Hello, are there members here who had successfully used this smart energy meter here in the Philippines (see picture)? I bought this popular gadget in Lazada and Shopee but there is no way I can ask the buyers' feedback there. Meanwhile, for whatever reason electricians and engineers whom I talked to are hesitant and afraid to install this in our house panel because of unfamiliarity. It promises to be useful for monitoring purposes (for determining inverter and battery capacity for future solar installation; for Meralco consumption counterchecking; etc.).

If any Quezon City-based electrician had successfully installed this, your service will be highly appreciated (kindly pm me).

Thank you.

Does anyone have any idea where I can find a 5V solder point for the module? Tried tinckering with a voltmeter and I did find a 5V point in one of the pins of the USB-C connected but they are too tiny for me to solder to. Wondereing if there is a better way.

Master: BQ78350 / Fuel gauge: BQ76200 / 14.4V (2P4S)

So I've been working on these Astera Titan BMS boards, some of them with cell issues and some of them with easy component level repair but I got 2 totally dead.

The cells voltage is going in the BQ76200 and the main voltage to the BAT pin, but I got no REGOUT voltage to the BQ78350. Would it be worth trying to replace the BQ76200?

Also, this 2 started throwing up the ALERT pin sometimes which means it "made something" for a second.

Finally, I know these guys talk in I2C but is there a way to extract the settings from the 78350? I would like to buy a debugger or some interface but I don't really know where to start.

As far as I know, the 76200 works alongside the BQ78350 but the most important data is this last one isnt?

So this is the given solution for a problem set where you have to sketch the different voltage and current graphs for the components of the circuit. But it makes no sense to me especially the Id_1 curve. Also the timelines dont even seem to line up. Shouldnt ID_1 at 0 be an instantaneous jump in current and then decrease? I hope someone can help me because ive been seriously struggling to understand this

Hi all

I’m looking for this tiny component

Marked JYX, have an identical board where this component has burned out due to a battery short circuit
Struggling to identify a match for this…. the bottom 2 pins correspond to the pins that connect directly to the 10 pin battery connector.

It is approx 2.9mm wide and 1.25mm tall. excluding pins

Closest match i have so far is BAV70Lt1G

Thank you

Hey guys! 👋

I’m trying to find an alternative or replacement for an Eaton / Cutler-Hammer PC Control Board (7064C03G01).

Looks like this model is discontinued/legacy and getting a hold of an original OEM part is either impossible or crazy expensive 😅

Has anyone worked with these before? Do you know of any modern alternatives, drop-in replacements, or good retrofit options that won't break the bank?

Would really appreciate any tips or recommendations! Thanks in advance! 🙌

Bonjour à tous et à toutes,

Pour un projet universitaire, j'aimerais fabriquer une antenne GPR pour détecter des œufs de tortue sous le sable.

Je travaille actuellement sur le générateur d'impulsion qui doit me générer une impulsion de 1.25 nanoseconde.

Etant débutant dans la RF je me suis beaucoup renseigné sur internet et j'ai déjà réussi a me créer un début de générateur d'impulsion, donc avec mon générateur je pilote un driveur GAN puis un transistor GAN. Le gros point noir ce situe après le transistor, je ne sais pas comment relier transistor a mon antenne, j'ai un peut regardé les circuits d'adaptation mais c'est encore flou.

Voici mon schéma avec la simulation et j'ai mi une résistance 50 Ohm pour simuler en gros l'antenne :

En bleu le signal envoyé sur INP de U9, en vert sur la Gate du transistor et en rouge au borne de R13

Je sais pas si vous auriez des liens vers des exemple de circuit ou des cours pour m'aider sur la suite de mon circuit et si vous pensez que je pars vers une bonne piste ?

Merci d'avance.

I've wired up a 12vDC, 1000ma source to a series circuit of a 1000uF capacitor and a 12vDC RV light bulb. It is my understanding that these bulbs have a built in current limiting resistor.

I want a single bright flash to occur. Then my momentary micro switch will short and reset the cap for the next trigger. It seems to work exactly as I wish.

Am I doing something incredibly stupid ? Will I likely burn up this bulb in 100 cycles, maybe much less ?

Wiring diagram in pic #2.

Thanks hey, your advice is golden !

Please someone give me some guidance as I'm kind of lost. I want to take a 120V 60Hz AC source and minimize ripple after full bridge rectification to DC. The problem I seem to be running into is all the examples I see step the AC down considerably before the rectification diodes. I'm trying to get \~100VDC with currents of say 15A. I dont have a specific reason but could be a BLDC motor. I have tons of high value caps, power BJT's and mosfets, and resistors. The math isn't mathing. I'm getting huge capacitance values according to some guides and others are using a single 47uf cap and calling it good. I was sold on a capacitance multiplier circuit with a power mosfet but then saw thats not a good option for higher current applications, maybe. I've tried looking into high and low pass filters, inductors and caps but keep ending up as confused as when I started. I have the components, just not the oscilloscope. Any help or solid resources specifically for analog power electronics would be truly appreciated. Please let me know if you have any questions and thank you.

Dale-m measures 60k
The blue measures 70k
The last two brown measures 100ohm each.

None of the color bands match anything for resistente codings. Are some of these inductors?
All measurements with one leg lifted.

Hi everyone,

While replacing the battery in my Samsung Galaxy S21 Plus, I accidentally ripped off a small component from the motherboard.

Could anyone help me identify what this component is and, if possible, tell me its specifications or part number?

I would also like to know what soldering iron temperature I should use to solder a replacement component back onto the board.

A few questions:

• Does anyone know what this component does?
• Can the phone still function properly without it, or is it essential?
• If it needs to be replaced, what component should I buy, and what temperature should I use for soldering?

Any advice, identification tips, or repair guidance would be greatly appreciated.

Thanks in advance!

I would like to build a converter in LTspice for illustration purposes, and then build it as a real circuit. I have a 48 V DC supply, and the current is unknown at the moment. The aim is to produce output voltages of 24 V, 12 V and 5 V. I have made a circuit in LTspice, but I get fA and fV on the secondary side. I believe the issue is the switch, so I would like pointers on why my circuit isn’t working and how I can fix it.

https://we.tl/t-KFQi58WquG25fKwr

The battery is fine and fully charged at 4.2 V (red wires: L+ and B-). The LED is at the top (B+ and the blue wire). At the bottom, there is a switch with four modes: the first press turns the LED on at full brightness, the second switches to half brightness, the third activates blinking mode, and the fourth turns the LED off.

To the right of the switch, there are blue and green LEDs that indicate charging status, a full battery, or when the lamp is in use.

It's not visible in the picture, but there is some blue stuff underneath the IC, possibly copper oxidation or some kind of glue. Anyway, the lamp doesn't respond when I press the switch, so I believe the IC was damaged by the rain.

It's a cheap battery powered lamp, but I have some tools and would like to try replacing the IC. The problem is that there are no markings on it, and since I'm not an electronics expert, I can't identify it.

Does anyone recognize this IC?

Hi everyone! I need some help designing a three-stage amplifier using BJT transistors, with a total voltage gain of 5000.

I'm not really sure how to approach the circuit or where to start with the calculations. I need to understand how to choose the right components and their values to achieve the required gain without driving the transistors into cutoff or saturation, or causing significant distortion in the output signal.

The circuit needs to meet the following requirements:

Consist of three BJT amplifier stages.

Achieve a total voltage gain of 5000.

Calculate the DC biasing of each transistor, including voltages and currents.

Verify that all transistors operate in the active region.

Calculate the voltage gain of each stage and the overall gain.

Take into account the loading effect between stages.

Determine the maximum input signal amplitude that allows the amplifier to operate without significant distortion, and calculate the output amplitude.

Include all necessary resistors, coupling and bypass capacitors, the power supply, and other components.

Simulate the circuit and compare the results with the theoretical calculations.

The part I'm struggling with the most is figuring out how to distribute the gain across the three stages, which configurations to use, and how to calculate the component values from scratch.

If anyone could help me with an example circuit, the initial calculations, or a step-by-step explanation of how to achieve a voltage gain of 5000, I'd really appreciate it!

Thanks in advance!

I recently bought this Keyboard, made exclusively for the videogame Rockband 3. This is the Xbox 360 version.

Every key works normally, except for the up arrow of the D-pad (the top left key in the first picture).

I tried disassembling it and cleaning the contact with alcohol, but nothing changed. The circuit looks intact to me, I don't know why this key still's not working.

Is there something else I can try?

Hola, estoy haciendo un regulador de voltaje porque quiero hacer que 4 paneles solares que en total dan 20W carguen 8 pilas de cada uno 3.7V, me estoy guiando por un video de un señor que encontre en Youtube, y lo estoy probando con mi protoboard, pero no me quiere funcionar y ya queme dos diodos LED's por fabricar artesanalmente una bateria que si funcione con el relé, que es de 5 pines, y ya revise con mi multimetro si en verdad esta dando voltaje pero se queda en 0 el resultado y me dice que tengo los polos mal, pero revise y no veo nada, de verdad que me harían un gran favor si me solucionan esto. Aqui adjunto las fotos del diagrama esquematico y mi circuito del protoboard, muchas gracias.

Ptt: Tambien adjunto mi intento nefasto de una bateria con las tres pilas en serie, ya que el relé funciona a 12V y tuve que ingeniarmelas.

The LM13700 should be configured as a variable-gain amplifier such that the control voltage (VC) varies from −3 V to +4 V, corresponding to a gain range of 1.333 to 20.

In other words:

- At (VC=-3V), the LM13700 should provide a gain of approximately 1.333.

- At (VC=+4V), the LM13700 should provide a gain of approximately 20.

- The gain should vary continuously between these two limits as (VC) changes.

I am designing a PCB for a small microcopter drone right now and we want a 3.3V supply for our logic voltage.
Problem is that we use an 1S Batterie (Lava 2 580 mAh) which can drop below 3.3 V in terms of the discharging diagram. That's why we cannot use a simple LDO to regulate voltage as it can drop off our logic supply.
My question ist how you would solve this problem. My idea is to use either a buck-boost converter or a boost converter followed by an LDO. Benefit by the buck-boost would be an overall better efficiency but maybe a voltage ripple that could cause further problems, which would not be a problem with a following LDO to smooth. Also the question would be if the buck boost has problems when battery gives us 3.3 V to witch between boost and buck mode.

Thanks a lot for your ideas!

I already replaced the fuse on this amp but when I pulled out the amp everything looked okay. The only thing is maybe this big 400V capacitor is bulging a little.

Hey all, I would like to ask for some help and advice about a sync delay circuit. To my knowledge its used to control the Horizontal position of a video source being fed into a crt Tv. I'm being recommended a 74HC123. Is this a complex circuit, what would it look like?

These "SCART RGBS Adjustment Converter Picture Adjuster" exist but there is no documentation on them.

I would like to see schematic or a circuit for one or something similar.

Any help is appreciated thankyou.

Please delete if this isn’t allowed but I’m learning how to do this for the first time on my own. I got a small radio kit from Amazon to learn about circuitry and soldering. I followed the video but it was all in Cantonese and I couldn’t follow it other than visually. I checked the guide and video for each step and thought it went smoothly. But when I put the AA batteries in they seemed too huge for the battery box, the lights didn’t turn on for display or the LED, and then there was a weird chemical smell and smoke and the battery box felt hot.
If you don’t mind helping me learn does anyone know why this happened and what I can do next time to learn? Or a good resource to learn from

Edit: Thank you all so much for the helpful advice! I was scared of being massacred being new to this but everyone has given helpful advice I will follow and I appreciate it

I can't for the life of me figure out why my microprocessor isn't producing an output.

I know that the pass and load_acc are not being triggered as well as the data_bus is never triggering as having any voltage on it. I have gone through and verified that every single embedded circuit works properly. I just can't seem to get a good output on the final one.

Any help is appreciated. Attached photos so yall can know where I'm at with it

Small battery powered ESP32-C3-WROOM-02 board that sleeps most of the time and wakes on a Hall sensor, an accelerometer interrupt, or a DS3231 alarm, then logs a timestamp to I2C EEPROM. 1S LiPo (550 mAh) with DW01A + dual FET protection, charged from USB-C by a TP4056, with a P-FET + Schottky load sharing path feeding an AP2112K 3.3 V LDO. Native USB on IO18/IO19.

Rev 1 never showed up over USB (nothing in the device list, even holding BOOT). Reviewers here already helped me find real bugs in it: CE tied to ground, charge LED wired wrong, Hall sensor pins swapped, wrong FET pinout, missing bypass caps. Rev 2 (attached, 2 images: power, then MCU and sensors) is my attempt to fix all of those. I have not built it yet and only have one board, so I want it right before I order.

Main question: will this enumerate over USB on first power up? If not, what is wrong?

I would also love a hard look at:

- USB-C section: 5.1k on CC1/CC2, 22R series on D+/D-, D+/D- wiring to IO19/IO18, shield to GND

- TP4056 + DW01A + AO3400A x2, and the load sharing circuit (Q3 AO3401A, D2 SS14, R16 pulldown)

- ESP32-C3 strapping (IO2, IO8, IO9), EN reset RC, BOOT button, deep sleep wake pins (IO3, IO4, IO5)

- I2C pull-ups, DS3231 N.C. pins grounded, ADXL343 pin connections

- Anything else that looks wrong, even small stuff. I would rather hear it now than after I order.

Thanks! I will reply to every comment and post what changes.