hybridfree/eevblog-posts huggingface dataset:
UART/SERIAL VGA Controller - Page 1
Forum section: electronics / beginners

author: pyromaniac4382
author_rank: Contributor
timestamp: August 14, 2014, 03:40:26 pm
content: I am currently working on a z80 computer. I have no output so far to a screen. I could hook up a UART & RS-232 level shifter then off to a PC running a terminal emulation, but I want a stand-alone system at the end of the day. I picked up a VGA monitor and a PS/2 keyboard on the cheap and would like to use that. So the question is, how would you output to a VGA monitor? I really only want a serial terminal, but later could dabble in generating actual images. I figured what I could do is take the output of the UART, and somehow show this text on the VGA monitor. Where do I even start?

author: PepeK
author_rank: Regular Contributor
timestamp: August 14, 2014, 03:53:38 pm
content: Z80 and VGA output ?You need something like videocard for your Z80. Would not it be better to use some modern computer having HDMI output, sound, keyboard and a lot of Linux based software like Raspberry ? Or is your plan to reinvent a wheel ?

author: mariush
author_rank: Super Contributor
timestamp: August 14, 2014, 04:04:12 pm
content: I'd recommend using another microcontroller to act like a video card, taking uart/i2c data in and output s-video or composite signal, generating something like 320x240 or 640x480 in real time or something like that.With a bit of effort you can output vga to a monitor as well... otherwise, there are svideo/composite to vga converters out there.

author: Kjelt
author_rank: Super Contributor
timestamp: August 14, 2014, 04:07:40 pm
content: Did that with some old SAA Philips teletext chip a long long time ago.Then there were also serial input video text overlay cards costing a bundle.Nowadays I would just buy an old laptop with RS232 and be done wit it

author: geek
author_rank: Unknown
timestamp: August 17, 2014, 01:46:03 am
content: Just make your own video card using CPLD/FPGA

author: westfw
author_rank: Super Contributor
timestamp: August 17, 2014, 08:25:52 am
content: If you're not intent on building it yourself, you could use one of these modules:http://microvga.com/there are a lot of projects that use an Atmel AVR or other microcontroller to drive a VGA monitor at relatively low resolution. here's a couple:http://tinyvga.com/If you're interested in building things yourself, a good place to start would be with Lancaster's classic "TVT Typerwriter Cookbook":http://www.tinaja.com/ebooks/tvtcb.pdf

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: August 17, 2014, 05:35:34 pm
content: If you want the easy way out, look at the Picasso µVGA-III. Connect via serial, program & go. It has a micro-SD slot so you can put pre-generated graphics on board that can be called up via serial commands. You can do animation or video that way.https://www.sparkfun.com/products/11767

author: rob77
author_rank: Super Contributor
timestamp: August 17, 2014, 06:01:03 pm
content: I would try to find a ISA VGA cradnot a problem to drive a ISA card with a 8bit CPU or micro.
UAV project (Hobby) - Page 1
Forum section: electronics / beginners

author: 5teveG
author_rank: Newbie
timestamp: March 06, 2024, 02:39:42 am
content: Hi Guy's,I'm a newbie here. Found the forum looking to solve another issue.Toolmaker by trade with some PLC and amateur electronics experience.I've started a project to build a UAV with radio transmitter and later autopilot.Fully aware you can buy the electronics but prefer/determined to learn how to build from scratch.Long term, I will add my own features.Messed around a lot with Arduino and RPi prototyping boards. Currently focused on the Teensy 4.0 as the STM Cortex M7 appears to be suitable for now.Purchased the Sparkfun Micromod Teensy, M2 format processor board due to its size and ease of use.I found an old Carbon Aeronautics tutorial with some reasonable info. I plan to build this simple Quad first.Curious if anyone else has been down this path and willing to share some wins and misfortunes.ThanksSteve

author: Jwillis
author_rank: Super Contributor
timestamp: March 06, 2024, 03:08:07 am
content: You probably want to scour the RC fixed wing sources. RC fixed wing has changed a lot electronically since I was young. I've kind of put aside my RC hobby due to time and money but have a look atMATEKSYSF405-Wing control modules. These have the ability to include GPS, Audio Video, Advanced flight control and guidance and telemetry.Unfortunately the F765 was removed because of chip shortages. Very sad. I liked that one.Modified to repair link

author: Andy Chee
author_rank: Super Contributor
timestamp: March 06, 2024, 03:15:29 am
content: Obvious question first, are you an existing RC pilot with some flying experience?You definitely do NOT want to debug code whilst learning to fly at the same time!!

author: 5teveG
author_rank: Newbie
timestamp: March 06, 2024, 03:54:53 am
content: Hi Andy,I do have experience flying Quads. Turnkey systems.Have some patience and can fix broken parts if need be.

author: 5teveG
author_rank: Newbie
timestamp: March 06, 2024, 03:59:27 am
content: Yep, most of the info online is old.I do have a couple of Mateksys boards I've used before.Thanks for the reply.
Über noob question - Page 1
Forum section: electronics / beginners

author: per4manz
author_rank: Newbie
timestamp: March 09, 2019, 01:27:07 am
content: I am working on a Macbook Pro board and see "xw7100" listed on the boardview near the backlight driver. Boardview & schematic indicates pin 1 is "GND_LCDBKLT_SGND" and pin 2 is simply ground. However, I do not see anything on the board, not even pads.Told you - über noob question as I am pretty sure that nothing is supposed to be there (and there isn't), but am certainly looking to learn more and understand exactly what that is or isn't.Thanks.

author: Shock
author_rank: Super Contributor
timestamp: March 09, 2019, 08:51:30 am
content: Sounds like a surface mount link between two traces. If in doubt use your multimeter and test resistance between anything directly connected to those two corresponding labels (on the schematic) and to a ground. But when you find inconsistencies double check you are looking at the right schematic or revision.We have a repair section on the forums, if you have repair specific questions post there and include or link to the specific model, schematic and boardview etc.

author: ebastler
author_rank: Super Contributor
timestamp: March 09, 2019, 09:56:14 am
content: A photo would have been helpful, but lacking that, I agree with Shock: It is probably meant for an optional SMD component to connect the two separate ground nets, either a direct link or possibly an inductor? Maybe they were not quite sure what would be required for signal/noise or EMC reasons, and ended up deciding that they could get away without the part.

author: per4manz
author_rank: Newbie
timestamp: March 09, 2019, 05:12:04 pm
content: Appreciate the answer guys. I will certainly repost in the repair section with more details.
uC ADC data to PC/Matlab help - Page 1
Forum section: electronics / beginners

author: OneAmpShort
author_rank: Newbie
timestamp: March 27, 2018, 11:00:38 am
content: Hey all,Currently at uni, and am undertaking a project to sample analogue signals and process the data obtained. I'm looking to understand how best to get this uC ADC data into a PC to use with Matlab. If data is sent to a csv file, I can import it to matlab, but what about reading live data? (I should note that I'm far from a command line savvy person)I've been investigating both Xbee and Bluetooth as an option for PCB to PC link. Beyond getting a connection established, I'm unsure how to translate the sampled data to Matlab for analysis.I'm kind of limited in how i can flash the uC, as the only debugger I currently have is for atmel products. I did look at the ATMega32 chip which has enough ADC channels for my needs, so I'm leaning towards using that. {4 channels ADC only so maybe a smaller uC would be ok}uC program is to be coded in C++.If I understand correctly, I'd be using USART to transmit data via an Xbee (didn't check bluetooth but I imagine its the same). Is there something I'd need to do on the PC end to be able to read the live data effectively, or alternatively write to a file for later import?For now I'm seeking any guidance for anything I need to understand better. At this point it seems doable but a little beyond my skill set.Thanks for any input.

author: djnz
author_rank: Regular Contributor
timestamp: March 27, 2018, 02:36:09 pm
content: Does the uC to PC link have to be wireless?

author: OneAmpShort
author_rank: Newbie
timestamp: March 28, 2018, 12:55:06 am
content: It's not a requirement of the project, but would be helpful in that the uC will be a wearable design. Initially the aim was to get it working and then look to transmit wirelessly later, but I thought it might just be easier to go straight down that route.
UC3843 PWM Controller T symbol - Page 1
Forum section: electronics / beginners

author: biker.josh07
author_rank: Contributor
timestamp: September 15, 2014, 01:35:13 pm
content: I'm building a PWM control circuit using the UC3843 IC. I'm trying to understand the operation of the IC from the block diagram given.I'm just curious as to what the T symbol is with the clock input. Also I'm pretty sure that the SR latch is the NAND type rather than the NOR type but confirmation would be helpful.Thanks,Josh.

author: bktemp
author_rank: Super Contributor
timestamp: September 15, 2014, 01:42:54 pm
content: It is a toggle flipflop that gates every second clock pulse: The duty cycle is limited to <50% and the frequency is halved compared to a 3842.

author: Simon
author_rank: Unknown
timestamp: September 15, 2014, 01:47:32 pm
content: If you referring to Rt and Ct T stands for timing. the clocking circuitry is internal but you use an external resistor and capacitor to set the timing.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 16, 2014, 05:53:30 am
content: Nah, it's only used in the -44 and 45. The -43 and -45 are low voltage versions (UVLO 5V or something like that).So, important to note that the RtCt value used with the 44/45 must be half that for the 42/43 to achieve the same output frequency!For more ideas, check out the UC3808: it's the same basic thing, but it has alternating outputs. It's simply the same logic, but with the opposite phase from the T f/f brought out through logic to a pin driver.Tim
UCC27211 ic  ho side not warking - Page 1
Forum section: electronics / beginners

author: NASK
author_rank: Contributor
timestamp: June 28, 2018, 06:12:03 am
content: I am using UCC27211 ic in TINA but its HO(capture.png) side is not working , is it wrong in model or my circuit (Capture 1.png)?thanks
UCC27524 gate driver - making sure i understand - Page 1
Forum section: electronics / beginners

author: Lino22
author_rank: Newbie
timestamp: February 09, 2024, 07:59:31 am
content: My task is to create a MOSFET switch that will provide pulses of at least 30V with rise time 5ns. I would be happy with 20ns i guess, but getting close to 5ns would make me proportionally happier.Purpose of the switching circuit is to calibrate Tektronix P6015A probe. I can't find and i cannot afford the recommended calibrator, and so i am experimenting in the field of switches, where i am very much a beginner. For this, i need a steep square, the frequency is not that importatnt i guess. In reality the probe is used to measure a radar magnetron with 1/1000 duty cycle.To drive a MOSFET (not yet chosen) i picked UCC2752 driver chip, because of the appealing 1ns rise time.Now, this is a dual driver, and i will be driving one FET - is that still a good choice?Can the input of UCC2752 be driven from a square wave generator i have at hand, which provides 0-10V/80ns rise time pulses?Shall i feed just one input or connect A and B and drive them together? The same question stands for teh outputs A an B.I imagine there is a lot of current from the output and so there resistors in series that limit the current - how shall i choose their size?Would it be beneficial to use push-pull MOSFETS and put the probe between them?Thank you.

author: jonpaul
author_rank: Super Contributor
timestamp: February 09, 2024, 01:38:28 pm
content: Hello great to hear from CZ. What exactly is the scope and application?The 10' P6015A is 75 MHz. A normal pulse gen can supply a 10..20V pulse but needed a 50 Ohm load for specified rise time.TEK P6015A is tricky to compensate, with 5 interacting controls.Only the LF comp and DC are needed for a stock probe that is just used on a new scope with different input cap. eg 15..22 pF.The HF comp is not needed unless it has been repaired or fiddled with.We used the 1kHz scope comp CAL out on out TEK 7904 which has a 40V output.Be careful with the ground return lead and the tiny different sized trimmer pots on the comp box.Bon ChanceJon

author: Lino22
author_rank: Newbie
timestamp: February 09, 2024, 02:06:50 pm
content: Thanks Jon, all i have is an old pulse generator that is really slow (80ns), then i have R&S RTB2002 which has a weak calibration output and also very slow (80ns), R&S SMT06 which has only modulatuon pulse, which is faster than the previous (about 30ns leading edge), but i would like a proper thing. 5ns, max 20ns.My scope is R&S RTB2002, which is very good and sufficient for the task. What i need is a calibration pulse, and that's what i am working on right now.

author: jonpaul
author_rank: Super Contributor
timestamp: February 10, 2024, 12:54:11 am
content: Hello: No fancy pulser or FETs needed.You can use a 50..500 DC PS and resistopr, pulse with just asnall fast relay, mains >>diode>>realy coilRuns like a vibratore.See TEK P6015A mauanl p. 2-5...2-10 for CAL proceeudureshttps://download.tek.com/manual/070822305.pdfBon chanc eJon
UCCM-LPQ SAMSUNG GPSDO board - Page 1
Forum section: electronics / beginners

author: ivo3510
author_rank: Contributor
timestamp: October 28, 2024, 07:42:36 pm
content: Hello,I've made a GPSDO in a box, with a linear PSU, and it works good, as far as I can tell, but I have issue with overheating.Below is the Ladyheather screenshot, could anyone please suggest if there is something wrong with the module?Perhaps, the OCXO is faulty, or maybe I should change something?The board is inside a closed steel box, with the PSU.Thank you!
uCurrent and clones question - Page 1
Forum section: electronics / beginners

author: Tj138waterboy
author_rank: Regular Contributor
timestamp: November 25, 2024, 12:35:38 am
content: I understand the principal of how the current amplification works but the question that I can't resolve is that if the resistance of your test leads or wires to the inputs of the uCurrent/clones add to the error budget especially in the .01 ohms range? Say you have crap China test leads that are .5 ohms or worse each.

author: ejeffrey
author_rank: Super Contributor
timestamp: November 25, 2024, 12:40:46 am
content: That's degrades the burden voltage but does not impact the current measurement accuracy.

author: Tj138waterboy
author_rank: Regular Contributor
timestamp: November 25, 2024, 01:59:00 am
content: Thats what my thoughts were leaning towards, thanks for the sanity check.
uCurrent Clone question - Page 1
Forum section: electronics / beginners

author: AndreyS
author_rank: Regular Contributor
timestamp: February 17, 2025, 05:16:58 pm
content: So I've got some uCurrent clone from my friend. And decided I want to build it. It differs from Dave's original basically by a cap on second stage opamp, additional resistor on resistor divider for virtual ground opamp (for I guess tweaking offset, I've read somewhere that resolution actually is between -1.5V to +1.0V) and 3 current sense resistors in series, see that schematic. Why there are 3 resistors in series?10mOhm 0.1% in 1206 nowhere to be even found. Only 0.25% is available.The only source for the given PCB I got I foundhere

author: Kleinstein
author_rank: Super Contributor
timestamp: February 17, 2025, 05:46:46 pm
content: No idea why they used 3 resistors in series. This will increase the gain by a factor of 3.There is another problem in the layout: it look like pins 3 an 7 and linked in the layout - this would defeat the use separate switches for the current and voltage sensing.The extra resistor at the virtual ground could make the usefull output range a bit more symmetric (like +-1.25 V instead of -1.5 to +1 V). It would not effect the offset. The same could be done with slightly different values. The extra resistor at the neg side would be the wrong direction or would need some -10 K. It could work with some 120 K for R12.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: February 17, 2025, 09:17:32 pm
content: Quote from: Kleinstein on February 17, 2025, 05:46:46 pmI modified my µCurrent Gold to allow switching between three different virtual ground offsets by changing the resistor divider ratio. See modification number 4:https://www.eevblog.com/forum/crowd-funded-projects/current-gold-on-kickstarter/msg448208/#msg448208

author: AndreyS
author_rank: Regular Contributor
timestamp: February 18, 2025, 08:41:03 am
content: Quote from: Kleinstein on February 17, 2025, 05:46:46 pmThank you. Now I'm considering of getting original PCB.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 18, 2025, 08:56:25 am
content: The PCB is not good, but one could still use bodges to kind of fix the layout issue and use only 1 out of the 3 shunts.
uCurrent Design choices - Page 1
Forum section: electronics / beginners

author: roogadget
author_rank: Contributor
timestamp: November 20, 2018, 11:25:32 am
content: Why are there these traces that go off to the side, they don't link anything.. (in yellow).I am trying to understand the reason behind this design choice.

author: mvs
author_rank: Frequent Contributor
timestamp: November 20, 2018, 11:35:56 am
content: Quote from: roogadget on November 20, 2018, 11:25:32 amThey are made for testing. Dave has made a video about it:
Ucurrent gold schematic questions - Page 1
Forum section: electronics / beginners

author: andymouse
author_rank: Contributor
timestamp: May 08, 2019, 11:02:40 am
content: HiA few questions about the ucurrent gold rev5 schematic, as I would like to build one, firstly the tps3809 appears to have pins 1,3 swapped over or am I reading it wrong (I have got data sheet)?The 0.1Uf caps on U1 and U2 are connected to -V whereas on the first device (Ucurrent) the caps where on the Ground, does this matter please?I am having trouble with the shunt resistors configuration as it seems R1 and R9 are in series and to be honest if this is correct and I am reading it wrong I will study harder! but please confirm schematic is correct, and I would very much like an explanation as the article describes the first revision and I got confused (Doh!)I would like these points explained to me before I buy all the parts. Thanks in advance.Andy
uCurrent Gold - trace to shunt resistors has no soldermask - Page 1
Forum section: electronics / beginners

author: mathews616
author_rank: Newbie
timestamp: January 12, 2020, 09:55:49 pm
content: I was going through the uCurrent project and noticed something that seemed unusual to me. In the image, the trace connecting R1 to the input jack is (a) of differing trace widths, and (b) has no solder mask for a small portion.Does anyone know if there's a reason for a small portion of the trace to be different from the rest? I can't think of an electrical reason, except maybe controlling the trace impedance with a different trace width but that doesn't explain why there's no solder mask. Is the exposed trace meant to help during testing?

author: floobydust
author_rank: Super Contributor
timestamp: January 12, 2020, 10:47:41 pm
content: PCB Rev. 5 - it's a 25 mil trace with 125 mil traces connecting to it. Makes no sense to me, I think it's a pcb layout error.

author: Dave
author_rank: Super Contributor
timestamp: January 13, 2020, 09:06:14 am
content: I think the idea behind it is to be a weak link in the circuit (a fuse). Although I doubt it would function as one, as the surrounding copper is likely going to suck the heat away way before it bursts.

author: SeanB
author_rank: Super Contributor
timestamp: January 13, 2020, 07:40:21 pm
content: Probably there to reduce heat coupling from the input leads to the sense resistor, and to act as a very poor fuse, if you plug it into a high current supply in parallel rather than in series.

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 13, 2020, 08:40:04 pm
content: Very likely a fuse. Even if it is an unintended one.

author: thm_w
author_rank: Super Contributor
timestamp: January 14, 2020, 12:19:36 am
content: Discussed here:https://www.eevblog.com/forum/oshw/current-gold-hw-design-question/Straight from the horses mouth.
uCurrent - Grounded output voltage - Page 1
Forum section: electronics / beginners

author: msperl
author_rank: Newbie
timestamp: February 19, 2015, 08:14:53 am
content: uCurrent Gold provides to Voltage output "floating" relative to VGround (so -CurrentIn + mV/uA if I remember correctly).So is there any means to normalize this versus my defined Ground for continuous measurements (with one of the new logicX that also can do analog measurements in parallel to the digital signal captures) and capture when doing "high-side" measurements?Low-side seems feasible, but means that the logic analyzer still has a lower ground than my circuit...High-side I could probably measure 2 channels (VGround/VOut- and VOut+) and calc the difference.I guess that some extra circuit would be needed if I want to avoid doing that...Any ideas/recommendations?Thanks, Martin
uCurrent Help! - Page 1
Forum section: electronics / beginners

author: notor
author_rank: Newbie
timestamp: March 23, 2013, 12:04:08 am
content: Hi everyone. I searched the forum but couldn't find out how to use my uCurrent. Can't find any information on the internet either. I'm a noob.I'm trying to measure my arduino's power consumption when it's sleeping. How do I set this up? Is the uCurrent even necessary?Anyone care to walk me through this? I don't want to break it.

author: Unknown
author_rank: Unknown
timestamp: March 23, 2013, 12:17:27 pm
content: I'm sure Dave showed this in an early video, and he also published the article describing the uCurrent on hiswebsite. Connect the voltage output jacks to a DMM in mV DC mode. Set the bottom switch to 1 mV/mA. Set the top switch to ON & BATT CHECK, and if the BATT OK LED lights (battery OK), set it to ON. Connect leads from the current input binding posts in series with the positive lead of the power supply to the Arduino. If it is fed from USB, this might require lifting a part on the PCB to interrupt the circuit. Make sure the positive terminal is closer to the power source, and the negative terminal is closer to the Arduino, otherwise you will get negative current values. The current has to come from a power source, via the positive terminal of the uCurrent, to the negative input terminal, and to the Arduino. Just like you would connect a DMM to measure current (I'm sure there are tons of instructions on how to do this).Turn on the Arduino. If the meter reads below 1 mV, set the switch to 1 mV / uA. If it is still below 1 mV, set to 1 mV / nA. You can now read the current from the DMM display.

author: notor
author_rank: Newbie
timestamp: March 23, 2013, 04:32:22 pm
content: Thank you sir!
uCurrent Tiny Trace - Page 1
Forum section: electronics / beginners

author: steve1515
author_rank: Regular Contributor
timestamp: September 19, 2019, 06:23:18 pm
content: I was looking at Dave's uCurrent PCB and noticed the small trace pictured below. It's located in the middle of a much larger trace coming from the negative input. I'm sure there must be a good reason, but I don't know why.Can anyone explain the reason why this was done?

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: September 19, 2019, 06:26:19 pm
content: I've never looked at the schematic but it could just be a little trace to link two ground planes together. Without the schematic it could be pretty much anything.

author: steve1515
author_rank: Regular Contributor
timestamp: September 19, 2019, 06:30:44 pm
content: Here's the schematic:http://www.eevblog.com/files/uCurrentRev5schematic.pdfI don't see any reason for the tiny trace to be there though. It's puzzling.

author: thm_w
author_rank: Super Contributor
timestamp: September 19, 2019, 11:20:44 pm
content: Quote from: steve1515 on September 19, 2019, 06:30:44 pmIts a PCB trace fuse. The idea is if you have it on mA range, and put 20A through it, that trace will blow up and the current sense resistor or other parts of the board will not be damaged.https://electronics.stackexchange.com/questions/200350/can-thin-sections-of-copper-traces-be-used-as-fuses

author: steve1515
author_rank: Regular Contributor
timestamp: September 19, 2019, 11:35:19 pm
content: Ah! That makes perfect sense!Thanks!

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: September 20, 2019, 05:54:56 am
content: I think it is also simply a form of net-tie. Simply looking at the schematic, you can see that there is a net label -IN at the negative input, and it is then connected to VGND. The only way you can do that is with some form of net tie in between.On second thought, it might not have to be a net tie. I think the 'net tie' is hidden in the (in my opinion) poorly drawn footprint of R1, which as 4-wire sense terminals.

author: thm_w
author_rank: Super Contributor
timestamp: September 20, 2019, 09:58:32 pm
content: Quote from: TheUnnamedNewbie on September 20, 2019, 05:54:56 amYeah since R1 is four pins they don't have to have the same net name, even if they are internally connected.Unless I'm missing something, its not poorly drawn, its fairly typical to do it like this.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 21, 2019, 09:55:10 am
content: I see 3 possible uses for this tiny thin spot:1) as a testing point for pogo-pins2) as possible point for an optional cut3) to get a better defined current distribution to the near by shunt resistor. So moving contact at the terminal would not effect the shunt value.Normally I would consider the normal length of the trace sufficient - so kind of overkill (but cheap) for this purpose.For a fuse the trace is still quite thick, and there are no protective diodes to really help the larger shunts to survive a high current.
uCurrent vs zero-resistance ammeter - Page 1
Forum section: electronics / beginners

author: Aleksolder
author_rank: Contributor
timestamp: October 07, 2014, 01:37:45 am
content: In all the discussion about the uCurrent, I find no mention of zero-resistance ammeters. What is it about zero-resistance ammeters that seemingly precludes them from this application?I've been using my uCurrent almost daily since it arrived a few weeks ago, and this thought only just ocurred to me, despite having installed thousands of ZRAs (evidently without much comprehension).

author: ConKbot
author_rank: Super Contributor
timestamp: October 07, 2014, 02:49:53 am
content: I havent heard the term ZRA before, however there is a current measuring device with zero effective resistance on the inputs. A transimpedance amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierappears to be the circuit level equivalent of the ZRA devices you mention. A voltage inverse of the burden voltage is applied to the resistor, keeping both input terminals at the same voltage, eliminating any burden voltage.Now nothing is perfect, and the GBP of the op-amp and the value of the gain resistor will end up appearing inductive as your frequency increases. (http://www.edn.com/electronics-blogs/the-signal/4398048/TIA-Input-Z--Infinite--or-Zero--What-is-it--really-)The main reason I see against TIA's in something like the uCurrent, is that forcing current across the feedback resistor will be current hungry, drawing just as much current as your circuit. So if youre measuring 10 mA, then your op-amp is burning 10mA x whatever your supply rail is in power. Not ideal for something coin cell powered.I havent used one, but a SMU may be able to perform a zero resistance current measurement if its compliance voltage was set at 0V? I'm not sure, perhaps someone who's used one can chime in.

author: robrenz
author_rank: Super Contributor
timestamp: October 07, 2014, 02:56:03 am
content: Quote from: ConKbot on October 07, 2014, 02:49:53 amThe 2450 SMU has <100µV burden voltage on current measurements

author: Aleksolder
author_rank: Contributor
timestamp: October 07, 2014, 04:04:06 am
content: To give some scale to the topic: Measured values with a ZRA are typically 5 to 25 uA DC. The ZRAs I used would run for about 90 minutes on 2 AA batteries (that's three months at six-hour awakening intervals), so yes, they are power-pigs.ZRAs are used in corrosion, and I can't see why they aren't used in micro-current DC electronics. DMMs inject current and voltage for other measurements, why not inject current to measure current?I don't recall the term TIA (I did read the references provided above), and I don't recall the circuit of the devices I installed.

author: Aleksolder
author_rank: Contributor
timestamp: October 07, 2014, 04:20:23 am
content: Here's an example ZRA circuit, simple enough even for me to mostly understand:http://kaktuscircuits.blogspot.hk/2014/05/zero-resistance-ammeter.html
UEFI? Worth going into?? - Page 1
Forum section: electronics / beginners

author: steamedhams
author_rank: Regular Contributor
timestamp: July 08, 2021, 01:33:45 pm
content: I have been looking for jobs in embedded and FPGA.I've seen a few jobs for BIOS/UEFI.What does a typical day look like for a BIOS/UEFI firmware engineer??

author: esepecesito
author_rank: Regular Contributor
timestamp: July 08, 2021, 02:30:03 pm
content: Disclaimer: I'm not working in BIOS/UEFI.But with 25 years as developer, I would say: it depends. Mostly on the size of the company. Big companies are bureaucracy machines. You will be most of the time filling reports, doing documentation, safety assessments, requirement management etc. And less than 20% actual coding.In small companies you will be doing 80%. For BIOS/UEFI I can imagine machine code work.From the question I estimate that it would be good for you to apply. For sure you will learn a lot of interesting stuff, that will help you to do better SW when you work in upper levels of abstraction.
Re: Question on oscilloscope signal caputre specifications - Page 1
Forum section: electronics / beginners

author: midnightvisions
author_rank: Contributor
timestamp: April 03, 2023, 10:01:30 am
content: Hello,I am building audio amplifiers, and looking to get into Class D amplifiers. All the TI chips, TPA3118 for example list transistor switching speeds in the nanosecond range. Switching power supplies also specify nanosecond timing for components.When I look for oscilloscopes that are compatible, I don't see any specifications that lists the fasted speed the scope can capture a signal.Question;What specification should I be looking at to see if the scope is capable of being used for my purpose?Cheers.

author: alm
author_rank: Super Contributor
timestamp: April 03, 2023, 10:40:31 am
content: If you need to validate those transition times, then look for a rise time that's say 1/5th of the transition time you're trying to measure. Also look for a sample rate that has a period substantially smaller than the transition time.This is if you want to actually measure those specifications. If you just want to use the device and want to see that there is a signal, you should be able to get away with more lenient specifications. Those fast switching times are probably to improve efficiency more than for any signal integrity reason.See pages 35-37 ofhttps://engineering.case.edu/lab/circuitslab/sites/engineering.case.edu.lab.circuitslab/files/docs/Oscilloscope_Fundamentals_-_Tektronix.pdf

author: BillyO
author_rank: Super Contributor
timestamp: April 03, 2023, 01:03:49 pm
content: The rise time response of a scope can be estimated by dividing it's bandwidth (BW) into .35. For instance, a 100MHz oscilloscope will have a minimum vertical rise time of about 3.5ns. This will be fine for looking at signals with rise times of about 20ns or more without doing any math. If you are not afraid of doing some math you can characterize signals as fast as the rise time of the scope to some reasonable accuracy.BTW, the folks at Tektronix claim modern optimized scopes should use .45, but I think that only really applies to scopes that cost more than cars.

author: WattsThat
author_rank: Frequent Contributor
timestamp: April 03, 2023, 01:21:07 pm
content: The amplifier chips control that timing, it’s not something you would need to measure.Any decent 100MHz digital scope is more than adequate for audio work as already explained. Be sure to watch Dave’s excellent video on how to NOT blow up your scope when working with mains connected devices.An important component for audio work is a low distortion signal generator. It doesn’t matter how good you output measurements are if you’re shoving distortion into the input side.

author: midnightvisions
author_rank: Contributor
timestamp: April 05, 2023, 09:29:44 am
content: Thanks gang!
UINT-T UTG962 showing jitter - Page 1
Forum section: electronics / beginners

author: ntoslinux
author_rank: Newbie
timestamp: October 10, 2022, 06:03:32 pm
content: Hi, I am a complete newbie to electronics and slowly experimenting with basic components. Recently I read about capacitors and wanted to see the charge/discharge graph in oscilloscope. So bought a UINT-T UTG962 function generator. But when I tried to capture the sin wave below is what I am seeing. I am not sure if the device is defective or am I missing something. The scope work perfect with it sample square wave signal. But from function generator, both square and Sin wave exhibits the follow jitter. Thanks

author: ataradov
author_rank: Super Contributor
timestamp: October 10, 2022, 06:30:13 pm
content: This is not jitter, this is just noise. You have 100 mVpp amplitude. And the signal on the scope is attenuated as well. It is hard to tell why without looking at the complete setup. I assume it is 10x probe.

author: ntoslinux
author_rank: Newbie
timestamp: October 10, 2022, 07:54:19 pm
content: Thanks Alex, after changing Amplitude to 1 volt it worked.

author: electr_peter
author_rank: Unknown
timestamp: October 10, 2022, 09:48:50 pm
content: Check if modulation is enabled. It can add noise (or other modulations)
UK equivalent of THHN cable? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 28, 2017, 01:56:00 am
content: What would be available in the UK that's the equivalent of #12 stranded THHN wire and #14 single core THHN wire please? Is there anything easily available? Thanks, it's for high power toroid winding and I don't want to veer away from the original if possible.

author: Monkeh
author_rank: Super Contributor
timestamp: January 28, 2017, 01:58:24 am
content: The closest equivalent I can think of is thin-walled automotive wire.

author: Cerebus
author_rank: Super Contributor
timestamp: January 28, 2017, 03:06:44 am
content: There isn't a direct equivalent that's in common use (common as in nip to the nearest electrical wholesaler and grab a drum). THHN designates a pvc sheath with a nylon over-sheath and while there are plenty of euro/uk equivalents in terms of stranding, cross-sectional area and temperature rating there isn't a common one that I know of with the nylon over-sheath. Consequently if you use common equivalents you're going to end up with a higher outside diameter.For instance, 12 AWG stranded THHN (3.31mm2CSA) - OD ~ 3.29mm, nearest equivalent 4.0mm2CSA 6491X (aka H07V-R) - OD ~4.2mm.For your 14 AWG (2.08mm2CSA) the nearest equivalent is going to be 2.5mm2CSA H07V-U.THHN is specified for both wet and dry conditions. 6491X is only specified for dry conditions. THHN and 6491X are both common as muck in their respective countries and are on the shelves of every electrical factors/wholesalers.
UK Samsung charger query - Page 1
Forum section: electronics / beginners

author: fizzbang
author_rank: Newbie
timestamp: December 11, 2018, 12:04:35 am
content: Using this light >https://www.toolstation.com/shop/Lighting/d220/Solar+Lighting/sd3468/Luceco+SOLAR+Guardian+1.5W+PIR+Wall+Light+IP65/p55970Solar panel / battery couldn't keep up with power demand due to trees triggering PIR & shading solar, so disconnected solar/ ~3.8v battery pack and connected a 230v AC > 5.0v/0.7A DC samsung phone charger to the PCB via a 4m lead.Plugged it in my house and it functions as expected.Took it next door, plugged it in, no dice. Tried various different sockets, no joy. Checked voltage next door 245v - same as my house. Probed output from samsung charger with basic DMM and confirmed 5.01v showing.Tried it in two other houses in the same road and it works (all houses built same time to supposedly the same electrical standards).Every other device in the affected house functions absolutely fine.Any suggestions please as to why it won't work in this one particular house?
Uknown MELF Component - Page 1
Forum section: electronics / beginners

author: dk-001
author_rank: Newbie
timestamp: September 30, 2020, 10:02:59 am
content: Hi,Would anyone can help me to identify the MELF component in the attached picture? It is laid out with capacitors at the end of a power supply channel output. I'm inclined to say that it is a resistor (forming RC filter) but since there are no color rings I'm also hesitant.Thanks...

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 30, 2020, 12:32:27 pm
content: Hi,I bet also it's capacitornope, it must be a metal film resistor, maybe for discharge?

author: Jwillis
author_rank: Super Contributor
timestamp: September 30, 2020, 08:21:50 pm
content: Can you sketch the part of the circuit where it is in relation to surrounding components ? Does it exhibit a measurable resistance . It could just be a jumper . Does it show continuity one way but not the other . Could be a diode . Does the resistance climb to infinite with DMM attached . It could be a capacitor .
ULIS 384 changing to different output - Page 1
Forum section: electronics / beginners

author: minicodcraft
author_rank: Newbie
timestamp: June 15, 2023, 03:51:15 am
content: I am not sure if this is the right place to ask this question but I have seen a few posts about this same sensor and wanted to see if I could get some help. I recently bought a ULIS 384 for a project I wanted to work on. It was originally supposed to be a simple comp sci project but it has turned a bit more complicated. the thermal camera has two outputs: are a small coax cable, and a mini USB. My question was if I am able to change out this top PCB for one with just a USB or some other video output since having the coax as the output is troublesome. attached are the top 2 PCBs. since I am very new to working with this sort of thing(my only knowledge is searching this forum during this project) I'm not even sure what the connecter on the second board is. Any help would be appreciated. Please ask if any clarification is needed. Thank you.
ULN2003A and piezo buzzer - Page 1
Forum section: electronics / beginners

author: kirill578
author_rank: Newbie
timestamp: February 18, 2012, 12:03:47 pm
content: Hey, I'm using an AT89S52 which has internal pull-up resistor on all its port(according to the datasheet).When I attempt to control LEDs attached to ULN2003A it work perfectly.however,when I connect a piezo buzzer it doesn't work unless I connect a pull up resistor (I used 10Kohm) to the input of the ULN2003A.As far as I understand the ULN is the one which sicks the current from the piezo buzzer, with an open-collector input.Basically, my question is why an external pull up resistor required just for the buzzer?I've attached the internal circuit of the device.

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 18, 2012, 12:34:54 pm
content: So are you driving the input of the ULN2003A by setting the pin as an output and setting it high? Or are you just setting the pin as an input and relying on the pull-up resistor?The pin's pull-up resistor is likely in the 47k range so it is probably just too weak. Anyway, you should be using the pin as an output and outputting a high to drive the ULN2003A, in which case the pull-up doesn't come into play at all.

author: westfw
author_rank: Super Contributor
timestamp: February 18, 2012, 10:31:46 pm
content: QuoteAccording to the datasheet, port 0 only has pullups when it's used to drive external memory. Otherwise it's sink-only open-drain...

author: kirill578
author_rank: Newbie
timestamp: February 19, 2012, 04:04:58 pm
content: Fair enough, It can seek current only. But how does it work perfectly with the LEDs?By the way, I've checked the datasheet once again. and it's exactly the opposite:"Port 0 is an 8-bit open drain bidirectional I/O port....When 1s are written to port 0 pins, the pins can be used as high-impedance""Port 1 is an 8-bit bidirectional I/O port with internal pull-ups.""Port 2 is an 8-bit bidirectional I/O port with internal pull-ups.""Port 3 is an 8-bit bidirectional I/O port with internal pull-ups."http://www.atmel.com/Images/doc1919.pdfI've found the reason:the current the LEDs draws is about 10mA while the buzzer draw much more(due to its low resistance). The internal circuitry of the ULN2003 as a darlington transistor with certain gain.thus, we can understand that the input current is enough to drive an led but not a buzzer, so we add another pull up so the gain current will be enough to drive it
ULN2004AG - Page 1
Forum section: electronics / beginners

author: kfc_n
author_rank: Contributor
timestamp: November 03, 2014, 01:58:45 am
content: Dear Friends,Does someone here have experienced using a ULN2004AG for solenoid control? It is making my life miserable now..

author: kfc_n
author_rank: Contributor
timestamp: November 03, 2014, 02:15:08 am
content: Does anyone know the proper wiring from input to output? thanks

author: sleemanj
author_rank: Super Contributor
timestamp: November 03, 2014, 04:15:48 am
content: The ULN2004 is just a darlington array.I could hazard a guess you are confused by the COM pin, this is the "free wheeling diode", aka, back-emf diode, connect it to POSITIVE.A HIGH signal on one of the inputs, will connect the corresponding "output" to ground.

author: KerryW
author_rank: Regular Contributor
timestamp: November 03, 2014, 04:18:38 am
content: Pin 8 is ground. Pin 9 is the clamp diodes, tie to solenoid voltage.1,2,3,4,5,6 & 7 are inputs.16,15,14,13,12,11 & 10 are the outputs, tie to 1 side of each solenoid.Tie the other side of each solenoid to solenoid voltage.Note that the ULN2004 is intended for 4000 series CMOS logic level input (12-15V), whereas the ULN2003 is intended for 5V logic input. That may be causing your problems.

author: kfc_n
author_rank: Contributor
timestamp: November 05, 2014, 05:54:30 am
content: Can it be used as a solenoid/motor driver?

author: Paul Moir
author_rank: Frequent Contributor
timestamp: November 05, 2014, 06:13:19 am
content: Well, that's what it's designed to do...What solenoid/motor are you driving? What with? What are you trying to do?
Help designing first PCB: Power-distribution - Page 1
Forum section: electronics / beginners

author: Electabuzz
author_rank: Newbie
timestamp: July 25, 2020, 11:25:07 am
content: Hey guys, complete newbie to the electronics game hereI’ve recently started/tried designing a PCB. I saw Dave’s latest video and figured, let’s give the forum a go to try and gather some feedback on it! I’m still confused by the simplest of things like resistors and diodes, so it would be great if you guys could help me with a sanity check.My problem: I want to upgrade a 3D-printer (Ultimaker 2) with a new mainboard. The original board has a power-connector, power-switch and USB-connector directly on it. That makes a drop-in-replacement board hard. To be able to use any board I like, now and in the future, I need a very simple PCB to work with these components and adapt them to simple connectors so I can run wires for power and USB wherever.This is the original board:Visual:https://raw.githubusercontent.com/Ultimaker/Ultimaker2/master/1091_Main_board_v2.1.1_(x1)/B1091-B2P-C.pdfPCB & schematic:https://raw.githubusercontent.com/Ultimaker/Ultimaker2/master/1091_Main_board_v2.1.1_(x1)/Main%20Board%20V2.1.1.pdfFor my PCB:FUNCTIONALITYGrab the DC-power from the 4-pin DIN-connector, split that over two positive and two negative screw-terminals. Interrupt this power with the use of a switch. The power input is a 220W 24V adapter, about 10A.USB-passthrough, adapt USB-B to USB-A.SCHEMATICSee attachments.BOM / parts-usedDC-connector (KPJX-4S-S)Power-switch (YUEN FUNG SR-1-102-C03-0003-RS) equivalent to:https://docs.rs-online.com/77e1/0900766b815875bb.pdf24V 10A Relay (TE Connectivity 6-1419128-6) datasheet:https://datasheet.lcsc.com/szlcsc/1912111437_TE-Connectivity-6-1419128-6_C305882.pdfSingle row barrier-terminal, 4-contact 8.25mm-pitch (WJ35S-B-8.25-4P)Uninteresting USB-connectorsPCB SPECS2 layers1.6mm thickness1 oz copper weightPCB-designSee attachments.Board Size: 79x30mmTrack width: 0.5mm and 6mm.Red = top (GND-plane)Blue = bottomYellow = top silkscreenGreen = bottom silkscreenReally curious what you think of my design!There's some struggles I’ve got myself already, which are:- Are normal plated holes enough to handle the current from the power-connector? The original board uses some kind of rivets in its design. I can't find anything about current handling capabilities for holes, so maybe it's just fine like this.- Are 6mm 1oz copper layers enough to carry 10A of current? I found some calculators online, but they are all over the place. They could be upped to about 8/8.5mm without issue, but wider probabably isn't always better?- The traces to and from my power switch are long and slither to both ends of the board. Problem?- Should the USB-shields be connected to GND? I'm finding mixed anwers, ranging from yes to let if float, connect to GND with a resistor in between..- I don’t think I need resistors, caps or diodes anywhere? Maybe something between the switch and relay-coil, for “smoothly” handling switching on/off? Or discharging the relay-coil?Haha, hope I didn't give an overload of questions. Thanks for any help!
Ultra low power clock generator for portable devices - Page 1
Forum section: electronics / beginners

author: DanioIO
author_rank: Contributor
timestamp: September 25, 2014, 02:07:41 am
content: Hi,Im trying to make a simple mp3 player based on ADAU1761 DSP Audio Codec, but i stopped at a small problem, this ic requires a clock generator, but i checked so manufacturers and they consider 4mA as a low power clock generator. I can not used 4mA for a clock, is there a lower current solution? I need a clock in 8-27MHz range.Example low power oscillator:http://www.sitime.com/products/datasheets/sit8008/SiT8008-datasheet.pdfADAU1761 datasheet:http://www.analog.com/static/imported-files/data_sheets/ADAU1761.pdf

author: Marco
author_rank: Super Contributor
timestamp: September 25, 2014, 03:35:19 am
content: Bit of googling for low voltage/current oscillators finds theASD seriesfrom Abracon and theHK seriesfrom Mercury Crystal.That said, why is it so important? Even driving in ear headphones are going to make it pretty much irrelevant.

author: DanioIO
author_rank: Contributor
timestamp: September 25, 2014, 11:22:56 am
content: I found an 0.7mA solution, can i get even lower current? The 0.7mA i can achieved using a LTC6930-8.00 oscillator.I need a low power solution for standby mode, in which i the main IC will running consuming about 7-10mA.LTC6930 (http://cds.linear.com/docs/en/datasheet/6930fd.pdf).

author: Marco
author_rank: Super Contributor
timestamp: September 25, 2014, 12:18:05 pm
content: What's the boot time of your device? Can't you just power gate everything with a small micro (using the internal RC oscillator) and a FET?PS. although I doubt it matters, a 12.288 MHz oscillator will give you the cleanest clock.