It is a 4 digit digital lock system, and ive been on youtube but i cant seem to find anyone that teaches how to add a reset button, pls help this poor student🙏

Hey everyone, I could use some advice on identifying a missing component on my laptop's display model (SHARP LQ156M1JW09, 1080p 240Hz). I recently took it to a repair shop, and it looks like they removed a component from the display circuitry, but they're now denying it. From the surrounding parts, it seems like the missing piece might be a ceramic capacitor, but I’m not entirely sure. Has anyone encountered something similar or could help confirm if it’s indeed a capacitor? Any input would be appreciated!

https://preview.redd.it/rz3grr9cjvzd1.jpg?width=4000&format=pjpg&auto=webp&s=29cce21b9e774a3849f9b984c340e195f496881d

Help. Ive tried so many times. Cant get it to work. Just want a button that activates a few leds and a small motor. It then thrns its self off after 5 seconds. Ive tried timer 555 couldnt get it to work. And all sorts. Help

From the book \"Practical Electronics for inventors\" page 936.

I prototyped the design on a breadboard and it works. I use the enable pin as speed control by applying a PWM signal.

I was told by a colleague about an issue with the source of the low N-channel MOSFETs when Q5 is off, since the ground is cut off, the voltage at the source pins will float high and might cause problems for the low side MOSFETs (either conducting slightly or negative Vgs).

I wanted to confirm if this is a problem, and if there are other solutions to apply PWM without needing Q5 MOSFET, thanks a lot.
Also, if anyone can suggest some good resources that have well-designed circuit diagrams I would be very grateful. Cheers!

Hello everyone, I need help in connecting my LDR to my circuit. I have 2 motors connected in parallel and 2 batteries connected in parallel in the circuit. May I know how should I connect my LDR in my circuit so it can cut the circuit so my motors won’t move when there’s no light source?

Hi,

Despite my EE education, I'm unsure what is the role of the current mirrors in the schematic - https://github.com/littlebitselectronics/eagle-files/blob/master/INPUT/LB_BIT_i13_LIGHTSENSOR/LB_BIT_i13_LIGHTSENSOR-v03(5_5)/LB_BIT_i13_LIGHTSENSOR-v03(5_5).pdf

https://preview.redd.it/04b5tjbov2zd1.png?width=874&format=png&auto=webp&s=449b92b49142a025acc820330f09ae226df38926

- The Op amp U1 on the left has gain = 1 and practically turning the current mirror from R4, Q1A, R3 on and off based on the Op amp input. In case of SM1.SIG = 0 V I can say the Op amp output (pin 4) is at 0V, hence current mirror is on, but the Q2 is closed.

So where the mirrored current from Q1B is flowing, when path to the Q1 and Q2A is closed? There is no other path to the ground.

- The Op amp U2 is in the role amplifier with gain around +/-10.

- The switch SW1 is switching between inv. / non. inv. amplifier of the Op amp behind.

- The current mirror from Q5A and Q5B has low output impedance given by the R12. Analogically for the mirror Q3B and Q3A.

My question is why I would waste transistors when the Op amp has hypothetically infinite input impedance and does not need low impedance (high current) on the input?

Thanks for your two cents.

Would like to try and repair some LED lights and am trying to source this film capacitor.

I replaced a ceramic capacitor, and electrolytic capacitor, a diode and a 15 ohm resistor with a 10 ohm and a 5 ohm in series. What do you think and what should i improve in soldering and that

Hi, i am trying to do a project that i can control a servo with an IR remote but without a microcontroller, any ideas ?

The strike-through text would not be a possible scenario as inputs 2 and 3 will never be active at the same time.

https://preview.redd.it/fzsj75tp68yd1.png?width=663&format=png&auto=webp&s=a315281c5648de21a86ff51f28d36c0f101e49dd

This is a chromebook usb c charging port. Upon checking there are no "spare" parts available for diy replacement. Usb wont charge, sometimes it will find an angle where it does but it very rare so I'm checking if this one is repairable.

I recently graduated with my BS and MS in Biomedical Engineering. At first my job post grad, I found my knowledge of ACTUAL circuits to be severely lacking. In school I learned basic circuit analysis, RLC circuits, OpAmps (mostly LM741), and SOME signals/systems (e.g., Bode plots, transfer functions).

Despite my education, when I look at an ACTUAL circuit board, I have zero idea what's going on. I know the basic ideas of diodes, transistors, transformers, etc. but have never used them or done any circuit analysis with them. I look at all the little black chips on the circuit board and have no idea what they heck they're for.

All this being said, I'm a firm believer that it is within my reach to understand all this if pointed in the right direction. Where would I go to continue my circuits education?

Bought a light recently for one of my aquariums and has 3 lights modes, I want the one with most of the white LEDs and some of blues and reds.

When I turn off the setting resets and I have to manually set it up.

It's a cheap ligh and not a smart one, so I don't mind changing something.

Can I remove the controller and wire it directly to a power supply or do I need to do something else?

Or if I cut the brow wire will the light still work but not the controller?

thanks in advance

Reverse Polarity (left), Over voltage (mid), current limiting (right)

Hi community, I need some help on this protection circuit.

Before implementing circuit protection, my R4 is 41.67ohm. 12V directly is supplied and i measured 310mA input current. I need to maintain voltage close to 12V.

Which in this case, i use LTspice to simulate when i integrate protection circuit, Vout is 11.86V, still acceptable. To check input current, i placed a 1ohm resistor after the 12V supply, i draw like 266mA, which i personally feel its may not be acceptable. I am not sure how to do the circuit limiting/overcurrent protection part. Especially when R4 is 1ohm to simulate short, its 772mA, too much.

I was wondering if there is any way i could cap the input current to 350mA on normal operation or when overcurrent situation.

Please help me~

Hello people,

I was decapping some ic's and I saw this ivm chip i know it's from a ring token card but nothing more but I want to really see the chip architecture and I I'm wondering how to dissolve the top layer with out damaging the silicon underneath so I thought I reach out here

This is the chip in question

https://imgur.com/a/kubuhpj

I have attached a photo above of where the component was but I’m struggling to figure out what it was. For context I have an electric skateboard and the battery stopped working. I tore the battery pack apart and discovered the circuit component under silicone melted. It appeared they used the silicone to hold the soldered wires on but it then caused the component to over heat. In doing so it’s hard to read the cap that was on it. From what I was able to read it had either a 2 or z above a string of numbers. The string then read 10_12 The _ could possibly be 0,3, or j but it’s very hard to read. The component has the positive of the battery pack o none side then separates into 2 pins one on the left to the output positive and one on the right to the charging positive. Any help identifying it would be very much appreciated.

Hello...

So I'm going to make a project which requires 220V AC to drive a blue LED (that is usually around 3.2V). What i need is the most efficient yet cheap circuit to fulfil this approach. is it the first or the second one better?

https://preview.redd.it/2df86ll6txwd1.png?width=880&format=png&auto=webp&s=a29e21538c320207fa2efd229197a11f75cc2192

https://preview.redd.it/p5spc1p9txwd1.png?width=600&format=png&auto=webp&s=f166f3ae2019273e6c493b55576de763277c1aa0

I accidently cut the FFC on the Mitsubishi outlander stereo and desperate need to find one. Can someone help me locate one? Thank you in advance.

https://preview.redd.it/sumlu3ejyswd1.jpg?width=3000&format=pjpg&auto=webp&s=2ddec804e33fe84c111a9ddaebb2bf0c7d98a4bb

https://preview.redd.it/u4h9xv2kyswd1.png?width=720&format=png&auto=webp&s=692978e475748230bda5dcf8ce991bd742bd4c50

Hi, I am a enginering student and my team and I are building an induction charger, with a DC powersupply. I think we need a full wave cycle for it to have the best results. Our teacher wants us to use a CMOS 555 for generating the wave, put it only outputs posive. Is there a way to make it negative? I tried looking on internet, but most people using 555 only need the positive.

After that, to amplify the signal, we are using a H bridge with mosfets. Would a push pull circuit ve more efficient?

Thank you, and sorry for my english, it is my second language.