AskElectronics

A few months ago I designed a gas sensor board based on the MQ2 gas sensor and wanted it to be portable. I created a custom schematic and PCB and reviewed it before sending it out. I soldered it together and bootloader the board and can successfully upload code to it but there seems to be a voltage drop for the Lithium-ion battery that I'm using and I'm not sure exactly where.

Here is the battery: https://www.digikey.com/en/products/detail/jauch-quartz/LI18650JP1S1P-PCM-2-WIRES-70MM/9560968

And the review request (though some changes were made) : https://www.reddit.com/r/PrintedCircuitBoard/comments/1b3wilu/pcb_design_review_request_mq2_gas_sensor/

Here is the schematic section about this part of the board:

Charging IC

Protection IC

Boost converter

Power section

Protection IC

Boost IC

Overview of all 3 sections

I know I used the same BAT global label at 3 different locations: One at the battery charging IC, one at the voltage divider of the protection IC for the lithium-ion cell, and one at the boost converter input.

I cut the trace that connected the divided voltage from the 2 1k resistors and installed an external jumper for that and the input of the charging IC. However, I still see a voltage drop when measuring concerning ground (although I don't see one when I'm measuring concerning BAT - presumably because it technically isn't GND at that solder pad).

Right now I have my power supply connected to BAT + and BAT - with a voltage setting of 5.34V and at JP32 I measured a voltage of 4.54V, and at the output of the boost converter I see 3.33V (When a USB is plugged in there's no voltage drop and it outputs 5V).

I also tried replacing the protection IC because the first time I soldered it the chip was crooked, so when removing it pin 3 (CO) peeled off a bit and the power supply was no longer providing power to the gas sensor or rest of the board. I reconnected the trace and power came back on the board, so I wonder if the IC is causing a drop.

I'm wondering where to go from here because I thought originally it was the resistor divider but now seeing the problem is persisting I believe it has something to do with the protection IC.

I'm designing a board with the W3011, a compact GPS chip antenna.

I want to mount it on the edge of my board, but I'm curious why the keep out space is extended "into" the board? IE, why I can't just rotate the chip 180 degrees so the keep out space is "off" the board.

I understand it might affect theoretical performance but I have no RF knowledge and would appreciate if anyone has insight. Thanks!

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I've been messing around with some hall effect sensors lately. I have a Unipolar Hall effect sensor in a simple led circuit with a battery. When the south side of a magnet is close to the sensor, the LED activates.

My question: is there a way to do the inverse/opposite? Where the LED is on but deactivates when the sensor detects the magnet.

Hello guys.

I've been wanting to buy a microscope for SMD soldering for a while now and I need some advice. With a budget of 100 euros/dollars, I'm between two options:

• Eakins microscope camera (the light blue one): https://es.aliexpress.com/item/32803731419.html?spm=a2g0o.detail.0.0.28c7c5PHc5PHQr&mp=1&gatewayAdapt=glo2esp
• Andonstar AD246SM (with some discount coupons I can buy it for 100 dollars): https://es.aliexpress.com/item/1005006811951827.html?spm=a2g0o.detail.0.0.28c7c5PHc5PHQr&mp=1&gatewayAdapt=glo2esp

Which option is the best? Can you recommend me other options for my budget? I will be using it for console repairing.

Thank you so much in advance!

Does anyone know why this happened? I live in an apartment with a dimmer switch. Maintenance came by about a month ago because a part of the dimmer switch was stuck and breaking. They fixed the part, but I'm not sure of the specific steps they took to fix it. Anyway, about a month later, I had left the dimmer at its lowest setting. When I came back home an hour or more later, one of the three bulbs connected to the kitchen island fixture had gone out. But when I turned the dimmer back up to full power, the light came back on. Also, as a side note, I've been hearing an electrical buzzing sound occasionally coming from either the lights or the dimmer. It usually lasts a few minutes and comes and goes.

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I cannot figure out how capacitors work, assuming the voltage fluctuates from the battery would this circuit prevent that before going to the system load? Why did i have to add the resistor, the simulation didn't show voltage on top until I did, Is that the software or an accurate simulation? When trying to smooth the voltage what size capacitor do I need?

Greetings

Im an Eletronics student, and I was tasked with building an amplifier with specific componets, which happens to forbid me to use capacitos to filter DC into the amplifier and easily bias a npn transistor.

To remedy this I used a Diferencial Pair design. But I am still curious if there are any other options of designing the input to correctly bias the transistors without the use of capacitor:

Final note: This is actually for an evaluation, but Im not gonna ask for you to solve it for me. I just wanna know what other amplifiers ( voltage gain) could be build with 3 npn transitors and 5 Resistors that solves the Input bias without a capacitor or a Differencial Pair design, cuz i have no other clue

The design I used( no resistor values for Privacy concerns)

Thanks for reading and have a nice day ( :

I'm working on some furniture, and I would really like to add some USB charging to to the piece.
I'm having a hard time locating a part. I basically don't know what these are called.

A name and a link would be so helpful!

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Thanks!

Hello everyone,

I'll post the actual question first:
Can I produce two simultaneous and synchronized 40hz signals using this signal generator?
https://www.amazon.de/-/en/gp/product/B09CGXT6CX/ref=ox_sc_act_title_2?smid=A3SCFTIO8CSK1X&psc=1

The signals should follow the ones depicted in the image I linked below. I assume I can, but I want to be sure.

Now, as to why I need to do that:

I'm very new to electronics and I'm trying to slap together a setup that could produce a 40hz light flicker and 40hz sound clicks, synchronously at the rising edge of the signal. The device is meant for a parent suffering from Alzheimer's.

Right now the plan is to build the setup using a cheap signal generator from Amazon that would control a MOSFET module and the MOSFET module would in turn control a LED strip. A separate power supply would power the LED strip via the MOSFET module.

The sound signal from signal generator's other output would presumably be inputted to a sound amplifier and headphones plugged into that.

From the research article about 40hz light and sound's benefits in Alzheimer, I deduced, that the light and sounds pulses were synchronous so I can't use a online tone generator, for example. Here's a picture from research article, depicting the light and sound signal:

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If this pulse generator works so that I can get two 40hz signals out of it and adjust the duty cycle to produce the signals seen abobe, I'm good.

MOSFET module: https://www.amazon.de/-/en/gp/product/B0CBK7D1GD/ref=ox_sc_act_title_9?smid=A3SAUZ08XSJQZG&psc=1

Signal generator: https://www.amazon.de/-/en/gp/product/B09CGXT6CX/ref=ox_sc_act_title_2?smid=A3SCFTIO8CSK1X&psc=1

The research article I mentioned: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0278412

Thank you in advance!

I'm having trouble programming an STM32F042K6T6 microcontroller on an exixe12 board for a nixie tube project. Every time I try to connect the board with the microcontroller to STM32 ST-LINK Utility (and STM32CubeProgrammer) via an ST-Link V2 (Chinese clone. I've tried two with no success). It pops up with the error "STM32 ST-LINK Utility Error (Can not connect to target!)." I've checked continuity, voltages, components, and pinout on the board and on the ST-link V2. Everything seems normal according to the documentation I've looked through. My computer does detect the ST-Link V2, but not the microcontroller on the board.

I am pretty new to this stuff, so there's a good chance there's some small detail I'm overlooking, but I've scoured all the forums I could find on the subject and none of the solutions seem to work for my situation.

I have posted an issue to the Exixe github page, but it looks like it's pretty deserted over there, so I don't think I'll be getting a response any time soon.

If anyone has any guidance on the issue, I would absolutely love it.

Also, let me know if there's any other information I can provide that may help. I've looked through A LOT of documents in the past week, but I'm not quite sure which are relevant to solving this issue.

Edit SOLVED: credit to u/_greg_m_ The wires that came with my ST-LINK V2 clone were too long at 18cm. I cut them down to 10cm each and easily connected the STM32F042K6T6 microcontroller with STM32 ST-LINK Utility.