hybridfree/eevblog-posts huggingface dataset:
film capacitor and resistor in series coupled on mains ac, voltages don't match - Page 1
Forum section: electronics / beginners

author: robsims
author_rank: Frequent Contributor
timestamp: November 15, 2022, 07:17:14 pm
content: Hi, i soldered a 0.56 microfarad polypropylene film capacitor in series with a 390 ohm resistor. I connected their other free ends to mains ac voltage. Mains ac voltage is 127 volts and 60 hertz. I measure a voltage of 126.4 volts across the capacitor and a voltage of 10.2 volts across the resistor. So the total voltage of capacitor and resistor is 136.3 volts. Measured mains ac voltage and it is 127.2 volts. Can someone tell me what is wrong here? Many thanks

author: John B
author_rank: Frequent Contributor
timestamp: November 15, 2022, 07:30:45 pm
content: The voltages across the cap and resistor aren't in phase with one another (but the current is).Further more: the sqrt(126.4^2 + 10.2^2) = 126.8V so your measurements work out OK.

author: robsims
author_rank: Frequent Contributor
timestamp: November 15, 2022, 07:38:55 pm
content: Many thanks John B

author: John B
author_rank: Frequent Contributor
timestamp: November 15, 2022, 07:48:41 pm
content: https://www.allaboutcircuits.com/textbook/alternating-current/chpt-1/ac-phase/There's plenty of other good websites which go through the basics of AC circuits. You'll need your trigonometry skills at a minimum, then complex numbers become the easier way to work out AC circuits.

author: robsims
author_rank: Frequent Contributor
timestamp: November 15, 2022, 07:56:33 pm
content: Quote from: John B on November 15, 2022, 07:48:41 pmMany thanks for the information

author: wasedadoc
author_rank: Super Contributor
timestamp: November 15, 2022, 08:02:15 pm
content: Quote from: robsims on November 15, 2022, 07:56:33 pmThe OP asked exactly the same question on 6 November athttps://www.eevblog.com/forum/beginners/should-i-measure-with-a-true-rms-multimeter/msg4506313/#msg4506313and got adequate answers there.

author: robsims
author_rank: Frequent Contributor
timestamp: November 16, 2022, 12:00:44 am
content: Quote from: wasedadoc on November 15, 2022, 08:02:15 pmOMG yes it's true. I forgot about it. Already borrowed some books to study. If i have more questions i'll get back to you guys. many thanks
Filter and Pull-Up Location for Rotary Encoder - Page 1
Forum section: electronics / beginners

author: djex81
author_rank: Newbie
timestamp: February 08, 2021, 03:46:06 am
content: Hello All. I have a quick question. I'm designing a MIDI controller that will have several mechanical rotary encoders. I understand that for mechanical encoders it's recommended to use a simple filter and pull-up resistor on the outputs of the encoder. My question is should I put this filter and pull-up resistor on the same board as the encoder or should it be on the board with the microcontroller? The encoders will be on their own separate board connected to the main board via ribbon cable. The main board will have the microcontroller and other logic. I'm unsure if its better to filter and pull up before the ribbon cable or after it on the main board.

author: mvs
author_rank: Frequent Contributor
timestamp: February 08, 2021, 09:25:01 am
content: It doesn't matter, where you put this components. Do as is more convinient for you or for production.In one-off project, i would tend to make a self contained encoder board with caps and pull-ups, just to be able to reuse it later.In a mass production you can skip reflow process, if only TH parts are used. So no caps and no pull-ups on encoder board, if it does not contain other smd parts.

author: Ian.M
author_rank: Super Contributor
timestamp: February 08, 2021, 09:40:44 am
content: The filter components will also help suppress noise from the ribbon cable and provide some input protection if you put them on the main board.

author: djex81
author_rank: Newbie
timestamp: February 08, 2021, 03:04:31 pm
content: Awesome. Thank you both for your replies.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: February 08, 2021, 03:37:54 pm
content: Another consideration:If you use ceramic capacitors for the filter, then make sure these are not directly connected to the switches of the encoders. Even a 100nF capacitor can deliver peak currents of several amps, and this can easily cause premature wear on the encoder switches.Check the datasheet of your encoder for the maximum current. I won't be surprised if it is as low as 50mA.

author: tooki
author_rank: Super Contributor
timestamp: February 10, 2021, 11:06:06 pm
content: Quote from: Doctorandus_P on February 08, 2021, 03:37:54 pmSo what alternative do you suggest? (Perhaps this question depends on what you mean by "directly": a) with no other components in between, regardless of physical position, or b) in close physical proximity on the board?) As it happens I'm about to lay out a board with two encoders and I was planning to use the filter circuit recommended by Bourns on their encoder datasheets, so I'm happy for any tips.
Filter cap for USB power sink - Page 1
Forum section: electronics / beginners

author: mys_721tx
author_rank: Contributor
timestamp: March 03, 2023, 08:04:19 pm
content: Hello all,Our lab needs to generate a 5V pulse with a foot pedal so I cooked up something dirty-and-quick from a USB power supply. A polyfuse limits the current to 125mA. The foot pedal plugs into the 3.5mm jack and acts as a push switch. (Please ignore the voltage dividers as they are probably not needed on a sink device)While testing I noticed these drops in voltage. The biggest voltage drop is about 4V and its recover time it about 1ms. I gather a filter cap is needed. However I am not certain what parameters the filter cap need to have. Could anyone point me to the right direction?Thanks!

author: thm_w
author_rank: Super Contributor
timestamp: March 03, 2023, 10:39:43 pm
content: To stay "USB compliant" the max you are supposed to use, without additional circuitry would be 100uF. Also the capacitor must be rated at least 6V.Are you connecting to a PC USB port or to a USB wall supply? Maybe the host is cycling power to the device.Also what is inside that foot pedal, is it shorting the two pins together? Then the signal comes out on the "J1 S" pin right.

author: mys_721tx
author_rank: Contributor
timestamp: March 04, 2023, 12:22:39 am
content: I recorded this on the USB port on my scope, I will report back after testing on a wall plug.The foot pedal shorts the two pins and J1 S is the center pin of a BNC connector. Attached is the PCB.

author: thm_w
author_rank: Super Contributor
timestamp: March 04, 2023, 12:34:16 am
content: The waveform you measured is the output of the BNC connector? Or is it the 5V of the USB? Kinda odd as its reading 4V.If its the output of the BNC, are you sure this is not switch bounce from the foot pedal?

author: mys_721tx
author_rank: Contributor
timestamp: March 04, 2023, 12:47:00 am
content: The waveform is the output from the BNC connector. The drops happens after the pedal is pressed. Given there are some spikes on the raising edges, maybe this is a bouncing problem?Yes I will look into debouncing circuits.

author: thm_w
author_rank: Super Contributor
timestamp: March 04, 2023, 01:30:52 am
content: Yeah could be switch bouncing then.If you care about a clean edge, you'll need a proper debounce circuit.If you don't care that much, you can use an RC filter to slow everything way down.

author: mys_721tx
author_rank: Contributor
timestamp: March 04, 2023, 05:32:23 pm
content: So I followed the TIapplication noteand did the math. The debouncing time is about 2.5ms total so I selected a 49.9kOhm resistor and a 25nF capacitor for a time constant of 1.5ms.

author: mys_721tx
author_rank: Contributor
timestamp: March 04, 2023, 10:54:44 pm
content: I also dug around the PCB of the Picospritzer and found a MC14093BCP for the BNC trigger input. I suspect it already debounces the input. I will probe it and report back.

author: langwadt
author_rank: Super Contributor
timestamp: March 04, 2023, 10:59:49 pm
content: Quote from: thm_w on March 03, 2023, 10:39:43 pmisn't it only 10uF ?
Filter capacitor in unregulated power supply - Page 1
Forum section: electronics / beginners

author: Figaro
author_rank: Newbie
timestamp: December 28, 2015, 11:12:17 am
content: When using a 230/12.8 trafo and fidding secondery into a bridge rectifier and then filtering it with an electrolytic cap i get a 17Volt D.C output (unloaded) and 15.80VDC when loaded with a 120 Ohms resistor. Can anybody explain how does the electrolytic capacitor causes the DC go higher then the supplied 12.8V AC ?

author: DimitriP
author_rank: Super Contributor
timestamp: December 28, 2015, 12:00:18 pm
content: No reason to reinvent the wheel....take a look:http://www.bristolwatch.com/ele/basic_ac_rectification.htm

author: Figaro
author_rank: Newbie
timestamp: December 29, 2015, 10:10:31 pm
content: Ok Ok . I forgot my meter (good old Wavetek BD40) measures RMS AC at the trafo output which is almost 18V peak to peak . Minus the voltage drop on the diodes (2 x 0.7 or 2 x 0.3) gives the voltage on the capacitor ( unloaded).
filter design tool question? - Page 1
Forum section: electronics / beginners

author: nick.sek
author_rank: Regular Contributor
timestamp: June 25, 2012, 03:13:59 pm
content: I got a weeks break and I've decide to build a simple audio amplifier and I've been doing the transfer functions for the filters but I was wondering if anyone had a better faster method of designing filters? Like a design tool and a link to that tool. A program would be more desirable than a web site as most of the time I'm not near internet access. Though I love developing transfer functions I'm in a hurry to finish this up so any help would be greatly appreciated.ThanksNick

author: T4P
author_rank: Super Contributor
timestamp: June 25, 2012, 05:09:16 pm
content: Duncan Tone Stack Calculatorhttp://www.duncanamps.com/software.html
Filter digital switching to identify constantly high signal - Page 1
Forum section: electronics / beginners

author: davegravy
author_rank: Regular Contributor
timestamp: April 20, 2024, 03:24:55 pm
content: I have a digital signal as input and I want to output HIGH only if the input has been constantly high for at least 400ms (this is my battery charger's LED indicator and not-flashing == fully charged battery which I want to detect).What's the simplest implementation using discrete components?I understand how to use a 555 timer to generate a 400ms reference pulse on the rising edge of the charger LED output.I was thinking the following would do what I want:(Charger LED output) AND NOT (555 timer output)However it turns out the standard 555 timer doesn't "retrigger" and extend its pulse if the input switches mid-pulse . So I tried a retriggerable version, but the pulse output from the 555 doesn't terminate unless the input pulse terminates. (see falstad circuit where you can see this)Please help

author: davegravy
author_rank: Regular Contributor
timestamp: April 20, 2024, 03:44:38 pm
content: I think I figured it out.circuitStill interested if there's another solution I should consider.

author: xvr
author_rank: Frequent Contributor
timestamp: April 21, 2024, 11:51:49 am
content: 74HC123

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 21, 2024, 12:55:01 pm
content: General term you're looking for is "missing-pulse detector".Right, you can use a transistor or even diode to pull the capacitor down, resetting the timeout. That's the gist of it, and using a 555 for the comparator/latch is fine. You'll probably want to use a CMOS version, skip on the classic bipolar (NE555 etc.) version it's power hungry and not very effective at low voltage.Tim

author: davegravy
author_rank: Regular Contributor
timestamp: April 21, 2024, 02:29:52 pm
content: I need this to work with 1.8V logic but having read the below link, CMOS versions of the 555 will work at this voltage but it's "not in spec".https://www.electroschematics.com/555-low-voltage-operation/Thanks for the suggestion on the 74HC123 but the logic threshold levels also look like not suited to 1.8V logicSN74LVC1G123may work?

author: xvr
author_rank: Frequent Contributor
timestamp: April 21, 2024, 03:19:01 pm
content: > SN74LVC1G123 may work?Sure
Filter Noise in 500ns pulse, encoder pulse - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: January 09, 2016, 12:39:26 pm
content: 1. I have a encoder, which has A,B & Z output. It is 12V powered. Datasheet says encoder can go upto 300Khz at full speed.To work with microcontroller(3.3V) but encoder is 12V so I have added a 1000hm series resistor & 3.3V zener diode. Only used A & Z, didn't use B in my circuit.2. Now I have to detect when rising edge of Z when it comes. But problem is there is random noise comes, which gives false interrupt to microcontroller. The wire length between microcontroller & encoder is around 90cm. I think this could be the problem. However this is case of Z output only, in output A I don't have this problem.3. Attached is pdf. Page 1 shows that I rotate motor at maximum speed, the correct output which I need to detect. Page2 & 3 the noise which cause false trigger to MCU. Page 4 shows correct output at lesser speed.4. How to remove this noise & correctly detect the rising edge. I had placed 0.01uf or 0.1uF also, but in that case correct waveform never appears. Always noisy waveform appears?5. Currently I have placed 1000ohm & 3.3V zener , what is the correct way to reduce 12V at such high speed?6. File is here:http://docdro.id/Lg8dA5S

author: Kleinstein
author_rank: Super Contributor
timestamp: January 09, 2016, 12:52:22 pm
content: For the step from 12 V to 3 V a resistive divider (e.g. 1.5 K and 470 Ohms) could be slightly better than resistor and zener diode - it depends on the zener diode. Up to 300 kHz is not yet that fast. For a fast signal a suitable capacitor parallel the the higher resistor can help a little.This looks like massive ringing on the line due to reflections on the 1 m of cable. One could try approximate termination. So something like a 100 Ohms series resistor at the decoder and possibly something like 100 Ohms and 10nF in series to GND at the µC side of the capble.

author: dom0
author_rank: Super Contributor
timestamp: January 09, 2016, 03:38:02 pm
content: Quote from: Kleinstein on January 09, 2016, 12:52:22 pmThis ringing should not trigger any false interrupts, though.As for the noise, for slow lines (<1 MHz) adding 100 pF to in- and outputs closely to the transition into/outo the system helps. I'd do what Kleinstein suggested, the resistive divider near your MCU, but also add another cap after it, again 50-100 pF or so.

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: January 11, 2016, 04:04:49 am
content: I will try to add 50pf-100pf capacitor at uc end to see the result.12V is tyoical. It can vart from 9-12V. That's why I had placed a zener, so that it any case it maintain 3.3V.That 90cm cable is of decoder, I cannpt cut short it, its with the decoder itselg. All I can add circuitry at uc end.
Filter topology Sallen-Key and MFB: resistor order matter based on their values? - Page 1
Forum section: electronics / beginners

author: Tadaspadas
author_rank: Newbie
timestamp: January 05, 2021, 05:47:02 pm
content: I was designing a needed low pass filter in Sallen-Key configuration and everything goes as normal. Casually look at the Chapter 8 - Analogue Filters by AD, a few reports from TI and follow the procedures. But suddenly, I've got a QUESTION: does the order of resistors matter in Sallen-Key or MFB filters based on their values? From a calculation point of view, there is no difference, but fundamentally there might be some effects?Added a simple buffered sallen-key circuit bellow. Should R1 always be smaller than R2 whatever values they are?It would be glad if you guys could share your ideas.LPF.pdf(77.24 kB - downloaded 294 times.)

author: Benta
author_rank: Super Contributor
timestamp: January 05, 2021, 06:14:45 pm
content: There are indeed ramifications, the main one called "component sensitivity".Component sensitivity refers to how component tolerances influence key filter parameters.As an example: if a resistor value is off by 2%, how much does this influence cut-off frequency, gain or Q.The Sallen-Key filter is pretty bad in this respect, the MFB filter is quite good.With proper component selection, it is possible to keep the sensitivities below 1 for the MFB filter, Sallen-Key is always 1 or greater.The figure indicates tolerance influences. With 1, a 2% resistor or capacitor tolerance will influence key filter parameters by 2%.The maths are not simple, but online filters calculators like the one from TI handles this quite well.

author: mawyatt
author_rank: Super Contributor
timestamp: January 06, 2021, 03:41:22 pm
content: 30~40 years ago we struggled with finding the various R and C values for active filters, especially the C values. This led to the development of an active Butterworth 3rd Order filter with equal value resistors and equal value capacitors. Simply interchanging the Rs and Cs configures from a low pass to a high pass filter and the values are the same for the same corner frequency.Anyway, might be an interesting topology active filter to consider.BTW this was published in EDN long ago, but I can't remember the actual date or issue. No need for a filter calculator as the -3dB Butterworth corner radian frequency is simply 1/(RC), or the corner in Hertz is 1/(2*pi*RC).Best,
Filtering boost converter noise? - Page 1
Forum section: electronics / beginners

author: ok_cool
author_rank: Contributor
timestamp: October 20, 2015, 08:00:10 pm
content: How should I filter out noise coming from 1.6MHz boost converter? Presumably some noise must come out of that IC?Can I use RC and LC filter or is there some good way to deal with the issue?

author: Simon
author_rank: Unknown
timestamp: October 20, 2015, 08:02:57 pm
content: Are you talking the output itself ? yes LC filters. often in datasheets a secondry output LC filter is specified as optional, in theory you can have as many as you like, of course eventually the resistive part of the inductors will cause voltage drops

author: tautech
author_rank: Super Contributor
timestamp: October 20, 2015, 08:10:02 pm
content: Quote from: ok_cool on October 20, 2015, 08:00:10 pmHow much noise?Which device?Most manufacturers datasheets have specific guidelines of layout and component selection to optimise performance.Are you following these closely?
Filtering DC input to board - Page 1
Forum section: electronics / beginners

author: pigrew
author_rank: Frequent Contributor
timestamp: November 06, 2017, 01:16:58 am
content: I'm working a a board that will need 5V and 3.3V inputs (about 500 mA), and I'd like to (due to simplicity) use a 9VDC wall-adapter for its input. I've not decided if I'm going to use a linear or a buck converter for it. The board will have a few analog amplifiers, a battery charger, and a microcontroller.Is there a general guidance for what sort of filtering there should be at the power input? I tried searching this forum, but didn't find anyone talking about how to filter DC input.I found a design that looks reasonable in thisautomotive power supply project on HACKADAY. (see attached)Some thoughts of mine:Is this overkill, and I should be able to use only a fuse and schottky diode, and I should just add ferrite beads/inductors if I notice problems?Should the fuse be closer to the DC input jack, so that things don't fry if the capacitor shorts?Should I add another 100nF capacitor on the input side of the inductors?How do I choose which ferrite bead to use? Is larger impedance at 100 MHz generally a good thing? Or would I need to do full EMC testing to know which one to use. (I know I need to look at the current and max DCR ratings, but there are still many choices.)Should I be using a common-mode choke in addition to or instead of the ferrites?Is it common to add some over-voltage protection, like a zener diode past the fuse?Are there existing designs that I should copy?Thanks!

author: ebclr
author_rank: Super Contributor
timestamp: November 06, 2017, 04:40:25 am
content: Yor design is quite good, but remember that the way you trace the power on your CPU board, will be 100 times more important than this input protection

author: trophosphere
author_rank: Frequent Contributor
timestamp: November 06, 2017, 04:57:20 am
content: QuoteThe fuse and schottky diode components are for protection versus the ferrite beads/low value capacitors which are more for noise filtering.QuoteWhat do you mean by "things"?QuoteThe selection of various ferrites, capacitors, and other components is usually made once you know what you want to filter. Putting components in just for the sake of filtering "noise" is a shotgun approach will pretty much be a tossup as to rather it is effective or not. I would recommend you select the wall adapter you want to use and look at its output to (1) gauge if filtering will be of any added benefit and (2) characterize the ripple/high frequency noise it has so that you may develop an idea of what you are trying to filter out.
Filtering music out of a microphone input - Page 1
Forum section: electronics / beginners

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: June 20, 2014, 03:46:32 pm
content: HelloI have two audio feeds, one from my speakers and one from a microphone which picks up sounds in the room inclusing the sound from the speakers.How would i go about reducing the amplitude of the speakers on the microphone input? It does not need to be perfect but it needs to be enough to effectivly reduce that noise.Could i use op amps to filter it out or would i have to use some form of processor chip to do it?

author: alanb
author_rank: Frequent Contributor
timestamp: June 20, 2014, 04:37:45 pm
content: You will find it almost impossible to filter out the music electronically. What you need to do is to select a the right type of microphone and position it so that it picks up the speech rather than the background music. There are some very good Eevblog's on microphones starting withhttp://www.eevblog.com/2014/04/12/eevblog-602-introduction-to-microphones/

author: Shock
author_rank: Super Contributor
timestamp: June 20, 2014, 04:40:19 pm
content: http://en.wikipedia.org/wiki/Microphone#Microphone_polar_patterns
Filtering signal from transducer  - Page 1
Forum section: electronics / beginners

author: spintinas
author_rank: Contributor
timestamp: February 25, 2018, 03:59:16 pm
content: Hello dear colleagues, i have some questions for you about signal filtering. I want to project daq for my pressure transducer. Firstly, I have a signal from transducer (voltage about 30-60mV), then i design differential amplifier with gain of 20, and the output voltages transducer now are 500mV-1,1V, but when get a signal in osciloscope, there are a lot of noise. So, the question is, what filter is best to use for this type of signal (pressure transducer), also I want to know when it is better to filter signal? Before amplification or after differential amplifier?. I read some information on the internet and I understood, that one of the option for this situation is passive low pass (RC) filter, but I didnt know what value of cutoff frequency should be, and also low pass filter will attenuate my useful signal. So, guys, I would be thankful if you suggest some solutions.Transducer datasheet:http://technel.com/Files/AB-HP.pdfDifferential amp schematics is attached, i use LM324, instead LMC6484.

author: danadak
author_rank: Super Contributor
timestamp: February 25, 2018, 04:09:40 pm
content: 1) You have a differential amplifier whose performance is highlydependent on resistor accuracy (ratio accuracy) to reject commonmode noise. I would advise you use an IA vs roll your own. Thisis an excellent treatise on the use of IAs.http://www.analog.com/en/education/education-library/dh-designers-guide-to-instrumentation-amps.html2) Generally a low pass filer is desired, you trade off its BW versus settling timewhen you design. Use TI filter designer, or Analog Devices, to do the design.http://www.ti.com/tool/filterpro&DCMP=hpa_amp_general&HQS=NotApplicable+OT+filterprohttp://www.analog.com/designtools/en/filterwizard/What are you doing with the result ? Here is a digital filter and differential A/D approach toa bridge sensor problem. Note its shown as single ended, differential is just a setting. A/D is20 bits so can look at a bridge directly in most applications. Cypress PSOC 5LP family.Here is the board you would use to proto -http://www.cypress.com/documentation/development-kitsboards/cy8ckit-059-psoc-5lp-prototyping-kit-onboard-programmer-andRegards, Dana.
Filters for AD9833 Programmable Waveform Generator  - Page 1
Forum section: electronics / beginners

author: ciikucli
author_rank: Contributor
timestamp: October 11, 2012, 03:54:59 am
content: From what I've read, it seems that it's somewhat common to insert a low pass filter with a corner frequency of 30-40% of the DDS clock frequency for waveform generators to simplify the output. Is this true? I've been reading about different types of butterworth, chebyshev, bessel, and passband filters, and thinking about how I'd apply them to higher frequencies in the ham radio and 0-50Mhz band. Any hints/books/suggestions?
Final Review of my First Routing Job - Page 1
Forum section: electronics / beginners

author: ConnorM
author_rank: Contributor
timestamp: January 04, 2018, 08:53:00 pm
content: Hi, everyone has been very helpful so far and I think that I've really made some progress on my first PCB. Could someone have a look and let me know if everything looks good?I was also curious what PCB manufacturer are recommended? I'm not sure if I will solder this myself or if I will choose somewhere where they solder components for you.I've attached top/bottom view of my board along with the schematic!

author: THATguy
author_rank: Regular Contributor
timestamp: January 09, 2018, 06:21:56 am
content: Great work.If you're not comfortable soldering or concerned with time taken.Reflow oven may be an option. You can just get a second hand portable oven to do this, provided you never use it for cooking food again. It will depend on what components you attach (not plastic), may still be suitable, if you only have to add a few plastic bearing components after (sockets etc).For future projects do look into Isolation slots:https://youtu.be/eBzixNYF5K4?t=147https://youtu.be/vfP_65gSSBU?list=PL8D3B363139B67FF3Also stress relieving cutout gaps, if you have some MLC capacitors near mounts.https://youtu.be/QgKY5QWehMEhttps://www.vishay.com/docs/49088/49088_technicalpaper.pdfDave also has a playlist dedicated specially to PCB design:https://www.youtube.com/playlist?list=PL8D3B363139B67FF3

author: Signal32
author_rank: Frequent Contributor
timestamp: January 09, 2018, 06:49:02 am
content: For where to get the PCB - check out PCBShopper.com.

author: phil from seattle
author_rank: Super Contributor
timestamp: January 09, 2018, 06:41:48 pm
content: That PCB looks very hand solderable. I use a toaster oven for reflow all the time and would certainly use it on that board for the SMDs but I wouldn't add ramping up on reflow as part of this project. Keep it simple. I'd save it for the next one.
Finally got a good SHOCK to grin about - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 06, 2018, 11:18:24 pm
content: I have a Fiji digital flash camera that uses 2 AA batteries and they don't last at all in it. Last night I think it used 2 brand new batteries just leaving it on over night plugged into the PC, something strange maybe.So I'm trying to wire in some DC power since I only use it at home. So I took the case off and I'm trying to push the firm solid cooper wires into place in the battery holder. And I got a 1-2 second shock as my finger was wedged in there just on the battery terminals. About on par with a wasp sting I had this fall.It never even occurred to me 1 minute before when looking at the caps for the flash that I could get a shock from bridging the terminals with my dry finger tip.1st real shock I've had since I'm at this stuff in 1-2 years. Hope that's as big as they get.

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 06, 2018, 11:24:54 pm
content: Wow its was from the negative of the battery terminal, to a red wire solder joint on the flash, just next to the battery compartment, AND THERE's 220V still on it between that and the -bat.terminal. WowI drained it down to 55V at 10uA near the end with a neon glow lamp, then an LED. Safe now to proceed

author: Zero999
author_rank: Super Contributor
timestamp: March 07, 2018, 11:33:10 am
content: Yes, it's a well known fact that camera flashes, contain a capacitor which charges up to a hazardous voltage. Fortunately the risk of death is fairly low, as there's a limited amount of energy in the capacitor and it's unlikely the current path will be through the heart, although it shouldn't be taken lightly. What's worse is the charge can persist, even when the battery is removed from the unit.Larger flash units, such as strobes and those designed for use in high speed photography, pose a greater risk of death and serious injury, because the voltage and energy level is considerably higher.
Find if smd resistor is thin film or thick film - Page 1
Forum section: electronics / beginners

author: mercurial
author_rank: Regular Contributor
timestamp: April 05, 2023, 06:28:38 am
content: Hello,I have a bunch of smd resistors with only the value and tolerance printed on the packaging, most are 1206 package, I'd like to know if the resistors are thin film or thick film. Is there a way to find that out, doing some tests externally.I don't have a problem in breaking open to investigate if it comes down to that method.

author: Weston
author_rank: Regular Contributor
timestamp: April 05, 2023, 06:31:09 pm
content: Having a bit of a struggle finding the photos online, but removing the covering and looking at the resistor element would be a pretty easy way to tell.Thick film resistor have a resistive element that is a bit of a black blob. Its visibly raised. Thin film resistors typically have a very thin lighter gray resistive element, often patterned in some serpentine path depending on the resistance value.

author: mercurial
author_rank: Regular Contributor
timestamp: April 05, 2023, 06:48:06 pm
content: I eventually did do it and lifted of the top covering of the resistor and viewed it under a magnifying glass and it did show a black powdery substance which I presumed would be thick film based on the thickness that I found online.The internet searches revealed that thick film layer is around 100um and thin film is around 0.1um.I didn't know that thin film would be grey in color, thanks for that.

author: Jwillis
author_rank: Super Contributor
timestamp: April 06, 2023, 06:28:58 am
content: There are a couple test you could probably do. Thin film resistors can have a tighter tolerance than thick film. 0.1% to 2% for thin film and 1% t0 5% for thick film. Check the resistance and see how close it is to nominal value . That would be the easiest method. Also thin film can have lower parasitic capacitance and inductance. Check with a LCR meter. Thin film have a lower Temperature Coefficient (ppm/°C) than thick film.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 06, 2023, 06:43:17 am
content: Usually thin film resistors have lower TC better accuracy and less excess noise, but on can also be lucky with thick film types and some thin film types / values are also not that great. Even a resistor with 100 ppm/K specs can still be in the 10 ppm/K range, especially for a small temperature range. Similar even a 10% resistor has a chance to be spot on. Of cause if you find than more than 1% off I would assume thick film.For the parasitic capacitance / inductance it depends on the size / value and the difference is too small to tell the difference. Different series may differ by more.
Find inductor value - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: May 01, 2020, 02:35:43 pm
content: Hello friends, happy worker's day, I have been watching videos of calculating the value of an inductor with a function generator and an oscilloscope, having 6 inductors with the value already known, I have not been able to approach these by doing what is proposed in the videos, It really works I am using a FY6900 20Mhz and a rigol ds1054z (ds1104z).in spanishhola amigos, feliz dia del trabajador, he estado viendo videos de calcular el valor de un inductor con un generador de funciones y un osciloscopio, teniendo 6 inductores con el valor ya conocido, no he logrado aproximarme a estos realizando lo propuestos en los videos, realmente funciona yo estoy usando un FY6900 20Mhz y un rigol ds1054z(ds1104z).
Find low voltage trnsformer amperage rating. - Page 1
Forum section: electronics / beginners

author: electronics-whiz
author_rank: Regular Contributor
timestamp: January 22, 2017, 11:01:01 pm
content: I have been dismantling old UPS units for a while. A lot of them were older and used 60HZ transformers. I just too apart one the other day that was rated 550VA output. I intend to use as a step down transformer putting in 120V to the old 120V output. The old primary was 3 wires between the ends is about 16V and it has one center tap lead. These wires appear to be 10AWG.Wondering if there is a way to find the max amperage for the larger secondary winding. I don't know if it would still be 550VA, if so how do I convert that to Amps? I also saw one unit that was like a 2500VA and had 2 transformers in series on the drive side each appeared to be 24V. How would I find the rating on those?I did try to Google on occasion, but they seem to be off brands that all I get info on is people fixing or taking apart UPSs with questions on windings, etc.

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 23, 2017, 11:20:23 am
content: VA stands for Volts * Amperes or apparent power.Note: VA is not Watts real power.So if you have 550VA and 16V then you could get 34A out of it.At 110V it would deliver 5A.The VA rating may apply to the whole transformer.If there are several secondary windings they may share the rating.Also, a lower voltage tap may have the same rating as the whole winding.The size and weight of the transformer and the gauge of the wire can also give an idea of how much current it can deliver.If you really want to squeeze the last Ampere out of it without doing damage you should test it.Apply more and more load and observe the output voltage and temperature.
find max dc offset of function generator given the peak to peak voltage setting - Page 1
Forum section: electronics / beginners

author: Mattjd
author_rank: Regular Contributor
timestamp: October 31, 2018, 07:45:05 pm
content: Hi, I'm writing matlab scripts to send commands to a Rigol dg1022z. I'm trying to idiot proof the matlab script by checking input types and bounds. I've been successful for all inputs (the command, frequency, amplitude, channel) but not for dc offset.Now the dg1022z can have a peak to peak voltage from 20V to 2mV. The absolute value of the dc offset is limited to what the peak to peak voltage is. For example, if the peak to peak voltage is set to 20V then the no dc offset is allowed. If the peak to peak voltage is 2mV then the the absolute value of the max dc offset is 9.999 V.Without taking hand measurements, does anyone know an equation that I can use to solve for max dc offset given the current peak to peak voltage setting?

author: Mattjd
author_rank: Regular Contributor
timestamp: October 31, 2018, 07:56:49 pm
content: oh wait now im thinking of it. 20V p2p means the amplitude is 10 volts. So the absolute value of the offset and half peak to peak setting must be less than or equal to 10V.
Find mosfet by frequency? - Page 1
Forum section: electronics / beginners

author: nandoanalog
author_rank: Contributor
timestamp: March 27, 2016, 10:17:31 pm
content: How do you guys know if a mosfet can turn on and off quickly enough for the job at hand?

author: DimitriP
author_rank: Super Contributor
timestamp: March 27, 2016, 10:49:26 pm
content: In your selection process, where does tonand toffcome into play ?

author: nandoanalog
author_rank: Contributor
timestamp: March 28, 2016, 08:36:25 am
content: So, with all things sorted out, gate capacitance is the enemy?Is there a way to pull current very quickly from the gate once the signal is low?Would this work?The 1pF capacitor is there as a representation of gate capacitance.http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+10.200277308269968+50+5+50%0Ag+400+368+400+400+0%0AR+384+16+432+16+0+0+40+12+0+0+0.5%0A162+384+16+384+96+1+2.1024259+1+0+0%0Ar+384+96+384+128+0+1000%0AR+112+192+80+192+0+2+20+5+5+0+0.5%0Af+320+160+384+160+0+1.5%0Aw+384+128+384+144+0%0Aw+384+368+400+368+0%0Aw+112+160+112+192+0%0Ar+320+160+320+192+0+1000%0Ac+320+192+320+224+0+1e-13+9.598073174038761%0Aw+384+176+384+224+0%0Aw+320+224+384+224+0%0Aw+384+224+384+368+0%0Ad+112+160+144+160+1+0.805904783%0Aw+320+160+256+160+0%0Aw+144+160+256+160+0%0Af+224+208+256+208+1+1.5%0Aw+256+160+256+192+0%0Aw+256+368+384+368+0%0Aw+256+224+256+368+0%0Aw+144+208+224+208+0%0Aw+112+192+112+208+0%0Aw+112+208+144+208+0%0Ad+320+192+256+192+1+0.805904783%0A

author: nandoanalog
author_rank: Contributor
timestamp: March 28, 2016, 09:23:39 am
content: I'd like to drive 5W ir LEDs somewhere below 100 khz. Most likely below 50khz...
Find out the logic board details - Page 1
Forum section: electronics / beginners

author: pvnd.30
author_rank: Newbie
timestamp: November 15, 2020, 07:58:17 am
content: Hi Experts,I am a newbie and have very less knowledge on the logic boards/sensors. Recently i had strip opened a sensor from the RO water system and found that there are couple of sensors that are fried and I was thinking of replacing them mysely but has no idea on what sensors these are and where I can buy them.Need your help in identifying the sensors and probably tge websute where I can buy them.Thanks much in advance.

author: drdm
author_rank: Contributor
timestamp: November 25, 2020, 08:07:11 am
content: We need to find out the markings of the package in order to know what the sensor is.

author: Nusa
author_rank: Super Contributor
timestamp: November 25, 2020, 11:51:12 am
content: I don't think I've ever had an RO system that has any electronics whatsoever. pre-filters and RO membrane to a storage tank, all driven by water pressure.

author: golden_labels
author_rank: Super Contributor
timestamp: November 25, 2020, 02:00:47 pm
content: pvnd.30: even if you reverse-engineer the circuit, you may not be able to fix it. Unless those caps are used for bypassing only and “just any” sane value fits, you will have to determine the right values. And it seems that in both cases the capacitors is what undergone destruction.In the first picture, D1 may be BAT54C: both diodes connected in parallel, both anodes going to the left connector. C1 looks like a tantalum cap, spans betwen the common cathode of D1 and the right connector (let’s call it GND). Counterclockwise from south-west of U1, pins go: to the common cathode of D1 and the positive end of C1, to the left connector and, I believe, to GND. Unfortunately we do not see the upper pins and the trace of C2.What puzzles me is that the boards have only two connections. Any details on where those go? If that would be a sensor, there should be at least 3 pins. Unless they use the same wire for both power transmission and data transfer. But if they do, the diodes and the capacitors are not the part of the sensing circuit: their purpose is to ensure power to the U1 chip. And everything is in that chip alone.edit:actually, looking at the circuit, the diodes, the C1 cap and the connections look like something you would expect at the front of a 1-wire device.
Find That Connector! - Page 1
Forum section: electronics / beginners

author: ciikucli
author_rank: Contributor
timestamp: September 19, 2012, 11:15:22 pm
content: I remember a circular wire connector that screwed on to a threaded female jack. Can anyone point out that connector? Or another with a locking capability so it doesn't come unplugged?

author: robrenz
author_rank: Super Contributor
timestamp: September 19, 2012, 11:54:00 pm
content: You can't expect any help when you give no details of what you are talking about.

author: olsenn
author_rank: Frequent Contributor
timestamp: September 20, 2012, 12:53:04 am
content: It's called a banana socket!

author: nanofrog
author_rank: Super Contributor
timestamp: September 20, 2012, 03:10:04 am
content: Not sure what you're asking (good description would really help, pics even better), but if it's something like a DIN locking connector (M5 ... 7/8"), you might want to take a look at Binder's connector products (http://www.binder-usa.com/).

author: ciikucli
author_rank: Contributor
timestamp: September 20, 2012, 04:57:34 am
content: I don't have much to give, but I was looking for a cable connector capable of transmitting a digital signal both ways in order to interface with a microcontroller. It's going to be attached to a moving object. It has to disconnect, and I though I remembered a connector that either locked to the socket, or had a screw type connector. Banana sockets are not quite right, as I want the male end to have a connector for easy deattachment/reattachment.Thanks

author: Zad
author_rank: Super Contributor
timestamp: September 20, 2012, 05:44:09 am
content: Something like this?http://uk.farnell.com/pro-signal/psg01590/socket-multipole-4way/dp/1280756You can get them in 2/3/4/5/6 pin versions at least. Generic and cheap, screw locking, strain relief etc. Panel mount, or in-line.

author: AndyC_772
author_rank: Super Contributor
timestamp: September 20, 2012, 09:21:56 am
content: Have a browse ofwww.toby.co.uk- they're guaranteed to have something suitable.

author: ciikucli
author_rank: Contributor
timestamp: September 27, 2012, 06:25:19 pm
content: Thanks you guys. One of those should be suitable!
Find the file AN-00084 MT2060 Programming - Page 1
Forum section: electronics / beginners

author: lunavarvar
author_rank: Newbie
timestamp: May 11, 2021, 12:47:50 pm
content: Please help me find the file "AN-00084, MT2060 Series Programming Procedures". This file is only available on the Asian site 52rd, but registering there is a problem. MT2060 SINGLE-CHIP BROADBAND TUNER installed in the Cable Modem ARRIS CM550B, I think to make it all band radio.
Find the frequency of oscillation of this circuit and minimum gain needed. - Page 1
Forum section: electronics / beginners

author: PCBdesigner
author_rank: Newbie
timestamp: February 07, 2022, 07:40:42 pm
content: This isn't homework or anything, it's revision and cannot find anyway of checking my answers.The attached circuit is a Colpitts Oscillator and I need to find the frequency of oscillation and the minimum gain needed of the transistor to make sure the oscillation starts.The input resistance is 200ohm.I have used frequency= 1/2π√ LCt to calculate the frequency to be 3.235Mhz which I am confident with (Checked with online calculator).Now I need to calculate the minimum gain of the transistor:I know I need to use Rnetwork/Rin = (C1/C2)^2But I cannot get the answer that matches the one given.Can someone please show me their workings and answer to the minimum gain required of the transistor?Thanks
Finding a connector based on the cable - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: August 03, 2020, 06:26:16 pm
content: I am trying to find a coaxial cable assembly based on a cable. However, the cable doesn't conform to a specific standard, like RG-58, RG-174, etc. If the cable doesn't conform to a known standard, how should I decide on what cable assembly to use?The cable I'm using is this AWG 30 coaxial cable:https://www.accuglassproducts.com/uhv-kapton%C2%AE-insulated-wire-and-cable/30-awg-coaxial-cableWhat I'm trying to look for is something like this as an example:https://www.digikey.com/product-detail/en/te-connectivity-aerospace-defense-and-marine/6-331693-2/A33777-ND/1124067In essence, I'm trying to find something that will fit an AWG 30 cable. How do I go about it if there is no set standard?

author: TimFox
author_rank: Super Contributor
timestamp: August 03, 2020, 06:53:26 pm
content: If the impedance through the BNC connector is not critical, one can compare standard coaxes to find a dielectric diameter that is equal to or slightly larger than your intended cable. If necessary, maybe you need thin-wall heat shrink to make up the difference in diameters. Then buy the BNC that fits that standard coaxial cable.

author: ioan.koka@gmail.com
author_rank: Newbie
timestamp: August 08, 2020, 10:39:23 am
content: Hi everyone, this is my first post and i decided to add my question here, since it somewhat relates.I got recently in the electronics as a hobby and i'm in the process of buying stuff.Bought various BNC connectors and measured them for resistance just out of curiosity and i have found one that looks faulty. Or is it?As a person with no experience i would not use this one connector in the picture, that measures 10Mohm. What would you do?Thank you.

author: ArthurDent
author_rank: Super Contributor
timestamp: August 08, 2020, 12:28:23 pm
content: There is a difference between resistance and impedance. The resistance of these connectors, pin to shell, depends on the quality of the insulation, can be measured by a DMM, and will be extremely high. The impedance depends on the geometry of the inner pin and the outer shell among other things and cannot be measured by the d.c. resistance range of a DMM, and will be low, like 50 ohms for the BNC connectors shown. There are both 50 ohm and 75 ohm impedance BNC connectors and they aren't interchangeable. The size of the inner pins and other subtle differences can be seen in the photo. A description is in the link.https://circuitglobe.com/difference-between-resistance-and-impedance.html

author: ioan.koka@gmail.com
author_rank: Newbie
timestamp: August 08, 2020, 12:41:32 pm
content: Thank you for your answer sir. I promise i will read that.Now getting back to that particular splitter, would you keep it or get one that measures infinite?Than you again.
Finding a good uncompensated pressure sensor - Page 1
Forum section: electronics / beginners

author: Obsidar
author_rank: Newbie
timestamp: February 22, 2018, 12:42:11 pm
content: Well hello there,I am currently doing an internship and my first real task is to find a good sensor.What is it about or why do I search for a sensor.In the project, that I am currently working on, we want to design a circuit board with 3 pressure sensors for gas analytics, which shall later on be compared with each other.The first sensor is a already well known sensor for us. It is fully calibrated, temperature compensation and provides an amplified output voltage. If you need more information just google for MPXH6250A.The second sensor is supposed to be a self-built sensor, that I will have to work on later.My task at the moment is to find the third sensor, which should have the following specifications:- it has to be fully analog, so no included calibration or temperature compensation- no included temperature sensor- in the best case it provides an amplified output voltage- the pressure range has to be around 250kPa or 30psi- it has to measure the absolute pressureSo these are the specifications or characteristics, that I am looking for.I already found some sensors, that fit in some, but not all requirements...For example the SX30A, SM6841-030 or the SM5420E-030. But all of them provide an output of just millivolts.My search included several websites so as digikey, mouser, octoparts and also developer homepages of for example NXP, Honeywell, Silicon Microstructures, etc. .So do you guys know some sensors that meet the desired specifications or also where else I can search for those sensors?Greetings

author: Nusa
author_rank: Super Contributor
timestamp: February 22, 2018, 12:59:38 pm
content: Truck air brake pressure sensors might be worth looking into.

author: grifftech
author_rank: Frequent Contributor
timestamp: February 22, 2018, 06:25:59 pm
content: what do you mean by absolute pressure? input to atmosphere or input to perfect vacuum?