hybridfree/eevblog-posts huggingface dataset:
Confusing codec or op amp issue after 40 hours - Page 1
Forum section: electronics / projects

author: loki42
author_rank: Frequent Contributor
timestamp: August 21, 2024, 02:16:48 pm
content: So I have an issue with a new design that occurs after the unit has been running for around 30-40 hours. I tested 8 units of the new board, all were fine after 24 hours. After 40 hours I tested them all again. On all units, the ADC side of the codec only captured a very low signal level (maybe 2% of the original). The DAC side still functioned correctly. The codec is a single chip with stereo in / out. The input runs through a 2 quad op amps that that convert to a differential signal for the codec. 2 of the op amps in the quad are used for the output. If I restarted a unit, just pull power and straight back in the unit is back to being functional. The op amps and the codec aren't hot to the touch, I don't currently have a thermal imager to check for hot spots, but the instant recovery for me suggests maybe not thermal?The codec is the clock generator, MCLK is from a crystal running into the onboard PLL of the Analog Devices part. CPU is clock receiver. The CPU doesn't log any errors and everything seems to be functioning normally from it's point of view. I can get and set registers on the codec via I2C and things look normal.What could be going wrong? Clock drift? Something weird with jitter? Op amps going weird because they don't like the load they are driving or they are oscillating some how? That sounds unlikely, there are no unused op amps and the output stage that is functioning fine uses the same op amp. Ground plane gets too hot? It's a 4 layer board with plenty of copper pour and thermal vias under the codec.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 21, 2024, 03:05:34 pm
content: This smells like a software bug to me - time related and happening with complete predictability on all examples. I'd be looking for a counter that overflows, maybe.I'm no expert: just my first thought. By the way, any chance of posting the schematic?

author: loki42
author_rank: Frequent Contributor
timestamp: August 21, 2024, 10:10:38 pm
content: I'll screenshot the important bit of the schematic. Counter sounds likely to me but I'm using analog Devices driver, with minimal changes. Haven't noticed any where I'm counting stuff in a stupid way.

author: loki42
author_rank: Frequent Contributor
timestamp: August 22, 2024, 02:00:01 pm
content: So I did a stupid thing. The problem was capacitor leakage in the input buffer. I'd made a minor change to one of my previous designs and not paid attention to why one resistor was there give the simulation worked basically the same without it...
Confusing datasheet: Resistor on data OUT of addressable LED? - Page 1
Forum section: electronics / projects

author: badrequest400
author_rank: Contributor
timestamp: November 04, 2023, 10:25:03 pm
content: The following datasheet, at the bottom of page 7 discusses the resistors needed to protect the signal input/output of addressable LEDs. The input resistor makes enough sense, having read a few posts scattered around the 'net but what I don't understand is R2. Is R2 connected to the third LED only? Every third LED? The very last LED in any chain? Every single LED? Normally, the output of addressable LEDs are just left not connected to anything, aren't they?https://datasheet.lcsc.com/lcsc/2301111010_XINGLIGHT-XL-1615RGBC-WS2812B_C5349954.pdf

author: Smokey
author_rank: Super Contributor
timestamp: November 04, 2023, 10:51:35 pm
content: I would say, any time you transition from the outside world and the led string. ESD doesn't care if your pin is an input or an output.

author: uer166
author_rank: Super Contributor
timestamp: November 04, 2023, 10:52:13 pm
content: R2 is a series source termination for the transmission line. So, place it wherever the length of that wire is getting "long". Normally that's between separate strips.

author: badrequest400
author_rank: Contributor
timestamp: November 04, 2023, 11:29:25 pm
content: Thanks, I get it now!
confusing resistor - Page 1
Forum section: electronics / projects

author: timelessbeing
author_rank: Frequent Contributor
timestamp: July 04, 2012, 08:22:56 pm
content: What would you say is the resistance of this resistor?

author: LEECH666
author_rank: Frequent Contributor
timestamp: July 04, 2012, 08:26:11 pm
content: Could be an inductor as well.http://www.elexp.com/t_induct.htmThe color codes read as:Green = 5Blue = 6Gold = x0.1 (Multiplicator)Silver = 10% (Tolerance)So it might either be a 5.6 Ohm 10% resitor or a 5.6 µH 10% inductor.My guess would be inductor tho, maybe someone else can verify this.Cheers,Florian

author: timelessbeing
author_rank: Frequent Contributor
timestamp: July 04, 2012, 08:29:10 pm
content: I hadn't thought of that. I do measure a resistance across it, though.

author: madires
author_rank: Super Contributor
timestamp: July 04, 2012, 08:37:38 pm
content: Hi!Quote from: LEECH666 on July 04, 2012, 08:26:11 pmhttp://www.elexp.com/t_induct.htmYou're right! It's an inductor.Cheersmadires

author: SeanB
author_rank: Super Contributor
timestamp: July 04, 2012, 08:41:53 pm
content: More likely to be an inductor, with the green body coat. It will have some DC resistance as well, you would have to connect it up to something other than a simple resistance check to be sure.Break it apart and you will see the wire. Trying a magnet will not be definitive, as most resistor end caps are steel, while inductors use a ferrite core as well.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: July 04, 2012, 10:03:01 pm
content: You're right! I put a few volts across it, and it picked up little bits of metal. I was confused because it measured 0.56 ohms which is so similar to 5.6. No wonder my circuits were acting strange! So how are you supposed to tell them apart? These components come in a whole rainbow of colours!

author: IanB
author_rank: Super Contributor
timestamp: July 04, 2012, 10:10:07 pm
content: Inductors usually have a brightly coloured coating and look fatter and more bulbous, while resistors usually come in dull colours and look thinner and more rectangular.
Confusion about nixie tube 74141 outputs - Page 1
Forum section: electronics / projects

author: rea5245
author_rank: Frequent Contributor
timestamp: January 08, 2018, 08:12:36 pm
content: Hi,I'm building a nixie clock. I've built the circuit except for the nixie tubes themselves, and I want to test it before soldering in the relatively expensive tubes.So I feed a BCD 1 into the 74141 chip and look at the outputs on a 'scope. Some of them show a steady 1.5V while others show 60Hz noise (so they're high impedance maybe?)What puzzles me is that the pin for driving the 1 digit is not unique. I.e. it's showing 1.5V but so are a couple of other outputs. I could understand if all the other outputs were high impedance and just the 1 digit were at 1.5V (because maybe it's tied to ground but there's some leakage current going through). But why are a couple of the other outputs showing 1.5V?Is this just a case of "everything will sort itself out once the circuit is completed with the nixie tubes and the pins aren't floating"? Or is there a real problem here?Thanks,Bob

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 08, 2018, 08:17:19 pm
content: The 74141 outputs are open collector meaning they need a pullup current source to make any sense, you could temporarily connect a resistor, say 10K from each output to vcc so your scope correctly displays the output state.

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2018, 08:17:32 pm
content: The 74141 has open collector outputs, so there will be no voltage on those pins without something external to pull them up.

author: rea5245
author_rank: Frequent Contributor
timestamp: January 08, 2018, 08:34:22 pm
content: But if the outputs are open collector, why would I be seeing 1.5V on some of them?

author: james_s
author_rank: Super Contributor
timestamp: January 08, 2018, 08:36:19 pm
content: Likely the protection diodes, leakage current, I assume you're measuring with a high impedance multimeter? You'll often get erroneous readings.Connect a nixie tube or use a pullup resistor and it will work. You cannot accurately test an open collector part with nothing connected.

author: rea5245
author_rank: Frequent Contributor
timestamp: January 08, 2018, 08:43:00 pm
content: OK. Thank you.- Bob

author: David Hess
author_rank: Super Contributor
timestamp: January 09, 2018, 01:17:02 am
content: Counterintuitively, a 1.5 volt output in this case is the off state. Inspection of the 74141 output stage reveals that when off, half of the outputs will produce a TTL high minus one Vbe as an output voltage which is indeed about 1.5 volts. The Vbe is from the forward biased base-collector junction of the cascode output transistor which will become reverse biased and high impedance once the voltage is raised by the load of 60 volts maximum.
Confusion About p-p Specification vs. Vp - Page 1
Forum section: electronics / projects

author: bostonman
author_rank: Super Contributor
timestamp: October 10, 2025, 01:00:17 pm
content: I may have just overthought something (as I sometimes do) and put my brain in a state of confusion, but want to confirm before I damage my meter.I have a Graphtec GL240 Logger and the specification between the +/- terminals is 110Vp-p (when the 100V scale is selected).The confusion is due to always associating peak-to-peak with a sine wave because it's going above and below ground; although if it had DC offset it would still have a peak-to-peak of the same voltage.If the GL240 spec is: 110Vp-p that's 55Vp, does this mean I can only measure a DC positive or negative voltage of 55V (i.e. 0V ground reference to 55Vp) on each channel?To be clear, can I measure (to use round numbers) +100V DC across the positive and negative terminals on one channel and -100V DC across the positive and negative terminals on another channel or am the limited 55V DC?

author: macboy
author_rank: Super Contributor
timestamp: October 10, 2025, 01:33:40 pm
content: I understand your confusion. The manual includes language such as "The analog input section can frequently have cases of impedance." (WTF does that mean?), and "Noise: 48 dB minimum", which is a seriously high amount of noise. I might expect something more like "-48 dB maximum".It also states that the maximum voltage between an input terminal and ground is 60 Vp-p. I suppose this means that in the 100 V range, if one terminal (say, the negative terminal) is grounded or nominally at ground potential, then the maximum voltage at the positive input terminal is 60 V. The specs are very confusing with exceptionally poor use of the English language, and of non-English technical terms like "Vp-p". I think they meant to say the the maximum voltage "Between channel and ground" is "+/- 60 V", not "60 Vp-p", which are not that same thing regardless of language.

author: bostonman
author_rank: Super Contributor
timestamp: October 10, 2025, 02:03:48 pm
content: QuoteI feel better then because I thought it was just my overthinking.I want to measure voltages that might be close to 60Vp, but will probably avoid it now.
Confusion about the footprint of USB-C connector - Page 1
Forum section: electronics / projects

author: Blackgar
author_rank: Contributor
timestamp: May 04, 2025, 06:48:38 am
content: I am going to use the 10172013-00011 from Amphenol and there is a mismatch on their site (https://www.amphenol-cs.com/product/1017201300011lf.html)The Product Drawing has the below signals in row:DN_2DP_1DN_1DP_2On the bottom of their site, its the ready-to-download footprint with the below signals in row:DP_2DP_1DN_1DN_2I am not sure which one of those 2 sources to trust, they both are on their official site..

author: moffy
author_rank: Super Contributor
timestamp: May 04, 2025, 07:20:03 am
content: Quote from: Blackgar on May 04, 2025, 06:48:38 amI have a PCB I made with a very similar Amphenol USB-C connector and it is:DN_2DP_1DN_1DP_2
Confusion around SMPS Buck controller current sense pins and FCCM enable - Page 1
Forum section: electronics / projects

author: Jovan1
author_rank: Newbie
timestamp: May 05, 2022, 05:34:28 pm
content: Well hi, I've ran into a confusing detail in a reference design schematic of a 3-Phase SMPS Buck controller, specifically, CSN and CSP seem to be wired in the correct polarity on phase 1 and 2 but flipped around on phase 3. Could this be intentional? Mistake in pin labeling? Or does the polarity not matter at all? Second, the controller has a SKIP# pin to get the power stages into FCCM mode, Forced CCM, used to force CCM mode even when in light load conditions, where DCM would be more conventional. The power stages that i am including in my design do not have such an input as the ones in the reference schematic do, would i run into any major issues if i simply leave the SKIP#/FCCM output of the controller unconnected? I hope to get some useful insight from anyone knowledgeable around this topic

author: wraper
author_rank: Unknown
timestamp: May 05, 2022, 05:41:26 pm
content: Imho it's an error in schematic which is easy to make due ordering of CSP and CSN pins and similar names.

author: wraper
author_rank: Unknown
timestamp: May 05, 2022, 07:47:42 pm
content: QuoteBTW they are connected properly on phase 1 and 3, and flipped around on phase 2.

author: Jovan1
author_rank: Newbie
timestamp: May 06, 2022, 03:18:03 am
content: Yeah, oops, thanks for pointing that out, im editing the post so its corrected. About your first reply, yeah i thought it might be a mistake, thanks for the input
Confusion on using ESP32-S3 ADC - Page 1
Forum section: electronics / projects

author: robzy
author_rank: Regular Contributor
timestamp: September 06, 2024, 08:52:06 am
content: I want to use the ESP32-S3 ADC which proudly boasts that it can do 100ksp but I can't seem to work out how to practically use that because of bandwidth limitations.The docs say you should ideally connect a 100nF ceramic capacitor to the ADC pin (source).However, its also well known that the ADC pins will glitch low for 60uS on startup (source).That low glitch would require an impedance of roughly 500ohms to avoid a significant over-current situations.But an impedance of roughly 500ohms would make a low-pass filter with the 100nF capacitor for a bandwidth of roughly 3kHz.What gives? Can I drop the capacitor to get more bandwidth at the expense of noise?

author: Smokey
author_rank: Super Contributor
timestamp: September 06, 2024, 09:03:54 am
content: At least there isn't a 0-250mV dead zone like in the original ESP32 ADC. Who knows how that ended up being the case. So they have a history of crappy ADCs.The plot shows a decrease in noise between no cap and 100nF. Interpolate between those and pick a cap that works with your series resistance maybe?https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/peripherals/adc_calibration.htmlYou could also buffer the ADC with an opamp that has an enable pin.

author: robzy
author_rank: Regular Contributor
timestamp: September 06, 2024, 11:24:46 am
content: Thank you for confirming that I'm not losing my mind.Its great that it has an ADC, but it definitely doesn't give practical 100ksps performance.I'll drop an MCP3201 SPI ADC in there and be done with it. Should be able to do 50ksps easy with 3.3V.
Confusion over Opamp Hysteresis equation in Linear AN - Page 1
Forum section: electronics / projects

author: bitbanger
author_rank: Regular Contributor
timestamp: January 16, 2018, 02:31:14 am
content: Hi - can anyone explain what the Vo_max parameter is in the below Linear Tech app note" ("Design Ideas")?I back calculated it to be 5.34V based on 92mV hysteresis in the example given. The author states"Vo_max = maximum output swing (high) of U1 at VBATT is equal to the lockout voltage". The English is a little goofy in this statement, but it sounds like they're saying the maximum U1 output during lockout is 5.34V. However the rail is limited to Vbatt (3.0V at lockout), so what gives?http://cds.linear.com/docs/en/lt-journal/LT1389_0699_Mag.pdfThanks for your thoughts + time!Best,Jamie

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 16, 2018, 03:34:15 am
content: It says that VOMAX = maximum output swing (high) of U1 at VBATT is equal to the lockout voltageThat would be about 3 volts--"The circuit is set up for a single-cell Li-Ion battery, where the lockout voltage—the voltage when the protection circuit disconnects the load from the battery— is 3.0V."I did an independent analysis of the circuit and concur about the 92mV hysteresis.Does this answer you question???

author: bitbanger
author_rank: Regular Contributor
timestamp: January 16, 2018, 03:46:13 am
content: I agree on all points, however if you use VOMAX=3.0V, the hysteresis comes out to be 50.2mV, not 92?

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 16, 2018, 03:51:10 am
content: Quote from: bitbanger on January 16, 2018, 03:46:13 amI did not check their equations. Here is my analysis. It is pretty shorthand but may be understandable.

author: bitbanger
author_rank: Regular Contributor
timestamp: January 16, 2018, 04:10:36 am
content: Sorta - I follow the superposition to find dVB in the first image.Unsure what the dVbatt is, and are you saying dVA is necessarily = to dVB = 41mV (because they are +/- terminals of the opamp)?Many thanks for the explanation!

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 16, 2018, 02:11:33 pm
content: dVbatt is the change in Vbatt to compensate for the change in Va. My analysis ignores the fact that dVbatt also changes the voltage at Va, but it is a good approximation since the sensitivity of Vb to VBatt is much higher than the sensitivity of Va to Vbatt.--Looking back I see that I said "higher" when I should have said "lower"--

author: bitbanger
author_rank: Regular Contributor
timestamp: January 17, 2018, 02:58:37 am
content: Got it, thank you!

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 17, 2018, 03:10:01 am
content: Note that I noticed a mistake in my last comment (and entered a correction). But I think you probably figured it out.

author: bitbanger
author_rank: Regular Contributor
timestamp: January 17, 2018, 03:12:46 am
content: Yeah my hangup was not initially realizing dVbatt was the hysteresis. Thanks gain.
Connect with TV remote - Page 1
Forum section: electronics / projects

author: say2paul
author_rank: Contributor
timestamp: April 25, 2014, 11:53:45 am
content: While we open up any TV remote, we can clearly see carbon buttons on the rubber keypad and next to it is the circuitry.How to connect Arduino/Micro-controller IO pins with remote control circuit?

author: Psi
author_rank: Super Contributor
timestamp: April 25, 2014, 12:24:02 pm
content: It's often a matrix, so you cant easily connect it directly to an Arduino/MCUThe easiest solution is to use a small 5v relay.You can drive the relay from the Arduino and use the relay coil to short the two button tracks on the remotes PCB.

author: say2paul
author_rank: Contributor
timestamp: April 25, 2014, 12:28:24 pm
content: Quote from: Psi on April 25, 2014, 12:24:02 pmThanks dear, so one relay is sufficient for this?And one more thing.. I can see the connector on one side only and there is no way I can solder them.

author: David_AVD
author_rank: Super Contributor
timestamp: April 25, 2014, 09:45:51 pm
content: Try tracing the connections back and solder to the chip. That's what I did years ago.

author: pickle9000
author_rank: Super Contributor
timestamp: April 25, 2014, 10:19:07 pm
content: 4066

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 25, 2014, 10:26:59 pm
content: Quote from: say2paul on April 25, 2014, 11:53:45 amWHY do you think you want to tap into the remote control circuitry?The much more modern (and easy) method is to discover (by simple observation) what Infra-Red code the remote puts out, and use an 89-cent IR LED to simulate the signals.Yes, another method is to use a 4066 chip for each four buttons you want to "emulate". Connect one of the 4066 "switches" across EACH and every button pad pattern.Then by turning on each transistor switch, you simulate a single button-press. But people have not done this for decades because the IR LED method is so much easier and better.
Connect your ISA cards on a modern motherboard with TPM module - Page 1
Forum section: electronics / projects

author: DC1MC
author_rank: Super Contributor
timestamp: March 24, 2023, 07:00:38 pm
content: https://www.hackster.io/news/andy-rasteri-tait-brings-isa-back-with-a-bang-by-abusing-the-tpm-slot-on-modern-motherboards-9dac2cf3162a

author: coromonadalix
author_rank: Super Contributor
timestamp: March 24, 2023, 07:07:38 pm
content: WUUUUUUTwow

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 24, 2023, 08:59:28 pm
content: Relatively useless, but fun.

author: Tony_G
author_rank: Super Contributor
timestamp: March 25, 2023, 12:08:10 am
content: Hmmm - I currently have a DolchPac that I worked up to provide me the ability to run some old HP software that expects a specific ISA HPIB card to be in the machine - It'd be interesting to see if I could use a way smaller industrial PC to run that stuff on occasions when I need to.Thanks for highlighting it.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 25, 2023, 03:00:48 am
content: there is or was someusb to isa adapterspci to isa adaptersSome old hp gear had this pci to isa bridge chip cant remember the part number, i think i have an pci to isa board somewhere loll

author: edpalmer42
author_rank: Super Contributor
timestamp: March 25, 2023, 05:19:03 pm
content: Even if this card solves the hardware side, you still need drivers. Note that the original article specified that the Sound Blaster was running under DOS. The closest thing to 'useful' would be if it worked in a VM.

author: m k
author_rank: Super Contributor
timestamp: March 25, 2023, 08:09:41 pm
content: Yes, i/o commands are the key.With real thing it goes straight through, but with newer systems there will be an exception, so something must be present and handle that exception.Finally exact i/o command is executed but before that the security level must change to correct level and address of the command reroute through the new hardware.With straight through software it would be less than extremely painful to change all i/o commands directly to memory mapped things that new hardware can understand and new system accepts without any exceptions, but all kind of scrambling styles of old times will most likely drop that less than part off the table.
Connectable terminal blocks vs vibration? - Page 1
Forum section: electronics / projects

author: Mad ID
author_rank: Regular Contributor
timestamp: February 11, 2014, 04:11:04 pm
content: Hi,in my current project I'm using connectable 3.5mm terminal blocks like the one in the picture:http://www.sauro.net/img/pro/sch/CTF00T.jpgSince the electronic module will be mounted on the truck, I'm worried that screws that hold the cable wires can get loose?Does anyone have experience with vehicle electronics and this type of connectors?BTW cables will not have any force on them as they go though cable glands couple of centimeters away.Thanks.

author: alank2
author_rank: Super Contributor
timestamp: February 11, 2014, 04:23:12 pm
content: I may be wrong here, but I would think the "spring tension" placed on the screw by it pressing into the wire would hold the screw from vibrating too much like a lock washer might. This is a guess. I suppose it depends on how much vibration.Have you seen the push button terminal blocks? I use these quite a bit because they are easier.

author: pickle9000
author_rank: Super Contributor
timestamp: February 11, 2014, 05:00:31 pm
content: As a general rule on heavy equipment the connector should have some sort of clip, screw or be caged to keep it in place. If your item is being mounted in a box high density foam or rubber block on the top of the connector (between the connector top and box wall) will cage it.

author: fcb
author_rank: Super Contributor
timestamp: February 11, 2014, 05:02:53 pm
content: If your going to use that type of connector, I suggest the 'cage-clamp' variant, no screw to loosen.

author: jmaja
author_rank: Frequent Contributor
timestamp: February 11, 2014, 05:21:16 pm
content: Quote from: Mad ID on February 11, 2014, 04:11:04 pmI'm using the same terminal blocks and its just on its way to vibration test (mainly intended to see that all components stay on the PCB). I'm not worried about the screws. They need to be quite tight in order to keep the wires in place and screw terminals are common in automotive use. I was a bit worried about the whole connector keeping in place, but it seems to have quite high clamping force, at least for the 8 wire connector. Interesting to see what happens in the test!

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: February 12, 2014, 05:31:58 am
content: Quote from: jmaja on February 11, 2014, 05:21:16 pmCan you link in some information about the test company or procedure?
Connecting 3.6v white led to 6v power supply - Page 1
Forum section: electronics / projects

author: Stefg023
author_rank: Newbie
timestamp: February 12, 2014, 04:59:04 am
content: Trying to power up one white led, 3.6v off 6v power supply. Understand what resistor I need.What's throwing me off is this microchip looking thing inside the project I'm copying. The difference is, on the original project, there's a 4 hour timer on it. So, is this microchip used for that? Or does it have another purpose?I don't need a timer for my project, just on/off option.Let me just add I'm a newbie to electronics.Thanks!

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 12, 2014, 05:09:58 am
content: Assuming it's a standard 20mA LED, use a 120 ohm resistor. 150 ohm works too and is more common. If you're using it as an indicator and it's too bright, keep using larger resistors until it's just right. (It would probably end up in a few kiloohms to a few tens of kiloohms.)

author: Stefg023
author_rank: Newbie
timestamp: February 12, 2014, 05:12:06 am
content: Thanks.Do you know if I need this microchip/circuit board thing that I'm seeing?

author: sleemanj
author_rank: Super Contributor
timestamp: February 12, 2014, 05:13:22 am
content: Quote from: Stefg023 on February 12, 2014, 04:59:04 amMy telepathic powers are unfortunately lacking, so as you haven't shown us the circuit, I really couldn't say.

author: Stefg023
author_rank: Newbie
timestamp: February 12, 2014, 05:16:34 am
content: I tried and it said it was too big! Trying again...

author: sleemanj
author_rank: Super Contributor
timestamp: February 12, 2014, 05:19:02 am
content: Quote from: Stefg023 on February 12, 2014, 05:16:34 amYes the silicon die under the blob is undoubtabley the timer.If you don't need the timer;+6v -> [Suitable Resistor] -> [LED(s)] -> Gnd

author: Stefg023
author_rank: Newbie
timestamp: February 12, 2014, 05:24:46 am
content: Thanks! That's what I wanted to hear.

author: mariush
author_rank: Super Contributor
timestamp: February 12, 2014, 06:37:27 am
content: Voltage = Current x Resistor (Ohm's law)Voltage = Input voltage - Forward Voltage LED x Number of Ledsso in your case => Resistor = (Input Voltage - Forward Voltage ) / CurrentFor 20 mA (0.02A), you have R = (6-3.6) / 0.02 = 2.4/0.02 = 120 ohmIf you want less current therefore less brightness, you can increase the resistor value.
Connecting a cmos oscillator to chip - Page 1
Forum section: electronics / projects

author: Tekelec
author_rank: Newbie
timestamp: November 14, 2022, 12:06:42 pm
content: HiI have a cmos 12mhz oscillator part number LFSPXO020465 which I'm using as an external clock for a DAC project.I'm having an issue where unless I install a series resistor between the oscillator output and the DAC chip (ms8416t) then after a few hours it kills the DAC. I have scoped the oscillator voltage and is around 90% a vcc at peak as expected. Installing the resistor saves the chip but also affects the wave form, that is it changes from a square wave to a triangle.My question is should the oscillator be coupled via a capacitor or a resistor to the IC?

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2022, 05:11:03 pm
content: It's possible for reflections in an unmatched line to cause higher voltage spikes.How close is the oscillator to the chip? Did you measure the actual voltage going to the chip? Bear in mind the oscilloscope probe can load it down.What value resistor did you use? Which end was the resistor connected? You could try a 100R resistor in series with 47pF, between the clock and 0V, right next to the chip, to provide a load for the higher frequency elements of the signal.
Connecting a separate-port BMS as a common-port - Page 1
Forum section: electronics / projects

author: Fallingwater
author_rank: Contributor
timestamp: September 29, 2022, 10:40:02 am
content: I'm reusing a separate-port BMS for a 10S battery. It has contacts for B-, C-, P- (it doesn't require main B+ to be wired to it; the only B+ is on the balancing connector). I understand that C means "charge" and P means "power", or where you tap it for the main output.Thing is, I have no need for an extra charge lead since this is going to be a range-booster battery for an e-scooter, and will be paralleled to the main battery. I therefore want to wire it common-port.I know the BMS will let charge in if it comes from the main lead, because it was taken out of a different e-scooter and therefore must allow for that in order for e-braking to work, but will it balance?Or do they let energy in the battery from the main lead, but need actual charging current to come from the charge contact in order to balance?I unfortunately can't provide technical details on the BMS itself as the markings got deleted while salvaging it; needless to say, I've no idea who the manufacturer is - but I doubt I'd know anyway, since it's a generic type as seen in umpteen Chinese batteries in cheap scooters.

author: nctnico
author_rank: Super Contributor
timestamp: September 29, 2022, 12:12:06 pm
content: Short answer: you can't. The load port likely isn't protected against overcharging so this would create a very dangerous situation when the battery is connected to a charger through the load port.

author: Fallingwater
author_rank: Contributor
timestamp: September 29, 2022, 01:11:34 pm
content: The charger is current- and voltage-limited and isn't a dangerous point in this setup. In fact, I set it (via internal potentiometer) to charge at a bit less than full voltage to help the battery stay healthy longer.Edit: I believe it does actually protect against overcharging through the P port, from its nature as a PEV unit that must support regen braking - otherwise you'd risk damaging the battery every time you hit the brakes. In any case, I'll have a voltmeter permanently connected warning me of any dangerous voltages.All I want to know if the BMS balances when charging through the load port.
Connecting a washing machine water level sensor to a microcontroller - Page 1
Forum section: electronics / projects

author: dinushka95
author_rank: Newbie
timestamp: March 23, 2015, 05:19:46 am
content: Helloi am trying to connect this water level sensor from a washing machine to microcontroller.when the water level increase the pressure inside the sensor increase causing a ferrite to move-up inside a coil.the pins on the 2 side are connected to the coil and 2 capacitors are connected from them to the middle pin. i think the middle pin is the sense line.P.S - a label on the sensor says 5v DC1) how it works (capacitance or resistance)?2) how to connected it to a microcontroller?

author: mikerj
author_rank: Super Contributor
timestamp: March 23, 2015, 08:12:26 am
content: It works by changing the coupling between the two halves of the coil. This looks like a half bridge LVDT orLinear Variable Differential Transformer.

author: SeanB
author_rank: Super Contributor
timestamp: March 23, 2015, 06:52:14 pm
content: Refer to the attached page 30. The water level sensor is used as a LC oscillator, and the frequency is measured by the MCU. Easy to build the oscillator using a 4069 hex buffer.

author: dinushka95
author_rank: Newbie
timestamp: March 24, 2015, 01:10:06 am
content: thank you... very much....

author: aargee
author_rank: Frequent Contributor
timestamp: March 24, 2015, 04:49:38 am
content: It's always good to try to analyze and understand the circuits that you remove parts from before you strip salvage parts from a board, it saves lots of headaches about 'how the hell did that work/interface/etc'. Even helps you to ID MOVs and capacitors as like for like when their writing is sooo darn small/feint/uninterpretable.No that you salvaged the sensor in this case, of course. The Fisher and Paykel washing machine we have uses that very technique and I think uses a 4096 as the oscillator as well.
Connecting  Audio USB  controller  in  VL812   USB 3 HUB - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: May 31, 2017, 07:17:49 am
content: Hello,Currently I am working in VL812 USB 3.0 Hub Controller (B1),http://www.datasheetspdf.com/datasheet/VL812.html.My project plan is to connect an audio usb controller (PCM2912A) with it,http://www.ti.com/lit/ds/symlink/pcm2912a.pdf.Let me know what difficulties can arise.Thanks in advance.RegardsHasan
Connecting Battery Charger Interface Pins to a PCB (Horizontally) - Page 1
Forum section: electronics / projects

author: MixedSignalSystems
author_rank: Contributor
timestamp: August 30, 2016, 05:25:23 am
content: I've been stumped on something that I thought would be quite simple and could do with a little help please. Its always the simple things that trip you up!I'm working on a small portable device with a LiPo battery. I'd like to place battery charger interface pins at the "bottom" of the device, similar to the majority of mobile phones. With that in mind, the long axis of the charger interface pins will run parallel to the PCB rather than perpendicular to it.I'm looking for a way to connect the two charger interface pins to the PCB in a cheap and area efficient manner.I noticed on an iFixit Teardown of the Fitbit Flex that the Fitbit guys seem to have done this in quite a good way.https://www.ifixit.com/Teardown/Fitbit+Flex+Teardown/16050In the two images below (credit to iFixit for these), you can see how they have done it. In this case, the 3 charging pins are connected to the PCB through 3 surface mount "brackets"/"clips"/"holders"/"clamps"/"tabs"/"receptacles"/"grippers".To me, this looks like a very simple solution (assuming you can ensure that the PCB will stay in place when installed).My problem is that I can't seem to source the appropriate surface mount components to pair with the pins. Its beginning to drive me mad. I assume that they are out there somewhere but I haven't been able to find them on Digikey, Mouser, etc. I've come close with SMD fuse holders and terminal blocks and a few pogo pin target devices but the fuse holders and terminal blocks are too large and the pogo pin target devices are overkill (in terms of performance and associated cost).These just need to handle 50mA DC to charge a small LiPo battery. I must have a blind spot for these. I can build up my own if I need to but at this stage, I'd like to know where to find them ... and what to call themI'd really appreciate any help in sourcing these or any other suggestions for implementing this.Many thanks,Kieran
Connecting commercial coffee machine electric board with raspberry pi - Page 1
Forum section: electronics / projects

author: Mr.G
author_rank: Newbie
timestamp: October 13, 2019, 11:56:04 pm
content: I have been trying to connect our commercial coffee machine with raspberry pi 3b +. As far as I have been told every coffee machine board has different board and should have different way of connecting, I am not getting relevant answer. Does anyone has tried connecting coffee machine board with raspberry pi . If yes what method did you applied .. plz helpThe link below will give some information on electric board of the coffee machinehttps://www.wegausaparts.com/my-concept

author: BradC
author_rank: Super Contributor
timestamp: October 14, 2019, 01:49:11 am
content: Quote from: Mr.G on October 13, 2019, 11:56:04 pmMy I Ching calculator says "a suffusion of yellow".How about some more info, like perhaps the make/model of Coffee machine as a start.

author: beanflying
author_rank: Super Contributor
timestamp: October 14, 2019, 04:18:33 am
content: The obvious question is WHY? Is there an issue with your current board?If not what are you trying to improve/modify or control the WEGA brain doesn't? If you are wanting to try and tighten up the brew temperature range for example then an electrical only solution is not it. Tuning of HX loops in conjunction with say a PID is black magic to get an 'improvement' and playing with orifice plates to adjust flow is as much or more important.Even then this 'improvement' is driven by the Beans used, how they are treated and the mug on the knobs skills and the tastebuds of those drinking it.
Connecting different instruments together with different ground references - Page 1
Forum section: electronics / projects

author: RawCode
author_rank: Regular Contributor
timestamp: December 25, 2022, 04:39:22 pm
content: Hello everyone, happy holidays and happy new yearI would like to ask you a question.I wanted to design an instrumentation that interfaces with other instruments via shielded cables. All of this instruments, mine included, share the same power supply.Each instrument is powered by a standard single supply 12 V DC, where each instrument consider the negative terminal as reference ground for the signals.These instruments usually are interconnected via shielded cable, carring audio-like signals (1 Hz - 15 kHz), and each side of the cable's shield is connected to the ground reference.Also the metal chassis is connected to the ground reference.This is a quick sketch of the system. My device is in the middle:The instrumentation that I would like to desing needs a split DC supply, so I was considering a DC splitter like the one in the attached picture.I don't need a lot of power, so I think this solution could work for me.The problem is that I'm worried that once I make a connection between two instruments, since they have different ground reference and also considering that I'm using a virtual ground, they can behave differently or even cause some damages.I could use a signal transformer, but ther are expensive, bulky, and also can cut part of the signals. I need the smallest (and cheapest) solution as possible.Do you have any suggestions?Thanks

author: wasedadoc
author_rank: Super Contributor
timestamp: December 25, 2022, 05:00:31 pm
content: Probably you are already 99% sure that what you propose will not work but are hoping for the 1% chance that you are wrong!Why does you instrument need + and - supplies about ground? Even 1Hz can be AC coupled with a suitably large capacitor followed by a high impedance.Otherwise you could use an isolated dc-dc converter or two so that the 0 Volt point of the + and - 6 volt rails of your instrument can be connected without issue to grounds of the other equipment.

author: RawCode
author_rank: Regular Contributor
timestamp: December 25, 2022, 05:44:04 pm
content: Thanks for the replyQuote from: wasedadoc on December 25, 2022, 05:00:31 pmYeah probably ahahahQuote from: wasedadoc on December 25, 2022, 05:00:31 pmThe instrument treat the incoming signal exploiting a circuitry that is more precise and reliable with a split supply instead of using a single dc supply and a dc bias.Quote from: wasedadoc on December 25, 2022, 05:00:31 pmI was thinking to use a TC1044S which is cheap, requires few components, and using the boost pin the switching frequency will set above the frequency range that I need, obtaining +/- 12V instead of +/- 6V.The circuit will have the negative terminal of the DC supply as the ground reference as all other instruments, which is nice and avoids any complications.The thing that bothers me is a switching power supply in a linear circuit: I'm worried about the noise
Connecting female sockets to veroboard  pins - Page 1
Forum section: electronics / projects

author: richard1991
author_rank: Contributor
timestamp: May 10, 2017, 10:59:57 am
content: Hi. I've used veroboard pins on a veroboard so I can connect flying leads or jumper wires. I went and ordered some breadboard jumper wires with female sockets on the end, but they do not fit the 1mm diameter veroboard pins. So, I need some jumper leads with female sockets that fit the 1mm diameter pins.Is anyone here buying such a product, or identified a supplier? I've not turned up anything so far. Thanks.

author: tooki
author_rank: Super Contributor
timestamp: May 10, 2017, 04:34:45 pm
content: Seehttps://www.eevblog.com/forum/projects/please-identify-this-connector/In there, I have pix and a manufacturer link, might be what you're looking for.
Connecting output of class D amplifier to laptop line in. - Page 1
Forum section: electronics / projects

author: tapasxplore
author_rank: Contributor
timestamp: November 06, 2017, 08:14:55 pm
content: Hi,I am making a audio project in which, I am amplifying sound using class D audio amplifier TPA2005D1 from TI the output is driving the speaker well. I want to know that can I connect PWM output directly to microphone line input in my laptop, or I have to use Class AB amplifier then only I can connect to line input of my laptop.Regards,Tapas

author: capt bullshot
author_rank: Super Contributor
timestamp: November 06, 2017, 08:51:19 pm
content: No you can't directly connect the amp's output to a mic input, no matter if it is a AB or D amp.The TPA2005 has a BTL output, so you need a differential to single ended conversion, filtering to remove the PWM and proper attenuation to bring the signal level down to mic input level.With the AB amp, you can skip the filtering, if you need a diff amp depends on the AB amp (if it is single ended or BTL), then you also need the attenuator.Last but not least, you need AC coupling into the Mic input, since these often place a bias voltage for electret mike capsules on the input.If you happen to have a real line input on your laptop, you'll still need the attenuator since the amp's output level is larger than line input level. Mic input level is even lower than line input level.

author: fourtytwo42
author_rank: Super Contributor
timestamp: November 06, 2017, 08:53:20 pm
content: Well its 250Khz filterless from an H-bridge so neither of the speaker terminals are ground referenced. The good news its only 5V never the less considerable attinuation is a good idea and AC coupling to avoid any microphone voltage upsetting the class-D. I would experiment but you might get an awful noise!
Connecting positive supply to power plane - Page 1
Forum section: electronics / projects

author: tapasxplore
author_rank: Contributor
timestamp: March 20, 2018, 04:58:07 am
content: I am making a four layer PCB. The top and bottom layer are signal and the internal layer has power and ground layer.L1 --- Signal,L2 --- Power,L3 --- Ground,L4 --- SignalI am using Li-ion battery and then using LDO to convert it to 3V. 3V is then powering the whole circuit. Should L2 should be connected to 3V LDO output or Li-ion battery positive output. Both are positive supply source, I am unable to decide should I connect LDO 3V output or Li-ion output to the power plane.Regards,

author: killcode
author_rank: Contributor
timestamp: March 20, 2018, 05:20:23 am
content: Consider the purpose of a power plane....If Vbat is only provided to the LDO and the output of the LDO is distributed to all other components, then it doesn't make sense to connect the plane to Vbat does it?

author: bson
author_rank: Unknown
timestamp: March 21, 2018, 02:05:20 am
content: Connect it to the rail, i.e. the LDO output.Consider swapping your power and ground planes so they're L3 and L2 respectively. Most signals end up on the top layer, because that's where most parts are, and the ground plane typically has lower impedance than the power. With ground in L2 it makes it super easy to put ground right under an XO, oscillator, reference clock network, or elsewhere where you think it might be beneficial - in fact, this is what just happens unless you go out of your way. Parts on the bottom often end up being decoupling and pull resistors, that connect to the power plane. Or card/battery holders, connectors, that kind of thing - maybe the occasional part that just didn't fit on top. Then, in the future, if you use blind vias you'll save substantial board real estate with this stackup. You'll develop habits and practices based on your stackup, and it's nice to immediately realize a gain if you do decide to pony up for blind vias. (Not much use for buried vias with either of these 4L stackups.)

author: soubitos
author_rank: Frequent Contributor
timestamp: March 21, 2018, 03:05:10 am
content: You might want to take into account the low but present voltage drop of the LDO you have chosen.Your Li-Ion might be powering your pcb only down to 3.6-3.3V at best. This means you loose maybe up to 30-40% of its capacity. You might want to search for a buck-boost switching or something similar available
connecting RF and biasing PCB's together X-microwave - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: September 14, 2025, 11:31:27 am
content: Hello,I have a question regarding a variable attenuator .Generally we plug the biasing network to the RF component using spring pins.As you can see in the photo below there is no sping pin present. so how do i need to connect the two PCB's threw the proto plate?Thanks.RF component:https://catalog.quanticxmw.com/item/attenuators/voltage-variable-attenuators/xm-b6h5-0404dBiasing network:https://catalog.quanticxmw.com/item/bias-and-control/voltage-regulators/xm-b1x6-0404d
Connecting separate charging/discharging wires to common port BMS - Page 1
Forum section: electronics / projects

author: hpapagaj
author_rank: Contributor
timestamp: January 05, 2024, 10:57:31 am
content: Hi!I am upgrading my ebike's BMS, but the BMS I want has common port for charging and discharging. My old BMS was a separate port dummy BMS.Can I connect existing separate wires (load and charging) to the common port of the BMS? I think it could work, but I want to be 100% sure.
Connecting Sim800 speaker and Mic to UDA1380 Codec - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: July 11, 2017, 08:25:23 am
content: Hi,I just wanted to use a single microphone with the MIC input of UDA1380 and connect the UDA1380 line out to the SIM800 MIC input, also I wanted to connect the SPK output of the SIM800 as line input of UDA1380, because I wanted to be able to record and play back good quality sound from a SD card, I just wanted to connect them some how directly, Am I doing it right?Here is some parts of the schematic