hybridfree/eevblog-posts huggingface dataset:
Need to find this transistor to purchase - Page 1
Forum section: electronics / beginners

author: kenshi
author_rank: Contributor
timestamp: March 26, 2020, 07:58:58 am
content: This is a little embarrassing, but here goes. I bought a Playstation 4 almost half a decade ago because I heard they were going to remake my favorite game of all time, Final Fantasy VII, for the console. Fast forward to last week and they finally come out with a demo, into which I make it about 30 minutes and hear a pop, followed by a black screen and silence. It seems when it came time for my PS4 to serve the primary purpose I bought it for, it decided to die on me.Anyway, this is almost certainly a power supply problem and I want to fix it myself. First I replaced a fuse and two burned resistors and it went from being completely dead to turning on for half a second and turning back off. Now I found another blown fuse that wasn't blown before and a bad MOSFET. (As I recall, it was questionable before, reading a bit off from what I expected, and now it's a dead short even removed from circuit.)Anyway, this thing has Sony numbers on it and I'm quite a beginner at this sort of thing. I think I can find the fuse, but I could use some help finding the transistor on Mouser or some similar site. The number on it is 6R190E6 which of course shows nothing on Mouser but I can find datasheets. What can I look for that would be equivalent? And if there's an easy way to do this, I'd be obliged to know what it is.Thanks.

author: Jwillis
author_rank: Super Contributor
timestamp: March 26, 2020, 08:55:21 am
content: https://www.mouser.com/Search/Refine?Keyword=60R190E6. Try using the the whole numbers off the Data Sheet. Sometimes that helps . But it was an easy search.The prefix Letters are from the package type . IPW is the T0-247 , IPP is the T0-220 , and the IPA is the T0-220 FP . Mouser has 4 variations.

author: kenshi
author_rank: Contributor
timestamp: March 26, 2020, 10:18:03 pm
content: That most certainly helped. Thanks.With that said, the cost of a couple of trannies, fuses, and shipping was about half was an entire power supply costs, so I hope I'm right about this.
need to identify 1 chip - Page 1
Forum section: electronics / beginners

author: aqarwaen
author_rank: Regular Contributor
timestamp: February 26, 2018, 09:24:59 pm
content: so i teardown my old speakers(NOT WORTH REPAIR) and i decided to take pictures to.can anybody tell me what chip it is??i cant seem to find any good info using google..linkhttps://imgur.com/a/0gevh

author: DC1MC
author_rank: Super Contributor
timestamp: February 26, 2018, 09:41:59 pm
content: Literally the first google result:http://thaieasyelec.com/downloads/EFDV308/HXJ8002_Miniature_Audio_Amplifier_Datasheet.pdf
Need to identify a connector - thought it was a Molex Minilock but wrong! - Page 1
Forum section: electronics / beginners

author: akira9000
author_rank: Newbie
timestamp: September 17, 2016, 08:50:44 pm
content: Hi guys, pulling my hair out trying to find a particular kind of connector. I've been playing with an old hardware sampler, connecting current storage (CF, SD cards, SSD drives to 2001 tech) rather than ancient and slow SCSI peripherals and to do the next phase of my experiments I need to make up some cables to allow me to attach some more hardware to the unit's built in power supply.The sampler came with 1 factory spec cable so at least I have something known to compare.One end of the cable is standard Molex hard drive type - easy - the other end I thought was Molex Minilock 4 pole. I was so confident I've bought a bag of them. Unfortunately when I unwrapped them and held them side by side with an existing example, it is definitely not. It's basically much bigger than a Minilock.So, from the images, Molex Minilock 4 pole on the left. Anyone know what the plug on the right is?

author: Monkeh
author_rank: Super Contributor
timestamp: September 17, 2016, 08:57:38 pm
content: JST VH.

author: akira9000
author_rank: Newbie
timestamp: September 17, 2016, 09:12:39 pm
content: You beauty Monkeh! Lightning speed.Many thanks.
Need to identify a fusible resistor - Page 1
Forum section: electronics / beginners

author: MadMaxGR
author_rank: Newbie
timestamp: April 26, 2020, 04:42:48 pm
content: Hello everyone,This is my first post, so please forgive me if I am asking something noob.I want to identify this fusible resistor from a PS4 Power supply. I am sure it is used as fuse because this was confirmed by other technicians on YouTube but I couldn't calculate the correct value. The whole shape is strange too and is not common in the local market to find a replacement easily. I believe it is 16.8Ohm 2% tolerance but I am not sure. I would like a confirmation.Also I would like to know if I can't find the specific value what other alternative values or fuse types can be used?Thank you for your time answering.

author: andy3055
author_rank: Super Contributor
timestamp: April 26, 2020, 06:07:20 pm
content: Check the second post in this thread:https://forums.anandtech.com/threads/weird-fuse-resistor.2469714/

author: Paul Moir
author_rank: Frequent Contributor
timestamp: April 26, 2020, 06:46:57 pm
content: There are five bands there and the 3rd one is silver so it is not a 1% My guess is that the 5th band identifies the particular model of resistor like Bournes does, or it might mean it's a 50ppm temperature coefficient model. Brown-Blue-Silver-Gold = 0.16 ohms 5%. I have no idea about the wattage or specifications, but you could infer them from what it's doing. If it is doing current sensing then the 50ppm might make some sense.

author: MadMaxGR
author_rank: Newbie
timestamp: April 29, 2020, 06:58:35 am
content: after some investigation, I found out that it is "Wirewound Resistor" which is using different color coding? That is very confusing. Do you have any color coding chart for such resistors?

author: MadMaxGR
author_rank: Newbie
timestamp: May 04, 2020, 02:06:35 pm
content: Any help with this please?
Need to identify a part - Page 1
Forum section: electronics / beginners

author: georgedone
author_rank: Contributor
timestamp: July 20, 2020, 04:16:51 pm
content: Hi !On a PC motherboard I need to identify the components marked on silkscreen with TC19, TC18, TC17 and on the components themselves with "330".They are 2 pin components in parallel and seem to be polarized. because they have a band mark at one end. One of them is in short (will neet to remove them one by one to figure out which.I presume they are tantalum capacitors (hence the TC on silkscreen) ?or perhaps some temperature coeficient parts (thermistors) but no sense to install that many in parallel so I put my monies on capacitors.Anyone could let me know what they are ?

author: simonboydfoley
author_rank: Contributor
timestamp: July 20, 2020, 04:31:47 pm
content: That's too big a via for a capacitor ... It's designed to take a bit of current .. is it not a voltage regulator ?

author: georgedone
author_rank: Contributor
timestamp: July 20, 2020, 04:48:12 pm
content: Thanks for the reply. I am not sure if voltage regulators exist with only 2 pins. LDOs have 3 pins or more, I believe. Further, there are some pads unpopulated, it would be consistent with a number of capacitors installed in parallel of which not all proved to be necessary in the end. The vias are vor vCore for a mobile CPU so which I expect to be about 0.965Volts there are probably some serious Amps (30?), having capacitors installed nearby on thick vias would help.

author: Twoflower
author_rank: Frequent Contributor
timestamp: July 20, 2020, 05:02:37 pm
content: Probably a 330µF solid electrolytic cap with low ESR. I think that's this series:https://industrial.panasonic.com/cdbs/www-data/pdf/ABE0000/ABE0000C61.pdfThe letter d denotes the maximum voltage (d = 2V)Quote from: simonboydfoley on July 20, 2020, 04:31:47 pmEdit:Why do you think that's too big for a Cap? There are even bigger SMD caps (ceramic or electrolytic) out there.I think I misunderstood that. Yes there lots of Vias to reduce the resistance of the plane change. But nothing unusual. They are needed to minimize the ripple as much as possible. That's also the reason for the low ESR caps (in this case the ESR = 3m\$\Omega\$).
Need to measure Phone battery drain over time - Page 1
Forum section: electronics / beginners

author: mcBontempi
author_rank: Newbie
timestamp: September 01, 2020, 12:08:38 pm
content: Hello people.Im an app developer and we are building an app that uses the gps to keep the app running and send a users location to the server, when the gps position is received we use the time slice to do a bit of computation and send the position back.We are unsurprisingly having battery issues, we need to be able to fine tune this and get some exact numbers of which parts are using the most power.We will be able to comment out parts of the code and do successive runs to be able to compare.What we need (I think) is a bench supply with constant voltage, and then have the supply log the amp usage (preferably a few times a second)having an overall amp hour result would be useful.As you can tell I know a small amount of electronics, but seriously not much so I could do with someone recommending some hardware and any best practices for doing this sort of analysis.Apple do provide tools for this, but its really abstracted and rather useless.I know how to pull the battery out of the iPhone and connect a supply directly up so we can power directly. I just need advice on the hardware and as ive said any tips.thank you in advance, id really appreciate your help her as the client is having a breakdown!

author: Heisen
author_rank: Contributor
timestamp: September 01, 2020, 12:38:53 pm
content: Maybe this is what you want. Power cable w103

author: ledtester
author_rank: Super Contributor
timestamp: September 01, 2020, 10:26:02 pm
content: Well, Dave just did a presentation on the BattLab One battery life estimator tool from Bluebird Labs:https://www.eevblog.com/forum/blog/eevblog-1331-battlab-one-review/Of course, this measures power consumption from the entire phone. Haven't done any IOS development, but it would seem likely that the Apple instrumentation code would be able to isolate power consumption at the app level.

author: mcBontempi
author_rank: Newbie
timestamp: September 03, 2020, 03:29:07 pm
content: we have already used the apple tools, but they are a little abstracted.its more a case that we need the hardware to measure amps drawn every second or so.the problem is that the app is for child safety and needs to be run overnight, so we need to stop the battery draining.I did this on a project once before with just a bench supply, but that was just to see the current draw at a particular time, rather than over time..Daren...
Need USB-to-UART adapter with DTR and RTS headers - Page 1
Forum section: electronics / beginners

author: Peabody
author_rank: Super Contributor
timestamp: March 01, 2019, 03:27:57 pm
content: This would be for BSL flashing of TI MSP430 processors. I need Tx, Rx, DTR, RTS, Ground, and 3.3V. The lines need to be 3.3V.I've searched Ebay, but can't find anything. The closest I found was this, which could be made to work, but only after some modification:https://www.ebay.com/itm/182603235304The standard FTDI cable/adapter has CTS, which is not what's needed.Does anyone know of such an adapter, or a cable?

author: rstofer
author_rank: Super Contributor
timestamp: March 01, 2019, 04:18:58 pm
content: https://www.sparkfun.com/products/13263There is a jumper to select 5V versus 3.3V - see the schematic under the Documents tabThere will be a small glitch with DTR. It is used to reset boards like the Arduino and, therefore, it has a FET and a couple of resistors. These could be removed to get a clean DTR. Again, see the schematic.

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 01, 2019, 05:19:07 pm
content: Buy one with headers for all ftdi pins available and a level converter, you'll have it all for any requirementEnvoyé de mon iPad en utilisant Tapatalk

author: tsman
author_rank: Frequent Contributor
timestamp: March 01, 2019, 05:51:06 pm
content: If you want a fancy isolated dongle then pylo'smuArtlooks good. If you've got a TI Launchpad lying around then you can use that for BSL. Otherwise do what the others have already mentioned.
Need very time to see wave shape on oscilloscope - Page 1
Forum section: electronics / beginners

author: Jasonbit
author_rank: Regular Contributor
timestamp: August 07, 2018, 12:55:26 am
content: Hello folks,I have this Picassohttps://snag.gy/hme2xG.jpgThe purpose of capacitor it reduce or eliminate bouncing the switch end the user wide button. On my oscilloscope I can see the effects of the capacitor but I don't know well I should parameter the equipment. On this print screens,https://snag.gy/KIcTe6.jpgandhttps://snag.gy/5ApnSw.jpgyou can see the wave signal with capacitor 10uF and without capacitor. But to achieve this signal wave I need parameter time/div in 1 second per time. I need wait a second to can see have shape each time the button is pressed.I am configuration the equipment well?

author: JS
author_rank: Frequent Contributor
timestamp: August 07, 2018, 01:31:49 am
content: What are you reading the switch with? Are you working with a low power device?The values seems off, 10k and 10µF is slow, what you are seeing is a fast discharge (charge actually, the cap is discharged when going high and charged once the switch is released) till you are under the LED conduction voltage and then it keeps discharging with the 10k alone, that's why the shape isn't a simple time constant exponential discharge.You can get away using a smaller cap, or a smaller resistor, but that resistor will chew more energy while the button is pressed, so if you are working with a low power device a smaller cap is better, but the LED could charge it too fast. You want the charge to be slow enough so the bouncing is faster than the discharge of the cap. I've got away with 4.7nF last week but it only connected a reset pin on a µC, with the LED that's likely to be too small.Get a closer picture from your scope without the cap so you see the actual bouncing times, to get an idea, the longer one we call 'bounce time'. Then choose a time constant, 5 times longer than the 'bounce time' could be a ball park. Then choose a cap so your LED resistor/cap time constant match that. To finis the design pick a resistor that ends that discharge fast enough so you are happy with it, say 10 times the other resistor so you get 50 'bounce times' to 99% discharge.JS

author: alsetalokin4017
author_rank: Super Contributor
timestamp: August 07, 2018, 10:58:05 am
content: Quote from: Jasonbit on August 07, 2018, 12:55:26 amUse the Horizontal Position control to move the trigger point over to the left edge of the screen trace area. Use Trigger Level control to set trigger level a little higher than 0.Also try using the Single Shot sweep mode. Get ready, push SINGLE button on scope top right, then push your "user wide" button. Sweep should start and run one screen then stop.
Neat video on power dist transformers - Page 1
Forum section: electronics / beginners

author: paulca
author_rank: Super Contributor
timestamp: July 31, 2024, 03:47:52 pm
content: https://youtu.be/96Vekm8Ws4U

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 31, 2024, 05:40:09 pm
content: The other day I came across a railroad intersection where the gates had already closed.Turned off the engine while waiting the lumbering train to pass.It was a short train, and it carried an absolutely massive transformer in a special rail car known as the Schnabel car.Something similar to this;
Needed a P-FET selection suggestion - Page 1
Forum section: electronics / beginners

author: sani
author_rank: Newbie
timestamp: June 06, 2023, 05:59:39 pm
content: Hello Everyone,I want to reproduce a circuit that I provided in the attachment.But it looks like I chose the wrong P channel mosfet.I use IRF9540NPBF (here is the datasheet:https://www.infineon.com/dgdl/irf9540npbf.pdf?fileId=5546d462533600a401535611cfa21dc8) and it never turns offSo, do I correctly understand that VgsTh from -2 to -4 means that 5V(gates) - 8.4V(source) = -3.4V should turn off the mosfet, so there won't be a connection between batteries and the DC-DC?Why this does not happen?What am I doing wrong?Could anyone correct me if I am wrong?Also, if someone may suggest a good mosfet for me or tell me how to find a mosfet model that could solve my goal, it would be great.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 07, 2023, 05:11:51 pm
content: You've reversed drain and source, all current is flowing unimpeded through the body diode.Vgs(th) is the voltage at which the mosfet turns on to some but not its full extents,

author: sani
author_rank: Newbie
timestamp: June 08, 2023, 07:37:46 am
content: Thank you for your response.I am not sure is it correctly drawn on the circuit. But I use the image from the attachment to define the mosfet pin meaning and connected the Source pin(3rd one) to the battery BMS (8.4V), the Draine(2nd one) to the DC-DC and The Gate pin(1st one) to the 5v source. Additionally, I use 10k resistor for connecting the Gate pin to GND.As a result, I always receive 8.4V on the DC-DC input no matter is 5v connected or not (Is the connection right?I am afraid that 5v is not enough to close the mosfet. Will the mosfet be closed if I use some step-up module for the gate pin, e.g. use 9v for the gate?Also, I tried to fin another mosfet with the min Vgs(th) = -4v. I think maybe, in this case, the 5V on the gate will manage to close the mosfet.But I haven't found anyone(

author: Damianos
author_rank: Frequent Contributor
timestamp: June 10, 2023, 05:14:40 am
content: The numbering of the pins between the datasheet and the software that you use does not match! There are different packages and types of transistors with various pinouts, check it and correct the drawing.The resistor should be connected between gate and source, so the transistor remains off without a control signal (Vgs=0).The control signal (+5V in the schematic) must come from an open drain/collector circuit, for the Vgsto operate between zero and (-)VBATT. If it cannot be configured, use an additional transistor to implement it (this will invert the signal).
Needing a clean 5v reg - Page 1
Forum section: electronics / beginners

author: David97
author_rank: Contributor
timestamp: September 13, 2016, 06:17:02 am
content: Hi everyone. Working on building a small video receiver to use with FPV models.Ive been playing with a rx5808 module. First I was using a arduino board to get 5v power from for testing. But this was not giving me enough current. The regulator was getting hot.I measured the current to be around 200mA. I was dropping the voltage from a 12.6V battery.That's (12.6-5)*0.2=1.5Watt, that's probably why it was getting hot.So I took a cheap Chinese, no name, buck converter from my box of parts, and hooked that into it. Problem was that even with a 470uf cap, was producing noise (I think, I dont have a scope). Anyway the video sucked compared to my other receiver (store bought), which I'm certain uses the same module.So cant definativley prove that that was the problem without a scope, but not going to want to run the cheap anonymous buck regulator from china anyway. I know having low ripple is important with this project anyway.So weather or not that was the problem, I need a new 5v regulator.Needing something with low ripple, has a input range of 6V-12.6V, and can provide the necessary current.Switching would be nice, but not necessary, since I know switching regs tend to produce more noise.Thanks for your're help! Sorry for the noobie nature of this question

author: David97
author_rank: Contributor
timestamp: September 13, 2016, 06:28:59 am
content: Discussions on this thread about a similar project have led me to believe that this would be a good optionhttp://www.rcgroups.com/forums/showthread.php?t=2477752&page=11http://nz.rs-online.com/web/p/switching-regulators/6664379/

author: homebrew
author_rank: Frequent Contributor
timestamp: September 13, 2016, 05:01:48 pm
content: Hm, why not using a good old 7805 linear regulator in a TO220 case?200mA doesn't seem to be a big deal - just select a proper heat sink.Add two 100nF bypass caps (input and output) and a 470uF bulk capacitor at the input and another 100uF on the output and you should be fine. A 1N400X diode as reverse bias protection and another one to protect from reverse polarity.Adding a fuse would make it even more safe.However, this won't work anymore with 6V. You probably need something around 8V to get this working ...

author: JPortici
author_rank: Super Contributor
timestamp: September 13, 2016, 06:34:23 pm
content: +1i will be using the same configuration in a future project. i am basically a noob in smps but it wasn't hard to achieve good-ish performance, maybe with poor efficiency but a rather clean signalblueskull might correct me but i wouldn't go crazy high in switching frequency as LDO PSSR usually become rather poor over 10-20 kHz
needing to "delay" a signal based on a clock-like one - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: December 10, 2021, 12:58:48 pm
content: Hi.I am experimenting with various stuff and I have an oscillator (currently made from a 555 timer) running at a slow speed, outputting its rectangular waveform.Now, supposing to have this kind of clock (perhaps sqw this time) running at 0.3 - 5 Hz, I would like to derive a signal from it so that it's... 90° out of phase I think: I mean that when one sqw transitions the other is in the middle point of its steady state.Well I don't know whether I'm stupid or just inexperienced (or both) but I have no idea on how to make that happen.any suggestions?thanks

author: dmills
author_rank: Super Contributor
timestamp: December 10, 2021, 01:33:19 pm
content: Run your clock at 4 times the rate you want and then use a pair of flipflops configured as a johnson ring counter to produce a two phase output?

author: gcewing
author_rank: Regular Contributor
timestamp: December 10, 2021, 02:11:02 pm
content: Generate a clock at twice the desired frequency and use a flip flop to divide it by 2. Use a second flip flop triggered on the opposite edge of the clock to delay the output of the first one.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 10, 2021, 06:07:24 pm
content: Like this:or with fewer parts this:

author: Benta
author_rank: Super Contributor
timestamp: December 10, 2021, 07:09:11 pm
content: Triggering on both edges of a clock signal is bad design practice, as there's no guarantee that it has a duty cycle of exactly 50%. This limits your circuit flexibiliy seriously.Using a x4 clock is the way to go. Whether it's positive or negative edge triggered doesn't matter.

author: Moriambar
author_rank: Unknown
timestamp: December 10, 2021, 07:45:27 pm
content: thanks to all. I don't understand what to do with the 4x clock.btw I'll try the circuits during the weekend and see what's what.

author: Benta
author_rank: Super Contributor
timestamp: December 10, 2021, 10:01:53 pm
content: Quote from: Moriambar on December 10, 2021, 07:45:27 pmNo worry.I think that what you're trying to achieve is a signal as shown in the upper two traces in the attached picture. Am I right?In that case, the graph shows why you need a 4x clock to generate a 90 degrees shift. You need four active transitions per full output cycle.The lower two traces show the clock inputs, one with a 50% duty cycle, the other with a different one. The point is, that the clock edge is the reference point, here marked with a dot.

author: Moriambar
author_rank: Unknown
timestamp: December 12, 2021, 08:11:24 pm
content: Quote from: Benta on December 10, 2021, 10:01:53 pmCool thanks!

author: Benta
author_rank: Super Contributor
timestamp: December 12, 2021, 10:03:56 pm
content: This should work:
Neep EEPROM dump for APC SMT750i UPS - Page 1
Forum section: electronics / beginners

author: Abrarahmad000
author_rank: Newbie
timestamp: April 21, 2023, 01:05:32 am
content: Hello everyone,I was updating the firmware of an Apc ups smt750i (LCD model). Suddenly power went out and the PC I was using to update firmware turned off. Now the firmware in UPS is corrupt and it only shows a blank LCD and continous beep. Many other users had same problem while updating firmware.Now according to professionals and APC forums, The EEPROM in UPS needs to be reprogrammed, but they dont have it's dump available. So I need its dump to reprogram it.Thanks in advance.
How do I create a negative 3V3 power supply from a 1 cell lipo? - Page 1
Forum section: electronics / beginners

author: Commander Cloud
author_rank: Newbie
timestamp: October 25, 2019, 06:53:48 pm
content: Hello all,I am a newbie teen designing a PCB for a project with a display, and the display I am set on using needs a -3V3 power source. How can I best and most efficiently create this power rail from a 1 cell lipo? (It is already protected and regulated to 3V3, fyi). Thanks in advance,CommanderCloud.

author: madires
author_rank: Super Contributor
timestamp: October 25, 2019, 07:36:07 pm
content: By an inverting DC/DC converter.

author: artag
author_rank: Super Contributor
timestamp: October 25, 2019, 09:03:17 pm
content: For the simple case of inverting a power rail (and if the current demand is small), you might be able to use a 7660http://www.ti.com/product/TL7660

author: tooki
author_rank: Super Contributor
timestamp: October 25, 2019, 09:05:56 pm
content: If it's an LCD that just needs the negative supply for the contrast pin, then you should also be able to use a cheap ICL7660 chip. Easy to work with and inexpensive, but limited to very, very small amounts of current. (Many 3.3V 1602 LCDs, as well as some large or extended-temperature versions, even at 5V, use an ICL7660 precisely to create the LCD contrast voltage.)Edit: heh, great minds think alike, artag!

author: iMo
author_rank: Super Contributor
timestamp: October 26, 2019, 05:58:28 pm
content: http://elm-chan.org/docs/lcd/lcd3v.html
Negative ground voltage from a battery  - Page 1
Forum section: electronics / beginners

author: Mandarin47
author_rank: Contributor
timestamp: June 08, 2020, 01:37:01 pm
content: Hi all, I have very little experience with electronics but I have a faulty trailer module for a car that is supposed to illuminate lights on a trailer. Most of the lights work but the fog lights don't. The trailer works with other cars. I have tried 2 trailers and the fog lights don't work on either. I don't have a circuit diagram for the module so I have just had to go through it to see if there's anything obvious.Anyway, while testing it I found that under certain conditions the fog lights will illuminate (an indicator light has to have been illuminated before the fog light) but there is a negative voltage at the ground of some components around the relay. Its negative 22-38mv. I would have assumed that it would be 0v. Is this normal or could that be a symptom of the fault? The same points are 0v when the fog light is not illuminated.

author: SmokedComponent
author_rank: Regular Contributor
timestamp: June 08, 2020, 03:44:27 pm
content: This is normal, you are measuring voltage drop in the circuit (between your probes) caused by the current of the lights on and resistance of PCB traces and wiring. Tiny drop like that probably isn't causing any problems.

author: Mandarin47
author_rank: Contributor
timestamp: June 08, 2020, 10:21:20 pm
content: Hi, thanks very much for your help.
Negative ohms reading  - Page 1
Forum section: electronics / beginners

author: wertyu
author_rank: Contributor
timestamp: May 17, 2022, 12:30:53 pm
content: I was just practice testing a good PSU as trying to learn more on electronics , when testing a little chip i notices the negative sign pop up on some pins. What is this reading ?Thanks in advance

author: artag
author_rank: Super Contributor
timestamp: May 17, 2022, 12:33:00 pm
content: It's reading that there's some residual voltage on the pins you're measuring. Swap the probes around and it will probably read positive. Resistance measurements aren't valid when the circuit is powered, or has capacitors in it which are not discharged.Negative resistance does exist but you can't measure it with an ohmmeter.
Negative output from a boost converter - Page 1
Forum section: electronics / beginners

author: mcdesca
author_rank: Contributor
timestamp: November 08, 2015, 10:09:37 am
content: Hello,Is it possible to obtain a negative output from a dc/dc boost converter by just reversing the output rails? Why is then an inverter mostly used in LCD bias?Thanks.Best,

author: ruffy91
author_rank: Regular Contributor
timestamp: November 08, 2015, 11:45:49 am
content: Yes it is possible. But if it is not galvanically isolated you will not have GND as common but the positive DC/DC output and GND will be your negative output.
Negative Polarity Relay - Page 1
Forum section: electronics / beginners

author: wiredwrx
author_rank: Contributor
timestamp: July 03, 2020, 06:23:09 pm
content: Hello,I have a need for an SMA Relay, so have been searching the regular cheap sources (eBay) and found one that seems to fit the bill.eBay auction: #https://www.ebay.com/itm/1-QTY-Ducommun-RF-Relay-SMA-DC-to-26-5-GHz-12V-DC-Improved-2SE1T11JB-latch-rela/352978635373?hash=item522f2a8a6d:g:lLgAAOSwEDFeUBTxI searched for a spec sheet/wiring information, and found the attached pdf. Breaking down the model number, it indicates the relay is a Negative Polarity unit. Does that mean that the "common" should be positive, and to activate the coil/relay I must apply a negative to the other pins/wires? Certainly, simply grounding pins to activate the relay won't work without a positive (connected to the common), correct?Thanks

author: Renate
author_rank: Super Contributor
timestamp: July 05, 2020, 06:48:49 pm
content: My take on this is that the ground/common/return is negative.There is a positive supply pin.The two control pins usenegative logic.Grounding one of these pins for a second will latch it in that position.
Negative supply from oscilator  - Page 1
Forum section: electronics / beginners

author: DarkZero
author_rank: Regular Contributor
timestamp: January 07, 2014, 11:02:55 am
content: hello all!Recently i needed a negative power supply so my "lab power supply" can go to 0V, so i built a sine oscillator out of 2 op-amp's decoupled it with a capacitor and rectified the negative part with a diode but i got strange results both in simulation and on scope so i googled some internet schematics and found out that there should be a diode rectifying the positive part to ground after decoupling cap. usually when do this with transformer works fine without that diode.so yes my question is a newbie one but whats the purpose of that diode if someone can explain.thx in advance

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 07, 2014, 01:04:43 pm
content: Without the diode to ground the capacitor will charge to 5 (- 0.7 diode drop) volt so that at the left side of the cap you will end up with a sinus from 0 to 10 volt, and there's no way to make a negative voltage from that. You can measure that by probing the point where the diode to ground should be, see the attachment. Also, you should have a load and another cap at the left.

author: Bored@Work
author_rank: Super Contributor
timestamp: January 07, 2014, 06:18:03 pm
content: For more details, Dave made a video about this. Sorry, don't remember the title.

author: Alana
author_rank: Frequent Contributor
timestamp: January 07, 2014, 11:32:20 pm
content: I think its this onehttp://www.eevblog.com/2013/05/10/eevblog-469-cockcroft-walton-multiplier/

author: DarkZero
author_rank: Regular Contributor
timestamp: January 08, 2014, 07:59:40 pm
content: thx for all replies ill go check that video maybe ill get it how it works
Negative trigger relay backfeed - Page 1
Forum section: electronics / beginners

author: ZeroAviation
author_rank: Contributor
timestamp: July 23, 2018, 02:47:59 pm
content: Hi all,Is there a simple way to prevent backfeed on a traditional relay triggered by GND? Entire circuit is 12V.I have tried a 1N4004 tied over the coil (85,86), that didn’t work. I also tried the same diode (in both polarities) on negative wire only with no success.The only thing that dropped the voltage down was a 1K resistor tied from GND to the negative of the coil. At this point though, it is drawing (small) unnecessary current.Any thoughts on that issue?Also, would the solution be able to be used whether the relay was positive or negative triggered? I want my project to be versatile to be triggered either way, without the voltage backfeed.Thanks in advance

author: Zero999
author_rank: Super Contributor
timestamp: July 23, 2018, 06:34:04 pm
content: What do you mean by back-feed?A diode in reverse parallel will get rid of most of the back-EMF. If you're worried about the last 0.6V, then add another diode in series.

author: ZeroAviation
author_rank: Contributor
timestamp: July 23, 2018, 08:43:38 pm
content: When I connect one side of the relay coil to positive 12V, and then measure the negative side of the coil to GND, I get 12V. The 12V is getting fed through the relay, and causes an issue with the circuit.A diode in series prevents the back voltage, but doesn't allow powering of the coil

author: HB9EVI
author_rank: Frequent Contributor
timestamp: July 23, 2018, 09:00:50 pm
content: hmm, I'm trying to get the clue, but...what about a schematic? of course the positive rail voltage appears on the other end of the coil; it's not so high resistive, that it wouldn't

author: Zero999
author_rank: Super Contributor
timestamp: July 24, 2018, 09:20:01 am
content: Quote from: ZeroAviation on July 23, 2018, 08:43:38 pmThat's what you should expect to happen. The multimeter has an impedance of around 10 million Ohms and the relay coil an impedance of no more than a few thousand Ohms, so if they're connected in series, nearly all of the voltage will be dropped across the meter.QuoteIt sounds like you're connecting it up incorrectly. If the circuit controlling the relay, is also switching other loads, then they should be in parallel with the relay, not series.More information is required to give a definitive answer. Please post a schematic.
negative voltage conversion - Page 1
Forum section: electronics / beginners

author: sagnikbasu
author_rank: Contributor
timestamp: January 26, 2017, 06:11:00 am
content: How can we convert -3 Volt to -8 Volt ,without using any inductors ?

author: Skimask
author_rank: Super Contributor
timestamp: January 26, 2017, 06:22:01 am
content: Move your ground up 5v.

author: David Hess
author_rank: Super Contributor
timestamp: January 26, 2017, 06:27:20 am
content: A charge pump can do that at low currents. At even lower currents, a photo voltaic driver for a MOSFET can do it.Why do you have a restriction of no inductors?
Negative voltage in circuit - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 12, 2015, 10:11:48 am
content: I need negative voltage in my circuit with common ground wrt positive voltage1. One option is to generate negative supply by placing a full- bridhe & then using 7905.It includes lots of extra components to be used.2. Another option is to use TC7660. Simple to use & works good. Only problem is its output voltage falls with current. For a load current of -10 mA and a supply voltage of +5V, the output voltage would be -4.3V.3.I need to generate regulated -5V,-2.5V&-1.8V4.Any other way to do that?

author: kg4arn
author_rank: Unknown
timestamp: February 12, 2015, 10:31:51 am
content: What is the current demand for each negative supply?

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 12, 2015, 11:02:31 am
content: 50mA max.

author: electr_peter
author_rank: Unknown
timestamp: February 12, 2015, 04:11:53 pm
content: How do you power your circuit? If you have spare transformer tap, use that.Other option would be inverting DC/DC voltage inverter. There are also isolated DC/DC 5V in/5V out converters (at a higher cost of course).

author: IanB
author_rank: Super Contributor
timestamp: February 12, 2015, 05:25:11 pm
content: If you are powering your circuit with low voltage AC from a transformer then can't you just rig up a voltage inverting leg off the AC source? (I think it only needs a couple of diodes and a couple of capacitors. Both are cheap jelly-bean components.)

author: mariush
author_rank: Super Contributor
timestamp: February 12, 2015, 05:42:46 pm
content: If you don't want to complicate your life with multiple taps on transformer, you could also resort to using a cheap mc34063 switching regulator in inverting mode :http://www.intusoft.com/onsemipdfs/AN920-D.pdfThere's a software on Sourceforge which makes the math super easy:http://sourceforge.net/projects/mc34063uc/
Negative voltage, just want to be 100% before spending money. - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 06, 2020, 04:15:22 am
content: Hi,I have the powermod chassis in the mail and I want to order this module for it, to generate negative voltages:https://www.digikey.com.au/product-detail/en/XGE/633-1300-ND/4506602/?itemSeq=3255531915-28V 5A 120W AC DCI'm sure this powermod system is isolated.I just want to be 100% that if I need say -5, I set it to 5v and I connect it like so:Device Powermod+ -- +Newbie question but I just want to be sure before I spend the cash.Thanks.Richard

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 06, 2020, 10:52:25 pm
content: Yes, as it is an AC-DC convertor with isolated output - you can use it to make negative voltage. It is the usual way.You only have to check if there is a need to put anti-parallel protective diodes to power supply outputs. I would rather add ones to not guess.

author: WattsThat
author_rank: Frequent Contributor
timestamp: May 06, 2020, 11:30:26 pm
content: I hope you understand that at 5 volts output, that’s a 25 watt output supply. So, at roughly $500 AU for a single output module and chassis, that’s $20 per watt.I could think a few more points and concerns but since you’ve given us zero idea what you intend to do with this supply, there’s not much more to say at this point other than damn, that’s a lot of money (for a 5v power supply).
Negative voltage on BLDC Hall Effect output - Page 1
Forum section: electronics / beginners

author: Tin Duc Vo
author_rank: Contributor
timestamp: June 17, 2016, 08:54:29 pm
content: Hey everyone,I was wondering if anyone knew why the Hall Effect sensor output of a three phase BLDC would go negative? The motor I am using has a Hall Effect module with 3 signals + power and ground. I hooked it up like in the picture below. For some reason, all of the signals spike to some negative voltage when they're not supposed to transition and then decay back to zero. I can't have this because it would destroy the other components. If anyone could help me with figuring out why this output is going negative, that would be lovely. Thank you.

author: uncle_bob
author_rank: Unknown
timestamp: June 18, 2016, 06:52:48 pm
content: HiMost likely reason - because the sensor is grounded to the motor frame and that ground is not the same as the ground in your measuring setup.Bob

author: Tin Duc Vo
author_rank: Contributor
timestamp: June 20, 2016, 01:09:39 pm
content: Thank you, Uncle Bob. I actually did not ground the case of the sensor to the circuit ground because I did not think that would be so crucial, but I will try that now. Honestly, I do not understand why that would cause the circuit to do this, but if it works, I will report back. If it does not work, I will also report back ... but with a nice picture.
negative voltage threshold detector - Page 1
Forum section: electronics / beginners

author: bertjeivens
author_rank: Newbie
timestamp: February 28, 2015, 06:18:16 pm
content: Hello all,I'm learning electronics by doing a small project but i have hit a small bump.I need to simulate a valve which is controller by a intelligent remote controller. At work we are going to test 15 of these controllers at the same time. To avoid to have to install 15 valves I would like to simulate them.I have 3 elements that are locally on the valve 1*10k pot and 2 piezo electro valves for the compressed air.So all i need to do is detect the pulses on the piezo elements to check wether the controller wants to open or close and then use a digital pot to simulate the position of the valve accordingly.I thought I had it figured out to detect the pulses from the controller (+22V) by clipping but now that i'm doing some testing I noticed it are actually pulses of +22V or -22V depending on the direction. I wonder how i could detect the negative voltage on an arduino, I just want to use a DI?I was thinking about using a optocoupler and using the ground connection of the digital pot but as i dont know how the controller exactly works i'm afraid of sending too much current there.I dont want the solution but just a pointer to the best route to take. I have the feeling I'm overlooking something abvious.Thanks,Bert

author: Zero999
author_rank: Super Contributor
timestamp: February 28, 2015, 08:44:02 pm
content: There are many ways to detect pulses below the power supply rail.You could connect a potential divider between the MCU's +V pin, the input and the signal you're detecting. With a +V of 5V, a divider ratio of five, will mean the MCU input will drop below 0V when the input falls below -20V. Don't worry if the MCU input goes slightly below 0V, the protection diodes will prevent any damage, providing the current is low enough.
Negative Voltage vs Two Floating Supplies - Page 1
Forum section: electronics / beginners

author: joegtp
author_rank: Contributor
timestamp: April 22, 2013, 06:25:02 pm
content: What are the advantages of using something like an LM337 to generate negative voltage verses building two floating supplies and hooking them up in series and using the center point as the ground reference (such as the Mastech HY3005F-3)?

author: c4757p
author_rank: Super Contributor
timestamp: April 22, 2013, 06:31:54 pm
content: LM337 does not generate a negative voltage in the same way that LM317 does not generate a positive voltage.

author: c4757p
author_rank: Super Contributor
timestamp: April 22, 2013, 06:39:16 pm
content: A device thatdoesgenerate a negative voltage (like a buck-boost converter) has one huge advantage - you only need one DC power input.

author: joegtp
author_rank: Contributor
timestamp: April 22, 2013, 06:44:52 pm
content: Quote from: c4757p on April 22, 2013, 06:31:54 pmSorry. By generate I meant to say regulate.

author: Unknown
author_rank: Unknown
timestamp: April 22, 2013, 08:56:39 pm
content: There is no problem doing that, so long as each of the two secondary windings of the transformer are independent and floating... however, any virtual ground DC, between each floating supply if made to a metal chassis, with a mains earth; should then be your common ground and interconnections for signal-screen-cable returns.

author: Harvs
author_rank: Super Contributor
timestamp: April 23, 2013, 12:46:24 am
content: There's no difference if you assume you're only ever going to need a positive and negative rail.But I use my floating rails to generate different things all the time. Some times I need two positive rails with a common ground, sometimes I need one rail to power the input to something, and another rail to float on top of some other point in the circuit that has no defined reference to the other rail. It just adds flexibility.Often this doesn't come from a circuit that would have that in normal operation once it's fully built, but rather, if you're trying out a concept and don't want to put hours into building a multi-rail supply just to see if the concept is going to work.
Negative Voltage/Current? - Page 1
Forum section: electronics / beginners

author: SimplyElectronics
author_rank: Contributor
timestamp: August 30, 2016, 07:07:35 pm
content: Hi Guys,I am at another hurdle :/ I am struggling to get my head around the concept of negative voltage/current.Watch this quick video to see what I am looking at:I know once I wrap my head around this I will get it. But this concept is difficult for me to grasp.Basically, what I expected was when I close the switch, the voltage across the cap would read 12v and when viewing current, I expected a spike of +25mA rather than -25mA and -12v that I actually saw.Could someone possibly help a newbie understand why this happens?Thank you in advance!

author: madires
author_rank: Super Contributor
timestamp: August 30, 2016, 07:29:16 pm
content: I don't know that software, but I assume that the green arrows are the currents. And since the sum of all currents in a junction is zero (Kirchhoff's laws), and the green arrows both point away from the switch, one has to be negative. Or in other words, the direction of the green arrow at the battery is the wong way around. But when you consider the "wrong" direction and the negative current, everything is perfectly fine. I hope this isn't too confusing.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: August 30, 2016, 08:10:20 pm
content: Looks like the voltmeter is attached "backwards"--it's + terminal is going to the battery's - terminal--so that's where the -12V is coming from.It's not obvious to me where the current measurement is coming from. There's two green arrows on there. One of them is facing opposite the direction that current will flow, and the other is pointing in the direction that current will flow. I suspect your negative current is a similar issue to the negative voltage; you're measuring it with something that thinks "positive current" is in the opposite direction from how current is flowing in the circuit. (Positive current flows from higher voltages to lower voltages.)Voltage measurements are always relative. Strictly speaking, you can't point at a node and say "that's 12V". You say "that's 12V higher than this node over here". If you do just say "That's 12V", you are referencing some previously agreed-upon 0V node. Current measurements do typically have a fixed 0 (0 coulombs/s) but the direction is still arbitrary, so the sign will be based on which direction you measure it in.

author: Nexo
author_rank: Regular Contributor
timestamp: August 31, 2016, 05:26:24 am
content: QuoteI also so that and, for me, is the only explanation to why would the voltage measurement is negative although I have one question, how is this software measuring the current? I mean, the voltage measurement is quite obvious, it's connected in parallel to the CAP but I don't see a amp-meter connected in series within the circuit. Am I missing something?Thanks in advance.

author: SimplyElectronics
author_rank: Contributor
timestamp: August 31, 2016, 06:08:51 pm
content: Turns out the software was running in electron flow instead of conventional current!Thanks for sparking the thought!
Negative/positive ground solar charge controller topology? - Page 1
Forum section: electronics / beginners

author: V_King
author_rank: Regular Contributor
timestamp: May 21, 2018, 07:04:46 am
content: Hi,I am building myself a small PV solar setup to charge deep cycle batteries on my boat. After a while of trying to figure out Chinese charge controller specification intricacies I have a question in regards to positive ground solar MPPT charge controllers.The market is seem to be flooded with positive ground MPPT solar charge controllers and the same controllers with negative ground are usually charged more money. It got me wondering how much do those controllers differ? Is it just a matter or tying either positive or negative rail from PCB to the chassis or should I expect more fundamental differences to the PCB layout and design? Please don't forget we are talking about the Chinesse solar charge controller which is same model, just positive or negative ground model designation.Thanks,