I have to replace these two chips. Never used a hot air gun before. Tried to unsolder from an old scrap motherboard with no luck. Is there any work area prep tricks and tips i should know about before starting? If there is an open area under the board will the heat dissipate too much to prevent the solder from melting? Any tips would be greatly appreciated.

Wondering if this board has an accelerometer. I know nothing about this and this is why I’m asking. Also what is the gold cylinder? Any help is greatly appreciated.

Hello, as the title says I want to measure the average DC positive voltage of an AC drive waveform for a grid of a vacuum tube (I know the flowing average current ~0.522 so i want to calculate my grids dissipation P = U * I)

Frequency: -1.4 - 2 MHz

Amplitude: -Negative peak ~1.5kV, -Positive peak probably? 0.65kV

Signal shape: -shifted Sine Wave, positive peak smaller than - negative peak, Class C oscillator drive signal. - Positive cycle is <180°

For that I have soldered 22 1N41448 diodes in series and used a moving coil DC voltmeter. (0-400V DC)

It measures just a bit over 0V around 20-30V? that is impossible, adding a 1nF capacior across the meter changed it to show 240V DC which makes more sense. If i use a larger capacior the reading changes to be more positive. I have also tried moving iron voltmeters and the readings are slightly different +/-20V or so with having both referenced with a DC source.

Thing is that "filter cap" obviously falsifies the reading since it doesnt measure the average anymore but the near peak of the waveform.

so my question is how could i use an analog voltmeter to measure the average positive grid drive waveform, or how would i compensate for the pulsed DC coming from the rectifier which my analog voltmeter is too slow to respond to?

I cannot use my oscilloscope since my probes cannot take the full amplitude of the circuit and would be damaged, even after the rectifier, it also falsifies the reading by the probes capacitance and i would still need to figure out the average voltage.

I can give more information on request, thank you.

I am testing several different high current pcb connectors from wuerth that I got sent for free. They are rated for 50A, some even >50A but most of them are only connected to one side of the PCB according with no vias/plated vias undearneath. I am curious to see how they will perform!

I've added a small shunt + ina219 circuit to test some high current measurement with a shunt.
I am trying to run up to 50A through this board.
The shunt is rated for 10W with 0.004 ohm, so even at 50A it should not exceed the specs. INA219 as a cheap op amp replacement with very low input offset. I2C to Arduino to measure the current.
I've added all these vias but I am not sure if they are actually helping or increasing the resistance in the end.
I've never worked with a current that high on a PCB before, so any suggestions would be appreciated.
Thanks for your time!

Left picture is the best representation of the setup I'm going to be working with, right is what I see everywhere and wish dearly I had. Description below for the left picture.

I have been given the amazing task of coding in python the communicating from a RPi 4 to a bunch of STM32 by CANBus. The whole thing is already built by some people that are long gone, sweet... Never done that before but eh, I played some factorio so I know what bus is right?

The things that is completely stumping me and my colleges is the way these the whole thing is setup:

-Each STM32 is on his own PCB, so far so good. Each PCB is about 2 inches apart btw.

-The CAN_H and CAN_L Bus is immediately "stopped" at the first PCB, by that I mean it goes into a MCP2551 CAN transceiver with the mention "CAN_IN" on the board. uh???

-Each PCB has its own CAN_IN CAN_OUT, so 2 MCP2551 per PCB. Kind of a cascade instead of a bus?

I will have access to this amazing piece of engineering in about a week, so I am simply wondering what to expect on the side of communication. Are these... relays..? going to affect how I communicate with the 4th STM32? It feels like the nodes are between many small busses? Or should I treat this as a normal CANBus where each node receives the message and only the one with the right CAN_id actually read it?

Forgive the snark, I would be really happy to be proven wrong. Is this left side setup overly complicated like I think it is? Or am I the fool?

Thank you

Hello, I am looking for relay or conductor. That can handle switching DC voltage without disconnect arc and is controled by AC voltage. I was googling for ages and cant find good cheap product. Thank you very much. Sorry for my english, I am not native speaker.

I need a high side switch to output 5V when a 1.8V logic signal is HIGH on its input. I bought the TPS22919 but it's not passing V_IN with 1.8V applied to ON pin. I'm looking at https://www.ti.com/lit/ds/symlink/tps22919.pdf and now wondering if V_IH is dependent on V_IN and if 1.8V is insufficient when supplied with 5V. Should this work, and if not what's the simplest arrangement?

This is to supply a bias voltage for an active GNSS antenna which draws about 20mA, I'm switching the supply to save power between locates.

Hey, I'm looking for a 2200uf, 56v (or above?) Capacitors for a 90's HI-FI amplifier repair but finding these strangely hard to Source. I'm in the UK, but guess to the wonders of international postage I can order from anywhere.

Thanks in advance

I am working on a lightsaber project with an arduino. Im using 2 144led argb strips for the blade that run at a max of 45w and run at 5v. I have an 18650 battery that provides 3.6v so i needed a boost converter to make it 5v. I got this XL6009 which seems to work well and provides me over 3amps which is fine for the brightness and length of the strips I need, but its getting really hot when leds are powered.

I was wondering if this is dangerous in any way or if it will cause issues. This is what I got (https://www.amazon.co.uk/DollaTek-XL6009-3V-32V-5V-35V-400KHz/dp/B07DJ4F1BN).

Thank you.

Hello, I’m extremely new to this. New as in I’ve never built anything. I’m interested in making a voice box for a Phantom of the Paradise cosplay, and I found a tutorial online.

https://www.instructables.com/Phantom-of-the-Paradise-Voicebox/

Would anyone mind helping me find the correct parts listed here? The ones without links, I mean. Also, does anyone have any advice on good tools to start out with?

Thank you so much!

The shown circuit is an LLC resonant converter. It produces an inductive kickback from the primary winding (50mH) and that creates a negative current through the 12V source, seen in the gif. Is this bad for a high current rated LiPo? I plan to install this converter with a 6200mah 120C 3S LiPo battery (bomb) in an aluminum chassis for portable power. I am wondering if i need to install additional components to absorb the kickback, preferably without wasting much power if that is the case. Thanks

I was attempting to open this plastic cover and it was stuck, so I tried to pry it off. Accidentally hit the wire with the pliers while trying to pry and noticed this pink wire frayed. Is this repairable? And if it is, how?

This is a fridge light for my small 12v camper fridge.

Problem is, it stays on when the door is open, no way to turn it off (I need to leave the door open between trips, dry the fridge out, no mold).

I want to add a little inline button, between this 2 pin male/female connection.

I've had a search, there are a load of different types. Does anyone know? And any ideas of best button/switch I could use for this?

Thanks :-)

hey! i have this collectible doll that’s supposed to play music, it stopped working suddenly and when i opened it the speaker got loose. there’s super thin copper wiring with two strings but one of them broke. is there a way to replace it

I have a few of those buttons that will play a recording they use to train dogs. I'm trying to design a mini golf course where the ball will hit the button along the course and play a sound.

The problem is, the golf ball doesn't seem to activate it most of the time, either because it doesn't hit it long enough or with the right pressure. I've tried dropping it from various heights, rolling over it horizontally (like a floor booby trap), and hitting it at an angle at the end of a tube.

The second image shows the button taken apart. The black circle on the board is the actual button, which is pressed by a small protrusion in the center of the yellow button. There is a ring of foam to dampen the press. I've tried with and without the foam and get slightly better results without it

Does anyone have any ideas for how I could improve the success rate? I know this is a weird question. I could link a video if needed. Thanks!

I built this circuit with a 33k resistor and a 100n capacitor and it didn't work. Is it a problem with me or the circuit?

Looking with the oscilloscope it seems that the /OE signal is simply an inverted A15 signal from the DP7801 but what would be the function of everything going into the first gate especially pin 5?

Measurements from my oscilloscope:
Pin 5 is at a constant ~3.8V
PC5 is constantly low.
A14 looks like a normal data signal line. (is also used for the upper half of the ROM's memory)
A15 looks like an inverted data signal line. (not used for the ROM)
Pin 6/10 of the 7420 seems to be constantly high from my measurements. Which is probably due to PC5 being low.

I'm trying to build a reproduction cart for super cassette vision, and would just be able to copy the circuit on the board for the Output enable line but I would also like to understand what it's doing. Especially as this circuit is taken from a 32KB board and there are 128KB games for the system (which uses some of the dataline used in the example for normal data), so knowing how it works might help me make a /OE signal for those games. (I don't have a 128KB game, they're collectors items it seems. The 7801 has 16 bit address bus which it also uses to access the eprom in the cartridge but I suspect the use PC5 as a 17th bit for that to access 128KB)

Ive recently been working on a lot of old tech that likes to do the above mentioned and I want to get a respirator for it but I don't actually know what Id need to filter, and I cant get any concrete answers onlne

Hello.

What I want to do is to ask to a pcb maker to create the BBQ20_USB_Keyboard for me (because it is sold out,but I need this nice keyboard for building my DIY phone)

The BBQ20_USB_Keyboard comes equipped with a blank RP2040 with nothing written to it.

I will need to write firmware to this.

It's not difficult, though. The Raspberry Pi Pico RP2040 uses an excellent and simple method for writing firmware.

When I connect it to your PC via USB while holding down the BOOTSEL button, it will be recognised as a USB memory stick. All I have to do is place this file here.

However, there was a major oversight.

The BBQ20_USB_Keyboard board does not have a BOOTSEL button...

With a regular Raspberry Pi Pico, I simply press this button...

However, with the BBQ20_USB_Keyboard, Il need to connect these two round metal terminals on the back of the board.ZitaoTech doesn't need a button.

ZitaoTech (the original keyboard creator) doesn't need a button so Il need to go through a procedure that may be difficult for me.

I need to use something metal (such as tweezers) to electrically connect the BOOTSEL test metal terminal and the GND terminal while connecting the USB..

Well,I would like to know if I can use some kind of jumper or connector to connect those terminals. It would be easier for me than using a tweezer.

Thanks.

Heya

I would like to build an 8 bit computer but simulate everything in a computer program.

I've found these 2 but I'm not sure how far I would be able to go?

https://www.tinkercad.com/
https://www.falstad.com/circuit/

Would the turing complete game sandbox allow me to do this?

Thanks!

This is an Acer one 8 tablet that I am trying to revive because it's battery died and I got these 4 18650 cells. when I try to turn it on, it shows the boot screen for a second, then immediately turns off and shows low battery icon. What can be wrong with it? It was working fine with the original battery.

The most accurate thermistors that I've ever seen are in the temperature sensitivity of 0.1°C How can DAQs and instrumentation devices can go far beyond that?