hybridfree/eevblog-posts huggingface dataset:
USB-Type C power supply question - Page 1
Forum section: electronics / beginners

author: Asparagus
author_rank: Newbie
timestamp: May 19, 2016, 01:52:56 am
content: We are trying to build a custom USB -Type C power supply. The power supply will use USB PD 3.1 specs which means it should be able to work with any device that use the same specs like Google Chromebook, mac book 2016 model, nexus phone 2016 model and many more in the future.I need to program/reprogram a PD controller chip so that certain PDO's are hidden from the public. During the power delivery negotiation the sink will ask the source what are the available PDO's(power delivery options) in which case the source should respond back with 5, 12, 15 and 20 volts @1,2,3 amps.Would it be possible to send the source a vendor defined message which will open up more options?. For Instance, if the source sees a vendor defined message with id "XYZ12345" it should provide 2 additional PDO's 20volts@4amps, 20volts@5 amps. This logic will have to be programmed into the PD chip on the source side.According to my research I can use the chip UPD1001 manufactured by microchip. The manufacturer says that it is configurable but I am not sure if it means that it is reprogrammable.Please let me know if this is possible?
USB UART with protection - Page 1
Forum section: electronics / beginners

author: Aashram
author_rank: Newbie
timestamp: August 30, 2017, 02:12:55 pm
content: HiI am trying to make a circuit for USB to UART. For that I am using:FTDI230X:http://www.mouser.de/ProductDetail/FTDI/FT230XS-R/?qs=sGAEpiMZZMvVkErl6zY%2bqR%2b6A%2bu/1HB5WE TVS Diode Array 824011:http://www.mouser.de/ProductDetail/...=sGAEpiMZZMsgNhPy3wz0s7JC25wFgpK3tUoJ3YHBnr0=Common Mode Chokes / Filters WE:http://www.mouser.de/ProductDetail/...qnvsilMhY5xdooAk%2bM7YdNaABXylUlITcfstZkF/w==And Ferrite for VBUS:http://www.mouser.de/ProductDetail/Wurth-Electronics/742792641/?qs=5twSNpOB8IBOTWTDxxe6GA==I have attached the rough schematic.Am I doing right?Where should I connect VBUS ( to VCC or VCCIO or 3V3OUT)?The other pins in FTDI I have marked as NC, Is this OK?Do I need to add capacitor also in this design?Thank you all.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 30, 2017, 02:25:18 pm
content: You will need more than 100nF capacitance.You won't need a common mode choke for a bus-powered device.http://jeroen3.nl/isoftdi

author: Aashram
author_rank: Newbie
timestamp: August 30, 2017, 02:54:49 pm
content: Thanks JeroenI came across with the design you posted. I understand we dont have to use common mode choke but I have to use it for our company standard purpopse. The schematic which I posted if I want to use same component then what can be the configuration should I follow. Because thre is too much information is available and so I am little confused.And how do I connect VBUS to FTDI?And how does the VCCIO and 3V3OUT of FDI is connected?I have attached the new schematic,I hope this will give you my side.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: August 30, 2017, 03:14:09 pm
content: Have you read the datasheet?http://www.mouser.com/ds/2/163/DS_FT230X-5395.pdfFig 6.1 shows an example schematic for a bus powered configuration. VCCIO needs to be tied to whatever your I/O voltage is. 3V3OUT is an optional output from the FTDI chip that you can use or not, up to you.
USB VID - Page 1
Forum section: electronics / beginners

author: abdullahseba
author_rank: Frequent Contributor
timestamp: February 13, 2016, 03:54:26 pm
content: HiDo you need a VID for a HID USB controlled circuit (such as a 3D printer)?The HID sorts out the Microsoft driver fee but I wasn't sure about the VID.Thanks in advancePS: POXY Microsoft and USB forum FEEEES

author: Jeroen3
author_rank: Super Contributor
timestamp: February 13, 2016, 04:10:42 pm
content: This question has been asked, and answered, many times before.https://www.eevblog.com/forum/projects/usb-vidpid/msg445814/#msg445814https://www.eevblog.com/forum/projects/usb-vendor-product-ids/msg403471/#msg403471Probably many more.Also, you obtain a VID fromUSB.org. Not from Microsoft. You obtain asignaturefrom Microsoft to sign your driver with, that is something completely different.Notice that is it mandatory to sign drivers since Windows 8 and higher (else they won't install), unless you put the OS in a special (unsafe) mode.
usb without the 5v line - Page 1
Forum section: electronics / beginners

author: FrankT
author_rank: Regular Contributor
timestamp: August 11, 2013, 12:10:52 am
content: I'm adding a spinning part to my robot. I'm planning to use a small slip ring (like thishttp://www.adafruit.com/products/1196) to transfer signals and power.However, I'm running out of wires. I need to double up some of the power wires to handle the current requirements.I already pass 5v through the slip ring and I was wondering, can I use just the D+/D- lines coming from a usb hub, and then use the existing 5v/gnd (instead of using the USB 5v/gnd lines) ?The usb signal is coming from a 5v powered usb hub. Everything is powered from the same battery - 3 cell lipo (12v for motors, and I have a 5v dc-dc converter).I'm wondering if there will be any monitoring of the 5v output at the usb hub that may stop this from working. I know there are over current checks.Thanks,Frank

author: Unknown
author_rank: Unknown
timestamp: August 11, 2013, 12:32:11 am
content: The only problem I see is that the device should tri-state the data lines if the host is powered down, this is hard to detect without monitoring the 5V line. But if it's part of the same system and you can guarantee proper sequencing, then I think it should work fine. I'm not aware of any hosts checking power consumption.

author: SeanB
author_rank: Super Contributor
timestamp: August 11, 2013, 05:43:49 am
content: A lot of self powered USB devices just use the USB power as a power on indicator. Can you not just arrange a LED ring around the rotor so it shines on a phototransistor to signal power status? That way it just will take a retriggerable monostable to give a USB powered signal.

author: Smokey
author_rank: Super Contributor
timestamp: August 11, 2013, 06:30:07 am
content: I'm pretty sure you can do USB over Wifi in linux. Could you just push the power over the slip ring and do all the data over RF? The answer is probably no due to bandwidth, but worth thinking about.
usbasp stopped working - Page 1
Forum section: electronics / beginners

author: Hugo Balls
author_rank: Newbie
timestamp: April 06, 2016, 07:57:45 pm
content: Hi nerds.About a month ago i built my own little avr usb programmerhttp://www.fischl.de/usbasp/.Today while I was debugging a simple project with Atmega8, 16x2 LCD and some I2C chips and out of nowherethe software i was using to interface usbasp(Bascom avr) tells me that, it can't find it(the programmer itself). Avrdude - same.So I checked everything, reinstalled drivers and nothing. I can get it working for about 5 seconds which can be achievedby unplugging and plugging it back in(sometimes multiple times) then it stops working again, green led is always on, so its not all lost.Thoughts? I'm thinking its a problem on the pc side(usb is fine though).Specs:Windows 10ATmega8-16PU inside usbasp

author: michaeliv
author_rank: Frequent Contributor
timestamp: April 06, 2016, 10:29:14 pm
content: Do you have another usbasp to test to see if that is working ?I would guess that the built USBAsp stops functioning, try to see if the clock is still oscillating.Also, after the 5 seconds, when it doesn't work any more, try re-flashing the firmware and see if that works.

author: sleemanj
author_rank: Super Contributor
timestamp: April 06, 2016, 10:45:01 pm
content: Check the pull-up resistor on the RESET pin of the ATmega... if you don't have a pull-up on RESET add a pull-up on RESET.If it's the OS shutting down the connection you should have a log entry with more details (on Linux you'd look in /var/log/syslog ; in Windows, I dunno, I guess it's Event Viewer or something; in Mac, I dunno maybe it has /var/log/syslog as well).Otherwise check voltage on the USB port to see if it's dropping too low (seems unlikely to drop so low that an AVR will shut down), and maybe more importantly, check for shorts on your USBAsp, if you have a "Charger Doctor" type device slap it in series and that will tell you if it is drawing abnormally high current or the voltage is abnormally low.

author: Hugo Balls
author_rank: Newbie
timestamp: April 07, 2016, 08:20:26 am
content: Pull-up on reset is there, voltages are fine, no shorts, green led is on. The thing is that windows seems to properly detect it but software can't.Unfortunately I don't have another programmer to reflash this one right now and no oscilloscope.Here is some kind of log
usbasp to suppose voltage for experiments? - Page 1
Forum section: electronics / beginners

author: casper.bang
author_rank: Frequent Contributor
timestamp: April 06, 2015, 12:07:00 pm
content: Unlike high quality programmers like the AVRISP mkII programmer, on cheap Chinese USBASP clones*, I guess there are NO protection what-so-ever against shorts between the 5V power rail and group - so using it to do anything else than power programming (say run experiments on a breadboard) is thus a bad idea as it puts the USB port in jeopardy.What would the easiest way be to add some protection? I'd like to make a programming adaptor (10 pin header) which can also power the board during breadboarding. Is a small linear 3.3V regulator the way to go then?*http://www.ebay.co.uk/itm/10-Pin-Cable-USBASP-USBISP-AVR-Programmer-Adapter-USB-ATMEGA8-ATMEGA128-Arduino-/381216028308?pt=LH_DefaultDomain_0&hash=item58c23ef694

author: Psi
author_rank: Super Contributor
timestamp: April 06, 2015, 12:16:37 pm
content: Shorting the 5V USB rail to GND isn't an issue. The USB standard requires protection from shorts be incorporated into the USB port.However, shorting USB power to a higher voltage might be a different story, never tried it.

author: JohnnyBerg
author_rank: Frequent Contributor
timestamp: April 06, 2015, 12:40:00 pm
content: Isn't there a 3.3V regulator on the programmer?The listing says it can deliver 3.3V

author: casper.bang
author_rank: Frequent Contributor
timestamp: April 06, 2015, 03:39:16 pm
content: Quote from: JohnnyBerg on April 06, 2015, 12:40:00 pmIndeed, on the rear side there's an AMS1117 [http://www.advanced-monolithic.com/pdf/ds1117.pdf] which I guess means I am safe.

author: casper.bang
author_rank: Frequent Contributor
timestamp: April 06, 2015, 03:40:57 pm
content: Quote from: Psi on April 06, 2015, 12:16:37 pmSo what you are saying is, attaching the programmer directly to a breadboard should be safe as long as it's the only power being used? I do wonder then why you never really see USB programmers+prototyping boards in one.

author: Grapsus
author_rank: Regular Contributor
timestamp: April 06, 2015, 03:49:37 pm
content: For low-speed (1.5 Mbps, which is the case for USBasp) and full-speed (12 MBps) you have relatively cheap isolators :http://www.amazon.com/HifimeDIY-Isolator-ADUM4160-signal-isolation/dp/B00F4SCCR2https://www.olimex.com/Products/USB-Modules/USB-ISO/They have full galvanic or optic isolation for both power and data lines so it should protect your computer in case something goes wrong.
use a CC power supply to charge lithium cell? - Page 1
Forum section: electronics / beginners

author: ice595
author_rank: Regular Contributor
timestamp: April 10, 2014, 03:14:11 pm
content: From what I've heard, using a voltage source to charge lithium cells may result in a lot of smoke and flamesBut how about using a bench supply with CC mode to charge lithium cells?Set the current limit to safe level (i.e 100mA) then set the open circuit voltage to 4.2vIn theory, when the lithium cell voltage reaches 4.2v, it will match the power supply's open circuit voltage and stops charging.but how well does that work? has anyone attempted this before?

author: eKretz
author_rank: Frequent Contributor
timestamp: April 10, 2014, 03:39:45 pm
content: Yup, do it all the time. Works great!

author: rolycat
author_rank: Super Contributor
timestamp: April 10, 2014, 04:22:09 pm
content: I've done this as well, but charging does not stop when the voltage reaches 4.2 volts, and if you disconnect the supply at this point the cell will only be partly charged.To get a full charge, leave the cell charging at 4.2V until the current reaches about 10% of the initial charge rate. It's dangerous to leave lithium cells 'trickle charging', so you need to calculate the time at which this will occur and set an alarm so you don't leave it too long.Unless it's an infrequent operation, you are much better off with a proper charger.

author: eKretz
author_rank: Frequent Contributor
timestamp: April 10, 2014, 05:44:31 pm
content: Right, I typically charge 4 cells at a time in parallel and cut off charging when the amperage drops to 100-200mA.

author: ice595
author_rank: Regular Contributor
timestamp: April 10, 2014, 06:18:52 pm
content: is there a simple circuit to cut off charging then the current reaches a set amount?my guess would be using a op-amp comparator circuit to do this.

author: Len
author_rank: Frequent Contributor
timestamp: April 10, 2014, 06:55:30 pm
content: Quote from: ice595 on April 10, 2014, 06:18:52 pmHow about one of the simple Li-ion charge controllers? This one is cheap and looks easy to use (haven't tried it myself):http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en024903

author: Witention
author_rank: Contributor
timestamp: April 29, 2014, 06:08:32 pm
content: Check the cell data sheet to see if any voltage or current levels could damage or degrade the cell performance. Use the power supply's over voltage or over current protection features to ensure the power supply output shuts off if any unwanted voltage or current levels are reached.

author: AndreaEl
author_rank: Contributor
timestamp: April 29, 2014, 09:07:51 pm
content: If it can help there arehttp://batteryuniversity.com/learn/with a lot of information about battery.in particular: Charging Lithium-ion:http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
use a npn for q1 - Page 1
Forum section: electronics / beginners

author: p.larner
author_rank: Frequent Contributor
timestamp: March 07, 2024, 11:58:07 pm
content: Hi what do i need to alter on this schematic to use a npn for q1,thanks.

author: David Hess
author_rank: Super Contributor
timestamp: March 08, 2024, 01:31:36 am
content: Quote from: p.larner on March 07, 2024, 11:58:07 pmConnect pin 11 to pin 12 and use the NPN emitter at pin 10 to drive the base of Q2 directly. If the current or power requirement is too high, then convert Q2 to a Darlington configuration with a BD711, or the NPN power transistor of your choice.

author: Xena E
author_rank: Frequent Contributor
timestamp: March 08, 2024, 01:47:11 am
content: To replace Q1 with an npn transistor connect the 723 pin 11 and 12 together with the NPN Q1 collector, the base to pin 10 and the emitter to the pass transistor base.This configuration will have a higher dropout voltage.The 723 can drive 150mA without Q1.If this is adequate, do as David says.
Use a step up transformer the other way around - Page 1
Forum section: electronics / beginners

author: robsims
author_rank: Frequent Contributor
timestamp: February 24, 2023, 03:41:39 am
content: Hi,Can i use a 110v to 220v step-up transformer the other way around. Convert 220v to 110v?

author: BillyO
author_rank: Super Contributor
timestamp: February 24, 2023, 03:52:36 am
content: Yes, this should work. Just be careful.

author: bdunham7
author_rank: Super Contributor
timestamp: February 24, 2023, 04:03:07 am
content: Maybe. Many transformers like that don't use exact 1:2 windings, they'll do something like 1:2.2 to account for voltage drop under load. They might aim to be 10% high at no-load and 10% low at full load. If you reverse that, you will be about 9% low at no load and ~19% low at full load.

author: robsims
author_rank: Frequent Contributor
timestamp: February 24, 2023, 08:45:58 am
content: Quote from: BillyO on February 24, 2023, 03:52:36 amOk thanks

author: Kleinstein
author_rank: Super Contributor
timestamp: February 24, 2023, 09:06:10 am
content: Quote from: bdunham7 on February 24, 2023, 04:03:07 amHow much the turns ratio is different from the nominal voltage ratio depends transformer type and size. Small transformers (e.g. < 10 VA) have a relatively large voltage drop at nominal load and large ones get better. So the 10% number is more like an example number maybe right for some 100 VA. Especially transformers smaller than some 3 VA have a rather poor efficiency and don't follow the simple picture and turns ratios anymore.

author: Psi
author_rank: Super Contributor
timestamp: February 24, 2023, 10:42:38 am
content: Some voltage mismatch is usually not a problem.Considering there are countries that have 220V, 230V or 240V.And there is some vdrop even with mains. Those who have the step down transformer right outside their house in a 240V country might actually be getting 250V because the output of the transformer was spec'ed a bit higher to allow it to service people further away without dropping too low. I remember someone long ago who lived at a place like that. They were always complaining that incandescent lights didn't last very long.
Use AC SSR for DC? - Page 1
Forum section: electronics / beginners

author: iXod
author_rank: Frequent Contributor
timestamp: January 15, 2021, 07:38:51 am
content: Can a solid-state relay specified for an AC load voltage conduct a low (12) DC voltage instead?The SSR input trigger voltage is specified as 4-32 vdc and load as 24-240 vac.Thanks.

author: ledtester
author_rank: Super Contributor
timestamp: January 15, 2021, 07:49:42 am
content: Maybe. This page says it depends on what the switching element is:https://www.allaboutcircuits.com/technical-articles/basics-of-ssr-solid-state-relay-the-switching-device/Apparently MOS-based SSR's can be used to drive either AC or DC loads.

author: Zero999
author_rank: Super Contributor
timestamp: January 15, 2021, 09:14:43 am
content: Quote from: iXod on January 15, 2021, 07:38:51 amThat's not enough information to go on. As mentioned above, it will only work if it has a MOSFET output stage. My hunch is that it's probably a TRIAC, as it's only speicified to work on AC. This means if it's used with DC, it will act as a one shot device. In other words, once triggered, it will turn on and stay on, until the DC power is interrupted.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 17, 2021, 07:02:14 pm
content: Turning off TRIAC in a DC circuit is fairly easy. To do this, it is necessary to briefly bypass. It is best to do this with a low-power TRIAC + capacitor circuit. This circuit will briefly take over the flowing current while the capacitor is charged and the TRIAC closes. When the capacitor is charged, the auxiliary TRIAC will also close. An auxiliary TRIAC can be a triac optocoupler.
use Arduino's on chip ADC to measure current? - Page 1
Forum section: electronics / beginners

author: ice595
author_rank: Regular Contributor
timestamp: May 30, 2014, 02:47:44 pm
content: I want to use an Arduino to control 3 high power LED chips. Each LED chip can take 10 watts.im using a mosfet switching circuit with PWM to drive those LEDs.From what I have heard, high power LED chips require a current source to driven properly.Is there a easy way to sense DC current with the ADCs on the Arduino.I wouldn't think its as easy as using a current sense resistor in series with the LED and use the ADC to measure voltage across the resistor then use ohm's law. Since the LEDs are driven by PWM rather than a smooth analog voltage.Any ideas on making this happen?

author: idpromnut
author_rank: Unknown
timestamp: May 30, 2014, 03:39:52 pm
content: I'm a bit of a noob myself, but I would think you would build a CC driver, and then PWM the driver, thus removing the need to sense the current (since it would be guaranteed to be constant anyways). After that, I don't know why you would want to measure the current, except to calculate actual power usage or something of that nature?

author: theatrus
author_rank: Frequent Contributor
timestamp: May 30, 2014, 04:34:37 pm
content: Is your current design just a PWM to a FET in order to turn on and off the LED? What, if anything, are you using for current control?For something in the multi-watt range, you probably want to use a standard buck (or boost) topology, which means you are controlling your PWM circuit based on current through the string and the current in the inductor. While a linear CC driver is possible, your efficiency is pretty terrible unless you can very closely match the input voltage to the needed LED voltage (+offset).You can save yourself a lot of heartache (and broken LEDs) if you use an existing buck controller, which are quite cheap these days. An NCP3066 is a cheap option, and has a built-in PWM control input. Depending on how the LED chip is made (series, parallel), the LM3404 (HV) can also drive high voltage 1A series strings.
Use cases for Dual N-Channel MOSFET with Common Drain - Page 1
Forum section: electronics / beginners

author: girishv
author_rank: Regular Contributor
timestamp: August 18, 2020, 05:36:36 am
content: I was sourcing logic level N-Channel MOSFET for a project. I ended up buying a reel of Dual N-Channel MOSFET's (IRL6297SDPbF) with common drain as price was lower than any single N-Channel MOSFET of similar specification.The specifications of IRL6297SDPbF are VDSS 20V / VGS 12V± / RDS 5.3mΩ @ 2.5V / RDS 3.8mΩ @ 4.5V / Is 25AI don't know what to do with the excess quantity.Please point me to use cases of common drain dual N-Channel MOSFET's

author: chris_leyson
author_rank: Super Contributor
timestamp: August 18, 2020, 05:39:05 am
content: Analog switch perhaps.

author: Circlotron
author_rank: Super Contributor
timestamp: August 18, 2020, 06:07:14 am
content: Synchronous rectifier for forward mode SMPS that normally uses dual schottky with common cathode.

author: TimNJ
author_rank: Super Contributor
timestamp: August 18, 2020, 06:23:42 am
content: As Blueskull said, but more generally, somewhere where you need to switch a power source on or off, but cannot accept back-flow through the body diode.

author: girishv
author_rank: Regular Contributor
timestamp: August 18, 2020, 06:48:17 am
content: Quote from: chris_leyson on August 18, 2020, 05:39:05 amCould you point me to an example?

author: girishv
author_rank: Regular Contributor
timestamp: August 18, 2020, 06:51:42 am
content: Quote from: Circlotron on August 18, 2020, 06:07:14 amThanks. I will explore. If you have some example schematics in mind, please share.

author: girishv
author_rank: Regular Contributor
timestamp: August 18, 2020, 07:03:36 am
content: I found a bi-directional power switch example in one of the tech notes of TIhttps://www.ti.com/lit/an/slva948/slva948.pdf?ts=1597733747278&ref_url=https%253A%252F%252Fwww.google.com%252F

author: Zero999
author_rank: Super Contributor
timestamp: August 18, 2020, 08:26:15 am
content: You could use it as a single MOSFET, by connecting both in parallel.

author: fcb
author_rank: Super Contributor
timestamp: August 18, 2020, 08:38:31 am
content: girishv,That's a really great application note (ti.com SLVA948), thanks for pointing it out.
Use Fluke probes on Brymen multimeter - Page 1
Forum section: electronics / beginners

author: jancelot
author_rank: Regular Contributor
timestamp: June 07, 2015, 07:11:30 pm
content: Hi, wondering if can buy the Fluke TL175 probes or other variant and use them in the Brymen BM869s or the BM257s. Any ideas?

author: GreyWoolfe
author_rank: Unknown
timestamp: June 07, 2015, 07:16:12 pm
content: I don't see why that would be a problem, I use Brymen leads on my Fluke 27FM.

author: jancelot
author_rank: Regular Contributor
timestamp: June 07, 2015, 07:28:03 pm
content: Thanks, good to know

author: cs.dk
author_rank: Unknown
timestamp: June 07, 2015, 08:37:46 pm
content: I use Fluke probes on my BM869 and BM257 (No S-version though), no worries. They are standard 4 mm shrouded banana plugs, so every "standard" probe will fit.

author: kingofkya
author_rank: Regular Contributor
timestamp: June 09, 2015, 05:58:04 am
content: you want these instead trust me:)http://www.probemaster.com/index.php?cPath=2http://www.amazon.com/8000-Series-Test-Lead-Kit/dp/B000TLXGE2/ref=sr_1_1?ie=UTF8&qid=1433829429&sr=8-1&keywords=probe+master&pebp=1433829443020&perid=1T6ACYG1ZHPJCACW8HRC

author: nanofrog
author_rank: Super Contributor
timestamp: June 09, 2015, 06:26:00 am
content: Quote from: kingofkya on June 09, 2015, 05:58:04 am+1 for Probemaster.FWIW, the sets offer better value than Fluke/Pomona IME, and it's usually cheaper to buy direct.
Use for ground coupling on scope? - Page 1
Forum section: electronics / beginners

author: Phaedrus
author_rank: Frequent Contributor
timestamp: May 30, 2014, 09:14:28 pm
content: So I use my scope's AC and DC coupling modes quite a bit for all the usual tasks, but I've never found a use for GND coupling. Maybe once I get my 2465a in good shape it will be useful? But on my DSO I can't find any use in it. Is there something I'm missing? Or is this feature only included out of tradition?

author: w2aew
author_rank: Super Contributor
timestamp: May 30, 2014, 10:06:55 pm
content: Quote from: Phaedrus on May 30, 2014, 09:14:28 pmIt is useful to "pre-charge" the AC coupling cap with the DC content of the signal - at least that's how many of the old Tek scopes worked. Then, when you switched to AC coupling, the signal would be steady on-screen rather than "settle" from above or below the screen at the blocking cap gets charged. I'd have to check to see if the new scopes work this way too...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 30, 2014, 10:37:38 pm
content: Not really "useful"... it's kind of intentionally anti-useful, really. That's not to say useless; much like matter and antimatter, neither one is altogether null.On analog scopes, the main purpose is to zero the trace to quickly see where it's referenced to, or if it needs adjustment, to give a flat line so you can line it up with the graticule.On digital scopes, it's more either to clear an extra waveform without shutting off the channel, or to sanity-check the converter (a crapped out converter might read the ~mV noise on GND and convert it to nonsense, rather than a correct ~zero reading).Tim
Use iRig 2 with windows based signal generator and oscilloscope software? - Page 1
Forum section: electronics / beginners

author: YurkshireLad
author_rank: Frequent Contributor
timestamp: December 28, 2021, 07:12:59 pm
content: I found my iRig 2 (https://www.ikmultimedia.com/products/irig2/) that I thought I had sold. Could I use it to run signal generator and oscilloscope software on Windows? I installed audacity, which should let me perform a frequency analysis. I want to play around with audio filters and it'll be interesting to see their effect, not just hear how they change the audio signal.I realize there's always a chance I could damage my laptop if I can use it in these ways, but that's always an excuse to buy a newer one, right?To clarify I just need a simple sine wave generator. Also, I have a tiny DSO so the oscilloscope software would be more for learning the more complicated aspects of oscilloscopes than anything else. Not necessarily using it as my main scope.
use low resistance wire as potentiometer in ADC  - Page 1
Forum section: electronics / beginners

author: topcat
author_rank: Contributor
timestamp: May 28, 2018, 07:15:54 am
content: Hello,I am building a little application where I want to seance to position of a wiper on a long wire (approx 1m).It a copper wire so resistance is very low.Ideally I could just connect one end to GND and the other to VCC and directly input the moving seance arm into the ADC input.But obviously current flow will be too high in my wire.Is there any simple approach for this?Adding a current limiting resister changes the voltage gradient across my wire, and I really want to have good dynamic range maybe not the whole 10bits but close to 0-5vThanks Dag.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: May 28, 2018, 08:21:32 am
content: Well if you're going to summon spirits from the realm of the dead, I think silver is the appropriate metal to channel energy.

author: tszaboo
author_rank: Super Contributor
timestamp: May 28, 2018, 08:35:13 am
content: You could place the potentiometer in a bridge (with a series resitor), called wheatstone bridge, and then amplify the signal with an instrumentation amplifier. Or use an ADC with a PGA in it. Dont expect to solve this problem without adding components.

author: Brumby
author_rank: Unknown
timestamp: May 28, 2018, 08:39:32 am
content: My first thought drifts towards Nichrome - but I don't know if that will be a suitable Medium.

author: Gyro
author_rank: Super Contributor
timestamp: May 28, 2018, 08:42:43 am
content: Why does the wire need to be copper? It will have poor resistance to mechanical wear, which will degrade its linearity.Also Copper has a high temperature coefficient (it will get hot), so it won't be linear near where it is terminated (cooled) at the ends and probably at the wiper too if it has any thermal mass.

author: topcat
author_rank: Contributor
timestamp: May 30, 2018, 08:59:53 am
content: Thanks for the help.I am going to just start sensing as the undead were interfering with my measurements.Anyway I don't think Nichrome has high enough resistance for me, none that I could find to buy did anyway.So I think I do as NANDBlog suggested.

author: jeroen79
author_rank: Frequent Contributor
timestamp: May 30, 2018, 01:00:01 pm
content: What is the background of your question?What are you trying to accomplish?Does the wire have an existing function?And do you want to use it as a potentiometer for a secondary function?

author: JS
author_rank: Frequent Contributor
timestamp: May 30, 2018, 03:07:03 pm
content: You should probably use a 4W resistance metering system, but you will need to amplify the signal after the wire. 5V across 1m of cooper wire is never a good choice, if the wire is small enough to have reasonable current draw it will overheat. If it's thick enough current will be too high anyway for the wire, even if you can supply it and you can afford the energy loss.JS
Use of banana to BNC adapter on power supplies - Page 1
Forum section: electronics / beginners

author: petert
author_rank: Regular Contributor
timestamp: January 23, 2020, 02:49:44 am
content: Hi,Some power supplies don't have the right spacing to fit a banana plug pair to bnc adapter. I found alternatives that use cables, such that the spacing of the binding posts does not matter.To know how that would affect the result (rigidly shaped "box" adapter vs. flexible cable adapter): why would you need such an adapter in the first place? What kind of measurements would you want to do that required it?And what are the tradeoffs of the two kind of adapters above, or possibly other solutions, where you just use an oscilloscope probe directly?Are there other uses for such adapters, beyond using them on power supplies (e.g., to measure ripple current)?

author: hexreader
author_rank: Frequent Contributor
timestamp: January 23, 2020, 02:59:15 am
content: Most multimeters have standard spacing that suit BNC adapters. Convenient sometimes for voltage measurements, and probably the most obvious use.Those adapters are poorly suited to Power use, but can be used for low currents.Be aware that some (cheaper) BNC connectors give intermittent screen connection.

author: petert
author_rank: Regular Contributor
timestamp: June 10, 2020, 08:24:43 pm
content: Thanks, and why would use something like this:https://i.ebayimg.com/images/g/090AAOSw9yJbmgyQ/s-l500.jpgWhat's the point of connecting banana plugs to an oscilloscope instead of just using the scope probes, which will likely give better results?And why would you use this on a power supply, since it can't handle any large current with bnc/coax?https://i.ebayimg.com/images/g/KfsAAOSw1DtXGcKJ/s-l500.jpg

author: hexreader
author_rank: Frequent Contributor
timestamp: June 10, 2020, 08:44:46 pm
content: My random thoughts - worth what you paid for them (nothing)...QuoteSometimes banana leads are more convenient and good enough for low frequencies, such as measuring power supply ripple. Connecting a scope probe to recessed 4mm sockets might be tricky and unreliable. 4mm leads give solid, reliable connections (though the adaptor may make your setup less reliable).QuoteI would not use this adaptor for high currents or where reliability is important. I do use these for quick and dirty power supply connections at low currents, but I am occasionally disappointed when connection is intermittent.I use the cheap adaptors. Maybe the branded, high price adaptors are better? Not rich enough to have tried them.YMMV

author: petert
author_rank: Regular Contributor
timestamp: June 10, 2020, 08:56:20 pm
content: Thanks, your thoughts were definitely valuable, even if freeMeasuring power supply ripple makes a lot of sense.If anyone else can mention other applications, I'd be curious.
Use of big electrolytic capacitors in a DC/AC mains inverter  - Page 1
Forum section: electronics / beginners

author: abhishekkumar1902
author_rank: Regular Contributor
timestamp: June 20, 2017, 12:27:46 pm
content: I was browsing some low freq transformer based DC/AC mains inverter circuits (like 12v DC to 220v AC) online and found a couple of designs having these big chunky electrolytic capacitors.This may sound a foolish questions but any idea exactly on which rails they use these big caps and why is it needed when the inverter is already using a DC source to drive your inverter?I am sure they're not used in any low pass filter circuit as the value of cap is pretty big is what I saw.

author: strawberry
author_rank: Super Contributor
timestamp: June 20, 2017, 04:18:21 pm
content: It is low impedance power source

author: abhishekkumar1902
author_rank: Regular Contributor
timestamp: June 20, 2017, 04:31:02 pm
content: How does it helps?

author: MagicSmoker
author_rank: Super Contributor
timestamp: June 20, 2017, 04:56:21 pm
content: An inverter draws pulses of current from its supply; the capacitors supply those pulses, minimizing the effect of any stray inductance in the supply wiring.
Use of chassis/earth for interference suppression? Please help me to understand - Page 1
Forum section: electronics / beginners

author: Zucca
author_rank: Unknown
timestamp: April 08, 2014, 03:35:48 am
content: After a unsuccessful quick search here for "earth interferece", I decided to put this post together.I was just looking at the Keithley 220 schematics (see at the end of this manual below)http://www.tunl.duke.edu/documents/public/electronics/Keithley/Keithley_220_Current_Source_Manual.pdfand I am trying to learn something new.I am confused to see how they used the earth/chassis potential.For example A page 57:and example B page 60:So clearly it is for high freq jazz, but why in one case I have a resistor and in the other one not?Moreover why in example A filtering just the digital ground? Why not also the analog one? It is maybe because the interference is generated by the quick digital circuits inside by the device and not coming from outside?And in example B, may be since there is a IEEE digital bus coming from a PC I need to take care about the ground loop with that cap. Am I correct?Thanks a lot in advance.

author: Rudane
author_rank: Regular Contributor
timestamp: April 08, 2014, 06:21:24 pm
content: This first one looks like a filter connected to that input bridge, probably to shunt any unwanted noise. The second one looks like isolation of grounds. The cap stops noise from crossing from one ground to the other. These are my "educated" guesses.

author: linux-works
author_rank: Super Contributor
timestamp: April 08, 2014, 07:06:07 pm
content: first one looks more like a ground loop isolator. at dc, it blocks but at ac, its more like a short to ground. you don't get any dc shorts but only have an effective short to ground for higher freq stuff. therefore, no ground loop and definitely not at 60hz.same concept on the other one. high freq shunt to ground; blocked at dc (ie, dc connect is to local ground, not earth ground).

author: Zucca
author_rank: Unknown
timestamp: April 08, 2014, 09:05:49 pm
content: Thanks guys, just to be precise, the example A hasC106 = 10 nF, 5OOV, Ceramic DiscR103 = 220k Ohm, 5%, 1/4W, Compositionthe example B:C401 = 10 nF, 5OOV, Ceramic DiscI don´t see any reason for the R103 to be there.BTW Why we must filter our the grond point and not the power supply rails (VCC)?mumble mumble mumble...

author: linux-works
author_rank: Super Contributor
timestamp: April 08, 2014, 09:23:28 pm
content: digital will generate 'back hash noise' and inject it into the psu. its high freq stuff, not ripple from ac, so you want to shunt it to ground only for noise. for dc, you do not want that ground to equal chassis ground, in most cases.you will also find ferrite beads used to block HF noise on 5v logic lines, in many designs.
Use of current mirror - Page 1
Forum section: electronics / beginners

author: ShadowReaper
author_rank: Contributor
timestamp: May 08, 2013, 02:06:43 pm
content: Hello,as you already know, the current mirror provides a circuit with a current which is equal to the referenced current (Iref).My question is: why don't we just use the Iref itself to power the circuit and we use the mirrored current?

author: w2aew
author_rank: Super Contributor
timestamp: May 08, 2013, 02:12:51 pm
content: Quote from: ShadowReaper on May 08, 2013, 02:06:43 pmOften times, current mirrors are used to supply the same magnitude current to different circuits/loads. One reference can be mirrored many times to create many current sources tied to the same reference. Also, current mirrors can scale the reference current, thus creating current sources that are larger or smaller in magnitude by easily controlled ratios.
Use of cursor in DS1000 series - Page 1
Forum section: electronics / beginners

author: nbenm
author_rank: Newbie
timestamp: June 15, 2019, 08:24:11 am
content: When I set cursor to manual, a form of measurements appears.It makes moving the cursor quite impossible.How can I hide it ?I use a DS1054ZThanks in advance

author: GerryR
author_rank: Frequent Contributor
timestamp: June 15, 2019, 10:06:06 pm
content: The small button over the soft keys turns the main cursor menu off. You can then move the waveform horizontally to get it clear of the smaller cursor readout menu (The readout menu stays on until you hit the lighted Cursor activation button a second time.). You can manipulate the cursors without themaincursor menu being on the screen (just the smaller cursor readout menu is on) by depressing the multi-function knob; it moves cursor control between A, B and AB. (I have the DS1102D and am not sure if everything applies between it and the DS1054Z.) Hope this helps.
Use of diode in 555 pulse generator - Page 1
Forum section: electronics / beginners

author: rodcastler
author_rank: Regular Contributor
timestamp: March 23, 2024, 02:06:00 am
content: Hi!I came across this diagram for a simple pulse generator I needed. It looks fairly straightforward to me, and it allows me plenty of control over both the low pulse length and the high pulse length.What puzzles me though, is the presence of D1 (Top Left). I couldn't figure out what it would be for, and of course if I remove it from the circuit, it still works as expected.Is it just best practice, or am I missing something?Thank you.

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 23, 2024, 05:14:02 am
content: No, I don't see the purpose for D1 in your diagram. Perhaps they meant to do it like this, so that C1, if it was large, would get discharged if the power was cycled relatively quickly:
Use of multiple heat sinks on SBC - Page 1
Forum section: electronics / beginners

author: Seaofdep
author_rank: Regular Contributor
timestamp: September 09, 2017, 08:06:44 pm
content: HiOn my pine64 single board computer, only using one heat sink on the main... I have noticed others using around 4 or 5.My question is if using more heat sinks on such a small board actually beneficial and necessary and if so I have a few of these lying around that are tad bit larger than the component itself , will this be okay , should I cover them all and what is the right adhesive to use ?Thank youSent from my iPhone using Tapatalk

author: Benta
author_rank: Super Contributor
timestamp: September 09, 2017, 08:35:35 pm
content: Why on earth use a heat sink at all, let alone 3 or 4 on a Pine64? Seems completely pointless to me. None of the chips consume enough power to make heatsinking necessary.Unless you are talking about a different board than the quad-core ARM SBC?

author: Seaofdep
author_rank: Regular Contributor
timestamp: September 09, 2017, 09:49:37 pm
content: Quote from: Benta on September 09, 2017, 08:35:35 pm– 1.2 Ghz Quad-Core ARM Cortex A53 64-Bit Processor. Executes both 64 and 32 Bit for scalable high performance– Dual I/O expansion slots– Dual Core Mali 400 MP2 Graphics card– 2GB DDR3 Memory– Integrated Display engine with HDMI 1.4a– 10/100/1000Mbps Ethernet Port.I received mine second hand and already had one . It does run a bit warm after a bit of use. With research and youtubing I noticed a lot of them with more than just one heat sink. I'm new in this field but thought it was odd to have so many on the other hand maybe being new I was lacking the knowledge of why they are neeeded.So your saying it is fine the way it is and I need not worry about not having more than just the one ?Thank you for your replySent from my iPhone using Tapatalk

author: Seaofdep
author_rank: Regular Contributor
timestamp: September 11, 2017, 06:44:43 am
content: Quote from: wilfred on September 10, 2017, 03:33:43 amThank you for such a detailed reply . I don't see why Not If it will do no harm adding them , the wifi bluetooth module is on the right of the board and sits above the board and will not be affected. You know what type of adhesive to use use ? Much appreciatedSent from my iPhone using Tapatalk

author: wraper
author_rank: Unknown
timestamp: September 11, 2017, 09:10:23 am
content: I't pointless to use heatsink on anything other than SoC(CPU). I often see such thing on raspberry Pi, people put heatsink on USB/ethernet hubwhich never gets that hot anyway.
Use of power adapters - Page 1
Forum section: electronics / beginners

author: paul18fr
author_rank: Contributor
timestamp: October 04, 2014, 07:41:07 am
content: Dear AllI've plenty of power adapters (15V@2A, 12V@1A, 9V@1A and so on) coming from various electrical devices; I've been thinking "can I use them to replace a step-down transformer (in a first stage at least) ?": serial mounting for example ...I'll probably have to use voltage regulators in order to smooth the signal (I'm saying that because I don't have a scope yet and hence I cannot test it).Of course I'm thinking if it were so easy, many contributors would have proposed it, so is it a waste of time ? is there something I have to care about (I'm thinking for example in the seft heating of the adapters) ?NB: I'm pleased in thinking that's a way to "recycle" this kind of devices that I was used to throw away in the past (bad habbit)Thanks for any advice or feedback ...Paul

author: Paul Price
author_rank: Super Contributor
timestamp: October 05, 2014, 01:01:37 am
content: A power supply is a power supply, you can use these discarded power supplies to power your projects and if you add a LM317 on a heatsink you can have a nice tiny bench supply that is well-regulated, adjustable and current limited.There is a lot of not so hard to understand info about LM317 regulators in their spec. sheet and on this forum.The main concern is to not overheat them by operating them at currents exceeding the rating shown on their cases. So watch out for short circuits and power supplies that are getting too hot to touch. If overloaded, most will quickly blow a tiny fuse located on the transformer winding to prevent smoke and fire hazards.I use them all the time to work with experimental circuits.
Use of secondary oscillator - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: June 11, 2024, 04:34:40 am
content: In this device datasheet, (https://ww1.microchip.com/downloads...and-WFI32E01-Family-Data-Sheet-DS70005425.pdf) , my part is WFI32E02, what is the use of SOSCI/SOSCO pins?Like, are they mandatory for the working of WFI32E02? Or are they optional?Going through the datasheet, I see that, we require a crystal on the SOSCI/O pins (page 633), if we want to have some flexibility using Bit 12 in Register 38-3.Can someone clarify.Working Datasheet Link:https://ww1.microchip.com/downloads/aemDocuments/documents/WSG/ProductDocuments/DataSheets/PIC32MZ-W1-and-WFI32E01-Family-Data-Sheet-DS70005425.pdf

author: ledtester
author_rank: Super Contributor
timestamp: June 11, 2024, 04:47:53 am
content: Quote from: Freshman on June 11, 2024, 04:34:40 amThe link doesn't work, try this one instead:https://ww1.microchip.com/downloads/aemDocuments/documents/WSG/ProductDocuments/DataSheets/PIC32MZ-W1-and-WFI32E01-Family-Data-Sheet-DS70005425.pdfMy reading is the SOSCI/O pins may be connected to a 32.768 KHz crystal or may be used as digital input pins.See:- footnote 4 on page 5- description of pins A59 and A58 on page 38QuoteI'm not sure I understand what you are saying here.My guess is that the SOSCSEL bit selects between these two modes. If you have a crystal on the SOSCI/O pins you should probably set SOSCSEL to 1. If you want to use A58 and A59 as digital inputs you should set SOSCSEL to 0.

author: aliarifat794
author_rank: Regular Contributor
timestamp: June 12, 2024, 09:52:13 am
content: The use of the SOSCI and SOSCO pins is optional. They are not required for the basic operation of the WFI32E02 microcontroller. If your application does not need the precise timing functions provided by the secondary oscillator, you can leave these pins unconnected.
Use of transformer with 3 coils each having 3 turns - Page 1
Forum section: electronics / beginners

author: petert
author_rank: Regular Contributor
timestamp: December 14, 2019, 08:45:57 pm
content: Hello,I disassembled a CCFL light bulb/energy saving lamp. It has what looks like a toroidal transformer, with 3 coils each having 3 turns only.I assumed the point would be voltage conversion, but since each of the coils have the same number of turns (even if some are slighty more dense than others), I would assume they don't have much of an effect.What use would such a component have?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 14, 2019, 09:24:01 pm
content: Trace two of the windings back to the base-emitter circuit of the two transistors. I think you will find it's a rather critical part of operation.Tim

author: Zero999
author_rank: Super Contributor
timestamp: December 14, 2019, 09:48:44 pm
content: The transformer actually drives the transistors.There are some specialised CFL driver ICs, but most lamps use the same basic circuit. See the links below.http://educypedia.karadimov.info/library/AN00048.pdf#page=11&zoom=auto,-90,632http://diycarmaint.blogspot.com/2017/11/ccfl-or-cfl-lamp-repair-energy-saver.html

author: james_s
author_rank: Super Contributor
timestamp: December 14, 2019, 10:03:40 pm
content: The circuit is called a Royer oscillator. They have some disadvantages but it's hard to beat the simplicity. I actually hacked one together out of parts I literally found on the floor once and it worked on the first try, transferring enough power to light a 12V incandescent bulb.