hybridfree/eevblog-posts huggingface dataset:
Relays [220V] - Page 1
Forum section: electronics / beginners

author: Rihards Veips
author_rank: Contributor
timestamp: April 03, 2014, 12:47:19 pm
content: I am working on a project at my school for a lighting show in mycity in November.I will probably be using an Arduino and build something similar to a LEDcube but it will be a transistor cube that will be turning on relays. Therelays will turn on 220V 7W LED lamps, but I don't know what kind of relays Ineed. Can anyone help me please?

author: electronics man
author_rank: Frequent Contributor
timestamp: April 03, 2014, 03:18:59 pm
content: AC or DC

author: Rihards Veips
author_rank: Contributor
timestamp: April 03, 2014, 03:22:23 pm
content: ACThis is the electronics store I buy things from (Relays):https://www.elfa.se/elfa3~en_en/elfa/init.do?toc=18721&name=RelaysNot sure if the link will work...

author: madires
author_rank: Super Contributor
timestamp: April 03, 2014, 03:35:01 pm
content: Ok, so you want to switch 220V AC. Will each relay switch a single 7W light or multiple in parallel? That way we determine which load the relay has to support. The relay type will be a SPST (Single Pole Single Throw). The next point is the driving voltage, typically 5V, 6V, 12V or 24V. Please choose one based on your power supply.

author: Rihards Veips
author_rank: Contributor
timestamp: April 03, 2014, 03:40:47 pm
content: Each relay will switch on 1 light.Driving voltage: 5V

author: electronics man
author_rank: Frequent Contributor
timestamp: April 03, 2014, 04:06:18 pm
content: It's very easy to find a relay with your specs

author: Rihards Veips
author_rank: Contributor
timestamp: April 03, 2014, 04:09:59 pm
content: Yes, but I don't know if the relays I found are not too powerful(higher price) and I don't really know what kind of relays I need - Solid state or signal ect..

author: madires
author_rank: Super Contributor
timestamp: April 03, 2014, 08:44:20 pm
content: Please look for power relays. Since you switch just 7W any relay supporting >=1A should be fine, likehttps://www.elfa.se/elfa3~en_en/elfa/init.do?item=10-573-78&toc=18836.

author: Rihards Veips
author_rank: Contributor
timestamp: April 04, 2014, 01:28:31 pm
content: ok thank you
Relays..JQX - standardized numbering system? - Page 1
Forum section: electronics / beginners

author: K5_489
author_rank: Regular Contributor
timestamp: February 17, 2022, 02:22:26 pm
content: I recently came upon a need for a couple high power DPDT type relays with 12VDC coils, and can handle a minimum of 100amps across the main contacts. I was planning a roll-my-own battery series/parallel switch for an on board welder system for an off road truck where the welder would be powered via 24VDC, and still being able to use the batteries as aux batteries on the 12VDC system, as I won't be using the welder very often.I have since decided the risk of accidentally applying 24VDC to a 12VDC circuit due to either vibration induced relay bounce, relay failure, or just plain human error factor was too great, and have since decided to accomplish the changeover via just manually switching connectors as needed. However, I'm still curious about how relays are numbered...Up until now, I've never really had a need for anything other than the common 30 amp automotive relay sold in the auto parts stores, often called a Bosch relay or lighting relay, or was something that I was replacing a defective part that I could just go and search out part number blah blah blah for, so I never really got into the details of how these parts are numbered.In doing some Googling to find out what's available, I noticed a LOT of relays carry a JQX-xxx type part number on them, despite a seemingly wide variation of relay type. Such as one sitting in my Amazon cart now that's a JQX-62F-2Z, or others that I'm seeing such as JQX-13FL, JQX-12F-2Z, JQX-10F-3Z, etc. I'm assuming that this is some kind of standardized part number system for relays, where each section is denoting a specific type of something?I've tried Googling for a while to find some kind of breakdown for how to ID or specify relays based on this, and am coming up with nada. Such as I know I needed a DPDT type relay, 12VDC trigger coil, 24VDC 100amp switching capabilty, and screw type terminals that I would use ring terminals with.Or am I just completely misunderstanding the JQX-XXX part of it...or worse, being completely confusing in this post altogether?
Relays -- outdated book? - Page 1
Forum section: electronics / beginners

author: MrAureliusR
author_rank: Unknown
timestamp: August 06, 2013, 08:22:43 pm
content: I just got this book from my library -- it's a few years old (1988 -- same year I was born) and there seems to be a lot of good info in it. I just got to the part about rotary switches and relays -- I attached a scan of the first page about relays. I'll also scan a few other pages, I'm just checking to see if you guys think it's decent info or if anything seems off or too dated.EDIT: Resized the images, always forget to do that

author: MrAureliusR
author_rank: Unknown
timestamp: August 06, 2013, 08:26:32 pm
content: Filters --

author: Neilm
author_rank: Super Contributor
timestamp: August 06, 2013, 08:27:07 pm
content: Relays haven't changed much over the years. Details might have been changed but the underlying technology is still the same - current flowing through a coil attracts a movable bit of metal that opens (or closes) a contact.

author: Bored@Work
author_rank: Super Contributor
timestamp: August 06, 2013, 08:46:14 pm
content: The basics of filters also haven't changed much. Since I am a fan of first getting the basics right that book should still be ok.However, above the basics things have changed. The times that you looked through a 600 page filter catalog to find a suitable filter for a particular application are largely gone. There might be some niche areas where this is still done, but for garden-variety filters one punches a few numbers into a filter design software and get it simulated. What numbers to punch in? Well, that's when knowing your basics comes into play.Then there is the now much more popular field of digital filters, something already theoretically known in the 80th, but not very widely used then.

author: MrAureliusR
author_rank: Unknown
timestamp: August 06, 2013, 08:48:17 pm
content: I'm actually flipping through it in more detail now, and I'm quite amazed at the detail and complexity, considering the time and the target audience. By the 6th chapter, they're helping you read TV and Radio schematics (quite complex ones, that had basic digital logic) and near the end of the book it goes into much more detail about digital logic. The first half is dedicated to explaining components and their functions in details.I'm very impressed with this book and would highly recommend it to beginners!How To Read Electronic Circuit Diagrams, 2nd Ed.Robert Brown, Paul Lawrence, James Whitson(c) 1988TAB Books, IncThe first edition was in 1970 (so I guess they needed a 2nd edition by 1988!! I'm guessing they basically rewrote it considering the differences in those 18 years).

author: G7PSK
author_rank: Super Contributor
timestamp: August 07, 2013, 07:42:55 am
content: Virtually no old book is invalid ( I wont go into religious texts) any information is good and very often you find information in old books that for whatever reasons are dropped from modern texts and that help with problems especially in older equipment.But then I am biased as I collect old technical books.
Reliable sellers of pure nickel strips in 0.2-0.3 mm in Europe ? (H-type) - Page 1
Forum section: electronics / beginners

author: JL34
author_rank: Contributor
timestamp: October 17, 2023, 09:22:23 pm
content: Hello,I plan to replace some aging cells on batteries of my work power tools (perforators, grinders, screwdrivers, etc). Mainly of Hilti or Bosch power tools. I think I'll buy some Murata US18650VTC5D cells from Akkuteile, a Kweld, and a SkyRC MC3000 to test and sort the new cells.After some searches, it seems that this sort of battery must be able to delivers near 20A to power this tools. So I should go to pure nickel strips of at least 0.2mm thick.I have difficulties to find this sort of nickel strip in 0.2 thick and precuts format for parallels assemblies (likeH-shape, triangle-shape, 2P, etc). I prefer to go to pre-cuts to avoid welding strips on other strips.Does someone know and can recommend me some reliable sellers in Europe or international that sell that sort of nickel strip ?Thanks in advance

author: alligatorblues
author_rank: Regular Contributor
timestamp: October 18, 2023, 04:55:42 pm
content: Here:https://www.amazon.com/product-reviews/B07P3ZCJXT/ref=acr_dp_hist_1?ie=UTF8&filterByStar=one_star&reviewerType=all_reviews#reviews-filter-bar

author: TimFox
author_rank: Super Contributor
timestamp: October 18, 2023, 05:37:09 pm
content: Here's a quality US supplier of nickel strips, but their stock lengths are quite long.They do ship internationally.https://www.msesupplies.com/collections/lithium-ion-battery-materials/nickel-strip

author: JL34
author_rank: Contributor
timestamp: October 19, 2023, 06:13:14 pm
content: Thanks for your replies.Those sellers do not sell H-type nickel strip, for 4P connection.I will try some aliex sellers. May be with some luck I could have pure nickel..

author: Aurgelme
author_rank: Contributor
timestamp: October 20, 2023, 07:15:30 pm
content: I have shopped from this store, and have received nickels of good quality.https://annbattery.aliexpress.com/store/536657?spm=a2g0o.store_pc_groupList.pcShopHead_186810291.0

author: JL34
author_rank: Contributor
timestamp: October 21, 2023, 12:13:37 pm
content: Thanks @Aurgelme. This shop seems to have all the nickel I need. Perfect !
Capacitive touch over long wires? - Page 1
Forum section: electronics / beginners

author: dteck
author_rank: Contributor
timestamp: January 03, 2015, 11:28:25 pm
content: Hi everyone,Right now I'm trying to play with an Atmel QT2120 capacitive touch controller in standalone mode.What I'm curious about is how to manage "remote" electrodes. I want to have my electrodes fairly far away from the board. Maybe up to 12 Inches (30cm). Now the Atmel datasheet says to reduce stray capacitance around the pins. But with a long wire run I'm worried about them giving false detections. So I thought maybe something shielded like coax might be an option for running out to the electrode. But I imagine there will be some capacitance per distance in the coax itself between the conductor and the shield. but I don't know if it will be enough to be a problem.I'm hoping someone with experience in touch sensing could share some insight on distancing the electrodes from the controllers. And maybe tell me if I'm worrying about nothing.
Remote control buttons design type. - Page 1
Forum section: electronics / beginners

author: dhead
author_rank: Newbie
timestamp: July 16, 2013, 02:16:10 pm
content: Attached is a picture of a rf remote control I've got.As can be seen the only thing that holds the buttons is the glossy sticker.I would like to know how this design of push buttons is called and where I can get these.I found myself very interested in the design of this rf remote control (combo of remote (dual ir & rf), keyboard and gyroscope) based on Nordic Semiconductor nRF24LE1.

author: Paul Price
author_rank: Super Contributor
timestamp: July 16, 2013, 02:48:17 pm
content: This kinda crappy cheapest-possible-way-to-make-a-button switch is custom made by dome-deforming punched metal strips, try using membrane switches or mechanical single station switches instead, much more easier on the fingers, have a nice feel and are more reliable.

author: dhead
author_rank: Newbie
timestamp: July 16, 2013, 05:01:36 pm
content: Thanks Paul.

author: Paul Price
author_rank: Super Contributor
timestamp: July 16, 2013, 05:26:48 pm
content: I easily salvage all the push button controls I could possibly need from discarded home entertainment equipment such as VCR and DVD players or 56k modems or even a CRT tube TV or a now tiny in size LCD monitor.

author: ben_r_
author_rank: Frequent Contributor
timestamp: July 16, 2013, 05:32:12 pm
content: Been looking into keypads myself lately. Google membrane keypads and youll find quite a few companies that make many different styles including this one.

author: amyk
author_rank: Super Contributor
timestamp: July 16, 2013, 06:33:26 pm
content: Those are called "tactile domes". They're probably the lowest-profile tactile switch design available.http://www.clikdomes.com/http://www.snaptron.com/I prefer them to membrane pads, as they're a lot clickier in feel.

author: M. András
author_rank: Super Contributor
timestamp: July 16, 2013, 07:24:31 pm
content: wouldnt be a better idea to use capacitive buttons? no wear on them thats for sure

author: SeanB
author_rank: Super Contributor
timestamp: July 16, 2013, 07:51:56 pm
content: Tact buttons are under a cent each in bulk, and need no extra complex analogue sense and decode electronics to work.

author: ptricks
author_rank: Frequent Contributor
timestamp: July 16, 2013, 09:28:21 pm
content: Consider the application when choosing buttons.Touch sensors suck on tv remotes where membrane works better because you can feel the button press without looking.Whenever possible I like to use switches like the cherry ML brand, they have some that fit well for remotes.
remote controlled volume with avr - Page 1
Forum section: electronics / beginners

author: victor
author_rank: Regular Contributor
timestamp: November 09, 2013, 10:22:07 pm
content: I have an old amp that has no remote control, connected to a directv box. I basically want to control the volume without getting out the couch.I'm open to any other suggestion or approach, but this is my idea. I already played with arduino IR library and it was pretty easy to use a IR module. So I could use an atmel 328 or similar to decode the button press from a remote control, and control the volume.I want to control the input level before it goes to the amp input, so I don't have to modify the internal amp potentiometer, something like this.I could use a servo or digital pot.But to be able to control it using a uC I think digital potentiometer is the way to go, but I have no experience with then, and how many circuitry is required for it to work.Anyone can help me to build this circuitry. I want build something cheap that does the job, I know how to etch pcb and sodder smd, but through hole is preferable.Any thoughts would be more than welcome.

author: Alana
author_rank: Frequent Contributor
timestamp: November 09, 2013, 10:43:20 pm
content: Digital potentiometr in google and look at datasheets.For examplehttps://www.sparkfun.com/products/10613And for volume control you would want logaritmic characteristic of a pot.

author: tszaboo
author_rank: Super Contributor
timestamp: November 10, 2013, 09:09:49 am
content: Ti has a series which is designed for audio use, mainly for preamps:http://www.ti.com/product/pga2310It is easy to use, not cheap though.

author: garak
author_rank: Contributor
timestamp: November 10, 2013, 11:48:28 am
content: Quote from: Alana on November 09, 2013, 10:43:20 pmAlana's suggestion isn't bad. These devices are reasonably easy to drive (they use an SPI interface) and aren't too expensive. You'll need two for doing stereo volume control, but these DON'T feature zero-crossing detection and you may get a zipper-like sound when changing volume. It might also make sense to get a dual-channel model as the potentiometers in these will be more closely matched than two single ones.Have a read of the comments section on the SparkFun page, there are a number of people there who are doing the same thing and got it figured out. You'll find all the SPI commands you need in the datasheet, specifically on pages 47 and up.

author: Psi
author_rank: Super Contributor
timestamp: November 10, 2013, 12:30:19 pm
content: You could also use a motorized pot, like they have in some stereos/amps.Generic H bridge driver on the mcu could control the motor speed/direction easy.
Remote delayed 12 channel switch - Page 1
Forum section: electronics / beginners

author: artyvesna
author_rank: Newbie
timestamp: March 24, 2018, 01:48:23 pm
content: Hi.Given:- a control box containing:--- an Arduino based controller with N-Mosfet switch--- a "switching" PSU 3amp/3.0V regulated- 1.5 meter 2x 22AWG wire unshielded- process chamber containing a fixture/jig with 12 nests equiped with spring loaded contacts for power supply aka. ICT fixture- 12 items:--- normally powered by 2x 1.5V batteries (equipped with electronic "pump")--- max current draw of each is ~250 mA in short (ms) spikes, constant mean is around 70 mAProblem description:Operator loads products in their nests on the fixture and into the process chamber, presses a start button.MCU then starts a sequence and at some point activates a MOSFET(irlz44n) which commutes ground to 1.5 meter wire,which in turn is connected to the fixture where at the moment all the nests are connected in parallel.As you can probably see, all units get powered simultaneously and that is a problem.Beside of voltage drop at ~2V on the common wire, these items initiate a radio comm -simultaneously, on the same channel. This is undesirable.Now, while i admit that the whole design is quite amateur, but this is another discussion.Possible solution:Implement some very compact simple control unit(?) in tandem with some transistor array (like TC7320FG-G M931), to realisesequential/delayed power switching to each of the nests. The whole assembly must fit into a tiny (~ 30 x 50...70 x 10 mm)confined space, meaning almost no heat dissipation.I would appreciate your suggestions.

author: SL4P
author_rank: Super Contributor
timestamp: March 25, 2018, 06:53:39 am
content: First suggestion, maybe to pitch this in the Arduino forum.http://forum.arduino.cc/They are more targeted at programming solutions for Arduino.Second suggestion would be to express the problem in technical English, rather than nests, pumps and ...if you can have a clearly awn black dagram to communicate your ideas - a wiring/circuit schematic can come later.Define the problem first, before you start throwing specific parts at it.What you have may be suitable, but find the goal fi st, before visiting Radio Shack.(I’ll be over at arduino.cc to help when you get there.)
Remote duck decoy - Page 1
Forum section: electronics / beginners

author: Adam60
author_rank: Regular Contributor
timestamp: September 22, 2017, 10:19:09 pm
content: Does anyone havea circuit for a small 6v motor that would allow you to run it remotely? I have a duck decoy that I would like to run like a remote control boat but on a simple scale. Any thoughts? Just looking for different ideas other than the obvious.

author: tautech
author_rank: Super Contributor
timestamp: September 23, 2017, 09:33:48 am
content: Check these guys wares:http://www.rfremotech.com/Others.htmleBay store:http://stores.ebay.com/RFRemotech?_trksid=p2047675.l2563

author: Spaghetti_142
author_rank: Newbie
timestamp: September 24, 2017, 02:15:55 am
content: simple sevro, transmitter, and reciever.

author: Raj
author_rank: Frequent Contributor
timestamp: September 25, 2017, 05:59:54 pm
content: http://danyk.cz/avr_dop_en.htmluuse a mosfet along with it
Remote engine arrestors - how do they work - Page 1
Forum section: electronics / beginners

author: ImABeginner
author_rank: Contributor
timestamp: January 31, 2021, 07:11:26 am
content: I've been seeing some videos of these magic gadgets that claim to use all this wacky voodoo RF magic to arrest engines of cars. I'm curious how these work, as it seems very difficult to get RF under the hood of a car, or even through the radiator.https://youtu.be/7YdukDailvMIf i were to take a guess, I'd say it's a targeted EMP system? I dunno. Anyone have better clue than me how these work?

author: geggi1
author_rank: Frequent Contributor
timestamp: January 31, 2021, 07:43:22 am
content: Probably some kind of pulsed RF device that messes with the electronics in the motor.It does probably not work on very old motors without the electronics.

author: Psi
author_rank: Super Contributor
timestamp: January 31, 2021, 08:36:02 am
content: There has been a EEVblog thread on a similar device years ago and I think it even had a schematic diagram.It was much smaller unit than what their system looks to be though. I'm not sure why. I think the system was about the size of a shoe box and intended to attach to the roof of cop cars.From memory that system was a 2.4ghz pulsed microwave emitter with directional antenna that induced all sorts of noise on the sensors wires going to the ECU in target vehicles. It causing the ECU to get all confused about engine rotation and basically mess up the feedback loop between the CAS, ECU and Injectors.

author: richard.cs
author_rank: Super Contributor
timestamp: January 31, 2021, 12:41:14 pm
content: Quote from: geggi1 on January 31, 2021, 07:43:22 amPetrol cars earlier than about 1980 and diesel cars with a mechanical injection pump (until the early 90s?) are probably completely immune. Quite likely specific models of modern cars just happen to be immune due to lucky cable and component placement, good EMC design, etc.The whole concept seems ethically and legally dubious. It's not like it's guaranteed to only stop the engine and nothing else. All manner of exciting and possibly fatal (for driver, passengers or bystanders) outcomes are possible depending on which systems in the car are affected.Edit: My car has two germanium transistors in the tachometer, and the equivalent of a 1N4001 in the fuel pump, that's it's total semiconductor complement.https://mgb1967.com/wp-content/uploads/2020/06/1967-MGB-wiring-diagram.jpg

author: Psi
author_rank: Super Contributor
timestamp: February 02, 2021, 08:16:20 am
content: I do wonder if it's safe if the driver has a pacemaker.Probably not.
Remote Machine Stop Interfacing - Page 1
Forum section: electronics / beginners

author: Redline99
author_rank: Newbie
timestamp: July 06, 2016, 07:47:16 pm
content: Hi, I have project and yeah I'm total beginner here so having someone look over or make suggestion would be very appreciated.The project is that I have to pull to ground a remote machine stop. The device I have under my control from a computer is a USB solid state pnp FET "switch". (ACCESS IDIO-4). Attached is a simplified wiring diagram with how I think best to get this going, remember I'm a beginner here so I am probably completely wrong. The parts encompassed in a dotted boxes are outside my control. My main dilemma is that I need to pull to ground the remote stop using a P-Channel device. I think I can only do that by adding a N-Channel to the circuit? Is there a way to do this without a N-Channel to accompany the USB IO device?Thank you for any help and suggestions!

author: danadak
author_rank: Super Contributor
timestamp: July 06, 2016, 09:39:02 pm
content: Your solution seems logical. Just insure when P channel is onthe Vgs of the Nchannel turns it on adequately. Also the N channelturn off speed is constrained by the Pchan pull down, but if thisis a "light switch" type of application, ie. the speed you need to turnoff, you are probably ok. Note also as MOSFET turns off slowly itwill experience increased Pdiss due to time it spends in active region.So think in terms of 100's of ohms for P chan pulldown. You can alwaysspice the tunr off to see what effects your Pchan pulldown has.Also consider noise effects from turning off large L loads in the vicinityof the circuit. Choose a FET with appropriate breakdown V, maybediode protect gate of Nchan with zeners if you find a lot of noise inthe circuit environment.Regards, Dana.

author: Redline99
author_rank: Newbie
timestamp: July 07, 2016, 02:41:18 am
content: Thank you Dana that is very good information for me.And just to be sure, am I correct that there is not a simpler method of interfacing without using the N-Channel component?
Remote power outlet switch + normal wall switch - Page 1
Forum section: electronics / beginners

author: Djsajmy
author_rank: Newbie
timestamp: January 10, 2014, 10:09:52 am
content: Hi all!Is there a way to use a remote power outlet switch with the remote and a physical wall switch ?The remote has two buttons (ON and OFF). I would like to be able to control the remote switch with the remote and another physical switch on the wall.Is this even possible ? And if HOW ?

author: Rerouter
author_rank: Super Contributor
timestamp: January 10, 2014, 10:15:58 am
content: The best way is 2 way switching with a local power indicator your on/off really becomes a toggle so unless the wall switch is off will read reversed, but its the second safest way

author: GeoffS
author_rank: Unknown
timestamp: January 10, 2014, 10:20:13 am
content: Do you mean wireless remote controlled power switches? The ones I have, have a button on them so you can turn them on/off without the remote.

author: Djsajmy
author_rank: Newbie
timestamp: January 10, 2014, 10:45:43 am
content: Quote from: GeoffS on January 10, 2014, 10:20:13 amYes, similar but my are without the little switch on them! Would I be able to put a switch on like GeoffS image ?
Remote voltage measurements - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: September 10, 2022, 01:27:41 pm
content: I would like to measure the voltages of some 12v lead acid batteries used in an alarm system without having errors due to the voltage drop in the ground wire powering the alarm panel 20 meters away.I was thinking of putting a micro next to the battery and conveying the voltage measurements via a digital opto isolated link.Is that a sensible idea? What do commercial bits of kit use for this kind of problem.

author: Ian.M
author_rank: Super Contributor
timestamp: September 10, 2022, 01:36:29 pm
content: Run remote sense wiring, fused at 100mA in both the positive and negative wires, right next to the battery terminals for safety, then make a differential measurement at the panel end. If using a digital display it must *NOT* be powered from the sense wires, and must either have fully separate power ground and signal negative, or if they are commoned, be powered from a fully floating isolated supply (e.g. its own transformer secondary or an isolated DC-DC converter).

author: BeBuLamar
author_rank: Super Contributor
timestamp: September 10, 2022, 03:15:57 pm
content: I would use a Fluke meter with Fluke Connect and use an Iphone to monitor the voltage. The phone can also log the voltage. Or I just use the Fluke meter to log the voltage for a day or so and view it to see if at any time the voltage drop. That's a comercial solution I already have.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: September 10, 2022, 08:27:06 pm
content: Use a micro like an ESP32.This will help:https://www.espruino.com/INA226

author: e100
author_rank: Frequent Contributor
timestamp: September 11, 2022, 05:16:07 am
content: Quote from: JustMeHere on September 10, 2022, 08:27:06 pmI already have an INA219 which is similar, but not identical to the INA226.For a remote voltage measurement without ground effects, is it OK to repurpose the differential measurement feature intended for current so it looks like this

author: e100
author_rank: Frequent Contributor
timestamp: September 11, 2022, 04:03:39 pm
content: This seems to work. I'm using the INA219 differential inputs to measure the voltage drop across a resistor in a 1mA current loop and then calculating the full voltage across the battery.[ Specified attachment is not available ]

author: ledtester
author_rank: Super Contributor
timestamp: September 11, 2022, 04:42:21 pm
content: Some questions...Is the 1mA current loop always active? Is it used for anything else?Is the alarm system powered only by the battery or is the battery just a backup power source?What's the capacity of the battery?What microcontroller do you have in the panel?

author: e100
author_rank: Frequent Contributor
timestamp: September 11, 2022, 05:33:07 pm
content: Quote from: ledtester on September 11, 2022, 04:42:21 pmThe panel and network gear consume 20W so the efficiency of the monitoring circuit isn't a concern.The micro will eventually be an ESP32 with wired ethernet to the internet gateway.
Delete Delete Delete - Page 1
Forum section: electronics / beginners

author: The_Almighty_Bacon_Lord
author_rank: Contributor
timestamp: April 15, 2018, 04:04:13 pm
content: Delete Delete Delete

author: David Hess
author_rank: Super Contributor
timestamp: April 15, 2018, 07:31:15 pm
content: Temperature measurement using a PN junction is usually done using the delta Vbe method where the difference in voltage with two different currents which have a fixed ratio is measured. So what you want is a fixed change in voltage at the two currents. We do not know the ratio of currents or absolute values used but my guess is that a low valued resistor, about 60 ohms, will yield about a fixed room temperature result. Adjust the resistance value to get the temperature you want.I came up with 60 ohms from:60mV delta-Vbe / decade of current at room temperature.Typically 1mA is used for the high current and a 10:1 ratio is used.60mV / 1mA is 60 ohms; I ignored the actual ratio since you will need to adjust the value anyway.

author: David Hess
author_rank: Super Contributor
timestamp: April 15, 2018, 08:19:37 pm
content: Quote from: The_Almighty_Bacon_Lord on April 15, 2018, 07:39:06 pmThe 60 ohm resistor replaces the NPN transistor but you can connect it across the PN junction for the same results. With the 60 ohm resistor in place, the PN junction will not conduct anyway.60 ohms is just an estimated value since we do not know the two currents used for the measurement.

author: Brumby
author_rank: Unknown
timestamp: April 15, 2018, 10:32:17 pm
content: Is one of those 3 legs of the transistor not connected to anything?I mean, it may be soldered to a pad - but does that pad go anywhere?

author: SL4P
author_rank: Super Contributor
timestamp: April 15, 2018, 10:36:02 pm
content: Can I ask why you want to fool the PC ?Motherboard monitoring usually fulfills a meaningful purpose.

author: Wimberleytech
author_rank: Super Contributor
timestamp: April 16, 2018, 02:17:30 am
content: Here is an article that explains what Hess is describing:http://www.analog.com/media/en/analog-dialogue/volume-33/number-1/articles/measuring-computer-chip-temps-with-speed-and-accuracy.pdfIf you want to replace the 3904 with a resistor, look to see what chip is processing the deltaVBE and see what currents are being applied. Then calculate the resistor value. The ADM1021A uses 205uA and 12uA thus 0.026*ln(205/12)=74mV ->> 74mV/(205u-12u) = 382 ohms

author: David Hess
author_rank: Super Contributor
timestamp: April 16, 2018, 03:12:26 am
content: Quote from: The_Almighty_Bacon_Lord on April 15, 2018, 09:02:32 pmUsually just one of the junctions of the transistor is used and the other is shorted. Offhand the only company I know of who used all three leads in a slightly different delta Vbe thermometer circuit is Tektronix.Examining the layout or making measurements should reveal which pair of leads is shorted. Or just mount the resistor; you have a 2 out of 3 chance to pick the correct pair and connecting it wrong isn't going to damage anything.
Remove ac ripple from ckt - Page 1
Forum section: electronics / beginners

author: A2
author_rank: Contributor
timestamp: August 05, 2014, 12:38:41 pm
content: 1. I have a board, which is getting +8V from a ac-dc power supply.Input to ac-dc power supply: 220V ac , 50Hz.output of ac-dc: +5V dcNow this output contain noise. What I think it will be 50hz noise from power supply riding over +7Vdc.I have put a 7805 regulator on my circuit which converts +8V to +5V.What capacitor value should I place on regulator which can remove the noise.2. In second case, I have a li-ion battery over which a boost converter is fitted, converted its voltage to +5V dc.It powers my circuit. But since its a boost conveter in contains noise depending upon the its frequency.How to remove this noise.

author: tautech
author_rank: Super Contributor
timestamp: August 05, 2014, 09:13:27 pm
content: It is normal to put up to 1000 uF before a linear regulator to reduce ripple.The boost converter chip datasheet will have recommendations for input and output capacitance.Often high frequency caps will be needed due to the switching frequency used.Multi-layer ceramic or tantalum are usually recommended.

author: Robby
author_rank: Newbie
timestamp: August 06, 2014, 04:43:26 am
content: Let me get this straight: the output is +5v but you are seeing +7v? Is there a .01uf bypass cap where the power leaves and again where it enters the device under test? Are the wires in a bundle with other voltage sources? Did you look at the voltage on a scope and see ripple?EDIT:Are you trying to pull too much current through the supply? Use a larger cap, like 4700uf and the see if the ripple has leveled out.
Remove ground loops b/w coax cables from multi-channel amplifier to oscilloscope - Page 1
Forum section: electronics / beginners

author: l_donini
author_rank: Newbie
timestamp: July 29, 2025, 03:58:13 pm
content: I’ve built a box with several buffer amplifiers, all sharing the same ground and supply rail. Each output travels via a BNC coaxial cable across the lab, and the various cables are each connected to a different channel of a multi-channel oscilloscope. This simple circuit topology creates ground loops between the shields of the various coaxial cables since they all share the same ground at both ends. (The amplifier box itself is not connected to mains earth though, so at least there is no earth loop)I was wondering what a simple solution would be to eliminate the ground loops. Ideally it would satisfy the following requirements:- Still use the same coaxial cables (one per signal), each about 10-20 metres long, i.e. 1000-2000 pF capacitance.- No additional electronics on the oscilloscope side- All amplifiers within the box should be powered from the same rails (positive, negative, ground)- A few MHz bandwidthIn other words, all the complexity necessary to eliminate / suppress the ground loops should be contained within the amplifier box.The best solution I could come up with so far is to use a differential amplifier, which (if I understand it correctly) should allow for a somewhat-floating output provided the load impedance is not too low:My idea is that I could power a few of these from the same rails and the 100k resistors should be enough to break the ground loop. But from simulating such a circuit in LTspice it also seems that at high frequency the suppression goes away – I guess this is due to the limited bandwidth of the op-amp?How could I improve the design of this circuit to get better suppression of the ground loop at high frequency as well?Could I wind each output coax cable / wire pair around a ferrite to increase ground loop impedance at high frequency? How many turns am I likely to need to have an effect down to 10kHz or so?One idea that seems to be discussed quite a lot on the Internet seems to be to drive the output differentially (e.g. with a fully differential op amp). As I understand it, it seems that one would typically drive the two signals more or less symmetrically around 0V. But here I would like to have the shields of all the coaxial cables near 0V, only biased by the externally induced emf. Is this possible at all, and how would I go about setting this up?Thanks,Luca

author: David Hess
author_rank: Super Contributor
timestamp: July 29, 2025, 06:14:44 pm
content: That will work. I have done it myself, although not with an oscilloscope input.The 100k bias return path is not required because the ground at the device and the oscilloscope are connected together in one way or another. The difference amplifier is removing the noise between the two ground connections.
Remove white Text on PCB's? - Page 1
Forum section: electronics / beginners

author: Flunze
author_rank: Regular Contributor
timestamp: September 16, 2012, 04:38:02 pm
content: I wonder, if there is a simple way, to remove the white coding like "R1" or "C1" on the PCB. This is hiding my view over the tracks on a SMD board, which should not be disassambled. Is there a good way?

author: SeanB
author_rank: Super Contributor
timestamp: September 16, 2012, 04:44:52 pm
content: Acetone on a cotton bud normally works well, or Xylene or toulene. All 3 are not good to breath the fumes of, and are quite flammable as well. Take care and do the rubbing in an area with good airflow to the outside to remove the vapours.

author: Flunze
author_rank: Regular Contributor
timestamp: September 16, 2012, 04:48:04 pm
content: Acetone will work? That's nice, because I still got some left. But will it not destroy other parts like plastics on the PCB? I am scared of dissolving my components.

author: SeanB
author_rank: Super Contributor
timestamp: September 16, 2012, 04:59:45 pm
content: Only use on the lettering, so that it is selectively removed. In many cases it will dissolve plastics, but should not affect SM devices that are wave or IR soldered, as these generally use a resin that is quite solvent resistant. Just use on the white, you might find the soldermask underneath will come off as well, so use only in small areas.

author: ptricks
author_rank: Frequent Contributor
timestamp: September 16, 2012, 06:21:40 pm
content: If you are worried about the effects of acetone get some of the non-acetone finger nail polish remover. It isn't as harsh on plastics and smells better too !
Remove/replace transducer on cicuit board - Page 1
Forum section: electronics / beginners

author: THATguy
author_rank: Regular Contributor
timestamp: November 30, 2016, 05:01:48 am
content: Few naive questions.There is a circuit board and it has a vibrator on it (thing you have in a cell phone).Can I just remove it?Do I need to ensure the + & - wires are soldered through - to keep the connection going?What if I replace it with a lower powered one?(obviously I'd test the voltage and attach a resister for my smaller vibrator to protect it).CheersSorry for my silly questions, trying to get my head into electronics mindset.

author: ataradov
author_rank: Super Contributor
timestamp: November 30, 2016, 05:37:56 am
content: If it is indeed a motor like in a cell phone, then just keep it disconnected and you should be fine. Those vibrators are tiny brushed motors, so you can replace them freely as long as nominal voltages match.

author: THATguy
author_rank: Regular Contributor
timestamp: November 30, 2016, 05:57:54 am
content: But will I need the + point to ground out?What happens when the IC/circuit sends the current that way. Will it mess things up?

author: ataradov
author_rank: Super Contributor
timestamp: November 30, 2016, 05:59:49 am
content: Nom just leave them disconnected. When driver wants to turn on the motor it applies the voltage. With motor removed, no current will flow, but nothing bad will happen.
Removing chip but it has blue "film" over it. - Page 1
Forum section: electronics / beginners

author: munkss
author_rank: Newbie
timestamp: December 11, 2019, 09:00:42 pm
content: Hello, I have very small experience with soldering and i was working on this board and was gonna remove a chip to code it. But after opening it up and looking at the board i saw it has been worked on before. And over the chip im removing it has a blue film/glue. I have no idea what it is or how to remove it. Im removing the small 8pin chip.Is it safe to just use hot air to remove the blue stuff+chip?THanks in advance.

author: Gyro
author_rank: Super Contributor
timestamp: December 11, 2019, 09:15:12 pm
content: It looks as if the manufacturer really doesn't want you to remove the key ICs. That is probably some type of epoxy resin. I suspect that removal will not be an easy job as it's there to prevent it.What is the board?P.S. I'm not sure that the board has been worked on before - the flux on the switch pins makes me think that they were hand soldered after smd assembly.

author: munkss
author_rank: Newbie
timestamp: December 11, 2019, 09:25:13 pm
content: Quote from: Gyro on December 11, 2019, 09:15:12 pmHi thanks for the reply, its a instrument cluster im converting and adding some features on. I don't have a picture of the full board. But it has some text on it from a marker and looks like they have repaired some corrosion damage on it before.

author: Gyro
author_rank: Super Contributor
timestamp: December 11, 2019, 09:30:24 pm
content: Welcome to the forum btw.If it's from an instrument cluster then I can understand the epoxy. It probably contains Odometer information.Ah ok. Corrosion damage repair I can understand.

author: munkss
author_rank: Newbie
timestamp: December 11, 2019, 09:37:21 pm
content: Quote from: Gyro on December 11, 2019, 09:30:24 pmYeah that what i was thinking, Either they repaired it before and put something on it to prevent more corrosion or its factory and they don't want you to remove it. Ill try to clean it with some acetone tomorrow to see if it dissolves or worst case is i have to grind it off. Again thanks for the reply and welcoming

author: Bud
author_rank: Super Contributor
timestamp: December 11, 2019, 11:17:54 pm
content: I remember seeing a video of a similar resin over a chip, just black color, and the guy used a hot air gun to heat it and it became brittle and came off with some scraping.

author: andy3055
author_rank: Super Contributor
timestamp: December 11, 2019, 11:29:39 pm
content: It could be to prevent effects due to vibration. You can try heating as suggested above. If you try any solvent like thinner etc. make sure to try it in a corner so that you don't remove any text/markings on the board and/or other parts.
Removing Conformal Coating - Page 1
Forum section: electronics / beginners

author: jerryk
author_rank: Regular Contributor
timestamp: February 18, 2019, 12:08:08 am
content: I have a marine spec inverter that I'm working on and all circuit boards are covered in conformal coating. I would like to remove all the coating on most of the boards. IPA softens the coating but is slow to work with. I have used acetone on the back sides of a couple of boards using a tooth brush to work the coating off. So far this is most effective but I would prefer to avoid such a harsh method for the smd side of the boards. Can I soak a circuit board over night or longer in IPA or IPA/Acetone mix without damage to the board are components?Any suggestions on completely stripping these boards would be appreciated.Jerry

author: GopherT
author_rank: Contributor
timestamp: February 18, 2019, 12:30:18 am
content: Acetone will soften and eventually dissolve the adhesive that bonds the copper traces to the FR4 board. You can try ipa over night but I would not get acetone into the story until you are sure ipa is not doing the trick.Do you know what type of coating it is?Conformal coating thickness requirements are in accordance with IPC J-STD-001 for the following coating types:Type AR Acrylic Resin 0.00118 to 0.00512 inType ER Epoxy Resin 0.00118 to 0.00512 inType UR Urethane Resin 0.00118 to 0.00512 inType SR Silicone Resin 0.00197 to 0.00827 inType XY Parylene Resin 0.000394 to 0.00197 in

author: KaneTW
author_rank: Frequent Contributor
timestamp: February 18, 2019, 12:32:43 am
content: I've used a special conformal coating stripper to remove urethane coating. Tried burning it off with a soldering iron in a fume hood at first, but that didn't go anywhere. Solvent got it out with no effort.

author: jerryk
author_rank: Regular Contributor
timestamp: February 18, 2019, 12:47:10 am
content: No idea on the coating type. It softens with IPA is the only real evidence that I can grasp. Heat with hot air rework station and I can peel it with limited success. The problem with IPA and a brush is it gets quite gummy and seems to hold that gummy state for awhile. Acetone is effective using a stiff brush but still is a lot of work on the back sides of headers or any thing that's busy with tht components. There is a lot of places for this stuff to hide so a prolonged soak seemed like a good idea but don't want the board to delaminate or the like. Other concerns are inductors and transformers and the way they are wrapped. I can't seem to strip that wire when I try but don't want to violate the windings in any way.Jerry

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 18, 2019, 12:58:10 am
content: If it's acrylic then I think you need THF. I've done a bit of this recently, actually; the pen we got is basically 100% THF -- same stuff used for PVC cement, by the way.Tim
Removing excess solder from a joint? - Page 1
Forum section: electronics / beginners

author: JCam
author_rank: Newbie
timestamp: April 30, 2020, 12:07:09 am
content: Hi folks. I'm new to this forum so please direct me elsewhere if I'm positing in the wrong section!As well as being new to the forum I'm fairly new to soldering, and I seem to be having an issue when trying to remove excess solder from my joints.I try and tin the tip of my iron with a little 63/37 solder and press it against the joint in hopes to suck-up the excess, but that just seem to add more solder. I've also tried going in with a clean tip and sucking some solder up but that just seems to make the solder go uneven and rough?I've attached a photo of my awful workAny help would be kindly appreciated.FYI - My iron is a Hakko FX-888D with my temp sitting at 390C.Kind regardsJames

author: langwadt
author_rank: Super Contributor
timestamp: April 30, 2020, 12:18:05 am
content: solder wick

author: JCam
author_rank: Newbie
timestamp: April 30, 2020, 12:35:44 am
content: That was extremely helpful! Thank you very much.

author: Shock
author_rank: Super Contributor
timestamp: April 30, 2020, 12:55:44 am
content: Solder wick and also a hand solder sucker can be used if it's not too small. For very small solder bridges some flux and a clean tip will correct them and clean up the joint.

author: PixieDust
author_rank: Frequent Contributor
timestamp: April 30, 2020, 08:25:29 am
content: Also, don't hold the soldering iron on the pads for long otherwise your pads will delaminate. Probably no more in the worst case of 5 seconds, but generally try to be as quick as possible, I'd say around 2 seconds would be ideal.From memory, I use around 360 for temps. Have a search around for temps, yours seem a tad high.

author: tooki
author_rank: Super Contributor
timestamp: April 30, 2020, 12:55:34 pm
content: Quote from: Mechatrommer on April 30, 2020, 12:19:50 amQuote from: JCam on April 30, 2020, 12:35:44 amJust a little heads up that that youtuber, in all his soldering videos, has the bad habit of going back to “touch up” almost every joint, often multiple times, mostly totally unnecessarily. Flux makes it possible for that to work at all, but basically, the longer the solder is heated (cumulatively), the more “overcooked” and uncooperative it gets. So if a joint is imperfect but acceptable, better to just leave it be.