hybridfree/eevblog-posts huggingface dataset:
Choosing a Hall Effect Sensor - Page 1
Forum section: electronics / beginners

author: aussieW
author_rank: Newbie
timestamp: April 26, 2021, 09:14:19 am
content: HiI am trying to choose a cheap hall effect sensor for use in a project. I'm looking for an omnipolar, non-latching switch with hysteresis. I found this sensor HMX3033H (Datasheethttp://anasemi.com/pdf/PDF13.pdf) which appears to satisfy my requirements but the datasheet doesn't actually use the words I was looking for in my requirements. Can anyone reassure me that it is a good selection.Many ThanksaussieW

author: ledtester
author_rank: Super Contributor
timestamp: April 26, 2021, 09:56:29 am
content: Well, it says it's a "Omnipolar Hall Effect Switch" on the second page.And on page 5 it says the "Width of hysteresis" is 0.5 mT.Also on that page the "Magnetic-Electric Conversion Characteristic" graph shows the standard hysteresis behavior.On page 6 the "OUTPUT SWITCHING TIMING CHART" gives an example of how the output changes with the magnetic flux.

author: aussieW
author_rank: Newbie
timestamp: April 26, 2021, 10:05:59 am
content: Hmm, maybe I should have done a search rather than rely on my poor reading skills

author: aussieW
author_rank: Newbie
timestamp: April 26, 2021, 10:22:33 am
content: If it is an omnipolar sensor does that automatically imply that it is non-latching?

author: ebastler
author_rank: Super Contributor
timestamp: April 26, 2021, 11:59:04 am
content: Quote from: aussieW on April 26, 2021, 10:22:33 amWhy would those two properties be related?The block diagram on page 4 shows a dedicated latch circuit, which seems quite independent of the actual sensor.

author: ledtester
author_rank: Super Contributor
timestamp: April 26, 2021, 02:03:28 pm
content: Quote from: ebastler on April 26, 2021, 11:59:04 am"Latching" for a Hall effect sensor means the opposite polarity is needed to change the output:https://sensorso.com/hl.htmlThe term "latch" in the above datasheet refers to when the output for a sampling period is determined.I believe omnipolar implies non-latching as the output is determined by the absolute value of the magnetic flux -- i.e. its strength -- and not its polarity as shown by the Switching Timing Chart.This video (starting at 5:30) demonstrates that the A3144 Hall effect sensor is a uni-polar non-latching device:https://youtu.be/hV8mqPxEAUY?t=5m30s

author: ebastler
author_rank: Super Contributor
timestamp: April 26, 2021, 02:54:02 pm
content: Thanks, ledtester -- I was not aware that this persistence of the Hall effect went by "latching" too. And that datasheet did its best to confuse me...Allegro seems to imply that omnipolar Hall switches can be (or always are?) also latching. Or are they talking about electronic latches again?Quotehttps://www.allegromicro.com/en/insights-and-innovations/technical-documents/hall-effect-sensor-ic-publications/omnipolar-switch-hall-effect-ic-basics
Choosing a power supplies for a 3D printer Project - Page 1
Forum section: electronics / beginners

author: WAmaker
author_rank: Newbie
timestamp: April 23, 2013, 02:21:18 am
content: Hi,The electronics for my 3D Printer Project needs a 12v 15A supply (electronics) and a 24V 10A (for the heater bed). I have searched for a dual output unit (240VAC input required) but can't seem to find anything to fit my requirements.Any suggestions for this problem?? I would prefer one unit but if I have to use two that will be OK.Thanks from a newbie to this game.

author: rentner
author_rank: Regular Contributor
timestamp: April 23, 2013, 08:42:37 am
content: It would propably be cheap, If you use PC Power supplies. (ATX) They handle the current. How to get 24V? Well, you have to put them in series. This is definitely possible, but will be not easy and not safe, if the unit fails, because you have to set the mains ground 12V higher, because Ground ist overall Mains ground in those supplies. Play safe only! Do it, if you know about such things. A PC Supply is cheap, no more than 20$ - total of 40$. But you know, what I told you about safety with "floating" Earth Grounds.Good luck.

author: Balaur
author_rank: Unknown
timestamp: April 23, 2013, 08:58:00 am
content: I had a quick look at theMean Wellpower supplies. It looks to be difficult to find a single power source delivering the power/voltages you need.If you can go for a dual setup, I would recommend either a PC (or a XBOX 360 - very good suggestion frompeter.mitchell) PSU for the 12V and other supply (example:Mean Well NES-350-24) for the 24V

author: Rerouter
author_rank: Super Contributor
timestamp: April 23, 2013, 09:12:15 am
content: atx power supply capable of 35A on 12V (not to uncommon though may need to reconnect the feedback wire to the 12V rail through a voltage divider for stability)and use a standard automotive 10A 12-24V inverter,

author: amyk
author_rank: Super Contributor
timestamp: April 23, 2013, 09:33:34 am
content: It looks like you need 420W of power, which a PC PSU could easily do.Is it possible to change the heater to a 12V 20A unit instead? If you could do that then you just need 35A at 12V, which could be easier to find than 2 voltages.

author: GeoffS
author_rank: Unknown
timestamp: April 23, 2013, 11:03:13 am
content: That's quite a high power requirement for the heated bed.My 3D printer only requires 8.5A @ 12V for the heated bed. Not sure what the electronics takes.It was supplied with a single 12V, 30A power supply (Meanwell)

author: WAmaker
author_rank: Newbie
timestamp: April 23, 2013, 11:57:34 pm
content: Thanks for all the ideas, I should have given a little more background......The board I am using is a Megatronics V2.0 which will handle the 2 voltages. I have also chosen to go down the 24V heater bed path to give me a shorter heat up time. The reason why we have the high amps is that the bed size is 300mm x 300mm.An additional though... what if I go for a 24V supply with multiple outlets, can I reduce one of these to 12V? If so what needs to be done?Andrew
Choosing a radiator depth.  - Page 1
Forum section: electronics / beginners

author: Fflint
author_rank: Frequent Contributor
timestamp: April 22, 2025, 03:17:50 pm
content: I'm repurposing a bunch of old CDMA cell tower amplifiers. They come on a pcb that is roughly 120mm x 180mm. They are 50W and 50% efficient. Most of amplifying is done by 3 bjt transistors. A 10W a 25W and a 50W. The amp will be run under it's target voltage at 18V and it will consume up to 5A of current. (so 90W). The radiator has to be as big as the pcb with a couple slots milled for protrusions.But the depth or the thickness is to be decided.There are these "radiators" that are just a piece of aluminium extrusion. There are also ones that are very thick. Which one should I use? %202003-2006

author: xvr
author_rank: Frequent Contributor
timestamp: April 23, 2025, 01:20:12 pm
content: Something like this -https://www.bedbathandbeyond.com/Home-Garden/Slotted-Notch-Aluminum-Heatsink-Adhesive-Conductive-Thermal-Pad-3D-Printers-4Pcs-Black-25x25x10mm/40046243/product.html?option=81958282

author: Fflint
author_rank: Frequent Contributor
timestamp: April 25, 2025, 10:47:13 am
content: Quote from: xvr on April 23, 2025, 01:20:12 pmThis is tiny... Perhaps it would be fine, but I'm also thinking to use the radiators as a support structure.Here is the pcb front and back:As you can see there are some protrusions in the back. We have two of what looks like brass heat spreaders and some through hole pins.I've bought these radiators cheaply:They are the size of the pcb and 25mm thick. I was planning to mill slots for the through hole parts, but it seems a waste of time to be milling slots for these heat spreaders.I'm thinking about simply desoldering them. But then the surface will be bad unless I remove every last trace of solder. Alternatively maybe adding some pad between the radiator and the pcb would be a good idea. So the spreaders can rest on the radiator and the pcb on the pad...Thermal pads that size will not be cheap probably.What do you think ?
choosing a reverse protection diode  - Page 1
Forum section: electronics / beginners

author: anishkgt
author_rank: Frequent Contributor
timestamp: January 08, 2018, 08:14:09 pm
content: hi All,I have a Constant current source used for powering a servo 7v 3A and wish to protect it against reverse polarity. What would be the specs that i should be looking for.I went though DigiKey and if am not wrong are standard rectifier ideal for this application ?Thanks in advance.

author: Signal32
author_rank: Frequent Contributor
timestamp: January 08, 2018, 10:40:31 pm
content: You probably don't want to use a diode with such high currents, you will loose a lot of power and generate a lots of heat in the diode.Use a MOSFET:http://www.ti.com/lit/an/slva139/slva139.pdf

author: David Hess
author_rank: Super Contributor
timestamp: January 09, 2018, 01:40:57 am
content: If the reverse voltage is moderate, then a schottky rectifier will have about half of the loss making it more acceptable. Even with significantly derating, a schottky rectifier will be inexpensive.

author: anishkgt
author_rank: Frequent Contributor
timestamp: January 09, 2018, 03:56:47 am
content: So would something like a schottky above 3A be ok say about 5A ?Www.Georgehobby.wordpress.comEquipments: DSO104z, Hakko FX888D, Brymen BM869s

author: David Hess
author_rank: Super Contributor
timestamp: January 10, 2018, 04:39:43 am
content: Quote from: anishkgt on January 09, 2018, 03:56:47 amI do not quite understand what you are asking. The average and peak current ratings for the diode should exceed the average and peak currents that you expect in the circuit. This should not be a problem as currents higher than 5 amps are available inexpensively even in small packages.

author: anishkgt
author_rank: Frequent Contributor
timestamp: January 10, 2018, 04:42:22 am
content: The stall amp of the servo is 3A and normal working is 1 to 1.5A. So I guess 5A has enough room.Www.Georgehobby.wordpress.comEquipments: DSO104z, Hakko FX888D, Brymen BM869s

author: anishkgt
author_rank: Frequent Contributor
timestamp: January 10, 2018, 04:43:30 am
content: Secondly can these be placed on the negative side also or should it be in positive voltage to the load.Www.Georgehobby.wordpress.comEquipments: DSO104z, Hakko FX888D, Brymen BM869s

author: David Hess
author_rank: Super Contributor
timestamp: January 10, 2018, 01:55:34 pm
content: Quote from: anishkgt on January 10, 2018, 04:43:30 amThat depends on the signaling requirements and whether a positive or negative signal common is used. Vehicles for instance use a negative ground so reverse protection goes on the positive side.

author: anishkgt
author_rank: Frequent Contributor
timestamp: January 10, 2018, 03:54:52 pm
content: Thank you David. The servo is controlled via an arduino for a project and the GND is common. Here i am using the Constant Current source which needs to protect by the diode agains reverse polarity.
Choosing a Switchmode Converter for a Battery Powered Project - Page 1
Forum section: electronics / beginners

author: nathanpc
author_rank: Unknown
timestamp: July 15, 2013, 01:42:02 am
content: I'm currently designing a battery powered, 2xAA in this case, project. The problem that I have is very simple, I want to power aDS1307(the only part in my circuit which requires 5V). I've looked into similar parts like theDS1337and theMCP7940, which operate under 3V, but they don't have a battery backup pin like the DS1307, which is something I want.So, the first thing that I thought was to build a step-up DC/DC converter circuit to power the RTC (that's the first thing I thought, so I'm open for suggestions). Since I never used a switchmode converter before I decided to watch Dave's video about theMC34063:But the problem with it IC is that its minimum input voltage is 3V. So I would like to know some tips on how to choose a suitable switchmode converter for this kind of project.

author: mariush
author_rank: Super Contributor
timestamp: July 15, 2013, 03:46:08 am
content: There are plenty of boost converters, it's enough to just go on digikey.com and play with the filters, for example here's some suggestions :http://goo.gl/0THCBBut the power consumption of that ds1307 is low enough that you may get away with a voltage doubler/tripler and then getting it stable with a low drop linear regulator like mcp1801, mcp1702 etc .Dave did a video on voltage doublers just a few weeks ago if I remember correctly.

author: lgbeno
author_rank: Frequent Contributor
timestamp: July 15, 2013, 04:52:56 am
content: Is it always powered from batteries or are there also time when it is wall powered? If always from battery, I don't see much advantage in requiring the vbatt pin. I would consider selecting something operating at a lower voltage if possible.As far as boost converters, look at Semtech SC120, very easy to use (just copy the application circuit in the datasheet). It has decent Iq and low Vin.Personally I prefer using a low, single alkaline cell so that the PS is always a boost configuration over the voltage range of the battery. (Assuming mostly 3.3v circuits. For 2 cells there is an interesting boost converter from TI that is a boost but also does some step down conversion for fresh batteries. Part number escapes me at the moment...Voltage multipliers work but they don't have very great efficiently. They also don't regulate voltage so you would end up with more loss in the circuit for regulation.I have been doing an experiment with SC120 where I'm powering a Hall effect sensor with the SC120 and a single AAA battery, it's been running non stop since march and still works like a charm.

author: AndyC_772
author_rank: Super Contributor
timestamp: July 15, 2013, 07:41:01 am
content: Use a DS1338-18? It has a separate VBAT supply and works down to 1.8V.http://www.maximintegrated.com/datasheet/index.mvp/id/3696
choosing audio amplifier IC - Page 1
Forum section: electronics / beginners

author: 4a4ik
author_rank: Contributor
timestamp: June 03, 2016, 07:30:46 am
content: Hello, How would you choose an IC if you need to build an audio amplifier ?I usually used something popular like tda2030, but are there company catalog of some sort, where I can find all the IC's that company has produced with all the specs ?For example I tried st microelectronics and Maxim sites to find this info, but I could only find their last 20 Ic's.Where or how I need o search, to find an audio amplifier IC that suits my requirements ?Just in general, I don't need a specific IC right now.

author: danadak
author_rank: Super Contributor
timestamp: June 03, 2016, 09:41:15 am
content: There are selector tools here -http://www.ti.com/lsds/ti/analog/audio/overview.pageRegards, Dana.

author: Unknown
author_rank: Unknown
timestamp: June 03, 2016, 02:19:52 pm
content: If you are just looking in general, you could try using one of the distributor websites like Digikey / Element 14 etc. They have parametric search options which may be helpful in narrowing down your choices.
Choosing coaxial cable for home made Function Gen. and/or Oscilloscope cables - Page 1
Forum section: electronics / beginners

author: nour
author_rank: Frequent Contributor
timestamp: October 26, 2016, 12:24:26 pm
content: I want to make my own custom-length coaxial cables for my Function Gen.\ Oscilloscope so I decided to buy a around 5 meter of coaxial and some BNCs to do itI started herehttp://www.tme.eu/en/katalog/coaxial-cables_100157/Basically there is a lot of variations that confuses me.I have narrowed down the search by selecting only 50 ohm impedance and of course rejected any minimum quantity more than 5+So I ended up with few and choosed this onehttp://www.tme.eu/en/details/rg316_u/coaxial-cables/helukabel/40203/The basic usage will not involve more than 100-150 MHZ at most of the time and may be I will use it as 2.4GHZ antenna extension cable! and also I want the cable to be flexible as possible (Min. bending radius)So what do you think about it and what should I care about when choosing this kind of coaxial cables?

author: nour
author_rank: Frequent Contributor
timestamp: October 27, 2016, 12:23:18 am
content: Did I wrote the topic in the wrong section !!It seems like it should have been in the test equipment section!

author: rs20
author_rank: Super Contributor
timestamp: October 27, 2016, 12:41:44 am
content: I was a little bewildered by the amount of choice when I went down this road as well, so you're not alone! Having said that, if you're mostly working down at only 100-150 MHz, just about anything will do. RG-58 and RG-316 (what you linked) are very popular and widely available choices, so I expect you won't have much trouble finding connectors to suit either. RG-58 has somewhat lower attenuation per meter than RG-316*, but RG-316 is much more flexible. So given your stated desire for flexible cable, and then relatively undemanding electrical nature of your requirements, I'd say that the RG-316 cable you selected is near-ideal.Make sure that the plugs you buy are suited to the cable you get! There's no such thing as a universal BNC connector, there are BNC connectorsfor RG-58and BNC connectorsfor RG-316. Make sure you can find suppliers for appropriate BNC/SMA/RP-SMA connector for your chosen cable before committing to the cable.* Seethis enormous table of figures. In short, up around 2.4-3 GHz, a 60 cm length of RG-316 will have about the same attenuation as RG-58.
Choosing components for a circuit - Page 1
Forum section: electronics / beginners

author: Rigolon
author_rank: Regular Contributor
timestamp: October 30, 2017, 03:53:15 pm
content: Hello all,Quick question, when designing a circuit should I choose the components by the peak value (voltage/current) or by the rms value?For example, to calculate the resistor power rating which variables do i use?

author: xani
author_rank: Frequent Contributor
timestamp: October 30, 2017, 05:10:53 pm
content: Depends on component type, size and duration of the peak. Also, look at the datasheet, some values will have both specifiedFor example, putting 2W on 0.5 W resistor for 2ms will most likely be fine. But overvolting a MOSFET gate will probably break it. But on the other side MOSFETs usually have continuous and pulsed current specified in datasheet.Also in some cases getting close to max values might affect longevity of the product so doing stuff like putting 12V-rated +70C cap on 12V line with 60C ambient temp is probably a really bad ideaI generally err on side of caution if possible.

author: sokoloff
author_rank: Super Contributor
timestamp: October 30, 2017, 05:37:49 pm
content: Resistor power rating would be by RMS. Heat sinks you would size by RMS (for the same reason).This assumes a typical AC frequency. If you take the AC frequency down to 1 cycle per 5 minutes or longer, you can't do this anymore.

author: TimFox
author_rank: Super Contributor
timestamp: October 30, 2017, 07:27:50 pm
content: Note that when you speak of power in a resistor, it ismean power, notRMS power. The mean power is the square of the (RMS voltage) divided by the resistance, but that does not give RMS power.
Choosing connectors and crimping tools (around 3A) - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: April 14, 2020, 04:11:26 pm
content: Hi,normally I do not need much amp for my board-to-board connections, so I use mainly 22AWG stranded wires, and to connect them I use either dupont connectors withthiscrimper, or someJST-XH, crimped with the wonderfulengineer PA-09crimping tool.Now I need something beefier for a new project which will have to withstand ≈3A for a few seconds at a time. My puny cables do not give me confidence, so I think to switch to at least 20AWG or 18AWG.I like the locking style of the jst connectors, but the sea of connectors is immense and I don't know which one to choose. I'd like something that will be either crimpable with my tools or with a tool that will cost 50€ max.Can you please help me? I hope I posed the question in an understandable fashion.

author: Monkeh
author_rank: Super Contributor
timestamp: April 14, 2020, 04:14:34 pm
content: Just keep using what you have. 3A is nothing, and you want seconds, which is.. also nothing. There's no need to change connector or wire size.

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 15, 2020, 08:07:48 pm
content: 22 AWG is ok for short 3A, and connector too, I agree.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: April 16, 2020, 03:12:04 am
content: If you're really worried, do a voltage drop measurement on your wire, and make sure you're not dropping too much.

author: Jwillis
author_rank: Super Contributor
timestamp: April 16, 2020, 03:46:54 am
content: The 22 AWG is good for 3amps @ 60Cobut can go as high as 7 Amps @ 75Co. These are maximum ratings as defined by the National Electrical Codes and depends on the type of covering on the wire.If an increase in plug size is not an issue then you could shift to the JST-VH series. Only thing is they have a 3.96mm pin spacing but have a 10 A AC/DC Rating and can take AWG #16 wire.Another option is the JST-XA series, They will take AWG #20 which would be more than plenty for your needs.

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 16, 2020, 07:42:12 am
content: One may parallel connector contacts (use 2 contacts for 1 wire, so 4 for 2 wires) if there is any worry - it will be smaller size then larger type (4 mm) connector. It is a usual industrial trick.
choosing led driver - Page 1
Forum section: electronics / beginners

author: seasider
author_rank: Newbie
timestamp: December 09, 2018, 02:00:10 am
content: Hello all,I have 5m of 12v 3528 led strip lighting. I would like to get the proper driver for it. From what I have found so far, this 3528 strip uses .4a/m and the driver should run at 80% of total capacity so a 3a driver should work since the 5m strip will draw 2a. The led strip needs to be installed 15 feet from the driver . I can't find any info. on the driver size and wire size for this run. Any solutions greatly appreciated

author: Jwillis
author_rank: Super Contributor
timestamp: December 10, 2018, 01:22:09 am
content: Your Led strip will only draw as much current as it requires at a set voltage so if your strip is rated for 2 amps at 12 volts then a 12v 3 amp driver would work.Personally I would double your required current to 4 amps. The resistance of the wire will very with gauge ,length and material . So 15 feet of 18 gauge copper wire will have around 0.096 ohms .That will produce around 0.38 watts.Not very much.Whether it's solid or stranded it really won't make much difference so here's a chart that may help

author: kjr18
author_rank: Regular Contributor
timestamp: December 10, 2018, 12:37:54 pm
content: If power supply will be 15 feet away, you will have 30 feet total, so your led strip voltage will be lower, voltage dropped will be around 0.7V. Thicker wires will result in lower drop. You could also try to get a power supply with some output regulation, I don't know if branded ones have something like that, but most of the chinese power supplies have a small pot near output terminals.

author: seasider
author_rank: Newbie
timestamp: December 11, 2018, 09:25:49 pm
content: Thanks for the info. I think this one will work. The led strip will be connected to a dimmer so hopefully this type of driver will work with the 50% load it will receive.

author: seasider
author_rank: Newbie
timestamp: December 11, 2018, 09:28:20 pm
content: The driver is 12v 4.2a 50w

author: Jwillis
author_rank: Super Contributor
timestamp: December 11, 2018, 10:42:21 pm
content: I think that should be fine. With 18 Gauge wire ,the negative and positive lines will dissipate the nominal heat interdependently.And to reduce any Electromagnetic interference twist the wires together.If anyone can add or correct something I missed feel free to comment .
Choosing Parts with spice characteristic - Page 1
Forum section: electronics / beginners

author: igorbog
author_rank: Contributor
timestamp: October 31, 2011, 08:57:50 pm
content: HiI am a newbie and I have a question.if I want to build for example oscillator based on opamp. How should I choose parts and where I can get their Pspice models.THanks

author: Simon
author_rank: Unknown
timestamp: October 31, 2011, 09:41:16 pm
content: the manufacturers website will often supply the model, or it may already be in the software you are susing if it is a well known and used part

author: w2aew
author_rank: Super Contributor
timestamp: November 01, 2011, 02:36:36 am
content: Quote from: igorbog on October 31, 2011, 08:57:50 pmThe choice of which part to use for an application will depend entirely on what your requirements are. You'll have to ask yourself some questions like: What power supply voltage (or voltages) are going to be used? Does the output need to swing to both supply rails or not? Do the inputs need to be able to go to the supply rails? How fast does the circuit have to be? What kind of supply current can I afford for the opamp? What kind of load is it going to drive? How noisy can the output be? What kind of gain do I need (and still have it be stable)? How much precision is needed? etc.Without answering at least some of those questions, you can't begin to narrow down a particular opamp.

author: igorbog
author_rank: Contributor
timestamp: November 01, 2011, 06:22:32 am
content: And after I choose the parts Does the company of the parts should give me the spice model?

author: Bored@Work
author_rank: Super Contributor
timestamp: November 01, 2011, 07:48:08 am
content: Quote from: igorbog on November 01, 2011, 06:22:32 amSome do, some don't.But I recommend you give up your obsession with SPICE. SPICE is an analysis, not a synthesis tool. It will not magically design your circuit. You alone have to do this.
choosing passives for dc - dc regulator - Page 1
Forum section: electronics / beginners

author: aaronhance
author_rank: Regular Contributor
timestamp: October 05, 2016, 06:48:27 pm
content: Hello again! I'm working on a schematic and I'm currently working on laying out a DC - DC regulator the TL2575-33IKTTR. I'm a hobbyist so I'm not sure if I'm doing it right, have I chosen the right parts and are my calculations correct?http://www.ti.com/lit/ds/symlink/tl2575-33.pdf- regulatorhttp://www.farnell.com/datasheets/2059678.pdf?_ga=1.1109745.1783813791.1475409982- capacitors 100uf 25v and 470uf 25vhttp://www.farnell.com/datasheets/1905824.pdf?_ga=1.26488573.1783813791.1475409982- inductor 220uhhttp://www.farnell.com/datasheets/657183.pdf?_ga=1.241887426.1783813791.1475409982- diode PMEG2005ETI've had a go at calculating the ripple voltage, not sure if it's correct or not.88% efficiency3.3v Vout12.5v Vin max52-kHz switching frequency220uh Inductor value 0.000220.06Ohm cap ESR3.3 / (88% * 12.5) = Maximum duty cycle = D = 0.3(Vin max - vout) * D / (fs * L) = 241.258 = inductor ripple currentirc * ESR = 14.475 (mV??) = output ripple voltageI don't know how bad I did, but any feedback is appreciated!

author: suicidaleggroll
author_rank: Super Contributor
timestamp: October 05, 2016, 08:43:08 pm
content: Have you taken a peak at TI's Webench?http://www.ti.com/lsds/ti/analog/webench/overview.page?DCMP=sva_web_webdesigncntr_en&HQS=sva-web-webdesigncntr-vanity-lp-en

author: aaronhance
author_rank: Regular Contributor
timestamp: October 05, 2016, 09:38:11 pm
content: Quote from: suicidaleggroll on October 05, 2016, 08:43:08 pmJust opened it up, wow, thanks for the link!

author: peter.mitchell
author_rank: Super Contributor
timestamp: October 05, 2016, 11:24:01 pm
content: need a bigger diode but otherwise fine.an ss12, ss13, ss14, ss15 etc would work fine.
Choosing Projects to Work On - Page 1
Forum section: electronics / beginners

author: gigavolt
author_rank: Contributor
timestamp: March 19, 2023, 09:47:49 am
content: This might be kind of a dumb question, but I just moved and am setting up my lab again. I haven't done much in terms of electronics projects for the last year while I was moving around for work. Now that I am getting it set up again and want to get back into it as a hobby, I am having a hard time picking a project to start working on. Can anyone share how they start thinking of ideas or learn about interesting things to try?I do have general areas I think are cool like audio, metrology, high voltage, but actually learning about them and finding stuff to start out with that is also cool enough to keep me going is a bit tough right now.

author: shapirus
author_rank: Super Contributor
timestamp: March 19, 2023, 10:12:48 am
content: Hard to go wrong with an electronic dummy load and a voltage reference.

author: geggi1
author_rank: Frequent Contributor
timestamp: March 19, 2023, 11:03:27 am
content: Build a small linear powersupply.Alternative 1.Adjustable with a LM317 or similar Vregualtor.Alternative 2.One with the normal fixed voltages used in electronics.3,3V; 5V; 8V; 12VThe PSU can be build with fixed voltage regulators LM78xx type.Transformer can be scavenged from some old electronics or even a small lead acid charger (4a is plenty).The schematics can be found in the datasheet for the component or in a application note for the component.
Criterias for choosing PWM frequency - Page 1
Forum section: electronics / beginners

author: kallileo
author_rank: Contributor
timestamp: January 02, 2014, 10:24:29 pm
content: Hi and Happy New Year to everybody!I have a permanent magnet, 100W dc pump and I use PWM signal to control its rotation speed.What would be the optimal frequency for PWM signal?Does it matter if the PWM frequency is 20Hz, 2KHz or 20KHz?The only advantage I know for setting the frequency above 20KHz (maximum acoustic frequency) is to eliminate some noise.

author: Simon
author_rank: Unknown
timestamp: January 02, 2014, 10:27:40 pm
content: in reality it does not matter, higher speed will make your switching transistor heat up more, from my experiments with a fan you will get finer control with a higher frequency and be able to get lower speeds without stalling but the lower the frequency the more efficient. I made my fan controller with a 555 and had a selection of two capacitors, adding another capacitor gave more speed without changing the knob because there was less time being wasted on turning the mosfet (or it was probably a BJT actually) on and off.

author: Jon86
author_rank: Frequent Contributor
timestamp: January 02, 2014, 11:12:30 pm
content: Yeah there's not much more other than what's already been said.For a motor it basically doesn't make much difference, I wouldn't go anywhere near as low as 20Hz though, it's going to be really jittery at that kind of frequency.As you mentioned yourself, things like motors can generate noise at lower PWM frequencies. Large motors can produce a ton of really, really horrible noise at say, 1KHz.

author: lowimpedance
author_rank: Super Contributor
timestamp: January 03, 2014, 12:55:30 am
content: Certainly avoid low frequency , however at higher frequencies you may have torque issues, perhaps it would be easier to just experiment to find the optimum operating point for your setup.

author: Psi
author_rank: Super Contributor
timestamp: January 03, 2014, 02:57:59 am
content: +1 for 1khz pwmIt's fast enough that you don't see/hear itand slow enough that you don't lose much heat from the switching.
Choosing retro RAM speed in ns - Page 1
Forum section: electronics / beginners

author: RetroPhase2015
author_rank: Contributor
timestamp: February 28, 2015, 05:52:52 pm
content: Hello, I'm building a Z80 homebrew computer, only I'm actually using an SGS Z08400084 NMOS @ 8Mhz.My question is, is there a formula for working out what speed of RAM I should use?I ask as I'm hoping to build more than one design, possibly with other CPU's such as the Motorola 6800 8-bit in the future.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 28, 2015, 06:11:34 pm
content: You can use whatever you want, as long as you provide the WAIT state logic necessary. For avoiding that, you need memory that provides valid data out before the MPU reads it, which I believe is one or two T-states? So, <= 125ns should be good enough.You can also use DRAM, which will need a little logic to separate the RAS and CAS addresses, provide the strobe and WAIT logic (which is probably now necessary), with the advantage that you have DRAM refresh cycles from the Z80 already (with row address corresponding to the self-incrementing refresh register). But you'll probably just want to use SRAM, because it's way cheaper than needed (you can buy a few megs for as much as a vintage DIP, assuming you don't have some on hand already that is) and doesn't need all this junk tacked onto it.Tim

author: RetroPhase2015
author_rank: Contributor
timestamp: February 28, 2015, 07:51:41 pm
content: Okay, I have some 32k SRAM so I'll use that - thanks

author: SeanB
author_rank: Super Contributor
timestamp: March 01, 2015, 06:45:53 am
content: Do not forget the address decode time, you probably will wanty to use a very fast 74ALS138 as a decoder. The lower propagation delay does help with the decoding, though if you are using 32k you can use A15 as a chip select along with /MREQ using some ALS Nand gates.

author: RetroPhase2015
author_rank: Contributor
timestamp: March 02, 2015, 10:28:17 am
content: Thanks everyone, your advice is greatly appreciated
Choosing scope Siglent 1000-x-e or Instek GDS-2104  - Page 1
Forum section: electronics / beginners

author: ttyridal
author_rank: Contributor
timestamp: June 24, 2018, 05:59:40 pm
content: I'm looking to buy my first scope (changed job, no longer access to a decent lab)Easy (?) question: I can get a used Instek GDS-2104 for about the same price as a new Siglent SDS1104X-E.Does the quality of the instek win out over newer, guarantee covered (and calibrated?) Siglent?Typically doing lowish frequency arm-m0 and AVR stuff. Protocol decoder on the Siglents seems tempting, as the micro rarely lives by it self.

author: wraper
author_rank: Unknown
timestamp: June 24, 2018, 06:05:24 pm
content: You mean old GDS-2104 without any suffix, not GDS-2104E? If that's the case, no way you should pay this much for a completely obsolete scope. I would not pay even EUR 150 for it.

author: ttyridal
author_rank: Contributor
timestamp: June 24, 2018, 07:25:12 pm
content: Yeah, that's what I was afraid of. I would assume the seller added the E suffix if it had one.That's a problem with the low cost brands. They obsolete the models so darn fastThanks for weighting in.

author: wraper
author_rank: Unknown
timestamp: June 24, 2018, 07:28:34 pm
content: Quote from: ttyridal on June 24, 2018, 07:25:12 pmFast? That model is like 12-15 years old. The latest firmware version for it was released in 2010.

author: innkeeper
author_rank: Unknown
timestamp: June 24, 2018, 09:35:30 pm
content: I just did a similar analysis against other options and the best bang for the buck for me at the 500usd price point was the sds1104x-e. And now with the bandwidth hack it really became an easy choice. I may add the AWG later and the MSO options later. for me it was more of an upgrade to reduce my bench footprint and add capabilities. I just got mine this past Friday.

author: ttyridal
author_rank: Contributor
timestamp: July 04, 2018, 10:48:57 pm
content: Quote from: wraper on June 24, 2018, 07:28:34 pmI had some siglent model I can't remember in mind.. though, it might be that I need a history lesson insteadQuote from: innkeeper on June 24, 2018, 09:35:30 pmWhat bandwidth hack is that? Google refuses to tell me about any hacks for sds1104x-e

author: tautech
author_rank: Super Contributor
timestamp: July 05, 2018, 12:15:20 am
content: Quote from: ttyridal on July 04, 2018, 10:48:57 pmFirst mentioned here:https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/msg1612639/#msg1612639
Choosing solder - Page 1
Forum section: electronics / beginners

author: oliver602
author_rank: Regular Contributor
timestamp: December 01, 2011, 06:14:44 pm
content: Im going to do a fair amount of SMD soldering on a project soon. I use standard 60/40 tin/lead solder with rosin core. It's awg22 and I find it a bit big to do a tidy job reasonably quickly. I looked for some fine solder, 26awg ish, of the same composition but couldn't get any.I have had a look onRapid Electronicsand RS and the selection is a bit overwhelming!So far I've established that I should stick with leaded solder.Other than that, what about choosing flux? no clean? low fuming? rosin free? silver loaded? low melting point? less lead and more tin? with copper? It's all a bit confusing. What are the pros and cons of these different compositions?Thanks

author: Balaur
author_rank: Unknown
timestamp: December 01, 2011, 06:32:46 pm
content: Hello,Could I ask you what is your SMD soldering technique?I'm sorry to be a bit presumptuous, and I'm quite sure that you already know and practice this, but you should not directly use the solder with the SMD pad. Thecorrect procedureconsists in usinga lotof flux on the pads and a bit of solder on the solder pencil tip.In this scenario, the actual solder size is not relevant.Personally, I prefer any good quality, recent 60/40 lead with rosin core and a no-clean, tacky, syringe dispensed flux.Cheers,Dan

author: oliver602
author_rank: Regular Contributor
timestamp: December 01, 2011, 06:47:12 pm
content: Thanks Balaur! I haven't been using that technique. Great video

author: Neilm
author_rank: Super Contributor
timestamp: December 01, 2011, 07:26:04 pm
content: Dave also did a couple of videos on the subject.Neil

author: robrenz
author_rank: Super Contributor
timestamp: December 01, 2011, 07:38:09 pm
content: I like the rosin core 63/37 solder it has a single melting point and melts ever so slightly lower than 60/40Kester SN63PB37 44/66 Rosin Cored Wire Solder Dia. .025 1lb $21.63

author: sonicj
author_rank: Frequent Contributor
timestamp: December 01, 2011, 08:18:02 pm
content: Quote from: robrenz on December 01, 2011, 07:38:09 pm+1 but i like the .015 dia
choosing the right fuse of Power supply - Page 1
Forum section: electronics / beginners

author: kgavionics
author_rank: Regular Contributor
timestamp: July 23, 2017, 06:27:57 am
content: HII want to build a dual channel variable power supply.I've chosen the Sharp PQ30RV31 which is a voltage regulator can output 1.25 to 30V @3Amp max.so what would be the fuse rating i use for this dual channel power supply?is it 3Amp fuse?thanks in advance

author: Zero999
author_rank: Super Contributor
timestamp: July 23, 2017, 08:13:42 am
content: The regulator has current limiting built-in. A fuse is still a good idea to protect the transformer, if something before the regulator goes short circuit, such as the rectifier. A 5A slow blow fuse will probably be sufficient. A primary fuse is also a good idea but might not be necessary, if the transformer has a built-in thermal fuse.Note that the voltage regulator has a maximum power dissipation of 20W on a perfect heat sink. In real life it will be less than this. If the power dissipation is exceeded, then the regulator will shut down. This means the 3A will only be available if the voltage, between the input and output terminals of the regulator, isn't high enough to cause the regulator to overheat and shut down.

author: KL27x
author_rank: Super Contributor
timestamp: July 24, 2017, 08:51:56 am
content: You probably want a fuse on the live mains wire. You can calculate the value to be closer to what you need, but there's no need to get crazy exact. It needs to be small enough to save your circuit breaker from tripping. Large enough to handle your PSU's needs. 30V x 3A x 2 channels is 6A @30V. Where's that coming from? Transformer with a 35v secondary? A Switchmode supply? A 3A fuse on the mains should be more than enough unless your PSU is particularly inefficient.
Choosing The right Oscilloscope    - Page 1
Forum section: electronics / beginners

author: MotoDC
author_rank: Newbie
timestamp: October 25, 2014, 09:17:42 am
content: Hi I am an automotive repair student at lvl 4 and we just started using oscilloscopes and I wanted to get one , so found this one on ebay ( Fluke 123 ) bought it and it wont start phoned them and they said 360 GBP for repair LSS ( I cant afford that ) , so I would like to know what to look for when buying a scope and what should I get to suit my needs as motor-vehicle Tech

author: Simon
author_rank: Unknown
timestamp: October 25, 2014, 09:39:41 am
content: you mean you bought a broken second hand scope ? send it back to the seller and get your money back.most oscilloscopes will do you, a cheap 50MHz one is fine for automotive work, or owon have a battery powered oscilloscope that might make auto repair leasier

author: fcb
author_rank: Super Contributor
timestamp: October 25, 2014, 10:22:14 am
content: If you've got a laptop - i'd have a look at the PICO Technologies automotive offerings.www.picotech.com
Choosing the right power value of resistors - Page 1
Forum section: electronics / beginners

author: elefurtronik
author_rank: Regular Contributor
timestamp: March 23, 2023, 09:47:13 pm
content: I would like to calculate the current flows over resistors to determine the wattage of the resistors. However, there is a capacitor at the end and I don't know how to calculate it exactly. I also attach the schematic.

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 23, 2023, 10:00:19 pm
content: Well, if that's 4.5VDCthen the wattage is 0 if you ignore theverybrief time that it takes to charge the capacitor.

author: elefurtronik
author_rank: Regular Contributor
timestamp: March 23, 2023, 10:11:04 pm
content: While charging the capacitor, the current will flow over resistors. How can I calculate this current during the charge? If I choose a low wattage for resistors, they can be burned in some cases. I would like to learn to calculate it for this reason.

author: MarkS
author_rank: Unknown
timestamp: March 23, 2023, 10:29:55 pm
content: Quote from: elefurtronik on March 23, 2023, 10:11:04 pmWhat he's saying is that the current flowing through them, at 4.5v, is so negligible as to be of no concern. Current is voltage divided by resistance. Since the two resistors are in series, it's the same as having a single 6.9K resistor in the circuit. Using that, I = 4.5/6900 = 6.5217-4 or 0.00065217 amps. Wattage is voltage multiplied by current. At 0.00065217 amps, this comes out to 0.0029 watts. It might as well be zero. You'd be fine with 0.01 watt resistors. Just stick 1/4 watt resistors in the circuit and be done with it.

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 24, 2023, 01:11:03 am
content: Quote from: elefurtronik on March 23, 2023, 10:11:04 pmThe worst case, maximum current that can flow is given above in the reply by MarkS.The current decreases very quickly, to zero in about .016 seconds.Any series RC has a time constant that is R (in Ohms) x C (in Farads). The voltage at the capacitor will reach the applied voltage in about 5 time constants.

author: MarkS
author_rank: Unknown
timestamp: March 24, 2023, 01:46:27 am
content: Completely forgot to factor in time...
choosing the transistor - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: July 02, 2017, 06:57:09 am
content: :-[Hello everyone..As a part of my project vu meter project i need some help on choosing a transitor for its switching.What I'm looking for is either a 5V or 12V at the base emitter junction should trigger a 12 v through the collector. The output load current won't be greater than 500mA. So which transistor should I use ??I also need help with choosing the base resistors for the transistors. So could anyone help me with some suggestions??
Choosing USB-C Flir Thermal Camera  - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: August 08, 2023, 03:35:25 pm
content: I'm looking to buy some used Flir Thermal Camera, I want to know what model or feature I must consider to make sure it will be a useful tool for my lab.

author: tautech
author_rank: Super Contributor
timestamp: August 09, 2023, 08:00:29 am
content: Best advice is where all the thermal experts hang out:https://www.eevblog.com/forum/thermal-imaging/
Chopped sine wave power factor - Page 1
Forum section: electronics / beginners

author: Simon
author_rank: Unknown
timestamp: August 01, 2021, 01:57:15 pm
content: So I have my question:QuoteSo the one that has me stumped is the power factor. This is my uni course so as always I treat it like alternate reality and try to stick with the formula's and examples given in the module. But the example of calculating power factor has errors.So all of what I find online talks about reactive loads but this is a resistor. Having calculated the output RMS voltage I can calculate the output RMS current and so have the power used. Power factor is the power that was used over the power that had to be generated regardless of what was used? so the instantaneous amps would still be the input voltage over the load resistance?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 01, 2021, 02:08:37 pm
content: Not all. There should be resources showing the generalized power factor too. Reactive power is the linear / AC steady state case, but it works for any components orthogonal to the source (which, cosine is orthogonal to sine, so reactive power is an example of this).That's probably not a great approach, as you need the Fourier series and Parseval's theorem to find the orthogonal (harmonic sine waves) components, and then to add them up.If nothing else, you can take S = Vrms * Irms (input values), and P being the output power (assuming no losses elsewhere -- no voltage drop on thyristors -- if this is consistent with the material?), then PF = P/S.Which, because Irms is the same (input and output) in this circuit, and the load is resistive so Irms = Vrms(out) / R, it's simply Vrms(in) / Vrms(out).It's maybe not obvious that the second (ratio of RMSs) is equivalent to the first (doing component-wise analysis; though Parseval's theorem basically being RMS over the spectrum, which might be a pretty big hint), so a proof would be instructive.Tim

author: Simon
author_rank: Unknown
timestamp: August 01, 2021, 04:04:20 pm
content: Yes the answer i have given is RMS in over out as if I calculater the powers as the square of the voltage over the resistance I just end up with a ration of the two voltages.
Chopper opamp leakage with output at max/min values? - Page 1
Forum section: electronics / beginners

author: incf
author_rank: Frequent Contributor
timestamp: January 18, 2025, 01:49:59 pm
content: Hi,I have a circuit where I used a TSZ121 chopper opamp. I found that when the output of the amplifier is at its min/max (ie. the inverting and non-inverting inputs are not equal) it shows about 10 microamps of leakage through one of the input terminals.Is this normal for a chopper opamp?Thanks!

author: Kleinstein
author_rank: Super Contributor
timestamp: January 18, 2025, 05:56:23 pm
content: To a certain degree this is normal. Also other OP-amps often have a relatively low differential input resistance.Internally the inputs are switched, between different paths and if there is a voltage difference between the inputs they often start with a different voltage and the capacitance pumps out some charge. 10 µA still sounds high.