hybridfree/eevblog-posts huggingface dataset:
a new multimeter big issues - Page 1
Forum section: electronics / beginners

author: aek
author_rank: Newbie
timestamp: January 02, 2016, 12:59:40 am
content: helloi would like to buy a new multimeterafter doing some research i m considering to buy one of thoseamprobe 520uni-t ut61euni-t ut139cit is for electronics (arduino-led ....)and some single phase AC uses ( measuring current voltage ) precision is not so important for me , input protection morebudget under 75 dollarsthanks

author: LA7SJA
author_rank: Regular Contributor
timestamp: January 02, 2016, 01:27:01 am
content: I would buy the uni-t ut61e as a first choice and the ut139c as a more economical choice. I do not know the Ampro but it's the only no TRMS of the 3.Johan-Fredrik

author: crispy_tofu
author_rank: Super Contributor
timestamp: January 02, 2016, 02:21:26 am
content: The input protection of the UT61E is probably the worst out of the three though... There is a GS (European) version of the UT61E with better protection, but it's more expensive...(The UT61E below in the comparison is the non-European version)

author: Lightages
author_rank: Unknown
timestamp: January 02, 2016, 03:40:21 am
content: The UT139C is TRMS. I would recommend that over the UT61E.

author: cs.dk
author_rank: Unknown
timestamp: January 02, 2016, 07:57:03 am
content: Really a longshot, but Brymen BM805 is ~70 USD at TME.eu - It's a basic meter from their "old" series, no fancy features. But at least the input protection can be somewhat trusted i think.

author: aek
author_rank: Newbie
timestamp: January 02, 2016, 09:36:21 am
content: help plz

author: andybarrett1
author_rank: Regular Contributor
timestamp: January 02, 2016, 11:33:55 am
content: Why not put Fluke 17b in the mix ??

author: crispy_tofu
author_rank: Super Contributor
timestamp: January 03, 2016, 09:47:46 am
content: Quote from: andybarrett1 on January 02, 2016, 11:33:55 amOn eBay, Fluke 17B+s are going for about USD 110, which is above the OP's budget. Not sure about 17Bs (for some reason Amazon is selling them for $148 - ripoffs)...

author: andybarrett1
author_rank: Regular Contributor
timestamp: January 03, 2016, 09:10:16 pm
content: Was just a suggestion ... Never sure of exchange rates !+1 re:- Amazon 17b
A nice video about capacitors .  - Page 1
Forum section: electronics / beginners

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 03, 2011, 07:42:42 pm
content: Well I do not use to post threads with youtube videos.But this one, is so well made and worthy .Check it out ..

author: TheDirty
author_rank: Frequent Contributor
timestamp: May 03, 2011, 08:08:12 pm
content: I totally forgot about Afrotechmod's. He's got lots of good video's and some new ones since I last looked at his channel.
A power bank still detects a connected device if I disconnect USB's VBUS - Page 1
Forum section: electronics / beginners

author: epigramx
author_rank: Regular Contributor
timestamp: March 06, 2019, 12:01:22 pm
content: Do you know of a way to do it - in a standard way - without disconnecting the entire cable? Would disconnecting only GND do it (will try that next if no one answers)?PS. In case anyone wonders why, it's because I can't change the power bank's model/brand and it doesn't fast-charge itself, if anything else is connected to it.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: March 06, 2019, 12:33:50 pm
content: what about a cable with a built-in switch:https://www.ebay.com/itm/1-3-pcs-Micro-USB-Power-Cable-with-ON-OFF-Switch-for-Raspberry-Pi-Durable-/132925734304

author: amyk
author_rank: Super Contributor
timestamp: March 06, 2019, 01:06:34 pm
content: It senses the data lines too.

author: epigramx
author_rank: Regular Contributor
timestamp: March 06, 2019, 01:22:59 pm
content: Another forum suggested to just switch the GND because it will make the other pins float. I guess I'll try that next.Quote from: malagas_on_fire on March 06, 2019, 12:33:50 pmI'd rather avoid that due to cost and space. Plus, it probably only does what I already do (since it's called "power cable").Quote from: amyk on March 06, 2019, 01:06:34 pm

author: epigramx
author_rank: Regular Contributor
timestamp: March 10, 2019, 01:41:27 pm
content: success, dangling GND made the power bank completely oblivious anything is connected to it.

author: bson
author_rank: Unknown
timestamp: March 11, 2019, 02:48:49 am
content: The host doesn't care if a device is attached to Vbus or not. What it detects is pullups on the data lines.

author: epigramx
author_rank: Regular Contributor
timestamp: March 13, 2019, 06:04:13 am
content: Quote from: bson on March 11, 2019, 02:48:49 amSo I guess it detects a specific range of resistance between GND and D+ or/and D-.

author: bson
author_rank: Unknown
timestamp: March 13, 2019, 06:50:47 am
content: Depends; different pullups indicate different speed... so the pullups are used to both detect the presence of a device and its speed.For USB 2, a 1.5k pullup on D+ to +3.3-5V indicates Full Speed.A 1.5k pullup on D- indicates Low Speed.A high speed device connects as FS and then goes through a special reset cycle (a chirp) to bump the speed to HS.

author: epigramx
author_rank: Regular Contributor
timestamp: March 13, 2019, 06:59:07 am
content: Quote from: bson on March 13, 2019, 06:50:47 amSince this is only a charger in effect (a power bank) I guess it only detects anything in that range.If they are floating, I assume it considers it higher than that impedance. Correct me if I'm wrong.update: It's Quick Charge 2.0 compliant so it does deal with D+/D- actively.
a problem with sec/div knob on front panel of Tek2465b - Page 1
Forum section: electronics / beginners

author: franksummerrain
author_rank: Newbie
timestamp: August 09, 2016, 04:34:52 am
content: Hi guys,problem: The sec/div knob can't be pull out to intensify the waveform.what I have done: I have tear down the front panel and no idea to do next. Seems to need to solder some points to see the knob circuit.Thanks for any suggestions and solutions.

author: dacman
author_rank: Frequent Contributor
timestamp: August 09, 2016, 09:48:40 pm
content: If I had it, I'd try to loosen it with some LPS-1.
A product similar to MicroRax - Page 1
Forum section: electronics / beginners

author: Tony R
author_rank: Regular Contributor
timestamp: June 22, 2012, 12:16:56 am
content: If you have not heard of MicroRax (Like me until today) they are a modular building set like an old style erector set.http://www.microrax.com/http://www.sparkfun.com/search/results?term=MicroRax+&what=products(about 1:30)I think they are a great idea but the price is a little high for me, and it got me thinking, there has got to be something similar to this out there somewhere.What I would really like is to find a product that is modular like this, but if I need to do some cutting or drilling I wont be crying that I'm destroying my expensive set.So, has anyone heard of anything similar to this?This may not be electronic related but I think it would be great for making larger cases and such.
A question about a schematic  - Page 1
Forum section: electronics / beginners

author: Asim
author_rank: Regular Contributor
timestamp: September 08, 2013, 02:17:04 pm
content: Hi guys, i have a silly questioncan you explain the connection on the node before C11 ( what is connected to what ?)http://www.electronics-diy.com/img/TX200.jpg

author: fcb
author_rank: Super Contributor
timestamp: September 08, 2013, 02:34:23 pm
content: Shows a separation of the two parts, screening can basically.

author: Asim
author_rank: Regular Contributor
timestamp: September 08, 2013, 02:37:19 pm
content: so C9 & C10 are connected to that node ? what about that short circuit to the ground ?

author: JuKu
author_rank: Frequent Contributor
timestamp: September 08, 2013, 03:27:45 pm
content: As I read this, it is a connector, just like input and output. Connector shield goes to ground and is decoupled to +9 by C9 and C10, but not to C11.

author: fcb
author_rank: Super Contributor
timestamp: September 08, 2013, 04:31:50 pm
content: You wouldn't need (or want) a connector in that position.It's a cheap FM bug design, you would have a two part screening can (really...?) to prevent feedback/noise/etc.. from the amplifier hitting the modulator/osc.
A question about capacitance and capacitors - Page 1
Forum section: electronics / beginners

author: Carlsp
author_rank: Newbie
timestamp: March 20, 2019, 05:22:22 pm
content: Hello everyone.I am fixing a pet dryer, a big hair dryer for pets. The main capacitor on the controller board has gone bad. It is a 2.0 uF MPX X2 Suppression Film Capacitor. My question is, is there a big difference between a General Film Capacitor and a Suppression Film Capacitor? The reason I am asking is that I can get a 2.0 uF General Film Capacitor or a 2.2 uF Suppression Film Capacitor and I am not sure which one to use. Should I use the 2.2 uF Suppression cap as the original is a suppression cap or should I use the General Film Cap because it is the correct value? Any suggestions or info would be greatly appreciated. Thanks.

author: Gyro
author_rank: Super Contributor
timestamp: March 20, 2019, 05:30:08 pm
content: Hi, For an 'across the mains' suppression application, it is a safety requirement that you use a suitable X2 (or X1) safety certified part. I don't think 2.2uF is too big a difference.EDIT: Wait, is this a capacitive dropper resistor for the controller electronics? If so, it is a little more important to be close to the correct value. 2.2uF is probably still ok. You didn't mention the voltage rating and dielectric of the 2uF one you found.

author: DannyTheGhost
author_rank: Contributor
timestamp: March 20, 2019, 06:23:41 pm
content: When capacitor fails - it gets shorted or just losing its 'capacitive' behaviour. When capacitor, placed between mains, fails - what you would prefer - shorting mains or second variant? This is what X1/X2 class means - it is designed for supressing EMI surges and when it fails - it won't short mains and make blackout in your house

author: Benta
author_rank: Super Contributor
timestamp: March 20, 2019, 07:39:06 pm
content: The "X2" specification is key, as well as working voltage (and value). Do not compromise here, but get the right part.
A question about clamp meter operation - Page 1
Forum section: electronics / beginners

author: Mule
author_rank: Contributor
timestamp: July 28, 2017, 01:09:57 pm
content: Hello,Every clamp meter I have ever used when on the DC current setting, the reading ranges by about 200mA when no conductor is inside the clamp. Some meter readings even range just by rotating the meter with the clamp closed.Now my question is why is this? Especially in the case where you can rotate the meter and it changes the reading. Both these cases are without conductors inside the clamp. I am curious as to what is going on inside the meter.Many thanks,

author: Zbig
author_rank: Frequent Contributor
timestamp: July 28, 2017, 01:13:53 pm
content: Blame the Earth's magnetic field

author: Jeroen3
author_rank: Super Contributor
timestamp: July 28, 2017, 05:43:28 pm
content: DC clamp meters use a hall sensor to measure current. This hall sensor measures magnetic field.Due to this, they are especially vulnerable to permanent magnets and transformers.They often are off by a huge amount if the core of the 1:many transformer (the clamp) does not close properly. They can also be magnetized by high dc currents or long time use. Use it on AC to remove this offset.

author: Zero999
author_rank: Super Contributor
timestamp: July 28, 2017, 09:55:24 pm
content: Use the rel. or zero function with no conductor in the clamp, to make sure the reading is zero before using it. If the meter doesn't have a zero or rel. function then it's crap: you'll just have to remember the figure or write it down and deduct it from the reading.
A question about DRAM - Page 1
Forum section: electronics / beginners

author: Fantasma25
author_rank: Regular Contributor
timestamp: October 28, 2013, 12:16:20 am
content: Ok, so I'm starting to get into using RAM memory for my FPGA projects, but I'm not sure about this. According to what I've seen online, you have to refresh the data stored in a DRAM module so that it doesn't go away. But does that mean that you have to rewrite every single bit you stored?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 28, 2013, 12:29:41 am
content: No. You need to periodically do a refresh command, which refreshes a whole row. You do not need to send any data, just cycle through all row addresses over a period of a few mS. On some devices, they will generate the address internally so all you need to do is intiate a refresh cycle with no address or data.Though you can refresh as often as you like, and it is tempting to just throw in a reffresh cycle when the memory isn't doing anything, but this pulls a lot of power and they get rather hot!Look at SDR SDRAM, not DDR, as it's a lot easier to drive. I recommend Micron's datasheets as being very well written - the protocols are the same for most makes so it applies fairly generally
a question about industrial tariffs, maximum demand and load factors - Page 1
Forum section: electronics / beginners

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: November 04, 2013, 01:25:53 pm
content: i know this is more of an electronics forum but i am prety sure that some users here know a thing or two about electrical powerThe question i am trying to answer for one of my assignments is 'why are industrial tariffs based on maximum demand and load factor?'does any one know any good and credible websites or know them selves why energy company's use maximum demand and load factors to calculate how much to charge the consumer?

author: SeanB
author_rank: Super Contributor
timestamp: November 04, 2013, 06:41:19 pm
content: Industrial use max demand and power factor as they then charge based on cable size. This provides an incentive for large users to be more flexible in loading, often they will have a few of the bigger continuous operating motor loads done with a synchronous motor that is over driven to get a leading power factor, and this is used to control the overall power factor for the whole plant, or at least large parts that work together. Along with this you schedule large loads such that they are operated in sequence, so you draw a reasonably constant power from the supply network. Some larger plants actually have large gensets that they synchronise to the mains to reduce peak demand as needed to cut the power demand to a level below the point where the supply cost increases a large amount. Often this also is done because the feeders are at max load and they do not want to step up to the next size ( along with all the switchgear, large transformers and the associated digging and larger substations needed) as then the cost per unit also rises.

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: November 06, 2013, 08:09:36 pm
content: I see, thank you very much.So i am right in saying that they charge less if the industrial premesis spread there work load over a longer period of time so that there maximum demand is lower, thus allowing te electrical supplyer to install a cheaper / less powerful feeder to the premesis, and because the load is spread over a larger amount of time the stress on the electricity network is reduced.Is a syncronus motor better then using a power factor correction capacitor?Also what is genset?
A question about oscillators - Page 1
Forum section: electronics / beginners

author: Fantasma25
author_rank: Regular Contributor
timestamp: March 23, 2014, 06:40:20 pm
content: Hello. I'm trying to design an audio effects board using a DSP form Analog Devices (ADAU1701), but I'm not sure about the oscillator part. In the datasheet it saysbut I'm not sure which one I should buy since I don't really know what they mean by "AT-Cut Parallel Resonator" (link to digikeyhttp://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&KeyWords=12.288) or if I should do something like thisThis second schematic is for the FT2232 that is on the hercules launchpad. I showed it because the oscillator connection in its datasheet is very similar to the one in the datasheet of the ADAU1701. What should I do?Thanks!

author: Paul Price
author_rank: Super Contributor
timestamp: March 25, 2014, 10:59:03 pm
content: http://www.digikey.com/product-detail/en/ABM7-12.288MHZ-D2Y-T/535-9837-6-ND/2001708spec sheet shows AT-CutAlmost all commonly sold xtals for this freq. are AT-Cut, so almost anything you can buy will work fine, just use the recommended xtal circuit as shown in the AnDev spec sheet

author: VK5RC
author_rank: Unknown
timestamp: March 26, 2014, 12:27:40 am
content: The second circuit to me, looks almost identical except the case of the crystal is grounded, usually only needed in rf environments (or noisy & fast digital)
A question about oscilloscopes' bandwidth - Page 1
Forum section: electronics / beginners

author: mehdi
author_rank: Regular Contributor
timestamp: December 02, 2015, 11:21:20 am
content: HiI've an R&S (Hameg) HMO1002 base model (50MHZ bandwidth)You can upgrade the license to a 70 or 100MHZ bandwidth.I connected the output of my signal generator to this oscilloscope and was able to see frequencies above 50MHZ (even 125MHZ)How's that possible?What am I doing wrong?Thanks

author: VK5RC
author_rank: Unknown
timestamp: December 02, 2015, 11:29:59 am
content: This is normal, the flat response bandwidth is what is specified, there is a slow roll off of amplitude as you go above this point till very little at double the frequency, this is important in Digital scopes to avoid aliasing of very high frequency/out of range signals giving false lower frequency signals appearing on the screen.

author: Srbel
author_rank: Frequent Contributor
timestamp: December 02, 2015, 12:02:09 pm
content: You are not doing anything wrong. 50 MHz bandwidth means that the signal that oscilloscope is showing, at 50 MHz, will have -3 dB (or 0,707) of the actual signal amplitude. Oscilloscope is still capable of showing signs of higher frequencies, but their amplitude will be lower the higher you go.Your scope has a sampling rate of 1Gsps. So you could even maybe see a signal of 500 MHz, but it will have very low amplitude (if any) and will only show it as triangles.

author: w2aew
author_rank: Super Contributor
timestamp: December 03, 2015, 07:32:28 pm
content: As others have stated, the BW simply indicates the guaranteed 3dB bandwidth of the vertical response. Here's a video I did on the subject a while back with an analog scope:and one using a older digital oscilloscope:
A question about the humble resistor (Manufacturing process) - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: December 20, 2023, 01:51:02 pm
content: I spent about 15 minutes looking for videos on making carbon through hole resistors in the 1960s/1970s; pre CAM. No joy.Qabillions made each year.Bake a carbon surround, cut to length/value, insert two leads. Coat with insulator. Sort by tolerance. Apply value stripes. Pack.I looked at Periscope Films on Internet Archive, youtube, etc. Anyone know of a video that shows the production line in detail (not just drawings)?Regards,Dewey
A question about the implementation of multi-frequency copy remote control - Page 1
Forum section: electronics / beginners

author: pdskill
author_rank: Newbie
timestamp: July 15, 2024, 01:46:48 pm
content: Hello everyone,I am a beginner in radio frequency. I have a question about sub1ghz. I have a copy of a remote controller with multiple frequencies. I took it apart and found that the silk screen of the main control was polished, and there was also a polished radio frequency chip. But I guessed from its crystal oscillator and packaging that it is a sub1ghz chip from China, codenamed cmt2300a (my guess). My question is, how does it receive the transmission signal in the case of unknown frequency? Can't the sub chip only receive one frequency at the same time? How is it done?

author: tggzzz
author_rank: Super Contributor
timestamp: July 15, 2024, 05:37:57 pm
content: In your near-duplicate post, this is a relevant questionhttps://www.eevblog.com/forum/rf-microwave/how-to-receive-multiple-frequencies-simultaneously-through-a-sub1ghz-chip/msg5573819/#msg5573819
A question about this LED driver/ shift register. - Page 1
Forum section: electronics / beginners

author: cvriv
author_rank: Frequent Contributor
timestamp: March 12, 2020, 04:51:28 am
content: https://www.digikey.com/product-detail/en/stmicroelectronics/STP16CPC05MTR/497-8525-1-ND/2021196I read through the datasheet and there wasn't enough there for a noob like me to fully understand how it works. The only thing I need to know is whether it's a sink or source?I thought it was a source because it said the output voltage is 0 - 20V. I know it's constant current, so I thought the output voltage woupd fluctuate to keep the current where I want it.After hooking it up, as a source, it just doesn't work at all. I have the LED cathodes connected to ground. Some of the LEDs are on but very dim. I'm staring to think that's driver current leakage.The only thing I havent done yet was to reverse the polarity of the LEDs. What can someone with experience tell me about these?Thanks.

author: floobydust
author_rank: Super Contributor
timestamp: March 12, 2020, 05:02:43 am
content: The datasheet Fig. 6 shows open-drain outputs so it can only sink current. It's not a great datasheet, I find it vague and a little confusing.The LED common must be the +ve rail as in Fig. 17 with the LED cathodes connected to the IC.

author: cvriv
author_rank: Frequent Contributor
timestamp: March 12, 2020, 06:21:02 am
content: Thank you much. I don't have a lot of experience understanding those schematics. I'm learning though. Thanks.
A question about using a BM 867 Brymen. - Page 1
Forum section: electronics / beginners

author: eternalpurple
author_rank: Newbie
timestamp: January 06, 2018, 11:20:09 pm
content: I just bought a Brymen 867 multi meter and have read the instructions. I see no where in there that it explains anything about how to compensate for the resistance of the leads. Does it need to be done and if so...........................How do you do it. I'm hoping someone here has one and can help me out...........Thanks

author: IanB
author_rank: Super Contributor
timestamp: January 06, 2018, 11:28:21 pm
content: It only matters when measuring low resistances less than about 10 ohms. You just hold the leads together and press the \$\Delta\$ button to null out the offset before taking the measurement.

author: Terry01
author_rank: Frequent Contributor
timestamp: January 06, 2018, 11:35:42 pm
content: They are a great meter to use, I use mine almost daily and still can't believe how much features you get for the £££ or $$$You'll enjoy using it!

author: eternalpurple
author_rank: Newbie
timestamp: January 06, 2018, 11:53:48 pm
content: Thanks for the help. It seems to be a very well made piece of equipment. I have only just started to use it so time will tell. It's nice to find a board where people from other countries hang out. That way you have a chance to get an answer 24/7.

author: Terry01
author_rank: Frequent Contributor
timestamp: January 07, 2018, 12:48:28 am
content: Yes it's a well made unit for sure! It hangs with my Fluke 177 all day long no sweat at all!Even when I make mistakes probing things I shouldn't or lose concentration for a few seconds and silly things like that. It matches the Fluke step for step on accuracy easily and gives more resolution when needed too. I don't need these extra things only doing hobby stuff but it is nice to see the extra digits showing you exactly what's happening where the Fluke just more gets to the point. It's nice to have the luxury too rather than a meter that goes wanting.Enjoy!
a question, need help with tracing common ground pads to pins  - Page 1
Forum section: electronics / beginners

author: walidantar
author_rank: Newbie
timestamp: July 10, 2025, 11:09:29 pm
content: hello, i need help with tracing common ground pads to ground pins, i'm using diptrace, i drew a trace from the first pad to the last pad, it by normal passes through the other pads, is it right or physically the pads in between will not be connected?another question, is placing a thought-hole pattern over the smd pads of the pattern of a smt variation of the same/exact component, so i can use either connector through-hole or smd version as i i used the smd connector i use the holes as via pads - is this ok?the application is mounting raspberry-pi pico on a keybed - scanning switching diode matrix as 8 columns (outputs) by 16 rows (inputs w/ pull-down resistors) .. by the way anybody here is familiar with such applications? using adfruit tinyusb (test midi example) did resolved a lot of issues and the mcu got detected as midi device but still need to write the code for declaring the gpio pins and the function to scan the diode matrix

author: PGPG
author_rank: Frequent Contributor
timestamp: July 11, 2025, 08:40:35 am
content: Quote from: walidantar on July 10, 2025, 11:09:29 pmThink a moment. Both pads and tracks are made from the same copper layer. It is not possible for track to go through pad and be not connected with it.
A question of gain notation. - Page 1
Forum section: electronics / beginners

author: Aethelstan
author_rank: Contributor
timestamp: February 10, 2018, 04:08:34 pm
content: Hello, up front I must state this question does relate to an assignment I am working on. I am converting gain for op amps between arithmetical and dB, and I understand the maths but I am a little confused regarding the actual notation for the two scales. If I have a gain of 20dB, is that simply G=20dB, or do I use the unit for power gain of GP? If I use that, do I use the notation of GVfor arithmetical gain? Or, should I simply use G and the unit of dB or unit-less V/V signifies which type of gain I am talking about?Thanks

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 10, 2018, 04:39:09 pm
content: In my experience there are no robust conventions for this. It would save some trouble if there were. In documentation I generate I explicitly define the notation I use. In documentation I am reading I am very cautious about assuming usage, and often have to run a series of calculations to figure out the authors usage.If your professor has not expressed a strong preference just document what you do. (Run through some test cases to make sure you are self consistent.)

author: tggzzz
author_rank: Super Contributor
timestamp: February 10, 2018, 04:48:07 pm
content: I would use "gain of 10" or "gain of 20dB". If I thought it might be ambiguous or might clarify a point, I might use "voltage gain of 10" or "gain of 10V/V".

author: Zero999
author_rank: Super Contributor
timestamp: February 10, 2018, 04:58:34 pm
content: I've always used AVfor voltage gain and just A for power gain.In any case, it should be fairly obvious whether voltage or power is being discussed, by the context.
A quick(ish) MOSFET tutorial  - Page 1
Forum section: electronics / beginners

author: Sivand12
author_rank: Contributor
timestamp: November 18, 2014, 11:16:56 am
content: Here is the Introductory video.

author: PODF
author_rank: Contributor
timestamp: February 27, 2015, 05:55:17 pm
content: thanks, this video helpt me a lot.but i have a question with the VGS. In the case of the IRFZ44N from this video (http://www.irf.com/product-info/datasheets/data/irfz44n.pdf). Can i run this MOSFET with VGS only +5V and get around 10A switched? Figure 3 tells me that this is working (by the way, how do i read this graph? where is it starting at +5V? 10A? 12A? 20A? 50A??? the squares in this figure are asymmetric). Is this ok to run MOSFETS like this? Or is this bullshitt? Is the resistance much higher when VGS i only +5V? I dont see a RDS graph in relation to VGS??

author: retrolefty
author_rank: Super Contributor
timestamp: February 27, 2015, 09:57:47 pm
content: Quote from: PODF on February 27, 2015, 05:55:17 pmNo, a 'logic level' mosfet is what is required for 5vdc VGS drive. Lots to choose from.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: February 27, 2015, 10:24:30 pm
content: Quote from: PODF on February 27, 2015, 05:55:17 pmIt's a logarithmic scale, that's why the lines aren't linear. The first horizontal line above 10 is 20, then 30, 40, and so on up to 100, then the next line is 200, 300, etc.Read the caption on Figure 3. That's the drain to source current with a Vds of 25V. You can see that at a Vgs of 5V and a Vds of 25V you get ~20A at room temperature, which is an Rds of over an ohm. If you want to run 10A through it, you'll be dropping around 12V across Vds and burning around 120W in the MOSFET. At least for a few milliseconds until it dies.

author: PODF
author_rank: Contributor
timestamp: March 02, 2015, 11:06:00 am
content: Thanks suicidaleggroll, for the scale and for the Vds of 25V-hint.I thought this Figure shows that at Vgs 5V there could only be 20A transferred.But thats wrong, it more shows the resistance of the MOSFET.so, i have to go the top of Figure 3 to get the least resistance.Minimum Vgs 10V in this case.
A quick(ish) MOSFET tutorial - Page 1
Forum section: electronics / beginners

author: Jebnor
author_rank: Regular Contributor
timestamp: June 25, 2014, 09:33:49 pm
content: I found this quick little 6 part MOSFET tutorial by Julian Ilett. I thought some beginners would like to benefit from it.Playlist URL is here:https://www.youtube.com/playlist?list=PLjzGSu1yGFjUgTVkhb4WslOVDNAZ3K4yRHere is the Introductory video.
A quick question about terminal strips - Page 1
Forum section: electronics / beginners

author: smackaay
author_rank: Regular Contributor
timestamp: January 25, 2013, 05:51:37 am
content: I have a whole bunch of wiring I have to do on a project and since this thing is going to be around for a while I'd like to do it the best way possible. I'm using terminal strips, like screw down barrier blocks with plates that hold the lead down. Now a quick question, is it better to tin the twisted wire with a bit of solder or just twist it and let it crush flat under the plate?

author: Biff383
author_rank: Regular Contributor
timestamp: January 25, 2013, 06:12:51 am
content: I just smush them. Be very carefull of wild ends though.

author: nanofrog
author_rank: Super Contributor
timestamp: January 25, 2013, 06:19:35 am
content: Don't tin the wire. They're not designed for it, and the wire tends to come loose if you do.Do you have a pic of it or a link of what you're using?Depending on the terminal strip, it could be designed for bare wire or crimp terminals, such as a bootlace ferrule, ring, fork,... For example, if it has leaves (metal tabs that hold the wire <i.e. have a V shape in them>, not directly by the screw), then it's probably meant for bare wire. If it's just a screw, maybe with a washer just under the screw head, you'll want to use a crimp terminal.

author: DaveW
author_rank: Frequent Contributor
timestamp: January 25, 2013, 11:40:39 am
content: Tinning the wire tends to cause the solder to run up the wire and create a location for the wire to fracture, so bare stripped wires are better. Crimping a bootlace ferrule over the ends is a good method, particularly if you're planning to remove & reinsert the wires frequently. If you're not, a robust method is to pass a wire all the way through the terminal block, twist or solder the two wires together and then pull it back into the terminal block. You can then tighten the screws onto the insulation of the wires which gives a good resistance to mechanical shocks

author: smackaay
author_rank: Regular Contributor
timestamp: January 25, 2013, 01:18:05 pm
content: Awesome, thanks you guys!

author: ptricks
author_rank: Frequent Contributor
timestamp: January 25, 2013, 01:33:33 pm
content: If you are using the kind sometimes called barrier strips then I recommend soldering on some of the locking fork ends that have heat shrink tubing:http://www.mouser.com/ProductDetail/3M-Electronic-Specialty/MH14-14FLK/?qs=sGAEpiMZZMvlOED0T0kTWilPHsjT7bfz
A really beginner about guitar pickup inductance with a Hantek 6022BE - Page 1
Forum section: electronics / beginners

author: Jetfixxxer
author_rank: Newbie
timestamp: August 28, 2014, 08:36:52 pm
content: Let start off with I'm total newb when it comes to scopes. I'm a hobbyist I can read schematics, build guitar effects, use my Fluke189 on various things.I recently started to wind my own pickups and wanted to check the inductance on the pickup. I was going to go with a CGM-101http://www.syscompdesign.com/CGM-101_ep_56-1.htmlfrom Syscomp. Then being the person I am I picked up a Hantek 6022BE because cost less and had good reviews. I was also looking at one of those cheap Chinese function generators on ebay. The combo of both will still me less than the CGM-101. Then I read that the Hantek 6022BE FW is driver based. So now I have reservation about the unit about future updates and improvements.My question after being long winded. Will I be able to use the Hantek to check the resonant frequency and plot it?I always wanted a scope so I could expand myself when it came to troubleshooting pcb's and what not.I also going have to set some time aside to view the video's posted here on Oscilloscopes.

author: Paul Price
author_rank: Super Contributor
timestamp: August 28, 2014, 09:49:55 pm
content: You can make a simple variable frequency oscillator with just a LM358, just takes a very few components, connect your pickup across a capacitor, something between .1uF and 1 nF Apply the output of the VFO to the pickupu/cap circuit though a 10K resistor, using a pot connected as a frequency control on the LM358 sawtooth VFO circuit below, then just connect your scope across the pickup/cap and turn the pot and you will see the resonant frequency as a sharp rise in the mV range on your scope.You connect a 1K to 10k pot to +Vcc (let us say at the positive of a 9V battery powering this circuit), other side of pot to ground, the center of the pot goes to the +VC* point shown on the schematic below.The transistor in the circuit can be any general purpose npn transistor such as 2N3904 etc.The resonant freq is 1/((2*pi* (SqrRoot(*L*C))) or the 1/Period that you see the best peak to peak action at on your scope.Hope you can do the math.http://www.allaboutcircuits.com/vol_2/chpt_6/2.htmlAs far as the Hantek, goes, here is a really bad review of the software that is used with it:http://www.google.dk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCgQtwIwAQ&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DbEuPtWE8FOI&ei=X6T_U5XDAaShyAOS74HQCw&usg=AFQjCNG0bdw79SXhE1KxNaTC1HhfT45fpQ&bvm=bv.74115972,d.bGQ

author: Jetfixxxer
author_rank: Newbie
timestamp: August 29, 2014, 01:06:40 am
content: Thank you for the schematic. Now as far as math well that wasn't my strong subject in school.I watch that video when I was looking around. I think I will return the Hantek and get the SysComp.Thanks

author: beauty2003tt
author_rank: Contributor
timestamp: March 26, 2015, 03:25:14 am
content: First of all, I'm a really beginner here.Should I ask where can I post here?I did not find the button of "Post"...Really need your help
A replacement for an old PNP transistor - Page 1
Forum section: electronics / beginners

author: FatalityX
author_rank: Newbie
timestamp: September 09, 2019, 05:55:52 pm
content: Hello everyone, I'm looking for a replacement for this transistor (https://www.datasheet4u.com/datasheet-pdf/Rohm/B1357/pdf.php?id=944128) from an old Casio keyboard (CT 770) that I'm trying to fix. Thanks.

author: magic
author_rank: Super Contributor
timestamp: September 09, 2019, 07:01:29 pm
content: It seems there are some on eBay. Maybe genuine, I'm not sure if they would bother faking a nonstandard package like this one.Search for the full name: 2SB1357.

author: kripton2035
author_rank: Super Contributor
timestamp: September 09, 2019, 07:05:42 pm
content: all these are possible replacements :https://alltransistors.com/crsearch.php?mat=Si&struct=PNP&pc=20&ucb=60&uce=60&ueb=5&ic=3&tj=175&hfe=120&caps=TO126

author: MagicSmoker
author_rank: Super Contributor
timestamp: September 09, 2019, 07:11:08 pm
content: It's difficult to give a recommendation without knowing exactly how this BJT is being used, but *most* of the time the specific part isn't too critical.The package - TO-126 (aka TO-225) - is practically obsolete, but DigiKey, somewhat to my surprise, lists about 40 parts in stock in that package. A few possible substitutes from that list are MJE171G, KSB1151YS, BD440S, BD788G, 2N5195G.

author: richnormand
author_rank: Unknown
timestamp: September 09, 2019, 08:35:33 pm
content: NTE378.Not exact mechanical replacement but should be OK if you cannot find the original.
A rose by any other name would smell as sweet...  But this? - Page 1
Forum section: electronics / beginners

author: Rick Law
author_rank: Super Contributor
timestamp: November 17, 2013, 11:07:57 pm
content: Greetings, If you don't mind firing a few brain neurons for me, I can use your help.What do you call this? (photo attached)This is for the alligator clip to clip on-to. I've searched for hook, eye, clip pin, clip loop, clip mount, clippee... No luck. Just can't find the darn thing to buy without knowing the right name.ThanksRick

author: Skimask
author_rank: Super Contributor
timestamp: November 17, 2013, 11:11:27 pm
content: Looks like a .2" jumper, something that a guy might clip after a one-time programming.

author: David_AVD
author_rank: Super Contributor
timestamp: November 17, 2013, 11:15:48 pm
content: I'd try "test point".

author: Psi
author_rank: Super Contributor
timestamp: November 17, 2013, 11:30:51 pm
content: I don't think they are intended for test points.You see them on PC motherboards quite a lot to hold the chipset heatsink on.There's a metal spring hook which attaches to two of these on opposite corners

author: Rory
author_rank: Frequent Contributor
timestamp: November 17, 2013, 11:47:27 pm
content: Found it. It is a BGA solder anchor. Here's a link to one. Search term 'bga solder anchor' in your favorite search engine comes up with lots of hits.http://www.aavid.com/products/bga/solder-anchors

author: Rick Law
author_rank: Super Contributor
timestamp: November 18, 2013, 05:31:39 am
content: Thanks, guys! The solder-anchor I had was indeed removed from an old PC mother board long time ago. I've seen it in an electronic video some where used for an alligator clip. I was going to get a few to use for alligator clip connector.I was pulling my hair out trying to find it! Heat sink was simply not in my mind! I kept searching under variation of gator-clips.The solder-anchor does look like it works well for a gator clip. I didn't know there is such thing call "test point (connector)". Looking at images of these "test point connectors" found on google, some look like just a bend wire. May be I should just bend a wire into a U shape solder that in and call it a day.

author: notsob
author_rank: Frequent Contributor
timestamp: November 18, 2013, 05:35:23 am
content: Test Connectors - this may help to give you an idea on what is availablehttp://www.toby.co.uk/content/catalogue/series.aspx?id=6&Category=31
A silly question Darlington transistor vreg - Page 1
Forum section: electronics / beginners

author: electronics man
author_rank: Frequent Contributor
timestamp: January 20, 2014, 06:40:33 pm
content: I am out of 7805 and 7812 voltage regulators. I know a Darlington transistor connected to a voltage devidor can be used as a voltage regulator is this ok and is there anything I need to know.

author: Dave
author_rank: Super Contributor
timestamp: January 20, 2014, 06:55:38 pm
content: Just out of curiosity's sake, please draw a schematic of this solution. I REALLY want to see this.

author: electronics man
author_rank: Frequent Contributor
timestamp: January 20, 2014, 07:35:19 pm
content: sorry if the schematic isnt very good

author: madires
author_rank: Super Contributor
timestamp: January 20, 2014, 07:45:16 pm
content: Please see figure #5 athttp://www.bristolwatch.com/ele/zener_power_supply.htmfor a simple voltage regulator with a darlington BJT. Instead of the zener you could also use a TL431 with a voltage divider connected to the output.

author: electronics man
author_rank: Frequent Contributor
timestamp: January 20, 2014, 07:59:03 pm
content: I will breadboard it and give it a go.
A SIMPLE (not for me) Question about 4n25 Optoisolator!!!! - Page 1
Forum section: electronics / beginners

author: DragonSisiw
author_rank: Newbie
timestamp: September 21, 2014, 08:33:42 am
content: I am designing a circuit to control a 10W light bulb plugged in directly to 220V mains.I am going to use logic gates for my control so I will have to isolate my control circuit (with 6VDC input) from the lamp (with 220VAC).My professor ( a newbie professor, though i respect him ) said I can use 4N25 but after reviewing its datasheet, I highly doubt it will work.Datasheets say the the maximum collector current is 100mA,If P=IV then I=P/V then in my case I = 10W/220V , the current is 45mA (am i correct to assume this is OK?)BUT the problem is with the voltageDatasheets say that the collector-emitter Breakdown Voltage is 70V and 220V is too muchAny suggestions on how can i make this circuit work?Or rather can you suggest other optoisolator that can withstand a direct 220VAC connection??Thanks!!

author: Rerouter
author_rank: Super Contributor
timestamp: September 21, 2014, 08:49:30 am
content: Opto-triac, for AC stuff they are very commonly

author: tggzzz
author_rank: Super Contributor
timestamp: September 21, 2014, 09:03:28 am
content: You are correct: the optoisolator cannot directly switch the lamp.You would use the optoisolator output to control a high current, high voltage switch. Note that the initial current transient can be much higher than 45mA (e.g. in the case of a cold incandescant bulb's filament), and there might be high voltage transients due to sudden current changes in inductors.There are many examples on the web of how to do this - learning how to find such things is an essential part of engineering. (You have already done the first part: noticing that a 4N24 isn't sufficient)

author: Simon
author_rank: Unknown
timestamp: September 21, 2014, 09:28:41 am
content: opto isolators are rarely used to drive loads unless your talking a small relay or LED's, usually their job is to provide as their name suggests isolation between two sections of a circuit. You will have a low voltage and a high voltage circuit, the two will not electrically be connected but will be coupled and communicate with the optoisolator.

author: DragonSisiw
author_rank: Newbie
timestamp: September 21, 2014, 07:16:23 pm
content: Thank you very much for clearing those out for me!!Actually I already have the MOC3011 optotriac in mind and a circuit to drive my 10W light bulb, but I guess I was just being stubborn on using 4N25 because I have it ready,Guess I have to travel again to get me an optotriac or an AC relay in that case.Your help is greatly appreciated.(This is a nice blog anyway)
A simple circuit with TL081 and single supply - Page 1
Forum section: electronics / beginners

author: giorgik
author_rank: Contributor
timestamp: April 23, 2015, 07:21:02 pm
content: Hello to all you could show me a simple circuit with TL081 amplifier with single supply ?

author: Simon
author_rank: Unknown
timestamp: April 23, 2015, 07:22:42 pm
content: just google "op amp circuits"
A simple comparator circuit - Page 1
Forum section: electronics / beginners

author: elki
author_rank: Regular Contributor
timestamp: December 25, 2023, 07:34:43 pm
content: I guess there is a general issue with my approach (in the attached schematics). The idea is to generate TLL pulses if the input voltage (sine wave) exceeds a certain level. Why the output is always saturated to the rail supply?

author: wraper
author_rank: Unknown
timestamp: December 25, 2023, 07:38:20 pm
content: See input voltage range spec of LT1016

author: elki
author_rank: Regular Contributor
timestamp: December 25, 2023, 07:42:17 pm
content: Indeed!

author: elki
author_rank: Regular Contributor
timestamp: December 25, 2023, 07:43:13 pm
content: Does anyone know a fast comparator with the input voltage range from 0 to the rail?

author: elki
author_rank: Regular Contributor
timestamp: December 25, 2023, 08:06:16 pm
content: Came across AD8561 - looks like a good option. Thanks again for the quick reply!

author: shapirus
author_rank: Super Contributor
timestamp: December 25, 2023, 08:53:41 pm
content: Quote from: elki on December 25, 2023, 08:06:16 pmthere's also TLV3501, which is even faster (at 5V), but works only up to 5V.

author: Zero999
author_rank: Super Contributor
timestamp: December 25, 2023, 09:37:26 pm
content: Why does it need to be that fast? The signal in the .asc file is only 10kHz.Can't you use a -5V rail?AC couple, then the signal at the input of the comparator is centred around 2.5V. To set the threshold to 0.2V, the -input needs to be connected to 2.5 + 0.2 = 2.7V.Note, that pretty much all comparators don't work when the inputs are below the negative rail by more than 0.5V. Even if you use something like the LM393, the input will need a diode clamp to stop the input voltage going too low.

author: elki
author_rank: Regular Contributor
timestamp: December 25, 2023, 09:41:27 pm
content: Thank you. Your note about the clamping is what I have been struggling with today! Will try the approach you mention.

author: Andy Chee
author_rank: Super Contributor
timestamp: December 26, 2023, 12:08:51 am
content: Provided the input sine signal is the correct level, you can also use a 74HC14 schmitt inverter to do the job of squaring up a sine. A 555 timer can also be wired up as a schmitt trigger.Also if you're looking for similar applications, look at the people who have constructed singing tesla coils, which convert arbitrary sound waves into square switching signals:

author: Benta
author_rank: Super Contributor
timestamp: December 26, 2023, 12:59:11 am
content: Do you need a fast start-up response?If not, it's simpler to use a signal slicer. Check this app note (Fig. 4):https://www.analog.com/en/technical-articles/data-slicing-techniques-for-uhf-ask-receivers.htmlYou'll need to AC couple the input and apply a DC bias for single supply operation, but you need that anyway.

author: ledtester
author_rank: Super Contributor
timestamp: December 27, 2023, 10:52:56 pm
content: Another forum thread on the "data slicer":https://www.eevblog.com/forum/beginners/an-ldr-based-motion-sensor/
A simple homemade fan regulator - appreciate your feedback! - Page 1
Forum section: electronics / beginners

author: MatheusMM5
author_rank: Newbie
timestamp: April 10, 2020, 12:01:57 am
content: Hello everyone! I'm new here, so please bear with me.So... I've been trying to come up with a simple, yet reasonably efficient circuit for regulating the speed of a fan that can be 12V or 24V, from a 27V unregulated supply. After much banging my headI've come up with a circuit that seems to work okay... but looks a bit sketchy. What do you guys think?!Thanks a lot!

author: win22
author_rank: Newbie
timestamp: April 11, 2020, 05:47:46 pm
content: it looks fine!so wonderful!But would u like to use the power port symbol, instead the GND with red arrow?

author: MatheusMM5
author_rank: Newbie
timestamp: April 12, 2020, 03:05:30 am
content: Well, thank you! "Wonderful" was really kind of you!PSdough! That wasn't a great start, was it?! Sorry for that! That image was taken (rather lazily) from a schematic I'm drawing and botched a bit with the arrows and stuff lol. I promise I will put more effort into it next time I bring a cropped schematic here.