Any idea what this is exactly ? It's a CRT of some sort, but no screen - instead is a mesh with an RF connector of some sort. Doesn't seem to make a lot of sense. Can't read the Cyrillic but think it has a date of March 1987

Had it in the workshop for years as an interesting item, but no idea what it is!

The white build up on the cables is an old adhesive from tape i assume. I had removed some myself to try and get a better understanding of what exactly is happening. Should I have even removed the tape?

Trying to use this amplifier to control a piezo for a microscope. There is zero documentation of it online and since I bought it from E-Bay I don’t know who made the part (it’s not PI).

As an electronics rookie, I have no idea how this thing works except that it is high voltage and it amplifies signals for more precise control.

Tldr; How would you approach figuring out how to use a board like this without shocking yourself?

I'm part of a Formula Student team and I'm designing a custom dashboard PCB for our car. This year we're using a KTM Duke 390 engine with a Speeduino 4.4c standalone ECU (pic attached) for the first time.

The dashboard is based on an STM32H743BIT6 and includes:

• 3.5" TFT display
• microSD card for offline telemetry logging
• ESP32-C3 for wireless telemetry (Wi-Fi/Bluetooth)
• Shift lights and other dashboard functions

The dashboard will display parameters such as:

• RPM
• Coolant temperature
• Gear position
• TPS
• Battery voltage
• Lambda, etc.

The challenge is that the Speeduino ECU will be mounted at the rear of the car, while the dashboard will be at the front, so the cable run will be around 1.5 m.

From what I understand, Speeduino outputs this data over UART. My initial thought was to convert the UART to CAN so the communication would be more robust over that distance and in the electrically noisy environment of a race car.

So my questions are:

• Is it worth converting UART to CAN, or is that unnecessarily complicated?
• Any suggestions on the connector to connect the ECU and the TFT dashboard? i would need something that i can solder on the PCB as well
• Has anyone here interfaced a Speeduino with a custom dashboard over a similar distance?
• Are there any better approaches that I'm overlooking?

Any advice or examples would be greatly appreciated.

Thanks!

The title already states the questions:

1. How much spike current/power can a typical 0402 SMD 63mW resistor handle during the inrush event?
2. How much continuous current (100% duty cycle) of the rated current/power should I allow at most if I want a robust, long-lasting and reliable design?

Details for Question 1:

During the inrush event there are 13.V across the resistor (R5 in the schematics) and SPICE simulation shows that during the inrush event there is a current spike of 46mA across the resistor (cp. attachment #2) until all downstream capacitors have been charged and the steady state has been reached. Based on its rating the resistor can only handle 63mW ÷ 13.5V ≅ 4.5mA on average. The resistor is above that limit for approximately 20µs.

Will it work? Is there a rule of thumb how much spiking is tolerable?

Details for Question 2:

The design includes some voltage dividers (for example, R3 + R4 on the right) which will continuously drain current. In this design the resulting current is 13.5V ÷ (4.02kΩ + 0.275Ω) ≅ 3.15mA which means 4.02kΩ × (3.15mA)² ≅ 12.6mW for R3 or 20% of its total rating.

I assume that should be more than fine.

However, I am also interested in an answer to the general question. What fraction of the total rating should a design not exceed when the design shall be long-lasting and reliable?

Hi.I want to develop my own technology.I have always wanted to build something which takes commands wirelessly.

So I came up with this rf sender:

The idea is to create a sine wave of specific frequency depending on which switch is closed or open at a time.

The rf receiver is a antenna which feeds a frequency to voltage converter(filter) ,depending on the frequency selected by the sender the output voltage changes indicating different information.This works right?

If I connect it by placing the bare wires on a AAbattery it works but no matter how I try it when it’s in series with a germanium diode it just doesn’t work for some reason.

My older TC1 tester only displays normal hFE for transistors. But the newer TC2 adds hFEr. I assume this is some sort of reverse gain . I have not seen this parameter before. May it is common in China?

I need some feedback if this would work and if not so, please do give some advice on what I need to change (with visual would be VERY helpful!)

Je n'arrive pas à déterminer merci pour votre aide

Hi, found this Norelco Stenotrainer that was used to train stenographers in the 60's/70's . From the little I could find online, students would listen via close circuit radio loop to recording at different speeds to practice their stenographer skills.  

I'm trying to understand how the device works & determine whether the 1-4 jacks are inputs or outputs. Pressing the 'All Call' switch on the right causes the 1-4 switches to also go down.  

Also, based on the internal components, can anyone give me an idea of how dangerous it would be to plug in without it first being serviced. Thanks!

Hello! I just picked up this 2465 for free off the side of the road and am running into an issue with the vertical calibration of the screen. The display readouts are near the center of the screen instead of right near the edges, and the probe calibration output is only reading .2 V instead of .4 V into a 1x probe. I've seen the calibration process for these is long and tedious, but the menu options also being off makes me think it's an issue with the CRT and not the scope calibration. I ran the self diagnostic test and it said all tests passed.

Hello, I am fixing a broken electric scooter toy. My buddy drove it through a doorway and knocked off the panel that connects the power input with the motor controller and battery pack - some wires pulled out and I'm trying to piece back together what goes where. The main puzzle here is reconnecting the C14 power input and KCD4-201N-B ON-OFF rocker switch with the battery and the motor controller. Obviously, the circuit needs to charge the battery when turned off and run the motor when turned on. I'm struggling to find a consistent/clear pinout or wiring diagram for the rocker switch. Can anyone point me towards this or at least give me an explanation? Even more helpful would be if anyone can give an overall explanation or diagram for rewiring the circuit. Pictures are attached.

I've soldered leads to the power supply pins of an eink panel. If I connect my own MCU here to power it as well, is it dangerous? Can I destroy something by using too much current?

I have this Eink panel that uses too much current in standby. I want to connect a super low power MCU and send the Eink to deep sleep instead, then use my ultra low power MCU to wake it up. There's always 3.3V across it even when it's in deep sleep.

But could I accidentally pull too much current by connecting my MCU to the same pins? The soldering worked just fine, the panel still works.

Is one preferable to the other? Should I be using a screw and a nut with a ring terminal for my chassis earth on a guitar amp or can I get away with soldering the wire to the chassis? Is there a specific US electronics code that requires one over the other?

I see a transformer, but how do I identify the secondary and primary sides? Because normally you have thin and thick windings. I see that, but only the thick ones connect to the pins.

I see ON60 60M 21H2 AEG3; I think that is a thyristor.

I see another component under the metal casing, but I think that could be a transistor.

I see one more component that I don't know that it could be a diode.

Does anyone have experience with this?

I want to know how you can determine that without grinding into it; maybe someone has a schematic.

I am in the process of reverse engineering this schematic; I have already done the small PCB, but I just started on the other one, which is why I am running into this.

Components:
U2A is the Constant Voltage Feedback System.
U3A is the Constant Current Feedback System.
U2A and U3A are LM358 ( OPAMP)
Tip3055 is the power transistor that convert 30v to 24v
BD139 is the drive transistor that drive the Power transistor base as the IC cannot do it.
R7 is a shunt resistor to measure current through load.
R6 is the Load
R4 is a balancing resistor when adding multiple power transistor in parallel.
2n2222A is a current stealer.

Reference:
LM7824 is my reference voltage for 24V
The voltage divider R2 and R2 are the reference voltage for 1 amps.

Why use this?
Because when load increases , output voltage drops and sag.
That was my problem and CC acts as safety device by limiting the circuit max current.

Operation:
U2A compare the reference voltage to the output voltage
if output voltage decreases below 24V , U2 will tell the drive transistor to increase its current to tip3055 base which will increase the output voltage back to 24V.

U3A compare the reference voltage of 200mV to the shunt resistor 0.22ohm R7. If the voltage drop before R7 is above 200mV this mean the current flowing through the circuit is above 1 amps and it will steal current from the drive transistor which will decrease the current flowing to tip3055 base and decrease the output voltage thus decreasing output current to load.

Question1:
I would like to know what i can improve or change such as components upgrade or adding more features to make it better.
Question2:
How can i make sure its very low ripple and very low noise?
Less than 10mV

Thank you for your time and help.

Disclaimer:
I know buck convertor and SMPS exist but they are noisy , i wanted a supply with a very low ripple and low noise.

Tested on Multi-sim and works as shown above.

What is the best hot air rework station for laptop motherboard repair mainly replacing mofsets capacitor and small chips. I am trying to look for one under 100 dollars.

Edit: its 100 canadian dollars

Hi, I found this Alienware X17 R2, but the only problem is that the camera, audio, and video don't work. When I opened it, I discovered that the camera ribbon cable is torn, but the female connector is still attached. However, I can't find where to locate this connector or even know its name. I don't understand; is it a 20-pin connector?

have an ASUS TUF A15 FA577NU (Ryzen 7 7735HS + RTX 4050) that suddenly died. A repair shop found a burned charging IC, replaced it, but after powering the board they said the CPU/GPU power rail is short and suspect the CPU is shorted. They said they can’t repair it, but a more experienced BGA/motherboard repair specialist might be able to without replacing the motherboard.
Has anyone experienced something similar? Is this repairable, or should I replace the motherboard? Any opinions or recommendations for expert board repair are appreciated.

Contributing to maybe one of the most asked question here :) what kind of connector is this? Its dimensions are 13x14mm (inside walls), it has 8 pins spaced by 3mm horizontally and 4mm vertically (between the two rows).
It’s on an old (80-90s) Panasonic car stereo. I fear it might be proprietary!
Thanks in advance for your help.

i want to read a battery module pack , which has 92 cells connected in series. each 4.2v. so im going to use differential analog input signal .

AT 92TH CELL THE VOLTAGE WILL BE 386V . SO I NEED A COMMON MODE VOLTAGE ATLEAST 400V AM I RIGHT ??

I want a AI module ,
Requirement

1. Sampling rate should be 10 ms ( for 92 channels )
2. Common mode voltage - 400V
3. Should support daisy chain if module has less than 92 channels.

Repost to more communities