hybridfree/eevblog-posts huggingface dataset:
Trickle charging "not to be used" yet it is the reccomended circuit on datasheet - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: November 07, 2024, 11:49:33 pm
content: Hi,with respect to the attached datasheet, at the bottom it says "Under no circumstances trickle charging should be used".But just below it they show the schematic of trickle charging saying it is the right charging circuit.Can someone please explain?Thank you

author: Manul
author_rank: Super Contributor
timestamp: November 08, 2024, 12:36:49 am
content: Trickle charging is feeding current with a compliance voltage above battery max charge voltage. Notice that the crossed out "wrong" circuit has a source voltage of 5V, thus there will be some charge current going even when battery voltage reaches it's maximum 3.55V. In the second circuit, with 3.6V source and a diode it is impossible. So second circuit is by definition not a trickle charger, it will never try to push the battery above 3.55V.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: November 08, 2024, 12:42:30 am
content: Reread the datasheet. Take every line literally. The problem is allowing the voltage to rise above 3.4 +/- 0.15 volts. See note 1 above the schematics you reference.The two schematics are different in an important aspect. The left, a classic trickle charge concept has a 5.0 V supply and a resistor to limit maximum current. The right circuit has a 3.6 volt supply with a diode in series. For all practical purposes it keeps the voltage from rising about the specified limits. There will be sufficient leakage in all but very rare cases to keep the diode drop higher than 0.05 V.The left circuit would be totally acceptable if the supply was 3.4 V. It might not meet all folks definitions of a trickle charge circuit under that condition.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 08, 2024, 01:01:35 am
content: Yes the caution title is to make sure readers notice it, but you need to read the whole paragraph to understand what needs to be taken care of.It's trickle charging with any circuit allowing the cell voltage to rise past the maximum recommended, which is 3.4V (I would personally recommend not exceeding 3.2V for ensuring longer lifespan), that is to be avoided.So, in current terms, we would call that paragraph's title a clickbait.

author: ricko_uk
author_rank: Super Contributor
timestamp: November 08, 2024, 03:48:02 am
content: Thank you all!That now makes sense.

author: amyk
author_rank: Super Contributor
timestamp: November 08, 2024, 04:02:00 am
content: These are cells meant to be float-charged, i.e. kept at the full voltage most of the time.Note that "1000 cycles at 10% discharge" spec - these aren't meant to be fully charged and discharged like most other cells are, and are intended for backup power.

author: ricko_uk
author_rank: Super Contributor
timestamp: November 09, 2024, 05:03:48 pm
content: Thank you Amyk,yes I am using it as a RTC backup battery.
Trigger Question - Page 1
Forum section: electronics / projects

author: sgpee
author_rank: Contributor
timestamp: April 20, 2011, 09:06:07 am
content: Hi All,Rookie question. I have a 100Mhz Digital Osciloscope (Rigol). How do I use Trigger properly?My scenario is as follows. I have the data I am interested in CH2 and CH1 is the Trigger (i.e. use GPIO to toggle and look at the data on CH2). I cannot get the CH1 trigger to work properly. What am I missing?Here is what I do..1. Connect Ch1/2 properly2. Go to trigger menu, select CH, rising edge, set the threshold to 1.5V (it is a 3.3v trigger)3. Press Run (i.e. I see the CH2 data nicely, CH1 is low)4. Hit acquire and wait for trigger to kick inthis never happens.. (i.e. I cannot get scope to acquire the data after the trigger point)Help is appreciated.. I couldn't find a good tutorial somewhere unfortunately and there is no body to ask. (ps. I know CH1 going up, so it is not a software issue, I just don't know how to use trigger properly)Thx,Sgpee

author: scrat
author_rank: Frequent Contributor
timestamp: April 20, 2011, 09:16:04 am
content: The scope is running by default. By pressing "run" you should actually stop it (IIRC the button switches to red light), the button is like a "play-pause" button on a music player.The "acquire" button should be only for going to the acquisition options (sample, peak, averaging, ...) which aren't related to trigger.If you're trying to capture data once you should use the single mode, otherwise it will trigger at every condition match (normal) or at matching condition and after a timeout (auto).Although Rigol is not so good at documentation, the scope manual (search on the internet) should report this things.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 20, 2011, 10:32:43 am
content: check probe attenuation 1x? 10x?trigger mode should be auto or normal

author: tnt
author_rank: Regular Contributor
timestamp: April 20, 2011, 11:58:50 am
content: * Check probe attenuation and config in scope (so that the 1.5v is really 1.5v)* Put the trigger in "Normal" mode instead of auto to prevent 're-trigger' after a timeout* (or optionnally us the 'single' mode)

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: April 21, 2011, 06:06:57 pm
content: Start by loading "Deafult setup" to give you reasonable repeatable initial settings.
trimmer related phenomena when tuning my YIG - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: August 13, 2024, 07:46:04 am
content: Hello ,I have a very weird phenomena my YIG has a tune input.When I used LD1084 regulator and one of the resistors was a trimmer even thow i put 10uF capacitors on the output and input .When i try to tune my voltage going into the YIG the YIG starting to jumps 300MHZ 500MHZ back and forth.So i suspect the TUNE voltage have jumps of 1V at least.I suspect that when I changed the trimmer value it created this behavior.A basic voltage divider get my YIG better stability then this thing.1.Am i correct in my assumption?2. Why the trimmer could create such a thing?3.what could be manual tuning alternative for changing of resistor?https://www.st.com/resource/en/datasheet/ld1084.pdf

author: eutectique
author_rank: Frequent Contributor
timestamp: August 13, 2024, 09:55:25 am
content: Quote from: john23 on August 13, 2024, 07:46:04 amDo you have an oscilloscope?

author: john23
author_rank: Frequent Contributor
timestamp: August 13, 2024, 10:08:06 am
content: Hello, Is there a better way manually changing the voltage?maybe some other type of trimmer to use with a regulator?Thanks.
Trimming 16MHz crystal in production for BLE??......... - Page 1
Forum section: electronics / projects

author: Smokey
author_rank: Super Contributor
timestamp: May 29, 2022, 10:30:06 pm
content: I'm making a (hopefully) standalone production test fixture for a product with bluetooth. The DUT has a 16MHz crystal, and from what I understand that needs to be +/-50ppm max for BLE to work. I can output the clock on a GPIO for measurement and the DUT micro has trim capabilities built in, but I need to accurately measure the clock and get that data to the fixture processor to set the trim.Because I plan on making many of these fixtures, I would rather not have a boat anchor frequency counter hooked up to each one. Cost is also always an issue for many fixtures. Something self contained that doesn't itself require calibration would be optimal.What are the best options for measuring a 16MHz clock accurately enough (+/-5ppm?) to perform this trim in a formfactor that is ideally board mounted, self contained, and inexpensive?

author: exmadscientist
author_rank: Frequent Contributor
timestamp: May 29, 2022, 10:36:30 pm
content: I always just buy a better crystal. It quickly pays for itself in test complexity.

author: Smokey
author_rank: Super Contributor
timestamp: May 30, 2022, 02:48:03 am
content: Normally I would agree that a better crystal is easier. In this case, they recommends both +/-10ppm spec and trimming, which is done entirely in software (no external caps). Better than 10ppm gets a little exotic.You got it with the crystal frequency effecting the RF output. That's the concern. I don't have a spectrum analyzer in the production test setup, but that would probably work trimming it that way. But at that point a counter would be easier/cheaper I think.
Trimming pins of a DIP - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 18, 2022, 04:46:38 pm
content: So I've been tearing 8 bit things apart and I notice that to make a CERDIP EPROM fit on a socket in a Commodore 64 game cartridge, the pins have to be shortened by ~0.5mm.It looks very regular and machine made, were DIPs available with different pin lengths or was there a kind of pin-cutting press available?

author: jpanhalt
author_rank: Super Contributor
timestamp: September 18, 2022, 06:57:33 pm
content: Stick the chip you want to trim though appropriate thicknesses of 0.1" perf board and run a chisel or other cutter, but not your fine wood chisels, across them. An adeptly held Dremel with a cut-off wheel will do the same.

author: ajb
author_rank: Super Contributor
timestamp: September 18, 2022, 11:09:08 pm
content: Yes, tools to form and/or cut leads are an essential part of volume assembly of PTH parts. Whole tubes of DIP components are reels of axial or radial parts could get run through machines to cut and form their leads to the appropriate shape and length before getting inserting into the PCB. Lead forming and cutting capabilities can be incorporated into automated insertion machines so it's just load reels or boxes of parts in the machine and go. That's still a common practice for volume PTH assembly, but aside from legacy designs that are still getting manufactured there probably aren't a lot of DIP ICs moving through machines like that these days. Things like power supplies that still use a lot of PTH parts seem to be increasingly putting the higher complexity circuitry, including ICs, onto SMT daughter boards that get soldered onto the main PCB--at least where they aren't gluing and wave soldering ICs to the bottom of the board, which is a technique that's been around for a long time.There are also lower volume manual tools available, like specialty pliers for the same purpose, and even tools for forming IC leads from their raw leadframe state if you're in a REALLY low volume custom package situation.

author: Fire Doger
author_rank: Regular Contributor
timestamp: September 18, 2022, 11:37:54 pm
content: At my job they have something similar to this.It has a metal blade on a pneumatic piston which slides beneath a perforated plate.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 19, 2022, 12:39:41 am
content: That's crazy! Well I've never seen anything like that tool. Pin straighteners and lead-frame bender/choppers, sure, but nothing like that.OK I think I'll just use a pair of cutters for this one chip, that tool looks expensive...

author: eugene
author_rank: Frequent Contributor
timestamp: September 19, 2022, 09:09:37 pm
content: What bad thing would happen if the chip sat a little high in the socket?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 19, 2022, 09:35:02 pm
content: Both halves of the cartridge won't fit together. It's not like it's going to space or anything, but it looks goofy.
trimpot modification - Page 1
Forum section: electronics / projects

author: daniel444
author_rank: Regular Contributor
timestamp: March 14, 2019, 05:46:46 am
content: hi, i have just realized this useful modificationyou can solder a small resistor the brass trimpot so you don't need a screwdriver every timefirst polish the brass bit with a dremel or fileuse a small size resistor so it solders quickly so it dont overheat the plastic

author: tkamiya
author_rank: Super Contributor
timestamp: March 14, 2019, 05:33:54 pm
content: That's an interesting idea!However, trim-pots are made to be adjusted once and be left alone. Maybe occasional calibrations but surely not a substitute for a proper multi-turn potentiometers. I have seen them get very lose and not hold a value. Also, you don't want accidental changes. The idea is great, though.

author: coppercone2
author_rank: Super Contributor
timestamp: March 14, 2019, 06:25:43 pm
content: A SCREW DRIVER is actually not the right tool for the job.What you want is a trim pot adjustment tool. They are like a screw driver with a recess around the spade bit, like a socket wrench thats round, so you don't slip while you are adjusting them.And check the datasheet to see how many adjustments your trimpot is rated for. For long term use you want a big potentiometer.I do like the idea though.
Trip Amplifier Circuit - Page 1
Forum section: electronics / projects

author: andybarrett1
author_rank: Regular Contributor
timestamp: October 24, 2015, 08:52:19 pm
content: Hi AllThank you for reading .... I have a need for a simple Trip Amplifier circuit .... They used to be all over the industrial world ... But not so much now !Basically something that looks at a 4-20ma signal and trips a low or high relay depending on my set points. I am at this moment thinking of using a 339 comparator and a couple off bc108 driven relays.But. I was wondering if anybody had any better ideas or maybe a PIC controller might do job better ?I am open to any thoughts .... thank you for readingAndy

author: Marco
author_rank: Super Contributor
timestamp: October 24, 2015, 10:00:22 pm
content: Still quite a few new trip amplifiers for sale, mostly in Britain for some reason.Could use a TL431 with that BC108 as well.

author: Seekonk
author_rank: Super Contributor
timestamp: October 25, 2015, 07:26:40 am
content: A TL431 is a great choice if you like component level building. These easily drive small relays by themselves if a dry contact is needed. I am getting spoiled by those Arduino clone mini328 boards that can be bought for $2-3 for these small jobs. If a switch transition at a set voltage was all you wanted, life would be simple. When you add in time delays and hysteresis a small micro wins hands down. In my opinion spending 75 cents more for the gold boards is worth it.

author: andybarrett1
author_rank: Regular Contributor
timestamp: October 25, 2015, 09:08:10 pm
content: HiLooking at the TL431.... But it looks a little sensitiveBRAndy
Tripling My Nexus 6P's Battery Life - Page 1
Forum section: electronics / projects

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: November 28, 2016, 02:55:47 am
content: I'm not a fan of today's phones and their compromise for thinness over battery life.Of course, I could just make an external battery case, but I had a crazier idea: Remove the back cover completely, and make a new back/case combo on my 3D printer, and just connect a bigass lithium battery to the existing one. This means I could relocate the fingerprint scanner, something that has been stopping me from making a battery case. The fingerprint scanner is on the back, and would end up being covered by a battery if I were to make a non intrusive battery case.The nexus 6p doesn't seem TOO hard to take apart (with the microsoft surface being an obscene pain in the ass) according to an ifixit teardown:https://www.ifixit.com/Teardown/Nexus+6P+Teardown/51660If I were to get inside the battery's outer sticker (gaining access to the battery terminals) and connect another lithium battery to it, would the phone/battery BMS re calibrate capacity? If I were to increase the phone's battery from 3.5Ah to 10Ah, would I need to make other mods?Thoughts? Ideas?

author: Rerouter
author_rank: Super Contributor
timestamp: November 28, 2016, 08:32:21 am
content: The battery management ic is inside the battery I think.. otherwise it would get confused every time you swapped out the battery in a replaceable model.If it's one where the battery is sealed in, it likely won't correct for it, and instead stop charging early as a protection feature.

author: amyk
author_rank: Super Contributor
timestamp: November 28, 2016, 09:00:00 am
content: Most replaceable phone batteries I've seen are just +/-/thermistor and the BMS just uses a combination of voltage and internal resistance (current) sensing.
Trivial Socket Related Question - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: February 15, 2023, 01:02:02 pm
content: So I'm building an Isolation Transformer in a box... 240V in one side and 110V isolated out the other...First I was going to drill a hole and have a flying lead with a 2 pin Mate N' Lock adapter which ultimately will connect to the Arcade CRT monitor I hope to fix and then I thought it might be nice to have it adaptable to other devices so thought a 110V outlet socket would be good and then a flying lead with connectors on both ends.Anyway... I have settled on...Is this a poor choice given the prongs will have 110V on them? What would be a better socket?

author: wasedadoc
author_rank: Super Contributor
timestamp: February 15, 2023, 02:17:34 pm
content: Quote from: NivagSwerdna on February 15, 2023, 01:02:02 pmYes.https://sinolec.co.uk/en/c13-iec-connectors/257-iec-socket-c13-outlet-0718-1-pw.html

author: NivagSwerdna
author_rank: Super Contributor
timestamp: February 15, 2023, 03:33:24 pm
content: Nice; much better solution.Added a C13 Socket to my shopping basket and also ordered a C14 cable which I will terminate with my special connectors.Thanks!

author: themadhippy
author_rank: Super Contributor
timestamp: February 15, 2023, 03:51:25 pm
content: QuoteNO ,its 3 pole so could lead to the expectation there's an earth.something likewould be a safer choice

author: wasedadoc
author_rank: Super Contributor
timestamp: February 15, 2023, 04:58:02 pm
content: Quote from: themadhippy on February 15, 2023, 03:51:25 pmNo reason why the earth pin of the socket should not be connected to mains earth.

author: themadhippy
author_rank: Super Contributor
timestamp: February 15, 2023, 05:03:21 pm
content: Quoteapart from defeating the whole point of building an isolating transformer

author: wasedadoc
author_rank: Super Contributor
timestamp: February 15, 2023, 05:14:27 pm
content: Quote from: themadhippy on February 15, 2023, 05:03:21 pmIt does not defeat "the whole point of building an isolating transformer". The power output pins of the socket are isolated from mains.
Trnasistor Datasheet Cross Reference Verification - Page 1
Forum section: electronics / projects

author: bostonman
author_rank: Super Contributor
timestamp: August 28, 2022, 11:53:47 pm
content: I have a transistor (believe MOSFET) from a car repair project I'm working on (see attached).I'm looking for the datasheet and all I'm finding is SFS9644.Does anyone know if this is the same transistor?

author: Benta
author_rank: Super Contributor
timestamp: August 28, 2022, 11:58:23 pm
content: 9644 is prolly the date code (1996, week 44).Part type? no idea, could be custom marking.

author: bostonman
author_rank: Super Contributor
timestamp: August 29, 2022, 12:30:17 am
content: It could be.It's from an Engine Control Module in a 97 Buick. This particular area has six of them and I believe each one controls each fuel injector. One injector isn't firing, and, ironically, this transistor measured different resistance on all three legs compared to others.From what I can tell, one pin is ground, the other goes to the fuel injector (which has two pins - one is common 12V to all the other injectors, and the other pin is the other side of the 12 ohm coil in the injector which goes to this transistor via the harness), and I haven't traced the third pin yet.Initially I assumed a transistor, but once I removed it from the circuit, it began measuring like a MOSFET where if I put the meter on diode, it seems to charge the gate and keep the MOSFET closed.This device is either bad, was bad and somehow began working correctly due to applying heat to remove it, or something else on the third pin that I need to trace is causing different resistance.Either way, I was hoping to start with the datasheet and maybe find a replacement to buy.

author: floobydust
author_rank: Super Contributor
timestamp: August 29, 2022, 12:33:41 am
content: IR2248 or IRF2248 is a Delphi fuel injector driver but I could not find out more.

author: bostonman
author_rank: Super Contributor
timestamp: August 30, 2022, 02:21:46 am
content: Thankfully it looks like maybe all that was wrong was a broken trace from the far left pin (I assume the gate) to its destination.Initially I traced the fuel injector to this MOSFT, did a resistance check on the pins, compared it to the other identical circuits (I assume they're identical since they each control a different number fuel injector), and noticed the resistance was different.Thought the device was open until I removed it and seemed to be measuring correctly. After, I realized the trace was questionable, and then determined it wasn't connected.I'd still like to find the datasheet for this, but hopefully I won't need it. Hard to say if that's the date code because it is a 97 car which would mean they component would be hot off the press, shipped to the board house, built, installed in the car, shipped to the dealership, etc... all within a few months.
Trouble bridging HDMI to DSI using TC358870XBG - Page 1
Forum section: electronics / projects

author: tardiGrade98_
author_rank: Newbie
timestamp: December 21, 2020, 05:28:47 pm
content: Hello,For a while now I have been attempting to drive a MIPI display using my own firmware. As far as I can tell, the setup for the screen is successful, it asserts OLED_EN, and communicates the correct EDID data to the source, and yet no images show on the DSI panel. All I get are the white horizontal lines you can see on the picture I attached. The screen came with a driver board and was working out of the box. But I need to replicate the factory Firmware. I sniffed the I2C packets between the MCU (STM32) and the Toshiba HDMI-MIPI bridge (TC358870XBG), from there I reconstructed the setup file for the TOS chip and the panel, but instead of showing bridged images from the HDMI source, I get the white horizontal lines. Has anyone been in my situation, or had similar issues with a MIPI panel before?Display:https://www.aliexpress.com/i/4000192657266.htmlRegards,

author: vitalic66
author_rank: Newbie
timestamp: October 09, 2022, 02:07:42 pm
content: Have you ever been able to fix this?I also need a special FW to drive a special display with other resolutions.Regards

author: dajanchar
author_rank: Newbie
timestamp: December 25, 2022, 03:25:39 pm
content: Hello,I have ordered a round LCD display from china, where I have similar issue. The LCD and HDMI-MIPI board were ordered separately, which I presume is the issue because the LCD display is not working. HDMI link is detected OK (based on green LED), however only backlight of the LCD is enabled. I have also dumped I2C traffic and so far, everything looks OK regarding configuration itself. Basically the board configures HDMI-MIPI bridge to use both MIPI channels.If you want we can connect on some chat and discuss the issues further in more technical manner. I can provide my version of FW / I2C configuration so you can test it for yourself.
Trouble changing i2c address for ATECC608B chip - Page 1
Forum section: electronics / projects

author: metzger
author_rank: Newbie
timestamp: April 23, 2025, 04:42:23 am
content: I have been trying to communicate via I2C with the ATECC608B-SSHDA-T chip, which can be found along with its data sheet here (https://www.mouser.com/ProductDetail/Microchip-Technology/ATECC608B-SSHDA-T?qs=W%2FMpXkg%252BdQ4BTO4aB8XMhA%3D%3D&srsltid=AfmBOoonE-Ds2RX7FAp4O0XoM_nWhC-SokrG5X--Vh13sH4cgTmu4FAB). Everything mostly seems to be working for the most part, but I have been unable to successfully use the one time changeable I2C address that the data sheet specifies. Just for context, I have been using the cryptoauthlib GitHub library (https://github.com/MicrochipTech/cryptoauthlib/tree/5135c92c9b150154d72535cf4b82eb7d82e20f6e/lib) in order to communicate with it with an STM32 microcontroller dev board. I have been able to use the UpdateExtra command to change the specified address to 0x58 in the config zone. My config zone now has the following output:Config Zone:01 23 25 A5 00 00 60 03 47 CA AF 9B EE 61 4D 00C0 00 00 00 83 20 87 20 8F 20 C4 8F 8F 8F 8F 8F9F 8F AF 8F 00 00 00 00 00 00 00 00 00 00 00 0000 00 AF 8F FF FF FF FF 00 00 00 00 FF FF FF FF00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0000 00 00 00 00 B0 55 00 FF FF 00 00 00 00 00 0033 00 33 00 33 00 1C 00 1C 00 1C 00 1C 00 1C 003C 00 3C 00 3C 00 3C 00 3C 00 3C 00 3C 00 1C 00I have also been using atcab_release() in conjunction with this after the config zone was changed to ensure I put the device to sleep so the changed address would go into effect. I have attempted this with both locking the config zone afterwards and with the config zone unlocked. however, the data zone has remained unlocked. as you can see, the Config = B0, which is (0x58 << 1) for proper I2C communication with the cryptoauthlib library. Additionally, before I changed the address, the config = 00, meaning that it had not been changed yet.However, in every attempt of mine to wake up the device, scan the i2c bus, or employ the atcab_init(&cfg_ateccx08a_i2c_default) function, I only get proper responses from the old default i2c address of 0x60. I have been following this rough outline for how to do this process, but it still does not seem to be working.// Step 1: Initialize at default addresscfg_ateccx08a_i2c_default.atcai2c.address = 0xC0;atcab_init(&cfg_ateccx08a_i2c_default);atcab_wakeup();// Step 2: Change addressuint8_t new_addr = 0xB0; // New 8-bit I2C address (e.g., for 7-bit 0x58)atcab_updateextra(0x01, new_addr);// Step 3: Put the device to sleep so it reloads the addressatcab_release(); // ✅ This sends the SLEEP command internally// Step 4: Delay to let device settleHAL_Delay(100);// Step 5: Init again with new addresscfg_ateccx08a_i2c_default.atcai2c.address = new_addr;atcab_init(&cfg_ateccx08a_i2c_default);atcab_wakeup(); // Now should talk to new addressMy overall goal is to communicate with multiple of these ATECC608B-SSHDA-T chips on the same I2C bus, so I need to be able to change their I2C addresses for functional communication. Please help!!!!
Trouble driving MOSFET (DC motor controller) - Page 1
Forum section: electronics / projects

author: Russ314
author_rank: Contributor
timestamp: July 31, 2021, 03:06:46 am
content: I have a 120v dc motor that I'm powering with a +/-65v supply. The circuit works in simulation, but in practice, the output is... less than squarewave. I can't figure out what's going on.
trouble faking monitor EDID through VGA with arduino uno - Page 1
Forum section: electronics / projects

author: memeMagician
author_rank: Newbie
timestamp: July 10, 2017, 07:11:07 pm
content: I'm trying to make a device to get my computer to output signal through VGA as if there were a monitor connected, but I haven't been able to get it working. I've never used I2C before and I'm new to electronics in general so I'm assuming I've overlooked something simple. Currently I've got an arduino uno wired directly to a VGA cable (ground to ground, SDA to ADC4, SCL to ADC5) and plugged into the USB port of the computer. I'm using the following program, the values were generated by an EDID editor I found online.Code:#include <Wire.h>byte output = {0, 255, 255, 255, 255, 255, 255, 0, 50, 242, //0 checked0, 0, 0, 0, 0, 0, 0, 19, 1, 3, //1 checked10, 52, 32, 120, 34, 236, 24, 163, 84, 70, //2 checked152, 37, 15, 72, 76, 0, 0, 0, 1, 1, //3 checked1, 1, 1, 1, 1, 1, 1, 1, 1, 1, //4 checked1, 1, 1, 1, 46, 9, 128, 160, 32, 224, //5 checked14, 16, 48, 32, 52, 0, 128, 224, 33, 0, //6 checked0, 26, 119, 1, 0, 160, 16, 144, 14, 0, //7 checked48, 32, 53, 0, 0, 144, 16, 0, 0, 26, //8 checked0, 0, 0, 252, 0, 116, 111, 112, 32, 107, //9 checked101, 107, 32, 32, 32, 32, 32, 32, 0, 0, //10 checked0, 253, 0, 56, 60, 22, 48, 3, 4, 10, //11 checked32, 32, 32, 32, 32, 32, 0, 151 }; //12 checkedvoid setup() {Wire.begin(50); // join i2c bus with address #50Wire.onRequest(requestEvent); // register event}void loop() {delay(1);}void requestEvent() {Wire.write(output, 128); // respond with message}From what I've read herehttp://read.pudn.com/downloads110/ebook/456020/E-EDID%20Standard.pdfit appears that the output data should be valid so I'm guessing it's a problem in the wiring or elsewhere in the code. If anybody knows what I'm doing wrong that'd be great.Also I noticed that the "on" light in the arduino turns on when I connect the wires before i connect power. Does this mean it's getting power from the I2C lines?

author: wraper
author_rank: Unknown
timestamp: July 10, 2017, 07:18:43 pm
content: Why are you trying to invent a bicycle? All you need is either just 3 resistors or programmed EEPROM IC, like 24C02.Did you use pull-up resistors as I2C cannot work without them?EDIT: I think it will work without them too. I recall there also should be resistors in graphics cards.

author: memeMagician
author_rank: Newbie
timestamp: July 10, 2017, 07:38:01 pm
content: I'll look into getting a few 24C02s to try. I would use 3 resistors but my VGA cable doesn't have wires going to those pins (it only has R, G, B, ground, SDA, SCL and two others which I haven't identified) and I need this to work through a VGA cable. I don't have pull up resistors though as you mentioned it likely doesn't matter (perhaps I should try anyways though)

author: wraper
author_rank: Unknown
timestamp: July 10, 2017, 08:51:59 pm
content: Quote from: memeMagician on July 10, 2017, 07:38:01 pmYou actually connect resistors between RGB outputs and ground.
Trouble finding exact resistor model number - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: December 26, 2018, 12:14:31 am
content: I need to replace a couple of resistors in my headphone amp as they were fried when trying to use the amp to power small loudspeakersThe original resistors are Dale 20 Ohms 1% T9 CMF55 0541.I bought two models with identical resistances but with different temperature coefficients 100 vs 50 PPM.The new ones have slightly different markings on them instead of T9 they're either T1 or T2 I assume this is for the different temp coeff. as mentioned above.That being said however, I have no clue what the original T9's specs areas i could not find its datasheet.Would it be ok to use either one

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: December 26, 2018, 12:36:22 am
content: I actually found out that the original resistors with a T9 value means that the TC is of 25 ppm.Will adding resistors with TC values of 50 ppm affect the circuit in any perceivable way?

author: mvs
author_rank: Frequent Contributor
timestamp: December 26, 2018, 02:26:08 am
content: Quote from: drummerdimitri on December 26, 2018, 12:36:22 amYou have not provided any schematics. What kind of answer you are expecting then?1%/25ppm is 400 Kelvin. If this amplifier really needs resistors with such low tempco, it will definitely require calibration after replacement.Perhaps also recalibration some time after to cope with aging.Or the manufacturer has used better parts, then actually needed.
Trouble pairing RN-42 with a gamepad - Page 1
Forum section: electronics / projects

author: seavan
author_rank: Contributor
timestamp: March 30, 2015, 10:52:10 pm
content: I am trying to use a bluetooth gamepad to control an arduino-based robot through RN-42. I cannot pair/connect the gamepad to RN-42. I can connect to the gamepad from my laptop and from Android phone. The gamepad is slave HID. RN-42 also seems working just fine. I am new to Bluetooth. I tried all SA and SM options. Tried using different SC and SD. Tried changing SE. Tried using SPP and HID profiles. I am getting NEW_PAIRING and CONNECT failed. Hoping someone can help me. Thank you!

author: seavan
author_rank: Contributor
timestamp: April 01, 2015, 12:13:58 am
content: I think I found a reason for the problem. The gamepad is an HID device and it requires an HCI device on the robot side. RN-42 user guide mentions that RN-42 needs a different firmware version to support HCI.
Trouble sourcing 40.5 Khz oscillator - Page 1
Forum section: electronics / projects

author: wassy
author_rank: Newbie
timestamp: May 25, 2019, 10:59:47 pm
content: Hi all,I'm trying to create a copy of the remote for my gas fire. I was expecting a classic IR blaster, but it turns out it is an ultrasonic transducer arrangement. I think I've successfully reverse engineered the circuit, but it seems it uses two slightly different frequencies to send the two different signals to open the valve and close the valve. These seem to be based on a couple of radial oscillators 40.000 Khz and 40.500 Khz if I am reading the marking correctly.Any idea how I can source these? I've found one listing for the 40.000 Khz oscillator on AliExpress but I cannot find the 40.500 Khz oscillator anywhere no matter how much googling I do. I've checked out mouser, RS, AliExpress, eBay and LCSC. Any thoughts?For anyone interested I've attached a picture of the remote and the schematic I have been able to decipher from it. I guess failing that I'd have to create the required frequency some other way. That is a bit beyond my electronics abilities at this moment, but I'd be happy to take pointers on where to start.

author: jmelson
author_rank: Super Contributor
timestamp: May 25, 2019, 11:54:33 pm
content: Quote from: wassy on May 25, 2019, 10:59:47 pmThese are not "oscillators", they are bare quartz crystals, of the tuning-fork style, similar to the 32.768 KHz crystals used in watches, etc.My guess is that they are totally custom parts.Here's a way to do it. Get a 10 MHz oscillator and build an 8-bit binary divider that can be preset toa division ratio of either 250 or 247. This will give 40000 Hz (for 250) or 40485 Hz (for 405).The 40000 is exactly on frequency, the 40485 is .03% low.Jon

author: wassy
author_rank: Newbie
timestamp: May 26, 2019, 12:07:54 am
content: HI Jon,Thanks for replying. Yes I realised after I posted that I actually meant crystals, not oscillators. Thanks for the tip. I'll have a look into it
trouble sourcing display modules (70x40mm) - Page 1
Forum section: electronics / projects

author: jpyeron
author_rank: Regular Contributor
timestamp: May 17, 2022, 06:24:54 pm
content: I not sure if there is an efficient way to search for a display module by size.I am trying to source a display that would be compliant with NEMA WD 6-2016. So the following constraint applies: 33.274x66.802 mm <= size <= 41.275x70.612mm .At this point none of the other requirements seem to be relevant. Desire high resolution, integrated touch, color.Help? thoughts?
Trouble with ADA2200 in Multisim - Page 1
Forum section: electronics / projects

author: john1998
author_rank: Newbie
timestamp: June 12, 2018, 07:46:04 am
content: I am trying to simulate ADA2200 in Multisim. The device is not readily available in Multisim library. So, I downloaded the SPICE netlist code for it from Analog Devices. I tried to make a component in Multisim using this code. But I am encountering an error (It was also commented in the code that it will work only for ADISimPE). But I need the simulation to be done in Multisim. I am attaching the code below. Please suggest how I can make ADA2200 model in Multisim.Any help would be very much appreciated!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 12, 2018, 09:31:42 am
content: 1. This is a hierarchical SUBCKT.Hardly a problem, just rearrange the statements in flat order. Unless there's something about scoping when that's done, I don't know. (If there is, it doesn't look like they're using it?)2. It appears to use these pre-installed library models:delayed_switch_V2HC74Dgen_switchBAS70-04/PSand maybe some others that I've glanced over. You'll have to try and find sources for them, or build them yourself. The "HC74D" in particular sounds enigmatic, unless by "D" they mean D flip-flop (i.e., 'HC74).It doesn't look like it's outright impossible to run in Multisim, but beware of convergence issues with XSPICE models, which this uses heavily.Tim
Trouble with DIY Benchtop Supply using ATX PSU - Page 1
Forum section: electronics / projects

author: IllNate
author_rank: Newbie
timestamp: May 01, 2018, 02:31:51 pm
content: If you're having trouble with this kind of project, you may find that the purple wire (5V always on), needs a miniumum load. The OCZ 600W supply I used required a load here to 'trick' the supply into turning on, without a motherboard attached.Now that I've completely exposed my lead, I'll explain. I'm actually not making a benchtop supply (since I have an adjustable one already). I'm using it to power a 3D printer I recently purchased. But I wanted to see how well it regulated the +12V line under load. But I could not get the supply to turn on. I found a data sheet which suggested minimum loads for the different rails, which I dutifuly followed. But nothing worked. I eventually gave up. Then an old computer was getting scrapped, so I hooked up the PSU to that, just for my own sanity. That worked, so time to revisit it again. While I was trying various combinations of load, I noticed the +5V always on line, stayed high for quite a while after switching the supply off. As I wanted to repeat my sequence from a truly off state, I threw a 10 Ohm load on there as well, and voila, it worked. No minimum loads required on the other rails at all, unless you want good voltage regulation. For example I found that after loading down the 12V lines with 120W each, I required a load on the 3.3V rail, otherwise the 12V rail would droop (probably meeting some 3.3V overvoltage condition).Other caveats: Short green to ground to turn on. Brown wire is 3.3V sense, so connect this to orange wires.Anyway, I ready many tutorials on benchtop ATX conversions looking for hints and did not come accross this hint. So I'm posting here (as well as a few comments on these tutorials) in the hopes it will help someone else.
Trouble with transistors  - Page 1
Forum section: electronics / projects

author: Neurotic Norman
author_rank: Newbie
timestamp: September 09, 2014, 06:23:01 pm
content: Hello all! So, I've decided to take on a project. I'm not sure how many would be familiar with W. Grey Walter's tortoises, but that's what I've decided I'd like to attempt. Now, I thought I'd attempt it with solid state components for simplicity and ease of use. The only issue is, the schematic is VERY vague. I've tried a circuit simulator, but I'm having trouble making it cooperate. So I thought I'd come here and see if anyone had any ideas as to what one could help with the conversion. I'll attach the schematics and a description of operation.Here's the theory of operation:http://www.beam-wiki.org/wiki/Grey's_TurtlesThanks in advance!

author: German_EE
author_rank: Super Contributor
timestamp: September 09, 2014, 07:25:23 pm
content: The first problem are the two grids, I know that a triode is a rough equivalent of a transistor but it has been years since I built something with a tube in it. Secondly there is the behavior detailed in the link you gave, it's so complex that a complicated transistor circuit could easily be replaced by an eight-pin micro and then the code modified to suit.If you DO find an equivalent circuit then please let us know but I suggest you save your sanity and use a microprocessor.

author: Neurotic Norman
author_rank: Newbie
timestamp: September 09, 2014, 07:49:37 pm
content: I see it didn't post the first time. I have a circuit that'll work. It's just not annotated. None of the resistors or capacitors have values. I thought I attached it to the first post, but I'll try on this one.I think the microprocessor approach might end up being six of one, half a dozen of the other. Unless I can find someone that can program in a language that's a little more up to date, I'll have to figure that one out too.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 09, 2014, 11:04:00 pm
content: That screen-and-grid connection is peculiar. A rising step change at the first tube (which is triode wired) will tend to maintain conduction in the second tube. But a falling edge will tend to turn it off (firstly because screen and grid voltages turn off), but after some time (determined by the grid RC time constant), the rising threshold will be lowered.I don't think it implements a "zero crossing tracker" sort of characteristic, but it's kinda sorta like that.Tim
Troubles with RFM69CW and data availability - Page 1
Forum section: electronics / projects

author: krish2487
author_rank: Frequent Contributor
timestamp: June 29, 2020, 08:58:06 am
content: Hello folks,I am back yet again with some help regarding RFM69 modules.The setup is as follows. We have one Rpi connected to a RFM69CW module acting as a gateway. To each gateway we have 12 nodes equipped with the same RFM69 modules, which collect and send data to the gateway. The nodes are running arduino code one an Atmega328 and the lowpowerlabs library. The Rpi is using the python library from the same source. The nodes transmit the data every two minutes. The nodes and the Pi are on the same network ID. The nodes expect and receive an acknowledgement from the Pi when they transmit a message.There is peculiar behavior we are seeing while running this setup.1.When only the Pi and the 12 nodes are running, there is near 100% data availability with very low data loss.2.When we add another Pi with 5 nodes, operating on another network ID, there is a noticeable ( ~ 15% on the worst node, but aboout 3-7 % on an average) of data loss on the first Pi.3.When we remove the second Pi with the 5 nodes, the data availability improves and goes back to near perfect on the first Pi.4.When we add another 8 nodes to the original Pi, making it a total of 20 nodes, the data quality remains more or less the same.Our understanding is that adding more nodes ( upto a certain point) does not degrade the data availability that drastically, but adding another similar setup on another different network ID causing an significant loss of data. Is our understanding correct?I was wondering if anyone here has seen such a behavior before with thr RFM69 modules.If so, how to mitigate such an issue.I will be grateful for any insights and suggestions on how to improve the data availability when running multiple such setups at the same time.
Troubleshooting a Sony Watchman FD-40A - Page 1
Forum section: electronics / projects

author: MathematicalJ
author_rank: Contributor
timestamp: March 15, 2020, 11:10:48 pm
content: I have a Sony Watchman FD-40A that I'm trying to use to display component video. The picture is wonky in either one of two failure modes:The picture appears with an oscillating vertical saw-tooth (first bit of the YouTube video below) with otherwise very dirty picture, orthe picture skews hard right from top to bottom dependent on how much and where brightness is on the screen.Here's a video demonstrating the issue. You won't want to watch the whole thing, just enough to get the idea.https://youtu.be/RGuaJqVHJno?t=34I can switch between these failure modes byturning the tuning dial.I have ruled a few things out:The video input connection is fine, as I get the same result when I tap directly into the video and ground traces.The video source works fine on other devices.A cleaner 6v power supply *does* clean up the vertical sawtooth slightly, but it's still there, and the picture generally looks like garbage.Before I start poking around at voltages, I thought I'd ask here to see if this is a common enough problem that someone knows what it is. The dirty video suggests a bad cap. I don't know what to think about the tuner making a difference.

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 16, 2020, 07:30:29 am
content: Component or composite video?The watchman models ever offered component video input.

author: MathematicalJ
author_rank: Contributor
timestamp: March 17, 2020, 01:19:08 am
content: Yes, sorry, I meant composite of course.

author: james_s
author_rank: Super Contributor
timestamp: March 17, 2020, 04:37:35 am
content: They're B&W so there is actually no difference. The green/sync component output is monochrome composite sync and will display just fine on a monochrome composite monitor. It can look slightly better since you won't get the chroma dots crawling around.That isn't really relevant to this issue though.

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 17, 2020, 12:30:36 pm
content: I would start by isolating the tuner section entirely, seeing as it's basically useless these days.Find the main driver chip, download a data sheet and find the composite video input pin.Then trace it back to the input jack. Somewhere along the way it'll probably split off to the tuner section, usually through a switch or similar.I've found that the manufacturers at least loosely follow the reference schematic in the data sheet (they are all pretty similar with the notch filters and stuff anyway) so it should be pretty easy to map the few caps, inductors and resistors between the input jack and driver chip.Then just desolder the closest component to that split heading towards the tuner.Once you have that isolated, you can start properly tracking down any other faults (like bad caps etc).Can you take a few decent photos of both sides of the PCB and internal construction etc?
Troubleshooting an optical chopper - and a bizzare motor - Page 1
Forum section: electronics / projects

author: ChristofferB
author_rank: Frequent Contributor
timestamp: January 05, 2021, 10:47:43 pm
content: Hi all!I just received a brookdeal 479 optical chopper (=ortec 9479) and it's not in the best shape electrically.The motor is full on all the time, even though the frequency should be adjustable via a potentiometer.Here's my main issues: the motor has 4 leads. 2 in the central smaller cylinder, see the pic below.Has anyone seen this before?How would the speed be regulated? Is it using its freq. Output as regulator, or is it just a pwm thing?Thanks, I'm at a bit of a loss after checking all the usual suspects!

author: doktor pyta
author_rank: Frequent Contributor
timestamp: January 05, 2021, 10:55:20 pm
content: This could be brushed DC motor with tacho generator for precise feedback.My guess would be that smaller cylinder is a tacho.

author: langwadt
author_rank: Super Contributor
timestamp: January 05, 2021, 10:56:40 pm
content: probably a DC tacho, so just a DC voltage proportional to speed

author: ChristofferB
author_rank: Frequent Contributor
timestamp: January 05, 2021, 11:26:59 pm
content: That was quick! Didn't know that existed but it makes perfect sense. There is a single op amp nearby, it's likely feedback for that, then!