hybridfree/eevblog-posts huggingface dataset:
Recommended IC testers? - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: January 11, 2019, 06:41:10 am
content: Hello,I need to test some IC's like flip-flops and 32kb / 64kb RAM chips.Is something like this what i need to determine if they are problematic?https://www.amazon.com/KKmoon-MRH1631426738275XW-Multifunctional-Transistor-Capacitance/dp/B01HCXG9YS?keywords=ic+tester&qid=1547188822&sr=8-5&ref=sr_1_5Thanks in advance!

author: Brumby
author_rank: Unknown
timestamp: January 11, 2019, 08:19:08 am
content: ICs are so diverse, which means that there isn't really going to be any general purpose tester (at least not to my knowledge ... if there is, I don't expect it to be cheap and if it is cheap, I can't see it being particularly useful).The best suggestion I can offer is to make up a circuit that uses a given IC and try each chip (using a socket) to see how it operates. If you have different operating conditions, then have them set up and switch between configurations to see how it works.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 11, 2019, 08:42:15 am
content: For the logic chips, there may be some "testers", though there main purpose would be more like EPROM programming. So it more like a universal programmer for EEPROMs and the like, that can also test standard (e.g. TTL, 3 / 5 V CMOS) logic.For most other chips I am with Brumby - build a test board for that specific chip.For OPs there might be a certain sense to have one around - as they are common and relatively easy to check.For an OP I would use something like a x 100 amplifier from a switchable impedance ground. So one could test thinks like offset, bias and maybe noise, besides the basic go / no go test. It would also need a suitable supply choice (e.g. 5 V or some maybe 12 V, as some OPs are 5.5 V max. and others could be 8-10 V minimum).
Recommended relative humidity in electronic lab  - Page 1
Forum section: electronics / beginners

author: Hrvoje-CRO
author_rank: Contributor
timestamp: March 25, 2014, 03:28:55 pm
content: Hi!Well this one is relatively important thematic.What is recommended relative humidity for electronic equipment/lab/el. components?In my lab at this moment is about 50%, during summer is about 65%, even little bit more.Thank you!

author: electrolux
author_rank: Regular Contributor
timestamp: March 25, 2014, 03:33:53 pm
content: Personally I think thats perfectly fine.

author: free_electron
author_rank: Super Contributor
timestamp: March 25, 2014, 03:44:35 pm
content: the same humidity a on the calibration certificate. anything else is no-go

author: Hrvoje-CRO
author_rank: Contributor
timestamp: March 25, 2014, 06:02:08 pm
content: Quote from: free_electron on March 25, 2014, 03:44:35 pmMaybe, but that can only be possible if using dehumidifier.

author: HighVoltage
author_rank: Super Contributor
timestamp: March 25, 2014, 09:49:37 pm
content: This depends largely on what the lab requirements are and what needs to be measuredI have one customer that needs highly accurate high voltage measurements and the equipmentis located in an air conditioned room.This way, we can achieve a better than +/- 0.5 kV accuracy over a one year period of 40 kV Pk/PkAn other client does not have any control over his room temperature or humidity.Winter time down to 18°C and Summer time up to 35°CUnder these conditions, we can not even hold +/- 4 kV accuracy over a one year period of 40 kV Pk/PkSo we need to calibrate the equipment once a month or when the temperature or humidity changes big time.
Recommending Switching Power Supply Design, and (perhaps) its readers club - Page 1
Forum section: electronics / beginners

author: max.wwwang
author_rank: Frequent Contributor
timestamp: January 17, 2025, 10:46:09 pm
content: I would like to recommend the bookSwitching Power Supply Design(Pressman et al), which I recently came across when wanting to learn a bit more about SMPS, triggers by a repair project.I had a read of the chapter about the flyback topology, and it immediately let me see through the essence of it, which was extremely satisfying.Then I read the Preface written by its second author, with amusement. A read of it is recommended to all.Perhaps, if there is enough interest and like-minded people here, we can let this thread grow as a readers' club of this book, to exchange ideas, questions, insights, etc.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: January 20, 2025, 12:05:38 am
content: Now I start from the beginning of the look, hoping to have a systematic review -- but without commitment to finishing! (Too often I open too many looks and leave too many unfinished.)I now have a question about Figure 1 (attached, which is about the basis of topologies, the linear regulator). It's on p 44 of the pdf.Can someone please help me, why is there a capacitor Cf here? It looks like afull wave regulator, which does not have this. What's its function and how does it work in this circuit?

author: ledtester
author_rank: Super Contributor
timestamp: January 20, 2025, 01:22:46 am
content: It very well could be a misprint... the standard schematic is:-- taken fromhttps://www.physics-and-radio-electronics.com/electronic-devices-and-circuits/rectifier/fullwaverectifierwithfilter.htmlwhere you can also find a description of its operation.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: January 21, 2025, 08:14:35 am
content: Quote from: ledtester on January 20, 2025, 01:22:46 amThank you. That is a surprise to me, and is perhaps somehow embarrassing, because as said this is the basis (and basics) of other more advanced topologies, and yet the book does not get it right.To be sure that this is not an error (as it appears now) that only exists in the online version (as opposed to the printed book). I checked out the scanned version of its second edition onInternet Archive. It has exactly the same diagram (attached). I can't believe it.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: January 24, 2025, 10:31:58 pm
content: To my embarrassment, there is another editing error in another figure on p 51 of the pdf. The text "Error amplifier" should be placed above the symbol for the EA not PWM. Screenshot attached.Despite these issues, I'm still faithful about the quality of the book and will carry on reading.
Recommends on how to use wire up this panel - Page 1
Forum section: electronics / beginners

author: polo-mk3
author_rank: Newbie
timestamp: December 11, 2013, 10:09:54 pm
content: Hi Guys, Hope you can help me with this one and I hope I have posted this topic in the right place.I'm from the UK and have got myself an On Star panel imported from the US for my VW Passat. At the moment its fitted but all it does is illuminate with the interior lights (I wired it in to illuminate) and I would like to be able to use the 3 buttons and the 2 LED's somehow.This is the panel I have fitted:This is the board diagram/layout:I have watched Daves youtube video - EEVblog #262 - World's Simplest Soft Latching Power Switch Circuit and think this is the way forward.Would you recommend breaking the tracks and wiring 2 wires per switch to a soft latching power switch circuit or is there such a thing that can control the buttons the way that panel is designed.Its will only be used in my car to control very basic things like interior lights, reverse camera etc.I'm also looking at using mini latching relays.http://www.ebay.co.uk/itm/MINI-POWER-LATCHING-RELAY-12V-DPDT-/400609696274?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item5d4632da12I have also been told that there are mini latching buttons that will do this same thing but unable to locate anything. I have very good soldering skills and can read circuit diagrams but my imagination for circuit design is poo.Hope this all makes sense
Recommened SMT output caps for Audio DACs - Page 1
Forum section: electronics / beginners

author: hamster_nz
author_rank: Super Contributor
timestamp: October 23, 2019, 10:45:06 am
content: I'm playing around with I2S audio DACs, and noticed that across the output caps there is something small but significant non-linear going on.With probes at either end of C62 I can see that output of a saw-tooth waveform from the DAC is perfectly flat, but after the 3.3UF cap it has a bow in it.The scales are the same, there is very constant DC bias over the cap, and there is no load. I would have thought they would have tracked perfectly...What is going on?I am also pretty sure I have the wrong sort of cap - currently using some X5R 10V I had to hand. What type, hopefully in an 0805 footprint, would you recommend in the usage? I am interested to get some and see the difference.(This is just a hobby project, for my own edification, BTW).

author: ejeffrey
author_rank: Super Contributor
timestamp: October 23, 2019, 05:07:38 pm
content: Quote from: hamster_nz on October 23, 2019, 10:45:06 amI'm not sure it is strictly non-linear. There is some load from the 10 k resistors which should make a highpass filter with a time constant of 33 ms. With a 10 ms ramp time that will cause a slight bowing. I'm not sure if it is as much as you are seeing. This could be made worse if the effective capacitance is reduced due to the DC voltage offset, but I wouldn't expect this to be a problem given the presumably low DC voltage and the relatively large 0805 package size.I would try doing a distortion measurement instead of a ramp. That will tell you if you are actually seeing non-linearity or simply a low frequency rolloff. If this is just an affect of the highpass filter you can just ignore it. You might want to use a film cap instead of ceramic, but you won't get such a large value in an 0805 package. The main reason to do this is to reduce piezoelectric effects. Another option is to switch to a larger electrolytic capacitor such as a 22 uF value. A better option if you want to keep to small surface mount parts is to raise the output resistance from 10k to 100k. However once you use a load you may need an opamp buffer as the load on the other end of the cable is likely to still be on the order of 10k.

author: hamster_nz
author_rank: Super Contributor
timestamp: October 23, 2019, 06:51:19 pm
content: Oh! D'oh! It is most likely phase shift and a slight amplitude drop of the lowest frequencies I am seeing,I will make some sine signals and see what I get.

author: hamster_nz
author_rank: Super Contributor
timestamp: October 23, 2019, 11:59:00 pm
content: Took a different approach, and used Excel to see what the change in phase of the fundamental would look like.That settles it for me. It is just the the low high filter.
Recording audio with piezo contact microphones - Page 1
Forum section: electronics / beginners

author: ErnstHot
author_rank: Newbie
timestamp: March 18, 2014, 04:25:03 pm
content: I am planning to do some field recordings with a piezo contact microphone. As I understand it I need a high impedance buffer to avoid high-pass filtering, and as the sound card (http://us.focusrite.com/usb-audio-interfaces/scarlett-2i4) I will be using has phantom power (+48V) it would be nice if I could use that, rather than having to use batteries.Now, I found this circuit:http://www.jensentransformers.com/as/as004.pdfand was wondering if the part on the left of the balanced cable would work with the microphone input on the sound card?Does the circuit need some clamping so dropping the piezo doesn't fry the input of the sound card, and if I build two of the circuit how well would they match for recording in stereo?

author: fcb
author_rank: Super Contributor
timestamp: March 18, 2014, 06:18:55 pm
content: That Jensen circuit will do fine, you may want to remove the R1/C1 network though, and you probably won't need C2 either (although no harm in keeping it).You could use a balancing transformer, although I would try it first without. Just make sure you use good quality screened cable for the piezo, plenty of braided screen cover.As for protection, then probably a couple of back-back 3v3 zeners on each line would be adequate - you may not need it depending on the design of the soundcard i/p.
recovery bios from a motherboard - Page 1
Forum section: electronics / beginners

author: elettroste
author_rank: Newbie
timestamp: August 27, 2014, 09:24:49 am
content: hi i have a msi p67 gd 65(no b3) with a failed bios update.now it show the motherboard logo and restart. Can't acess to set up .I sow on the internet same programmer for 8 pin chips but can samone help me to have the right one that can i use on this bord and in ather one in the future?of course then i don't know how to extract the bios file from the .exe file.P.s: Sorry for my relay bad english

author: amyk
author_rank: Super Contributor
timestamp: August 27, 2014, 09:59:52 am
content: You need to find the SPI flash chip. It will likely be an 8-pin chip close to the southbridge; the manual may even show its location.But before trying to program it directly, check if there is a recovery mode - many BIOSes have a basic recovery in the bootblock, which will look for a file with a specific name on the root of the first floppy/USB drive and attempt to flash it. The fact that you still get a logo indicates the bootblock should be OK.Of course I am assuming you have attempted to clear the CMOS NVRAM first.

author: elettroste
author_rank: Newbie
timestamp: August 27, 2014, 12:00:30 pm
content: a)yes i tray to cean cmos and i know where the 8pin bios is.b)i tray to recover but it gave me the error :"WARNING!!!bios ME Update....FILE NOT FOUND.Please add file to your usb" if i tray to recover the bios from usb.Msi sad that is a known problem if you tray to flash the ivy bridge support bios and that the only thin to do is to san to them if is ander warrenty .1) In the msi web site there is no mention of risc 2) my board is not under warrentyc) how much can cost an spi programmer that con be support for more than 1 year and recognise future chip ?
Rectangle Connector I guess? - Page 1
Forum section: electronics / beginners

author: kb89
author_rank: Newbie
timestamp: July 20, 2014, 11:58:38 am
content: EDIT: This was an email sent to a guy, i don't think he is going to respond. So I found this website and thought it would be good to join and ask you guys.Hi, I hope I'm not bothering you or wasting your time. I am completely new to soldering, wiring, crimping, receptacles, etc... I found your site and it explains wire crimping and attaching them to rectangle receptacles which I think is going to help me a lot in this project. You explain everything in great detail and with photos which is awesome. Digging through acronyms and random forums to obtain the info I want makes me want to go crazy. Sorry about the long email. I'm just trying to get my point across.I'm gathering information on the parts that it will take for me to get a project that I want to get done. So far I have tracked down these items:24awg kynar wirehttp://www.digikey.com/product-detail/en/R24B-0100/K515-ND/80619824awg rectangle receptacle connector pinshttp://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=153906496&uq=635414289730142806a crystal oscillatorhttp://www.digikey.com/product-search/en/crystals-and-oscillators/crystals/852333?k=x100-NDa two way switch to use.http://www.digikey.com/product-search/en?KeyWords=cwi431-ndMy plan is to overclock a gameboy advance by attaching a crystal oscillator to the microprocessor (i believe). I'll be wiring microprocessor to the switch, the switch the oscillator, and the oscillator back to the microprocessor. here is a couple of pictures from the website that I got the idea from and a schematichttp://kyorune.com/modding/file.php?art=8&file=11heres the page for the projecthttp://kyorune.com/modding/article.php?id=8I'm trying to save money in shipping by ordering all of the components that I need off of Digi-Key website.So far I think I've selected the correct parts, but i'm getting stuck on what kind of rectangle receptacle I need. I think that this is the one I need 24awg receptacle here is a linkhttp://www.digikey.com/product-detail/en/643814-3/A23815-ND/289813If you notice I'm trying to duplicate this piece in the picture oscillator attached to black recepticle with wires coming outhttp://kyorune.com/modding/file.php?art=8&file=10I'm confused because the rectangle receptacle that i found on digikey, if you notice, it says it features "closed end". The picture from digikey shows holes on one end, but I don't know what is on the other end! I'm confused on if I should buy this "closed end" type (which looks a whole lot like the one he used on the mod website. Or if I should be looking at "feed through" receptacles on digikey (but they look different). Here is one that is alreadyhttps://solarbotics.com/product/14185/but I don't want that.I just want to know what part to order to connect the wires to and to also be sure I can stick the oscillator into the other side.
Rectangular PCB cutout not showing in Gerber's - Page 1
Forum section: electronics / beginners

author: FotatoPotato
author_rank: Regular Contributor
timestamp: March 09, 2019, 05:21:24 am
content: Hi all,So I'm working on a front panel for a project and I want to make it using a PCB. I finished making it in Altium and in both the 3D viewer and the built-in Gerber viewer the rectangular cutout at the top left comes out fine. (Note, you can't see the text in Altium because the layer colors are the same for some reason). But when I upload my Gerber's to JLCPCB everything except the rectangular cutout shows as you can see in the pictures that I linked. I have tried a bunch of things to solve this but nothing seems to work, even adding milling guides and cutouts don't work. Do you guys know how I can fix this?I'll link my Gerber's and all of the pictures.Thanks

author: KL27x
author_rank: Super Contributor
timestamp: March 10, 2019, 01:04:29 am
content: You might try putting this in the PCB section of the forum.I don't use Altium, but is is possible you put that rectangle in the soldermask or maybe a copper layer on accident? I notice there's no white line in the rectangle; there is a white line in all the other holes. Also, you can't mill a perfect rectangle. You need to radius the corners, and if your radius is too small, there may be an extra charge for swapping tooling.Each manufacturer has a default smallest radius they use for routing, without swapping bits to a smaller bit (which cuts slower, wears out faster, and potentially breaks more frequently).
Rectifier and Peak detector - Page 1
Forum section: electronics / beginners

author: akis
author_rank: Frequent Contributor
timestamp: May 24, 2012, 07:23:55 pm
content: I would like to construct a simple rectifier and peak detector to allow me to measure floating voltages up to +/- 100V @ 500 KHzThe requirements are as follows:1. ability to measure the peak of signals up to +/- 100 V AC2. up to 500 KHz = DC not required3. ability to work well for small signals, eg +/- 1 V and large signals eg +/- 100V.4. Ability to measure floating voltages, ie no earth connection on the probes5. Powered by a battery, so a virtual ground would be requiredMy digital multimeters work very well, but cannot handle "high" frequencies (anything over 10-20K)The oscilloscope works well, but is quite indirect (ie you have to align the curve and then try to count divisions and sub-divisions etc), plus it is grounded and makes life very difficultAn DSO would ordinarily have the value displayed on the screen, but I have not bought one yet.Initially I constructed a simple peak detector, ie a diode charging a cap and a resistor. With values of 100nF, 1M and for diode 1N4148. This works remarkably well but(a) it loads the component under test(b) the diode voltage drop error is very pronounced at small voltages, for example pct-wise, 600mV matter a lot on a 3V signal(c) the choice of diode depends on small signal accuracy vs large signal capability (eg I need to use a 1N400x when the voltage rises).Trying to improve on the above, I constructed an op-amp half-wave rectifier which will eliminate the diode voltage drop error and also provide high input impedance, for example using maybe a JFET op-amp.To solve the problem of high input voltages, I will have a switch with a fixed resistor potentiometer to do 1X, 10X, 100X, presenting a 1M resistance to the component under test (hopefully). On the diagram it shows as 10X.However the choice of the charging cap and discharge resistor is problematic, as is performance at higher frequencies (up to 500 KHz). For higher frequencies we want a small cap and large resistor (as shown), and for low frequencies we would want a larger cap.Is there a way to modify the circuit to be useable in both low and high frequencies?
rectifier question - Page 1
Forum section: electronics / beginners

author: texane
author_rank: Regular Contributor
timestamp: March 27, 2010, 12:36:44 pm
content: hi,on the following schema, I have trouble understandingwhat the d3 and d4 diode paths are used for...If I create the same schema without those paths, I getthe same voltage (I am plotting the curves with ngspiceactually) between n1 and vdd.Thus, do you have any idea what those paths are for?Cheers,t.

author: armandas
author_rank: Frequent Contributor
timestamp: March 27, 2010, 01:00:10 pm
content: Quote from: texane on March 27, 2010, 12:36:44 pmNo, unless you upload the schematic

author: texane
author_rank: Regular Contributor
timestamp: March 27, 2010, 01:08:37 pm
content: hu, sorry, a bit tired

author: armandas
author_rank: Frequent Contributor
timestamp: March 27, 2010, 01:37:39 pm
content: You need to imagine where the current flows when voltage across V1 is positive and when it's negative.In the positive cycle, current flows through D2 and D4, in the negative cycle - through D1 and D3.I'm not quite sure how it works with two diodes only

author: armandas
author_rank: Frequent Contributor
timestamp: March 27, 2010, 01:58:49 pm
content: Regarding the same voltage:I just created this circuit in LT SPICE and it seems that ground is affecting the voltage source by forcing 0V on the negative side. Check your waveforms.

author: jimmc
author_rank: Frequent Contributor
timestamp: March 27, 2010, 09:01:34 pm
content: This is the standard bridge rectifier, as armandas has implied V1 must float.D1 or D2 connect whichever end of V1 is more positive than n0 at any given instant to n0,D3 or D4 connect whichever end of V1 is more negative than Vdd at any given instant to Vdd.By the way the normal convention is Vdd is the positive rail and Vss the negative.Jim
Rectifier works!   Regulator.. iffy - Page 1
Forum section: electronics / beginners

author: iamnothim
author_rank: Regular Contributor
timestamp: March 16, 2013, 01:51:30 am
content: The rectifier works great !Thanks to David_AVD, IanB, AlfBaz, westfw, and others for your patience and ideas.I was able to get to the voltage and current I wanted using a Rescton BR31 single-phase bridge rectifier.The calculations vs. reality was within 8%. In addition I added a 65000µF "smoothing" cap.That was very cool to see on the scope, but it tacked on 1V. (Why?) I added a 2.5? resistor and bingo.I spent about 20 minutes with the voltage regulator I bought, but I didn't know what I was doing.I threw a 2.7? resistor in a loop from out to adj. It passed voltage.... but it was warming up..I will look into calculation on the adjustment circuit and see if I can make it work.I switched transformer mfg.'s from Hammond Mfg. to Triad Magnetics.Hammond was awful. I had a DOA, (no continuity on the primary) which Mouser replaced.But I sent it to Hammond anyway. They said yes it had a problem, however, "they are all tested at the factory and either Mouser or myself did something."I also asked for some info on the primary ratios when 120V is applied rather than 115V. They never answered.Triad Magneticson the other hand was amazing. I ordered a couple of their board mounted transformers from Mouser.Before they arrived I email support and asked the same question about the primaries. I said it was not a commercial applicationand that I am a retired hobbyist.Less than a day later, Jim Mettler, the Engineering Manager, wrote a one page reply with everything I needed to know.I was amazed. The transformers are compact and run very cool.Before Smoothing CapAfter Smoothing Cap 6.35V DC and .413A
Meaning of red border/markings on old Tektronix analog scopes (images included)? - Page 1
Forum section: electronics / beginners

author: SharpEars
author_rank: Unknown
timestamp: August 28, 2015, 05:18:20 pm
content: What does it mean if the 246* (e.g., 2465/2467) oscilloscope screen has a red border around it and red grid markings (silkscreen)? Is it a different (better?) type of screen than the normal black border/markings oscilloscope screen? Or is this just a cosmetic thing?I am talking about a screen like this:Notice the red border and grid around/over the screen. It is found on some models but not on others. What does it mean?

author: Andy Watson
author_rank: Super Contributor
timestamp: August 28, 2015, 05:41:40 pm
content: It means that the graticule illumination has been turned up - such that the graticule appears when you use your oscilloscope camera.

author: Electro Fan
author_rank: Super Contributor
timestamp: August 29, 2015, 02:24:46 am
content: Quote from: Andy Watson on August 28, 2015, 05:41:40 pmYep, if you turn down/off the SCALE ILLUM knob (to the left of the power button), the display will very likely turn to the standard blue color you generally see on Tektronix analog scopes. Almost any Tektronix analog scope you see that has the SCALE ILLUM knob (if it is working, which it generally will be) can be made to look like the display shown in the photo posted at the top of this thread if you turn the SCALE ILLUM knob fully up/on; by turning the knob down/off it can be made to look like the more often seen blue display. It's a standard feature - you can make most any analog Tek scope (if it has the SCALE ILLUM knob) have either appearance, and you can have a middle ground with the red graticule lines and the red border overlay plus the blue background showing at the same time. It's just a function of how far you turn the SCALE ILLUM knob. You will find the SCALE ILLUM knob on various Tektronix 22XX and 24XX models. On 7XXX models it is called the GRAT ILLUM knob.

author: Gyro
author_rank: Super Contributor
timestamp: August 29, 2015, 09:01:16 am
content: QuoteThe scope can be fitted with a clear screen filter rather than the more common blue contrast one. - many Tek scopes were originally supplied with both. Yes, turning down the graticule illumination will get rid of the red color with these, but it will still be a green trace on a light background, not blue.All filters have a black boarder that hides some of the outside visible border.I can't see a black border in the photo so it looks as if no filter is fitted. Check whether the scope does actually have a clear plastic filter fitted in front of the CRT glass, it needs to be there for implosion protection. If you prefer the traditional blue, then blue filters can be picked up on ebay or other surplus outlets (particularly in the US).P.S. Make sure you get one for the correct model (or series) as their shapes vary.
Reduce ESD  - Page 1
Forum section: electronics / beginners

author: t4rix
author_rank: Newbie
timestamp: May 24, 2014, 07:22:21 am
content: HiMy work involves building/configuring servers in a workshop type of room. I was after some advise how best to equipt the room to minimise ESD.Currently we have antistatic mats.Please advise?Many Thanks

author: t4rix
author_rank: Newbie
timestamp: May 25, 2014, 01:26:49 pm
content: Any Advise?

author: GreyWoolfe
author_rank: Unknown
timestamp: May 25, 2014, 03:06:31 pm
content: Do I assume correctly that you are using wrist straps and the mat is properly connected to mains earth? If so, that is all you really need.

author: babysitter
author_rank: Frequent Contributor
timestamp: May 25, 2014, 06:36:30 pm
content: Keep everything unrelated, especially paperm plastic packaging material and muggels, away from the workplaces!

author: theatrus
author_rank: Frequent Contributor
timestamp: May 25, 2014, 06:52:55 pm
content: And avoid any polystyrene!
Reduce inrush current LTspice simulation - Page 1
Forum section: electronics / beginners

author: rakeshm55
author_rank: Regular Contributor
timestamp: October 21, 2018, 11:07:19 am
content: I was trying to simulate inrush current for a battery powered product. Battery 28.8V li ion battery pack (10A continuous current supported...Pulse current of 18A)I use a push button controller to implement Power ON/OFF....Also a reverse voltage protection circuit ....I plan to have following sequence for input protection....Battery --->PTC ---> Transorb/MOV ----> common mode choke ----> reverse voltage protection ---> ON off controllerFor the purpose of simulation I have skipped ist three components ....On turn ON I can observe an inrush current of about 160A in simuation.... I will like to reduce is ..... Can the above circuit rearranged for soft start??Any techniques to reduce start up current...My understanding is I should keep inrush current less that pulse current of battery ... is it correct??PLease advice on methods to reduce inrush current ....

author: MiDi
author_rank: Frequent Contributor
timestamp: October 21, 2018, 09:40:11 pm
content: Inrush current limiting is achived by series resistance before caps, advanced would be ntc.Keep in mind that battery, connectors, traces/wires, components in series will all add their series resistance and the cap has esr that adds too - this is not implicitly given in simulation.As you have already a mosfet for reverse protection, you could go for one with the appropriate on resistance.Quite not shure what value is added by the mov and the common mode choke when only battery powered.

author: rakeshm55
author_rank: Regular Contributor
timestamp: October 24, 2018, 05:01:30 am
content: Can I add in some series resistance (say 10Ohms) during initial turn on??Then once the Capacitors charge to a certain voltage level say 20-22V (Use TL431) I bypass using a pmos...On googling i could not find any literature or standard technique on this --- I have seen delayed turn on but not voltage sense based Any inherent drawbacks for this??What should be wattage needed for resistor?? say I use a 10 Ohms 0.125W resistor. 100ms An average current of 1A flows. Will the resistor sustain shuch pulse loads??

author: MiDi
author_rank: Frequent Contributor
timestamp: October 24, 2018, 02:33:59 pm
content: No problem to add 10Ohms, that would give max 3A @30V.As a rule of thumb resistors can withstand 10x rated power @room temp for very short time without degrading that much.But that depends on the resistor-type, the max temperature for resistive material (not the resistor incl. case) and its thermal capacitance.In general the smaller, the less capability of short term overload.For bypassing after inrush current a pmos could fit, if a few 100mV dropout are suitable, a pnp would do it as well.You have to provide appropriate driving circuit for bypass (second inrush).
Reduce Noise ripple form Constant Current power supply. Maybe low pass filter? - Page 1
Forum section: electronics / beginners

author: wrightpt
author_rank: Newbie
timestamp: June 09, 2017, 07:44:48 pm
content: Hi,I have the following power supply: HLG-120H-350AI took it to a local tv technician to measure the noise in the circuit. He said it was around 7.2Khz. Nothing in the circuit can create noise. Just LEDs in the circuit other than the power supply.I was wondering if a low pass filter would work in dropping the noise coming from the power supply? I have not been able to find anything off the shelf that is really suited for this. I think i may be looking at it wrong.But wouldn't a low pass filter work in calming the noise? At least in theory.
Reduce Peak Voltage of a PWM Signal  - Page 1
Forum section: electronics / beginners

author: opensourcefan
author_rank: Contributor
timestamp: December 14, 2023, 06:38:37 am
content: I have a DC PWM motor speed controller with an operating voltage of 12v - 60v.However I need it to run a motor that functions best at 9.6v. The motor will pull about 1.8amps max at 9.6 volts.The motor controller doesn't play nicely with an input voltage below 12v.My initial thought was a simple 7809 circuit on the output of the controller (PWM), however I think I'd have to skip the smoothing caps and I'm not sure the 7809 could handle the PWM frequencies?Then I thought about a simple voltage divider with a couple resistors. If I'm not mistaken the max wattage dissipated would be 24w (12v x 2A) ??It's the PWM that has me bothered, not quite sure what would be best practice here.

author: Ian.M
author_rank: Super Contributor
timestamp: December 14, 2023, 06:46:57 am
content: Brushed DC motors don't really care about the peak voltage (subject to insulation limitations). Their speed is determined by the average voltage. Therefore, its likely that you all need to do is run on 12V and limit the max. PWM duty cycle to 80%, e.g. if its got a control pot wired as a potential divider, add a fixed resistor of a quarter of its value in series with the top end of its track.

author: pqass
author_rank: Super Contributor
timestamp: December 14, 2023, 06:51:24 am
content: You can connect the controller output to 100R resistor and then to the gate of a N-MOSFET like an IRF640 or better (or any other that can take the current with a max gate voltage above your controller Vcc which is usually 20V). Don't forget the flyback diode across the motor. Motor Vcc can then be different from controller Vcc.See attached. Substitute lamp for your motor.

author: opensourcefan
author_rank: Contributor
timestamp: December 14, 2023, 07:19:53 am
content: Quote from: pqass on December 14, 2023, 06:51:24 amExcellent, thank you.Will the diode create any issues when a reverse signal is sent from the controller. It has a fwd / rev switch that I need.

author: pqass
author_rank: Super Contributor
timestamp: December 14, 2023, 07:27:04 am
content: Quote from: opensourcefan on December 14, 2023, 07:19:53 amYeah, that's going to be a problem. This isn't a solution if your controller has an H-bridge (and you relying on that for reverse drive). Sorry.

author: pqass
author_rank: Super Contributor
timestamp: December 14, 2023, 07:37:00 am
content: Maybe you can just use 3, 5R resistors in parallel (a combined 1.6R) in series with the motor across controller output pins (controller Vcc=12V).R = Vdrop / I = 12V - 9.6V = 2.4V / 1.8A = 1.33R (use 3 * 5R parallel, for close enough).P = I^2R = 1.8A ^2 * 1.6R = 5.4W / 3 = 1.8W each resistor, say 5W on the safe side.
Reduce ringer volume on Commax DP-SS Intercom handset (ABSOLUTE beginner) - Page 1
Forum section: electronics / beginners

author: Ellie D
author_rank: Newbie
timestamp: December 03, 2021, 11:29:32 pm
content: Hi there, no electronics knowledge at all I'm afraid, so please frame your answers as though addressing a small spotted terrier.... I'm keen but limited. At work there's a Commax DP-SS intercom handset close to my head. I'm hoping to significantly lower the ringtone using mechanical means, i.e glue foam to a speaker or something along those lines. I opened the unit... very proud of that .... & found no discernible speaker at all. Please see pics. I don't have the knowledge to do anything fancy. if handsets come with a volume adjuster I could possibly wire that in instead. I'd also be capable of throwing the current one out the window but that's not ideal. In terms of compromise, I don't even need to be able to hear/speak to the front door guest. A quiet ringtone would prompt me to walk to the door (without even speaking to the person). Any dumbed down assistance much appreciated. Thank you

author: Ellie D
author_rank: Newbie
timestamp: December 03, 2021, 11:32:52 pm
content: Seems like initial post didn't accept both images so I'm attaching again here. Thnx

author: 妖怪女
author_rank: Newbie
timestamp: December 05, 2021, 06:03:50 am
content: That's weird. I looked at a picture of the model. What is on the other side of the base? (the cover) I see the speaker hole pattern in a picture. There is no speaker there?If not, try taping the hang-up button down, and move the handset a few feet from the base and then have somebody ring the bell and see if the sound is actually coming from the handset.

author: Rmen
author_rank: Newbie
timestamp: February 21, 2024, 05:58:29 am
content: HelloPlease make photo from back of PCB that show all wire track very clear and send.I think sound generat out side of this device.so after re engg shematic diagram it is possible better help.RegardsRmen
Reduce rumble vibration - Page 1
Forum section: electronics / beginners

author: Erwin Ried
author_rank: Regular Contributor
timestamp: March 06, 2014, 07:17:58 am
content: I have a little wireless keyboard that I use with a raspberry pi, the keyboard is nice but it has an annoying noisy vibration.How to reduce that vibration? simple resistor should work?

author: valentinc
author_rank: Regular Contributor
timestamp: March 06, 2014, 12:39:21 pm
content: What are you reffering to ? A mechanical vibration ? I don't understand... Please explain...

author: Erwin Ried
author_rank: Regular Contributor
timestamp: March 06, 2014, 04:38:57 pm
content: Yes, sorry a tiny small motor with a weight, but it rumbles too strong

author: valentinc
author_rank: Regular Contributor
timestamp: March 06, 2014, 07:49:24 pm
content: The motor is inside the keyboard as feedback when you press a key ? Or commanded by the raspberry pi ?If the power consumption of the motor is not high (and I guess it shouldn't be if it's one like those used in mobile phone) a simple series resistor will work...

author: Erwin Ried
author_rank: Regular Contributor
timestamp: March 06, 2014, 08:10:28 pm
content: Yeah it is a small mobile vibration motor. I will try with a resistor

author: qno
author_rank: Frequent Contributor
timestamp: March 07, 2014, 11:23:01 am
content: What type model maker is it.I can imagine, to save batteries, there is an option to switch it off

author: XOIIO
author_rank: Super Contributor
timestamp: March 07, 2014, 12:17:40 pm
content: You could just disconnect it if you don't want it on at all, or measure the current/voltage it uses with a multimeter and find the resistor you would need o reduce it by half.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: March 07, 2014, 11:04:19 pm
content: http://www.amazon.com/LOFREE-2-4GHz-Wireless-Keyboard-Windows/dp/B00EOFFO26this is the keyboard.Almost all the reviews in different places tell about the annoying vibration. It is useful, but it is so strong! It was pretty easy to disassemble but there was an extra screw below the acrylic surface, so it is impossible to do without denting the plastic. I also broke the small smd switch used to switch mouse/keyboard, but I had a similar switch (a bit higher, but solved cutting part of the plastic button).Tested some resistors and a 100 ohm one leaves the device with a smooth almost invisible rumble, perfect as tactic feedback.
Reduce the thump sound from a analog drum circuit - Page 1
Forum section: electronics / beginners

author: nathanpc
author_rank: Unknown
timestamp: June 05, 2016, 07:17:29 pm
content: I've been thinking about building a drum machine for quite some time. To start things out I decided to look for some of the basic circuits that are required for it, so I stumbled acrossthis circuitand decided to try it out. It does produce a very convincing sound. This is the circuit I've prototyped on a breadboard:The only difference is that I'm using a LM358 opamp and the input is a push button with a 10k resistor to ground and a 10k resistor to the 9V rail, but I'm having a bit of a problem (or maybe the circuit is supposed to be like this and I'm just being dumb), as you can see are are two very loud thump sounds when I press the button and when I release it, what can I do to remove, reduce or improve the circuit to have a better drum sound?

author: sync
author_rank: Frequent Contributor
timestamp: June 05, 2016, 07:57:57 pm
content: You need a short pulse on the input. Maybe 1ms. When using a single supply the input should be about V+/2 with the short pulse to V+ or ground.

author: nathanpc
author_rank: Unknown
timestamp: June 05, 2016, 08:46:36 pm
content: Oh! Thanks very much sync! That solved the problem it's now working great!

author: Zero999
author_rank: Super Contributor
timestamp: June 05, 2016, 09:00:24 pm
content: Yes, you were saturating the op-amp too.How are you generating the short pulse? You could try a piezo transducer or a monotstable+ switch.The LM358 isn't the best opamp for this because it suffers from crossover distortion.

author: nathanpc
author_rank: Unknown
timestamp: June 05, 2016, 09:08:20 pm
content: Hero999, for now I'm using a PIC with a super simple program to turn on a MOSFET for about 1ms when I hit a switch, but the finished project will be controlled all from 7400/4000-series logic and a huge amount of switches.I'm using the LM358 just because it was the first thing I saw on my bench haha, in the final design I'll probably use the LM833 since I have a massive amount of them.

author: sync
author_rank: Frequent Contributor
timestamp: June 05, 2016, 10:29:05 pm
content: Btw: the real 808 drum voices using more complex circuits. For example the base drum. TRIG is the trigger shared with all voices. It's a positive pulse. When an accent is played the amplitude of TRIG is higher. BD selects the base drum. See the TR-808 service manual for more information.

author: amyk
author_rank: Super Contributor
timestamp: June 06, 2016, 04:26:08 am
content: I thought drums were supposed to make a "thump" sound.
Reducing standby current and battery protection - Page 1
Forum section: electronics / beginners

author: smackaay
author_rank: Regular Contributor
timestamp: November 29, 2012, 09:20:44 pm
content: I was curious if anyone had a simple to implent method of reducing standby current to a device and to protect a LiPo battery from draining completely. Let me describe the device. The device draws about 350 mA during use but I want to have a soft on-off as well as a timer off so that the device shuts itself off when it's not being used. The device is powered from a 850mah 7.4V battery and it goes to an on-board 5V switching regulator.Does anyone know of a way to protect the battery from draining below 6v and also allowing a low current (or none) with a soft on-off-sleep? this device is going to be used sporadically so if the battery is dead all the time, that'd suck.Any help would be appreciated.

author: M. András
author_rank: Super Contributor
timestamp: November 29, 2012, 09:33:28 pm
content: set the undervoltage lockout to 6v on the switching regulator? im not sure how much current would it need when in this mode never checked any of them

author: Simon
author_rank: Unknown
timestamp: November 29, 2012, 10:35:29 pm
content: would a comparator use a small enough current ?, you need some standby current, what is the acceptable limit ?

author: nukie
author_rank: Frequent Contributor
timestamp: November 29, 2012, 11:03:17 pm
content: Seiko makes a lot of lithium protection IC and if they are too expensive, then the Chinese copies works okay too, but they draw too much current sometimes.

author: smackaay
author_rank: Regular Contributor
timestamp: November 30, 2012, 12:56:50 am
content: Hmmm, I'm going to see if there's an IC that can do the battery protection. As for the software on-off... hmmm

author: AlfBaz
author_rank: Super Contributor
timestamp: November 30, 2012, 01:34:08 am
content: Are you able to obtain the specs for the battery? Normaly they have built in protection for over-voltage and temperature it may also shut itself down at a certain voltage

author: smackaay
author_rank: Regular Contributor
timestamp: December 01, 2012, 01:42:48 am
content: I was just going to use an RC battery. There is no thermistor or voltage protection.
Reducing Voltage for internal RTC - Page 1
Forum section: electronics / beginners

author: FelixK
author_rank: Contributor
timestamp: March 24, 2015, 10:13:13 pm
content: Hi,I've been building some projects using the Arm M0+ KL25z micro controller family on the mbed platform. I'm looking to upgrade to STmicro'sSTM32F401chipset. I've been using an external real time clock on the KL25z and I've noticed that the STM32F4 family has one that is built in. For this to work I need to connect the STM32F4's Vbat pin to battery so when my regulator is switched off, the RTC still would be powered. The STM32F4's VBAT can be powered with voltage source of 1.65 to 3.6 V, however theLiPo batteriesI've been using output a maximum of 3.7V and charging cutoff at 4.2V.What would be a reliable way to power the RTC? Would a simple voltage divider or diode be sufficient?Thanks!
Redundant Power ORing - Page 1
Forum section: electronics / beginners

author: Darlington
author_rank: Contributor
timestamp: April 22, 2024, 12:12:58 pm
content: Hello everyone,I was designing a redundant power supply circuit and was looking for ICs to perform this task, such as LTC4358. Unfortunately, it is really expensive if good.Does anyone know of a low cost equivalent that performs the same function?It must be able to work at a voltage of 12v on a 4/5A load.

author: aliarifat794
author_rank: Regular Contributor
timestamp: April 22, 2024, 12:25:55 pm
content: Texas Instruments TPS2490 can be an alternative.https://www.ti.com/product/TPS2490
refence input impedance on counter  - Page 1
Forum section: electronics / beginners

author: TX5Z
author_rank: Newbie
timestamp: May 07, 2024, 07:43:10 pm
content: Howdy,Curious about the reference input impedance on a couple of counters - 500 ohms and >100K ohms. (HP 5316B and TTI TF930)My reference output is 50 ohms.1. Should / could I use a 50 ohm terminator on the reference input?2. If I used a 50 ohm terminator, how would the input limits change? The 500 ohm input is 6Vrms max, if using a 50 ohm terminator it is now ____?3. In general, does using a 50 ohm terminator on 500 ohm or 100K ohm input give the same results as using a 50 ohm terminator on a 1M ohm input (like a scope)?I did search, and search and found much info on 50 ohm terminators - but couldn't find the above info.MANY THANKS!

author: wasedadoc
author_rank: Super Contributor
timestamp: May 07, 2024, 07:54:57 pm
content: Quote from: TX5Z on May 07, 2024, 07:43:10 pmYou can use a term on the counter input but depending on the reference frequency and the cable length between ref gen and counter it may not be necessary.Adding a term does not affect the input limits of the counter's ref input per se. It does affect the amplitude fed into it. It is almost halved. Basic voltage divider stuff. Source contains 50 Ohm series resistor. Load is 50 Ohm term in parallel with counter ref input impedance.

author: bdunham7
author_rank: Super Contributor
timestamp: May 07, 2024, 07:56:08 pm
content: Quote from: TX5Z on May 07, 2024, 07:43:10 pm1. No, not usually unless your cable from the reference to the counter was very long (like 5 meters or more) and even then probably not.2. The voltage limits wouldn't change at all since the 50R terminator is across the inputs. However, you'd have to consider the limits of the terminator itself and the effect on the output of the reference.3. On the 100K input you'll end up with a total load of approximately 50R, but with the 500R input, you'll get ~45R combined, so not perfect. It still probably won't matter at all.I have an HP 5316B and I've never once worried about this issue.

author: CaptDon
author_rank: Super Contributor
timestamp: May 07, 2024, 08:19:22 pm
content: The worst that could happen is reflections which if big enough in amplitude could make your counter think it had a 20MHz input when in fact you were feeding 10MHz from your frequency standard into your counter's reference input. And only about a .01% chance anyone has ever had that issue!!