hybridfree/eevblog-posts huggingface dataset:
Eakins Microscopes - Why are there different style housings for a sensor? - Page 1
Forum section: electronics / beginners

author: Aston01
author_rank: Newbie
timestamp: December 24, 2024, 11:30:09 pm
content: I've been looking for a decent digital microscope and the experience has been a minefield of potential missteps. One thing I haven't been able to figure out is why there are different housings/listings for what appears to be the same product.Both of these appear to have the exact same specs and lens options with the main difference being the housings.Is there a logical reason for this outside of the perception of variety?https://www.aliexpress.us/item/2251832096757196.html?pdp_npi=4%40dis%21USD%21US%20%24122.71%21US%20%2499.76%21%21%21122.71%2199.76%21%402103244817349188778317690e6b48%2112000018262955686%21sh%21US%210%21X&spm=a2g0o.store_pc_allItems_or_groupList.new_all_items_2007473398579.32283071948&gatewayAdapt=glo2usa#nav-descriptionhttps://www.aliexpress.us/item/2255799858945483.html?pdp_npi=4%40dis%21USD%21US%20%24101.36%21US%20%2494.86%21%21%21101.36%2194.86%21%402103244817349188778317690e6b48%2112000027246796025%21sh%21US%210%21X&spm=a2g0o.store_pc_allItems_or_groupList.new_all_items_2007473398579.4000045260235&gatewayAdapt=glo2usa#nav-specification

author: thm_w
author_rank: Super Contributor
timestamp: December 24, 2024, 11:40:43 pm
content: One has the connectors coming out of the top, one on the side. Either may work better depending on your setup.Also looks like first one doesn't have IR remote input.They are both c-mount thread.https://www.aliexpress.us/item/2251832096757196.htmlhttps://www.aliexpress.us/item/2255799858945483.html

author: u666sa
author_rank: Frequent Contributor
timestamp: December 25, 2024, 03:45:58 am
content: That's the camera I have on my trinacular micoscope. Kind of funny you guys adding a lenz and calling it a microscope.1080p @60fps USB2.0I've tried soldering looking at monitor, it's doable.But I'd be looking for 120fps if I wanted a microscope like that.
Early 1970s SOLID STATE TV parts bonazza - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 08, 2017, 02:57:14 am
content: I went to work and there it was just down the block, a great big floor model Zeninth Chromacolor II (not sure the actual model yet), but luckily on wheels. At 1st I was just going to get tools and pick at it where it was, but I rolled it into the garage.Some wires were already cut like from the flyback transformer, and the CRT had the end cracked off. So I just started scavenging it.-big mains transformer, 2 other mid-sized ones, an audio trans, flyback trans, and a little one-lots of nice custom wound inductors of all size-lots of ceramic and other types of old caps that probably fine-big high watt resistors and some wire wound ones I believe-at least 2 big power MOSFET type transistors on nice huge heatsinks, multiple other old custom Zenith/Texas Instruments socket-ed transistors-some custom Zenith/Texas Instruments 14pin DIPs, some in sockets-a bunch of variable resistors that seem to turn fine-metal shielding cansThats all on the main huge metal chassis thats mostly some copper plated steel. Lots of random stuff on there yet to pluck. The date codes are mainly 1973I'm hoping there's a big air core variable capacitor, but I'm not sure, I never looked at the channel switchers yet.There were 2 fuses (so far) the smaller 1 was popped. And I found a MOV disc rattling around, without leads attached, looks like the solder melted off. I only saw 1 place that looked a bit burnt on a "PCB". Tomorrow in the sunlight I'll have a much better look around for damage.Now time to test a few of the inductors and look up some transistors.Hopefully the big and medium transformers work, so I can start planning a linear PSU
Early effect in BJT - Page 1
Forum section: electronics / beginners

author: Connoiseur
author_rank: Regular Contributor
timestamp: August 13, 2015, 02:17:12 am
content: I was wondering what is the significance of Early effect in BJT's from the circuit design point of view. Does it have any pitfalls/advantages? I mean, does it influence the switching ON/OFF time hFE etc. I've never seen it being mentioned in any of off the shelf transistors (like bc547, 2n2222, 2n3055......), yet it is an important topic in almost all of the electronics books.

author: c4757p
author_rank: Super Contributor
timestamp: August 13, 2015, 02:53:05 am
content: It is not strong enough to be of note for most common discrete BJT applications these days. It can absolutely ruin old-fashioned discrete analog stuff though, the stuff that's usually done on a chip. For instance, if you make a simple current mirror (the output impedance of which should ideally be infinite), the Early effectdominatesits output impedance. Same with accuracy in differential amplifiers - if you try to make an op amp from scratch and the collector-emitter voltages of the two transistors in the core differential pair are not close to equal, you can have some pretty serious error.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 13, 2015, 05:25:12 am
content: By definition, Early effect IS the output impedance of a non-cascode type current source/sink (straight mirror, not Wilson or cascode).Some geometries and types have more than others; apparently some RF types have it in the extreme, so that even using them as followers, the gain is rather low. On the other hand, some have it so slight that it's hard to tell if they're positive or negative resistance (if you wait for the tempco to act, they do indeed go negative).Tim
Earth fault/loss in isolated systems - Page 1
Forum section: electronics / beginners

author: lilmantis
author_rank: Contributor
timestamp: April 28, 2016, 04:20:42 pm
content: I'm having some trouble understanding how the Earth fault/loss in isolated systems is done (SMPS isolation transformer for 220V to 24V, loss/fault detection is done on secondary side). Does anyone know some resources on the subject?

author: lilmantis
author_rank: Contributor
timestamp: April 28, 2016, 04:26:31 pm
content: How/What will I measure on the secondary since this is isolated from the primary?
earth ground on transformer connector on pcb? - Page 1
Forum section: electronics / beginners

author: snailFury
author_rank: Contributor
timestamp: January 20, 2015, 04:56:43 am
content: If I have a PCB with a power supply circuit on it. Should my connector to the transformer have a third wire port for an earthground? Or is that unnecessary?

author: Monkeh
author_rank: Super Contributor
timestamp: January 20, 2015, 05:01:16 am
content: You tell us, do you need an earth connection to that circuit?

author: Monkeh
author_rank: Super Contributor
timestamp: January 20, 2015, 05:10:44 am
content: These are not questions I like seeing from people playing with big generators..
Earth Grounding Metal Chassis  - Page 1
Forum section: electronics / beginners

author: Kdog44
author_rank: Contributor
timestamp: March 24, 2015, 08:10:00 am
content: As a rule of thumb, if you have an electrical circuit in a box (metal) that is using the mains voltage, you should always earth ground the box. Is that correct for almost every application?

author: Zero999
author_rank: Super Contributor
timestamp: March 24, 2015, 09:20:32 am
content: Generally yes but even this won't cover you fully.The resistance between the case and the earth conductor should be under 0.1Ohms. The minimum resistance between live, neutral and earth should be >1MOhm with a leakage current of no more than 1mA.The earth connection should also be made with a shake proof washer so it doesn't become disconnected.However there are ways to design a product so the case doesn't need to be earthed which can achieved by insulating all of the mains conductors with reinforced or double insulation, so no single fault can cause the case to be live. If you don't understand this then always earth the case.

author: macboy
author_rank: Super Contributor
timestamp: March 24, 2015, 03:15:51 pm
content: Quote from: Hero999 on March 24, 2015, 09:20:32 amThis is referred to as doubled-insulated or Class II or Class 2. It is acceptable to have an ungrounded metal chassis on such equipment. A common example is audio equipment, which have metal chassis that are practically never grounded in order to avoid ground loops which cause hum. This is not something to play with since it requires specific construction and testing. For mains powered projects, ground all metal cases, and do it well.

author: aveekbh
author_rank: Regular Contributor
timestamp: March 24, 2015, 03:43:25 pm
content: Quote from: macboy on March 24, 2015, 03:15:51 pmThe resistance between chassis and earth <0.1 ohm is intended to ensure that fuses/circuit breakers trip immediately if the chassis becomes live and removing the source of dangerous voltages.In general, any exposed metal should be connected to earth/protective ground. And even then, it is always good practice to double-insulate your mains wiring (use heat shrink on the connectors, put your mains wiring in another tube, etc). This will reduce the chances of exposing mains voltages to the low voltage parts of your circuit.

author: Zero999
author_rank: Super Contributor
timestamp: March 24, 2015, 03:50:55 pm
content: Quote from: macboy on March 24, 2015, 03:15:51 pmTypo, obviously, corrected.
Earth on Attens 936b soldering iron. - Page 1
Forum section: electronics / beginners

author: dhead
author_rank: Newbie
timestamp: December 09, 2012, 12:00:52 pm
content: Hi.I'm a bit new to electronics and I hope I don't mix up some of the technical terms.I wanted a soldering station with a variable temperature control, I really couldn't afford a Hakko one as it would cost me about 200$, so I got myself a cheap 50$ Attens 936b (the same as the previous model of Sparkfun soldering station).I've needed to replace the power plug from an Aussie one to European, so I decided also to have a look inside the chassis.What I found is that the phase and neutral from mains are switched according to the silkscreen on the pcb.That made me thinking a bit...1. Why the wall (foundation) earth is connected to a device with non conductive casing ? is it so that the voltages would be earthed referenced ? so after passing the transformer one of the leads should be connected to the earth ? I guess (I'm not sure, please confirm that) connecting the earth to the ground plane on the pcb.2. If the above is true then why the earth wasn't connected to the ground plane ? is it possible they decided to connect the soldering iron tip to the earth as a safety measure ?

author: T4P
author_rank: Super Contributor
timestamp: December 09, 2012, 12:53:43 pm
content: It's "ESD SAFE" for a reason. You don't want ESD collecting on your iron
Earth wire connected between primary and secondary of isolated offline SMPS - Page 1
Forum section: electronics / beginners

author: ocset
author_rank: Super Contributor
timestamp: July 31, 2018, 07:20:39 pm
content: We are noticing in many isolated offline SMPS’S , that there is an insulated earth connection wire connected between primary and secondary…it connects to output ground. Would you agree that this is for the purpose of preventing the SMPS output from floating up to high voltage levels with respect to Earth ground?

author: ArthurDent
author_rank: Super Contributor
timestamp: July 31, 2018, 07:51:43 pm
content: Yes, but not to any current carrying primary wire. Only to the ground (earth) wire that comes from the wall outlet.

author: Gyro
author_rank: Super Contributor
timestamp: July 31, 2018, 07:55:02 pm
content: An odd question treez.Yes, many SMPSs have grounded outputs. It provide a solid ground reference for whatever the SMPS is powering, for safely, static discharge protection, preventing Y cap leakage etc.[Edit: I'd probably go as far as to say thatmost3 pin input SMPSs provide a grounded output]

author: Giaime
author_rank: Regular Contributor
timestamp: August 01, 2018, 08:12:46 am
content: I think it's odd instead. Most SMPS I've seen are SELV type output, so they provide a basic insulation w.r.t. PE.Many SMPS have a PE wire from primary side to secondary side, but that's just to connect to PE the output Y caps, for noise reduction.

author: lordvader88
author_rank: Frequent Contributor
timestamp: August 07, 2018, 07:40:17 am
content: I thought they usually have a blue, high voltage cap from pri to sec gnd. But I've only really worked on computer PSUs and little wallpack types.
Earthed metal sheet under breadboard - Page 1
Forum section: electronics / beginners

author: Muffins
author_rank: Regular Contributor
timestamp: November 20, 2020, 07:42:58 am
content: Hi guys,I have a breadboard with a microcontroller set up on my desk. I was noticing that the microcontroller was becoming unresponsive when I moved around sometimes. Then after some experimentation I noticed that rubbing my feet around on the carpet seemed to stop the microcontroller every time.Thinking this was some sort of electrostatic interference problem I put a sheet of aluminium under the breadboard and earthed the sheet. It now seems to be immune to feet on the carpet.What exactly is going on here?

author: Zero999
author_rank: Super Contributor
timestamp: November 20, 2020, 06:40:22 pm
content: The varying electric field induced a voltage into the conductors on the breadboard, causing the microcontroller to malfunction. By adding a sheet of aluminium underneath, you shielded it from the electric field. Breadboards are terrible for interference, both increasing the likelihood of pick-up and transmission. It works the other way round. I remember building a 74LS00 astable mulitivibrator, which flashed a coupled of LEDs, on a breadboard, when I was a child and it caused clicking noise an an FM radio, on the other side of the house. No doubt if I built it on a proper PCB, it wouldn't have caused as much interference.
Easiest way to get into external RAM interfaces - Page 1
Forum section: electronics / beginners

author: soFPG
author_rank: Frequent Contributor
timestamp: April 22, 2021, 04:00:08 pm
content: Hello,I would like to get into external RAM interfaces (such as SDRAM, DDR1 etc.) - what would be the easiest way to do this?I think the STM32F4-Series has some microcontrollers which have a external multi-purpose bus interface.I also thought about using an FPGA where I can directly model the memory controller.What would you recommend?
Easiest way to get phase shifted PWM signals - Page 1
Forum section: electronics / beginners

author: KOR
author_rank: Newbie
timestamp: November 14, 2021, 12:27:04 pm
content: Hi for a project I need 4+ PWM signals at 150-300khz (adjustable) the main problem is that those PWM signals need to be adjustable in their phase. So for example PWM1 starts high for 1µs PWM2 gets high at 1.2µs for 1µs and so on.So I want control of the frequency, phase shift and the duty cycle of all PWM signals.theoretically the teensy family would be totally capable but I have never programmed registers and it seems very confusing.Is there an easy way to achive such a goal without programming registers or learning FPGA programming?thanks

author: ledtester
author_rank: Super Contributor
timestamp: November 14, 2021, 02:02:37 pm
content: I found these posts on the pjrc forum which might point you in the right direction:https://forum.pjrc.com/threads/68600-Teensy-4-1https://forum.pjrc.com/threads/42158-PWM-phase-shift-help
Easiest way to power android phone without a battery - Page 1
Forum section: electronics / beginners

author: supergogetassj5
author_rank: Newbie
timestamp: February 04, 2018, 05:32:53 pm
content: Hi. I know you can't power it with 5v from usb, but how to make it lower, I don't know. How do I power my android without a battery correctly, so I don't fry it? Also, I will keep it on all the time, not just sometimes. Thanks for any info.

author: Signal32
author_rank: Frequent Contributor
timestamp: February 04, 2018, 06:00:24 pm
content: Use a buck regulator to turn the 5v into 4.0V and apply that to the battery terminals.Still, this may not work indefinitely because the phone is expecting the "battery" to discharge ... who knows how it will treat this situation. Depends on the phone firmware.
Easiest way to regulate 12V from solar charged battery?? - Page 1
Forum section: electronics / beginners

author: Dunk_c
author_rank: Contributor
timestamp: November 20, 2016, 01:20:39 am
content: Hi EveryoneCan I get some advice please.I have a solar charged SLA bank that has an absorption voltage that gets up to 15v when it is cold. I have noticed that the DC-DC laptop charger I use on the battery cannot maintain a stable 19v output when the batteries are being charged at the higher voltages. Any ideas why?This prompts me to find an easy way to make/buy a 12 instant voltage DC regulator. It would have to cope with maybe 200w of output as I sometimes have two laptops charging. I have read about LT3790. Are there any Chinese converters online using this?Is there a simple solution such as buying several cheap eBay buck/boost synchronous converters and using the in parallel to get the power needed?If not I'll just run off the inverter but I think this is less efficient and would prefer to stay at 12v and round trip through 240v.Thanks

author: Dunk_c
author_rank: Contributor
timestamp: November 21, 2016, 09:56:43 am
content: Anyone there?

author: Chalcogenide
author_rank: Regular Contributor
timestamp: November 21, 2016, 10:11:59 am
content: What kind of voltage variation are you suffering? It's quite strange that the boost converter cannot maintain regulation, unless you are somehow exceeding the input voltage limit of the IC. Does the battery voltage drop significantly under load? When batteries are cold, not only the voltage might increase but the ESR increases quite a bit so maybe this could be causing the issue as well.

author: Dunk_c
author_rank: Contributor
timestamp: November 21, 2016, 10:30:08 am
content: It is varies rapidly between ~17v and 19v when battery is at 14.6v. When battery is is floating at 13.6v, the DC-DC converter is able to hold 19v stably. Sorry for my vague initial description.Can buck converters cope with continuously varying input voltage and maintain constant output voltage?

author: Seekonk
author_rank: Super Contributor
timestamp: November 21, 2016, 01:04:54 pm
content: Frankly, I am not sure what you are trying to say. Silicon Chip had a boost converter for a car that had to have a diode or two in series with the battery in order to boost properly. Some boost converters need to boost at least 2V over supply in order to work properly. I don't think that is the problem here.
East Tester ET33 series waveform generator. - Page 1
Forum section: electronics / beginners

author: mikkyboy
author_rank: Newbie
timestamp: September 09, 2023, 07:17:18 pm
content: Hello to all. Newbie question for all. I have just purchased an East Tester ET3320C from AliExpress, but the unit was supplied without software. Been onto the manufacturer asking where can the software be downloaded from, still no answer. Have also posted on Facebook asking the same question. So has anyone out there managed to find software for this unit. Many thanks in advance.
easy amplifier circuit - Page 1
Forum section: electronics / beginners

author: Nickk2057
author_rank: Regular Contributor
timestamp: July 16, 2015, 02:42:26 am
content: so... am trying to find out a way to make a amplifier circuit that i can run my speakers with clear sound. anyone know what works good that can run on 12V DC?

author: Marco
author_rank: Super Contributor
timestamp: July 16, 2015, 03:17:06 am
content: Lots ofa cheap modulesout there (for this particular chip there isan articlewhich describes how to mod the circuit for a better performance).

author: Simon
author_rank: Unknown
timestamp: July 16, 2015, 06:02:02 am
content: https://www.google.co.uk/search?q=tda2005&espv=2&biw=1536&bih=783&tbm=isch&imgil=08ckCL2Tz9qEhM%253A%253BBvl_JNDtyL1gjM%253Bhttp%25253A%25252F%25252Fwww.electroschematics.com%25252F7870%25252Ftda2005-audio-amplifier-circuits%25252F&source=iu&pf=m&fir=08ckCL2Tz9qEhM%253A%252CBvl_JNDtyL1gjM%252C_&usg=__yMzwqcxwLiPYId_Z2-4mOeF-nSY%3D&ved=0CCwQyjdqFQoTCNWAxuj83sYCFcZWFAodQUYAng&ei=s0inVZXbEMatUcGMgfAJ#imgrc=CCwnZTL4qbG1AM%3A&usg=__yMzwqcxwLiPYId_Z2-4mOeF-nSY%3D
Easy schematic - calculating voltage - Page 1
Forum section: electronics / beginners

author: nForce
author_rank: Frequent Contributor
timestamp: November 15, 2018, 05:41:07 pm
content: How to calculate voltage in the node point (blue)?If the resistors had all equal value then it would be just the average voltage of all voltage sources.

author: mvs
author_rank: Frequent Contributor
timestamp: November 15, 2018, 06:32:00 pm
content: Quote from: nForce on November 15, 2018, 05:41:07 pmKirchhoff's current law:I1+I2+I3=0Ohm's law:I1=(U1-U)/R1I2=(U2-U)/R2I3=(U3-U)/R3Calculation:(U1-U)/R1+(U2-U)/R2+(U3-U)/R3=0(-1.5-U)/100+(0-U)/150+(5-U)/200=0 | x600(-9-6U)+(-4U)+(15-3U)=0-13U+6=0U=6/13=0.4615 V
Easy way to adjust a signals DC offset - Page 1
Forum section: electronics / beginners

author: Pasky
author_rank: Regular Contributor
timestamp: March 17, 2014, 03:55:22 am
content: I have a video circuit that goes into an encoder that requires a positive DC offset in order to 'kick on' due to transistors biasing. The video input has a 0 DC offset so it needs to be raised about 100mV. I had some help from a friend and this circuit ended up working:This allowed me to adjust the DC offset up or down 300mV. However I'm curious what other methods there are available to do this, that aren't very complicated and use just as few parts. What if I needed a much higher range for offsetting the DC voltage such as -5V to +5V? What could I use then?Thanks.

author: mhzghz
author_rank: Contributor
timestamp: March 17, 2014, 05:10:30 am
content: You should add a 100 kohm or so resistor in series with the wiper to isolate the pot R1 from the video circuit.Be sure the coupling capacitor C1 can handle the DC offset. Use a bipolar cap to be safe.For larger DC offsets, or the "proper" way to add a DC offset to a video signal, is with a op-amp rated for video bandwidths. That's how PLL locking of video transmitters is done.Here is an example schematic, using an EL2020:http://qsl.net/n9zia/atv/23cm_atv.png
Easy way to get a 500mA load for testing? - Page 1
Forum section: electronics / beginners

author: Jay112
author_rank: Regular Contributor
timestamp: May 16, 2016, 02:30:07 pm
content: I'm sorry for this simple question, and I feel like the answer should be obvious to me, but...I'm trying to test some triacs using this simple SCR tester circuit that I got from this page:http://www.sentex.ca/~mec1995/tutorial/triacs/triacs.htmlThe triacs I'm trying to test have a 500mA latching current, but I'm having trouble thinking up a way to get a 500mA load. I can get the triacs to switch on using the circuit above, but I can't test their latching ability because I need a greater load. Can you please give me some suggestions for how I can make/find a 500mA or greater load?Thanks!

author: Delta
author_rank: Super Contributor
timestamp: May 16, 2016, 02:35:07 pm
content: A lamp, just like your picture shows!6W at 12V is 500mA, so try a car sidelight or indicator bulb...

author: klr5205
author_rank: Regular Contributor
timestamp: May 16, 2016, 02:55:45 pm
content: A simple current mirror can be made with 3 parts: a transistor, a resistor, and a diode (or diode-connected transistor)The other obvious answer is of course just a 24 ohm resistor.

author: Jay112
author_rank: Regular Contributor
timestamp: May 16, 2016, 03:02:38 pm
content: Quote from: Delta on May 16, 2016, 02:35:07 pmThanks for responding! I couldn't seem to find any lamps that are higher than 500mA. The best I could find was a 1W 12V LED.Quote from: klr5205 on May 16, 2016, 02:55:45 pmThanks for the info! I'll have to study about current mirrors now, and I'm sure that'll be useful to me in the future. But I think the obvious answer of just using a resistor was what I was looking for. My mind wasn't working well because I'm tired of concentrating on circuits since yesterday.

author: karoru
author_rank: Regular Contributor
timestamp: May 16, 2016, 03:08:22 pm
content: Quote from: klr5205 on May 16, 2016, 02:55:45 pmDiscrete current mirror for half an amp, what can go wrong...

author: rstofer
author_rank: Super Contributor
timestamp: May 16, 2016, 03:22:48 pm
content: Quote from: Jay112 on May 16, 2016, 03:02:38 pmTail light/brake light bulb should be available at an auto supply store.5 each 1/2 Watt 100 Ohm resistors in parallel - 600 mA

author: Jay112
author_rank: Regular Contributor
timestamp: May 16, 2016, 03:52:53 pm
content: Quote from: rstofer on May 16, 2016, 03:22:48 pmThanks! I actually could have used the advice about putting them in parallel, because I forgot to match the power rating of the resistor! I got my dosage of magic smoke for the day.

author: Chris Mr
author_rank: Regular Contributor
timestamp: May 19, 2016, 03:57:18 pm
content: I have a reel of nichrome wire I use to make up dummy loads.If you wrap it round a sheet of something you can use a croc clip to vary the resistance.In your case though I would use a light bulb - diagnostics
Easy way to remove brown insulating tape? - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: April 04, 2018, 12:10:00 am
content: Is there an easy way to remove the brown insulating tape you find in li-ion battery packs?I've been a little successful just using an exacto knife and scraping away at it, but I'm wondering if there is an easier way. Maybe I'll try sanding it away / working at it with a rotary tool.I just need to remove enough to solder to the underlying strip.And what is that brown tape called?

author: remerle
author_rank: Newbie
timestamp: April 04, 2018, 12:19:33 am
content: Quote from: ledtester on April 04, 2018, 12:10:00 amIt's Kapton tape.

author: Whales
author_rank: Super Contributor
timestamp: April 04, 2018, 12:34:16 am
content: Are you referring to the thing right at the tip of the cell, stuck to the terminal you want to solder to? It may actually be a flexible PCB, so it could be some sort of resin.The stuff down the side of these cells indeed appears to be kapton.

author: ledtester
author_rank: Super Contributor
timestamp: April 04, 2018, 01:28:57 am
content: Its definitely some sort of tape/film. Here's another pic.

author: Whales
author_rank: Super Contributor
timestamp: April 04, 2018, 04:14:30 am
content: Looks similar to flexible PCB material. Could be kapton. Could be another resin.Apart from suggesting you try a wide variety of abrasives or solvents, I'm not sure, sorry.

author: ledtester
author_rank: Super Contributor
timestamp: April 06, 2018, 03:46:45 am
content: Turned out using rotary tool with an abrasive attachment worked well enough.
EasyEDA – Changing Schematic after Trace Layout - Page 1
Forum section: electronics / beginners

author: JLynch
author_rank: Contributor
timestamp: July 29, 2021, 05:34:07 pm
content: So this might be a rather dumb question here but I have the schematic done and finished laying out the traces when realized a resistor was missing. So if I now go back to modify the schematic to add in the resistor will I have to rework all of the traces once again?Thanks.

author: tooki
author_rank: Super Contributor
timestamp: July 29, 2021, 05:51:23 pm
content: No. Update the schematic, save it, then update the PCB. You’ll just have an unplaced component, and possibly a rule violation for any traces that connected in the old schematic but shouldn’t in the new one.
EasyEDA to Eagle? - Page 1
Forum section: electronics / beginners

author: ssashton
author_rank: Frequent Contributor
timestamp: October 13, 2020, 04:35:52 pm
content: If I look at parts available on LCSC.com they only offer EasyEDA models. Is there a way to export to Eagle 7?

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: October 13, 2020, 05:30:50 pm
content: Without really knowing, probably not. But in most cases it should be a standard footprint which Eagle should have so all you really have to do is the schematic symbol.
ebay 0.1 - 2000MHz 32dB LNA DOA - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: February 05, 2023, 11:14:18 pm
content: Just got my LNA to test with my SDR and it came DOA. Draws no current. Any guess as to what mimic is used on this - chip says MDt, dot is connected to VCC?https://www.ebay.com/itm/225029683793

author: anmony
author_rank: Newbie
timestamp: February 06, 2023, 03:48:22 am
content: Based on some Amazon reviews of the same amplifier (https://www.amazon.com/gp/product/B01N2NJSGV), check to make sure the resistor attached to VCC is labeled "221" (220 Ohm) instead of "222" (2200 Ohm). The pictures of your ebay link show "222", which is likely wrong (at least for 9-12V input).Not all of the Amazon reviews are relevant unfortunately, as some reviews/pictures show a different package LNA with a different bias connection, and no one seems to have identified the IC on your version of the board.In any case there are reviews mentioning current draws of 20-40mA. If you have a board with a 2200 Ohm resistor, 20-40mA of current is a voltage drop of 44-88V, so you would probably need to supply something like 50V for it to work. Of course at that voltage/current the resistor would be dissipating around 1W and would probably cook itself pretty quicklySo if you have a board with a 2200 Ohm resistor, you probably need to swap it out for 220 Ohm to make the board usable.

author: metrologist
author_rank: Super Contributor
timestamp: February 06, 2023, 01:44:17 pm
content: That sounds exactly what the problem is, a misloaded resistor! It's 222... I measured ~5mA current, not enough for my power supply to show.
Ebay "alice" 5 digit panel Digital Voltmeter - Pre-purchace confusion - Page 1
Forum section: electronics / beginners

author: Cliff Matthews
author_rank: Unknown
timestamp: December 14, 2016, 01:42:49 am
content: Alice110198 is trusted by many here, but I don't want to buy 4 x $4.52 pieces of crap. They state 3 things I'd like some clarity on:1) measurement range of0-33.000V over the traditional 0-20.000V header<<-- Say what? Traditional?2)update rate: > 3s/time<<-- 3 seconds between adc conversion updates? Why so slow?3) Precision automatic change below 4.3 V, the highest resolution of 0.1 mV, Precision automatic 4.3 V above changes, the highest resolution of 1 mV Connection is simple,just need to pick up two lines, a joint reverse protection, then do not burn<<-- I prefer not to burn anything.. I have multiple positive outputs sharing the same ground and I'll power all these by a separate LM317.http://www.ebay.com/itm/Red-LED-5-Digit-DC-0-4-3000-33-000V-Digital-Voltmeter-Voltage-Meter-Car-Panel-/400490355805

author: StillTrying
author_rank: Super Contributor
timestamp: December 14, 2016, 02:32:35 am
content: Big thread on them here.https://www.eevblog.com/forum/projects/$5-voltmeter-with-5-digit-(0-1mv)-resolution/

author: rrinker
author_rank: Super Contributor
timestamp: December 15, 2016, 12:42:57 am
content: I bought one of those cheapy kind, just to try it out. Connected to my HP power supply and BM235 and it was pretty close. There's (crapper) trimt ont he back, I tweaked it slightly (tongue at the correct angle) and across the range of the power supply it's actually no more than 1 lsd off the reading of my meter and that's usually just rounding.

author: Cliff Matthews
author_rank: Unknown
timestamp: December 15, 2016, 01:26:27 am
content: Quote from: rrinker on December 15, 2016, 12:42:57 amI saw one close-up pic, so I looked-up the 20-pin STM part.. Only 10-bit ADC's, but it's good to hear somebody had a positive result.Was that within the last 6 months? I ask because when the demand goes up, the quality goes down (missing bypass caps etc..).

author: StillTrying
author_rank: Super Contributor
timestamp: December 15, 2016, 02:12:43 am
content: According tothe other threadthere's a MCP3421 18 bit ADC on it, which would make more sense than a 10bit.http://www.microchip.com/wwwproducts/en/en520011Possible schem.http://eddy-em.livejournal.com/73375.html

author: Cliff Matthews
author_rank: Unknown
timestamp: December 15, 2016, 02:39:36 am
content: Quote from: StillTrying on December 15, 2016, 02:12:43 amRight you are! In a quick skim-over, my eyes completely passed-over a 6-pin diminutive I2C as an opamp or tvs..Mouser wants $2usd each on a 3k reel, so China must be price dumping these meters. How can they make a profit?
Ebay ACS712-05 modules - Page 1
Forum section: electronics / beginners

author: Sparc
author_rank: Contributor
timestamp: October 09, 2016, 07:57:24 am
content: I got a few ACS712-05 current sense modules off ebay to play with. I found the output voltage does not change with input current in the expected way. ACS712 datasheet states output should have a sensitivity of 185mV/A. I measured 132mV/A. Rise time should be 3.5us for ACS712. I measured 50us. Very slow.Thinking something was wrong, I searched digikey. Seems there was a ACS704-05 and ACS706-05 parts that did have a 133mV/A sensitivity. The pinout is also slightly different between 712 and 704/706. 712 has a filter function on pin 6. On ACS704/706 pin 6 is connected internally to pin 7. I removed the filter cap and found that pins 6 and 7 were connected internally inside the IC. I got a magnifier and looked at the IC. It has a rough look to it. Like, maybe it had been sanded and repainted... Geez. It looks like someone found obsolete parts and relabeled them or is producing an old design and labeling them as ACS712. Should this be surprising? If they were the older ACS704/706, why not just sell them as that? The circuit board doesn't even match the chip. More crap from china.

author: Simon
author_rank: Unknown
timestamp: October 09, 2016, 08:03:00 am
content: Yes you got done, what you expect eBay and China that's called being screwed to the square. (And I am an eBay seller myself) the part number looks to me like an Allegro part and to be honest their datasheets are at best a whimsical promise of specifications. Buying from eBay in China something like that does not sound like a good idea to me. In the past I've been recommending Lima sensors these are apparently very good.

author: italiancow
author_rank: Newbie
timestamp: April 06, 2025, 05:38:58 am
content: I know this is a very old post, but I thought it worthwhile to point out that I have been using ACS712 modules like that off eBay for about 4 years (2021 to present 2025). My experience with them is 50/50. Half of them appear to use "real" chips and work perfectly to spec. The 05 version outputs 2.5v (within about 20 mV) and deviates at 185mV / A, just like it should.The other half are total garbage. Either they deviate by 100 or 133 (indicating possible use of other chips that they relabledas ACS712), or they sit at some other wild voltage, like 4.2, with no current being measured, and don't deviateat all.My best advice, if you buy these from eBay, is to pay close attention to the photos. If the labelingon the board near the output pins is relatively large and crisp, AND, it goes GND OUT VCC across the top of the 3 pinheader, there's a good chance it's real. The ones that are labeled in reverse, VCC OUT GND, or have small or roughprint, are usually junk.

author: BillyO
author_rank: Super Contributor
timestamp: April 06, 2025, 03:30:07 pm
content: Having VCC OUT GND makes no sense at all from a layout perspective given that Vcc is pin 7 and Gnd is pin 5 pin the chip. Who ever laid out that board obviously couldn't have given a damn about what they were doing.
Ebay Digital Ammeter, Shunt Required? - Page 1
Forum section: electronics / beginners

author: Brown
author_rank: Contributor
timestamp: October 20, 2015, 08:27:34 pm
content: Hi EEV Forum!Do I need a shunt resistor for this ammeter?http://www.ebay.ca/itm/140891198308Thanks!

author: Simon
author_rank: Unknown
timestamp: October 20, 2015, 08:30:04 pm
content: I don't think so, but with that sort of "ingrish" anything is possible.

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 20, 2015, 08:37:49 pm
content: If it was an old moving coil meter with a fixed scale of 0-5A it could be that it needs an external shunt, but this digital one advertised as 0-5A should have a shunt already, otherwise it would not be 0-5A but a volt meter. But like Simon says (no pun intended) you can expect anything from these China sellers.

author: ez24
author_rank: Super Contributor
timestamp: October 21, 2015, 03:43:11 am
content: Here is another one that show more on the wiringYours looks like it has two wires but must have four like this one, notice the shunt on the back. I suggest you buy one that has more details like this 3 amp model:http://www.aliexpress.com/item/0-36-5-Digits-0-3-0000A-DC-Ammeter-Digital-amp-Ampere-panel-Meter-Red-LED/32314115899.html?spm=2114.01020208.3.31.kmIhNZ&ws_ab_test=searchweb201556_6_71_72_73_74_75,searchweb201527_2,searchweb201560_9

author: Brown
author_rank: Contributor
timestamp: October 21, 2015, 07:04:22 pm
content: Thanks for the help guys!

author: kripton2035
author_rank: Super Contributor
timestamp: October 21, 2015, 07:24:37 pm
content: generally for these small amp meters, you need a shunt for modules that measure > 10Aunder 10A no need for a shunt, it's already implemented in the module
ebay Digital Voltmeter strange values - Page 1
Forum section: electronics / beginners

author: jan18101997
author_rank: Newbie
timestamp: July 09, 2016, 07:16:05 pm
content: I am trying to use a Digital Voltmeter from ebay to measure the the voltage and the current usage from a batterie.strange values: it is showing me about about 10A if i just use about 5AI am connecting it like this (Attatchment)ebay item:http://www.ebay.de/itm/221799389984my question is how can i get this to work?

author: Twoflower
author_rank: Frequent Contributor
timestamp: July 09, 2016, 07:50:10 pm
content: There are several possible issues.Have you tried to use a separate power source for the supply? It could be possible that this meter need an insulated power supply.The *bay description indicates two ranges (50A and 100A) is there anything to configure? Like a jumper for example.

author: jan18101997
author_rank: Newbie
timestamp: July 09, 2016, 09:45:08 pm
content: If i use an external source everything works. you have to order them in the range you need it range (0-50)

author: Twoflower
author_rank: Frequent Contributor
timestamp: July 09, 2016, 10:18:55 pm
content: So if you're using an independent supply the displayed range is correct? The problem is that the potential of the supply GND is not the same of the main battery.That probably means there might be no simple solution. The only idea I have is to use a switching regulator for the power supply which insulates the input from the output (not all do the trick). The only ones I found during a quick search require a 12V input with +/-10% accuracy (e.g. SIM1-1212).

author: jan18101997
author_rank: Newbie
timestamp: July 11, 2016, 06:02:10 am
content: Constant 12 V will not be this easy but still thanks i will give it a try.Or temporally i just use a 9v battery.

author: Brumby
author_rank: Unknown
timestamp: July 11, 2016, 07:11:36 am
content: I've seen some variations of this module that are claimed to work off a common supply for the module and load.One of those shows the negative of the module supply disconnected altogether. Presumably it gets negative power for the module through the current sense circuitry.No guarantees obviously, but it might be worth a try.

author: stj
author_rank: Super Contributor
timestamp: July 11, 2016, 09:50:58 am
content: you should have got one that uses an inductive loop,that would be one less problem.

author: StillTrying
author_rank: Super Contributor
timestamp: July 11, 2016, 04:49:38 pm
content: Quote from: stj on July 11, 2016, 09:50:58 amThey're not very good at DC.
Ebay meter test leads - Page 1
Forum section: electronics / beginners

author: mikeys
author_rank: Contributor
timestamp: May 14, 2016, 01:47:40 pm
content: Has anyone bought Fluke probes off Ebay? They're ~ £15 cheaper than other places I can find them, concerned they might be fakeshttp://www.ebay.co.uk/itm/Fluke-TL71-Hard-Point-Test-Leads-Digital-Meter-Probes-TL-71-/251729302361?hash=item3a9c3c5359:g:gBEAAOSwr81USfkv

author: GreyWoolfe
author_rank: Unknown
timestamp: May 14, 2016, 08:31:51 pm
content: They probably are fakes. I just looked at TEquipment.net, authorized Fluke dealer, and their price is $28.85 USD. Check out Frankie's store on eBay and look at the Brymen leads. I have a set and I like them:http://www.ebay.com/itm/Brymen-Silicone-Gold-Plated-Test-Leads-Probes-for-Multimeters-CAT-IV-1000V-/171162377470?hash=item27da129cfe:g:uSQAAOxyTjNShpch

author: mikeys
author_rank: Contributor
timestamp: May 14, 2016, 09:04:06 pm
content: Aye I thought they'd either be fakes or someone's skimming them from the factory. Either that or reselling some Chinese-market only probes.I'll pick up a couple of sets of those Brymens instead, thanks.

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: May 14, 2016, 09:21:38 pm
content: I don't know if that listing is fake or not, even if they are they may still be a good set of leads.Unless Fluke branding is important to you, another option is to look at Pomona, they make the Fluke test leads and you can pick up Fluke test leads with the Pomona branding and not be concerned about the quality.Quote from: GreyWoolfe on May 14, 2016, 08:31:51 pm

author: casinada
author_rank: Frequent Contributor
timestamp: May 15, 2016, 02:08:41 am
content: I bought a set of Agilent from here:http://www.ebay.com/itm/252365990854?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITThey are nice and have a black and red minigrabbers, one aligator and one sharp tip.

author: xbb
author_rank: Newbie
timestamp: May 15, 2016, 02:49:27 pm
content: Quote from: blacksheeplogic on May 14, 2016, 09:21:38 pmI also suggest this, look for example at Pomona6365(straight plugs) or5519A(L shaped plugs, same as TL-71).They also come in kit with alligator clips and tip extenders (look for 6344 and 6343)

author: Bryan
author_rank: Frequent Contributor
timestamp: May 16, 2016, 08:15:56 am
content: Quote from: xbb on May 15, 2016, 02:49:27 pmI had a pair of the Pomona's 6365. Super sharp, but not very durable. Mine lasted a couple months and one of the leads became detached internally.
Ebay rework station strange noise - Page 1
Forum section: electronics / beginners

author: mmrvelj
author_rank: Newbie
timestamp: December 22, 2018, 07:34:56 pm
content: I recently bought YIHUA 995D rework station from ebay. Device looks better than I expected, however when I turn on soldering iron, the station produces a strange noise during heating.I recorded a short video to show this (it is not very loud, but you can definitely hear it on video) herehttps://youtu.be/84kLIx4G7NQSoldering iron works but this noise is annoying. What do you think could be the cause, and could I fix it somehow?

author: t1d
author_rank: Super Contributor
timestamp: December 23, 2018, 01:19:52 pm
content: I could not hear it, at all. But, common sound issues with this type unit would be transformer hum and/or a loud fan. Some transformer hum might be considered normal. But, excessive noise can be due to...- Loose transformer mounting bolts. Try just tightening them, snugly. Do not bare down and strip them out.- No rubber pads, between the case and transformer frame. If not present, maybe add them. But, be sure to maintain the ground, somehow.- Poor electrical connections, causing the transformer to labor. Try gently compressing any loose spade connections.- A cheap transformer, lacking proper internal wire insulation/potting.As for the fan, same as the transformer... Loose mounting bolts... No mounting rubber grommets... Cheap quality...Remember, opening the case can void the warranty. Use proper safety techniques, if you do. Unplug the unit and drain the capacitors, for sure.

author: ToddCraix
author_rank: Newbie
timestamp: December 24, 2018, 05:03:25 am
content: Nie wiem, ile możesz mi pomóc uzyskać te informacje, ponieważ chcę uzyskać dostęp do wielu informacji, nie wiem, jak mi pomóc?

author: wraper
author_rank: Unknown
timestamp: December 24, 2018, 05:07:05 am
content: Transformer is buzzing when AC current flows through it. Pretty common, nothing to worry about. Often heater can buzz as well.
eBay SMD 1% resistor assortments - Page 1
Forum section: electronics / beginners

author: jgalak
author_rank: Regular Contributor
timestamp: January 23, 2018, 06:29:49 pm
content: There are a ton of kits on ebay with SMD resistor assortments, some claiming 1% tolerances. Has anyone gotten these? Do they really meet spec? I'm somewhat dubious of ebay items like this, but, otoh, the prices are quite attractive.

author: Microcheap
author_rank: Frequent Contributor
timestamp: January 23, 2018, 07:16:14 pm
content: I normally order from Aliexpress, I found it is normally cheaper for me than eBay, but any way, I bought a few of these resistors and they look to meet the specs:https://www.aliexpress.com/item/Free-shipping-0805-1-SMD-Resistor-Kit-10Ohm-910KOhm-80valuesX25pcs-2000pcs-Chip-Resistor-Assorted-Kit-Samples/32788152037.htmlI use it only for some hobbyist level prototypes, I wouldn't trust in any chinese parts from ebay or ali for anything more serious.You being in the US I would thought you have plenty of options of more reputable sources with accessible prices

author: jgalak
author_rank: Regular Contributor
timestamp: January 23, 2018, 07:30:10 pm
content: Quote from: Microcheap on January 23, 2018, 07:16:14 pmSure, but that sort of kit from Digikey is about an order of magnitude more money....I'm strictly a hobbyist. I mostly want a kit for those cases where I want to determine correct values experimentally. Filters, for examples, or amplifier bias/gain/feedback resistors. Some time, you need to play with the values.I have assortments of pth resistors, but more and more of what I'm doing is smd devices on custom PCBs. Doesn't make sense to leave room for pth components (not to mention higher lead inductances).

author: james_s
author_rank: Super Contributor
timestamp: January 23, 2018, 08:00:53 pm
content: In my experience they're ok. I have only had a few assortments and I haven't measured a large sample but the ones I have checked were within tolerance. I think a 1% resistor is common enough now that even the fake ones are usually ok. I still wouldn't use them in production hardware but they're good enough for hobby projects, always seems to be at least one value I forget to order when I'm building something, or one that I have to change from my original calculation.

author: Yansi
author_rank: Super Contributor
timestamp: January 23, 2018, 08:30:17 pm
content: SMD resistors are so cheap to make, it is hard to believe anyone would even attempt to fake those. A whole resistor reel costs a a couple $ (I can buy 5kpcs SMD0603 Yageo reels for $4-5).Capacitors are however a bit different matter, specifically those with higher capacitance or when a well behaved dielectric (NP0/C0G) is required.