hybridfree/eevblog-posts huggingface dataset:
How the 110/220VAC switch on an SMPS work - Page 1
Forum section: electronics / projects

author: CoffinDodger
author_rank: Regular Contributor
timestamp: February 03, 2020, 11:52:04 pm
content: Been having a little trouble looking this one up since. All my searches just bring up topics about plugging 110 VAC devices/appliances into 220 VAC.So the source voltage selector switch on my little Chinese SMPS. Would like to get an idea as to how exactly it works as it looks like it's tying the neutral between the filter caps on the DC side of the rectifier. I'm assuming the Caps act like a voltage divider for the 60hz 120VAC and this some how biases/bumps the DC side so the circuit thinks it has 220VAC. Not really sure but I drew up a circuit based on what I see and probing.It doesn't help that i'm trying to repair the little guy since I fat probed it a while back. I was trying to get a measurement of VCC on the switching regulator IC and my DMM probe lipped and shorted VCC to OUT and blew open the whole switching circuit. I've replaced everything i've found to be blown: MOSFETs, BJTs, resistors, rectifier, and fuse. Then tested the remaining components in the switching circuit. I'm sure there's a good chance the IC is dead, but I'm hoping not.

author: Prehistoricman
author_rank: Regular Contributor
timestamp: February 04, 2020, 12:26:31 am
content: I've attached a simulation of the rectifier with and without the voltage doubler.In 110 mode, the two diodes at the top of the bridge (sorry I couldn't make it diamond-shaped) are bypassed/unused. The remaining two make two half-wave rectifiers that charge each cap separately.

author: Prehistoricman
author_rank: Regular Contributor
timestamp: February 04, 2020, 01:15:34 am
content: I should add that the 110 circuit can then be massaged and simplified in a really satisfying way, and it becomes more obvious how it works.

author: CoffinDodger
author_rank: Regular Contributor
timestamp: February 04, 2020, 04:22:32 am
content: That makes total sense. Forgot about voltage doublers.... So measured the output of the doubler circuit and it's approx. 340VDC... So that's good, took a look at the LD7575PN datasheet to find the next rabbit hole and I think I found my problem. When I fat probed Vcc with OUT it's very likely I fried the current sense pin seeing as the resistors it pulled from were about vaporized.It's a dead chipmuch like this horse. One more dead silicon soldier. Thanks for the lesson!
How the heck do you solder SMD's that have pads underneath? - Page 1
Forum section: electronics / projects

author: ApexM0Eng
author_rank: Contributor
timestamp: July 13, 2015, 10:36:59 pm
content: Such as devices like the one below.http://www.qt-brightek.com/datasheet/QBASS40YGZ.pdfIf you check out Page [5 of 10] you can see a diagram of the device.Pins 6-8 and 9-11 are all mounted underneath.I had a small board made up using the recommended pattern in this document.I have tried using solder paste, by placing very small dabs on the pads then heating,but I am always getting shorts between the inside and outside pins.I really don't like the clearance between the inside pins and outside pins on the recommendedlayout, but i figured it was fine.Whats worse is I can't get in there to fix mistakes as the device is now glued down.Is there a technique i am un-aware of or something? This is quite frustrating.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 13, 2015, 10:51:57 pm
content: Ideally, a paste stencil.It can be hard, but not impossible to get sufficiently little paste with other methods.A pin or toothpick can work sometimes.And of course a PCB with solder resist.

author: nctnico
author_rank: Super Contributor
timestamp: July 13, 2015, 10:59:34 pm
content: Looking at the PDF I see holes going through the display substrate. I'd use short wires and solder them from the top of the display and the bottom of the PCB.

author: digsys
author_rank: Unknown
timestamp: July 14, 2015, 02:45:30 am
content: What I do in these circumstances -Elongate the pads with a larger pad close by. Drop a 35-50th hole in this second pad. Apply flux to the pads, place and tag the display.Using thin solder and a thin tip, heat the pad/hole and run solder down the hole. It will flow all over and pick up the display pads.The PCB should be upside-down for gravity assist.

author: ApexM0Eng
author_rank: Contributor
timestamp: July 14, 2015, 03:51:46 pm
content: So small dabs, we are talking like .5 cubic mm, when fitting on the end of a pin.I was thinking about using a fine syringe to place some in the hole on the device then heating the contact pad on the top, but I am concerned thatif it isn't pressed firmly down that the PCB won't conduct the heat properly.
How the hell is E18-D80NK works? - Page 1
Forum section: electronics / projects

author: lol36
author_rank: Newbie
timestamp: November 19, 2016, 11:19:21 am
content: Hello everybody,How does the E18-D80NK works? I mean, I have stumbled uponhttp://www.idogendel.com/whitebyte/archives/4471(see my translation belew), but he also doesn't have a clue how it works.The translation:QuoteFrom the comments section of the post we also know that:This clear component oscillates on the exact same frequency even when it's alone (with the same configuration).The amount of light getting in does not changes anythingThe lower the voltage the duty cycle gets longer.The output pin of the receiver connects directly to the output of the module.So, again, how the hell this thing works?!?!Thanks ahead for anyone who will try to help!P.S.: sorry for my bad English.

author: lol36
author_rank: Newbie
timestamp: November 19, 2016, 11:30:34 am
content: Quote from: blueskull on November 19, 2016, 11:24:36 amIt's seems like you didn't read the whole long post, and haven't look on the pictures.The whole point is that there is no oscillator nor photodiode nor ASIC in there...And BTW, the "receiver module" can be as simple as a dumb Arduino.

author: lol36
author_rank: Newbie
timestamp: November 19, 2016, 11:50:58 am
content: Quote from: blueskull on November 19, 2016, 11:37:31 amFirst of all, I will be happy to know how you conclude that the receiver is a photodiode+ASIC.Second, it doesn't explain why it partially-responded to a 38kHz signal.Third, this element oscillateswithoutresistor or anything else.And last, what makes it to oscillate?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 19, 2016, 01:38:12 pm
content: 1) There seems to be a photodiode inside the unit as well.2) There is a black blob under the photodiode/transistor thingy at the business end?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 20, 2016, 04:57:04 pm
content: Great. This has me so puzzled I bought one.

author: Andy Watson
author_rank: Super Contributor
timestamp: November 20, 2016, 05:31:59 pm
content: Quote from: Alex Eisenhut on November 20, 2016, 04:57:04 pmDitto! For less than the price of a pint of beer, my curiosity must be satisfied

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 20, 2016, 06:30:20 pm
content: I suppose the lens must add directionality to the thing, and the weird bump in the back of the sensor looks like it's inline with what I perceive to be a photodiode inside the sensor.Usually these things are bolted to sheet metal that's part of whatever conveyor belt/machine/industrial thingy, so the end is exposed to ambient light, I suppose.Maybe it just compares what it sees in front (look at the black guck, it seals the inside against light from the front), but the rear end looks like it's transparent to IR.
How the Peltier effect works, at the atomic level. - Page 1
Forum section: electronics / projects

author: elliottveares
author_rank: Contributor
timestamp: December 26, 2017, 03:03:55 am
content: Found this what explains how the Peltier effect works at the atomic level, what some may find interesting:https://van.physics.illinois.edu/qa/listing.php?id=19853Also, anyone had any real snow outdoors recently in the land down under.Summer in December is just not on!Regards: Elliott.

author: SeanB
author_rank: Super Contributor
timestamp: December 26, 2017, 08:16:22 am
content: Only snow is indoors, but I really am not going to drive 5km to that mall and face the crowds to see it, I can just open the freezer instead. If i want real snow it is a 4 hour drive away in the mountains, should still be some around, even if the day is 27C already.

author: Rerouter
author_rank: Super Contributor
timestamp: December 26, 2017, 10:20:51 am
content: Had hail yesterday. It was fuzzy enough where it piled up to look like snow.Still while i failed to fully grasp the concept. Atleast it heloed clarify why the limitations of peltiers exist.

author: station240
author_rank: Unknown
timestamp: December 27, 2017, 05:17:21 pm
content: One christmas I had frost and ice, took ages to dig it out of the freezer to make room for the food.

author: raptor1956
author_rank: Frequent Contributor
timestamp: December 27, 2017, 09:27:06 pm
content: And in the Chicago and upper mid-west area they are seeing temps nearing -35C...Brian
How this BJT topology Circuit works? - Page 1
Forum section: electronics / projects

author: vinayomo
author_rank: Newbie
timestamp: November 04, 2020, 05:36:41 am
content: HiI have attached the schematic of that instrumentation for IR sensor, I don't understand the working of the topology can anyone help with that it will be great.

author: drdm
author_rank: Contributor
timestamp: November 04, 2020, 07:38:41 am
content: PD acts as a current source when light is shined on it, thus it turns on Q3. When Q3 is turned on it pulls the base of Q4 to GND, thus turning Q4 on and pulling RX to a high voltage level.

author: vinayomo
author_rank: Newbie
timestamp: November 04, 2020, 08:20:35 am
content: If I give an IR pulse of 150 micro sec I get this weird response, and if the IR is turned. ON the change is just of 1V as per the intensity of IR is changed from zero to full brightness.
best charger for object ? - Page 1
Forum section: electronics / projects

author: harrysmith
author_rank: Contributor
timestamp: June 17, 2021, 08:05:05 am
content: Hi everyone, Is there anyone who can provide a brief explanation of how it works. this charger?

author: Gyro
author_rank: Super Contributor
timestamp: June 17, 2021, 08:26:08 am
content: You could maybe make the effort to give some information about what it is. It looks like a backup PSU but it has a microcontroller so nobody is going to be able to interpret the detail of the code.EDIT: The OP keeps changing the content of his post.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 17, 2021, 09:57:10 am
content: Somekind of an optional battery powered door latch with and end course detectionThe mcu circuit is able to sniff the 50hz sector frequencyI dont know if its the kind to lock something while the Ac 50 hz is on, and say the ac is off the circuit operate in some kind of emergency mode with the battery ??

author: phil from seattle
author_rank: Super Contributor
timestamp: June 17, 2021, 02:47:00 pm
content: Quote from: Gyro on June 17, 2021, 08:26:08 amno kidding. right now there is no attached diagram.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 17, 2021, 03:15:48 pm
content: What circuit??
How this cirquit work? - Page 1
Forum section: electronics / projects

author: vamax
author_rank: Newbie
timestamp: October 31, 2021, 11:53:33 am
content: Dear community,I have reversed-engineering some electronic device! Part of the circuit I don`t understand is in the attachment! Can some one help me please to understand what is the purpose of this circuit!?It looks like a capacitor charging and discharging circuit! At the MOSFET gates I have logic 0.The 3.3V supply is common for tow atmega MCUs and some additional circuits!

author: mikerj
author_rank: Super Contributor
timestamp: October 31, 2021, 12:07:46 pm
content: Possibly some kind of memory backup. When the MOSFETS are switched on the 0.22F capacitor is charged to half the supply rail (~1.65v). When the 3.3v rail drops low enough current can flow from the capacitor though the BAT54C and Q802A body diode into the 3v3 rail though it's going to be a pretty low voltage with the two diode drops, maybe 1v ish.
How this Discrete Infrared receiver works surprisingly well ! - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: January 11, 2022, 01:23:38 pm
content: Hi,The transmitter is working on a 600Hz square wave, This board easily works down to 5 to 10 Meter range, I have taken some close up photos, so How the receiver is implemented?Note that this is only the receiver board, the transmitter is a single Hex converter with a BC817 Transistor driving the transmitter @ 600Hz.

author: Fraser
author_rank: Super Contributor
timestamp: January 11, 2022, 01:45:03 pm
content: This takes me back to my early days of electronics and building remote controls using IR or RF.I recall many of the simple circuits looked for just a carrier or a carrier containing fixed modulation. It was only when you wanted more than one function across the link that an encoder and decoder became necessary. IIRC the SL490 IR encoder was a popular choice for hobbyists. I think it was also known as the ULN4000. The age old problem with the the very simple carrier only based systems, whether they were IR or RF, was external interference that caused random control events that were not desirable. The use of properly coded transmissions solved that issue but unintentional jamming by external signal sources remains an issue, even to this day.Fraser

author: Terry Bites
author_rank: Super Contributor
timestamp: January 11, 2022, 02:31:39 pm
content: I see at least two ics- whats discrete about that? You've got an integrated solution there.https://www.elprocus.com/difference-between-discrete-circuits-integrated-circuits/

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 11, 2022, 02:34:07 pm
content: Appears to be a bandpass filter combined with a peak detector.
How this power supply work? - Page 1
Forum section: electronics / projects

author: navidrct
author_rank: Regular Contributor
timestamp: May 19, 2016, 09:32:20 am
content: HiThis power supply is 3w and its small.I want to build something like this.Size matter to meWhat topology should I use for small power supply?Sent from my HTC Desire 820ts using Tapatalk

author: Maobuff
author_rank: Contributor
timestamp: May 19, 2016, 09:36:57 am
content: It's looks like a switch mode power supply, do you spot coil on it?

author: navidrct
author_rank: Regular Contributor
timestamp: May 19, 2016, 09:46:30 am
content: Quote from: Maobuff on May 19, 2016, 09:36:57 amno there is not

author: navidrct
author_rank: Regular Contributor
timestamp: May 19, 2016, 10:23:08 am
content: Quote from: AcHmed99 on May 19, 2016, 10:22:15 amThat what I think tooSent from my HTC Desire 820ts using Tapatalk

author: Kjelt
author_rank: Super Contributor
timestamp: May 19, 2016, 10:50:55 am
content: So step 1: reverse engineer the schematic, write it down and post it here.

author: navidrct
author_rank: Regular Contributor
timestamp: May 19, 2016, 11:12:42 am
content: Quote from: Kjelt on May 19, 2016, 10:50:55 amI'm on itSent from my HTC Desire 820ts using Tapatalk

author: ataradov
author_rank: Super Contributor
timestamp: May 19, 2016, 04:52:05 pm
content: Also, watch numerous light bulb power supply reverse engineering videos by bigclive -https://www.youtube.com/user/bigclivedotcom

author: navidrct
author_rank: Regular Contributor
timestamp: May 19, 2016, 04:53:30 pm
content: Quote from: ataradov on May 19, 2016, 04:52:05 pmThanks allotSent from my HTC Desire 820ts using Tapatalk

author: navidrct
author_rank: Regular Contributor
timestamp: May 21, 2016, 06:24:59 am
content: Quote from: ataradov on May 19, 2016, 04:52:05 pmthanks alot
How to achieve minimum load on a negative voltage rail with current source? - Page 1
Forum section: electronics / projects

author: Esquared
author_rank: Contributor
timestamp: November 30, 2020, 04:49:04 am
content: Hello I am doing something similar to what Dave was doing inhttps://youtu.be/6Otr1I0OR18. My problem is I have designed a dual tracking PSU (+21VDC 0VDC -21VDC) I am unsure how I would go about achieving my minimum load on the negative rail, since the LM334 and other constant current sources are only positive input. Is there a way to achieve this? My gut instinct is to use the positive rail to set both currents but it is not clear how I would achieve that. To use the positive voltage as a signal and adjust the load on the negative rail.

author: Marco
author_rank: Super Contributor
timestamp: November 30, 2020, 07:23:50 pm
content: LM334 is not only positive input ... you can treat the LM334 with the resistor as a two terminal device, whether the top gets connected to a positive rail or the bottom to a negative rail is irrelevant. It can't push current from a negative voltage to a positive, but that's not relevant here.If you don't mind not being able to regulate down to 0 volt, you could just add one LM334+Rset between the positive and negative output rails.If your circuit is able to regulate down to 0 volt and you want to keep it that way, put one LM334+Rset between the positive input rail and negative output rail and another between the negative input rail and the positive output rail.PS. you would also need to add a resistor in series to drop a little voltage, so you don't exceed the maximum rating of the LM334 ... it's only max 40V, not 42V.

author: Esquared
author_rank: Contributor
timestamp: November 30, 2020, 11:11:37 pm
content: Thanks! I'll set up the LM334 as you said in the second case. This is able to regulate down to 0V so I'll use that configuration that maintains that. So when you say input rail you mean before the regulators?

author: Marco
author_rank: Super Contributor
timestamp: December 01, 2020, 01:04:27 am
content: Yah, that's what I meant.
how to add an input for an expression pedal - Page 1
Forum section: electronics / projects

author: fbiramba
author_rank: Newbie
timestamp: May 08, 2020, 09:36:12 am
content: Hello I would like to add an input for expression pedal on my effect pedal for guitar.The expression pedal is a potentiometer of 10k (generally) controlledwith the foot.This pedal will control a 50k potentiometer (if the exp pedal is not on, the user can use the normal pot) there will have a switch to choose between exp pedal or normal potI do a schematic with vactrum vtl5c3/2 but it's expensive. If someone know an Ic to replace this ...I post the schematic and tell me if there's mistakebest regardsfranck

author: sam[PS]
author_rank: Contributor
timestamp: May 15, 2020, 11:18:03 am
content: You don't need any IC for that, just a Jack socket with switching contacts (they takes different names from one manufacturer to another) here is an exemple :https://www.neutrik.com/en/product/nmj6hc-sOn one side you got the three terminals from the jack plug and on the other side you got three corresponding terminals that we'll call the switched terminals. How it works is when no jack is plugged both side are connected, but when you plug a jack that mechanically disconnect the switched terminals so they end up floating.So what you do is connecting the three jack terminals to your circuit in place of your internal pot, then you connect the internal pot to the three switched terminals of the jack socket and Bob's your uncle.Just my 2cts...
How to add noise to a sine wave to test filter - Page 1
Forum section: electronics / projects

author: Dmeads
author_rank: Regular Contributor
timestamp: October 06, 2019, 01:36:25 am
content: Hi all trying to test some filters and I am wondering if there is a way to add a little noise to a sine wave? I have basic lab equipment but maybe I can just use a really long wire from function generator to filter? I heard long jumper wires can add some noise.

author: moffy
author_rank: Super Contributor
timestamp: October 06, 2019, 02:49:38 am
content: Use a summing inverting opamp with two resistors as inputs, one for your sine wave and one for the noise. For the noise source you could use a zener with lots of AC amplification, or a digital pseudo random generator with a filter to limit the bandwidth of the noise.

author: OM222O
author_rank: Frequent Contributor
timestamp: October 06, 2019, 01:28:34 pm
content: if you're not drawing significant current and just want to test a filter circuit, use a signal generator with 2 channels: 1 to produce the sine wave, 1 to produce the noise, then connect them in series. if you only have access to a single channel signal generator, try some of the noise generator circuits which use the 74 series logic to make white / red etc. noise, the reduce the amplitude (maybe with a potential divider followed by a buffer amp) and again, connect the outputs in series.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 06, 2019, 01:52:08 pm
content: If you're working within the audio range, use an app like Audacity to make a noisy sine wave.

author: Seekonk
author_rank: Super Contributor
timestamp: October 06, 2019, 02:22:04 pm
content: I picked up a couple pink noise generators used to make masking noise in office PA systems. It only used two common CMOS chips to do it. We had a noise injector made from two big big motor contactors in a relay race boxed in a giant piece of foam. Great test for line noise.

author: moffy
author_rank: Super Contributor
timestamp: October 06, 2019, 11:55:51 pm
content: You don't even need the opamp to add the noise, just two resistors joined together, one for the sine the other for the noise.
how to adjust opamp offset voltage - Page 1
Forum section: electronics / projects

author: hemnath
author_rank: Newbie
timestamp: March 29, 2017, 04:15:49 am
content: Hi,I have applied zero volt to opamp buffer and the output voltage is 1.3mV. I assume that's because of input offset voltage and bias currents.(tested with ADA4522, LTC1151, LTC2057).Is it possible to reduce to 0V?

author: Zero999
author_rank: Super Contributor
timestamp: March 29, 2017, 10:49:09 am
content: What's the input impedance?Are you sure it isn't the offset voltage in your multimeter? Measure both the input and output voltages.

author: wraper
author_rank: Unknown
timestamp: March 29, 2017, 11:00:30 am
content: Do you use bipolar power supply or single supply?

author: danadak
author_rank: Super Contributor
timestamp: March 29, 2017, 11:22:24 am
content: Some techniques -http://www.analog.com/media/en/training-seminars/tutorials/MT-037.pdfRegards, Dana.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 29, 2017, 04:59:47 pm
content: Offset voltages are specified with respect to the input side. How much this will be a the output depends on the circuit.With the zero offset OPs listed, these is usually no offset adjustment. So it depends on the circuit. Often the offset is so small (e.g. < 2 µV) that an adjustment is not needed at all - this is the whole point of calling then zero offset OPs.

author: Zero999
author_rank: Super Contributor
timestamp: March 29, 2017, 05:13:00 pm
content: Quote from: Kleinstein on March 29, 2017, 04:59:47 pmYet the original poster is measuring 1.3mV, so their either doing something wrong or they're not using the op-amp they think they are i.e. it's fake.
HOW TO APPLY DESIGN RULES WHILE ROUTING IN EAGLE? - Page 1
Forum section: electronics / projects

author: rithi3
author_rank: Newbie
timestamp: December 17, 2012, 08:33:55 am
content: While routing itself, how to apply the design rules in Eagle? Now the traces are getting overlapped with vias & pins of different nets. I want it should get cleared from other nets while routing.Plz help me. Thanks!!!!

author: Lightages
author_rank: Unknown
timestamp: December 17, 2012, 05:24:54 pm
content: How about posting the questions in the correct area on the forum instead of spamming the wrong area with many questions?https://www.eevblog.com/forum/eda/How about posting once with all the questions instead of spamming?
How to approach design of TFT LCD graphics and menus? - Page 1
Forum section: electronics / projects

author: Alex
author_rank: Regular Contributor
timestamp: August 10, 2022, 10:05:16 pm
content: Hello, I am looking for some steering on the development of graphics / menus for small displays in embedded devices (eg nest thermostat).We are developing a new product that utilises a 3" colour circular display. We are good electronics and firmware engineers but poor when it comes to usability and user interfaces. The product is using an STM32F7 class MCU for the display, a magnetic stylus user input (similar to a pointer) and a 432x432 pixel, 3" circular display. We are aware of the TouchGFX library. The product will use nested menus for configuration.I am wondering what is the proper workflow/process to go about designing the menu and graphics? Is it a matter of forming a team with a UI/UX person, a graphical designer and an embedded firmware engineer?Alex
How to assemble DIN cable thing - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 15, 2023, 04:44:05 pm
content: Switchcraft 15DL7M. It's pretty simple, it's a DIN connector. But there's this brass sleeve, and I haven't found any assembly instructions.I'm guessing this goes over the cable, the shorter end is to be crimped and the longer end gets shoved into the strain relief?I wanna be sure because I cleverly only ordered one, so I wanna get it right.Why yes it's for a Commodore 64 power supply.

author: ajb
author_rank: Super Contributor
timestamp: May 15, 2023, 05:06:12 pm
content: I would assume the longer end gets crimped to the outside of the cable, and then it's that rim around it that prevents the sleeve from getting pulled out of the strain relief. But that wouldn't prevent the cable from rotating within the strain relief, unless maybe the shell clamps very tight around it. Is the hole where the strain relief sits just a plain round hole, or does it have some sort of shape that might prevent the strain relief from rotating?

author: SL4P
author_rank: Super Contributor
timestamp: May 16, 2023, 01:20:14 am
content: DIN audio plugs… the curse of my life since the mid 1960s !

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 16, 2023, 02:56:30 am
content: That's why I got this expensive one, it feels like a LEMO connector compared to the regular trash DIN connectors!Plus I've wanted a 90 degree power connector since the 1980s.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 16, 2023, 06:01:11 am
content: 42 years later lolllSome of them where a nightmare to solder, that damn screw passing into the wires, if not carefull you snapped some of them
How to assemble this connector?  - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: July 15, 2016, 06:10:35 am
content: Whenever I see a slot like this for a wire in a connector I think insulation displacement. I presume there's a special tool to assemble these to the wire, but is there a reliable method that doesn't require buying the tool? Need to assemble one 3-pin of this type.Thanks.

author: charlespax
author_rank: Regular Contributor
timestamp: July 15, 2016, 09:07:43 am
content: Duplicate thread. Answer posted inhttps://www.eevblog.com/forum/beginners/how-to-assemble-this-connector-71113/
How to add these components on LTspice for simulation - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: July 31, 2021, 02:20:55 pm
content: I would like to add these spice models so i can simulate them in LTspice.PBSS4350X (.txt)PBSS5350X (.txt)AO4407A (.mod)I have looked intoon how to add the models, but when I opened the library which contains all models, it looks different on the text files. The PBSS has a .SUBCKT and a .MODEL Diode on them. Do I have to add them to the diode file too?The .mod file is even much more confusing, the files contains an NMOS where the mosfet where it came from is a PMOS.My question is how do i add these files in proteus so i can simulate them?It may be of note that doing method 1 in the turtorial where the spice text is just place on the drawing area results in an error.
How to autodetect Aviation microphone type - Page 1
Forum section: electronics / projects

author: bklein
author_rank: Contributor
timestamp: April 21, 2022, 09:59:31 pm
content: Aviation microphones have several types. Electrets, amplified electrets, dynamic, amplified dynamic, and more.I came across a hand held transceiver that somehow autodetects the microphone type. This would involve setting necessary Vbias (aviation mics are higher voltage than commercial electret mics) and gain. How do they do this? Is there a special IC out there for it?

author: m3vuv
author_rank: Super Contributor
timestamp: April 22, 2022, 07:16:29 pm
content: had some nato pilot headsets,im sure the mics were 600 ohm dynamic types,sounded low and basey on my ts-50.
how to avoid ground loops in battery powered projects? - Page 1
Forum section: electronics / projects

author: Sv443
author_rank: Newbie
timestamp: January 14, 2018, 02:46:29 pm
content: Hi, I'm making a bluetooth speaker right now but no matter what I do, I keep running into a really annoying problem. I am using a TP5000 3A li-ion protection board. The 4V output gets amplified to 12V to drive the speaker and to 5V to power the KRC-86b bluetooth module. But if I do that I get really annoying distortion and background noise. I have heard that sensible electronics and audio-electronics sometimes run into this problem too and I wanted to know how professional manufacturers solve this and how I can solve this issue.Please keep your answers simple, I'm not the best electrician.Thanks!

author: madires
author_rank: Super Contributor
timestamp: January 14, 2018, 02:55:02 pm
content: Could be the boost converters. Do you got a lab PSU to power the amp and the Bluetooth module directly for testing?

author: Sv443
author_rank: Newbie
timestamp: January 14, 2018, 06:33:00 pm
content: Quote from: madires on January 14, 2018, 02:55:02 pmYes I already tested it with an external PSU and it solved the problems. And I also think its the boost converters but without them I don't know how to do it.

author: David Hess
author_rank: Super Contributor
timestamp: January 15, 2018, 02:14:02 am
content: Single point grounding to prevent ground loops and RLC decoupling between modules is usually enough to prevent problems. In extreme cases with audio circuits, I have used currents instead of voltages or instrumentation/difference amplifiers to remove ground noise.

author: madires
author_rank: Super Contributor
timestamp: January 15, 2018, 11:14:18 am
content: You could try adding LC filters to the outputs of both boost converters, maybe 10 or 22µH and 470µF as a starting point.

author: ovnr
author_rank: Frequent Contributor
timestamp: January 15, 2018, 11:28:33 am
content: Have you checked which power rail is the biggest problem? Consider adding linear post-regulators to the boost converters.If you're adding LC filters like madires suggests, make sure that you're making a properly damped system. A low-ESR inductor paired with a low-ESR capacitor will ring at certain frequencies. Using a higher ESR inductor - or even adding some series resistance - plus a good old aluminium electrolytic will make it easier to avoid any such issues.
How to better connect decoupling caps with BGA on top side? - Page 1
Forum section: electronics / projects

author: gandi
author_rank: Newbie
timestamp: March 23, 2021, 01:33:31 pm
content: Hi,I am currently designing a board for a display that includes SDRAM, NOR flash, ethernet, USB,...The board should "stick" on the back of the LCD panel, therefore I have to put all componentson the top layer.I have positioned the caps on the outside of the BGA package and now I need some helpto determine which wiring strategy is better or which one is a no go.Stackup: #1 High Speed, #2 GND Plane, #3 & #4 Low Speed, #5 Supply Plane, #6 High Speed1. Using solid supply plane2. Supply plane with keepout area and track for every supply pinIs the first one bad for decoupling behaviour?Does the second one need a GND plane in between to keep the impendanceof the tracks on layer #6?BR Martin

author: richard.cs
author_rank: Super Contributor
timestamp: March 23, 2021, 02:56:49 pm
content: I would definitely go for the first one. That's about as good as you'll get with components on one side (BGA pinouts are generally chosen on the assumption that you'll put the decoupling capacitors on the back).

author: gandi
author_rank: Newbie
timestamp: March 24, 2021, 07:10:43 am
content: Hi,tank you for the quick response. I will use the first pattern.
How to bring down the LT3080 to 0V output - Page 1
Forum section: electronics / projects

author: konfu
author_rank: Contributor
timestamp: March 11, 2013, 10:21:11 pm
content: Hi folks,I am trying to build my own bench top power supply (like quite a few people on the forum) and I ran into an issue about the LT3080's output voltage:It doesn't go down to what the theoretical minimum should be: 0V !!Why: Well - there is this 1mA current source occupying some millivolts. Bloody hell!After playing around with some ideas I found out (God bless Google and YouTube) that a negative feed to the LM334 might help. And well - it does ;-)See attached schematic for your reference.I used a CAT660 (newer version of the MAX660 or LM660) to generate a 3.3V negative voltage feeding into the former GND input of the LM334. Works like a charme!CheersFlorian

author: ivan747
author_rank: Super Contributor
timestamp: March 12, 2013, 02:52:18 am
content: If you are careful enough you can make an LM317 go to 0V too. You use this chip and you create a -1.25V reference. Now you put any voltage in the ADJ pin of the LM317. If you bring it down to -1.25V the output will be 0V, so theres a 1.25V offset of course. You have to use a current source like you are doing right now as well, I am guessing. If you are going to use a DAC to connect to the ADJ pin, you have to use the -1.25V as the negative reference. In fact you may have to make the -1.25V rail your digital "ground" (I think it's more of a common terminal) and make the positive supply 3.75V if you are using 5V logic.
how to build a capacitance multiplier with variable bias current - Page 1
Forum section: electronics / projects

author: qwaarjet
author_rank: Regular Contributor
timestamp: September 12, 2019, 04:55:31 am
content: I have an application where I want to clean up the noise from a switching converter and putting large amount of capacitors on board isn't really a viable option size and power dissipation limited. A capacitance multiplier seem like a good space and cost effective way to do this. However the current draw has the potential to swing over a wide range. To throw some real number this say 10ma to 1000ma @~24V. Now in the situation where I'm drawing less than ~50mA I want really good noise rejection but as the current increases I care less about the noise rejection and become more concerned with the heat build up in the transistor. So I would like to reduce the effective R value in the multiplier raising the bias current as output current increases. However the only ways I can currently think to do this is with a rather convoluted series of opamps and I would think there is a more elegant way to do this. Anyone know of a topology that would allow a function like this?

author: Whales
author_rank: Super Contributor
timestamp: September 12, 2019, 06:01:10 am
content: Shunt resistor to measure current draw -> optocoupler -> bias ?You may want to pre-bias the optocoupler somehow so you don't need as much Vdrop across the Isense resistor.
How to build E-field sensor? - Page 1
Forum section: electronics / projects

author: dext0rb
author_rank: Contributor
timestamp: January 08, 2020, 03:59:47 pm
content: Hi!I would like to experiment with generating extremely low-frequency E-Fields (1-10 Hz) by using some interdigitated electrodes. (IDE)You know, those flat electrodes with the fingers and the spacings and whatnot.I am looking to make fields in the range of 1 to 10 V/cm that extend .4 to 1 cm above/below the electrode.How can I build/set up some equipment to create and test/verify these fields. I am not really familiar with doing this kind of electronics work.Thanks for reading and any help.

author: SG-1
author_rank: Regular Contributor
timestamp: January 09, 2020, 05:37:08 am
content: Check out this link to Sci.Hobbist charge detector.http://amasci.com/emotor/chargdet.html
How to calculate a CD4007 crystal oscillator? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: November 14, 2015, 02:16:42 pm
content: Still about my DIY DMM project, still a all-through-hole construct, still 4000-series CMOS galore.The ICL7135 calls for a 120kHz clock. Instead of fighting the instabilities of resistors and capacitors I am going the crystal way, by clocking it at 128kHz with a crystal oscillator based on a 128kHz crystal and CD4007, in the true heart of a all through-hole construction. Now how do I do this?Or, how do I quadruple a 32768Hz watch crystal into 131072Hz using CD4046?

author: Alex Nikitin
author_rank: Super Contributor
timestamp: November 14, 2015, 02:35:56 pm
content: Quote from: technix on November 14, 2015, 02:16:42 pmIf you read the datasheet for ICL7135 carefully, you would realise that the clock frequency choice is important. 120kHz would work OK for 60Hz mains supply rejection, but not for 50Hz. The most convenient is 100kHz which would help to reject both 50Hz and 60Hz mains frequency. In the datasheet for ICL7135 from Maxim there is a circuit for 100kHz crystal clock using 4000 series chips.CheersAlex

author: SeanB
author_rank: Super Contributor
timestamp: November 14, 2015, 02:38:20 pm
content: 4007 data sheet included in the application notes how to drive a crystal with it. Involves limiting current in the inverter stage using some 1M resistors in the power and ground to the 2 transistors, and using the remaining 2 inverter stages as buffers. 128kHz instead of 120kHz though is going to lose all the mains rejection of the converter, you might want to look for a crystal you can divide down using a ripple divider to 120kHz instead.

author: technix
author_rank: Super Contributor
timestamp: November 14, 2015, 03:14:51 pm
content: Quote from: Alex Nikitin on November 14, 2015, 02:35:56 pmFound 6.4MHz crystals in HC49/S and cost 10 cents each. Divide that down to 100kHz using CD4060 and it would be good to go.
How to Calculate E-Field Magnitude From an E-Field Probe - Page 1
Forum section: electronics / projects

author: standardengr
author_rank: Newbie
timestamp: May 25, 2018, 09:44:27 pm
content: Hi everyone!Can anyone explain how to use an E-field probe to actually measure magnitude of an E-field? I know a lot of people use E-field probes to pinpoint RF interference but how does the signal received on the probe actually relate to the E-field magnitude? I tried looking at how electric field meters work in hope it would explain it but I'm having a hard time finding material on the subject.Thanks!

author: skipjackrc4
author_rank: Regular Contributor
timestamp: May 25, 2018, 11:19:48 pm
content: The probe should have an "antenna factor" supplied by the manufacturer that will give you the conversion between measured voltage and field strength over frequency. Typically the AF will be supplied in dB and will be added to the measured voltage in dBuV to get dBuV/m. It's important to note, however, that the presence of the near-field probe influences the field, and the corrected field strength is going to be somewhat approximate. Even EMI measurements have this problem at low frequencies--the field "measured" by the antenna is not necessarily the actual field strength.The probe may also be sensitive to polarization, depending on the design.
How to calculate the components for this driverless LED light (230VAC)? - Page 1
Forum section: electronics / projects

author: Greybeard
author_rank: Frequent Contributor
timestamp: January 21, 2024, 07:49:23 pm
content: Related article:https://www.ledsmagazine.com/leds-ssl-design/modular-light-engines/article/16695199/driverless-led-light-engines-deliver-up-to-93-efficiency-and-no-perceptible-flicker-magazine
How to calibrate? - Page 1
Forum section: electronics / projects

author: daisizhou
author_rank: Super Contributor
timestamp: September 10, 2024, 07:00:07 am
content: Hi GuysPlease forgive me for posting for help again,I have been trying to enter calibration mode for the past few days, but I have failed so far.VT650 is still in a faulty state, the pressure value changes irregularly and cannot maintain zero position.It looks like I need to enter calibration mode and recalibrate to be successful,I read the FLUKE user manual, but it does not describe how to enter calibration mode. It only mentions sending the unit back to FLUKE for calibration.This console has lost its warranty. It belongs to me personally and I do not plan to send it back to Fluke for repair because the repair cost is too expensive.I hope that through my own efforts and the help of my friends, I can return to normal.In order to describe the fault more accurately, I took a video and picturesIn the manufacturer's firmware upgrade description, I vaguely saw a little clue, but I don't know if it is useful. Maybe it can only be analyzed by reverse engineering the firmware. But I am a beginner. If you can reverse the firmware, I hope you can help me. Thank you.
How to capture serial data with a Rigol Scope - Page 1
Forum section: electronics / projects

author: maketronix
author_rank: Newbie
timestamp: December 19, 2012, 06:33:19 am
content: Has anybody taken the time to write up instructions / do a video on how to capture a serial bitstream (I'm thinking I2C as I write this) with a Rigol scope, so you can visualize the bits being passed / debug the protocol? Just asking, because I tried and failed to successfully do this last week, and ended up buying a logic analyzer.It seems like a lot of us have this scope, it would be nice to have such a training aid

author: marmad
author_rank: Super Contributor
timestamp: December 19, 2012, 07:29:53 pm
content: You might get more responses if you mention what model/series of Rigol scopes you're asking about. I'm assuming the E series, but I don't know for sure (although obviously you don't mean the new Rigols, since all of the UltraVision scopes come with I2C triggering and protocol decoders built-in by default).

author: maketronix
author_rank: Newbie
timestamp: December 20, 2012, 03:56:08 am
content: Well personally I'm using an e series (DS1052e) but I'd certainly be interested in other models if 'similar techniques apply'.

author: Harvs
author_rank: Super Contributor
timestamp: December 21, 2012, 11:28:50 am
content: I'd say the reason behind the question about the E vs D is because the D has the logic level channels.Obviously the DS1000 series doesn't have serial decode built in - which is a shame. However, most of the time all I need to look at is whether the SPI clock polarity, _enable is timed correctly etc for the specific device I'm trying to talk to. To do this, just a decent capture of the signal is more than enough.So there's two parts to that, one is triggering on the right bit of the signal you're after, and the other is about capturing enough data. Dave has explained DSO triggering in a number of videos and really I don't have anything to add. Obviously a signal shot capture is what you're generally looking for to manually analyse the signal.As to capturing the data, first thing is to turn on long memory depth (if needed). Then bring up the horizontal menu and note it has the current sample rate. Assuming you know what you're bit rate is, then you can change the time base until you get the sample rate to a level that will capture the number of bits you're after (remember the 1MEG sample depth, which will be split between two channels.) I keep to about 100 samples per bit as a minimum, and that should give you a 5000 bit capture at rates that can use the full memory depth. Obviously far more than you're going to be scrolling through on a 5" display.Then once you've completed the capture, wind in the time base to zoom in and use the horizontal offset to scroll through the waveform.
How to chamfer semi-rigid coax center conductor? - Page 1
Forum section: electronics / projects

author: nexus
author_rank: Regular Contributor
timestamp: November 07, 2022, 03:02:36 am
content: Hi all,I am restoring an Agilent E8357A that was left for dead. The power supply and CPU are fixed; all that remains are to replace the receiver access loops that were smashed beyond repair.These are made from 0.141 semi rigid cable bent into a "U" shape with two soldered on SMA male connectors.I have the tools to bend and cut coax; but I also noticed that there is a nice chamfer on the center conductor. Any idea on what kind of tool would be used to accomplish this?The cable I am planning to use is Pasternack PECX008, which is 0.141" diameter with a 0.04" (1.02mm) center conductor.

author: hubi
author_rank: Regular Contributor
timestamp: November 07, 2022, 03:13:39 am
content: Not sure how this is done professionally. You could try a cup burr on a Dremel if you have one and see what happens?

author: nexus
author_rank: Regular Contributor
timestamp: November 07, 2022, 04:51:10 am
content: Quote from: hubi on November 07, 2022, 03:13:39 amThat sounds like it could work. I do have a dremel handy.I also saw this thing, not sure if it is "the tool".https://ripley-tools.com/product/dbt-u/Anyone used one before?

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: November 07, 2022, 05:07:05 pm
content: I have an oldAmp 59981-1 SMA tool kit, which comes with the 311396-1 Cable Dressing Fixture. This is a block of tool steel with a sloped face, the idea is you stick in the stripped center conductor so that the sloped face exposes a small amount of the center conductor. While rotating the wire slowly with your fingers, use a file to form the chamfered edges. The instruction sheet has illustrations of the process, see Figure 5 detail B.I suppose one could machine a similar fixture with the right dimensions. In a pinch, you could free-hand it with a fine file, the idea is to smooth out the burrs, the chamfer is not strictly necessary.The Ripley deburr tool is designed for cables with a larger OD (starting at LMR-240), so won't be useful for a 0.141" OD semi-rigid. I've used a similar tool on 0.5" heliax.