hybridfree/eevblog-posts huggingface dataset:
locating datasheet on chip - Page 1
Forum section: electronics / beginners

author: vodoings
author_rank: Newbie
timestamp: October 20, 2013, 11:54:37 am
content: HelloI'm having a bit of trouble locating a datasheet on an chip (see attached picture)I have tried all the usual datasheet sites I knowAny help is greatly appreciatedResized image

author: tszaboo
author_rank: Super Contributor
timestamp: October 20, 2013, 12:05:24 pm
content: That is probably a custom made thin/thick film passive component, specially made for some kind of equipment, by the looks of it.Where did it came from?

author: vodoings
author_rank: Newbie
timestamp: October 20, 2013, 01:07:35 pm
content: I got it from a co worker pretty sure he said it was a double optocoupler because I needed one at the moment (awhile ago) but I can't remember the pin outs that he told me,I think it comes from an power supply to a radar in an boeing 737 but I'm not sure

author: Rory
author_rank: Frequent Contributor
timestamp: October 20, 2013, 03:53:53 pm
content: Only 8 pins, a dual optoisolator. A few minutes with a DMM and you should be able to determine which are the LED pins and which are the phototransistor C-E/S-D outputs. Ask how if you can't figure it out for yourself.

author: vodoings
author_rank: Newbie
timestamp: October 20, 2013, 06:00:15 pm
content: I'm an electronics mechanic with 3 years experience I know how to use my dmmI just didn't know where else to post my threadAnyways here's some readings.Pin 1 (÷) pin 3 (+) = diodePin 2 (+) pin 4 (÷) = diodePin 5 (÷) pin 7 (+) = diodePin 6 (+) pin 8 (÷) = diodeAny other combination gave overload both in ohm and diode readingWhat I'm more interested in is the specs on the chip

author: Rory
author_rank: Frequent Contributor
timestamp: October 20, 2013, 07:13:08 pm
content: Sincerely doubt you will find a datasheet on a proprietary part like this. Maybe from Collins or Bendix/King if it's from an avionics radar as you say. So it's pretty much up to you to reverse-engineer the device if you want to get any use out of it. Otherwise it should go in the junk drawer and move on with something else.Through simple reverse engineering techniques you obtain just about every device parameter necessary for use except for the ones determined through destructive testing, like breakdown voltages and maximum current/device dissipation.

author: ConKbot
author_rank: Super Contributor
timestamp: October 21, 2013, 01:40:21 am
content: Look at the forward voltages of the diodes, the ones with a higher Vf are likely the LEDs. A meter would probably read ~1.5V, but if you use a 5mA constant current source, expect more like 2.3-2.8V for red LEDs. The photodiodes are likely plain silicon, so expect a 0.7(ish) forward voltage)given that its a photodiode instead of a phototransistor, I'd expect it to be a decently high-speed optoisolator.

author: vodoings
author_rank: Newbie
timestamp: October 21, 2013, 02:37:36 pm
content: The forward voltage is the same on them all so it might be an 4 way rectifier but I havent checked with an power supply and oscilloscopeAnd I was mostly interested if anyone could help me in finding a datasheet on the chip
Locating parts - Page 1
Forum section: electronics / beginners

author: gmaslin
author_rank: Newbie
timestamp: November 11, 2016, 04:01:25 pm
content: I am looking for a search engine by spec. the idea is to find parts by specific parameters. I know some manufacturers have this for their own products but has anyone found one that is vendor agnostic? For example, I need a short list of complimentary bipolars with hFe>500. Where do I get this?

author: TinkerGDS
author_rank: Contributor
timestamp: November 11, 2016, 04:12:49 pm
content: I am by no means an expert in the EE field, but, I've found Mouser and Digi-Key to have great parts filters. I prefer Mouser, but that's my own preference. I do use Digi-Key as a second source.

author: Cliff Matthews
author_rank: Unknown
timestamp: November 11, 2016, 04:27:13 pm
content: http://alltransistors.com/There is ads, but I find something like the "uBlock" browser add-in makes this less obnoxious.

author: gmaslin
author_rank: Newbie
timestamp: November 11, 2016, 05:17:42 pm
content: Thanks guys. How successful am I likely to be asking for a matched set in the wanted section?

author: gmaslin
author_rank: Newbie
timestamp: November 11, 2016, 11:17:26 pm
content: Dearest Wilfred, that was the ticket, thanks!
locking for crimp on terminal/pin (used at an android car radio) - Page 1
Forum section: electronics / beginners

author: littleMax
author_rank: Contributor
timestamp: December 02, 2020, 09:58:29 pm
content: Hello everybody,i want to modify the wirering harness of my car stereo/radio. It is a unit from Pumpkin and i installed it in my Mercedes Benz W245 (2006). The radio has multiple connectors, for example for AUX-in and i want to make an adapter to connect it to the quad lock plug of the car.Just so you understand what i want to do:Black is everything what is allready there, i want to ad the orange cables.Example: My car allready has an AUX in socket and i want to connect the sockets at the quadlock with the pins ate accessories connectorsIn the attchments are pictures of the sockets that im searching. They are similare to the MQS (in pin sice) system from TE, but much longer from latch to the end. Im also locking for the male pins for this.Those anybody know these, looked at mouser.... but... yeah two many options

author: m k
author_rank: Super Contributor
timestamp: December 04, 2020, 09:54:08 am
content: You're in the homeland, get spares from the surplus yard and modify their wires.

author: littleMax
author_rank: Contributor
timestamp: December 04, 2020, 01:38:49 pm
content: Would be possible with the end at the accessories connector. But i still have no male pins for the quadlock connector they use. Maybe i need to buy a complet quadlock adapter harness....
log opamp question  - Page 1
Forum section: electronics / beginners

author: electronics man
author_rank: Frequent Contributor
timestamp: February 02, 2014, 05:19:27 pm
content: I have been experimenting with log opamp circuits. the equation is Vout = K ln (Vin/Vref). I am confused as to what k is and Vref is can someone help? i am using the standerd opamp with a diode in the feed back loop of an opamp.

author: Rory
author_rank: Frequent Contributor
timestamp: February 02, 2014, 05:22:51 pm
content: http://en.wikipedia.org/wiki/Log_amplifier

author: electronics man
author_rank: Frequent Contributor
timestamp: February 02, 2014, 05:24:58 pm
content: I looked it doesnt explain much

author: electronics man
author_rank: Frequent Contributor
timestamp: February 02, 2014, 05:59:49 pm
content: All it does is say what it is not explain it

author: Rudane
author_rank: Regular Contributor
timestamp: February 02, 2014, 06:39:27 pm
content: electronics man: Follow the first link in external references and scroll down to the section around equations 5 and 6. Look at the two equations and deduce what K must be from them.

author: Rory
author_rank: Frequent Contributor
timestamp: February 02, 2014, 07:11:38 pm
content: Sorry I was terse, didn't have time to make a long-winded explanation. To further confuse you, and instead of spoon feeding you information I could possibly get wrong, here is acrediblesource for you to study.Analog Device's Log Amp Basics tutorial.http://www.analog.com/static/imported-files/tutorials/MT-077.pdfGo to page 4 for the diode log amp.The point is, sharpen your Google-Fu. Research it for yourself from manufacturer's data sheets, appnotes and tutorials instead of asking on a forum where some pendantic know-it-all can give you the wrong answer.
Logic 2 or Pulse View - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: March 08, 2024, 12:03:32 am
content: Hello people, I have a Chinese 8-channel logic analyzer, one of the cheap ones, and I usually use it with the Logic 2 software from Saleae, or sometimes with the pulse view, but due to my ignorance, I never knew which of the software is better and because, since I only use it with small arduino projects and other micros, Spi, I2c, UART etc. I would really appreciate knowing the difference if there is between pulse view and the latest one in Logic 2?in spanishhola gente, tengo un analizador ligico chino de 8 canales, de los baratos, y lo suelo usar con el software Logic 2 de saleae, o a veces con el pulse view, pero debido a mi ignorancia, nunca supe cual de los sofware es mejor y porque, ya que solo lo uso con pequeños proyecto de arduino y otros micros, Spi, I2c, UART etc. Agradeceria mucho saber la diferencia si la hay en tre pulse view y la ultima de Logic 2?

author: BennoG
author_rank: Frequent Contributor
timestamp: March 08, 2024, 08:32:44 pm
content: it highly depends on what you find the easiest to work with.And sometimes 1 program has a feature you need, than you use that program.I mainly use picoscope (I yave 3 of them) seaware, but also use pulseview when using the SDK because the pulseview file format is open and the picoscope file format is closed.Benno
Logic analyser query - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: March 01, 2015, 07:20:32 pm
content: HiI've got my basic 6502 system running but as I don't have any I/O, I've just been confirming that code is being run by capturing D0 to D7, triggered on a D0 edge. The code runs a very simple loop. The address decoding outputs look as good as they can do with a logic probe and capturing the data bus mostly looks ok. The stream of data looks pretty good and mostly follows the hex code from the ROM. However, there are odd glitches where there's an extra high bit in a byte, quickly followed by the correct byte. The specific bit varies. I'm speculating that this is because unlike the system itself where control lines are used to signal valid data on the bus, I'm just grabbing the data as fast as I can and the buffered data lines may not all be quite ready at the sample points. Does this sound reasonable ?The CPU clock is 3MHz and I've been sampling up to 24MHz.I think that if things were actually running bad inside the system, the code (and sampled data) would be all over the place but the loop itself is maintained.Thanks

author: SeanB
author_rank: Super Contributor
timestamp: March 01, 2015, 08:40:02 pm
content: That would be sampling errors. Change the trigger edge to whatever the 6502 uses and it will be stable.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: March 01, 2015, 08:54:32 pm
content: Thanks Sean. I think that you've probably confirmed my theory.As I've only got eight channels in the analyser, I'm having to to trigger on one of those bits. So, it's a rise on D0. Not perfect but probably good enough for me to know that I can add the next stage, which is the proper I/O.

author: DJohn
author_rank: Regular Contributor
timestamp: March 03, 2015, 01:34:36 pm
content: The data lines won't all change at exactly the same time, so yes, that's your problem.It might be better to look at half of the data bus at a time. Keep one channel on the clock, one on a signal that will indicate the start of your loop (when I'm bringing up a 6502, I put the start of the loop at an address ending in 1ff, and don't access anything else at an address with bit 8 high. Then I can use the falling edge of A8 as a loop trigger). Capture D0-D3, then D4-D7 in another pass. That leaves a couple of channels for part of the address, or R/W.It's possible to do this with a 2 channel scope with external trigger and a bit of patience.

author: Howardlong
author_rank: Super Contributor
timestamp: March 03, 2015, 02:57:09 pm
content: Back in the 70s, on the odd occasion we had access to a scope, we probed one bit at a time with a piece of paper and a pen. Painful, but we learned how to speak binary!
logic analyzer literature - Page 1
Forum section: electronics / beginners

author: gkmaia
author_rank: Frequent Contributor
timestamp: April 03, 2019, 08:57:00 pm
content: Hi, I am looking for a good book about how to take the most out a logic analyzer main principles.Learn things like:- threshold for different logics- external clock- word triggering- glitch triggering- etc...Is there such thing?

author: Stray Electron
author_rank: Super Contributor
timestamp: April 03, 2019, 10:09:00 pm
content: Look up HP's Application Notes.

author: TK
author_rank: Super Contributor
timestamp: April 03, 2019, 11:21:35 pm
content: Take into consideration that most of modern logic analyzers (saleae, saleae clones, etc) are protocol analyzers and some don't even have external clock input for state analysis. Zeroplus logic analyzers have external clock input. For serious parallel bus analysis, you need to get one of the vintage HP / Agilent / Tektronix logic analyzers like the Agilent 1670E, 1670G, 1680, etc. They offer a bunch of input ports including external clock, high sample rate, a lot of capture memory and some serious triggering capabilities.

author: TK
author_rank: Super Contributor
timestamp: April 03, 2019, 11:23:53 pm
content: https://literature.cdn.keysight.com/litweb/pdf/E2433-97038.pdf?id=1000001904-1:epsg:man
Logic Analyzer Probe Impedance Matching Issue - Page 1
Forum section: electronics / beginners

author: hjups
author_rank: Newbie
timestamp: February 17, 2016, 05:23:02 am
content: Hi all,For the past few weeks I have been working on designing a logic analyzer (for fun). My plan is to use ADCMP562s to do edge triggering, and then send the result off to an FPGA (a Dev board for now) to handle the data capturing.I am stuck on the circuitry that precedes the ADCMP562s. I ended up buying an HP/Agilent/Keysight logic probe pod (16 probes on a 40 pin IDC), and a 40 pin twisted wire, controlled impedance cable. I figured that connecting the probes directly to the cable and ending with an impedance matched resistor would work (followed by ESD and current limiting protection). I was expecting to see an attenuated version of the input signal when I tested the setup with a 4 MHz square wave , but instead ended up with positive and negative spikes corresponding to the rising and falling edges of the test signal, respectively. I was able to reproduce this result in LTSPICE using the equivalent circuit that Keysight provides in their documentation.I am at a loss as to what is going wrong / how to fix it. Or is this actually the intended result from the logic probe, to easily capture rising and falling edges? If so, what would be the best way to set up triggering with the ADCMP562?It should be noted that the test signal comes out clean if I remove the controlled impedance cable and connect the oscilloscope directly to the output of the logic probe. I have also attached the equivalent SPICE circuit and simulation result (with the probe at the location: Ch2).Thanks in advance.
Logic Analyzer probes for SMD - Page 1
Forum section: electronics / beginners

author: obiwanjacobi
author_rank: Super Contributor
timestamp: March 18, 2015, 09:45:49 am
content: I am looking for a (the easiest) way to attach multiple logic analyzer probes (inputs) to a(ny) smd PCB that is under test/repair.I know of the bed of nails technique/idea, but the boards are different every time and as exploration of the PCB/schematic advances so will the test points I require to measure. So I need something that is really flexible.I thought of using the individual bed-of-nails pins but what would be a good way to fix them into position? 3rd hand alligator clips are to flimsy and do not keep my (normal) probes in place...I cannot hold the by hand because I need those to trigger test scenarios and work the computer...Any ideas are most welcome.Marc

author: alank2
author_rank: Super Contributor
timestamp: March 18, 2015, 01:41:53 pm
content: There was a guy who had a kickstarter here for brackets and pins for soldering that I would think could also be used for this task.I've got the XKM grabbers that came with my Saleae unit that are pretty small but then again so are smd pins. You can get them on eBay for a pretty good price if you search a bit.Search for hp agilent 5090-4356 on ebay there are a lot of 20 packs.Good luck!
Logic Analyzers real freq. and measured freq. - Page 1
Forum section: electronics / beginners

author: Yaro
author_rank: Contributor
timestamp: April 27, 2015, 09:28:15 am
content: Hi all,I've a question about logic analyzers and sample frequencies.For example:I've a logic analyzer that have a sample rate of 200Mhz.I've a 20 Mhz clock(50% duty cycle) to sample and I've measured 16Mhz clock and sometimes 20Mhz clock when I sample this signal.In the case I've a 50Mhz(50% duty cycle) clock to sample and a 100Mhz(50% duty cycle) clock to sample, I've measured respectively a 10/11Mhz clock and 15/20Mhz clock. In which of this two case I loose data(can't sample a logic 1 state for example) and how I can determinate relationship between sample clock, signal clock to sample and clock I get?

author: pcblearner
author_rank: Contributor
timestamp: April 27, 2015, 12:56:42 pm
content: Can you check on an oscilloscope to see if you actually are getting 20/50/100MHz from the clocks?It sounds like perhaps the logic analyzer is not configured for your circuit; I would double check the signal HI/LO levels you are using match what the analyzer expects, and also check if there is a prescaler enabled that could be dividing the clock input.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: April 27, 2015, 01:09:06 pm
content: What logic analyzer are you using?

author: free_electron
author_rank: Super Contributor
timestamp: April 28, 2015, 11:49:10 pm
content: could be, as there is no phase relation between your clock and the sampling point of the LA.you will need to set up the analyser to trigger from this clock and then run the analyzer. so if the frequencies perfectly align you should get 5 samples high and 5 samples low a 20MHz clock sampled at 200MHz gives you a max of 10 samples.if there is the slightest phase shift or the clock is off ( 19.9999 MHz ) you will get 5 samples high and 6 samples low. in this case the analyzer will give you 1/5 error. 1.5 of 20 is 4MHz .. so it will tel you 16 MHz ... if oyu feed it 20.000001 it will tell you 20 MHz.Sampling a 50Mhz clock at 200 MHz hives you 4 samples. be 1 sample off and you drop 1/4
logic analyzers sample rate - Page 1
Forum section: electronics / beginners

author: clkaczor
author_rank: Contributor
timestamp: February 11, 2015, 04:11:50 pm
content: I was wondering when you have a logic analyzer say 8 channels and a max sample rate of 250 MS/s is the sample rate split between all the channels like it is on an oscilloscope?

author: Rigby
author_rank: Super Contributor
timestamp: February 11, 2015, 04:29:27 pm
content: Depends on the specific hardware. Usually, it's split, though, in my limited experience.

author: free_electron
author_rank: Super Contributor
timestamp: February 11, 2015, 06:59:04 pm
content: on a real logic analyser most of the time it is on all channels simultaneously. unless explicitly stated that it is for half channel or quarter channel only.Agilent typically will stat it like this :4Mp / 1Gss 8Mp / 2Gss half channel
Logic and Latching Help Needed - Page 1
Forum section: electronics / beginners

author: kmossman
author_rank: Contributor
timestamp: August 28, 2016, 01:12:48 pm
content: Using LS or CMOSI need a latch to work as follows1) two inputs, one output2) upon a short '1' on input_1, output goes high3) upon a short '1' on input_2, output goes low. But any other logical highs do not affect the outputideas?

author: ludzinc
author_rank: Unknown
timestamp: August 28, 2016, 01:23:03 pm
content: Quote from: kmossman on August 28, 2016, 01:12:48 pmCheck out a SR Flip Flop.

author: David Hess
author_rank: Super Contributor
timestamp: August 28, 2016, 09:11:35 pm
content: In case that is not clear, SR flip-flop = set/reset flip-flop.A set/reset latch made from a pair of NOR or NAND gates will also work.https://en.wikipedia.org/wiki/Flip-flop_(electronics)

author: Ian.M
author_rank: Super Contributor
timestamp: August 28, 2016, 09:30:31 pm
content: "But any other logical highs do not affect the output" may be a problem. If both the S-R flip-flop's S and R inputs are high, both its Q and /Q outputs will be low and its final state will depend on which input goes low first.Also it doesn't distinguish between "short" and any other length pulses.

author: David Hess
author_rank: Super Contributor
timestamp: August 28, 2016, 10:42:29 pm
content: So RC couple the signals into the set and reset inputs and then the flip-flop will only react once to the last positive signal edge. Beyond that, use edge clocked flip-flops or add some additional logic.
Logic Chip Drawing Stencil / Template UK - Page 1
Forum section: electronics / beginners

author: Markybhoy
author_rank: Regular Contributor
timestamp: June 05, 2015, 03:03:55 pm
content: Hi,Im looking for a plastic template for drawing simple logic chips on paper And Nand Not etc..I was wondering if anyone could recommend one, or maybe some kind of plastic ruler with the cutouts for drawing.It looks like rs used to sell them but seems they are discontinued.http://uk.rs-online.com/web/p/stencils/3298503/

author: lapm
author_rank: Frequent Contributor
timestamp: June 05, 2015, 03:44:36 pm
content: Well depending on standard you want to follow in your drawings they are easy..http://en.wikipedia.org/wiki/Logic_gate

author: Electroplated
author_rank: Regular Contributor
timestamp: June 05, 2015, 11:23:29 pm
content: Have a look here :Electrical and Electronic Installation Symbols Drawing Template Stencilhttp://www.amazon.co.uk/gp/product/B003QTGTDO?*Version*=1&*entries*=0I have one of the blue older types made by Helix but its from the 90's so not sure if its still made by that company.

author: Silveruser
author_rank: Regular Contributor
timestamp: June 05, 2015, 11:45:39 pm
content: RapiDesig, Staedtler-Mars those are two names I dug out of the very bottom of my drawer.

author: Markybhoy
author_rank: Regular Contributor
timestamp: June 06, 2015, 10:45:06 am
content: Thanks I'll have a look at those Amazon ones.

author: bingo600
author_rank: Super Contributor
timestamp: June 06, 2015, 11:32:07 am
content: I have some Linex templates, but don't know if they're discontinuedIe. 1139S Logic Template . pg34arifa.myvigo.co/master/download_files/Linex-Main-Catalogue-GB-1.pdf/Bingo

author: zapta
author_rank: Super Contributor
timestamp: June 06, 2015, 12:05:53 pm
content: Three days you can order whatever you want, custom laser cut.
Logic circuit to detect loss of voltage - Page 1
Forum section: electronics / beginners

author: iamnothim
author_rank: Regular Contributor
timestamp: April 25, 2013, 02:40:05 am
content: In my tube tester project 2 out of 3 tests operate. the 3rd is the "Shorts Test"An indicator light T3 1/4 90V should come on when one of the pins of the tube under test has a short. In the test circuit there are 6 pins bussed together, if the buss breaks the light should go on without pushing any buttons. The bulb is good.This got me thinking. Is there a little logic component that could monitor for loss of voltage and close a contact, illuminating a light / LED?I suspect I would have to bring the voltage way down.I'm barely able to work with resistors and capacitors. I have no idea how to program and implement something like that but I think it would be more reliable solution.Any comments or direction will be appreciated.Thanks

author: jpb
author_rank: Super Contributor
timestamp: April 25, 2013, 10:21:05 am
content: why not just use a relay? Assuming you want it to operate at 90V and you want it to detect a complete loss of voltage.Otherwise you could use a resistive divider and a comparator with some other fixed voltage (if the fixed voltage was also 90V you wouldn't need the divider).Or perhaps a bit more fun would be an electromagnet, a hammer and a big switch

author: Gall
author_rank: Frequent Contributor
timestamp: April 25, 2013, 10:54:27 am
content: For higher voltage, one of many good solutions is resistive divider with an optocoupler.For lower viltage, just a divider driving a transistor or a logic gate.

author: iamnothim
author_rank: Regular Contributor
timestamp: April 25, 2013, 03:44:03 pm
content: Thanks for the ideas.The hammer is a must have, but not for the circuit.
logic ics for above 100 MHz operation - Page 1
Forum section: electronics / beginners

author: txx4488
author_rank: Contributor
timestamp: December 21, 2018, 02:21:38 pm
content: which are logic ics for or above 100 MHz operation ?

author: mvs
author_rank: Frequent Contributor
timestamp: December 21, 2018, 03:06:38 pm
content: Quote from: txx4488 on December 21, 2018, 02:21:38 pmSchottky-TTL logic (74AS, 74ALS, etc), emitter coupled logic (ECL, PECL, LVPECL, etc), some programmable logic (CPLD, FPGA) and application specific ICs may have propagation delay under 10ns...

author: Benta
author_rank: Super Contributor
timestamp: December 21, 2018, 04:03:14 pm
content: 74ACxx powered at 5 V will run to 125 MHz (flip-flop clock speed).

author: joeqsmith
author_rank: Super Contributor
timestamp: December 21, 2018, 09:49:16 pm
content: I picked up one of those cheap Arty boards a while back and was able to clock it at 700MHz.https://www.eevblog.com/forum/microcontrollers/typical-speed-of-fpgas/msg1282290/#msg1282290

author: RoGeorge
author_rank: Super Contributor
timestamp: December 21, 2018, 09:59:02 pm
content: Unless it's a very simple logic, logic IC's like the 7400 series are rarely used nowadays.Instead of discreet 7400 type logic, nowadays FPGAs/CPLDs are used. and most of them (FPGAs/CPLDs) can do 100MHz or more. Even more, there is a myriad of microcontrollers that can do logic operations in the 100s of MHz range.What logic do you want to implement? How complex it is? What project do you had in mind while you were asking the question?
Logic Level conversion - Page 1
Forum section: electronics / beginners

author: drinkinglizard
author_rank: Newbie
timestamp: July 19, 2025, 03:32:09 am
content: There seems to be a few basic ways of doing logic-level conversion (MOSFETs, dedciated level shifters, voltage dividers, diodes).I've done a fair bit of searching on the pros/cons of each but am now confused by the sheer volume of it all.What am I wanting to do? Let's say for example that I have an FPGA (a Lattice ICE40) and I want to interface it with some 3V3 or 5V I/O, which technique is going to give me the lowest signal propagation latency?If I were to use something like a 74LVC245 it seems that the latency is comparatively high (in the order of 5-10ns), are there any techniques that would give sub 1ns delays?Note that the 74LVC245 approach is likely good enough for my use case, but at this point I'm just curious to know what technique is the fastest.

author: Smokey
author_rank: Super Contributor
timestamp: July 19, 2025, 03:41:30 am
content: https://www.ti.com/product/SN74AUC245Drop in with 1.7ns prop delay.

author: jwet
author_rank: Frequent Contributor
timestamp: July 19, 2025, 02:57:17 pm
content: There are a class of unbuffered FET type automatic bidirectional level shifters. They're akin to Quick Switches or Bus Switches but can shift levels. Maxim and TI make them I know. Its basically an enhanced channel of a FET, there is no switching as in standard CMOS- no buffering. The prop delay is just the delay in driving their capacitance with a finite driver. They look like a 10 ohm resistor with 15 pF or so of capacitance. (RC= 150 pS open circuit)The TI LSF002 should give you an idea. Without too much loading, prop delay is is about .35 nS.
Logic level converter - Page 1
Forum section: electronics / beginners

author: @rt
author_rank: Super Contributor
timestamp: March 23, 2017, 07:48:11 am
content: Hi GuysThis is what Jaycar in Australia market as a 2 channel bidirectional logic level converterNot exactly what I had in mind when it’s called “bi directional" if I’m looking at it right.Am I misinterpreting something with this? A single bi directional level converter would have a power supply, and just 2 pins per channel.This looks like you could convert a voltage in one direction, but is four channels to me.Unfortunately I’ve ordered eight more of these to use for a 16 bit bus which is really bidirectional.Think for example if a 3.3V controller is programming a 5V EPROM, and the data would go the other way when reading opposed to when writing.Does anyone recognise what circuit this would be? The devices on the one I have are less readable than the image.Cheers.

author: quitenothing
author_rank: Newbie
timestamp: March 23, 2017, 08:23:29 am
content: Hello,This board looks like the old logic converter from Sparkfunhttps://www.sparkfun.com/products/retired/11978.Hope that help.

author: Nusa
author_rank: Super Contributor
timestamp: March 23, 2017, 09:04:49 am
content: The sparkfun link looks right for your picture, and they include the schematic. The circuit assumes you have the higher voltage on the HV side and the lower voltage on the LV side. The two channels using the mosfet really are bidirectional. The two channels using voltage dividers not so much. Sparkfuns current product uses mosfets on all four channels. You can find other vendors that put more channels on the board.You can also find IC's that do level-shifting, with 4 or 8 bits in the same package. Search for "bidirectional voltage level translator" on your favorite chip supplier.

author: @rt
author_rank: Super Contributor
timestamp: March 23, 2017, 09:39:15 am
content: HiThanks for the replies. Yes it does look like one side is bidirectional, and the other, just a resistor divider.At least it’s fine for what I wanted.The supplier’s idea of a data sheet is this:https://www.jaycar.com.au/medias/sys_master/images/8936222490654/XC4486-dataSheetMain.pdf
Logic probe issue - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 13, 2017, 02:03:02 pm
content: HiI've got an old Micronta digital logic probe. It is running from 9v from my DP832 and is configured as NORMAL (not PULSE) and TTL/LS (not CMOS). The ground lead is connected to ground.I have a new Z84C0010PEG SBC project and so far it looks like the very simple test code is running ok.I've connected a genuine SN74LS374N Octal D Type Flip Flop and all the code does is write a pattern once to the D inputs of the device and then HALT. The data is strobed through with a 74LS138.If I probe with the scope, the individual Q output levels are HIGH (MAX 3.72v) and LOW (MAX 200mV) flat lines as expected.However, if I use the logic probe, a couple of the HIGH outputs sound very flaky. A couple sound as if they aren't steady HIGHs and the other produces atickingsound. When I changed the code to drive thetickingoutput to LOW, the LOW looks good on the logic probe.I've swapped the device but that made no difference.The Q outputs are not connected to anything at the moment.I've checked for shorts on the data lines.What's going off ?Thanks

author: stj
author_rank: Super Contributor
timestamp: July 13, 2017, 04:06:54 pm
content: a logic probe is supposed to be powered from the target to get the reference for high & low.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 13, 2017, 04:51:44 pm
content: Thanks for the reply.Valuable advice.However, it looks like I have found the issueI was running the logic probe on 9v, which I thought was the correct voltage. I dropped it down to 6v and all has been good since.

author: stj
author_rank: Super Contributor
timestamp: July 13, 2017, 07:23:41 pm
content: correct voltage is the voltage the chip is running from - in this case probably 5v.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 13, 2017, 07:34:24 pm
content: Yes thanks. I just moved the clips over to the same 5v and it all looks good.

author: Ian.M
author_rank: Super Contributor
timestamp: July 13, 2017, 07:51:54 pm
content: That's one weird probe!http://burningsmell.org/media/micronta-logic-probe-22-303.pdfQuote from: ManualWTF: "Thresholds will deviate if the same power supply for Logic Probe and the systems to be tested is used simultaneously."Tandy put the protection diode in the negative lead!The *ONLY* indication that you need to power the probe from 5V in TTL mode is in the specifications:Quote from: Manual"TTL/LS (5V Vcc)" - not exactly obvious

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 13, 2017, 08:49:53 pm
content: Yes, that's the one. I bought it nearly thirty years ago.The troubleshooting section at the back of the manual didn't include my issueAre the eBay cheapies any better ?

author: Ian.M
author_rank: Super Contributor
timestamp: July 13, 2017, 09:14:34 pm
content: Maybe, maybe not.Why not take a 1K pot, put it across the supply and probe the wiper then twiddle it to find the actual thresholds of your probe and measure them?There are reports of the Microntia probe missing narrow low duty cycle pulses . . .
logic probe vs pulser probe? - Page 1
Forum section: electronics / beginners

author: jaunty
author_rank: Regular Contributor
timestamp: September 22, 2018, 06:24:27 am
content: I've managed to avoid dealing in any depth with logic ICs for the last forty odd years since i got into this as a hobby ... so I just bought a probe to check some antequated 7200 series logic chips. HOWEVER it looks like i'll need a pulser too to inject signals around the board etc ... the ones i've looked at were combination pulser/probes all in one unit .. HOW ON EARTH are you supposed to use one of those??? i thought the point was to inject it somewhere upstream of the area you're looking at and then work down ... () wouldn't a separate dedicated pulser work a lot better - or at allthanks

author: wilfred
author_rank: Super Contributor
timestamp: September 22, 2018, 06:54:31 am
content: Sometimes (often?) logic probes have a pulse/memory feature that can be used to show a rapid pulsing signal you are probing as a slow pulsing LED. An example would be a multi MHz clock line for a microprocessor. But if you are looking for a single pulse or level transition then you set it to Memory so that the LED stays lit so you won't miss it.Just a quick look on Ebay shows the not surprising confusion due no doubt to language.You are expected to have a pulser AND a probe as you realise.

author: jaunty
author_rank: Regular Contributor
timestamp: September 22, 2018, 08:05:49 am
content: hmmm - not sure i'ts a language problem really ... talking about something like THIS ... i don't see how you can have both in one probe since the pulse is generated at the same point it's being picked up (?)https://www.amazon.com/ECG-PR-31-Generator-Signal-Frequency/dp/B008UEKXQO/ref=sr_1_2?s=industrial&ie=UTF8&qid=1537603482&sr=1-2&keywords=logic+probe+pulse&dpID=21gMRWvknWL&preST=_QL70_&dpSrc=srch
Logic Pull Up resistors  - Page 1
Forum section: electronics / beginners

author: Jbliss
author_rank: Regular Contributor
timestamp: December 23, 2015, 12:12:43 pm
content: HiI have just started learning simple logic using 4011's and 74hc02 (parts i had available). and I have a question is it nessiscary to use pull up resistors on the input always. so far I have had no such luck with out them.Could i be doing something wrong.Some circuits Show with out themThanks Josh

author: SeanB
author_rank: Super Contributor
timestamp: December 23, 2015, 12:28:38 pm
content: If using with a switch yes, if using from the output of another IC no. Pull up for CMOS is very forgiving, you can use from 220R to 1M at low speed, though you probably will want to stick to around 2-10k for most cases. Connect unused inputs to a power rail via a 10-100k resistor, otherwise they will float and may oscillate.

author: Jbliss
author_rank: Regular Contributor
timestamp: December 23, 2015, 12:33:04 pm
content: Thank You.

author: Jbliss
author_rank: Regular Contributor
timestamp: December 23, 2015, 12:59:39 pm
content: Just another question whats the largest number for a 4 bit adder

author: matseng
author_rank: Frequent Contributor
timestamp: December 23, 2015, 01:50:45 pm
content: Quote from: Jbliss on December 23, 2015, 12:59:39 pmMmmm? 15Unless you use more than one 4-bit adder in conjunction - then it might be 255, 4095, 65535, 1 048 575, 16 777 215, 268 435 455 or 4 294 967 295 for 2,3,4,5,6,7 or 8 of the adders ganged up.This is for unsigned numbers. If you want to process both negative and positive numbers you have to divide those values by two.

author: Jbliss
author_rank: Regular Contributor
timestamp: December 23, 2015, 01:52:47 pm
content: https://izatxamir.files.wordpress.com/2010/02/4-bit-full-adder.jpegfor a circuit like this highest number ?

author: matseng
author_rank: Frequent Contributor
timestamp: December 23, 2015, 01:55:33 pm
content: It can add two 4-bit numbers each ranging from 0 to 15. And return a number between 0 and 31 since the CarryOut can be considered a 5th output bit.

author: Jbliss
author_rank: Regular Contributor
timestamp: December 23, 2015, 02:43:51 pm
content: Thank Youmerry christms
logicport and additional current? - Page 1
Forum section: electronics / beginners

author: pb
author_rank: Contributor
timestamp: November 17, 2010, 07:46:58 am
content: I was trying to debug an issue tonight using an Intronix Logicport USB logic analyzer. I had most of the channel probes connected and all of the ground lines. By chance I disconnected the IDC connector on the logicport (instead of disconnecting each channel probe) and noticed the current reading on the bench supply dropped from .5A to ~.28A.Playing around a bit more, I started disconnecting groups of channels to see if one channel in particular was causing the additional load. Eventually, disconnecting a specific one of the ground probes dropped the current back to .28A. Other ground probes were connected and I didn't replace all of the disconnected channel probes to see if it was really just that ground connection but I'm curious if this additional load is normal? I guess I expected a small additional load as a result of the probes but 2X seems pretty high.The circuit in question is an 8088, 8284, RAM, 27C020, associated address logic, etc... if that matters.Update: after thinking about this more, I guess this isn'tadditionalload but reducing the load given the current goes up. no?thanks,

author: allanw
author_rank: Frequent Contributor
timestamp: November 18, 2010, 12:35:36 pm
content: Doesn't make sense. Logic inputs are supposed to be high impedance.If it was changing from a ground probe being inserted then it was some kind of grounding issue. You should do some more experimentation with the ground connection. Perhaps connecting the ground probe which is connected your computer ground which goes to mains ground can affect your power supply or your circuit somehow?

author: pb
author_rank: Contributor
timestamp: November 23, 2010, 03:34:27 am
content: Quote from: allanw on November 18, 2010, 12:35:36 pmThe additional current occurs when I connect a second ground probe (2 of 4). Doesn't matter which two and happens even when no non-ground probes are connected (i.e. only two ground probes). So.. off to investigate more.
Logisim - Page 1
Forum section: electronics / beginners

author: rudolf97
author_rank: Newbie
timestamp: August 09, 2014, 06:02:25 pm
content: Hi!I am a noob in electronics and I want to get into it. I found some nice german tutorials (of course my language) about making a 4-Bit cpu with Logisim. So now I want to know if its a good idea to learn in Logisim and if it is good to engineer things in there?The software can be found here:http://www.cburch.com/logisim/RegardsRudolf

author: zerorisers
author_rank: Regular Contributor
timestamp: August 09, 2014, 06:15:19 pm
content: Hi!From the link the first pages image looks like it can be very helpful. I might actually install it myself. I believe it would be worth learning logisim personally. Nice way to simulate these logistic circuits.Best of luck,zerorisers

author: bwat
author_rank: Frequent Contributor
timestamp: August 09, 2014, 06:23:37 pm
content: Tutorials are OK if it's a niche area which doesn't have any good textbooks covering it and the tutor is an expert. However, there are a handful of good digital design books which will teach you how to design and build your own CPU. I would get my hands on a good book and work through it.As for multisim, well if it works then why not learn it and use it for simulation. If, on the other hand you want to realise your CPU in FPGA or silicon, then you might want to learn something like Verilog or VHDL (*). If you want to see CPU designs in Verilog then have a look at some of the linkshere. All of the code was written whilst going through the bookMano, M. Morris, and Kime, Charles R.Logic and Computer Design Fundamentals. 2nd Edition.Prentice Hall, 2000.*) Note that you can still simulate designs written with Verilog or VHDL.

author: NRoach44
author_rank: Contributor
timestamp: August 10, 2014, 04:56:03 pm
content: The Digital design unit I did last semester in Uni was building parts of a processor in logisim. We followed the book "Digital design and Architecture" (David and Sarah Harris). While we didn't actually build a CPU in it, it required understanding the 8-bit MIPS CPU the lecturer built in it.I'd say as long as you are following a book or working towards some goal it should be fairly good as a learning experience.
Logitech Z623 HD15 Pinout? - Page 1
Forum section: electronics / beginners

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: November 06, 2022, 07:28:27 am
content: I've been poking this thing with a multimeter for half an hour now...Basically, I have two of the subwoofers, but want to run one without the satellite speakers. (or with other (ceiling) speakers running off the internal amp)It uses a HD15 connector with an umbilical cord to the right speaker, then then houses the volume and bass controls, as well as a headphone out, and third! line level input connector.Logitech have adopted this connector for most of their speakers, while changing the pinout nearly every single time...Suggestions?Thanks!
Logo of IC  - Page 1
Forum section: electronics / beginners

author: darrui
author_rank: Newbie
timestamp: September 07, 2025, 02:22:40 pm
content: If notice, there is a logo like a R word that has been mirrored by y-axis and has merged to a J word on the attached image IC .I want to know to which company belongs this logo .Sincerely yours all

author: Grandchuck
author_rank: Super Contributor
timestamp: September 07, 2025, 02:37:24 pm
content: Underwriters Laboratories

author: TimFox
author_rank: Super Contributor
timestamp: September 07, 2025, 03:09:40 pm
content: Yes, that monogram means “recognized by Underwriters Laboratory”.

author: gamalot
author_rank: Super Contributor
timestamp: September 07, 2025, 03:30:12 pm
content: UL Recognized Component.

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: September 07, 2025, 03:35:42 pm
content: A little unusual marking for an IC, unless it is some sort of isolation IC, which for safety reasons, Underwriter’s would like to have some leakage current specs.And no manufacturer logo….To provide context, what is this board

author: gamalot
author_rank: Super Contributor
timestamp: September 07, 2025, 03:38:08 pm
content: Quote from: UnijunctionTransistor on September 07, 2025, 03:35:42 pmIt should be a HCPL-2200
Long Banana Leads or Extensions? - Page 1
Forum section: electronics / beginners

author: Xplode
author_rank: Contributor
timestamp: February 16, 2016, 04:47:48 am
content: I am still messing around with setting up my desk/bench and I have a PSU off to my left, but I often have things all over my desk and sometimes they're further away than 36" especially if I want to route the cable around the back of the desk so its not across my lap.long story short, I've been looking around online for a decent quality set of Banana to Alligator leads (or just banana extensions!) that are longer. something in the 5' range would be awesome. Or even some 36" extensions, but I'd really like to get the kind with the red and black wires joined together so I don't have more loose cables on the desk... Also, decent guage wire so if I'm pulling 5A down for something, I don't have to worry about extra loss at low voltages.I suppose a less lazy way would be to mount a little distribution panel with some banana jacks on that side of the desk and wire it up to the supply, but I'd like the leads for now instead.Thoughts, suggestions??Thanks guys!

author: sleemanj
author_rank: Super Contributor
timestamp: February 16, 2016, 06:17:02 am
content: Make your own, you get the length you want, the quality of cable you want, and the type of fittings you want.Silicone type wire with high (tinned copper) strand count make for nice flexible test leads.

author: mojoe
author_rank: Frequent Contributor
timestamp: February 16, 2016, 04:25:32 pm
content: I just bought some banana-to-banana leads from Cal Test (mentioned in another thread on this forum). High quality and a bit pricey. I didn't want 10 of a single color, so I had to order from Test Path, one of their distributors. Amazon.com also carries several Cal Test items. The stacking banana with retractable safety sleeve is very nice.

author: mstoer
author_rank: Contributor
timestamp: February 16, 2016, 05:28:14 pm
content: I bought some Elenco brand banana-minigrabber leads off Amazon last year and they are OK. The leads themselves are not as flexible as I'd like, but the grabbers are OK and the banana plugs stack. I make banana extensions/patchcords with silicone rubber stranded wire (192/41) made for test leads by Pomona (bought from Digikey). I wish the Elenco leads had used that wire.So I vote buy some basic stuff and make the rest.

author: apelly
author_rank: Unknown
timestamp: February 16, 2016, 06:27:08 pm
content: Quote from: sleemanj on February 16, 2016, 06:17:02 amThis.Franky (iloveelectronics) has good cable for an honest price.
long distance wireless spy devices  - Page 1
Forum section: electronics / beginners

author: Ian
author_rank: Contributor
timestamp: July 06, 2011, 12:55:50 am
content: Hiso i have bean wanting to make some long distance wireless spy microphone. i found some tutes but they can only go through a couple rooms. it does not need to go a couple miles. just a 1/4m or so if that far. so if you could help me that would help a lot.

author: johnboxall
author_rank: Unknown
timestamp: July 09, 2011, 05:40:43 am
content: Visit here -http://www.talkingelectronics.com/te_interactive_index.htmlOn the left is a long index of pages, scroll down to FM bugs (etc.)Colin has got you covered - there are heaps of different transmitter circuits.
Long life coin cells? - Page 1
Forum section: electronics / beginners

author: larangel3
author_rank: Contributor
timestamp: January 05, 2016, 08:30:43 pm
content: Where can I purchase coin cell batteries with a lifespan of at least 2 years?They will be used to power a very small circuit with power requirements ranging around .2 mA

author: mikerj
author_rank: Super Contributor
timestamp: January 05, 2016, 09:10:15 pm
content: Quote from: larangel3 on January 05, 2016, 08:30:43 pmMore detail is needed, what is the duty cycle of the circuit, i.e. the on times vs off time? If you drew 0.2mA continuously for two years you'd need a 3.5Ah cell which is not going to be anything like coin sized.Just for reference one of the largest commonly available coin cells is the '2032' which has around 240mAh capacity, enough to power your circuit continuously for about 1 1/2 months. Any quality brand lithium coin cell would be fine for standby duty for two years (i.e. their self discharge is very low, about 1% per year).