Hi all! Does anyone know where I can find Razavi's problem solving strategies for electronic circuits? Thank you!

So I'm planning on building a adjustable map sensor basically it takes the output signal voltage which caps out at 5v and let you control it from 1-6 volts, and normally people use a potentiometer and make adjustments that, what I want to do is use a milli volt amplifier and use the throttle position sensor milli volt out to ramp up the map under load. I just need help knowing what I need to buy and some guidance on how to wire this

This what people use to build one of these Multi-turn (15) Cermet Potentiometer 1000 ohm

LM317T Adjustable Voltage Regulator

220 ohm metal film resistor

Mini Terminal Strip

Heat sink for Regulator

SPDT toggle switch

https://preview.redd.it/2q034utjfzfe1.jpg?width=1598&format=pjpg&auto=webp&s=8f95d03e00e717f4d2072916b8e40e4078c134ac

So, I have a control circuit for a machine which has the standard 120VAC control voltage feeding a full wave bridge rectifier to create a DC voltage used in the rest of the control system. See the red boxed area in the image.

I have never seen a filter cap in series with a resistor, and while I've not done the math, it doesn't and wouldn't provide much smoothing. I've not been able to hook it up to a scope so can't confirm, however, I believe I basically have no smoothing, and only rectification so I wind up with around 175 VDC. except that it is just the nice top half of an AC sine wave.

Why would they do this? Is my assumption about how the circuit will/is working correct?

Hello. I am no electronic expert at all that is why I am asking for help.

I am experimenting with motion sensing to turn on a strip (about 12in) of black light for a project.

I can get the RCWL-0516 to work as it should without any problem. But I need a way for it to turn on the strip of 12v (SMD 5050) led lights. The output of this sensor is 3.3v which is not enough to power the strip. So I did some searches and found that a mofset is probably the best bet to get this to work. With the lack of knowledge and the countless types mofsets I am seeking help. In my mind it works as a relay. The 3.3v signal can trigger it to send the 12v to the lights.

This will be done without an Arduino. Many diagrams I see resistors being used but am not sure if they are needed in my application.

I am seeking help to figure out which Mofset and if needed which resistors that should be used.

It would be nice to be able to use a mofset with pins rather than SMD ones. Though I can get the small boards for SMD if needed.

Thanks!

Im working on a rc car car project and in the control board there is a micro controller (i think) that that has the following code:

RX-2 -6

3F02128G

Can someone help with this?

Thank you verry much :)

So I got an assignment where I had to make an 4 way traffic light seemed very simple initially So I started with basic 1 Arduino UNO 4 light of red , green yellow And 4 resistor And made connection like this attached in img 1-4 are the number for traffic light and if one light is on then rest of rem are off in that light

https://preview.redd.it/qe38zeabxqfe1.png?width=1080&format=png&auto=webp&s=6e12f38fd02928fa4396f738f23a12ace98ee84a

But the problem is it only turning on green and yellow light but not red one

Ps: someone told me that one light cannot be connected to 2 pins .is it true?

Hi, I'm new at electronics. Can someone tell me the meaning of the W in a isolated converter? Example b1212s 1w, does it mean wattage? If it is. Does it mean the converter requires 1watt input to function or it's only capable to produce 1watt output?

I want to see it

I'm unable to find any good information on testing this thing, please help

Hey, lately i've been using voltage divider to shift from 5V to 3.3V (mostly for rx tx pin) and i want to switch to logic level shifter. Which type i need to pick the IC base one or the transistor base one for seitch the tx rx signal?

I would appreciate any help on this to see what kind and where I could buy a flat blue LED light for making a movie ticket with a power source that is feasible to make it glow

As the title suggests, I'm looking to learn and understand the design of more complex circuitry, and would love to have access to schematics that also explain what the different components are doing in a circuit etc.

Does anyone know of any sites that have these?

I've found schematic libraries online, but im really also looking for the explanations.

I'm trying to find a motor driver IC that has digital data inputs to drive a solenoid forward or in reverse, and a digital pin that enables/disables the driver.

The one below has digital inputs for forward and reverse, but there isn't a ping that turns it 'on' or 'off'.

https://wmsc.lcsc.com/wmsc/upload/file/pdf/v2/lcsc/2209221130_Wade-WD6208NSTR-G_C5176025.pdf

Edit: This one seems to be sufficient for my needs. I wonder if there is something cheaper. https://www.lcsc.com/datasheet/lcsc_datasheet_1809212034_Texas-Instruments-DRV8837DSGR_C39159.pdf

This schematic is from a circuit made in this video - https://youtu.be/5vRAACeebjI?si=85AasShj8a6ngaV6

I can understand how connecting the output of one circuit to the input of another in this case turns one LED off and leaves the other on, but I don’t exactly understand how adding a capacitor and 10k resistor causes an oscillation between the two LEDs. I’m really struggling to understand specifically what the 10k resistor is doing in this instance. I’d appreciate any input on this.

https://preview.redd.it/i0wej2ersrde1.png?width=1652&format=png&auto=webp&s=05e21074ec5001ae280912ef42e3a967e3fa9502

Hello r/electronic_circuits!

I’m a complete beginner trying to build a small device that measures tilt (via an MPU6050 accelerometer/gyro) and moves an MG90S servo accordingly, using an ATmega328 as the controller. The device is powered by a single 18650 Li‑Ion battery, and here’s the setup I’ve cobbled together:

1. Li‑Ion Battery & Safety
   • One 18650 cell (unprotected)
   • TP4056 for charging
   • DW01 + FS8205 for battery protection
2. Voltage Regulation
   • 5 V boost converter primarily for the servo
   • 3.3 V linear regulator (LDO) for the ATmega328 and MPU6050
3. Current Schematic’s ON/OFF Method
   • Currently, I have a slide switch at the input to the 5 V boost.
   • When OFF, it just disconnects the boost converter; when ON, the entire board is powered.

What the Board Is Supposed to Do

• Measure the board’s inclination via the MPU6050.
• Use the ATmega328 to calculate how much to move the servo.
• The servo (MG90S) tilts a small mechanical piece based on the orientation.

What I Need Help With

1. Schematic Validity
   • Is this design correct, or am I missing something crucial (pull‑ups, decoupling capacitors, filtering, etc.)?
   • Could it be overkill for such a project? Or do you see a simpler solution to get stable 5 V for the servo and 3.3 V for the MCU and sensor?
2. Single Push‑Button for Full Power Off
   • I’d rather not use a slide switch. I want a momentary push button that toggles power on/off completely.
   • The idea is: Press once → system turns on, press again → system fully shuts off (no power draw, not just putting the microcontroller to sleep).
   • I’ve heard about bistable latching circuits or specialized power-switch ICs. How would I integrate something like that so it physically cuts off power to everything?
3. General Advice for a Newbie
   • Any pitfalls or “gotchas” you see here?
   • Are there recommended component value changes or alternate approaches to keep things simpler and safer?

I’m attaching a PNG of my schematic. I’d be super grateful for any thorough feedback—I’m really unsure if this setup is correct or if there’s a more straightforward way to achieve my goal. Thanks in advance for any help !

Hey,

so im trying to control a KK-0520B solenoid (5V, 600ma, 5mm travel, 0.2-5N) with a RP2040zero pico.

My setup:

https://preview.redd.it/ksec3enllnde1.png?width=519&format=png&auto=webp&s=c420a0d8268ef62d4cbcc23e826262e8417dbfb6

5V is connected to the top left pin, GND to the GND pin.

I can't get the coil to activate though. I did some napkin math and to get the required 600ma I would need a 325ohm resistor (using a gain of 75).

I did that, nothing. Removed the resistor, still nothing.

If I swap the coil/diode combo for an LED I see the circuit working.

I think I'm just not allowing enough current to flow.

I attached a current meter and it didn't measure anything.

Can I get a confirmation on the resistance, the circuit in general, and anything else I'm doing wrong?

If I supply 5V directly to the solenoid it actuates.

I want to solder an aux cable to my old car cd player so that I can connect an external player.

This is a common hack, but my CD player doesn't have the typical markings for LC, RC, GND. So basically I am looking for the signal points between the CD and the board to connect to them my external signal. Can someone make sense of that board and the markings?
I don't know the make and model, but it is for a 2005 Mercury Montego
Very much appreciated!

https://preview.redd.it/hm7fv9f08ode1.jpg?width=4080&format=pjpg&auto=webp&s=f21471b086636aeb6fae0388b3eb517084403c42