Ask an Expert Forum - Recent Threads

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

Any Farnell H05VV-F cable 2x0.75mm2 rating 10A

khang2016 — Wed, 25 Feb 2026 03:41:58 GMT

Are any cable code H05VV-F ampere rating 10A

Cheap Alternatives to Flex Sensors for Gesture Glove Project

Aniket_kumar_raj — Wed, 11 Feb 2026 13:54:20 GMT

Remember when I asked about a material for a glove that can detect finger movement? The best answer I got was magnet-type stuff, but that’s actually not cheap. I tried going for flex sensors, but getting 5 flex sensors is out of budget for my school science exhibition team. I decided to try Velostat, but I’m not sure if it will work.

What do you guys recommend? Also, what can I add to make this a killer, jaw-dropping project? This is my last school project where I can really flex my tech skills (or maybe our team’s tech skills 😄).

The exhibition is on the 28th, but my team is kind of lazy, and shipping takes too long for these things. It’s for National Science Day, so I really want this to be amazing. Please help me make this project next-level!

Also, if you have any other cool ideas (even unrelated ones), feel free to suggest them. The idea hasn’t been finalised yet.

Need help designing a flow sensor for marine application

Former Member — Wed, 11 Feb 2026 11:37:07 GMT

I want to develop a flow sensor for sea water hose flow rate. It will be used to provide information to be able to shut off and on a water pump. I'd say a clamp on style able to be mounted on a short piece of pipes of various diameters. Any engineers would like to help or guide me in the right direction?

AI is helping me but I'm not an engineer. I have found out that I'll need transit-time transducers (non-intrusive) and a flow rate of 5-100 GPM.

The transducers will be mounted in a short piece of Schedule 80PVC (about 3-4" long) and threaded on both sides for easy installation. There is a product that already exists for my needs but it is Propriatary. (Electrosea "ClearVis" sensor). Basically I'm in need to know the flow rate of sea water so when it is lower than, say 13GPM, send a signal to shut off the water pump. In the available Electrosea system it is used for it's operation and depending on the water flow rate it will introduce current so create cholrine in the sea water to prevent biologiacal fouling. Eventually I'll get there, right now just looking to design that sensor.

Any takers?

Thanks

Mario

Question hdds 2.5"

cloudff7 — Thu, 05 Feb 2026 18:16:40 GMT

Are the electromagnetic fields and waves generated by a large 29" CRT TV (turn ON) and Desk Fan (turn ON) at a distance of 2cm from a 2.5" HDD (turn ON) sufficient to penetrate the HDD and cause interference in the arm and head movements, as well as read and write errors? i has old 2010 and new hdds 2.5"

Looking for an LED driver recommendation

colporteur — Mon, 02 Feb 2026 23:29:54 GMT

I'm looking for some suggestions on a replacement LED driver circuit for the one above..

I have 10 common cathode tri-colour LEDs I need to drive. I banged out this transistor circuit to isolate the LED's from the Arduino. A HIGH output from the Arduino should light the LED. I've used the transistor circuit on a small scale for driving LEDs. My formal training was in electronics but 20 years ago my career forked to computer networks as a system administrator and the electronics became a thing for hobbies.

I then thought there has to be an easier way. I started newark searching for possible drivers but my lack of practical experience in this area makes it tough. I'm looking for something simple that takes the load of the microcontroller. I found this SN74HCT245N bus driver and thought that might work. Four twenty pin IC's would give me 32 drivers. I need 30 in total. Simple IC's verses all the individual components would make PCB assembly definitely easier.

This is not high speed switching. It is simple on and off control for LED's. I'm hoping the folks that hang out here and do this sort of stuff all the time would have a recommendation for there go to circuits for this sort of thing.

LT1712: Need help understanding and modifying this oscillator

rsjawale24 — Sun, 01 Feb 2026 17:39:51 GMT

I'm in need of an analog circuit that can generate a square wave output of 20MHz. My first thought was to use a schmitt trigger inverter with a crystal, but then I thought of using a fast opamp to make it more challenging and a fun to work on project.

I came across this circuit made using LT1712 4.5ns comparator from Linear Technologies (now ADI). The circuit below generates a square wave output with a freq. of 1MHz which is filtered to obtain a sine wave of 1MHz. It uses a series resonant crystal to generate a stable 1MHz signal as shown in Fig.1

I modified the circuit, by replacing the crystal with a 20MHz one and R3, C1 by using another circuit given in the datasheet of LT1016 for 10MHz to 25MHz signal as shown in Fig. 2. I made a PCB to test the chip. However, my output frequency is around 10MHz with a distorted square wave output. I have tried the circuit in LTspice where it gives proper 20MHz output.

Hence, I need help in understanding how the series resonant crystal circuit is working, why the 210 ohm resistor? and how the R3 and C1affect the output freq? As the values are both different in the two circuit diagrams. I have also posted the LTspice circuit simulation and output as well as the measured output of my PCB.

Fig. 1: LT1017 1MHz square wave gen

Fig.2: LT1016 10MHz to 25 MHz generator

DSO output

Marvell PHY 88x3220, FW download

liusean1 — Wed, 28 Jan 2026 20:33:38 GMT

I am trying to bring up the PHY 88X3220, here are my questions:

(1) the FW has to be download in order to bring up the link?

(2) Where I can get the FW? is the FW version in the MTD_API_Relase_4_2_0 is valid for 88x3220?

Thanks.

Soft Keyboard

Nasser019 — Tue, 27 Jan 2026 16:43:31 GMT

Why is there no cell phone where the Del key is present in the soft keyboard?

Green laser diode

Hayden40 — Mon, 26 Jan 2026 02:41:56 GMT

Anyone kno which green laser diode will project a 90 degree pattern parallel to the floor to reveal dust

Reading Component Datasheets!

cespecialist — Fri, 23 Jan 2026 09:18:03 GMT

I’m planning a practical post on how to interpret component datasheets for real designs—what the different parameters and graphs are actually telling you.

Before I start, I’d like to get some feedback: would this be useful to the community?

Raspberry PI 5 OS version?

Rory_D — Mon, 19 Jan 2026 23:46:55 GMT

What is the version of raspberry pi OS that is shipped with the Raspberry Pi 5 starter kit RPI5-STARTERKIT-8GB-US?

Failing to wire PL signals to physical pin on Zedboard 1CG

jaksch1 — Wed, 14 Jan 2026 15:35:03 GMT

Hi, I am stuck with my little project here and looking for help. The situation

I have successfully created a block design which uses the axiDMA IP and loops it through a FIFO back to the SW. This is required by an example program in Vitis I am using as a foundation to use the DMA, with my setup I got the example to execute succesfully.

Now where I ran into issues: I have created ant tested a custom IP which serializes these 32b values from AXI to a pin which I want to route to an external pin. The IP works which I validated through a testbench and even on the MPSoC using an ILA, but I cant see any reaction on the pin.

I have reviewed the implemented design and the net is properly generated (design connected to output buffer and output buffer connected to external pin).

Am I missing something, which parts of the flow could cause errors like this? Is there maybe some configuration required through Vitis?

Some of my resources:

Constraint:

set_property PACKAGE_PIN F3 [get_ports x_gpio_serial_clock_0]
set_property PACKAGE_PIN F2 [get_ports x_gpio_serial_out_0]
set_property PACKAGE_PIN N2 [get_ports x_gpio_serializer_active_0]

set_property IOSTANDARD LVCMOS18 [get_ports x_gpio_serializer_active_0]
set_property IOSTANDARD LVCMOS18 [get_ports x_gpio_serial_out_0]
set_property IOSTANDARD LVCMOS18 [get_ports x_gpio_serial_clock_0]

Top level instantiation:

entity design_1_wrapper is
port (
x_gpio_serial_clock_0 : out STD_LOGIC;
x_gpio_serial_out_0 : out STD_LOGIC;
x_gpio_serializer_active_0 : out STD_LOGIC
);
end design_1_wrapper;

architecture STRUCTURE of design_1_wrapper is
component design_1 is
port (
gpio_serial_out_0 : out STD_LOGIC;
gpio_serializer_active_0 : out STD_LOGIC;
gpio_serial_clock_0 : out STD_LOGIC
);
end component design_1;
begin
design_1_i: component design_1
port map (
gpio_serial_clock_0 => x_gpio_serial_clock_0,
gpio_serial_out_0 => x_gpio_serial_out_0,
gpio_serializer_active_0 => x_gpio_serializer_active_0
);
end STRUCTURE;

My custom Serializer in the block design:

What sensor can I use to determine rotation?

Aniket_kumar_raj — Tue, 06 Jan 2026 11:12:38 GMT

Guys is there any sensor online that is small to fit between two finger joints and calculate how much degrees its turned, i am lanning to make a glove that has ability to see at what position fingers are turned to.

I thaught of potentiometer but its too large to fit between finger joints, also what i men to say is that i am making a glove like thing where a sensor is needed which can be attached at finger joints to see ho much is it turned

Solder able prototype board for 5A

flows — Fri, 02 Jan 2026 19:10:20 GMT

Hello,

I need to create an IoT project that will automate something in my life. So i am making a automatic sunscreen controller which will make the screen go up or down based on the weather.

Now im almost finished with the project, it was time to connect the electronics. I am no expert at electronics so i looked up if i can just connect the nema 17 stepper motor to the power supply via the breadboard. As of my knowledge the Nema 17, at its peak, takes 1.7 amps per coil, it has two coils. So thats at most 3.4 amps. I have a power supply to power everything of 12V and 5A. It will melt the plastic of the breadboard with that current.

So i was thinking maybe i could just put it on a solderable prototype board which makes it more secure, safe, and i will gain some extra points (yes thats something you can score on).

But i have no idea how i can know what prototype board can handle that current. Its also not stated on the sellers page.

On a arduino form someone recommended this prototype board: https://www.amazon.co.uk/Gikfun-Solder-able-Breadboard-Arduino-GK1007U/dp/B07D7PMCG5

But when i ask AI it says the board will also melt. Am i being misled by AI 😭?

Picture of system:

Note: in this picture i use a expansion board because i though i couldn't directly connect the DRV8825 to the breadboard.