hybridfree/eevblog-posts huggingface dataset:
Logic family for driving signals on a VME bus - Page 1
Forum section: electronics / projects

author: TomS_
author_rank: Frequent Contributor
timestamp: April 11, 2023, 10:19:07 am
content: Hi all,Im working on a project where Im re-using a VME bus backplane because Ive already got it so why not (and its a 68k based project so its quite fitting).Im stuck in a little situation where there are just a couple of signals remaining that I need to drive across the backplane, either as push/pull or open collector/drain, and Im looking for a suitable logic family that coule accomplish the task.For the vast majority of signals (data bus, address bus, and a bunch of control signals) I am using 74FCT series logic, which from what I read seems like it might have been intended for this particular application.There are a couple of signals left that I need to drive:SYSCLK as push/pull (output to bus only)SYSRESET/ as open collector/drain (output to bus only)BERR/ as open collector/drain (bidir to/from bus)DTACK/ as open collector/drain (bidir to/from bus)VME busses tend to have pretty hard termination resistors, 330ohm over 470ohm on either end of the backplane, which to me sounds like 165ohm over 235ohm, and needing the ability to drive 20-30mA of current. I *think* that LVC series logic might be capable of this, and I was considering using a handful of 74LVC1G125's to complete the task, but I thought I might ask in case I just have this completes ass backwards.My thought is:For SYSCLK I would configure the gate as a buffer driving the bus directly (OE/ tied low, signal in is signal out)For SYSRESET/ I would configure the gate to act like an open drain device driving the bus directly (tie the input low and use OE/ to toggle between hi and lo Z)For BERR/ and DTACK/, much the same as SYSRESET/ but in parallel with the bus rather than driving directlyDoes anyone have any insight they could share?Thanks!

author: Benta
author_rank: Super Contributor
timestamp: April 11, 2023, 12:03:06 pm
content: For the OC parts, look at 74LVC1G06/1G07.

author: TomS_
author_rank: Frequent Contributor
timestamp: April 11, 2023, 03:08:04 pm
content: Was hoping to minimise part count, since Im already using some 74LVC1G125s elsewhere in the circuit.

author: Benta
author_rank: Super Contributor
timestamp: April 11, 2023, 03:21:48 pm
content: 3-state is not the same as OC/OD. You may get it to work at runtime, but I'd be worried about startup/shutdown.
Logic gate pinout - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: December 28, 2019, 09:54:51 am
content: Does there exist a 74LSxx NOR gate, in 14-pin DIP package, which has the same pinout as the 74xx00 ?i.e 1=A, 2=B, 3=Y pinout.For a teaching project I want to have a set of ICs for every Boolean gate type, e.g. 74LS00, 74LS08, 74LS32, 74LS86.Assume all the gates are quad-package 2-input, DIP 14-pin.I want them to all have the same pinout, so students can just keep the wiring identical and swap the logic function.But I can't get a NOR which is right.The 74xx02 NOR devices have a "backwards" pinout, where pin 1 is Y, pins 2 and 3 are the inputs and so forth.

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: December 28, 2019, 11:28:23 am
content: I don't believe so, but4001 quad 2-input NOR4011 quad 2-input NAND4070 quad 2-input XOR4071 quad 2-input OR4077 quad 2-input XNOR4081 quad 2-input AND4093 quad 2-input NAND with Schmitt trigger inputsAll share the same pin assignments.

author: duak
author_rank: Super Contributor
timestamp: December 28, 2019, 09:37:49 pm
content: The 74x33 quad NOR with open collector outputs has the same pinout as the 74x02, unfortunately. At one there could have been a market for such a device albeit at a higher price.This probably won't help but if the 74x02 is rotated by 180 degrees AND Vcc and ground are swapped, the inputs and outputs are the same as the 74x00 quad gates. I fixed a colleagues design with this little trick that allowed him to proceed with testing.All the best,

author: David Hess
author_rank: Super Contributor
timestamp: December 29, 2019, 11:41:47 am
content: I do not remember why the 74 series NOR gates have a different pinout.TI made the 74ALS1032A which is a quad 2-input NOR gate with the same pinout as the 74LS00, 74LS08, 74LS32, and 74LS86.
Logic IC power-off low side switch & decoupling - Page 1
Forum section: electronics / projects

author: smoothVTer
author_rank: Regular Contributor
timestamp: October 11, 2019, 03:32:48 pm
content: I've designed a clock subsystem that runs off a clipped sine wave oscillator. The oscillator itself has no enable pin; enable/disable is done by turning on/off the supply to the oscillator via an LDO. When the LDO is off, the oscillator is off, and the output of the oscillator is Hi-Z. This leads to the inverter oscillating about its resonant frequency due to Rf/Cf, a situation which burns power when the clock subsystem is supposed to be off.Thus I need to switch power to the inverter on or off. The easiest way to do this is for me to switch ground, as I can use a low side NFET to switch ground to the inverter using the same logic as the EN to the LDO.Question is: where dooes the decoupling cap go between when using a low side NFET is this fashion? Point #1 ( the GND pin of the inverter ) or #2 ( true ground point )? Does it matter? If it matters, why does it matter?For reference schematic:

author: ledtester
author_rank: Super Contributor
timestamp: October 11, 2019, 10:42:23 pm
content: Shooting from the hip here with an alternative idea... would a weak pull-down on the inverter input do the job?Another idea - use a NAND gate instead with the other input fed from EN. Or somehow pull the inverter input to GND when EN is low.

author: Ian.M
author_rank: Super Contributor
timestamp: October 12, 2019, 02:17:54 am
content: If the inverter supply current is low enough, you can simply power it from the same I/O pin that drives the LDO EN signal. Reduce its decoupling to 1nF so you don't overload the pin for too long when switching it.,

author: smoothVTer
author_rank: Regular Contributor
timestamp: October 24, 2019, 04:07:28 pm
content: Thanks, this solution works great!
Logic level from comparator to raspi gpio - Page 1
Forum section: electronics / projects

author: PhelarNord
author_rank: Newbie
timestamp: December 25, 2019, 08:51:40 pm
content: Hi!Im doing a simple voltage monitor with a lm393. I´m going to use a raspbarry pi´s gpio´s to register the state of the comparator outputs but need some advice to translate the output from the comparator to3.3v. Can i manage this with just a voltage divider or do i have to use something more solid.Cheers

author: Ian.M
author_rank: Super Contributor
timestamp: December 25, 2019, 09:07:10 pm
content: The LM393 has an open collector output. Simply use a 10K pullup resistor from its output to Pi +3.3V, and it will be logic level compatible.N.B. LM393 Gnd must connect to Pi Gnd. You can power its Vcc pin from Pi +5V.

author: PhelarNord
author_rank: Newbie
timestamp: December 27, 2019, 07:46:03 pm
content: Thanks!I´ll do this in the design
Logic level shifting (0,3.3) to (-8,6) - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: October 20, 2016, 03:26:23 pm
content: I'm looking at trying to slim down a logic translation circuit.The sensor I'm working with uses control signals that go from -8V to 6V. I'm currently using a gate driver to do this and it works well. The issue is that I'm attempting to save some board space and these SOIC-8 packages are just way too big.I'm attempting to switch these to simple differential translator or level shifter. These can come in small SC-88 and UFQFN packages and would be fantastic for my application. The problem is that the max voltage rail values seem to limit these to LVTTL and my 14V swing would be well beyond what they can handle.Does anyone have any suggestions that I could look at, or alternatives?

author: DaJMasta
author_rank: Super Contributor
timestamp: October 20, 2016, 07:46:06 pm
content: I certainly don't know much about logic operating at those levels, but if they're operating quick enough (no long waits in one state or the other that need to be read as data) and you only need the single direction, why not do it with passives?AC couple -> Bias to make it 0 to +14 -> voltage divider -> LVTTLIf you've got a 7V (or more) supply available and your signal won't be messed up with the ac coupling low pass filter, it could be a cheap and compact option.
logic of connecting biasing system to amplifier question - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: August 06, 2025, 10:34:20 am
content: ello , I have a system which consists of an amplifier a biasing PCB and a protoboard.we connect the two pcb on the protoboard described below photo 1.I have the the biasing pcb shown on photo 2 and described on the link it has pin holes 1 2 3 4.On photo 3 we have the amplifier it has pin hole called 5.I know that I connect them to gether using spring pin.(from the getting started manuals attached)but the biasing pin has four holes and the amplfier has one hole.How do I use these holes so the biasing pcb will function with its amplifier?Thanks.biasing:https://catalog.quanticxmw.com/item/bias-and-control/voltage-regulators/xm-a2j4-0404d-spamplifier:https://catalog.quanticxmw.com/item/x-mwblocks/amplifiers/XM-A9V6-0604D

author: mtwieg
author_rank: Frequent Contributor
timestamp: August 06, 2025, 11:24:30 am
content: From the documentation, it seems like there are different versions of bias control board, I assume you have to pair the correct bias control board with an amplifier board.The documentation also says:QuoteFrom the pictures of that specific bias board, it looks like two of its holes are for GND, while two are for outputs. In photo 1, it looks like only one of the these is actually connected with a spring pin.But it's anybody's guess as to whether that's correct for your specific amplifier board. Their documentation should provide that information.

author: eutectique
author_rank: Frequent Contributor
timestamp: August 06, 2025, 11:29:46 am
content: What was the response from the manufacturer?

author: john23
author_rank: Frequent Contributor
timestamp: August 06, 2025, 12:19:19 pm
content: hello mtwieg,In the link they say officially that recoomended system is XM-A2J4-0404D-SPWhat is the strategy for connecting those two?where can I find a specific manual?https://catalog.quanticxmw.com/item/x-mwblocks/amplifiers/XM-A9V6-0604DThanks.

author: mtwieg
author_rank: Frequent Contributor
timestamp: August 06, 2025, 09:03:35 pm
content: Quote from: john23 on August 06, 2025, 12:19:19 pmOk, looks like this is the bias controller they recommend.Looking at the layout, it seems the two pins are actually both the same net, so you could use either one to connect to the amplifier board.Seems like the input DC supply is supposed to be connected with a wire soldered directly to the PWR_IN pad.No idea if there is any other connections required. If you need more info then you need to contact them directly.
logic of connecting two  RAC04-12DC/230 in certain way - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: May 15, 2024, 01:37:54 pm
content: Hello , I have two RAC04-12DC/230 which are connected in layout as shown below.the component pin are described in the datasheet and the attached table.The device has 3 modes of operation by which is desided what in the exact role of each pin.I dont know what mode the devices are in.Using the attached photos i saw that pins 5 of both devices are connected,also pins 6 of both devices are connected,as shown in the attached layouts.Also there are +12V -12V line come out i dont know where from.What could be the logic of connecting these devices in such way?Thanks.

author: eutectique
author_rank: Frequent Contributor
timestamp: May 15, 2024, 08:05:50 pm
content: Quote from: john23 on May 15, 2024, 01:37:54 pmIn which way? Connecting pins 5 and 6? To supply both devices with VAC in (N) and VAC in (L).Did you read the datasheet?

author: john23
author_rank: Frequent Contributor
timestamp: July 04, 2024, 08:47:43 am
content: Hello, Sorry for the late responce.I need to use two type of the componens.From the attached table I need to use RAC04-12DC/230 to get +-12 and RAC04-24SC/230 to get +24 signe ended.RAC04-12DC/230 is dual mode from the photo below.What is the meaning of COM at pin 3 shown in the photo below?What is the difference between DUAL is single mode with pin output?https://www.mouser.co.il/datasheet/2/468/RAC04-C_230-1711174.pdf

author: eutectique
author_rank: Frequent Contributor
timestamp: July 04, 2024, 11:21:35 am
content: Quote from: john23 on July 04, 2024, 08:47:43 amClickhere.

author: john23
author_rank: Frequent Contributor
timestamp: July 05, 2024, 08:18:01 am
content: Hello , so if I want 24v single mode I will use RAC04-24SC/230 and put 24V vout plus , vout minus pin3=GND?correct?Dual mode:And if I want +-12V I will use RAC04-12DC/230 Pin2 +12 pin4 -Vout Com=GND?correct?
logic of fixing biasing misselighnment - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: April 05, 2025, 02:26:07 pm
content: Hello ,In the video at 6:49 they say that the biasing is not alighed and we need to fix it.Looking in the diagram of the attached photo,where is the misalighnment we need to fix using feedback?Thanks.

author: john23
author_rank: Frequent Contributor
timestamp: April 12, 2025, 03:51:55 pm
content: Hello,I have built a circuit presented below.How can I create a common mode missalighnment which I could fix later using feedback?Ltspice file is attached.Thanks.

author: john23
author_rank: Frequent Contributor
timestamp: April 12, 2025, 05:40:01 pm
content: update2:I have created a misselighment by changing mosfet W and I connected the V3 as independant source.How feedback will fix this misselighnment?
logic of opening pmos and nmos simultaniosly - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: October 15, 2024, 08:46:22 pm
content: Hello, node "e" is rising after the pulses stabilize.There are PMOS and NMOS which need to be open simultaniosly.What is the logic in using NPN with a diode to open these mosfets?Also why M1 has 100uF capacitor at the gate while M2 has only resistors?Thanks.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: October 16, 2024, 12:33:17 am
content: Quote from: john23 on October 15, 2024, 08:46:22 pmThat looks to be a kludge attempt to match the FET threshold with the 1.2V transistor + diode threshold.Once that is reached, the top PMOS turn on rapidly.It is approximate only, and roughly matches one point of the curve, without much consideration of speed or slopes, or part variations.That may be 'good enough' in this application.

author: Andy Chee
author_rank: Super Contributor
timestamp: October 16, 2024, 04:01:40 am
content: Is this a continuation of your same project?https://www.eevblog.com/forum/projects/analog-logic-of-comprator-based-analog-stabilier-pulse-circuit/msg5674515/#msg5674515https://www.eevblog.com/forum/projects/converting-power-supply-signal-into-pulse-signal/msg5670163/#msg5670163https://www.eevblog.com/forum/projects/fixing-design-for-simultanios-excitation-of-a-sequencer/msg5643509/#msg5643509https://www.eevblog.com/forum/projects/bjt-invertive-switching-logic-question/msg5624647/#msg5624647https://www.eevblog.com/forum/projects/pure-dc-voltage-delay-mechanism-question/msg5621559/#msg5621559

author: john23
author_rank: Frequent Contributor
timestamp: October 16, 2024, 09:22:25 am
content: Hello PCB.Wiz,Yes We need to match the absolute vslue of Vgs on bot mosfets at a certain time point, so they open at a certaint ime point.We have node e starting to rise.Its going to NPN ,whic has a resitor form one side the a diode on the other side.NPN is just a valve to create certain Ic current.Also the diode is touchin the drain.What is the point in this?Thanks.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: October 16, 2024, 07:04:49 pm
content: Quote from: john23 on October 16, 2024, 09:22:25 amThat now acts as a AND gate, so the drain must be lowandthe cap > 1.2V before the upper FET starts.ie it sequences the rails so the negative rail always comes up first.The exact delays depend on the lower mosfet threshold.Spice will easily show you all of this. Change a few things and see for yourself.
logic of rectifier shape on the output of the opamp - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: July 12, 2025, 09:19:42 am
content: Hello, could you please explain the shape of Vy in the circuit below.what is the logic behind the shape?Ltspice file is attached.Thanks.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: July 12, 2025, 09:55:55 am
content: Quote from: john23 on July 12, 2025, 09:19:42 amWhat did you expect?The OpAmp tries to make the IP pins ==.It can do that ok for the diode-forward case, with Vo one diode above Vin, but it cannot succeed on the reverse swing.

author: Zero999
author_rank: Super Contributor
timestamp: July 12, 2025, 10:07:49 am
content: Yes, the op-amp tries to keep both of its inputs at the same voltage.When the op-amp is positive, its output is a diode drop above the input voltage and the voltages at both inputs are nearly identical.when the input goes negative, the op-amp tries to make both inputs equal, but it can't, so the output voltage swings all the way to the negative rail.
Logic only PIR modules/assemblies? - Page 1
Forum section: electronics / projects

author: John B
author_rank: Frequent Contributor
timestamp: July 16, 2020, 06:14:54 am
content: I've been experimenting with lighting motion sensors sending logic only signals back to a micro to control lights. I'm working up to a more polished and permanent house install, so I'm looking for typical ceiling recessed or surface mounted plastic units that you might buy from the hardware store.They come in two usual varieties - mains powered and mains switching ones, and 12v units that switch a relay. While the form factor is fine, they both switch a power source using a relay. Neither of them are particularly cheap or low power, and ultimately I only need the logic signal.I've been using some PIR modules that look like they could be the PCB from inside one of these plastic units. The benefit is that they are cheap and very low powered (quiescent power is 80µA @ 5V), but they are only the PCB and don't have the plastic assembly.Has anyone seen where a suitable product can be found? Or maybe the plastic assemblies which you can glue a module into?

author: Renate
author_rank: Super Contributor
timestamp: July 16, 2020, 11:25:33 am
content: I'd just get a plate (plastic, stainless steel), (round or square) and cut a hole in it for the "football".For in the wall/ceiling you really don't need a full enclosure.If you really want an enclosure use a regular electric box.
Logic porbe pulse detection - Page 1
Forum section: electronics / projects

author: ataradov
author_rank: Super Contributor
timestamp: August 03, 2015, 01:39:28 am
content: Just as a quick mental exercise I decided to create a logic probe with the following limitations:1. Show "1", "0", undefined (exact thresholds are not important).2. Show pulse signal (LED lit for ~500 ms on any level transition).3. Use a single LM339 for everything. Any passives are allowed.Schematic I came up with is attached. Exact component values are approximate and are subject for fine-tuning.Additional limitation - indicator for "1" and "0" is a dual red-green LED and a mix of red and green is used to indicate an undefined state.The problem here (apart from head-on approach) is that pulse LED remains lit for undefined state (since both LEDs need to be lit). Technically pulse detection here indicates transition of the "sum" signal to a positive value (== any of the LEDs turning off == one of the defined levels became active).The logic level detection is OK, but is there a better way to indicate pulse without using additional ICs?I have a version of the circuit that only tracks the positive edge of the "sum" signal. It is based on the small capacitor separating two parts with minor modifications to level shifting resistors. But it misses short transitions, and quite fiddly even in the simulator.
Logic Puzzle time or How I learned to love Logic and solve everything with it? - Page 1
Forum section: electronics / projects

author: mkiijam
author_rank: Regular Contributor
timestamp: November 19, 2023, 07:01:07 am
content: I need to stop relay A from changing state when relay B is on. Can it be done with logic gates and their slightly expanded universe? Just no MCU's or the like. Latching relays would be okay and I think I need momentary switches.But for the exercise I was trying to stay just with logic chips for the... ehhh.... logic, as opposed to mechanical interlocks etc. Driving the relays could of course be transistors or something, but that's not a concern at this point.Can it be done? I've ben pulling my hair out for hours! What am I missing?

author: IanB
author_rank: Super Contributor
timestamp: November 19, 2023, 07:13:25 am
content: Break the problem down into logical pieces.First of all, relay A needs to be driven by a latching circuit (a set-reset latch), which will then receive a signal to turn it on, and a signal to turn it off (or a single signal to make it change state--your choice). You need this so that relay A can stay on or off by itself, without needing any continuous external signal.Secondly, when relay B is on, it needs to interrupt the signals going to the latch for relay A, so it cannot receive any commands.

author: mkiijam
author_rank: Regular Contributor
timestamp: November 19, 2023, 07:25:43 am
content: Quote from: IanB on November 19, 2023, 07:13:25 amYes, this is so very true. But this is a mechanical interlock solution, no?

author: Andy Chee
author_rank: Super Contributor
timestamp: November 19, 2023, 08:02:18 am
content: Quote from: mkiijam on November 19, 2023, 07:25:43 amYou’re already using mechanical relays for relay A & B, so I’m not sure why a mechanical solution is being ruled out.Perhaps relay A & B are exisiting in a piece of equipment already and cannot be altered?

author: mkiijam
author_rank: Regular Contributor
timestamp: November 19, 2023, 08:14:48 am
content: An SR latch with a latching relay is getting me in the right direction... not there yet but much closer!

author: IanB
author_rank: Super Contributor
timestamp: November 19, 2023, 09:35:03 am
content: Quote from: mkiijam on November 19, 2023, 07:25:43 amIt doesn't have to be. Logic gates can also implement a switching function. For example, an AND gate.
Logic Spice Models For Altium Designer 16 - Page 1
Forum section: electronics / projects

author: w3amd
author_rank: Regular Contributor
timestamp: March 18, 2016, 10:31:01 pm
content: Hi all,I've been looking for where I can get the TI spice models or anything that can be used to model digital logic gates such as 74HCT00 and I can't seem to locate it anywhere.TIA,John

author: w3amd
author_rank: Regular Contributor
timestamp: March 19, 2016, 01:41:20 pm
content: Yeah. I did look here. Even in the total package I can't find any of the digital logic gates. I would have thought this would be easier to find.John
Logitech Headset - Page 1
Forum section: electronics / projects

author: w3amd
author_rank: Regular Contributor
timestamp: October 25, 2016, 11:50:15 pm
content: Future engineers:When you make something make it very clear WHAT YOUR PRODUCT IS DOING!DO NOT DO THIS -I own a Logitech headset. When I mute it, it gives a tone, when I mute it another.It ISN'T CLEAR what is what so now I have a reverse audio image of the coughing from my illness I try to mute out. Fantastic!

author: Audioguru
author_rank: Super Contributor
timestamp: October 26, 2016, 01:18:16 am
content: The YouTube video is "Not Available" to me.

author: grifftech
author_rank: Frequent Contributor
timestamp: October 26, 2016, 02:12:33 pm
content: Quote from: Audioguru on October 26, 2016, 01:18:16 amsame

author: w3amd
author_rank: Regular Contributor
timestamp: October 26, 2016, 07:16:18 pm
content: Sorry I pulled it down. I was so mad. It's a video of programming with telling what I am looking for and coughing. The coughing was supposed to be muted out. Instead because the headset wasn't clear the video is filled with coughing and no explanation of what I was doing. The exact inverse of what I was doing. The head set gives two tones. An up run which means on, and a down run which means off. However for people with disabilities this is simply not clear enough all the time.

author: Dave
author_rank: Super Contributor
timestamp: October 27, 2016, 10:39:03 am
content: So, basically user error and the engineers are to blame, eh? I imagine handycam designers must get a lot of heat from amateur video producers that end up recording their feet instead of their child's birthday party.

author: w3amd
author_rank: Regular Contributor
timestamp: October 27, 2016, 07:49:31 pm
content: All I can do is laugh as this response. There's never a such thing as one in engineering. If I've done it so have many others.
Logitech iphone/ipod dock 12.9 Vdc - Page 1
Forum section: electronics / projects

author: tjw
author_rank: Contributor
timestamp: January 05, 2011, 05:35:26 am
content: Hi,a workmate was telling me about his Logitech iphone/ipod dock that is powered by a 12.9v 1.39A switching adaptor (100 - 240VAC). The adaptor has failed and he is looking for a replacement.The dock has an integrated amplifier and I am speculating that it is powered by 3 X rechargable cells each with a charging voltage of > 4.0 V, hence the 12.9 V supply.Has anyone encountered this before ?Thanks, tjw.

author: saturation
author_rank: Super Contributor
timestamp: January 05, 2011, 12:34:14 pm
content: You can easily find replacement wall warts on eBay, but is your friend sure this is the cause? If you have an adjustable power supply you can cut off dead adapter's socket, rig a connector to your PSU and test it for sure.

author: Simon
author_rank: Unknown
timestamp: January 05, 2011, 12:34:49 pm
content: 3 X 1.2V = 3.6V

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 05, 2011, 01:58:37 pm
content: Does it work with just a 12v supply?
Logitech laptop tocuchpad - Page 1
Forum section: electronics / projects

author: electronics-whiz
author_rank: Regular Contributor
timestamp: February 21, 2015, 08:19:58 pm
content: I pulled a touch pad from a junk laptop a while back. I saved it with thought of adding some cable and using it as a mouse.This is the info on the pad itself: JCI-s1S H, Logitech touchpad. A sticker on it says 904251-0000There are a few SMD passive parts, and an IC. The IC says this on it: Zilog (C) 97 logitech, 331060-0050, 9750, 45(Commas separate numbers either on different line, or greatly separated.)It has an 8 pin Ribbon wire lead on the touchpad. It appears pins 7,8 are not used as just go to traces with nothing attached.Looking at the trace size by the ribbon connector it seems pins 1, 6 are power and pins 2-5 are some form of data because they connect direct to the IC on the touchpad.I can't find info for connection on the pad or the IC. Most things say the pad is PS/2 which makes since for the (C)97 on the pad. PS/2 only uses 4 pins though. 2 power, 2 data. I have 4 pins going into the IC. I don't have any click buttons for this so possible they were on the motherboard and sent back using 2 of the traces.I don't have a scope or anything to analyze the data, also not sure what the power polarity is on those 2 pins.

author: German_EE
author_rank: Super Contributor
timestamp: February 22, 2015, 09:42:03 am
content: The pad I recovered from a dead Compaq laptop some time ago used USB for the connection, although the pinout was NOT standard USB. Your only hint is that sometimes the ground connection has wider traces, after that it's pure guesswork.

author: amyk
author_rank: Super Contributor
timestamp: February 22, 2015, 03:40:46 pm
content: A quick Googling around shows this:http://pinoutsguide.com/Inputs/alps_touchpad_pinout.shtmlOne of the first documents here is a maintenance manual for a laptop that uses this model of touchpad:http://www.datasheetarchive.com/904251-datasheet.htmlIt confirms that the buttons are to be grounded to activate, and a Synaptics documentherealso shows their touchpads used the same pinout.

author: electronics-whiz
author_rank: Regular Contributor
timestamp: February 22, 2015, 10:22:14 pm
content: I used the pinouts guide link. It looks like I may be dealing with the bottom table with the 8 pins. Seems is setup like I thought and buttons sit on another PCB and link back up to the chip.I'll give it a try sometime. I may have to get hands on a PS/2 cable. I had one once, but think I used it for wire in a project.
Long linear capacitive sliders - Page 1
Forum section: electronics / projects

author: pyrohaz
author_rank: Regular Contributor
timestamp: January 05, 2016, 12:42:06 am
content: I've got a project where I'm in need of long linear capacitive sliders. My current discrete implementation is a board 600mm long with 20 capacitive buttons along with length. Obviously, this isn't particularly efficient so I'm looking to change to a linear slider implementation. My main aims are:Good linearity so I can detect position easilyNeeds to be able to detect position regardless of pressureFast sampling rate (<8ms - this was my main drive to going discrete in the first place)If possible, have multitouch capability across the slider - relatively important but not vitalThe main issues here are the fact that 600mm is pretty damn long (the whole board is 600mm x 60mm) so resolution I can imagine would suffer due to the size.Any suggestions? I'm currently using the AT42QT1070 in a separate project that has a really nice responseandallows access to the raw capacitive data for pressure measurement!Thanks,Harris
"Long-live" LCD specification - Page 1
Forum section: electronics / projects

author: Wilson__
author_rank: Frequent Contributor
timestamp: April 24, 2025, 05:32:16 pm
content: Need to choose a "most popular" colour LCD screen specification that is likely to remain in production for many years in future. For use in small batch manufacturing.Is QVGA (quarter VGA) a good candidate?Around 2 to 2.4 inches320 x 240 pixelsST7789 controller chip

author: coromonadalix
author_rank: Super Contributor
timestamp: April 24, 2025, 09:57:20 pm
content: you posted in the manufacturing section ... why another thread ?

author: thm_w
author_rank: Super Contributor
timestamp: April 24, 2025, 10:47:36 pm
content: Here is the other thread:https://www.eevblog.com/forum/manufacture/where-to-source-lcd-module/2" 320x240 is quite common.Or 1.3" and 1.5" 240x240You can do some google searches and see, and look at various supplier stocks, etc.

author: Wilson__
author_rank: Frequent Contributor
timestamp: April 25, 2025, 02:40:15 pm
content: Sorry. Thanks for advises for the forum rules.
Long range, one way ultrasonic - Page 1
Forum section: electronics / projects

author: Annakin4
author_rank: Contributor
timestamp: April 16, 2015, 08:08:13 pm
content: What would I need to transmit and than receive an ultrasonic signal roughly 120 feet or hopefully greater to be able to go into a receiver on the other side of a basketball court at a specific frequency? The plan is to have a transmitter in each corner of the court, than have recivers on robots and have them work similar to GPS to find the X and Y of each of the up to 4 bots. This is to keep human drivers from crashing into each other and cheating. We're using Atmel chipset "nodes" that send the signals and a Raspberry Compute Modual which will talk to the bots. We are aware we need really good timing, and have came up with a solution, but we just need to find something that can transmit with that much power, then what type of receiver to use.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 16, 2015, 08:34:03 pm
content: As there is no reflection included, the normal 40 kHz US transducers should have enough power. Because of the rather directional character one may need several transducers, or at least find non directional detectors. I am not sure if signal strength is enough to use a simple reflector (e.g. cone) to get an all around reception.Echos can make the detection not that simple and fast. So pulses likely need to be well separated in time, and a reasonable stable time base (e.g. quarz) is needed. An extra IR Signal may also help.

author: Marco
author_rank: Super Contributor
timestamp: April 16, 2015, 08:36:07 pm
content: A Keyringer XL works across the distance of a football field.Good signal processing is more efficient than volume.

author: LaserSteve
author_rank: Super Contributor
timestamp: April 17, 2015, 02:05:33 am
content: Use coherent detection, or lock-in amplifiers at the receivers.After all, indoors its easy to have a sample of the reference phase from the transmitter.These are basic signal processing techniques that allow you to reduce TX power while rejecting interfering sources.Steve

author: Marco
author_rank: Super Contributor
timestamp: April 17, 2015, 03:20:08 am
content: I'm not sure you even need to worry about coherent detection ... since it's for positioning you will be using a fair amount of bandwidth, say a kHz or so. Which is pretty close to the bandwidth of the piezo crystal to begin with. Any noise the detector could reject was already rejected by the piezo.So simply use AGC + an envelope detector. Amplitude modulate each beacon with a set of PNs ala CDMA at ~1 kHz, cross-correlate on the nodes to determine the distance (doing the cross-correlation with these PNs fast will require some tricky math to do it efficiently on the ATMEL, maybe FWT based schemes?).
Long shot: Toshiba TC358768 / TC358778 RGB to MIPI bridge - Page 1
Forum section: electronics / projects

author: tom66
author_rank: Super Contributor
timestamp: May 30, 2025, 08:40:56 am
content: We have this chip on a product of ours that is intended to convert RGB data from an FPGA into MIPI DSI-2 signals for a display.The issue is that the chip does not seem to function correctly. We are not using Linux, so I took the Linux kernel driver as a reference and implemented it myself for our baremetal platform. I can talk to the device over I2C and see some FIFO activity, but I do not get any MIPI signals out (verified with a 'scope, they stay at 1.2V, LP-11).There is no public datasheet detailing how registers are used - there is one dubious one online, which has been published, but I do not know how old it is or if it applies to our chip (since we have '778 and that one is '768).I am hoping someone here has had some experience with this and can nudge in the right direction.Toshiba were no help at all, insisting that they do not support this device any more.

author: tom66
author_rank: Super Contributor
timestamp: June 02, 2025, 08:59:34 pm
content: So I fixed my issues and got some kind of output from the chip, which is better than the "absolutely nothing" I was getting before.For those who want to know: the problem was caused by the device being big-endian, but this itself wasn't the issue; it actually interprets bytes within each 16-bit word in little-endian order, but words are then swapped around. So if you want to write to a 32-bit register the value 0x1234 (LE), you have to write 0x1234_0000, *not* 0x0000_1234. And you have to write the full 32-bit word to the 32-bit registers, even if that upper 16-bits is not used, or the write seems to fail. Of course, Toshiba call these 32-bit addressable registers but only specify the first 16 bits. Whomever designed this chip just really wanted to make it a headache for someone.I think this technically a "middle endian" system, because endianness (as far as I know) typically refers to individual bytes, and both the SPI and I2C interfaces use byte addressing. Though writing individual bytes isn't permitted. So, I don't know. It's a mess.I figured this out because I was finding that the values I was reading back from 32-bit registers were completely wrong, usually the last register read repeated. I tried multiple combinations until I stumbled across the correct arrangement. The Linux kernel driver mentions being in big endian mode but I had assumed that refers to byte ordering, seems that the kernel devs have encountered enough devices like this to do a kind of 16-bit big endian ordering too.
long side termination (reverse geometry) thermistors? - Page 1
Forum section: electronics / projects

author: lemonlime
author_rank: Newbie
timestamp: January 25, 2023, 04:10:48 pm
content: does anyone know some part number/product series for SMD thermistors that have their terminations on the long side of the chip, rather than the short side?I've been scrolling through digikey/mouser catalogs but I can't find the right packages. I've seen in pictures of packaged thermistor sensors thermistors that seem to fit the bill, but I haven't been able to discover what the actual chip is. (e.g.https://www.adafruit.com/product/4890)Maybe I'm just searching with the wrong terminology? I've seen packages like 0306 MLCCs that have just the form factor that I want, and manufacturers call them reverse geometry or just long side termination.https://www.tti.com/content/ttiinc/en/manufacturers/tdk/products/TDK-Reverse-Geometery-Multilayer-ceramic-capacitor-MLCC.html

author: TimNJ
author_rank: Super Contributor
timestamp: January 27, 2023, 03:55:14 am
content: Never seen one by itself. I don’t really see the advantage of offering a reverse geometry package for a standalone SMD NTC temperature sensor. Temperature is inherently slow, and I don't think a bit of extra inductance in a temperature sensing loop usually matters.The reverse geometry is probably just to make it easier to solder/weld the NTC to the leads.This might be the one, although this is quite an abridged datasheet:https://www.thinking.com.tw/upload/product/files/en-NTCThermistor-TTF Series.pdf
Long Term drift of low cost bandgap references - Page 1
Forum section: electronics / projects

author: Kay
author_rank: Contributor
timestamp: June 20, 2015, 03:02:02 am
content: Wondering what would be like the LTD of low cost band-gap voltage references?The application is to use the reference inside PIC16F1503 (1.024V) for a Li-fepo4 battery charger. Product lifetime would be 3-5 years.even if the reference drifts 1.5% in 5 years, it is still within the spec.The reference inside PIC16F1503 has a tolerance of 4% over -45C to 85C but no other data.Thanks
Long-term experience with signal relays Fujitsu FTR-B3? - Page 1
Forum section: electronics / projects

author: phofman
author_rank: Newbie
timestamp: March 12, 2021, 07:35:01 am
content: Hi,Please does anyone have a longer experience with the Fujitsu signal relay FTR-B3 in terms of reliability and long-term contact quality? I am looking for a low-cost signal relay as there will be 30+ pieces in the BOM and this model seems to fit the requirements.Thank you very much in advance for any hints and recommendations.Best regards,Pavel.
Long-Term Reliablity of 0603 SMD Fuses Under ESD? - Page 1
Forum section: electronics / projects

author: niconiconi
author_rank: Frequent Contributor
timestamp: June 08, 2022, 06:00:07 am
content: Nowadays there are plenty of miniature SMD fuses on the market, the package size can be as small as 0603, and they can trip at a current as low as 62 mA (with a nominal melting I2t A2sec rating of 0.000075, e.g. See Littelfuse's catalog). It sounds great for protecting sensitive circuits. But I have to wonder, just how reliable are these fuses under ESD stress? Many are made using thin-film technology, which are not known for their robustness. If I put such a fuse on an external port with an ESD diode behind the fuse (so it can protect the board from additional damages if the ESD diode fails short after a large transient, an idea for a toy project I'm currently considering), I intuitively feel that the fuse will probably fail after a year of use. During ESD the current is shunt to ground via the diode, and the instantaneous current across the fuse can be tens of amps.Is there any existing data or experience available on this issue? I suspect not. Zapping the fuse a thousand times with an ESD simulator may be the only way to find out...

author: jbb
author_rank: Super Contributor
timestamp: June 08, 2022, 09:33:49 pm
content: It’s by no means guaranteed, but asking the manufacturer might yield results. Some manufacturers won’t care if you’re not ordering a million, others might say “you know, we should do an app note on this.”Possibly you could do some checks by calculation?- estimate I2t impulse applied by ESD event, compare to fuse opening I2t?- estimate current density in the thinnest part of the fuse and compare to electro migration thresholds (requires knowledge of fuse geometry…)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 08, 2022, 09:58:05 pm
content: Well, offhand, say ESD is a pulse of 10A for 50ns -- that's 100 A^2 for 0.05us or 5 uA^2s. Actual figure is different of course because of waveform, but will be in this order of magnitude. Their spec is 75 uA^2s apparently, so it should be safe. For sure, an appnote on the topic would be welcome; it's close enough that it really won't take much.Think I'd be more worried about inrush; it doesn't take many uF to blow something like that at 5V or whatever.Tim
Longleat - Festival of light XMas Tree - Page 1
Forum section: electronics / projects

author: Wilksey
author_rank: Super Contributor
timestamp: November 30, 2017, 10:02:50 pm
content: How much power and how many pixels do you reckon they use on the XMas tree at the festival of light (Longleat, Wiltshire, UK).Video of the tree can be found here (not my video):If you look at the tree close up, apart from being blinded by the green glint of the LEDs, they look like "neo pixels", or some form of.
Look inside a 50 ghz step attenuator - Page 1
Forum section: electronics / projects

author: nexus
author_rank: Regular Contributor
timestamp: September 09, 2021, 01:06:27 am
content: Hi all,Working on an E4446A i bought that had alignment failures. Naturally front end attenuators are a good place to start.Further testing revealed a faulty 60db attenuator due to contact wear misalignment. A careful disassembly, cleaning, tweaking, and reassembly of the attenuator restored its function and that of the overall instrument which was able to successfully align afterwards.Video to come once I have a change to edit all the footage. Enjoy the pics of these ultra-tiny rf parts in the meantime!

author: nexus
author_rank: Regular Contributor
timestamp: September 09, 2021, 01:29:32 am
content: here is the keysight parts store page for this module:https://www.keysight.com/my/partDetail/33325-60020$2,729.00 new. You can get a used working one on ebay for half price.
Looking at a Filament LED - Page 1
Forum section: electronics / projects

author: harerod
author_rank: Frequent Contributor
timestamp: December 04, 2023, 05:30:35 pm
content: I am a big fan of those "filament" LED-bulbs for E27 sockets. I had a defective one lying around in the office for a while. Today I finally cracked it open and had a closer look at the "filaments". These consist of 28 LED's on ceramic substrate, coated with a luminescent layer that shifts short wave light to longer wavelengths.For initial tests I illuminated the filaments by near-UV light, which looked really cool.Then I tried to light the LED's themselves. This barely worked, since the highest voltage readily available at my desk is 70Vdc. At that voltage the LED's barely lit up, drawing a current below 0mA.The spectrum for the single filament shows the peak for the blue pump light at about the same height as the red light. However, under nominal operating conditions the blue peak would be much less prominent.So, what do we do with this kind of information? First obvious choice would be to furnish a Darth Vader figure with a cool light sword.Or, with Hanukkah around the corner, this may serve as an inspiration for Dad/Son projects to bring some light into your home.Take care with the voltage, though - unless you opt for external UV illumination.Edit: Added UV pump spectrum.

author: Gyro
author_rank: Super Contributor
timestamp: December 04, 2023, 05:52:21 pm
content: You might want to check out some of Big Clive's videos, he's done quite a few on LED filaments...https://www.youtube.com/@bigclivedotcom/search?query=LED filament

author: tooki
author_rank: Super Contributor
timestamp: December 04, 2023, 08:23:26 pm
content: You can get them in all kinds of variants on Aliexpress. I used 3V, 38mm ones to make a giant-digit thermometer. Using the low-voltage variants makes it way easier and way safer to drive them.
Looking for 0.025” header pin pcb receptacle. - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: May 09, 2018, 02:25:25 am
content: Those strips of header pins 0.025 inch square and 0.1 inch spacing, what I want to be able to do is plug a short strip of them directly into a pcb. I am looking for some kind of hollow single pin receptacle that will drop into a pcb hole and sit almost flush with the surface, with some kind of spring claws inside similar to the individual holes in a turned pin ic socket. Hopefully also the receptacle will have a hole right through so the square header pin can poke through if necessary. A moulded plastic version is no good because it has to be very low profile. Any ideas?

author: dcarr
author_rank: Regular Contributor
timestamp: May 09, 2018, 03:28:45 am
content: Give this category on Digi-Key a look:https://www.digikey.com/products/en/connectors-interconnects/terminals-pc-pin-receptacles-socket-connectors/324?k=&pkeyword=&pv2295=2&FV=ffe00144&quantity=0&ColumnSort=0&page=1&nstock=1&pageSize=100
Looking for 0.1" crimp connectors for LED strips - Page 1
Forum section: electronics / projects

author: tom66
author_rank: Super Contributor
timestamp: September 20, 2015, 09:30:16 pm
content: I have some WS2812B LED strips which have contact pads similar to this:http://kutop.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/5/v/5v_programmable_ws2812b_rgb_5050_led_light_strip_1.png(except mine do not have holes.)The problem is the strips are very flexible, and this makes a reliable connection difficult (the heavy PCB that needs to bond breaks off the solder pads often, and every time I have to sacrifice an LED...)I found these - perfect for what I need - but the problem is the seller is probably not going to sell me a few (20pcs) - I've asked, but don't expect a responsehttp://www.alibaba.com/product-detail/3pin-wire-solderless-connectors-work-on_60288063576.htmlDoes anyone know of any alternative sources for these types of connector?Thanks

author: David_AVD
author_rank: Super Contributor
timestamp: September 21, 2015, 02:36:32 am
content: TryRay Wu on AliExpress.
Looking for 1.00 mm pitch Header manufacturer - Page 1
Forum section: electronics / projects

author: qno
author_rank: Frequent Contributor
timestamp: February 29, 2012, 02:32:57 pm
content: Hi all,I have a Logitech 910 webcam.I am looking for the manufacturer an preferably the type of heater that is used for the USB cable to board connection.It is a 4 pole 1.00 mm header.It is not a Molex Pico Clasp type. That one does not fit.I looked at Samtec It looks a bit like the S1SS series 1.0mm pitch.Problem is Samtec does not list a 4 pole version in the catalog.Please help

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 29, 2012, 03:14:25 pm
content: Try JST - very popular for far-East stuff, but may be hard to find in small qty unless Digikey stock it.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: February 29, 2012, 04:06:03 pm
content: http://www.harwin.com/M40-301-Connectors-Single_Row-family.htmlperhaps