hybridfree/eevblog-posts huggingface dataset:
How do I discharge a capacitor correctly and safely? - Page 1
Forum section: electronics / beginners

author: Chunkymonkey025
author_rank: Newbie
timestamp: February 20, 2014, 10:42:44 am
content: Hi there, I currently work at a computer repair shop but currently am not able to repair down to motherboard level, I'm able to remove DC sockets and usb ports things like that, but i'm not able to test a motherboard. I would like to know how to discharge a capacitor before I test it without causing any damage to the board.Also I would like to be able to test a capacitor within the circuit, is this possible to do using a multimeter?Thank youChunkymonkey025

author: Psi
author_rank: Super Contributor
timestamp: February 20, 2014, 10:51:29 am
content: A lightbulb of the correct voltage with some probe leads attached is a good discharge load.For testing capacitors in circuit you want an ESR meter.Keep in mind however, that it cannot tell you which cap is bad when there's multiple caps in parallel (as is common on motherboards).It will give you a resistance reading which can be compared to what you would expect for a good cap of the type that's on the board or what you would expect for x number of caps in parallel.

author: granz
author_rank: Regular Contributor
timestamp: February 20, 2014, 02:47:04 pm
content: Motherboard caps will not hold a charge for any amount of time after the computer has been turned off, there are many many parasitic discharge paths. If it's been off for a few hours they will be discharged. If you want to be sure, the usual suggestion is just to hold the power button down when the computer is off, which provides something like a 1k-10k Ohm discharge path.

author: fragilematter
author_rank: Newbie
timestamp: February 20, 2014, 06:27:52 pm
content: Fully agree with @granz above, mobo capacitors should discharge quickly. If you want to be extra safe just use a 1k resistor to short out the cap. Aparently, that's enough even for flash capacitors, at least according to the pentax k100d service manual.
How do I drive the MOSFET stages of my IGBT gate driver? - Page 1
Forum section: electronics / beginners

author: AQUAMAN
author_rank: Regular Contributor
timestamp: November 26, 2016, 09:07:24 pm
content: I need to make a gate driver for an IGBT. It needs to swing from -10V to +15VIn it I need to use a driving stage with 2 NMOS MOSFETsCan someone give some guidance on how to drive these 2 NMOS transistors?A schematic is attachedWill I need to use an upper side mosfet driver to drive the lower mosfet, since its source is connected to -10V rail?What about 2 DCDC converters: I will need -10V and +15V for the IGBT, and -5V and +5V to drive the NMOS driver stage

author: Simon
author_rank: Unknown
timestamp: November 26, 2016, 09:11:16 pm
content: You might be looking at it the wrong way. You want to setup a negative rail to reference and power the whole thing from and then level shirt for signals to that negative rail.

author: max_torque
author_rank: Super Contributor
timestamp: November 26, 2016, 09:17:18 pm
content: https://lmgtfy.com/?q=IGBT+gate+drive+circuit

author: AQUAMAN
author_rank: Regular Contributor
timestamp: November 26, 2016, 09:24:53 pm
content: Quote from: blueskull on November 26, 2016, 09:22:39 pmI know this is much easier, or to use NMOS/PMOS combo, but I have a specific reason why I have to use 2x NMOS

author: nuno
author_rank: Frequent Contributor
timestamp: November 26, 2016, 09:31:32 pm
content: You can probably do it with IC gate drives (to drive your half-bridge FETs).
How do I figure out what this transformer does? - Page 1
Forum section: electronics / beginners

author: dongeo
author_rank: Newbie
timestamp: September 25, 2020, 06:41:33 pm
content: Hi guys, I've managed to pick up some toroidal transformers, but they've only come with labels with model number and manufacturer on them. I've tried googling and looking on their websites, but can't seem to find any record of them anywhere! Is there any way I can find out more info on these?Here's a picture:https://pasteboard.co/JsKPWVU.jpg

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 25, 2020, 07:39:16 pm
content: Transformers can be tested, yes.Quite possible that it's a custom part, in which case you'd have to ask the manufacturer or customer for a drawing. Good luck with that...The first steps are:- Noting dimensions (height, ID, OD)- Wire size if visible (should be able to guess at the outer layer, anyway, and figure out which color wires it's on)- Number of turns if visible (pretty much N/A here)- Measure DC resistance of each winding, including mapping out which colors are connected to each otherThen you can guess at primary, secondary, CT or multitap windings, etc.Pretty safe to apply mains frequency, at low voltage (say from a 6.3V transformer?), to most any winding, and measure the other voltages. This gets ratios.Ideally, you'd do a saturation test as well, using a current-limited source (maybe a transformer with a series resistor) and an AC voltmeter. Apply relatively high voltage to a probably-low voltage winding. See where it starts dropping off: that is, as you increase ACV, the winding V will rise proportionally, until it starts to shy away (rising slower and slow) at some point. That point is the onset of saturation, and is (more or less) the highest voltage that is reasonable to apply, at that frequency.Finally, current rating of each winding can be guessed from overall size, and winding resistances.Tim

author: srb1954
author_rank: Super Contributor
timestamp: September 25, 2020, 10:04:25 pm
content: A quick way to determine the approximate Volt-Amp rating is to weigh the transformer and then compare the weight against other transformers in manufacturer's catalogs.If you have an LCR meter you can easily determine the turns ratio by taking the square root of the ratio of the two winding inductances.

author: nachus001
author_rank: Contributor
timestamp: September 28, 2020, 02:16:09 pm
content: If you have available an inductance meter you can check the primary's and secondary inductances.Usually the primary inductance will be higher than secondary in a step down transformer.If you can check for the wire sizes it will give you an idea of the currents in every winding
How do I find a driver board for an oddball screen? - Page 1
Forum section: electronics / beginners

author: mid
author_rank: Newbie
timestamp: October 09, 2023, 09:28:32 pm
content: A day ago I had no idea what LVDS stands for, so bear with me, I'm new to this.I've got aPanasonic VVX06H007J00 screenthat I'd very much like to use for a project, but I need a board that can drive it from an HDMI signal. I have no idea how to go about finding such a thing since the panel has an oddball configuration (854x480 FWVGA, LVDS 1 ch 8-bit 50-pin) and I can't find any ready to go boards. I've seen a few suggestions here and there online to email manufacturers to get them to flash compatible firmware onto a couple of their boards for me, but is that really a thing for such a tiny order? And where do I find the companies who would bother?Thanks

author: amyk
author_rank: Super Contributor
timestamp: October 09, 2023, 10:06:06 pm
content: I couldn't find a specific firmware for the usual universal LVDS boards (V59, V56, etc.) with that resolution, but if you ask the sellers they may be able to provide one for you.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: October 10, 2023, 05:02:56 am
content: There are special driver boards for such displays, not the common scaler boards, but they are quite expensive - $60 and above in china.For that price, you can get whole set of IPS screen with better resolution and hdmi board included.

author: mid
author_rank: Newbie
timestamp: October 10, 2023, 07:28:39 pm
content: Yeah, I'm trying to decide how badly I want to keep the original display. (This isn't just a question of saving some money, I'm also trying to preserve the original exterior look and feel of the device whose guts I've just ripped out, and I'm willing to trade at least a little bit of cash for that.)So, if I wanted to go that route, where would I find one of these special driver boards and someone willing to sell me one? What do I search for? One of the things I'm running into as I've been looking around is that all the selection is on sites that aim to sell to businesses looking to purchase a crate of components, not a hobbyist who wantsoneof something (plus maybe a couple spares in case he breaks the first one).

author: LinuxHata
author_rank: Frequent Contributor
timestamp: October 10, 2023, 08:21:03 pm
content: taobao.com is a good starting point...Or google -http://www.innovate-st.com/test-box/502128(This is not exactly what you need, but gives an idea about task complexity).
How do I find capacitor values for a simple led circuit - Page 1
Forum section: electronics / beginners

author: accesscontrolforum
author_rank: Contributor
timestamp: September 21, 2014, 09:13:01 pm
content: A few months ago I watched a video about using a capacitor to replace some resistors in a led circuit. It was said the because a capacitor resists a charge/discharge you could do this and lower current draw. I built this circuit and its drawing 70ma. Which is too much.Do you know of an online calculator to help design an Capacitor Resistor LED circuit?Do you know where this video is? (Long shot I know)

author: IanB
author_rank: Super Contributor
timestamp: September 21, 2014, 09:23:01 pm
content: Quote from: accesscontrolforum on September 21, 2014, 09:13:01 pmYou can't use a capacitor to replace resistors in a DC circuit, only in an AC circuit.If the circuit you have built is drawing too much current, increase the resistor values. For example, if you want 20 ma through each pair of LEDs on a 12 V supply, the series resistor should be approximately (12 - 6) / 0.020 = 300 ohms. You could try that, or maybe 330 ohms.

author: Ziltoid
author_rank: Contributor
timestamp: September 21, 2014, 09:26:14 pm
content: I dont think they meant LEDs but normal Lamps.Ben did some videos explaining this some time ago.

author: accesscontrolforum
author_rank: Contributor
timestamp: September 21, 2014, 10:38:48 pm
content: Ziltoid, Thanks, these are the videos I was talking about!IanB, More resistance will effect the brightness correct?

author: IanB
author_rank: Super Contributor
timestamp: September 22, 2014, 01:34:06 am
content: Quote from: accesscontrolforum on September 21, 2014, 10:38:48 pmOf course, but maybe not as much as you imagine. The brightness of an LED varies with the current passing through it, and that current will go up and down as you adjust the series resistance. However, the perceived brightness will not vary much unless you make a big change in current.
How do I get parameters to show up for a spice model in KiCad 8? - Page 1
Forum section: electronics / beginners

author: isitayush
author_rank: Newbie
timestamp: July 04, 2024, 01:35:39 pm
content: Hi Everyone! I built a very simple transformer in KiCad 8 using two coupled inductors. It works when I simulate it with ngspice from it's auto-generated spice netlist. I extracted the relevant part's from the auto-generated spice netlist into a separate file so I could reuse the spice model in my other projects whenever I need to simulate a transformer. This new spice model file is called "transformer.lib" and it contains the following data,Code:***************************************************** Transformer 1P 1S****************************************************** Primary In (PA)* | Primary Out (PB)* | | Secondary In (SA)* | | | Secondary Out (SB)* | | | |.SUBCKT Transformer_1P_1S 1 2 3 4.PARAM Lp=1m Ls=1m k=1L1 1 2 LpL2 3 4 LsK L1 L2 k.ENDS Transformer_1P_1SYou'll notice three parameter'sLs,Lpandkabove. The problem is when I load the "tranformer.lib" file to be used as the spice model for a transformer symbol in KiCad 8, I don't seeLs,Lpandkparameter's in the "Parameters" section of "Simulation Model Editor" dialog box (the dialog box appears when you double click a symbol and click "Edit Simulation Model" button on the bottom). I'm very new to spice, ngspice and KiCad 8 and this is my first reusable model. I'd like to be able to adjust these three parameter's in the "Paramters" section based on the project/circuit needs whenever I want to simulate a transformer with ngspice in KiCad 8 very similar to how you can set values for resistor's and capacitors. I'm not sure what I'm doing wrong here or If I'm missing spice syntax. I've attached a screenshot below for the "Simulation Model Editor" dialog box and you can see the "Parameter's" section is empty when I select the model. How do I fix this?

author: isitayush
author_rank: Newbie
timestamp: July 04, 2024, 03:04:30 pm
content: Solved it! Here's new code for the "transformer.lib",Code:**************************************************************************** Transformer 1P 1S***************************************************************************** Primary In (PA)* | Primary Out (PB)* | | Secondary In (SA)* | | | Secondary Out (SB)* | | | | Primary Inductance* | | | | | Secondary Inductance* | | | | | | Coupling Coefficient* | | | | | | |.SUBCKT Transformer_1P_1S 1 2 3 4 params: Lp=1m Ls=1m k=1L1 1 2 {Lp}L2 3 4 {Ls}K L1 L2 {k}.ENDS Transformer_1P_1SI still don't know how I can add helpful things like "Unit" & "Type" forLpandLs.
How do I get started??? - Page 1
Forum section: electronics / beginners

author: pnutbutters
author_rank: Newbie
timestamp: June 16, 2012, 10:33:16 pm
content: I love electronics and I love to fix them but I want to learn how to design them.The problem is I do not understand how the chips actually function and how the various components can cause different chips to do different things. I do not understand circuit design and how something as simple as electricity flowing through a board can do so many different things.Where do I get started learning a subject as advanced as this???

author: Mint.
author_rank: Frequent Contributor
timestamp: June 17, 2012, 12:37:04 am
content: Well obviously you've already got some experience so thats a start.Next have a look at this thread:https://www.eevblog.com/forum/beginners/electronics-primers-course-material-and-books/tons of useful information there!Also watch Daves videosThats all for now, maybe ill add a bit more later on.
how do I get the negative grid bias voltage without a tap on my power transformr - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: January 28, 2020, 06:49:45 pm
content: is there any way I can get the ~-40v for fixed bias on 6BG6G's without a tap on the power transformer?

author: Ian.M
author_rank: Super Contributor
timestamp: January 28, 2020, 07:36:06 pm
content: Balanced charge pump (i.e. capacitively coupled bridge rectifier) driven by the secondary feeding your HT rectifier, shunt regulated to your desired bias voltage. Choose the charge pump coupling capacitors to limit the current to only slightly over the max load on the bias supply, at min. AC line voltage, so that most of the voltage drop required is reactive in the coupling capacitors, to keep the dissipation in the shunt regulator's feed resistor fairly low.N.B. the bias supply will come up relatively slowly compared to the HT supply, which can be an issue if the cathodes are already hot when AC to the transformer supplying the HT rectifier is switched on.

author: Jr460
author_rank: Regular Contributor
timestamp: January 28, 2020, 07:52:23 pm
content: A quick google shows some ideas of how to do it with getting complicated.http://www.valvewizard.co.uk/bias.html
[solved]How do I half this output voltage! - Page 1
Forum section: electronics / beginners

author: osarus
author_rank: Newbie
timestamp: August 21, 2013, 04:47:08 am
content: LM335 is a temp sensor, you feed it 0.4-5.0mA and it outputs a voltage representing the temp. ~3v at 25C then 10mv/CI need the voltage range to be under 3.3v though! how can I half the output voltage? I tried a divider below with no successThe left circuit works correctly outputting ~3v. I tried added a voltage divider between the output and ground in the right circuit but I think its lowering the voltage to the LM335 to 2.225v! How can I do it without this problem?Thx ^_^

author: Dajgoro
author_rank: Frequent Contributor
timestamp: August 21, 2013, 05:00:16 am
content: Just add a voltage follower before the voltage divider. Or better, make the opamp divide the voltage right away by setting up a amplification of 0.5.

author: Psi
author_rank: Super Contributor
timestamp: August 21, 2013, 05:03:12 am
content: You are trying to draw too much current and are pulling R1 down.Try using 10k for both of the voltage divider resistors instead of 1kChanging the 2k to 1k will help too.

author: osarus
author_rank: Newbie
timestamp: August 21, 2013, 05:07:20 am
content: Thanks Psi ^_^That was stupidly simple!....
How do I know/calculate the number of coil turns I need? - Page 1
Forum section: electronics / beginners

author: ENIAC
author_rank: Contributor
timestamp: December 04, 2014, 02:58:07 am
content: I am trying to build a radio but first I need a coil. But I don't know what formula I need in order to calculate the number of terms need.Please explainThanks

author: w2aew
author_rank: Super Contributor
timestamp: December 04, 2014, 03:11:58 am
content: The first thing you need to know is what value of inductance do you need? This will depend on the frequency range being used, and the surrounding circuitry. If you know the inductance, you can use one of many online calculators to figure out the number of turns. Here's an example for an air-core inductor:http://www.daycounter.com/Calculators/Air-Core-Inductor-Calculator.phtmlThere are others for toroidal inductors, etc...
How do I make a simple dc constant temperature controller - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: July 27, 2018, 08:52:33 pm
content: I hope that one of you can help me constructing a simpel diagram:-)I need to keep the temperature on a heatsink at +25 degrees celsius +/- 0.5 degrees.It is to keep some IC chips at there optimum temperature the whole time.If it is possible, it could be fantastic if a dual color LED could change color from i.e. green when inside the allowed temperature and maybe red when outside.Hope that my explanation is sort of clear.

author: Muxr
author_rank: Super Contributor
timestamp: July 28, 2018, 05:22:22 pm
content: Your initial question is too vague. You need to expand on your requirements a bit.How are you measuring the temperature of the heatsink? Do you just plan on sticking some sort of a sensor on the heatsink?Are the ICs you plan on keeping at 25C heating up on their own when they are in operation? Or are you looking for an Oven controller circuit? If not are you looking to control some sort of a fan?

author: Zero999
author_rank: Super Contributor
timestamp: July 28, 2018, 07:25:18 pm
content: Quote from: FriedMule on July 27, 2018, 08:52:33 pmThen you'll need both a cooler, especially this summer, as well as a heater. A thermoelectric cooler/heater is probably the best way to go. To change from cooling to heating and vice versa, all that's needed it the direction of the current to change.
How do I make a simple XTAL oscillator to test out my scope?  - Page 1
Forum section: electronics / beginners

author: Beamin
author_rank: Super Contributor
timestamp: October 07, 2017, 03:08:33 am
content: I have some 36MHz and 17.something MHz crystals and I would like to make a simple circuit to test out my new scope. Does the design dictate what kind of wave they output such as square vs sine? When I search nline I find Xtal circuits but they seem to be part of more complex circuits and I just need them to oscillate. I don't have any other logic beside a 555 just regular through hole parts to work with including some RF trans and jfets.

author: lordvader88
author_rank: Frequent Contributor
timestamp: October 07, 2017, 03:19:18 am
content: I'd say make so RC oscillators, and some LC oscillators at typically lower freq. 1st. For the sake that at really high F, the signal might be so small on your scope that u chase noise for awhile wondering if its the signal or not.Regardless look up some Collpits, Hartley, Miller, etc oscillators for LC and crystal circuits. I usually add variable res/caps whenever possible so that I can see if stuff changes, why not...and here' "Crystals Made Clear ptII)http://techdoc.kvindesland.no/radio/ymse1/20061216154510328.pdfI just through together a few oscilattors on a little vero-PCB. And I used 8p DIP sockets, to plug any wired the same transistor, and caps/xtal/inductor/s into itWorked a charm and I can see it on my scopes, and no doubts if the are operating.I need JFETs in CANADA NOW, not 3 months from now from China

author: rdl
author_rank: Super Contributor
timestamp: October 07, 2017, 05:41:31 am
content: You can make simple square wave crystal oscillators using CMOS logic chips. I've used 7404 and 4521, but you don't even really need the crystal just for messing around. RC oscillators are fine as long as you don't need super stability.

author: bjcuizon
author_rank: Frequent Contributor
timestamp: October 07, 2017, 12:12:14 pm
content: How about something like w2aew's:
How do I measure anything with a piezoelectirc load cell (KIAG Swiss Type 9011) - Page 1
Forum section: electronics / beginners

author: MysteriousH
author_rank: Newbie
timestamp: October 23, 2024, 07:27:09 pm
content: Hi!So I have a KIAG Swiss Type 9011 Load Cell, datasheet available here:https://www.kistler.com/INT/en/cp/piezoelectric-force-sensors-90x1c/P0000576The jist of it is that I would like to use it, but googling has failed me (I presume I am simply searching the wrong terms) and my attempt at performing some measurements has all but confused me.Since it is a piezoelectric load cell, my understanding is that it essentially generates a small voltage when a force is applied, so what I did to try to understand this is:- Connect it to a Arduino Nano analog port, with a 1MOhm resistor in parallell, and printed out the analog output. Doing this I got what I presume to be noise? When I pushed on it I got some measurements, but they were very delayed relative to when I applied the force. The measurement repeated as pulses a couple of times before settling at zero. Applying force by hand and by use of a benchwise showed no difference.- Next I connected it to my old analog oscilloscope, played around a bit with settings, but applying some or alot of force I was getting the same, really noisy pulses, with no clear difference in magnitude.The load cell is capable of 15 kN, with a sensitivity of -4.37pC/N and with the benchwise I am guesstimating I was applying a couple hundred newtons.When performing the above mentioned measurement my expectation was that I would observe a linear increase in voltage as I increase the load.Any help with terms to search for or settings etc. to use would be greatly appreciated!

author: Kleinstein
author_rank: Super Contributor
timestamp: October 23, 2024, 07:58:17 pm
content: The piezoelectric load cell has a rather small capacitance (some 17 pF). The cable may add a little to this. So even just the 1 M resistor quite fast discharges the capacitance (the charge flows away) and the signal is thus only transient or the AC part. So the time constant would be on the order 17 µs to maybe 200 µs with a bit more cable.Normally one would use the load cell with a charge amplifier. So a kind of integrator (low bias OP-amp and some 1 nF in the feedback) with maybe some 100 ohm of resistor between the load cell and the integrator input. One would at some time zero the charge amplifier ( bridge the capacitor via a momentary switch) as even with a charge amplifier this load cell can only measure changes in the load, no absolute value.If the resistor is used to contineously restore the DC level this would be a rather large value, more like 1 Gohm range or a T circuit to simulate.For a test signal I would use something like a pendulum to create a periodic force and thus an AC signal at the output.For fast playing with a piezo sensor one could try a piezo disc like found in beepers / watches or smoke detectors. These usually have a larger capacitance and may be not as high in impedance and easier to handle - these work directly on the scope.
How do I measure positive and negative voltage with a microcontroller? - Page 1
Forum section: electronics / beginners

author: Degesz
author_rank: Newbie
timestamp: September 16, 2020, 06:02:47 pm
content: Hi, I'd like to build a DIY multimeter and I'm stuck at measuring negative voltage without blowing up my ADC.I know I could add a DC offset so 0v would be 1/2 Vcc but that would cut my accuracy in half. Is there any other trick to do this? What method do commercial multimeters use?

author: MosherIV
author_rank: Super Contributor
timestamp: September 16, 2020, 09:59:18 pm
content: Depends on the ADC. The ADC needs to have a floating or relative mode, so that the ADC ground is biased to be in the middle of the measurement range. Obviously you are going to loose resolution this way.Commercial dmm use 'multi slope conversion' technique. The measurement is done by using an integrator which generates a linear voltage ramp - this is the 'slope' part. A counter is started at the ramp start and the ramp voltage is compared to the voltage being measured. When the voltages match, the count value is latched (this is the measured voltage value). The voltage ramp is then ramped down and the count is then checked again, this is the 'multi' bit.

author: pqass
author_rank: Super Contributor
timestamp: September 16, 2020, 10:26:02 pm
content: Maybe try a precision rectifier and a comparator to flag which way (+ or -).EDIT: see schematic below.
How do i messure a RJ232 Cable - Page 1
Forum section: electronics / beginners

author: FireStriker
author_rank: Newbie
timestamp: September 21, 2019, 07:13:17 am
content: Im a very fresh newbie, Been watching EEVBlog for a while but just got my first muiltmeterI would love some tips and tricks but i have some questions in relations to measuring stuff for my Logitech racing wheel that im remaking a cable that would of come with it when it was new.When measuring voltage on a connector, for example something like a USB plug (which i know the pinout off the top of my head), how do you measure voltage?I would guess that you touch 1 Pin with the red probe and COM would go to ground.This cable would go from RJ232 to USB and i want to double check pinouts and voltages so i dont fry anything.So far pin 5 is Ground which is correct to the pinout im using to recreate this cable but for the rest of the pins im so fresh i dont quite how to figure them out, like confirming Data + and Data - as well as the power line.Chris

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: September 21, 2019, 07:55:05 am
content: The best and safest way would be to use the summing (resistance measurement with a beep) function of your MM and measure each pin at each end of the cable. If it beeps or just show the value in ohms they are connected.No need to connect it and measure voltages.
How do I modify this strobe light circuit to light when I want it to? - Page 1
Forum section: electronics / beginners

author: ticktock3t
author_rank: Contributor
timestamp: November 29, 2015, 05:54:00 am
content: I'm currently working on a project at my university where we are trying to observe the movement droplets. It is a centrifugal microfluidic device that has been glued to a CD and placed on a motor which spins the disc. Unfortunately, it's a cheap motor which doesn't have a steady rpm and it shifts around a lot. To view the droplets we used a standard off the shelf xenon strobe light but because of the unreliable RPM we can't actually see the formation of the droplets. To get around this we took apart the strobe light circuit and are trying to come up with a way to flash the xenon light source every time the disc complete a full rotation. We were thinking about having a metal rod stick out and two brushed wires,connected to the strobe light circuit, lie over the disc and when the rod touches both wires it completes the circuit and trips with xenon light. I'm not exactly sure where to place the wires to do this as the POT controls the speed of the strobe light. I am following this strobe light schematic and trying to compare it to the circuit board I am working with:http://www.xenonflashtubes.com/schematics/My Strobe Light Circuit Board:http://imgur.com/a/Zrwrn-The main(large) capacitor is 47uF

author: Seekonk
author_rank: Super Contributor
timestamp: November 29, 2015, 06:56:17 am
content: How large is the disk? I had a machine with a 15 inch metal disk that I drilled a hole in and placed a 1/16 inch neo magnet in that balanced ok. Pickup was a hall sensor that worked fine at 2,000rpm. That could also be done with reflective tape and LED pickup. Then just drive a transistor. Wire pickup wouldn't be reliable.

author: oldway
author_rank: Super Contributor
timestamp: November 29, 2015, 08:36:39 am
content: I think it would be easier to stabilize the RPM of the motor than to modify the strobe circuit.Feeding the DC motor with a regulated voltage should help.I recomand to use a resistor (calculated to have the same current as the motor at full load) in parallel with the motor to obtain better regulation. (act as a 2 quadrants power supply)

author: Zero999
author_rank: Super Contributor
timestamp: November 29, 2015, 11:26:59 am
content: It's very difficult to stabilise the motor speed without some kind of feedback from the strobe.It's probably best to buy a strobe with an external trigger. For safety sake there needs to be some form of electrical isolation between the trigger circuit and the strobe.
How do I pick proper diode? - Page 1
Forum section: electronics / beginners

author: redgear
author_rank: Frequent Contributor
timestamp: September 20, 2020, 08:21:53 am
content: I am using 1n4148 and a zener diode to suppress surges when turning off the relay.After doing some reading, I found a diode such as 1N4148 can be used. But it comes in different rating. How do I calculate the voltage and current ratings for the diode? Should any voltage greater than 2 times the relay's coil voltage be a correct choice? How to calculate the current rating?For the zener diode, a fellow forum member told any voltage greater than 10% of the relay's coil voltage and less that 10% of transistor max voltage is fine. But how do I calculate the required power rating?Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 20, 2020, 10:44:35 am
content: Peak current equals coil current at the moment of turn-off, and drops over time from there.Unless it's a big industrial contactor, I think you'll have a hard time even finding a diode that is too small to use. Instead of 1N4148 anyway; for the zener, it might actually dissipate enough power that a too-small part may be out there.A note about max, the zener voltage is related to transistor voltage if it's wired ground to output (for a low side transistor). For across-coil position, subtract supply max voltage from that rating.The pulse duration is somewhere between the lossless case (t = L dI / V) and the short-circuit case (t >= 3 L / R_DC), depending on exactly how much voltage the zener is dropping. Probably a few ms.The full analysis would use the diode's transient thermal resistance to calculate temperature rise from the pulse. For the single clamp diode case, we can shortcut this by simply noting the diode handles more current than the coil does, period. For example, a relay coil rated 12V, 200 ohms, draws 60mA when on; 1N4148 is rated 300mA or so. Who cares. For the zener, the same applies, using its power rating. Say we choose 1N4742 (12V 1W): the coil dissipates 0.72W continuous at 12V, so the also-12V zener dissipates a peak of 0.72W and drops off quickly over time. Who cares. A 1N5242 (12V 0.5W) would not pass by the same rule, so we might look to the transient thermal resistance (if provided). Appnotes may give guidance here. Or just shop for TVSs, which are rated by surge handling.Tim

author: redgear
author_rank: Frequent Contributor
timestamp: September 21, 2020, 07:00:06 am
content: Quote from: T3sl4co1l on September 20, 2020, 10:44:35 amThank you. Understood
How do I post? - Page 1
Forum section: electronics / beginners

author: sb37_dude
author_rank: Newbie
timestamp: February 26, 2021, 06:34:38 pm
content: I was wondering, how do I post a question on a particular forum? I wanted to post/ ask question on the Manufacturing foruem and I was unable to.Sorry for the noobie question....

author: MarkF
author_rank: Super Contributor
timestamp: February 26, 2021, 11:47:35 pm
content: Just open the "Manufacturing & Assembly" topic(instead of the "Beginners" topic you selected to create this post)and click the "NEW TOPIC" in the upper right corner.
How do I power these mini water pumps? - Page 1
Forum section: electronics / beginners

author: snipe
author_rank: Newbie
timestamp: December 23, 2020, 03:11:38 pm
content: https://www.ebay.co.uk/itm/Mini-5V-1-0A-USB-Cable-MicroWater-Pump-Submersible-Pump-Pump-Tool-Fountain-X8F1/184541552182?hash=item2af7889e36:g:jB8AAOSwEYZfYTiZ&autorefresh=trueI would like to run 10 of these and was wondering what I can buy to plug them all in and run them with one UK plug.

author: liviu.gelea
author_rank: Contributor
timestamp: December 23, 2020, 03:56:14 pm
content: The USB is just there as a "convenient" power source. Frankly I'd cut the connector and just use the two wires like a normal DC mini motor.I'm suspicious of that 1A rating... It's probably the stall current as I cannot imagine that thingie being a 5 watt constant load motor. Howevertheseojnly have half the estimated flow while using 150mA

author: snipe
author_rank: Newbie
timestamp: December 23, 2020, 04:47:56 pm
content: I don't know what to do with those wiresCan I just buy one of those USB multi ports and plug the port into a power supply instead of a PC? That way I could add or remove pumps when I want by just unplugging them. I don't want to solder anything.

author: CJay
author_rank: Super Contributor
timestamp: December 23, 2020, 05:08:45 pm
content: You certainly could do, but they take quite a bit of power so you are going to need some chunky USB power adapters, it's best to have one that's capable of supplying a good bit more current than the p[umps need because they'll take quite a bit when they start up and when they're under load.Definitely wouldn't plug one into a PC, I've seen nasty things happen (it probably won't but best safe than sorry.)

author: Zero999
author_rank: Super Contributor
timestamp: December 23, 2020, 09:18:04 pm
content: Quote from: snipe on December 23, 2020, 04:47:56 pmYes, this would do the job. It's rated to 60W, which will be more than enough.https://www.amazon.co.uk/Anker-Compact-10-Port-PowerPort-Charging-Black/dp/B00YSA0WI8/ref=asc_df_B00YSA0WI8/?tag=googshopuk-21&linkCode=df0&hvadid=309785494452&hvpos=&hvnetw=g&hvrand=16218671633313167723&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006644&hvtargid=pla-563537383888&psc=1

author: mikerj
author_rank: Super Contributor
timestamp: December 24, 2020, 05:33:19 pm
content: It should go without saying that you need to keep the USB charger well away from the water the pumps will be in. If there is any danger of it being splashed with water you will need additional protection to prevent this.
How do I program an LED to react differently depending on battery status? - Page 1
Forum section: electronics / beginners

author: Marmotta
author_rank: Contributor
timestamp: February 24, 2017, 05:45:50 pm
content: So I had a bit of a Google for this and couldn't really find anything, so I thought I'd post it here and see what suggestions people can come up with. I'm making a project using a rechargeable 3.7v battery and a single LED and I really wanted the battery to act differently depending on whether it is in normal operation (constant), low battery (flashing) or charging (maybe pulsing). I thought there would be quite a bit of information on this sort of thing, but there either isn't or I've just been using the wrong search words. I know I could probably create the flashing low battery and pulsing charging LED signals using quite a lot of circuitry for a small project with some timers and a lot of passives, but I was wondering if there's a specific IC or code out there that could take care of everything?

author: rstofer
author_rank: Super Contributor
timestamp: February 24, 2017, 06:21:52 pm
content: Almost any microcontroller with an A/D input and enough digital outputs to control the LED.Maybe just a single 8 pin chip like PIC10F220http://www.microchip.com/wwwproducts/en/PIC10F220

author: Electro707
author_rank: Contributor
timestamp: February 26, 2017, 12:49:11 am
content: You could buy a battery monitor IC like the DS2745Datasheet:http://datasheets.maximintegrated.com/en/ds/DS2745.pdfThis and some code should get the job done

author: kosine
author_rank: Regular Contributor
timestamp: February 26, 2017, 12:06:40 pm
content: A cheap 8-pin microcontroller will give you a lot of flexibility for minimal cost and least number of additional components.If you can use an Arduino, an ATtiny13 would be a good solution. (You just need to install the core13 files and use the Arduino to programme the Tiny13 on a breadboard, only 6-wires required. Long how-to thread here:http://forum.arduino.cc/index.php?topic=89781.0)An out-of-the-box tiny13 runs at 1MHz and works direct from 1.8V to 5.5V - so just hook up to your battery. (You don't need to burn any bootloader either - just upload the code.)It also has a convenient 1.1V internal reference for ADC. Divide down your 3.7V with two resistors (maybe 47k and 20k) and you've got your voltage. Use a digital out (or PWM) to drive your LED through a (say) 470R resistor and you're done.(Output pins can source up to 10mA at 3.7V, though the output voltage may drop to about 3V at that sort of load. A 470R current limiting resistor will give you about 4mA, which should be loads for basic LED. Buffer the output through a transistor if you need more.)
How do I read an LSF file? - Page 1
Forum section: electronics / beginners

author: BanksySan
author_rank: Newbie
timestamp: March 24, 2018, 07:17:48 pm
content: I've got an LSF file generated from a GW Instek oscilloscope (attached).How do I read this file? Are there existing applications that read it, or a spec for me to write something to read it?Thanks

author: 0xfede
author_rank: Regular Contributor
timestamp: March 24, 2018, 08:43:45 pm
content: Hi BanksySan,there is a nice module in MATLAB for those files called lsfreader(datafile).Here you can find more info:https://it.mathworks.com/matlabcentral/fileexchange/54090-lsfreader-datafile-?focused=6559621&tab=functionBest,0xfede

author: BanksySan
author_rank: Newbie
timestamp: March 24, 2018, 09:42:52 pm
content: Cheers.I don't speak MatLab unfortunately, but I'm sure with a bit of Google I can unpick the syntax. If nothing else, it did confirm that this is a propriety format from GW. Looks like an undocumented one at that.SighDave

author: BanksySan
author_rank: Newbie
timestamp: March 24, 2018, 09:50:01 pm
content: The comment at the top of the script has a link to a repo with tools for working with GW DSOs.https://github.com/OpenWave-GW/OpenWave-200/Looks potentially like the right thing (even if not, I can figure out what Python is doing faster than learning MAtLab).

author: rhb
author_rank: Super Contributor
timestamp: March 25, 2018, 04:38:02 pm
content: Export in LSF and in "Detail CSV" format with 1Kpt taken using the scope calibrator. Convert the LSF to hex, decimal and character format with the Unix utility, od(1). Write a C program to read the things you can identify and go from there. The MATLAB code will give some clues, but IIRC it was a it obtuse.I have a couple of GDS-2000E series scopes. Writing a file convertor was on my to do list, but I've decided to just work on writing FOSS FW for them. I just need a few days without interruption to get started learning Zynq FPGA programming.
How do I read limit switch stroke length? - Page 1
Forum section: electronics / beginners

author: cdevidal
author_rank: Regular Contributor
timestamp: February 28, 2025, 05:17:58 pm
content: How do I interpret stroke length onthis datasheet, is it 0.3mm±0.1 until the switch begins conducting, or is it that distance that the switch physically bottoms out?I intend to place a limit switch at the edge of a PCB. I don't want to stress the switch solder joints so the object needs to hit the edge of the PCB before the switch bottoms out, but not before pressing the switch through its intended length of travel and it begins conducting. If the stroke length on the datasheet measures the distance it must travel before conducting, but it bottoms out much deeper (let's assume at 1mm), I want to position the tip so it is 0.45mm beyond the edge of the PCB, so thatdefinitelyconducts. But if the stroke length is the distance to bottom out, placing it at 0.45mm would stress the solder joints; I should instead position the tip so it is 0.15mm beyond the edge.Which do you think it is?https://www.lcsc.com/datasheet/lcsc_datasheet_2110151630_XKB-Connection-TM-1022-B_C381066.pdf

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 28, 2025, 05:31:29 pm
content: It said contact stroke so it has to move 0.3mm to switch. I am sure it can move significantly more before bottom out.

author: tooki
author_rank: Super Contributor
timestamp: February 28, 2025, 06:11:27 pm
content: I agree with BeBuLamar that 0.3mm is the actuation point.I would suggest, however, choosing a name-brand part that has a proper datasheet. You obviously want a fully-specified part where you know not only the actuation point, but also the full stroke depth.
How do I read this dimension on an enclosure drawing? - Page 1
Forum section: electronics / beginners

author: cdevidal
author_rank: Regular Contributor
timestamp: January 10, 2025, 02:09:47 am
content: Is this saying there are six count holes that are 2.5mm diameter?

author: TimFox
author_rank: Super Contributor
timestamp: January 10, 2025, 02:11:21 am
content: Yes

author: cdevidal
author_rank: Regular Contributor
timestamp: January 10, 2025, 02:16:00 am
content: Thanks, I'd never seen the symbol of an O with a line through it, and didn't know what to search for

author: TimFox
author_rank: Super Contributor
timestamp: January 10, 2025, 02:38:36 am
content: That’s a standard mechanical drawing symbol for diameter.
How do I reattach this type of DSUB connector? - Page 1
Forum section: electronics / beginners

author: matthuszagh
author_rank: Frequent Contributor
timestamp: November 03, 2023, 08:17:19 pm
content: I disconnected the DSUB connector shown in the 2 attached pictures. The sort of "turrets" on the male connector slide into those "slots" on the female connector. I was able to unscrew the nuts on the male connector and then wiggle the connector free. But, how do I reconnect it? Is there a technique? I tried pushing it in and tightening, but the turrets don't make their way back into the slots. Another thought I had is to bend up the bigger slot, slide the turret in and then try to mate the connector. Thoughts?Oh, and knowing the name of this class of connector would be helpful too, to look up more info.

author: ataradov
author_rank: Super Contributor
timestamp: November 03, 2023, 08:52:43 pm
content: I think the intent here is to unscrew or loosen the nuts, then insert the connector and tighten the nuts back.It looks like it was not intended for frequent and quick disconnect.

author: alligatorblues
author_rank: Regular Contributor
timestamp: November 03, 2023, 09:10:36 pm
content: It's a DB-9 serial connector.. But I've only seen one like that on a frequency standard (atomic clock). It looks like it is made to be connected to its mate once, and then left alone. When you say, "slots", are you talking about the screw heads?

author: matthuszagh
author_rank: Frequent Contributor
timestamp: November 03, 2023, 09:16:15 pm
content: Yeah it's an HP 5065A.I figured it out. The silver part slide's side to side (see picture). So you slide it left to insert the connector. This allows the "turrets" to slide through the "slots" and then slide it to the right and tighten the nuts, which locks it into place.I don't think "slots" is the right term. I'm referring to the little holes for the turrets in the silver piece.I think this locking attachment might be called a slide lock.
How do I secure a wire to this Banana Plug? - Page 1
Forum section: electronics / beginners

author: dystopia
author_rank: Newbie
timestamp: January 29, 2021, 11:56:38 pm
content: Hey,I found a couple of banana plugs lying around and can't figure out how to secure a wire to them.Attaching photos - any pointers appreciated!

author: ataradov
author_rank: Super Contributor
timestamp: January 30, 2021, 12:11:26 am
content: It looks like they are designed for soldering. See that notch on the side? That's where you apply solder after the wire is inserted. It can be tricky to solder parts like this, so make sure you have beefy soldering iron tip and plenty of flux.

author: bob91343
author_rank: Super Contributor
timestamp: January 30, 2021, 01:03:29 am
content: I agree.

author: james_s
author_rank: Super Contributor
timestamp: January 30, 2021, 07:00:33 am
content: Yep, I've used some that look just like that before, definitely solder. The bigger hole in the side is so that you can stack them.

author: BravoV
author_rank: Super Contributor
timestamp: January 30, 2021, 07:02:57 am
content: Read this post ->https://www.eevblog.com/forum/beginners/how-to-assemble-banana-plug/msg3286942/#msg3286942
How do I set my avatar and personalized signature? - Page 1
Forum section: electronics / beginners

author: LOTO instruments
author_rank: Newbie
timestamp: February 02, 2023, 07:47:07 am
content: How do I set my avatar and personalized signature?I've searched for a long time, but I can't find a place where I can change my avatar or write my signature. Is it because I have to reach a certain level before I can do these things? thank you very much.

author: pcprogrammer
author_rank: Super Contributor
timestamp: February 02, 2023, 07:53:10 am
content: Select your profile with the "button" in the top line and then select "forum profile". You can set the things you want there.

author: LOTO instruments
author_rank: Newbie
timestamp: February 02, 2023, 09:09:45 am
content: Thank you,it works.
How do I set the time zone for my account here? - Page 1
Forum section: electronics / beginners

author: Sherlock Holmes
author_rank: Frequent Contributor
timestamp: December 04, 2022, 03:16:34 pm
content: Looked everywhere, can't see how to do it, all times are way off for me!

author: Bud
author_rank: Super Contributor
timestamp: December 04, 2022, 03:47:13 pm
content: Profile-Summary-Modify Profile-Look and Layout-Time Offset

author: Sherlock Holmes
author_rank: Frequent Contributor
timestamp: December 04, 2022, 04:21:04 pm
content: Quote from: Bud on December 04, 2022, 03:47:13 pmVery helpful ! much appreciated !

author: Ian.M
author_rank: Super Contributor
timestamp: December 04, 2022, 04:36:27 pm
content: Note that the forum runs natively in UTC time, without any daylight saving adjustments. If you want displayed times to be accurately in your local time and that has daylight saving, you'll have to reset the offset in your profile twice a year when the clocks change.Its still preferable to the situation in the bad old days, when this forum ran on Sidney local time (AEST/AEDT), and many of us had to reset our timezone offset four times a year due to differing daylight saving changeover dates!

author: Bud
author_rank: Super Contributor
timestamp: December 04, 2022, 04:43:26 pm
content: Quote from: Ian.M on December 04, 2022, 04:36:27 pmThat is right. Sherlock-pls take a note of that.