hybridfree/eevblog-posts huggingface dataset:
Could you help me understand this optical encoder Datasheet? - Page 1
Forum section: electronics / beginners

author: Blitzschnitzel
author_rank: Regular Contributor
timestamp: September 19, 2019, 09:54:23 pm
content: So, I want to order this quite pricy optical encoder:https://static6.arrow.com/aropdfconversion/b37bee95f5eae7e7f00cc37d7f45757e265dbb6b/50924574275363em14.pdfIf I understand it correctly there is an IR LED inside and two Photodiodes. When light passes through the slotted wheel, the diode becomes conductive.What I don’t understand is where the Diode connects to. VCC or ground? The schematic in the Datasheet just shows an unhelpful box. On the first page it says output voltage 4v. Does that mean the signal pins either float or forward VCC minus a bit?

author: ataradov
author_rank: Super Contributor
timestamp: September 19, 2019, 10:10:59 pm
content: There is internal circuit that creates a voltage output. The voltage will be 0-0.8V indicating logical low and 4.0-5V indicating logical high.

author: ledtester
author_rank: Super Contributor
timestamp: September 19, 2019, 10:47:36 pm
content: QuoteIt is more likely that phototransistors are being used for the two channels:https://www.rohm.com/electronics-basics/photointerrupters/what-is-a-photointerrupterWithout a pull-up resistor the output of a channel would be either 0V or floating. Since the datasheet describes the output as either LO or HIGH and doesn't show that pull-up resistors are needed my guess is the device has its own pull-ups.

author: Blitzschnitzel
author_rank: Regular Contributor
timestamp: September 19, 2019, 11:33:18 pm
content: Ah, Thank you very much! I want to connect the encoder to an atmega 32U4 And the IO pins state low up to 0.9v. That’s very close to the 0.8v. Should I put two resistors in series with the signal pins to reduce the voltage a bit? I am not sure about the value though if I want to reduce by, let's say, 0.5v because there is supply current and output current. Does supply current already include output current?

author: ledtester
author_rank: Super Contributor
timestamp: September 19, 2019, 11:42:25 pm
content: The datasheet says the 800 mV LOW signal is a maximum, so I wouldn't worry about it. In practice I would expect the LOW voltage to be a lot lower than that.

author: ataradov
author_rank: Super Contributor
timestamp: September 19, 2019, 11:42:40 pm
content: No, don't worry about it, just connect it directly to Arduino and you will be fine.

author: ledtester
author_rank: Super Contributor
timestamp: September 19, 2019, 11:46:12 pm
content: Quote from: ataradov on September 19, 2019, 11:42:40 pmYes - after all the datasheet states: "HCMOS, CMOS and TTL compatible" so no special interfacing is necessary.

author: Blitzschnitzel
author_rank: Regular Contributor
timestamp: September 19, 2019, 11:53:25 pm
content: OK. Thank you very much.
Could you identify this component? - Page 1
Forum section: electronics / beginners

author: Mo3tasm
author_rank: Contributor
timestamp: September 20, 2016, 10:53:14 am
content: I have this weird looking component attached to the positive terminal of a sealed lead acid battery,Could you please help me identify it, what is it? and what is it for?

author: paulhm81
author_rank: Regular Contributor
timestamp: September 20, 2016, 11:21:30 am
content: looks to me like a polyfuse but i'm not sure!

author: Mo3tasm
author_rank: Contributor
timestamp: September 20, 2016, 11:34:11 am
content: Yeah that's probably it,I also looked for resettable fuse packages and they look somewhat similar.Thanks..

author: rjardina
author_rank: Contributor
timestamp: September 20, 2016, 11:54:59 am
content: Bi-Metal switch?
Could you please benchmark the Linux at25 driver writing to SPI EEPROM? - Page 1
Forum section: electronics / beginners

author: SlowBro
author_rank: Regular Contributor
timestamp: January 29, 2018, 02:53:58 pm
content: Does you have an SPI EEPROM handy? Would you please benchmark writing a largeish amount of data to it using theLinux at25 kernel driver? (Source code.)I'm interested to know about the speed writing data larger than the page size, but I don't have one of these chips handy. So if the page size is 128 bytes, I'd like to know what the write speed is for say 256 bytes (or larger). Please share the time to write, the data size, the EEPROM type, and the SPI speed.
Couldn't an externally saturated choke be used to rectify AC? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: June 24, 2023, 09:52:52 pm
content: If I get a high inductance choke and saturate it externally with a magnet, then feed AC trough it, wouldn't the output be somewhat half-wave rectified since in one wave the core would be saturated and pass the current trough the winding, but on the other wave the current would be much lower because of the inductance of the choke.

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 24, 2023, 10:02:21 pm
content: Wouldn't the other wave de-saturate it and screw the next cycle up so in the end it would be a weird asymmetric choke?Wouldn't the magnetic fields opposing the magnet create huge currents, wasting a lot of power?ñ(yes I suck at magnetics)

author: Gyro
author_rank: Super Contributor
timestamp: June 24, 2023, 10:03:12 pm
content: Look up 'magnetic amplifiers', basically the same thing but passing a DC current through an auxiliary winding. It's difficult to get a high inductance AC choke without a closed laminated core, so it wouldn't be susceptible enough to external permanent magnetic fields.
Couldn't find these SMD codes - Page 1
Forum section: electronics / beginners

author: RoGeorge
author_rank: Super Contributor
timestamp: August 18, 2025, 06:25:06 am
content: Anybody knows what are these, please?(The green plastic ruler is in millimeters.)Please note the big one has 14pins, so I guess it can not be an SG3525 PWM controller (16pins). No PCB pics, they were in a ziplock bag together with a few other tantalum and a couple of small ferrite pot SMDs, so they might be SMPS parts, but they can be anything else just as well.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 18, 2025, 11:06:43 am
content: Soldered the smallest one out of curiosity. It's an individual NOT gate, CMOS, TC7S04F, like this:https://toshiba.semicon-storage.com/info/TC7S04F_datasheet_en_20170801.pdfApparently, the dot in the middle of the "E.5" has to be skipped.If so, then the chip can be found as one of the options corresponding to "E5" inhttps://smd.yooneed.one/code4535.htmlIsn't there a dot between E and 5, in the pic? Why that one does not count?Or is the missing dot just a fluke in that particular SMD database linked above?
Counter Circuit Troubleshooting - Page 1
Forum section: electronics / beginners

author: infernowheels
author_rank: Newbie
timestamp: March 29, 2015, 08:58:48 am
content: Hey guys, so we were asked to follow this circuit design:https://app.box.com/s/nuqszc1dts3sm6l9hoi2noud6704eicvNow I've followed the given paper to me as best as I could but I still have 2 problems withmy design right now:>When it's powered on, the ones digit counter has to start from zero instead of one>The circuit has to reset after it reaches 60.Check this video for reference and feel free to point out any more problems~https://youtu.be/sYe8vIriKaoSome pictures of what I made:

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 29, 2015, 04:15:03 pm
content: I don't see any bypass caps, anywhere. If it runs smoothly at all, I'll be surprised!Typically you need a 0.1uF ceramic for each chip, VCC to GND.So, you need to add a conditional reset state? Have you covered AND/OR gates or digital comparators yet?Tim
Counter counter counter, type to bye? - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: May 08, 2018, 08:11:59 pm
content: I would like to bye a good <500$ counter that can count different events not just Hz, but do not know what too look for, question to ask and so on.On top of that, it looks like there are many types?frequency countermultifunction counteruniversal countermultifunction frequency counteruniversal frequency counterHeeelp :-)

author: David Hess
author_rank: Super Contributor
timestamp: May 08, 2018, 09:35:30 pm
content: It is not real clear what your requirements are but I think the best low cost option for general purpose use is a used HP5315 or HP5316 universal frequency counter.
Counting Pulses Using Interupts - Teensy 3.6 - Page 1
Forum section: electronics / beginners

author: threephase03
author_rank: Contributor
timestamp: July 26, 2018, 11:50:27 pm
content: Hi all.I'm trying to count pulses using interrupts on the Teensy 3.6. I can count 430000 pulses in 30s. I am generating the pulses using an Arduino Uno and have maxed out its ability to pulse, I need to count up to 800000 pulses in a 30s period and trying to test its ability to be able to do it.Thanks for any advice

author: JS
author_rank: Frequent Contributor
timestamp: July 27, 2018, 12:53:25 am
content: That's 26 kHz, easy for a micro tunning at a few megs but nterupts isn't the way to do it.Use hardware counters and pulse generators, periphericals all micro has. Both are likely in the timers modules, a counter would use an external pin as clock source and you stop the count after the time is fine and read the value.The pulse generator is another timer togglin a pin every N counts, something like pwm is generated but slightly different configurations for the peripherical registers.This applications is when arduino often falls short and you need to use conventional programming, good thing is you can do it inside the arduino enviroment. Often just writing registers directly using their names, in arduino due you need to add a prefix (IIRC "REG_") but you can keep using the arduino functions with some caveats, like if messing with timers pwm and other timing functions might not work as expected and interfere with your program. But other functions as toggling other pins, math and logic functions, etc. are usually fine. All generic C functions will work without problems.This is a good time to make the jump, then you can jump to other plataforms wich require a bit more setup than what the arduino enviroment offers but also much more flexibility. I'm using STM32 and is great but still use arduino once in a while for some applications, it's great for small stuff and have a working peototype in minutes, once you want a bit more bare metal, as the people getting out of arduino calls it, is much more powerful.JS

author: threephase03
author_rank: Contributor
timestamp: July 27, 2018, 01:08:50 am
content: Thanks for the feedback, and ill keep it in mind. I just put it on a function generator set at 30kHz and timed it with a stopwatch for 30s.And counted over 900000 calculated to be about right considering the timing by hand. I think for the quick thing I'm building it should be alright.
Couple inductor current spike in flyback converter - Page 1
Forum section: electronics / beginners

author: Patrick66
author_rank: Regular Contributor
timestamp: January 07, 2024, 08:37:16 am
content: Hello, I would like to ask why is there a sudden current spike when the inductor current increases or decreases? Thank you.

author: MarkT
author_rank: Frequent Contributor
timestamp: January 07, 2024, 10:02:28 am
content: Well you are driving a MOSFET from a perfect voltage source, and since MOSFET gate is basically a capacitor you'll be seeing immense current spikes. Add 10 to 100 ohms in series with the gate to stop this.

author: Patrick66
author_rank: Regular Contributor
timestamp: January 07, 2024, 03:07:50 pm
content: Hello Sir, do you mean like this ?
Coupled ferrite to isolate DC-DC power supply - Page 1
Forum section: electronics / beginners

author: Yaroooo
author_rank: Regular Contributor
timestamp: April 10, 2020, 10:40:20 am
content: Hi all,as title, I'd like to add an isolated power supply to my circuit. I've a unknown power source that is declared 24V DC that I must use to power my circuit in an isolated way. I'll have an absorption between 0.5A to 1A on my circuit with an operative voltage of 12V.There're different already made isolated DC-DC , with high prices, that convert from 24v to 12v. But maximum ratings are below my requirements, since input voltage may be higher and output current is very low.Searching I've found this two type of products:LPD4012-331NRBMSD1278-472MLDThere's different type of converters application listed on this product datasheets. What is the lowest cost switching controller that I can pair with this circuits to perform DC-DC step-down? (something like a historical low cost IC)I've also another question, can I just use this coupled ferrite like a transformer to power supply a LDO or a switching? I mean put it between my power supply and my voltage regulator, since it's 1:1 ratio and DC:DC I should not have additional components instead some caps. In this way I'll have ad isolation between source and board.Thanks for any answer to my newbie question!

author: gbaddeley
author_rank: Regular Contributor
timestamp: April 11, 2020, 06:52:15 am
content: A ferrite isolating transformer will not work DC - DC. It requires a fairly high frequency AC driver, and then convert the transformer secondary back to DC. That’s why isolated DC - DC converter modules are not very cheap, but you are probably better off by using one.
Coupled Inductor Circuit Simplification - Page 1
Forum section: electronics / beginners

author: Etesla
author_rank: Regular Contributor
timestamp: June 27, 2024, 03:39:42 pm
content: Fun math problem if you're into that sort of thing. Can anyone figure out how to do this transformation? I'm starting with 4 inductors and some parameters L12, L34, and K. I want to transform that circuit into a simpler one with only two inductors and one coupling statement. So basically can anyone solve for A, B, and C in terms of L12, L34, and K?[ Specified attachment is not available ]
Coupling 20Hz-20kHz triangle wave - Page 1
Forum section: electronics / beginners

author: bonzer
author_rank: Regular Contributor
timestamp: March 23, 2020, 10:24:50 am
content: Hello everyone! I'm working on a project where I need to cut DC component of a triangle wave in 20Hz-20kHz triangle wave.I tried many ways for example 100nF and 200kOhm RC high pass filter but the problem is that I can't check its working for sure: when I put it into the simulator for low frequencies it takes too long to finally see the DC component cut (maybe a second or less) but who knows? I can't see it. At high frequency it takes less so I can see it.When I try to impose a start time later like 900ms the simulator suffers anyway because it keeps on calculating till that instant even though it doesn't share them.What values of capacitor and resistance would guarantee me 0 volt average for the whole range of frequencies?

author: Zero999
author_rank: Super Contributor
timestamp: March 23, 2020, 10:53:09 am
content: Quote from: bonzer on March 23, 2020, 10:24:50 amThe answer is any value of capacitor and resistor would guarantee an average of 0V, at all frequencies, once the steady state condition has been reached, since a high pass filter has a DC gain of zero.In theory, the voltage on the resistor will never reach zero. It will be be 36.8% of the initial DC voltage, after one RC time constant and 36.8% of that after two RC time constants etc.The lower cut-off frequency will also be determined by the RC time constant and is the frequency when the voltage drops to 70.7% of the input. FC= 1/(2pi*RC).https://en.wikipedia.org/wiki/RC_circuit

author: Zero999
author_rank: Super Contributor
timestamp: March 23, 2020, 07:18:21 pm
content: RC circuit sim.asc(0.66 kB - downloaded 42 times.)
Coupling a signal from one wire to another - Page 1
Forum section: electronics / beginners

author: pigtwo
author_rank: Regular Contributor
timestamp: September 21, 2015, 05:14:15 pm
content: Hello all,I working on some testing for EMI susceptibility. I have an input(sensor) wire that I wish to couple a signal onto. I have a function generator that I want to use to apply different frequencies to the system.I was going to take the sensor wire and wrap it around a wire with the signal from the function generator. My question is how should I terminate the function generator? Should I add a 50 ohm to the end of the function generator signal? Or would just shorting the ends of the function generator work the best?A final note, this is not a very quantitative test so I'm not really looking for the perfect solution, just something that I can get working semi-quickly.Any other suggests also welcome.Thank you!

author: N8AUM
author_rank: Regular Contributor
timestamp: September 27, 2015, 08:10:45 pm
content: Try it both ways. The amount of coupling will depend on many variables like frequency, number of turns ...
coupling cap gnd reference - Page 1
Forum section: electronics / beginners

author: electrolust
author_rank: Unknown
timestamp: July 16, 2017, 03:54:45 pm
content: Voltage is differential.So if I have a single supply op amp design and apply a bias to the input signal, as far as the op amp is concerned it still has +/- supply and the signal reference is at GND. (modulo variation in bias level due to circuit design)With a coupling cap, that isn't connected to any reference level (signal in, signal out), how is it that DC voltage is blocked? How can the cap know what is earth/true GND vs what is signal GND?

author: bson
author_rank: Unknown
timestamp: July 16, 2017, 07:25:07 pm
content: It sits in a closed circuit, and at w=0 the voltage drop across it is the bias voltage. Therefore, the output sits at the input minus the bias voltage. (If you view it purely as a black box.) It's worth noting also that it settles at whatever voltage results in no current, which depends on the rest of the circuit, it's just in amplifier and filter circuits this tends to be either 0V or some other specific bias point for that circuit.

author: electrolust
author_rank: Unknown
timestamp: July 17, 2017, 02:12:38 pm
content: Quote from: bson on July 16, 2017, 07:25:07 pmahh, of course
coupling capacitor - Page 1
Forum section: electronics / beginners

author: yalect
author_rank: Regular Contributor
timestamp: July 11, 2017, 10:50:01 am
content: Hello,I would like to ask you I want to choose capacitor for transistor amplifier input and output.please, can you led to me how I can do that or what's formulas and conditions?Thank you

author: Benta
author_rank: Super Contributor
timestamp: July 11, 2017, 12:00:43 pm
content: For the input cap, use the input impedance and calculate the CR divider for a reasonable cut-off frequency, say 20 Hz.For the output, make an assumption about the minimum impedance of the load and do the same calculation.

author: yalect
author_rank: Regular Contributor
timestamp: July 11, 2017, 11:10:37 pm
content: Hello, thank you for your replywhat do you mean by the CR divider for a reasonable cut-off frequency, or can you give formula or example?Thanks

author: Paul Moir
author_rank: Frequent Contributor
timestamp: July 12, 2017, 12:39:59 am
content: Commonly called a "High pass RC filter" or maybe a "first order passive high pass RC filter. The R is the input impedance of your next stage, while the C is your coupling capacitor.Lots of good info out there, such as:http://www.electronics-tutorials.ws/filter/filter_3.htmlWith the corner frequency Fc=1/(2*pi*R*C) being the one of interest to you.

author: yalect
author_rank: Regular Contributor
timestamp: July 12, 2017, 11:00:32 am
content: Hi,thank you for your reply but what's a simplest way to determine The appropriate value of coupling capcitor (input and output) ? considering the input impedance of the amplifier if we know that Extracting that impedance is something complicatedand.thank you

author: Paul Moir
author_rank: Frequent Contributor
timestamp: July 13, 2017, 04:40:13 am
content: Well, if you can't compute it or estimate it, you can only measure it or simulate it with something like LTSpice. I would think it would be fairly trivial to measure it by inputting a signal from a signal generator via a resistor, and measuring the signal on either side of the resistor with a multimeter. Just make sure the frequency of the signal is within the multimeter's AC volt frequency limit.
Cover up via pcb via that is creating a short? - Page 1
Forum section: electronics / beginners

author: Jackster
author_rank: Frequent Contributor
timestamp: May 03, 2018, 10:18:16 pm
content: I have a tiny via on my PCB that is creating a short between a LED pad and ground.(the via and pad are too close to each other so the larger LED part is shorting)What is the best way to cover this via?Presuming solder mask? Any cheaper way, as a bottle of this is like £15...Conformal coating? Can get it in a pen for £5ThanksJack

author: Mr.B
author_rank: Unknown
timestamp: May 03, 2018, 10:29:21 pm
content: Is Capton tape an option?

author: Jackster
author_rank: Frequent Contributor
timestamp: May 03, 2018, 10:30:19 pm
content: Quote from: Mr.B on May 03, 2018, 10:29:21 pmOhh that could work, and would resist the heat from soldering.Ill give that a go tomorrow!
coverting analog to digital meters on old test equipment - Page 1
Forum section: electronics / beginners

author: trog1058
author_rank: Newbie
timestamp: May 07, 2016, 04:07:53 pm
content: any material that can help pick the best meter to replace analog meters?

author: Signal32
author_rank: Frequent Contributor
timestamp: May 07, 2016, 04:37:05 pm
content: You mean something like this ?http://www.aliexpress.com/item/Green-LED-display-Color-DC-0-4-3000-33-000V-0-36-Digital-Voltmeter-three-Wires/1320678280.html

author: trog1058
author_rank: Newbie
timestamp: May 07, 2016, 04:58:23 pm
content: I was thinking of material that shows if I need voltage or current for different types of test equipment. If a meter is plus and minus is there a digital replacement. Just a book or pdf that would bring me to the best type of meter for what ever type of analog is to be replaced.

author: barry14
author_rank: Regular Contributor
timestamp: May 08, 2016, 12:30:29 am
content: It is unlikely that you will find literature directly useful to you for this issue. Each meter will have to be considered on an individual basis. Analog meters can vary widely: some are designed to read voltage and have a relatively high input resistance, some are designed to read current and have a low input resistance. In many cases, there are external resistors that set the type of reading and the range scale. Some meters have zero at the center. The damping of the meter may be significant in some applications so replacing it with a digital meter may be difficult. Also, some meters are designed to be used to set a peak or a null; again these may be difficult to replace with digital meters. To repeat, there is too large a range of possible analog meter functions to generalize how to replace them with a digital meter.
Cox Minibox IR extender - Page 1
Forum section: electronics / beginners

author: Peabody
author_rank: Super Contributor
timestamp: November 19, 2024, 05:33:11 am
content: I have a Cox Minibox cable box. It has a 3.5mm jack on the back that's labeled IR In. I'd like to put the Minibox behind something, but still use the IR remote, and I think this is what the IR In jack is for. Cox may be willing to give me an IR extender, but if not, I wonder if I could just make one. My guess is it would just be a standard 38KHz IR receiver/demodulator powered by 5V. That would mean a TRS connector. Does that sound right? Anybody have experience with this kind of extender?

author: u666sa
author_rank: Frequent Contributor
timestamp: November 19, 2024, 06:51:13 am
content: https://manuals.plus/wp-content/sideloads/cox-mini-box-digital-adapter-manual-original.pdfThe other question is what you doing with a cable box? Because these days cable and dish are outdated technology. Now we have online streaming services with whole bunch of channels. For example I have a Kion here, which is $4 a month, but I don't pay, I just use promotional promo codes and watch for 1 month for free, then before subscription ends, I unsubscribe and go get another promo code. There is a forum topic and people post promocodes. I've been watching equivalent of cable for the past 2 years without paying a dime.Cable and dish are outdated primarily because of price and picture quality. Most channels look bad on your big screen 4K TV. Plus no two remote none sense.

author: Peabody
author_rank: Super Contributor
timestamp: November 19, 2024, 03:22:10 pm
content: My condo association has a bulk deal with Cox to provide cable TV to everyone. I pay for it as part of my monthly HOA fee. So I have to pay for it whether I use it or not. So that's what I use. And I don't have a 4K TV, so the picture quality isn't an issue. Thanks for the info on the cox IR extender. I will pick one up.

author: Peabody
author_rank: Super Contributor
timestamp: November 21, 2024, 03:40:12 pm
content: In case anyone sees this thread in the future, I want to report that Cox no longer gives away IR extenders, but will ship one to you for $9, which is about the same as these things sell for elsewhere. What they sent me was a Stealth Remote Prism, part number PTS-PRISM-38-3 made by ProTVSolutions. It is a standard 38KHz IR receiver with a 3-foot cord. It has a 3.5mm TRS socket, and the cable is male at both ends. Tip is the 5V supply, Ring is data out, and Sleeve is ground.I expected that plugging in the extender would disconnect the receiver inside the Minibox, but it doesn't. So if both receivers are trying to demodulate IR at the same time, there is a conflict, and it doesn't work. You have to completely hide the Minibox from the remote's IR. Then the extender seems to work ok.The extender module can be placed on a shelf, or it can be mounted to the bottom of the back of the TV so that it sticks down a bit to make it visible from the front (that's where the prism comes in). I found one video:
CP2102: diode before REGIN/VBUS inputs? - Page 1
Forum section: electronics / beginners

author: dornovelk
author_rank: Unknown
timestamp: June 08, 2019, 06:29:39 pm
content: While diving into the schematic for the CP2102 USB/UART today I realized I made a mistake on my PCB design and didn't connect the VBUS pin coming off of the USB connector directly to the REGIN/VBUS pins on the CP2102 as instructed on the datasheet. Instead, I accidentally connected both of these pins to the VBUS line after it went through a protection schottky diode (Per the datasheet, REGIN & VBUS both expect 5V, and VBUS does indicate that it should be connected directly to the VBUS net coming off USB). Looking at the datasheet for the diode, forward voltage drop at my worst case current is 470mV. For context, after the diode, the 5V rail is connected to the 5V input pin of a voltage regulator.I haven't received the parts yet, but would this be a showstopper and require revision? Or could I get away with the design as is for testing purposes? (this is just a prototype).Thanks!

author: janoc
author_rank: Super Contributor
timestamp: June 08, 2019, 08:29:05 pm
content: That could well be a showstopper because USB VBUS is defined to be 5V +-5%, so it could be anywhere from 4.75 to 5.25V. If you are at the bottom end of that range, add voltage drop of the cable and with the extra voltage drop of the diode you could be easily below the 4V minimum input voltage for the REGIN pin. In that case all bets are going to be off. That's going to be a very marginal design. Do you really need that diode there?

author: dornovelk
author_rank: Unknown
timestamp: June 08, 2019, 10:42:56 pm
content: Quote from: janoc on June 08, 2019, 08:29:05 pmThanks for your response! I was leaning towards removing the diode from the circuit for now and just letting USB VBUS go directly to the input pin of the AP2114H-3.3 & directly to the CP2102 pins (per datasheet requirement).
CPU registers - emulated or real? - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: October 31, 2015, 02:56:10 pm
content: I started recently playing with a MIPS CPU( made by Broadcom). As far as I know it allows to use a Broadband Studio to communicate with that CPU.That MIPS CPU has Read/Write registers. I can write to these registers and in the Broadband studio I can see the new value was written. But if I restart mainboard, that uses the MIPS CPU, there is the previous value before I changed it.Do you think the Broadband studio onlyemulatesthose registers and I write tonotthe real registers?I used a logic analyzer to check how the Broadband studio writes to registers.It does write to CPU but the address is different than a documentation says.For exampleAddress Offset = 32'h001a_00d8Physical Address = 32'h101a_00d8but I can not see that address during sniffing with a logic analyzerAny idea?

author: Paul Price
author_rank: Super Contributor
timestamp: October 31, 2015, 04:30:10 pm
content: The upper address bit is probably ignored in decoding the address of the registers for reading and writting.The registers are probably not reset when you restart the mainboard, so the previous values remain.
CPU Reset  - Page 1
Forum section: electronics / beginners

author: gkmaia
author_rank: Frequent Contributor
timestamp: February 15, 2020, 03:08:02 am
content: This circuit attached is an extract of my Roland RD300s circuit.My question regards the RESET pin. By looking at the schematics i understand is the reset is HIGH the CPU will be halt. In most CPUs the reset has to go LOW to halt thee CPU. But according to this schematic it is the opposite.Anyway... by looking at the circuit I see when ON a voltage being applied to the base of Q2, Q2 then conducts bringing the base of Q1 to ground. Q1 the is open holding it's collector and the RES pin at +5v. And by the schematics and IC datasheet if res is HIGH the IC is halt.What am I getting wrong here?

author: ataradov
author_rank: Super Contributor
timestamp: February 15, 2020, 03:49:12 am
content: During steady state Q1 is open, which keeps Q2 closed. So reset is high during normal operation, just like any other MCU.And I could only google some repair manuals, not the datasheets. If you are judging by not having a line over the RESET name, then I would not trust that. If there is some test that explicitly stated that reset is active high, then where it is?Also, I found a manual where RES pin is marked as active negative. And the same exact circuit is used.

author: gkmaia
author_rank: Frequent Contributor
timestamp: February 15, 2020, 05:34:33 am
content: Thanks!That solves the problem pretty much.
CPU socket replacement soldering profile - Page 1
Forum section: electronics / beginners

author: geomih
author_rank: Newbie
timestamp: December 12, 2023, 04:50:52 pm
content: Hi All - I am hoping someone can help with some pointers (complete noob here!)I have recently purchased a Scotle HR460 BGA reball machine (it's a bit old and I think the company no longer exists either), but as far as I can tell it is a competent and unmolested machine that should be good enough for my needs.My biggest problem is that it came with no profiles, and I must re-create all of them from scratch, something that is very scary for someone that doesn't really know what they are doing.The simple stuff like a small memory module isn't a big deal because there are a few example profiles in the manual – but for more than that the manual is no help as it is very basic.Any ideas?
CPU socket tester?? - Page 1
Forum section: electronics / beginners

author: azigta
author_rank: Regular Contributor
timestamp: July 31, 2014, 08:25:26 pm
content: Hi, I normally have cpu´s to test motherboards, usually intel 775 socket and below, but recently I´m repairing 1155 and 1156 socket motherboards and I don´t have the cpu´s to test them.So I searched on internet and I found something like a cpu with a lot of lights in it. The lights are supposed to tell you if that motherboard is ok or not.According withthispage, it´s what I think it isAnyone here can confirm this? It could help me a lot testing motherboards, but I don´t want to buy it without being sure...Also, anyone with this thing can tell me what does it test exactly? does it test everything or what? thanks

author: wraper
author_rank: Unknown
timestamp: July 31, 2014, 09:05:36 pm
content: Just buy cheapest low end cpu's for those sockets. That thing is not supposed to tell you is it ok or not. That thing is meant to do some (pretty crappy) diagnostics when repairing the faulty motherboard.What you want do exist as a part of automated motherboard test system in the factory. Guess the size and how much it cost.

author: cpt.charlie
author_rank: Contributor
timestamp: July 31, 2014, 10:22:46 pm
content: These boards are used to check voltages at the cpu socket, it won't tell you if the motherboard is defective or not.

author: amyk
author_rank: Super Contributor
timestamp: July 31, 2014, 10:23:22 pm
content: Yes, these are essentially logic probes for all the signals on the CPU. They'll alert you to some common faults but won't check the actual functionality of the motherboard, and are meant to be used for a quick check first so you don't damage a real CPU e.g. with overvoltage when trying it in an unknown mobo.There's ones for LGA2011 too.

author: azigta
author_rank: Regular Contributor
timestamp: July 31, 2014, 10:24:38 pm
content: ok then I´ll buy a cheap 1155 celeron xD thanks
CQ3 100X4 balance charger needing cables - Page 1
Forum section: electronics / beginners

author: Nickk2057
author_rank: Regular Contributor
timestamp: April 07, 2023, 08:03:22 pm
content: So I have a Bguad CQ3 charger that has banana jacks on it. I am using it to charge my Prius battery modules through a cycle to get its capacity and rejuvenate them. Only one issue. The cables I have have high resistance through them causing them to have a voltage drop and get hot. Where can I get a good high current alligator clip to banana jack cables from that can handle the high current?Attached is my setup I am running. The charger I have on the left is the one I am using, the others have the cables I gotten from the hobby shop that went to banana jacks to XT-30, XT-30 to battery clips. Oh... And it has to be around 3m or more. Trying to make it a better type of setup than this.Thanks bloggers!

author: Nickk2057
author_rank: Regular Contributor
timestamp: June 19, 2023, 11:44:02 am
content: Bump

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 19, 2023, 01:33:35 pm
content: How high is the resistance? What AWG are the wires?Something must went really wrong if it gets hot just from 1.7A

author: Nickk2057
author_rank: Regular Contributor
timestamp: July 15, 2023, 11:27:12 am
content: They was real thin. I decided to make my own now since I would not find much heavy duty cables like that to use. Would be best to use 12AGW cables since they are thick enough that can have low resistance just so the charger would read the battery correctly. When I had the cables I got from ebay, the charger would read the voltage higher than what it really shown on the battery.
CR6842S ACDC HELP - Page 1
Forum section: electronics / beginners

author: franksterb92
author_rank: Contributor
timestamp: April 21, 2024, 09:24:19 pm
content: I Reverse Engineered the WX-DC2412 ACDC Module AND made PCB containing the circuit of this module plus some regulators but i cannot get it to work ive tried different start up resistors and capacitor values kind of stuck and dont really know what to do now any help would be greatly apricated ive attached the schematic of the acdc section

author: aliarifat794
author_rank: Regular Contributor
timestamp: April 22, 2024, 12:29:48 pm
content: Please check if you have mistakenly reverse polarised any components like the diodes, capacitors etc.

author: franksterb92
author_rank: Contributor
timestamp: April 22, 2024, 10:58:07 pm
content: Unfortunately I have done that does anyone know a way to make sure the chip is starting up it seems like it won't start

author: floobydust
author_rank: Super Contributor
timestamp: April 22, 2024, 11:26:40 pm
content: Post voltage measurements, at least on the IC. The ones on your schematic are from a working PSU and not helpful.Do be extra careful as the primary HV filter cap will be holding a charge if there is no load or bleeder resistor present. Shock hazard.

author: franksterb92
author_rank: Contributor
timestamp: April 23, 2024, 01:41:38 am
content: Ok I will wen I get home and your right those voltages are from working one but from my troubleshooting the voltage at the vdd pin of ic is almost the same as a working one and the Vin pin the same although on my pcb it seems to be picky of the capacitor value at c4 but not picky on the module itself like the voltages will be stable with 0.1uf 100v cap but not 100uf 100v cap don't make any since

author: franksterb92
author_rank: Contributor
timestamp: April 24, 2024, 07:32:35 pm
content: from testing I've fond that R7 is open I'm waiting on replacement hopefully this is why my board isn't working cause this project is driving me crazy but I've learned so much along the way

author: floobydust
author_rank: Super Contributor
timestamp: April 25, 2024, 12:44:49 am
content: If current-sense resistor R7 goes open, this is usually because it's a fusible/flameproof part that got overloaded from a mosfet shorting out. It damages the IC and new mosfet if you are not careful to check those parts too.A dim light-bulb tester to power this is also a good idea to save on fuses and smoke. Even a 25W lamp is all you need to power it up with no load.

author: franksterb92
author_rank: Contributor
timestamp: April 26, 2024, 04:49:17 pm
content: it works now i got the replacement part and replaced last night and it works wow how i way over complicated this fault in my mind as i never put together a smps pcb before lol oh well i learned so much about smps design
Cracking on mains filtering capacitors. Something to worry about? - Page 1
Forum section: electronics / beginners

author: bigfoot22
author_rank: Contributor
timestamp: December 29, 2022, 12:18:53 pm
content: deleted

author: wilfred
author_rank: Super Contributor
timestamp: December 29, 2022, 12:39:13 pm
content: YES.They will fail eventually. And if you're as lucky as me it will be in warmer weather when you can leave the windows and doors open to let the stink out.

author: wraper
author_rank: Unknown
timestamp: December 29, 2022, 12:39:27 pm
content: Any X2 or X1 capacitors of suitable dimensions and capacitance will be fine. If you leave these they may eventually explode.

author: MrAl
author_rank: Super Contributor
timestamp: December 29, 2022, 01:38:09 pm
content: Physical damage to a capacitor always means replacement.Electrolytics go frequently and so have to be replaced after some years of service.I've seen this happen several times over the years especially with power supplies. The cap ESR goes up so the cap can not longer filter properly. Once replaced, everything works normal again.I posted this before but the post disappeared.

author: tggzzz
author_rank: Super Contributor
timestamp: December 29, 2022, 01:48:48 pm
content: Quote from: bigfoot22 on December 29, 2022, 12:18:53 pmAh. "Rifa madness".Replace ASAP; I've had several detonate after mains has been applied for a few minutes. Minimal detonation is simply large amounts of unpleasant smoke. But don't count on that; I've had one remove itself together with a series resistor and PCB prepreg.I normally use any suitable X/Y capacitor, but where dimensions were critical I had to put in new Rifas. I reckon they will have a longer life than I will

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 29, 2022, 02:17:05 pm
content: yes replace the one that you see crack. Some people replace all capacitors in a cassette deck but as you can see there are so many it would be a lot of work and a lot of chance for one to make mistakes.

author: wraper
author_rank: Unknown
timestamp: December 29, 2022, 02:21:51 pm
content: Quote from: BeBuLamar on December 29, 2022, 02:17:05 pmReplace all Rifa paper caps as you see them. Especially is some of them already have signs of damage. Leaving them asks for trouble eventually.

author: wraper
author_rank: Unknown
timestamp: December 31, 2022, 07:57:06 am
content: Quote from: bigfoot22 on December 31, 2022, 05:19:59 amIf you mean Kemet PME series, those are the same paper caps as they acquired RIFA in 2007. They likely got never fixed as caps from mid-late 2000's already fail the same way as caps from 80's and 90's.
crafting an app: paintbox - Page 1
Forum section: electronics / beginners

author: paintinx
author_rank: Newbie
timestamp: March 09, 2024, 03:33:55 am
content: Good morning,I am new here and so I will write a few information about me and than ...I really hope you are not going to kick me out here!//btw I am sorry for my poor englishI am in "my" 50th - made a lot of things using the Quantel Paintbox and HAL technologyand currently I make a lot with Adobes Creative Suite //you know, the layer options at Paintbox were special.Since I begun to design sumpthin using the "new" technology I was longing for the return of Paintbox.So I decided to program an app using Universal Windows Platform and also Windows Forms.Years flew by in a blink ^^To be clear, I have read a lot in this blog and assume that it is more for hardware topics butperhaps there´s someone here who has delved into the matter before ...The time of A.I. is changing evrythin and yet, paradoxically, nothing at all - like having a cake and eating it too ^^If someone is interested in trying sumpthin with this great former technology called "Paintbox" - please write a message.You are welcome!paintinx
Simple, manual ranging, multimeter for free - Page 1
Forum section: electronics / beginners

author: stafil
author_rank: Regular Contributor
timestamp: April 14, 2020, 01:24:59 am
content: I have a spare multimeter that I don’t need anymore and instead of tearing it apart for parts or throwing it away I was wondering someone starting their electronic hobby that doesn’t have one that would like to have it.Completely free, including USPS postage. US only please though.PS: I posted here, because it's mainly for beginners, but if you think this should be in the Buy/Sell/Wanted section, please feel free to move.

author: Gregg
author_rank: Super Contributor
timestamp: April 14, 2020, 01:55:34 am
content: This offer is very nice of youSince Harbor Freight no longer seems to be giving their cheap meters away, you will make some newbie's day.Thanks (I hope I'm speaking for the whole eevblog community)
CRC calculation help (C Code) - Page 1
Forum section: electronics / beginners

author: Rerouter
author_rank: Super Contributor
timestamp: May 30, 2015, 12:26:51 am
content: I am trying to understand a block of code for calculating a CRC in the hopes of improving / modifying it, To me it seems odd that each bytes while loop spins away 255 times?Code:Var17 = 0x05; //DATA for calculationVar18 = 0x00;Var19 = 0x00;Var20 = 0x00;Var14 = 0xFFFF; //CRC initial valueVar15 = 0; //counterVar16 = 0;While(Var15 != 255){Var15 = Var15 + 1;Var14 = Var14 ^ (Var17);While(Var16 != 8){Var16 = Var16 + 1;if((Var14 & 0x0001) != 0){Var14 = (Var14 >> 1) ^ 0x8408;}else{Var14 = (Var14 >> 1);}}}Var14 = Var14 & 65535;Var15 = 0; //counterVar16 = 0;While(Var15 != 255){Var15 = Var15 + 1;Var14 = Var14 ^ (Var18);While(Var16 != 8){Var16 = Var16 + 1;if((Var14 & 0x0001) != 0){Var14 = (Var14 >> 1) ^ 0x8408; }else{Var14 = (Var14 >> 1);}}}Var14 = Var14 & 65535;Var15 = 0; //counterVar16 = 0;While(Var15 != 255){Var15 = Var15 + 1;Var14 = Var14 ^ (Var19);While(Var16 != 8){Var16 = Var16 + 1;if((Var14 & 0x0001) != 0){Var14 = (Var14 >> 1) ^ 0x8408;}else{Var14 = (Var14 >> 1);}}}Var14 = Var14 & 65535;Var15 = 0; //counterVar16 = 0;While(Var15 != 255){Var15 = Var15 + 1;Var14 = Var14 ^ (Var20);While(Var16 != 8){Var16 = Var16 + 1;if((Var14 & 0x0001) != 0){Var14 = (Var14 >> 1) ^ 0x8408;}else{Var14 = (Var14 >> 1);}}}Var14 = Var14 & 65535;input data is 05000000, I've substituted it in the code to try and make things clearer, expected result is 6D76 or 766D, (do not know the eadianess) If i could please get some help understanding just what it is doing, or suggestions for making it run better, it would be appreciated, only thing to note is a do not think the script language supports look up tables,I've been shown in the past that the same CRC can be calacutled by the settings below, but this really confuses me, as with both cases i haven't been able to replicate its output on any online calculator:CRC 16 BitsInitial: FFFFPoly: 1021Xor In/Out: 0Reflect in/ Out: True,

author: marshallh
author_rank: Unknown
timestamp: May 30, 2015, 02:26:59 am
content: polynomial is 0x1021.So polynomial is x^13 + x^5 + 1 (same as x^0)That may help you. I'm not sure why that code is written like that, I usually do it in HDL
Creality Ender 3 Fan Not Working - Page 1
Forum section: electronics / beginners

author: ZayneTech
author_rank: Contributor
timestamp: January 27, 2019, 11:51:03 pm
content: Hi Everybody!This is my first post, and I would like to ask why my Ender 3's control box fan isn't working after an upgrade to the TH3D Firmware.I have searched good old Google for answers but I didn't find anything.Any help would be appreciated.

author: Zorc
author_rank: Contributor
timestamp: January 28, 2019, 08:27:32 am
content: HiThis will be my first post as well thenI doubt it would be a firmware problem. I've compiled my own from stock Marlin without any problems, so a custom TH3D firmware specific for this printer should be tested and fine.Are you sure it worked before the upgrade? And better yet, is your part cooling fan working??If you just turned it on after the upgrade and started to check things and suddenly noticed the control box fan isn't working you should know this:The control box fan is connected on the same controller output as the part cooling fan on the Ender-3 (at least it was on my version), when you just turn your printer on the fan is off ...And if you don't have the part cooling fan on (during printing) your electronics can get a bit hotI simply rewired my control box fan, so now it is always on when the printer is on.

author: ZayneTech
author_rank: Contributor
timestamp: January 29, 2019, 02:29:02 am
content: Thanks for the reply. I ended up rewiring it too

author: beanflying
author_rank: Super Contributor
timestamp: January 29, 2019, 03:20:37 am
content: I have a couple of Ender Pros which at least have the fans facing downwere they not thinking at the time with the EnderI am part way through putting them and my CR-10 into enclosures and as part of that I have done a prototype enclosure to get the elcectronics away from the hot bits all together and outside.This is the CR-10 (Power Supply is now Ender Style and Remote) one and I will be doing a modded version for the Ender boards/display in the next few weeks. Happy to share it here when it is sorted or roll your own based on this idea

author: ZayneTech
author_rank: Contributor
timestamp: January 29, 2019, 09:18:06 pm
content: That looks great! I hope to hear from you soon