hybridfree/eevblog-posts huggingface dataset:
Open collector driving a SSR - Page 1
Forum section: electronics / beginners

author: bootswithdefer
author_rank: Newbie
timestamp: October 16, 2012, 11:41:13 pm
content: Hello,I am trying to design a circuit to control a series of SSRs via an Arduino using the I2C bus. I am thinking of using something like the PCF8574 (datasheet) which has open collector outputs. My SSR board is off the shelf (Sainsmart) and are driven by standard NPN transistors (not sure of exact part, it's SMD and labeled G1). My power supply is a 5V wall adapter.So my questions: how can I connect these two? In my searching it seems maybe I could just use a pull up resister? Is it that simple? Is there a better choice than the PCF8574? Any other suggestions?Thanks,Jesse

author: Psi
author_rank: Super Contributor
timestamp: October 16, 2012, 11:49:22 pm
content: Here's how the ssr board input is wired, just so others don't have to go find the pdf.But you are correct about needing a pullup resistor for each output of that I/O expander.It can only pull high with ~100uA which isn't enough to switch on the NPN in the relay board. A 10K resistor to VCC would fix that.Or you'd could find a I/O expander that can source current, then you waste very little energy and dont need the pullups.

author: bootswithdefer
author_rank: Newbie
timestamp: October 20, 2012, 03:34:37 am
content: Thanks. After some searching I found theMCP23008which will source current.
Open Drain drive solenoid - Page 1
Forum section: electronics / beginners

author: Darlington
author_rank: Contributor
timestamp: June 14, 2025, 09:26:37 am
content: Hi guys!I'm trying to solve a simple problem, but it's complicated at the same time! I want my controller to be able to control both solenoids and other loads at 5V and 12V with a single MOSFET.I had thought of an open drain configuration so that the positive terminal of the solenoid could be connected to the common positive terminal of the 12V or 5V, but this would mean that the flyback diode would not be in anti-parallel between the two ends of the solenoid.What could be a solution?The schematic is attached

author: Manul
author_rank: Super Contributor
timestamp: June 14, 2025, 10:12:11 am
content: Quote from: Darlington on June 14, 2025, 09:26:37 amYou need separate mosfets, at least two. One for 5V loads, one for 12V loads. They can share gate resistors if you wish. Nowadays you can buy mosfets in really small SMD packages, there are also dual ones in one package.

author: Darlington
author_rank: Contributor
timestamp: June 14, 2025, 10:18:10 am
content: Do I need something between my MCU and the two mosfets like a buffer or can the gpio pins usually handle two mosfets?

author: Manul
author_rank: Super Contributor
timestamp: June 14, 2025, 10:44:21 am
content: If you use 3.3V MCU, ensure that you use a mosfet which is "logic level" and turns on fully at 3.3V gate drive. Another consideration is switching speed. Driving two gates in parallel with one GPIO will reduce speed somewhat, that might be important or not. Generally if you don't need to switch super fast, it's good to switch slower, that reduces noise. Generally, don't use overly beefy mosfets for no reason, if you need to switch 1A of current, don't use a mosfet which can switch 100A, they will just be slower switching and load the GPIO more. Be careful if you switch loads which include capacitors, that may cause very high momentary inrush currents. In that case you probably want to switch really slowly, aka soft start. But ensure that you don't violate SOA. So it depends on application and factors above, but you are likely fine to switch two mosfets from GPIO in this circuit. If you need speed or want to use mosfets with higher gate threshold voltage, then you use some kind of gate driver circuit.
Open Drain Output - Page 1
Forum section: electronics / beginners

author: sk614
author_rank: Contributor
timestamp: June 14, 2016, 07:16:40 pm
content: Hi I want to use an open drain output of my LT8620 as an LED Indicator when power is good. I did some sims but not trusting myself. Any problem with this configuration?http://cds.linear.com/docs/en/datasheet/8620fa.pdf

author: Seekonk
author_rank: Super Contributor
timestamp: June 14, 2016, 09:18:47 pm
content: put R5 with LED or you will suck more power out of the chip.

author: rstofer
author_rank: Super Contributor
timestamp: June 14, 2016, 11:06:38 pm
content: 1 Meg of bias current will probably not turn the transistor on.Were it me, I would put the ballast resistor and LED in the collector of the transistor and connect the emitter to ground. I don't know what you plan for LED current but divide it by around 50 and use that for base current. If you want 20 mA of LED current, 400 uA of base current ought to do it. I don't see any reason for connecting the LED circuit to the output but, whatever, select a resistor that will pass 400 uA at whatever the voltage is. If you decide to connect the circuit to the incoming 48 VDC, select a resistor around 100k Ohms. The value isn't critical as long as it gets the transistor into saturation. Vce should be down around 0.2V when the transistor is saturated.Then connect the open drain PG signal to the base of the transistor.

author: danadak
author_rank: Super Contributor
timestamp: June 15, 2016, 12:10:38 am
content: The PG output is a small geometry MOSFET output, with a worst casepull down Reffective of 2K. So use that in your divider calculations withthe base R for the transistor to insure you drop Vbe of transistor belowits threshold, something like .4V or less. Also factor in Vbe T dependence,~ 2 mV / C for constant Ic.Regards, Dana.
Open drain outputs on SN74AHC05N - Page 1
Forum section: electronics / beginners

author: daubmaso
author_rank: Contributor
timestamp: November 11, 2019, 05:39:53 pm
content: Currently working on making a z80 computer on a breadboard. Everything went pretty smoothly but for some reason the inverter chips I happen to have are giving me trouble.The datasheet for the SN74AHC05N says that they have open drain outputs, but when a logic one is applied to one of the 6 inputs the corresponding output is not getting pulled low and is still hovering at my supply voltage (5v) even through a 10k pullup.Since for some reason I can't find anything else on this topic I decided to ask here to see if anyone can think of a reason this is happening, thanks in advance.SN74AHC05N Datasheet:https://www.ti.com/lit/gpn/SN74AHC05

author: daubmaso
author_rank: Contributor
timestamp: November 11, 2019, 05:46:40 pm
content: My bad, turns out my breadboard has a dicky contact at the vcc pin of where I put the inverter. Serves me right for using a 10 year old breadboard for the control logic. Sorry if I wasted anyone's time lol
Open Hantek and other options.  - Page 1
Forum section: electronics / beginners

author: chinoy
author_rank: Regular Contributor
timestamp: April 12, 2022, 01:44:12 pm
content: Not at all happy with the s/w that came with my scope. Hantek 5000 series s/w.Looking for something that allows me to control my scope from the laptop and take screen shots.In my search I found this opensource s/w called openhantek.Will it work with the 5000 series. ?I have not been able to get it to work.Also do you have any software that works better than the default s/w. Provided by the company. Plan to try and see if the 2000 series s/w can work. But there is a dll file missing Has anybody with the 2000 series Hantek got their s/w to work.My model is 5102P.From my readings. The original openhantek was developed for the DSO5000 and DSO2000 series.This is good news. But finding the right version for the DSO5000 is proving hard.They even have an android version. And mac version.

author: chinoy
author_rank: Regular Contributor
timestamp: April 15, 2022, 02:33:28 pm
content: Here is the only info I could find.https://rudysmodelrailway.wordpress.com/2019/09/13/hantek-6022be-usb-oscilloscope-and-6-scope-software-apps-to-go-with-it/comment-page-1/?unapproved=10581&moderation-hash=cb4b27e09e25263a38fb78b80b552430#comment-10581

author: tepalia02
author_rank: Regular Contributor
timestamp: April 17, 2022, 09:35:15 am
content: Have you tried Owon VDS1022 USB Oscilloscope?

author: chinoy
author_rank: Regular Contributor
timestamp: April 21, 2022, 07:04:46 am
content: No I only own a 5210PMy plan is to try and get it to work with my scope.There are 2 - 3 windows versions floating around. One of them allow you to try with any scope.Only confusion is which driver do I try with.Open hantek is open source. I think it should be easy to get it to work with any scope.But for that you will need this info.https://elinux.org/Das_Oszi_Protocol

author: chinoy
author_rank: Regular Contributor
timestamp: April 24, 2022, 08:17:31 am
content: A friend who owns one of the Hantek USB scopes turned me onto the android options.He says there are some mind blowing apps on android which turn your phone or tablet into a complete scope with touch interface.In searching for solutions on Windows I totally ignored the android options.Did a basic search in the play store and found tons of options.Now I have to check them one by one and see what I can use.My Samsung note 9 has otg and I can plug in any USB cable.
Open Load in OFF diagnosis in ProFets - Page 1
Forum section: electronics / beginners

author: misiek303
author_rank: Contributor
timestamp: March 30, 2023, 12:56:24 am
content: HiSome of the ProFets have "Digital signal to enable device diagnosis (“high” active) ". Can you explain what the diagnostics are for and in what case or situation I would use them?Thanks

author: misiek303
author_rank: Contributor
timestamp: March 30, 2023, 01:00:25 am
content: Never mind I found it.https://www.infineon.com/dgdl/Infineon-Off-state-diagnostics-with-TLE9563-64-ApplicationNotes-v01_00-EN.pdf?fileId=5546d46277fc743901785eca0c811c86That is pretty cool!
Open Loop vs Closed Loop Inverting Op Amp Bandwidth - Page 1
Forum section: electronics / beginners

author: BitShard
author_rank: Contributor
timestamp: August 21, 2014, 07:57:54 am
content: Hi all,This is (part of) a question for an Electronics Fundamentals class for uni. I've had a crack at it, but am not quite sure if I'm doing this right, if you guys could help point me in the right direction, it would be enormously helpful.The question asks us to compare the bandwidth of an inverting Op Amp between open loop and closed loop configurations, there are no set values, but arather the question is looking for a generalised answer. (So the equation simply has to imply that the closed loop bandwidth is always going to be bigger than the open loop bandwidth).I achieved this for a non inverting amplifier using the following equation:??0= ?0(1+A0(R1/(R1+R2)))Where:??0is the closed loop bandwidth?0is the open loop bandwidthA0is the open loop gainSince (1+A0(R1/(R1+R2))) is always greater than 0, I could infer that ??0will always be larger than ?0since it's being multiplied by some greater than 1 number.What I can't seem to derive is the corresponding equation for the inverting configuration of the Op Amp, would anyone be able to point me in the right direction?Thanks!

author: owiecc
author_rank: Frequent Contributor
timestamp: August 21, 2014, 09:31:45 am
content: This picture you can find anywhere on google:To understand it, it comes down to control theory. The equation to convert an open loop tf to closed loop tf is:G is your open loop tf. For now assume H is 1. Now think about two cases:1. G >> 12. G << 1How will your closed loop transfer function look for these two cases? Where, on the frequency spectrum are these two cases located?
Open Traces Root Cause - Page 1
Forum section: electronics / beginners

author: vmatoori@gmail.com
author_rank: Newbie
timestamp: March 21, 2019, 02:45:19 pm
content: We have been having this problem of open traces since a while now. Up on cross sectioning we saw low copper evidence. We noticed that the separation is parallel to both sides of the hole and we also noticed that it is on the same location on two different boards. Please see attached picture and any feedback as to how this could have happened would help me to great deal.

author: Jwillis
author_rank: Super Contributor
timestamp: March 21, 2019, 07:09:29 pm
content: What process are you using to etch your boards. Where are you getting your stock copper clad and how well is it washed and prepared before printing artwork and etching ?

author: vmatoori@gmail.com
author_rank: Newbie
timestamp: March 21, 2019, 08:58:07 pm
content: We use Strip-ETch-STrip for etching and It is a standard FR 4 material

author: Kleinstein
author_rank: Super Contributor
timestamp: March 21, 2019, 09:04:29 pm
content: The picture looks like a failure in the plating of a via. So it would be nothing with etching, but more like something in the plating / cleaning process, maybe the drills.

author: vmatoori@gmail.com
author_rank: Newbie
timestamp: March 21, 2019, 09:19:07 pm
content: We did notice today that thickness of copper is lower than Class 2 requirement. We take PTH measurements on 1 panel per lot and did not notice anything unusual lately. Guesstimate is that it is an isolated problem limited to 1 or 2 panels. Low copper looks like a symptom and not the problem. What could have gone wrong that we are seeing these problems?
OpenBench Logic Sniffer - Connect to itself - Page 1
Forum section: electronics / beginners

author: Stephen Hill
author_rank: Regular Contributor
timestamp: July 12, 2012, 10:13:41 am
content: Hi,I've just received my OpenBench Logic Sniffer and I was wondering if it's possible to use it to probe itself, its own circuit?Or would this be a bad idea and if so, why?I guess this question could apply to all type of test equipment like Logic Analyzers and Oscilloscope etc.Many ThanksStephen

author: hlavac
author_rank: Frequent Contributor
timestamp: July 12, 2012, 10:30:25 am
content: You should be fine doing it.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: July 12, 2012, 10:45:30 am
content: A look in the OLS forum shows that some people managed to fry a voltage regulator this way. So I guess it depends on what you probe and how.

author: Stephen Hill
author_rank: Regular Contributor
timestamp: July 12, 2012, 10:48:31 am
content: Quote from: 0xdeadbeef on July 12, 2012, 10:45:30 amDo you have a link to the specific forum thread please?

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: July 12, 2012, 08:50:18 pm
content: http://dangerousprototypes.com/forum/viewtopic.php?f=23&t=4035&sid=ac52c3d125cd0587946159da228328b4On a 2nd look I think he really accidentally shorted 5V and GND on the regulator, though this is not completely clear from his initial description. Indeed you would expect that connecting a probe input to any non-lethal voltage should be no issue.And of course as I bought my OLS last year, probing itself was about the first thing I did and I managed not to damage it
Opening Electric Number Combination Wall-Mounted Locks - Same as Safe from #762? - Page 1
Forum section: electronics / beginners

author: nick_772
author_rank: Newbie
timestamp: October 30, 2016, 05:55:41 pm
content: On EEVblog #762, Dave showed some tricks on how to open safe locks to demonstrate that they are not very safe. I was wondering if these would also apply to locks such as these, or is this a different mechanism?
Opening multimeter - Page 1
Forum section: electronics / beginners

author: Stuartambient
author_rank: Regular Contributor
timestamp: July 20, 2016, 08:55:19 pm
content: This might be a lame questionbut can't figure out for the life of me how to access the battery / fuse area in my meter.The manual says remove 2 rear case screws, neither which exist. The diagram section shows the compartment under the stand. It looks like it should lift up but without just full force and breaking it it's not budging. Could be those are two tabs on the side but those don't do anything either.Anyone familiar with this unit? It's an Amprobe 5XP-A

author: suicidaleggroll
author_rank: Super Contributor
timestamp: July 20, 2016, 08:58:38 pm
content: Looks like a red plastic DMM with a black rubberized casing over it. Have you tried pulling the rubberized casing off and accessing the back of the DMM directly?

author: MosherIV
author_rank: Super Contributor
timestamp: July 20, 2016, 09:00:20 pm
content: The rubber case just pulls off. Try lifting it at one corner, push your fingers in under it and pry it off.

author: Stuartambient
author_rank: Regular Contributor
timestamp: July 20, 2016, 09:05:22 pm
content: See, I knew it was a lame question.I even found the two screws. Thanks guys!

author: Brumby
author_rank: Unknown
timestamp: July 21, 2016, 03:01:34 am
content: Don't feel too bad. We all have had moments like those ... we just try not to mention them - usually.I did have one instance where I was working in retail electronics where a customer had bought a small stereo system. I took the call when they rang a couple of hours later and said the plug was too big and wouldn't fit in the power point. Without any pictures, I was initially puzzled ... for about 10 seconds, then I made a suggestion which immediately solved the problem.Here's an image of a British plug that should suggest what the problem was.....
Operating Region of BJT in Temperature to Voltage Converter - Page 1
Forum section: electronics / beginners

author: prietess
author_rank: Newbie
timestamp: June 11, 2017, 04:02:50 pm
content: Hello!I am attaching the question that I am talking about (added 2 pages).Please look at the pictures attached.Let's say the temperature range is 20 to 45deg.May I ask, for a simple Temperature to Voltage Converter with BJT as shown in this picture, does the BJT has to work in active region (with current gain) for all the temperature range from 20 to 45?Or actually the correct implementation is that the BJT works in saturation for 20, then works in active region for 45 such that we have some transition of operating region that will help us identify the temperature change as well, and hence the temperature sensor is actually working fine?I am a little bit confused. Because logical thinking might suggest that BJT has to be in active (in amplifying stage) when it is operating for some function other than a switch, but all my calculations are showing me that my BJT is transitioning from saturation into active region as it goes from 20 to 45.At the second page, the question asks me to verify if another transistor with a higher beta=100 is suitable to substitute for the one in the question (beta=50)But when I used beta=100, I also get saturation region when temperature is 20deg.If my calculation says it is working in saturation for some temperature range, the question is wrong?I really appreciate anyone who would be able to help!Hope someone can help me please.Thank you very much!

author: bson
author_rank: Unknown
timestamp: June 13, 2017, 06:01:31 pm
content: Why don't you just put it on a breadboard and find out?
Operational Amplifiers: relationships between parameters - Page 1
Forum section: electronics / beginners

author: raff5184
author_rank: Regular Contributor
timestamp: December 01, 2017, 07:24:11 pm
content: Hi everybody,I'm studying opamps and I understood the theory, how they work and the parameters to describe them. But when it comes to the practice it gets a little hard especially when I need to get these information from a datasheet.What I don't understand are therelationshipsbetween the following:Max input signalclosed loop gainmax output swingvoltage supplySo, for example, assuming an inverting op amp, what happens if I increase the inverting gain (using appropriate resistors)? Does it "take" more voltage from the supply reducing the max input voltage I can feed, or is it independent?Or, how does the value ofmaxinput signal that I can feed to the op amp changes with the supply voltage?

author: suicidaleggroll
author_rank: Super Contributor
timestamp: December 01, 2017, 07:29:28 pm
content: The datasheet will tell you the allowable input and output voltage ranges relative to the supply rails, eg: min might be Vss+1.0V and max might be Vcc-2.0V.If you know your supply voltage, then you can find the allowable output voltage range, then use the gain to calculate the allowable input voltage range. Or, if you know your input/output voltage requirements, you can then calculate the required supply rails.

author: Brutte
author_rank: Frequent Contributor
timestamp: December 01, 2017, 08:52:24 pm
content: QuoteI hope you understand this is opamp-specific question.First distinction we must make is the chapter named:a) Absolute maximum rating andb) Operating conditionsChapter (a) describes how to not disable the device permanently. Once you violate those rules - there is no need to read chapter (b).Conditions from chapter (b) describe where the device behavior is qualified.So if chapter (a) starts from: "Thou shalt not put more than Vdd on input pins." then just don't. But that sentence does not say that if you apply Vdd-1V then the opamp would amplify at all.Such details are described in chapter (b) where it is written that: "At 25degC, Vdd-Vss=5V, common mode input voltage range that we tested is 0V up to Vdd-1.5V" for example. Then you can expect input stage to operate as intended.Of course that sentence does not say that the inverting amplifier arrangement with +1V input would output -1V. The output stage operation is characterized with the output swing parameter (and also some plots usually). Most likely it won't output anything below Vss.

author: rstofer
author_rank: Super Contributor
timestamp: December 01, 2017, 09:40:17 pm
content: When you think about it, every number in a datasheet is telling you what you can and can't do with the device. The graphs are particularly telling. It is up to the user to read the datasheet (completely) and understand the features and limitations. App Notes are particularly helpful if they are available.
Operational Amplifiers tutorials - Page 1
Forum section: electronics / beginners

author: Fluxed Matter
author_rank: Regular Contributor
timestamp: July 20, 2012, 04:03:35 am
content: Does anyone have any good recommendations for tutorials on the internet about op-amps. I want to refresh my memory and skills on op-amps. Not so much the theory about how and why they work but about the practical usage and how to calculate the expected voltages from the operation depending on voltage in. Also maybe some example of circuits to build for learning and understanding. Like many post of on here about bench power supply, I too am building my own version based on many designs and Dave's design. I am having a hard time understanding the differential amp part of the circuit. I attached the circuit, which everybody should be familiar with from the Dave's videos, showing the part that I do not understand very well. So far I am leaning toward an op-amp controlled supply for both current and voltage. I still try to figure out the best combination.Thanks for any assistance.Fluxed

author: notsob
author_rank: Frequent Contributor
timestamp: July 20, 2012, 04:11:54 am
content: try nptelhttp://nptel.iitm.ac.inlots of great training videos available

author: Fluxed Matter
author_rank: Regular Contributor
timestamp: July 20, 2012, 04:16:16 am
content: Thanks! I'll check it out.Fluxed

author: Bored@Work
author_rank: Super Contributor
timestamp: July 20, 2012, 04:41:52 am
content: Quote from: Fluxed Matter on July 20, 2012, 04:03:35 amhttp://www.ti.com/lit/an/slod006b/slod006b.pdfhttp://www.ti.com/lit/an/sboa092a/sboa092a.pdfhttp://www.analog.com/library/analogDialogue/archives/39-05/Op_Amp_Applications.zipAnd just for good measurehttp://www.analog.com/static/imported-files/design_handbooks/5812756674312778737Complete_In_Amp.pdfQuoteThese two statements don't match.You might want to rethink the idea that you can get away without the theory behind this and still "figure it out". Especially if you want to do some synthesis, not just analysis.

author: efron
author_rank: Contributor
timestamp: July 20, 2012, 03:23:11 pm
content: I'm sure this will also help youEECE 251 - Op Amps Tutorial 01

author: Fluxed Matter
author_rank: Regular Contributor
timestamp: July 21, 2012, 08:26:18 pm
content: Thanks for all the replies and suggestion. I will being looking at those soon.Bored@Work, your right the two statements don"t match and I guess that is why I am confused.I'll belooking at your recommendations when I am "bored at work".efron, thanks! That's a good video, I wish he was using a differential amp circuit but it was helpful and i have some ideas from it.Fluxed
Opinion about UTG 9005 C :: Function generator 5 MHz - Page 1
Forum section: electronics / beginners

author: Jasonbit
author_rank: Regular Contributor
timestamp: September 07, 2018, 01:54:12 pm
content: Hello folks,I am reading about function generator here on the forum and I didn't find reviews or topics about UTG 9005 C (https://www.reichelt.com/pt/en/function-generator-5-mhz-utg-9005-c-p102158.html?&trstct=pol_0).Also I search about this equipment on channel David (EEVblog channel youtube) but I didn't any information about this equipment. Therefore I decided ask yourself what you think of this model and if there are other equipment in this range. Remember, I am a newbie user and enthusiastic electronic guy. For now I don't need anything very professional anymore.ThanksQuoteI like the offer of wave types that have! Also I like the signal range it offers (0.5Hz to 5MHz). I never use function generator which "frequency counter" but this is will good for my learning.QuoteI like the values of Amplitude. For example, I can use this equipment to test and validate a circuit as signal rectifier (to developer a power supply), thus replacing the use of the transformer (in the testing phase), right?I don't know evaluate characteristics such as "Accuracy / resolution" or "Loss" or "distortion, sine wave" ... so I don't have much to say.QuoteAs I don't known what the frequency counter is for I will try to guess what it is for. This parameter it is important to know what and which voltage I can put on frequency counter. For example, I can put the output signal the traditional circuit 555 astable and counter the cycle of frequency, for example, 1KHz, right?

author: xani
author_rank: Frequent Contributor
timestamp: September 07, 2018, 03:32:57 pm
content: It seems like an older device, before DDS function generators became popular and cheap. Basically before you needed quite a bit of analog wizardry to get it right but with cheap DDS you pretty much just need an output amplifier and a micro to drive it.I'd recommend starting with one of those cheap chinese DDS generators, you can get one for $50 bucks or less:https://www.aliexpress.com/item/Dual-channel-Digital-signal-generator-DDS-Function-Generator-frequency-generator-Arbitrary-Waveform-Pulse-12Bits-250MSa-s/32817504325.htmlAnd overall will have better parameters, just in much cheaper box, and if you ever "grow out" out of it, you'd then know what exactly you miss.There are even more fancier ones:https://www.aliexpress.com/item/KKmoon-FY6600-60M-FY6600-Series-60MHZ-Digital-Control-Dual-channel-DDS-Function-Signal-Generator-frequency-meter/32841230741.html
opinion needed - soldermask and potential shorts - Page 1
Forum section: electronics / beginners

author: AstromechJapan
author_rank: Newbie
timestamp: October 26, 2018, 12:18:30 am
content: I made a bonehead move on my PCB design. If you look at the image below, you can see that I put a GND via (tented) underneath a VDD pin. The VDD pin that is above the GND via is not used (ie: no solder on the pin at all and no corresponding pad underneath of it). only the corner VDD/GND pins are actually used/soldered.What I SHOULD have done is swapped the GND/VDD planes and made the via for the VDD rather than the GND... but such is life and I now have 40 PCBs with this design.The PCBs are a simple LED matrix board. Each LED is capable of max of 60mA at 5V.So, my question is, can I still use these PCB boards? Will the solder mask provide an adequate/workable insulation between the VDD pad and the via?I know this isn't a good solution, nor is soldermask rated as an insulator as it can have air-pockets/pin-holes, etc. This I know.My question is, do I need to scrap these boards, or will it (while not recommended) be ok for the application?

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2018, 01:11:29 am
content: Solder mask will mechanically isolate the pad just fine. But your problem would be solder getting there. Tentet vias mat not be fully covered and may have small regions of copper still exposed. There is no way those regions will make a mechanical contact, but if solder gets there, it may form a bridge.Putting vias like this under tiny devices is not ideal anyway, since vias are slightly raised over the plane of the PCB.

author: t1d
author_rank: Super Contributor
timestamp: October 26, 2018, 07:00:21 am
content: Maybe add a small piece of Kapton, or electrical tape, over the via? Kapton can take the heat, better, but electrical tape might be the better insulator. What about liquid electrical tape?

author: t1d
author_rank: Super Contributor
timestamp: October 26, 2018, 07:03:14 am
content: Remove the pin, from the chip?

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2018, 03:36:21 pm
content: Quote from: t1d on October 26, 2018, 07:03:14 amIt is a 2x2 mm chip. Removing pins will probably damage half of them and will cost more in labor than reordering the PCBs.
Opinions on a begginer made circuit - Page 1
Forum section: electronics / beginners

author: GreySkull
author_rank: Newbie
timestamp: February 10, 2019, 04:04:55 pm
content: Hello everybody!As well as being new to this forum (but not new to the EEVBlog Youtube channel), I'm also pretty much new to making actual circuits with proper schematics and am still learning more advanced electronics. Thus, I had no other place to ask this but here. I have made a circuit based on the ATMega328P that would test some proprietary devices (let's call them stations). The main testing is done on a relay. I am testing diode polarity and coil resistance and if both are good then I will test the contacts of said relay (should be <0.5 ohms). My first prototype of this circuit works pretty well but it was very loosely made. No protections, single rail design and other bad practices. So I decided to amp it up a bit and make it a more permanent design with a PCB and everything.I would like some opinions on this circuit and if I can/should improve it anyway. This is not a production circuit so the standards are not very high at all (circuit attached).Thank you!

author: Kleinstein
author_rank: Super Contributor
timestamp: February 10, 2019, 04:18:47 pm
content: I don't see anything really sensitive like a 24 bit ADC. So there is little to no need to use separate regulators for the relays and the µC. Using just a single supply makes thinks easier as there is no worry about one supply coming up earlier than the other.Similar I see no need for the opto-couplers, just the transistors are good enough if the layout is no horribly wrong.Depending in the wire / trace length the I2C interface might want external pull ups. Only the µC internal ones are rather weak. It may work, but just barely. So a board should have pads for external ones, just in case.It looks like the µC internal ADC is used - so a filter cap at the reference pin is usually a good idea - just in case, one may not need to populate.The µC usually wants 2 decoupling caps close to the chip - not sure if the layout allows the regulators close enough to the chip. So normally one has caps at the µC and the regulators. Usually there is no need for 10 µF behind the regulators. It's more useful to have such caps before the regulator together with a diode to prevent reverse polarity.

author: GreySkull
author_rank: Newbie
timestamp: February 10, 2019, 04:37:20 pm
content: Thank you Kleinstein.I'll remake the circuit above, considering everything you said. Should I calculate the value of the pull-up resistors for the I2C bus or just ballpark it?I will also add decoupling caps between all three power pins of the µC as well as the filter for the AREF.Thank you very much!

author: ebclr
author_rank: Super Contributor
timestamp: February 10, 2019, 10:22:36 pm
content: I would change relays to 24Vdc and use a switched regulator instead of 7805
Optical sensor, ID anyone? (comes from a 1D barcode scanner) - Page 1
Forum section: electronics / beginners

author: onesixright
author_rank: Frequent Contributor
timestamp: July 22, 2015, 10:32:18 pm
content: Hi you all,I have a few pictures of a optical sensor (i think), which is part of a (cheap eBay) barcode scanner (YHD-8200). I don't know much about how they where working, so i opened it up to see. There is a moving mirror with a laser, somehow this sensor is able to read the reflection? I like read more about the type of sensor and how it works.I tried googling the scanner but couldn't find much....Thanks a bunch!

author: helius
author_rank: Super Contributor
timestamp: July 22, 2015, 10:57:36 pm
content: The optic at lower right is a beam splitter. The upper mirror on a pivot is a "wiggler" that bounces back and forth by the electromagnet to its left pulsing on and off. That movement is what scans the laser across the barcode. Light reflecting from the barcode bounces back off the wiggler and enters the beam splitter again. This time half of the light bounces over to the detector.

author: onesixright
author_rank: Frequent Contributor
timestamp: July 22, 2015, 11:24:49 pm
content: Ah , great! Im looking for beam splitter (the one on the yellow circle, right?) but i can't find any components that look like this.You have any pointer to a component like that?Thanks!
optical simulation software - Page 1
Forum section: electronics / beginners

author: lilmantis
author_rank: Contributor
timestamp: July 09, 2018, 05:09:22 pm
content: Hello all, can anyone suggest a software to perform optical simulations for LEDs, reflectors and lenses?

author: lilmantis
author_rank: Contributor
timestamp: July 11, 2018, 11:49:51 am
content: Any ideas?

author: awallin
author_rank: Frequent Contributor
timestamp: July 11, 2018, 12:31:31 pm
content: zemax is use a lot, but commercial and probably $$a good open source alternative to zemax would be nice!

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 12, 2018, 09:42:12 pm
content: The Sketcher in FreeCAD has the ability to daw lines accordint to the refraction law (Shell's Law).FreeCAD is a mechanical cad package though, and this functionality is probably not very advanced.I would also not be surprised if animation packages such as Blender were able to simulate lenses in the raytracing part.This gives some interesting results to the capabilities of Blender:https://www.youtube.com/results?search_query=blender+lens+simulationIt also points to a separate project called "luxrender", which sounds like it might be interesting to you. Blender / Luxrender seems perfectly capable of this, but Blender is a multy headed monster and a bitch to tame / learn. You probably only need a very smal portion of it though...

author: rstofer
author_rank: Super Contributor
timestamp: July 13, 2018, 07:54:26 pm
content: I have no idea what you're trying to simulate but, at a guess, if it involves numbers, MATLAB can do it.https://www.mathworks.com/products/connections/product_detail/beamlab.htmlI did try to Google for 'optical simulation FORTRAN' and got some hits. As FORTRAN is my favorite numeric computing language, I would tend to see if I could come up with enough functions to do the job. In general, FORTRAN lacks the ability to plot stuff without going to some offline process like GNUPLOT.I'm of the belief that there is nothing new in the world. Whatever I want to do, somebody has already done it and if I can just come up with the proper search terms, Google can find it.

author: lilmantis
author_rank: Contributor
timestamp: July 25, 2018, 12:59:54 pm
content: Thanks everyone. It does appear that Zemax is the most popular choice for lens design.
Optics: need for a laser sensor... "array" ? - Page 1
Forum section: electronics / beginners

author: maestun
author_rank: Newbie
timestamp: April 06, 2016, 08:55:31 am
content: Hi to all,A friend of mine has one of these devices:This device has a sensor band (the blue vertical band on the right side) which is able to detect a laser beam in full daylight, even from a big distance (> 100 meters). This used to know if you are aligned with the laser beam, or if the device vertical position is too high / too low.The laser emitter has to be of the same brand, so I guess it is emitted with a series of pulses of given frequency, which is recognized by the receiver.The problem: I want to build the same kind of device (with some addons). For this I must know what the laser detection part is, which technology is used, and if I can source the same kind of part and where... And I have no idea where to start !Could someone explain to me what is the sensor technology used here, and how the laser beam is "separated" from the daylight for the detection ?Thanks

author: rstofer
author_rank: Super Contributor
timestamp: April 06, 2016, 09:30:06 pm
content: Borrow the unit and take it apart!The beam is probably modulated to make detection easier. IR remote controls are modulated for the same reason.

author: maestun
author_rank: Newbie
timestamp: April 07, 2016, 09:09:20 am
content: Yes, I thought about that (although that might not give me much more info about the sensor), but my friend lives far away and needs his device for his daily job

author: Rerouter
author_rank: Super Contributor
timestamp: April 07, 2016, 12:21:46 pm
content: I would imagine a proper sensor at the dead center, the black material spreads the beam wider, and allows them to use cheaper sensors for the rest of the range,From personal experience i know those things are pretty hard to get tracking unless you overlap the center point while moving about, (for say 25m distance)

author: jeremy
author_rank: Super Contributor
timestamp: April 07, 2016, 01:26:03 pm
content: Laser detector arrays == CCD == "digital cameras". I have seen them used many times for laser beam profiling. But I doubt this uses a CCD (or CMOS) detector, it probably just uses two photodiodes. When the signal reaching both is equal you are aligned. When the lower one has more, move up. Etc etc

author: maestun
author_rank: Newbie
timestamp: April 14, 2016, 05:48:28 am
content: Hi to all, and thanks for the answers.I don't think the sensor is made of photodiodes, it seems made from "solar-panel-looalike" stuff. Also, how could be the daylight filtering made ?
Optimal PWM Frequency - Page 1
Forum section: electronics / beginners

author: bumba000
author_rank: Regular Contributor
timestamp: October 21, 2015, 04:54:11 pm
content: I would like to know if there is a calculator or a formula to figuring out the best PWM frequency and duty cycle for an inductor.Thank You, John

author: DimitriP
author_rank: Super Contributor
timestamp: October 21, 2015, 05:41:42 pm
content: Post some numbers and what you are expecting the inductor to do with this PWM frequency or even better what you are expecting to do with this inductor.....

author: bumba000
author_rank: Regular Contributor
timestamp: October 21, 2015, 05:59:47 pm
content: I've built a boost converter. See my schematic and parts list herehttps://www.eevblog.com/forum/beginners/boost-converter-vout-drops-with-load/I have all the solder and trace routing kinks worked out. I want to run a 0.5ohm load at about 5V and 10A from the 18650 battery. I'm having a good bit of success around 22.5khz but I'm sure it could be better. I can only seem to find calculators and formulas to figure out what frequency we're producing as apposed to what frequency we should be producing.Thank you, John

author: bumba000
author_rank: Regular Contributor
timestamp: October 21, 2015, 07:44:48 pm
content: I found out about partsim.com and that too is going to take a bit of learning. I've started a spreadsheet and have begun tracking my results. I'm finding so far that as Vin changes so must the duty cycle and the frequency. This is going to be quite a task, but I'm up for it.John

author: bumba000
author_rank: Regular Contributor
timestamp: October 21, 2015, 08:21:15 pm
content: Thank you. You've just made this a whole lot easier on me. I'll still have to do some testing and tracking to find the optimal frequency, but so far 25kHz is doing pretty well. I'm waiting on batteries to recharge now.

author: bumba000
author_rank: Regular Contributor
timestamp: October 21, 2015, 08:37:26 pm
content: Thanks again. I've had other recommendations in the 30khz to 40khz range at 28% duty cycle. I have spoken with the engineer of the inductor and he tells me that its happy anywhere from 1khz to 1mhz. So, I like and appreciate what you say.While I'm waiting for batteries to charge I've decided to try using an old HP 379349-001 atx power supply to make an adjustable power supply. I have a few potentiometers and LM317T's here to work with. If you're already seeing a problem with this please let me know. I'm going on pizza break now.Thanks again, John

author: xwarp
author_rank: Frequent Contributor
timestamp: October 23, 2015, 08:47:22 am
content: Just curious, is all this to run an atomizer coil for an e-cigarette?
Optimization settings for MPLAB - Page 1
Forum section: electronics / beginners

author: A2
author_rank: Contributor
timestamp: July 15, 2014, 04:40:34 pm
content: I am using1. MPLAB V8.92.00.002. Hi Tech C V9.823. Compiler operation module - ProWhat should be settings for:1. No optimization2. Default optimization3. Minimum size4. Maximum speedI am using below GUI interface for opt settings:MPLAB->Project->Build Options->Project->Compiler->Optimization settings (GUI for settings)Now What should be 'Global' value to be set '1 to 9' for space & speed.Should I tick/untick 'Assembler' options for speed and space
Optional components in scheme - Page 1
Forum section: electronics / beginners

author: Kaio Macedo
author_rank: Contributor
timestamp: November 02, 2016, 04:20:10 am
content: In optional components schemes usually be identified in several ways, for example;NostuffNCDNIDNADNF@*OptionDoes anyone know any more acronym or symbol indicating that the component is optional?

author: Dago
author_rank: Frequent Contributor
timestamp: November 02, 2016, 05:05:50 am
content: DNP has been the most widely used acronym for specifying a component that should not be placed that I've seen.

author: Neilm
author_rank: Super Contributor
timestamp: November 02, 2016, 07:37:50 pm
content: Where I work we use N/F for Not Fitted

author: Cerebus
author_rank: Super Contributor
timestamp: November 02, 2016, 07:55:54 pm
content: DNP - Do Not Populate

author: amyk
author_rank: Super Contributor
timestamp: November 03, 2016, 10:45:02 am
content: I've seen "DY" in some Asian schematics and wonder what it stands for. "Don't Yuse"?

author: Kaio Macedo
author_rank: Contributor
timestamp: November 26, 2016, 06:30:51 am
content: Quote from: amyk on November 03, 2016, 10:45:02 amI also wanted to know.I just got a schematic with DY.Does anyone know what it means?
Options for breadboarding assembly with 2x10 .1" male header - Page 1
Forum section: electronics / beginners

author: Back2Volts
author_rank: Unknown
timestamp: December 21, 2019, 10:41:33 pm
content: Are there any easy tricks ? I do not think there are any adapters available.

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: December 21, 2019, 11:32:03 pm
content: Jumper wires?
Options for dealing with out of range V and I - Page 1
Forum section: electronics / beginners

author: Wrydog
author_rank: Contributor
timestamp: March 28, 2017, 03:41:09 am
content: Hello,I'm working on an H-bridge DCDC-DCAC inverter. When I detect a potentially destructive overvoltage or overcurrent, is the proper response always to shut the device off, i.e. stop switching?Also, I've heard that the threshold can be 150% of nominal assuming your components are rated to far? I this a good rule of thumb? I assume duration would also play a part in choosing whether shut down is needed or not.Are there standard practices regarding this?

author: Benta
author_rank: Super Contributor
timestamp: March 28, 2017, 08:49:08 am
content: Generally, don't go outside the Absolute Maximum Ratings.Youll need to analyze the possible current/voltage combinations that can occur, specially during switching transitions, and make sure they're inside the Safe Operating Area (SOA).

author: jeroen79
author_rank: Frequent Contributor
timestamp: March 28, 2017, 10:14:15 am
content: What will your device be powering?What would be the consequences if the the systems shuts down?If you go for a CC mode instead of a shutdown, how would the load handle the drop in voltage?What kind of margin you want to design for would depend on what you or your client need.Do you need to save money by not exceeding the specifications?Can you afford to spend more on a going above the specs?What would be the cance and consequences of the device failing when used out of spec?
Options: ribbon cable - Page 1
Forum section: electronics / beginners

author: Seaofdep
author_rank: Regular Contributor
timestamp: August 17, 2017, 04:52:15 am
content: Hi, I have a camera gimble with a torn ribbon cable, this particular cable is said to be impossible to get due to the manufacturer not make supplying this item as a single piece. Only way to get cable is to buy the camera and gimble. Being new in this, I'm not sure what options I have Or if there is any other option ? What would you do ?Sent from my iPhone using Tapatalk

author: ElektroQuark
author_rank: Unknown
timestamp: August 17, 2017, 05:32:09 am
content: Make your own?Copy it with a CAD package. They are a bunch of cheap manufacturers that happily will make it for an affordable price. Affordable depends on the price of the camera and gimble.
Opto-Coupler Calculations - Page 1
Forum section: electronics / beginners

author: paul23
author_rank: Regular Contributor
timestamp: July 02, 2013, 08:27:05 pm
content: I need to connect to MCU´s togther through an opto-coupler. Basically one sends pulses to the other, speed is not important as it will be worse case a couple of pulses per second, but generally much less than that.I will be using a Vishay VO615A-8X017T part, datasheet here if needed.http://www.vishay.com/docs/81753/vo615a.pdfBasically the configuration is simple, MCU > Resistor > Anode - Cathode > GND on the input side and thecollectoremitter tied to ground, with theemittercollector going to the other MCU with a 10K pull-up resistor. The reason for 10K is that I already have a few 10K resistors on the board doing other things, so I need less values on the board. Is that OK to do?So if I have understood everything correct, then there is 500uA on the collector (5v through 10K), so I need to supply at least that amount to the LED to get the Transistor to switch on fully. From the datasheet, the CTR is 130 - 260% so if i give the LED the same, 500uA, there should be plenty to switch the transistor on. The LED side is 3.3V, and the LED Vf is 1,05 at 500uA, so I would need 4,5k (4,7K is a better value) resistor.Is that right?Thanks.

author: edavid
author_rank: Super Contributor
timestamp: July 02, 2013, 08:42:09 pm
content: Input side: tie anode to Vcc, cathode to output pin through resistor. You get a little more drive that way.Output side: you have this wrong (typo?) - should be emitter to ground, collector to Vcc through resistor. 10K is OK if you are driving a Schmitt trigger input.Your LED resistor calculation is basically OK, but derate CTR to no more than half the minimum spec to allow for aging etc., so I'd make it 2K.

author: paul23
author_rank: Regular Contributor
timestamp: July 02, 2013, 09:25:30 pm
content: Yeah, that was a typo, I was rushing.I hadn´t thought about aging, that is a good point. Im not sure what the second MCU will be yet, probably an ATMEGA so it will be a schmitt trigger input.Thanks for the other suggestions.