use due to the consumption of the watchdog.260nA of the watchdog consuption is 10 times more than the consumption of the TPL5110, but negligible anyway.200mAh / 260nA = 769230h = 32051 days = 87,8 years
Low imp speakers on Panasonic SA-HE100 - Page 1
Forum section: electronics / beginners

author: Larsson55
author_rank: Regular Contributor
timestamp: October 10, 2024, 04:22:31 pm
content: Have this Panasonic AV Control Receiver model SA-HE100, 20+ years old, its part of our home theater system. When I turned the system ON the receiver says "Overload Turn the System OFF" and there is no sound. Checking the users guide it said to check the speakers wiring but found nothing wrong with the wiring or speakers. It also has a tiny message saying "Low imp speakers". Disconnecting all speakers wiring from the receiver that message is still there so I guess its related to the receiver. I also removed the cover and the unit inside is spotless clean despite it was never opened.I'm not into electronics but before I scrap the unit I wonder if there is something simple I can do to save it.Many thanks.

author: edavid
author_rank: Super Contributor
timestamp: October 10, 2024, 04:41:39 pm
content: Quote from: Larsson55 on October 10, 2024, 04:22:31 pmOverload protection faults like this are usually pretty hard to diagnose and repair, and this model has little value.

author: Larsson55
author_rank: Regular Contributor
timestamp: October 10, 2024, 10:48:40 pm
content: Thanks for your time, I understand
Low Impedance Amplifier Suggestions - Page 1
Forum section: electronics / beginners

author: darthhideous
author_rank: Newbie
timestamp: January 09, 2019, 12:47:26 am
content: Hi all,I'm looking for an amplifier capable of driving a 2(preferable) or 4(predominantly resistive with small XL) load with a minimum output power of ~100W. The required bandwidth is 50Hz - 200kHz. I'm not after a perfectly flat response across the band however at least 50W output is required at 200kHz. Operation would not be continuous with an estimated min duty cycle of 1 min on, 3 min off. Does anyone have suggestions for an off the shelf solution or alternatively power op-amps that could do this? I've had a look at the OPA549/OPA541 but they look dicey around 200kHz. I tried two LM3886s in parallel and they worked okay but hit their limit at around 200kHz.Thanks!

author: David Hess
author_rank: Super Contributor
timestamp: January 09, 2019, 01:37:05 am
content: What kind of distortion levels are acceptable?Let's see; 100 watts into 2 ohms is 3.5 amps 7 volts so 7 amps 14 volts peak for sine waves. What you are describing is essentially a super class-AB audio amplifier. If you do not want to go the discrete route, then a part like theApex MP111is more than suitable if driven by a high level signal. Another alternative would be something like several 7-lead TO-220LT1210sin parallel.I would probably try a variation of the first circuit included below using fast D44/D45 output transistors but that is just me. My own old but similar discrete audio amplifier design had a bandwidth above 500kHz using much slower output transistors.
Low Latency Wireless Audio - Need advice - Page 1
Forum section: electronics / beginners

author: neo__04
author_rank: Newbie
timestamp: March 17, 2017, 01:58:17 am
content: Hi all,Working on a little wireless audio project.Its wireless audio for a metal detector. So i need as minimal latency audio as possible.There are commercial products available that utilize 2.4ghz audio, not bluetooth, but 2.4ghz somehow.I've been playing with FM radios, but having a bit of trouble amplifying the signal due to noise etc.Can anyone suggest a better option?Open to suggestions as I'm struggling for ideas.