Ask an Expert Forum - Recent Threads

Looking for an oscilloscope / logic analyser, maybe usb?

stanto — Sun, 21 Jun 2026 12:44:19 GMT

Anyone using a portable/handheld oscilloscope/logic analyzer?

Im looking for recommendations of something to pick up.

Ideally with capabilities to hook into python or coding libraries over USB too.

Output current, LED Color, Wattage LED Driver

rgovande26 — Tue, 16 Jun 2026 15:52:52 GMT

I am new to this group.

LED driver is new for me and I am learning about it now!

I recently started working on 8' LED tube light. It uses HOSSONI LED Driver (Ballast) SDC96CS200V48DL1A. I believe this is a Constant Current Driver.

t has following:

Input voltage measured is 120Vac
Output: 36-48Vdc, Actual No-load voltage: 55Vdc
3-wires are connected to the LED lights
3 position switch to select the color 5000-4000-3500K
Aux Output: 0-10Vdc (Not used)
0-10Vdc for Dimmer So, a non-dimmable LED Driver should work.

Questions:

A 3 position switch is used to set the color. Does this switch actually changes output currents to 1150mA, 1500mA, or 2000mA?
Does Higher the output current mean higher K value?
There is another switch for Wattage setting; 90-68-48W. What's the meaning of this? Is this the power wattage available or applied to the LED light?
Does the change in output current changes above wattage (90-68-48W)?

Please let me know if more information is required from my side.

Thanks

Bosch Plena LBB1935 schematic

jsmartins — Tue, 02 Jun 2026 23:11:46 GMT

Hello,

I have two Bosch Plena LBB1935 amplifiers that need repair. On the main bord there are some resistores with burn signs but i will nee the schematic to find the right values. Anyone have the circuit that can share a copy?

Thanks

José Martins

Do I need to add more components to make this transformer safer?

HKPhysicist — Mon, 01 Jun 2026 16:14:36 GMT

Dear all Electrical and Electronic Engineers,

I own an audiophile grade Sony blue disc player. It accept 115V AC.

Then, I bought this transformer which transforms my wall outlet 230V AC to 115V AC, which is then connected to my Sony Disc Player.

https://hk.element14.com/triad-magnetics/vpt230-110/transformer-toroidal-2-x-115v/dp/1785731

Do you think whether I need to add additional components to make this transformer safer to work? I have already bought another beautiful aluminium enclosure to contain it. 😀

The main point is - it is an audiophile grade system. Additional components may degrade the final sound quality.

So, there is a dilemma.

Clarification on AD7192 System Calibration Input Span vs Observed Full-Scale Behavior

Jay_Instrument — Sat, 30 May 2026 06:48:15 GMT

Hello,

We are currently evaluating the AD7192 ADC as a replacement for the obsolete CS5532 in our load cell application.

With the CS5532, after system calibration, we were able to achieve full-scale output at an input of 10 mV. While testing the AD7192, we are observing behavior that does not fully align with the system calibration input span specifications given in the datasheet.

Our configuration is as follows:

Reference voltage (Vref): 5 V
Gain: 128
Calculated full-scale input range (FS): 39 mV

As per the datasheet, the allowable input span for system calibration is:

Minimum input: 0.8 × FS ≈ 31 mV
Maximum input: 2.1 × FS ≈ 81 mV

However, our load cell has a maximum output of 10 mV, which is significantly below the specified minimum calibration span.

Observed behavior:

We tested inputs at 10 mV, 15 mV, and 30 mV.
We begin to observe full-scale counts starting at approximately 15 mV.
This is notably lower than the expected ~31 mV minimum based on the datasheet.

Questions:

What could explain achieving full-scale counts at ~15 mV, which is below the specified minimum system calibration span?
Is this behavior valid and reliable for production use, or could it lead to accuracy or stability issues?
Given our load cell output (max 10 mV), would you recommend proceeding with AD7192, or should we consider alternative configurations or devices?

Additionally, could you please connect us with an Analog Devices application engineer to further investigate and discuss this issue in detail?

We would appreciate your guidance in understanding whether this observed behavior is within acceptable operation limits and suitable for long-term use.

Has anyone worked on Integrating with openplotter for AIS ADSB marine Ham band monitoring?

KariR — Wed, 20 May 2026 12:33:57 GMT

I'm interested in replacing my sdr dongles with this kit to integrate AIS ADSB Marine and Ham band monitoring. The capabilities of the kit fit nicely and will allow for simultaneous wideband monitoring over a very wide spectrum

Would someone be interested to create Ben Bulsink's NFC Game Board?

Luka851 — Mon, 18 May 2026 13:10:51 GMT

Hello everyone,

I wanted to make a custom smart chess board and I came across to Ben Bulsink's open source technology on nfcgameboard.com. Following is a demo video of his creation: https://www.youtube.com/watch?v=4qKndjF60Js&t=12s.

I wrote to him, and together we decided to upgrade the device and use the newer PN5180 IC instead of the CLRC632 IC that he used in the prototype. We used Playfultechnology library for PN5180 and encountered issues, such as the library wasn't detecting multiple tags. We have solved and improved that library, and that challenge now is solved, however we now encountered next issue which is connecting the IC to the external antenna. When we cut the PCB antenna traces on the module the IC stops to respond correctly, such as returning EEPROM and seems to get stuck in the loop even before it reaches communicating with the antenna. We don't know what may be causing this. Does anyone has any idea on it and how to fix this?

My next question is will there be anyone who would be curious enough to also try to recreate the improved board? We want to create an open source technology - hardware as a sandbox, so anyone can make the board, and then write their own code to create any kind of the game on top on it, whatever they want, perhaps share their game on the common platform with other players to download and play their games. We are communicating through email and having more brains working on it will make things easier, faster, and thought maybe ask if anyone was interested to join, will be here to help and explain, what I know.

https://nfcgameboard.com/schematics/ - gives the idea, schematics, pcb, and similar, but for CLRC632. in short, we will make 15x15 grid board, using multiplex antennas - each antenna being 15x30mm, we will have then 30 antennas (15 rows, and 15 columns), instead of 225 small antennas, a matching circuit and one PN5180 IC.

I want to build submerged arc furnace with deionized water. I would like to know how to build it. There is no plan available on google.

manojroy123 — Sun, 17 May 2026 18:02:24 GMT

Some of the problem with deionized water is. Once it is opened it quickly absorbs Co2 from air. I would like to know how much will it affect the experiment setup. I am trying to extract graphene and carbon nanotube from this experiment.

ERSA soldering iron tip suddenly un-tinnable

davebullockmbe — Sun, 17 May 2026 09:53:03 GMT

Hi I have an ERSA I-CON PICO solder station that has served me really well for several years when suddenly the 'pencil' tip has become un-tinnable.
It is the :-

://uk.farnell.com/ersa/0102pdlf04-sb/tip-soldering-iron-pencil-0-4mm/dp/1203967

A 0.4mm pencil tip which is great for getting into solder the tiny legs of SMD IC's.
I had used ERSA Digital 2000A's for years and years and then bought two of the I-Con Pico's (one for me and one for my son) a few years ago as we are both into SMD development and assembly.
I have never had a problem with the tip of the iron until recently when I just couldn't get the very tip of the bit to accept solder.
The solder station is not used on a daily basis (hobby use only) and is only switched on when required, I always use the supplied brass (Brillo pad) tip cleaner and this has kept the tip clean and operational until now.
Inspecting the tip I can see that it is still sharp with no visible pitting or corrosion, however it has a grey appearance instead of a 'silver' tinned area right at the tip.
I imagine that these tips have a special coating and shouldn't have anything abrasive applied (sandpaper/file etc) so I am wondering if the tip can be easily restored, or has it reached the end of it's life??
Any suggestions would be gratefully received, as both solder stations are suffering the same problem.

Thanks ...Dave

Help identify replacement for burnt out component

stanto — Sat, 16 May 2026 15:55:41 GMT

I have been asked to repair the charger for a family member's E.C. Cutter Electric Scissors Kit. The charger for it is supposed to output 7.5v at 1.2a and it outputs 11v and buzzes. It's completely sealed, so it's going to be replaced.

However it took the charger with it, upon opening it should a replaceable component, but I'm having trouble knowing what to look up.

Here's photos of its insides:

I'm presently in Norway, so finding parts here may be tricky and I'll have to bring it back to England to pick something up!

I'm expecting some of the diodes to have failed after checking them in diode mode on a multimeter, and the burnt out component may be a radial inductor?

How to Calibrate and Measure the Hysteresis (Deadband) of a Pressure Switch Sensor?

sebrinadabe594 — Fri, 15 May 2026 04:17:30 GMT

Hi everyone,

I am currently designing a pressure monitoring solution for an industrial pneumatic control system. I'm using a mechanical pressure switch with a setting range of 0.2 - 2.0 MPa.

My goal is to ensure an alarm is triggered when the pressure reaches 1.2 MPa, but I am currently facing issues with poor repeatability and contact chatter. I want to keep the hysteresis (deadband) within 0.1 MPa to prevent the compressor from frequent "short-cycling."

My current toolset includes: a digital multimeter, a manual pressure pump (with an analog gauge), and some basic wiring tools.

My questions are:

How do I accurately measure the hysteresis? I noticed that the pressure point where the switch "closes" is different from where it "opens." Is this normal? How should I record these two values to calculate the deadband?
How can I reduce false triggers caused by electrical noise? The switch is connected to a PLC digital input. Due to high-power motors nearby, the PLC often receives false trigger signals. Should I install an RC snubber or resolve this via software filtering?
Choosing between Normally Open (NO) and Normally Closed (NC): In a safety system, which wiring configuration is generally recommended? If a cable breaks, which setup allows the system to fail-stop more safely?
Impact of environmental vibration: The pressure switch is installed near a pump body with significant vibration. Will vibration shift the setpoint of the switch? Do I need to perform a remote installation using a capillary tube?

wd mybook essential NO GO

acdc90 — Wed, 13 May 2026 10:40:24 GMT

Hello

I have just pulled a friends WD 2tb mybook apart because nogo

standard looking sata drive

with USB adaptor board

this unit has power switch on rear. this does nothing

there is a rubber block that has damaged adaptor board .

(black marks near rubber and black feed throughs)

i have tried the hdd on w-10 pc (drive spins up)

disk manager showed the model number

but explorier did not show the drive

i believe the drive is encoded to the adaptor board

ic on board
RT8284

output of L6 to 3 caps has 5v on them

BA1P1F, 4619

JMS538S, 1131, QGCA2, E73D60017 This ic has no volts on it,

power button also has no volts on it and connects directly to jms538s

power sw pull up ? r41 witch connects to c70

this line also connects to 4 pins on jms538

this line also connects to vcc on 25x20blnig (memory)

I have been un able to find a data sheet for this IC

has anyone seen this fault before

on the weekend I will try putting 3v on this point,

How to measure an impedance of an nfc antenna

Luka851 — Tue, 12 May 2026 13:41:08 GMT

Hi,

I want to make a custom dimension - 20mm x 320 mm - external antenna coil for PN5180 NFC Module/Chip.

To do this I need to design an antenna that has inductance of 0.8-3 microhenry, and then a matching circuit to match with the chip/s 20 ohm load impedance at 13.56 MHz.

I only have an oscilloscope and a signal generator.

My questions are,

1. How do I measure inductance of the following antennas

2. How do I measure impedance on the pn5180 module, and when I do, the result should be 20 ohm, right?

3. Can I measure inductance of the antenna on the pcb? I should disconnect the matching circucit to do it, right?

4. How do I disconnect the pcb antenna from the module and connect to it either of two coils from photos above.

Non streaming media player for photo slideshows with chapters

pixelpine — Sun, 10 May 2026 19:01:16 GMT

I am an advanced beginner when it comes to electronics and computing and I need some help to know if what I am looking for is indeed out there or not. I just started my own very small business and I have a client I am currently working with on a large archival project. I am trying to find or put together a specific media player or media box for his project. I know I can put together a Raspberry Pi that would work but it comes with extra components that aren't needed. It might still be the best way. I'm hoping to stay under $100 to make it affordable for my client as well.

PROJECT SUMMARY:

My customer has about 4000 family photos that I am scanning into Tiff and Jpeg and then creating photo slideshows.

THE PROJECT:

19 different projects of 100-500 photos each.
Each project is a different family topic and a different slideshow.
Each project is broken down into smaller topics that are separate folders for the images and different chapters in the slideshow.
Customer will be ordering 11 of this item. (If I can come up with a good product, I foresee being able to sell more)

THE GOAL:

All of the images and slideshows onto one archival quality device.
Play the slideshows with the chapters from the device to the TV using HDMI - Plug and Play - no streaming or internet required.
The above could be done using VLC media player installed on the device and playing .iso files
OR I can create a custom .html file or simple program interface that will automatically open on the TV when the device is turned on and plugged into the TV using HDMI.
No other applications or apps visible to the customer.
Ability to use a remote on the TV
Also able to open the scanned images on a computer, using USB, to alter, make prints etc. with the photos

SIZE: Raspberry Pi or Boxy gadget size

Okay to use Flash drive or SD Card as the storage device and plug into the Media Player.

I'm looking forward to any input! Thanks!

I need opinions on improving my nice ABS enclosure.

HKPhysicist — Wed, 06 May 2026 16:54:54 GMT

Dear Engineers and Experts, 😊

I have found a very nice enclosure to contain my air monitor and sensors.

The only drawback of it is - there is a large opening (perhaps for ethernet) which is redundant for my design.

So, could you suggest a way to cover or patch this rectangular hole (inside the blue lines) so my end-users cannot see or touch the electronics inside?

The manufacturer claims that this enclosure is made from ABS plastic.

Tooling I have - a Bosch Dremel 3000 mini drill with wheel cutters, a mini table vice. 😉

making a circuit board for IDE to USB converter

safia_fatima — Wed, 29 Apr 2026 19:47:51 GMT

I am trying to make an external hard drive casing for an IDE HDD. The hard drive should connect to the laptop using a USB cable. The power comes from a molex connector in the IDE drive which is interfaced with a serial port for the power supply adapter. I need the schematic for this and step by step process on how to build it on a perf board, for example. I have an existing converter but it seems to have a short circuit and I cannot trace the problem. The market has a number of converters, but I would prefer to build one to learn how the circuit works. Please kindly guide me on the best way to connect the hard disk.

TDK lambda DC-DC converter I6A4W010A033V-001-R

shabaz_atai — Mon, 20 Apr 2026 10:21:18 GMT

Hi all,

We have bought I6A4W010A033V-001-R to power a Intel optiplex CPU that require a 20V and 6A power.

We have succeded to tune the outupt voltage to 20V from a 24V input using a potentiometer over the trim pin Vout -ve pin.

Later we tried to power the CPU from this converter which we haven't succeeded. The device itself is not booting up. The power led over the start button is glowing in amber which should be white if it has proper power input.

Unfartunately we have only moduel for testing purpose.

What could go wrong? Do we need any extra cicuitry to make this work? Does the amp rating of the potentiometer used between the trim pin and ground also also matters for the amp capacity of the module?

We have tried with different capcitors in both output and input. The power adapter of the CPU has the sense line also aprat from the DC +ve and -ve. We even tried connecting that to the sense pin of the DC-DC converter. Nothing helped us.

Summing amplifier using opAmp tutorial?

ronyd — Sat, 18 Apr 2026 22:07:30 GMT

Reviewed tutorial "Explore Working Applications of 8 Different Op-Amp Circuits" (https://www.youtube.com/watch?v=aR9ILhbG4AE&t=317s)

@12:14 he indicates turning on the Reference Voltage which drives the opAmps input. Is this Reference Voltage a voltage divider connected to Non-Inverting input (pin 3)?

I would like to know as a DIY hobbist which programming language should I opt for programing DIY Development board

manojroy123 — Sun, 05 Apr 2026 06:10:02 GMT

I would like to know as a DIY hobbist which programming language should I opt for programing DIY Development board. I am intrested in building test instruments that requires use of GUI and voltage measurement and also use of Raspberri pi SBC for some projects and I would like to makes thoes project open source.

My design tools ...

John_Oliver — Wed, 25 Mar 2026 14:46:23 GMT

Can I get an API Key from you so that my design tool can scan your inventory for parts, data sheets, footprints, schematic symbols, pricing, and availability?

What are the advantages of a benchtop digital multimeter when compared to a portable one?

obones — Wed, 18 Mar 2026 16:10:55 GMT

Hello,

I already own a portable multimeter that I am applying for these use cases:

90% : continuity testing (bip bip)
9% : battery/coin cell condition
1% : debug a running circuit to see if an output pin is on

When the signals that I want to measure vary rapidly, I use the oscilloscope to graph them, in single shot most of the time.

As I've been given the opportunity to choose new gear, I'm considering my options, one being GW Instek Bench Digital Multimeter

However, I'm not sure that I would put it to good use, hence my question: What are the advantages of such a device?

Thanks for your insights.

what do the zeros mean on this transformer datasheet?

SensoredHacker0 — Tue, 17 Mar 2026 17:32:24 GMT

Im thinking about buying this transformer,
but the schematic symbol has something I don't recognize, and I want to be certain to buy the right thing for the right application

The application is that I want to convert 208VAC to 120VAC. in the 750kVA to 1kVA range
The part I am confused by is what the zeros on either side of the primary and secondary mean.

To wire the primary, I would use A/B phase.
I think what the datasheet is saying is that if I have a neutral I would wire it there, not that I can't use 2 phases.
I'm just trying to verify.

www.solahdsales.com/.../ce1500mc.htm

mplabx 6.20 is driving me crazy on fedora 41

madthescientist — Sun, 15 Mar 2026 13:05:27 GMT

I am trying to start a project using mplab 6.20, pickit 3 and pic16f877.

I am using C language. I have Pragmas set, i defined names for each pin and i could set which ones are inputs and outputs.

i did declare 3 int variables.

The problem i have is: once i get in the void main(void) {} stage, i can write a simple if{} routine assessing whether 2 variables are 0 or 1 and set the state of a the third one. However, if, instead of those variables i try the same with the pin names to read them or write on off (0 or 1) to them i get inmediatly a spree of red marks in the left and error hints claming unrecognizing tokens. it only happens when invoking named pins as variables, not actual int variables.

I did other job last year using the same setup and a pic16f819 and after some learning curve it works.

May i be forgetting to set something up in the project to use named micro pins as variables?

Why is the Schottky diode being used in control circuit?

Humaninsane — Mon, 09 Mar 2026 04:35:01 GMT

Why is the Schottky diode being used in control circuit? and why is the 470nF cap is added at that voltage divider output? how is the Cap value 470nF calculated?

Multicomp Pro soldering tip set's compatibility with Milwaukee Soldering Iron

Viking2026 — Fri, 06 Mar 2026 07:14:30 GMT

Hello, I’m trying to determine if the Multicomp Pro MP011242 soldering tip set is compatible with the Milwaukee M12 soldering iron (model 2488-20). Any idea?

MP011242 MULTICOMP PRO, SOLDERING TIP SET, 5PC | Farnell Norge

milwaukeetool.ca/products/details/m12-soldering-iron-tool-only/2488-20