hybridfree/eevblog-posts huggingface dataset:
Shared Library of circuit sim files? - Page 1
Forum section: electronics / beginners

author: mikeinfodoc
author_rank: Regular Contributor
timestamp: October 25, 2017, 08:38:40 pm
content: I have and use LTSPice and NI's Multisim circuit software simulators.Does anyone know of a website where there are downloadable prebuilt circuit sim files (for either of the products above)?Sort of like a GitHub, but containing a library of prebuilt, commonly-used circuit sim's (such as some simple/standard/common circuits such as buck/boost/schmitt/etc)For example, somewhere in which I could download sample circuits which others have built and tested.Currently, I am hoping to find some schmitt comparator circuit sims, as my feeble attempts to get desired results from my created sim files are not working as I desire.

author: danadak
author_rank: Super Contributor
timestamp: October 26, 2017, 11:04:58 am
content: Most spice vendors have some standard examples in their tool. As well as semiconductorvendors with their own tools and examples. Both online tools and offline. No centraldatabase I am aware of covering the industry.For example ON Semi has downloadable tools and examples for a numberof parts, including various regulator architectures. Same for TI,(Tina TI)....http://www.onsemi.com/PowerSolutions/support.doRegards, Dana.

author: mikeinfodoc
author_rank: Regular Contributor
timestamp: October 31, 2017, 10:52:20 pm
content: I found some useful open circuits online here:https://www.multisim.com/content/kwwhp3PBMfgfDuRBy37rSF/schmitt-trigger/open/They also let you run/simulate the circuit and show scope results.
Sharing a UART with an FTDI chip and a bluetooth module? - Page 1
Forum section: electronics / beginners

author: networkingdude
author_rank: Contributor
timestamp: September 22, 2012, 06:52:37 pm
content: I'm working on a project that needs to have multiple ways to connect to the micro controller. My question is what would be the most cost effective way to achieve this?I'll be using a FTDI rs-232 device and a bluetooth module. Can i just selectivity cut power to each or will this cause some issues?Thanks for the advice!

author: 8086
author_rank: Super Contributor
timestamp: September 22, 2012, 07:14:44 pm
content: Are you short of pins on the microcontroller? You could use soft serial for one of them if it's not too fast.

author: networkingdude
author_rank: Contributor
timestamp: September 22, 2012, 07:52:28 pm
content: There are no options to use other pins. It's a STN1170 OBD-2 IC

author: 8086
author_rank: Super Contributor
timestamp: September 22, 2012, 07:54:25 pm
content: Ah. In that case use a multiplexor IC. I assume you don't need to have both in operation initally, or both listening, before deciding on one to use?

author: networkingdude
author_rank: Contributor
timestamp: September 22, 2012, 07:57:26 pm
content: Thats right only one active at a time. Could I just switch the power to the FTDI and the bluetooth module?
Sharing an amplifier audio input with a Y-splitter ? - Page 1
Forum section: electronics / beginners

author: John_Edward
author_rank: Contributor
timestamp: December 08, 2014, 02:34:39 pm
content: tl;dr:Can I use an Y-splitter to connect a Turntable and a TV to the same input on a hifi system ?Should I set the Turtables pre-amp on or off ?---So, my grandmother has theOnkyo CS-254BThifi system, which has just one 2xRCA audio input at the back, which is currently connected to her TV (using the TVs headphone connection)I happened to get aSony PS-J20turntable I'm planning to give her for christmas.This turntable has an internal pre-amp you can select from the bottom.If I get/make a Y-splitter cable to connect these both to the same input, would it work ?There is a real possibility she will try to use them both at the same time, will this break something ?I know there are inexpensive selector boxes available, but if I get her one, she _will_ call me twice a week asking why her TV doesn't have any sound, so...
Sharing Button input between two microcontrollers - Page 1
Forum section: electronics / beginners

author: 24602
author_rank: Contributor
timestamp: June 26, 2023, 12:03:26 pm
content: Hi AllIve got a project with two microcontrollers (redundancy)Button connected to both microcontrollers. Internal pull-ups on the micro inputs. Button goes to GND when closed. This works but not ideal.What would be the best way of sending that button signal to both controllers in the event that one micro dies or shorts the input HIGH or LOW?

author: Jeroen3
author_rank: Super Contributor
timestamp: June 26, 2023, 12:04:52 pm
content: Simple 74 series buffers/inverters with a series resistor at the ouputs.

author: Damianos
author_rank: Frequent Contributor
timestamp: June 26, 2023, 08:06:52 pm
content: Two diodes with the cathodes connected to the button and the anodes, via resistors in series, to the inputs.

author: 24602
author_rank: Contributor
timestamp: June 28, 2023, 02:52:35 am
content: Like the attached image?

author: Shonky
author_rank: Frequent Contributor
timestamp: June 28, 2023, 02:59:32 am
content: Quote from: 24602 on June 28, 2023, 02:52:35 amYour diagram has the cathodes going to the switch.

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 28, 2023, 03:28:01 am
content: You don't even need any diodes.Change resistor values to your preference. Keep R1/(R2||R3) small enough to make sure the common point still above VIH(MIN)when one of the IO stuck low. Beware of "always on" internal pullup like STM32's 40kΩ on reset pin, picking a too high value for R2 and R3 may cause IO pin to not go low enough below VIL(MAX)when needed.It was for reset circuit so you probably also don't need the caps, although it's still nice to have for debounce.

author: Gyro
author_rank: Super Contributor
timestamp: June 28, 2023, 10:50:35 am
content: If you want true redundancy, you might want to go for a double pole push button. It might limit your choice a bit but the button contacts are probably one of the less reliable elements in the system.

author: DarkMode
author_rank: Contributor
timestamp: June 29, 2023, 08:04:32 am
content: Howdy, from my basic understanding, if the Button Pulls Low (Ground), and the Micro's are both pulling up 'High'. Pushing the Button will draw energy from BOTH pins of the Micro.I think they will both 'short' and flow the energy to the Ground (via the button), you might have to add a resistor after in the circuit to stop it from Shorting too quickly, but that's my Guess.Corrections welcome
Sharing SPI bus - Page 1
Forum section: electronics / beginners

author: Silenus
author_rank: Contributor
timestamp: January 08, 2015, 12:36:01 am
content: I am designing a MCU embedded system using an AVR and I need the SPI bus for a wifi module. However, I also need this bus to program the chip via ICSP headers. Will having the wifi module on the same bus cause any ill effects when I program my chip? or should I go for a MCU that has two SPI buses?

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: January 08, 2015, 01:19:17 am
content: SPI is a master slave bus where usually the MCU is the master. A slave must not do anything on the bus if its chip select is not active. So given the CS line is deactivated during reprogramming the WiFi module should not be an issue.

author: LukeW
author_rank: Frequent Contributor
timestamp: January 08, 2015, 04:24:51 am
content: In this case it can be worthwhile to put a pullup on the peripheral device !CS line, to stop it going low or getting into a funny state during microcontroller programming.
Sharp System W30H Stereo CD not Working - Page 1
Forum section: electronics / beginners

author: Asterix
author_rank: Contributor
timestamp: August 16, 2020, 05:50:50 pm
content: Hi there mates!Recently i was thrift shopping.And i found myself a Shar Stereo system with some nice speakers.The model is: "SYSTEM W30H(BK)". It said tested but cd wont open.I managed to replace the string on the disk opening mechanism.Wich fixed that problem and now the drive opens up and i can put a disk in it.However it wont read the CD.The display stays at 0 minutes andzero seconds wich makes me believe because the disk does actually spin there is an error reading the disk.The disk/CD plays in another stereo alright and the problem happens with any CD.Does any of you know how to fix this? Could u help me? i really love the look of the stereo...Regards,Asterix
Shematics - Page 1
Forum section: electronics / beginners

author: Hexenbyte
author_rank: Newbie
timestamp: July 19, 2018, 11:33:50 pm
content: Hi everyone, i am a beginner in electronics, and i am learning from the book The Art of electronics Third Edition, as a complement, i am looking for a book on how to read schematics, analog and digital, this will be helpful for when i want to fix computer motherboards such as macbook's and pc motherboards that i can lay my hand on schematics to read an be able to fix them.Any suggestions on which book i should read? thank you very much in advanced.

author: Cliff Matthews
author_rank: Unknown
timestamp: July 20, 2018, 12:27:09 am
content: Welcome y Bienvenido!Schematicsymbols are fairly standard and often power supply areas are placed to the left, but there are many unique features and link-points you'll see to help you visualize the device you are working on. You'll find lots of free resources all over this forum. I'll try and post a few..1) Use the forum searchhttps://www.eevblog.com/forum/search/?advanced;search="reading%20schematics"2) Check educational resourceshttps://www.eevblog.com/forum/other-blog-specific/a/msg1341170/#msg13411703) Check Electronics Primershttps://www.eevblog.com/forum/beginners/electronics-primers-course-material-and-books/100/4) Check YouTube Spanish channels that link to good resourceshttps://www.youtube.com/user/bourlotg/videos(este mismo tiene una serie de videos llamado "Promocion de canales emergentes")*edit - Oops! Se me olvido.. Saludos de Canada!

author: Hexenbyte
author_rank: Newbie
timestamp: July 20, 2018, 01:48:30 am
content: Thank you very much, saludos, pura vida, gracias por los links.
Shield in connectors - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: March 04, 2024, 04:59:51 pm
content: This is regarding the purpose of what is called as "shield" in connectors?I want to understand why do we need "shield" in connectors and why is it required?I happen to go through ethernet and saw the RJ45 connectors which has shield.I read that the shield is just the outer metal casing of the RJ45 connector. But how it is connected to the chassis ground, I am not sure. Also, why it is required?

author: selcuk
author_rank: Frequent Contributor
timestamp: March 04, 2024, 07:51:58 pm
content: The shield is the chassis part closest to the conductors inside the connector. Of course, you should bond it to the chassis to make it its part. It helps redirecting transient fault currents to the chassis ground. It decreases the emissions from the circuit by providing a good bonding with the chassis and the connector.Some ethernet connectors have flexible fingers. Those are for making a reliable bond with the chassis. You may also connect the shield to the PCB ground via its leads. But using only PCB leads doesn't result in a reliable 360 degree bonding.If you want to know about connecting the ethernet shield to the circuit ground, you may refer to Figure 17 and Table 5 on the below document. It shows EMC measurements for direct ground connections vs. capacitor, resistor, varistor etc.https://www.we-online.com/catalog/media/o721297v410%20ANP116_Gigabit-Ethernet__EN.pdf
Shielded cable that cannot be grounded - Page 1
Forum section: electronics / beginners

author: pcblearner
author_rank: Contributor
timestamp: April 22, 2015, 01:19:00 am
content: HelloHere is a newbie question... I want to use a cable for some signal lines (I2C to be exact) and since this cable goes between boards, I would like the cable to be shielded. Now, my understanding is that if the shield of the cable is not connected to signal ground, it can actually behave as an antenna (as EMI can induce voltages on the shield) which is bad.So, why is it that when I look at cables like this:http://www.digikey.com.au/product-detail/en/30-00279/T1247-30-ND/4581653There is clearly a shield, but I cannot see any way to actually connect to the ground... I am wondering if I am missing something here...Thanks

author: sparx
author_rank: Contributor
timestamp: April 22, 2015, 01:21:45 am
content: Afaik the connector jacket may make a physical connection to the shield (Such as the case with satellite coaxial cable and F connectors do), or may accept a soldered connection to connect the shield?

author: PeterFW
author_rank: Frequent Contributor
timestamp: April 22, 2015, 01:56:44 am
content: Quote from: pcblearner on April 22, 2015, 01:19:00 amThere are soooo many different ways to connect the shielding of a cable, i guess you mean the "braidet copper" part around the main conductors.Depending on the connector the shield makes the connection though a press fit, crimp or you untangle it, put shrink wrap over it and treat it like a 4th conductor.Here is a picture:https://robrobinette.com/images/Audio/Canare_Star_Quad_Cable.JPG

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 22, 2015, 02:24:50 am
content: The shield (whether it is braided or simply spiral-wapped) is simply "unraveled" and twisted together as its own wire. Then you connect it just as you would any of the inner wires.

author: pcblearner
author_rank: Contributor
timestamp: April 22, 2015, 02:46:59 am
content: Thanks everyoneI understand now.

author: KeepItSimpleStupid
author_rank: Regular Contributor
timestamp: April 22, 2015, 03:10:04 am
content: Unraveling, is the wrong way to do it. You actually make a hole in the shield by pushing the braid aside and then pull the center conductor through that hole unless the cable is such that it's so poorly designed it won't allow that.
Shift Register Configuration - Page 1
Forum section: electronics / beginners

author: ryanmills
author_rank: Unknown
timestamp: April 28, 2022, 08:58:31 pm
content: Datasheet:https://www.ti.com/lit/ds/symlink/sn74ls243.pdfI need to take 3.3V Logic to 5V logic one way, looking at a SN74LS243DR. With the A side being 3.3V going to the B 5V side and looking at page 1 of the datasheet I think GAB and GBA inputs both are set low so its A to B? I don't understand what latch and isolation would be? I assume I would not want those modes? Or would latch or isolation also work?

author: ledtester
author_rank: Super Contributor
timestamp: April 28, 2022, 10:02:38 pm
content: I think latch mode works this way...First suppose you have /GAB = L and GBA = L and present some data on the A lines. That data will be seen on the B-lines.Then you set GBA = H. The data is now "latched" in the sense that you can set your A lines to hi-Z and the data will still show up on the B-lines.

author: ryanmills
author_rank: Unknown
timestamp: April 28, 2022, 10:41:59 pm
content: Ahh yeah that makes sense. I guess end of the day I just need A to B.
Shift register question - Page 1
Forum section: electronics / beginners

author: jmctech
author_rank: Contributor
timestamp: May 11, 2015, 05:44:01 am
content: I am starting a new project, with each one I try to add parts that I have never used. I am going to be using (3) 74hc595n shift registers on it. I looked through the data sheet and could not find if the latch pin requires a pulldown resistor. Will this pin tend to float? It is being controlled from an atmega328 with the arduino boot loader.Thanks,Jason

author: Skimask
author_rank: Super Contributor
timestamp: May 11, 2015, 05:49:49 am
content: Depends what the initial state of the pin driving the latch pin is.If there's a possibility it'll float, especially during that first few u/sec while the chip is booting up, then yes, use a pulldown.Either way, a weak-ish pull down isn't going to hurt anything unless you can't pull it back up with the Arduino.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2015, 05:51:58 am
content: Any CMOS logic input will tend to float if there is no driver for it.Exceptions include "bus hold" type inputs, which actually provide a small internal driver to address this. However, the initial state will be undefined, so a pull-up or down might still be useful.The ATMEGA pins will be open circuit (tristated, floating) until the software asserts them, so a default state should be provided with a pull resistor. Not strictly necessary, because it doesn't affect operation (presumably, nothing is operating while the MCU is in reset), but still a "nice to have".The same applies to the ATMEGA pins themselves: they should be pulled, or assigned a default state. Usually, the internal pull-up provides this without external components (all unused pins, DDRn = 0 and PORTn = 1), easily done.Tim

author: jmctech
author_rank: Contributor
timestamp: May 11, 2015, 05:52:58 am
content: Thanks for the reply, I will put a 10k on it to be safe.

author: Zero999
author_rank: Super Contributor
timestamp: May 11, 2015, 10:00:00 am
content: If you really want to avoid this then you could go for the LS version which will default to high on the inputs but HC is better and will be available much further into the future, than LS which is slowly dying.
Shift registers, 74LS299 vs 74LS595 - Page 1
Forum section: electronics / beginners

author: SharpEars
author_rank: Unknown
timestamp: November 11, 2015, 04:59:35 pm
content: Is the '299 just a more powerful version of the '595, allowing both inputs and outputs on its parallel pins? I am trying to figure out what the differences between these chips are.

author: retrolefty
author_rank: Super Contributor
timestamp: November 11, 2015, 05:10:30 pm
content: Quote from: SharpEars on November 11, 2015, 04:59:35 pmYes, basically the 299 can do what a 595 does and more. The datasheets for both devices is where you go to ask these kind of questions.

author: SharpEars
author_rank: Unknown
timestamp: November 11, 2015, 06:05:11 pm
content: Quote from: retrolefty on November 11, 2015, 05:10:30 pmThanks for confirming, so the '299 is a superset of the '595.

author: retrolefty
author_rank: Super Contributor
timestamp: November 11, 2015, 06:10:25 pm
content: Quote from: SharpEars on November 11, 2015, 06:05:11 pmYes, at a functional level, but to replace a 595 with a 299 in an existing circuit or board would take careful study of the datasheet as they are not pin for pin compatible.

author: Ian.M
author_rank: Super Contributor
timestamp: November 11, 2015, 07:00:46 pm
content: I beg to differ. The '595 has an output latch. That means you can shift new data along a chain of them without disturbing the current data on the parallel outputs, then transfer the new data to the output latches of all the chips simultaneously. The '299 has its tristate output buffers directly connected to the shift register, so new data ripples along from one to the next, pushing the old data dow the chain as it goes. If you are driving a lot of outputs at a high update rate, and need to avoid glitches, the '595 is vastly preferalbe.

author: SharpEars
author_rank: Unknown
timestamp: November 11, 2015, 07:55:58 pm
content: Quote from: Ian.M on November 11, 2015, 07:00:46 pmInteresting, but the '595 has no load functionality from the parallel outputs (i.e., convert them to inputs for a parallel load) from what I can tell. Is there a 74LS that takes the desirable qualities/features of both in one chip?

author: oPossum
author_rank: Super Contributor
timestamp: November 11, 2015, 08:19:45 pm
content: SPI I/O expanders (Microchip MCP23S08 and many others) allow the I/O pins to be configured as input or output and behave much like a shift register. Sort of a superset of what the 74299 can do.These chip are all CMOS rather than TTL. Do you really want TTL?

author: SharpEars
author_rank: Unknown
timestamp: November 11, 2015, 08:33:07 pm
content: Quote from: oPossum on November 11, 2015, 08:19:45 pmWell I do want 5V support, so if they go that high, that might be fine. I'll take a look.
Shift registers, and switching pos vs neg side. - Page 1
Forum section: electronics / beginners

author: Barnys1
author_rank: Newbie
timestamp: October 29, 2016, 04:20:22 am
content: HiI have been considering using an Audrino, Pi etc to switch a few relays and had settled on a shift register (e.g. 74HC595) coupled to a ULN2803 which (as I understand it) controls the relay by switching the neg side of the relays coil.However, I have access to some (cheap) 5V, 403mW, 2 coil latching relays (RT424F05) which have the coils sharing a common ground.http://www.alliedelec.com/m/d/ac6e4de0241f77689527aa59e6c4b307.pdfI have fond countless examples of people achieving shift register switching by controlling the neg side of the “to be switched“ components, but I have found surprisingly little on shift register being used to switch a circuits pos side.Is there something similar to the ULN2803 that I could use to switch the pos side of the relay coils?Also, in my limited understanding, I thought that all things being equal, it is better to place a switch on the positive side of a circuit, is this correct?Regards.

author: matseng
author_rank: Frequent Contributor
timestamp: October 29, 2016, 09:38:43 am
content: According to the datasheet the 2-coil version have the A3-terminal as a shared power, not a shared ground. So you should be able to continue using the ULN28xx.

author: Ian.M
author_rank: Super Contributor
timestamp: October 29, 2016, 09:46:47 am
content: If you really need a high-side equivalent to the ULN2803, look at theMIC2981.

author: David Hess
author_rank: Super Contributor
timestamp: October 30, 2016, 04:51:24 am
content: Low side switching has the advantage of easily using NPN bipolar or n-channel MOSFETs which are more economical than their PNP and P-channel counterparts.
Shift sensor output voltage up/down - Page 1
Forum section: electronics / beginners

author: fsky
author_rank: Contributor
timestamp: August 29, 2015, 11:05:30 am
content: Hello!I interfaced a sensor badly on my board and I have to fix it : (I have an output voltage from a current sensor. It's output swing is as follows:VCC/2 for no current,VCC for full current.How to shift those voltages to an differential ADC input, where I would like to get 0V for no current and 2,048V for full current? I want to discard anything below VCC/2. VCC = 5V. I can source a couple hundred mA from output (it's op-amp buffered).Any suggestions for doing it in a simple way and not loosing those important mV above VCC/2?Is a solution using an op-amp as here on page 25:http://www.microchip.com/stellent/groups/SiteComm_sg/documents/DeviceDoc/en542976.pdfa good choice?

author: Simon
author_rank: Unknown
timestamp: August 29, 2015, 11:57:02 am
content: yes something like that.
Shimano Steps power brick - 4pins (how to check working condition?) - Page 1
Forum section: electronics / beginners

author: gronn-overledning
author_rank: Contributor
timestamp: February 09, 2023, 10:51:47 am
content: I dont have the bike. Just want to check if its working.No voltage on either 4 pins.Do I have to short something to activate, or is it just dead?(how to short some of the pins, to activte the voltage...?)Thanks...Shimano Steps charger SM-BCE60https://duckduckgo.com/?q=sm-bce60++shimano+steps+psu&iax=images&ia=imagesConnectorhttps://greatebike.eu/uploads/products/3098/big/nabijecka-shimano-steps-sm-bce60-1.jpg

author: m k
author_rank: Super Contributor
timestamp: February 14, 2023, 02:12:47 pm
content: Many times chargers have a battery temperature check, that's one or two pins.Tall one is probably GND.You can connect a dummy load between charge pin and GND, but there can be a current problem.Your dummy load must survive the startup current.It's also possible that initial battery voltage must be present.There the idea is that only healthy enough battery is charged.Nowadays its also possible that charger and battery have embedded MCUs.In that case you're pretty must out of the loop.charge pin|resistor -<- diode - voltage source|GND GNDtemp +|resistor|temp -

author: gronn-overledning
author_rank: Contributor
timestamp: February 20, 2023, 02:18:12 pm
content: Thanks.By trying to short the two middle pins and "feeding" 30V DC on the charging-terminals, i got the output to make 40V in short "blinks".Could not make it 40+V stable, but the orange LED blinked also....so I guessed the PSU was OK.Made an sales-ad, telling about my testing, and got it sold for an OK price, by someone having several chargers/batteries.
Shive Wave Machine - Page 1
Forum section: electronics / beginners

author: bernie
author_rank: Contributor
timestamp: December 03, 2012, 12:54:37 am
content: Saw this on Hackadayhttp://hackaday.com/2012/12/02/retrotechtacular-similarities-of-wave-behavior/and thought it was good explanation of SWR by AT&T from 1959 - very retro demo

author: Shuggsy
author_rank: Regular Contributor
timestamp: December 03, 2012, 04:34:39 am
content: Very, very cool! Definitely got me thinking about waves in different ways than before. Loved the Shive wave machines that he used -- very good visual demonstration of the behavior of waves in general.
Shop remodel. - Page 1
Forum section: electronics / beginners

author: Radio Tech
author_rank: Frequent Contributor
timestamp: April 15, 2013, 10:27:55 pm
content: About the only place to post this so here goes.My wife dares not to come out in my shop. She calls me a hoarder lolWell I closed down this week end and thought it was time to do a make over. My shop has 3 rooms all open to each other but seperated by work benchs and stuff.Seems my benches were not very funtional and each had a chair to sit in and get lazy. So tearing out each room at a time. Here is the begining of the first room that will be my main repair area. Still have the ceiling to put back in as soon as the wires are tied down. Going to set up a seperate area to test stuff in next.So much to do....

author: blasto9000
author_rank: Contributor
timestamp: April 16, 2013, 06:00:12 pm
content: Love your gear!Is that a Heathkit single-input oscilloscope on the far left, and a 1950s-1960s era radiation survey meter on the right?

author: Radio Tech
author_rank: Frequent Contributor
timestamp: April 16, 2013, 06:46:47 pm
content: Quote from: blasto9000 on April 16, 2013, 06:00:12 pmThanks, took a while to get all that.Most bought non working and repaired. All but the IFR 1200s. That was 9 grandQuoteThe scope is a Bell and Howell schools. But was made by Heathkit for them.I had to look twice when you said radiation meter lol.Guess you are talking about the white meter and blue meter on the bench. Those do look like radiation meters now that you said that. The blue meter is a Bird RMS RF watt meter to 500 watts. The white one was made for Telewave by bird.

author: ivan747
author_rank: Super Contributor
timestamp: April 16, 2013, 08:22:07 pm
content: My bench is never going to be as clean as that. In fact it never was, even right after it was built!So you can do electronics with that gear? It looks old, I wonder if you run into their limitations often.I'm guessing you are a radio tech. Higher resolution photos would really help me to see what cool gear you got.I see you are an RC fan, I always wanted one of those planes but I end spending my money on something else.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: April 17, 2013, 02:00:33 am
content: Quote from: ivan747 on April 16, 2013, 08:22:07 pmTrust me, if you saw rest of the shop you would wonder how I get in the door. But I am planning on making the whole shop look this clean.QuoteFor many many years. And you are correct, I am a radio tech. Mostly communication gear as in marine, business band, cb radio and ham radio. I restore old tube type gear which is most of what I do. Most of the equipment is old yes. But works like a charm. The Owon DSO is brand new btw. I am not getting more involved is microcontrollers. This is one reason for the shop make over.Oh. low res on the camera hides the flawsQuoteI love RC planes. I have 13 here. My biggest is a piper J3 cub quarter scale. In fact I have 3 pipers from small to large. A few stunt planes called the big stick, and several trainer planes.
Shops to buy Oscilloscope near Jackson Height NY - Page 1
Forum section: electronics / beginners

author: sbdada
author_rank: Contributor
timestamp: January 20, 2018, 09:54:30 am
content: Hello, sorry for off topic.Does anybody here from New York? Specially near Jackson Heights?I want to buy an Oscilloscope. one of my relative is currently there, but he doesn't know where he can find it. I don't want to buy it from online as it'll take at-least couple of days to get the scope and he's going to return tomorrow or the next day.Can you guys please help me to find a physical shop near Jackson Heights from where I (I mean he) can buy it today.The scope model is: Rigol DS2102EThanks in advance.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 20, 2018, 10:31:12 am
content: You'd be hard pressed to find many cities in the world that you can walk in and buyanyscope these days, let alone a specific model.Even less so on a Saturday when trade-oriented places will often be closed.

author: sbdada
author_rank: Contributor
timestamp: January 20, 2018, 11:07:53 am
content: I didn't understand what you've said. The model is: Rigol DS2102E @mikeselectricstuff

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 20, 2018, 11:14:16 am
content: I'm saying that it is highly unlikely that you will find a retail shop anywhere that stocks any oscilloscope, therefore even less likely you will find a specific model.There will probably be some online suppliers that can deliver next day. Which is why retail is dead for specialist items like test gear.

author: sbdada
author_rank: Contributor
timestamp: January 20, 2018, 11:31:45 am
content: Oh! got it now.anyway, after some query on internet, i got some online shops near that location. right now, they'r closed. i'm gonna call them at their morning. hope they can deliver it by tomorrow.And yes, thank you again Mr. Mike

author: james_s
author_rank: Super Contributor
timestamp: January 23, 2018, 07:58:44 pm
content: If there's a Fry's around they might have it. That's the only retail store I know of that have oscilloscopes.

author: ikrase
author_rank: Regular Contributor
timestamp: January 23, 2018, 08:41:24 pm
content: Yeah, Fry's sometimes has oscilloscopes, as do surplus stores - but is not usually a walk-in item.

author: Rick Law
author_rank: Super Contributor
timestamp: January 24, 2018, 01:56:49 am
content: Quote from: blueskull on January 20, 2018, 11:55:29 amJust checked - Micro Center has a store in Flushing NY. #7 subway will get you there.Flushing is/was a good place for all kinds of shopping in that area of NYC.

author: nanofrog
author_rank: Super Contributor
timestamp: January 24, 2018, 02:55:00 am
content: I'd suggest ordering it from TEquipment.net (here) as they've 179 in-stock at the time of posting this, and it ships from NJ.So even if you skip overnight shipping (standard shipping is free for $99 orders), it would still arrive to your relative's address quickly.PM sent, and good luck.
short circuit protection for variable power supply - Page 1
Forum section: electronics / beginners

author: glinjik
author_rank: Regular Contributor
timestamp: March 28, 2022, 07:17:14 pm
content: hi so I've been working on my variable power supply and was thinking it would be a good idea to add short circuit protection i had a look through past posts and had a hunt through the internet the simplest variation seems to be a relay my question is1.if the voltage output of my supply is set to 1v wil the relay work?2.is it sensible to use a voltage regulator to supply the relay (the regulator would be burning hot if supply is 30v and output is set at 1v)3.is there a way to do this via transistors?

author: pqass
author_rank: Super Contributor
timestamp: March 28, 2022, 07:42:04 pm
content: If you're thinking about short circuit (and thermal) protection for your standard 780x or LM317 regulators, it's already built-in. See datasheet.If you're thinking about making a CV, CC power supply from discrete parts (transistors, op amps), the CC part takes care of that. See:http://powersupply.blogs.keysight.com/2012/07/how-does-power-supply-regulate-its.htmlFurther,if you're thinking that a 1V output is like a short. It isn't. You're asking the regulator to turn all the voltage from the unregulated side down to 1V into heat (at the output current). Two ways to reduce the heat is to lower the difference between unregulated side and regulated side by (1) switching in lower-voltage transformer taps or (2) use a buck converter pre-regulator.https://sound-au.com/articles/preregulators.htmAnd,the power for the power supply components (for op amps, over voltage protection, tap switching, etc.) is usually provided from the unregulated source with its own fixed regulator(s) (if needed) or via separate transformer secondary. It is not fed from the regulated output of the main regulator since the main regulator may be commanded to go down to 0V (CV or as a result of CC). You can't pull yourself up by your own bootstraps.
Short forms - Page 1
Forum section: electronics / beginners

author: D_K99
author_rank: Newbie
timestamp: October 05, 2015, 11:39:54 am
content: Hey guys,I have found a broken GPS Bluetooth Reciever and there are some testpoints on it taht are named. Now I wonder what they mean. It says "BVDD", "RXD, "TXD", "CTS" and "RTS" does someone know what it all means?

author: Deathwish
author_rank: Unknown
timestamp: October 05, 2015, 12:04:34 pm
content: BVVD = BUS VOLTAGERXD = RECEIVE DATATXD = TRANSMIT DATACTS = CLEAR TO SENDRTS = READY TO SEND

author: D_K99
author_rank: Newbie
timestamp: October 05, 2015, 12:09:30 pm
content: Oh thanks.
Shorted a via to ground just trying to add a wire ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: July 22, 2022, 06:12:45 am
content: I was using the common Hakko 65W iron, to solder onto a mobo 12V rail, and I choose an "empty" via, with a cap that was never installed. But there was some non-leaded solder in it, that my little test wire could not breach. And I never pre-heated the PCB, so with it at 860C, I was adding/removing 60/40 solder with copper braid. I should have used a stronger wire, and poked it tho.The PCB looked fine, I never scratched it or burnt it, but I shorted the via to gnd somehow. I'm wondering if it was internally, on the power/gnd planes. I'm pretty sure it wasn't just on the top surface, the gnd via for the cap was 1-2mm away, and I was using weak flux, that never gives me issues.But I managed to clear it, a few ohms at a time, back to normal, after using a bunch of strong flux (that can leave a nasty conductive goo) and copper braid.The point of this ramble is, did I use too much heat, or is there some little gnd ring, around via's sometimes, or does solder just get under the edges sometimes ? Or in general should u avoid soldering to via's in multilayer PCB's ? I should pre-heat the PCB area more, with some hotair or an oven. A lot of times I just solder onto SMD caps, but a via is stronger.Ages ago, I think I did this before, on some via in a 2 layer PCB, I never ever fixed that one, some day I'll try again, or just drill it out.

author: taste_tester
author_rank: Regular Contributor
timestamp: July 22, 2022, 07:28:55 am
content: Not going to lie, I had a very difficult time parsing what actually happened from your post.So what I will respond to is this point alone: "Or in general should u avoid soldering to via's in multilayer PCB's"in which case the answer is YES you should AVOID soldering to via's unless you are repairing PCB damage and it's the only choice.far too easy to damage other in between layers by adding too much heat to the area or even soak your solder into places it shouldn't be.I never do it unless it is an aforementioned scenario like a leaky cap ate at your PCB and your only choice is to locate a via and connect directly to it.It should be a last resort.

author: tooki
author_rank: Super Contributor
timestamp: July 23, 2022, 09:09:25 pm
content: I have a strong suspicion the OP is misusing the word “via” when they actually mean a plated through-hole.
Shorting A Capacitor - Page 1
Forum section: electronics / beginners

author: olsenn
author_rank: Frequent Contributor
timestamp: February 10, 2013, 11:38:31 pm
content: If a capacitor (let's say 1uF) is shorted, does the capacitance stay the same since caps in parallel add together (like resistors in series)? In other words, does that circuit look like a 1uF capacitor in parallel with a 0uF capacitor resultant in 1uF between those two nodes?

author: fcb
author_rank: Super Contributor
timestamp: February 11, 2013, 12:01:24 am
content: I literally have no idea what you mean.

author: c4757p
author_rank: Super Contributor
timestamp: February 11, 2013, 12:04:36 am
content: A short circuit isnotequivalent to a 0uF capacitor, that's an open circuit. If a short circuit is equivalent to any sort of capacitance at all it would be infinite, because you can keep feeding it more and more current and it never charges up.

author: smackaay
author_rank: Regular Contributor
timestamp: February 11, 2013, 12:26:30 am
content: It would be like an infinite capacitor with infinite leakage.

author: ddavidebor
author_rank: Super Contributor
timestamp: February 20, 2013, 10:02:04 pm
content: Shorted caps are no caps anymore, they're... Shorts!

author: c4757p
author_rank: Super Contributor
timestamp: February 20, 2013, 10:22:44 pm
content: Yep. A short circuit across an entire component - any component - completely removes it from the circuit. A short circuit by definition has the same voltage everywhere, so there can be no potential difference for the component to respond to. (Obviously arealshort circuit is actually a very, very small resistance and inductance, but for practical purposes it doesn't matter.)
Shorting AC Mains - Page 1
Forum section: electronics / beginners

author: Aodhan145
author_rank: Frequent Contributor
timestamp: March 08, 2015, 11:44:14 pm
content: Hi,I had built a Zero Crossing Detector and I was wandering why the DC voltage was lower than usual in the circuit it used to be like 10V and now it was like 4-5V. Then I started probing around to check what was wrong and when I was probing the mains the two probes arched across and then all my houses electricity went out and I had to reset the trip. what I don't understand is the probes where at least 2 cm away from each other. Is arching common at this distance and how do I prevent it?Thanks in advance

author: xrunner
author_rank: Super Contributor
timestamp: March 08, 2015, 11:51:21 pm
content: Dayum dude - be careful! Were you probing with a scope probe? If so, did you ground the hot side of the AC with the scope ground? 120 VAC should not arc across 2 cm.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: March 08, 2015, 11:56:55 pm
content: My scope was on Isolated DC Side. I was probing with the multimeter. I just went full retard.
shorting HP 6253A power supply - Page 1
Forum section: electronics / beginners

author: TX5Z
author_rank: Newbie
timestamp: January 13, 2025, 04:32:12 pm
content: Howdy,Is there a 'proper' way to short output terminals? This from the HP 6253 manual:3-7 CONSTANT VOLTAGE3-8 To select a constant voltage output, proceedas follows:a. Turn-on power supply and adjust VOLTAGEcontrols for desired output voltage (output terminalsopen).b.Short output terminals and adjust CURRENT controls for maximum outputcment allowable(current limit), as determined by load conditions.If a load change causes the cment limit to be exceeded, the power supply will automatically cross-'wer to constant cment output at the preset currentlimit and the output voltage wlll drop propartionately. In setttng the current limit, allowance must bemade for high peak current which can cause unwanted cross-ovet. (Refer to Paragraph 3-46.)THANK YOU for your time!

author: TimFox
author_rank: Super Contributor
timestamp: January 13, 2025, 04:51:08 pm
content: If you know the value you need for current limit, then just short the output terminals with a banana lead or whatever's convenient to adjust the current limit per their instructions.If you don't know, but have a working load that you want to power, just set the voltage, connect the load, and turn up the current limit until you are back to the correct voltage.Note that you may not be able to set the voltage (even with an open circuit) with the current limit pot fully counter-clockwise.

author: TX5Z
author_rank: Newbie
timestamp: January 13, 2025, 05:08:26 pm
content: Much clearer now. Thanks!

author: CaptDon
author_rank: Super Contributor
timestamp: January 13, 2025, 05:46:31 pm
content: What is cmet or is that a typo?

author: TX5Z
author_rank: Newbie
timestamp: January 13, 2025, 07:43:57 pm
content: Howdy,Should be 'current'.I have no idea why the copy and paste did not paste correctly - unless it had something to do with the original being a PDF. (I see there are some squares in the text as well.)
Shorting pot pins when used as variable resistor - Page 1
Forum section: electronics / beginners

author: fubar.gr
author_rank: Unknown
timestamp: June 12, 2015, 04:37:18 pm
content: I've noticed that it is customary to short one pin to the middle one when using a pot as variable resistor.Is there some reason for that? Wouldn't be simpler if one pin was left floating?

author: Halvmand
author_rank: Regular Contributor
timestamp: June 12, 2015, 05:13:22 pm
content: Usually it is because it avoids open circuit when the wiper is sliding.

author: fubar.gr
author_rank: Unknown
timestamp: June 12, 2015, 05:20:23 pm
content: Quote from: Halvmand on June 12, 2015, 05:13:22 pmThanks, I wouldn't have though of that

author: Kjelt
author_rank: Super Contributor
timestamp: June 12, 2015, 05:24:09 pm
content: What you actually get when you do not connect one pin is two resistors from which one is floating.I can imagine that in some (HF?) circuits the floating resistor could become an antenna picking up noise.
Shorting Power Supply immediately after disconnecting bad? - Page 1
Forum section: electronics / beginners

author: skillz21
author_rank: Frequent Contributor
timestamp: January 19, 2019, 12:58:04 pm
content: I have a DC-DC boost converter board. When I have it at higher voltages and connect a heavy load (or accidentally short the output) sparks appear. If I disconnect the input power, then immediately short the output, the voltage from the capacitors still produces some sparks. Will me shorting the output straight after disconnecting the input, damage the board in any way?

author: mvs
author_rank: Frequent Contributor
timestamp: January 19, 2019, 01:40:36 pm
content: Boost topology does not provide any current limiting in case of short circuit at the output. If high current capable source is connected to the input you may damage diode, pcb traces or inductor. If input is disconnected, it is not that wild, caps may withstand such abuse many times. But there is no reason to do it intentionally. If you do need to discharge capacitors use some load (resistor, light bulb, etc.) with higher resistance then 0 Ohm.

author: rstofer
author_rank: Super Contributor
timestamp: January 19, 2019, 04:19:08 pm
content: Remember, the current is related to the change in voltage per unit time or I = C dv/dt. dv/dt is the change in voltage per unit time and C is the capacitance in Farads. Suppose you discharge a 100 ufd capacitor from 12V to 0V in 1 microsecond. Then dv/dt = 12/0.000001 or 12,000,000 volts per second. Multiply by 0.0001 Farads and you get I = 1200 Amps.Shorting capacitors is a really bad idea. A 100 ufd is a pretty small capacitor, how about 3500 ufd? That would give you 35 times as much current or 42,000 Amps. That should light things up! Briefly...There may be some internal resistance that tends to limit the current and it might be worth considering but, basically, those arcs and sparks are a bad thing.
shotcicut protection - Page 1
Forum section: electronics / beginners

author: 07Pepa
author_rank: Newbie
timestamp: July 10, 2015, 03:26:10 pm
content: Hi I am preaty much biginer. there is my case: i want filter the output of diode brige with capacitor. i know right walue for that but, i want to protect it from cap failtiure i read somewhere i can do it by just resistor in serie. but i need a value ( it will be +/- 12V dc at maximaly 50W (and i can proof the walue are corect i am using cheep chinese ac to ac trafo wich is hopefuly strong enougt to power 12v dc 30W led strip.THX for help

author: PSR B1257
author_rank: Frequent Contributor
timestamp: July 10, 2015, 03:42:00 pm
content: There is noting to protect for anycap-failure.Your LED-strip by the way, will work fine also without a filter cap.

author: 07Pepa
author_rank: Newbie
timestamp: July 10, 2015, 04:44:23 pm
content: PSR B1257 you are right but just knd of. I can see a 50hz flicker (in peripheral viev)

author: Zero999
author_rank: Super Contributor
timestamp: July 10, 2015, 04:49:51 pm
content: A fuse will provide short circuit protection but it needs to be slow blow type, in order to avoid it blowing when the circuit is turned on and the capacitor charges.

author: PSR B1257
author_rank: Frequent Contributor
timestamp: July 10, 2015, 06:20:21 pm
content: QuoteNo you don't, sinceQuoteI just tried it myself and can't see any flicker whatsoever.But if I just connect a single rectifying diode the flicker is pretty terrible.Therefore either you're diode bridge is damaged or you have hooked it up wrong.P.S.: A filter cap is in this case rather problematic since itraisesthe voltage by the factor of sqrt(2), like every bridge rectifier with an filter cap. The LED-stripe is designed for a nominal voltage of 12V - about 15V might be too high for the LED-stripe (long term seen).The so called Average rectified value of a sinusoidal voltage however is 0.9URMS. Meaning it is no problem to hook up 12VAC bridge rectified directly to a 12VDC load.

author: IanB
author_rank: Super Contributor
timestamp: July 10, 2015, 06:24:57 pm
content: It is certainly possible to see a 100 Hz flicker from a full wave rectifier in your peripheral vision if you have good eyesight. Why the disbelief?

author: PSR B1257
author_rank: Frequent Contributor
timestamp: July 10, 2015, 06:43:18 pm
content: QuoteJust because I can't see any sign of flicker (independent of viewing angle and distance) - that's allI only can see it with an oscilloscope (who would have thought) and through a camera...