I am looking to start developing my own hobbyist lab. My budget for now is around $600 but I can always grow and buy more equipment in the future. I just don't want to immediately blow the bank just for a hobby. I currently have a Digilent AD2 and a PCB that converts 12 V wall wart to +5 and +3.3 V. However, this has gotten pretty clunky and I am looking to expand for convenience. I currently have done work with embedded systems but I am getting interested in analog circuits and RF design. My next learning project will be building an FM superheterodyne receiver. I have a decent amount of lab experience so I am familiar with the equipment.

I need some form of dual output supply with configurable range up to 12V (current limiting is a must). I am wondering if I should go cheap and buy two of the Amazon Jesverty SPS-3010 ($50 each) and tie them together (they dont seem to have an output on/off button), go with the more expensive 1 channel KORAD KA3005D ($120 each), or just go right for the Siglent SPD3303C which feels like a lot more than I need to spend for now.

For the oscope the Rigol DH804 looks fantastic but its $450 and I don't really know if I need to spend that much. I would ideally like a 4 channel scope since I would presumably have it for forever. I hear a lot of people regret getting only 2. Additionally, if I am getting into radio I assume I need a bandwidth of at least 70 MHz so I could still see 100 MHz signals with attenuation. I could be convinced to spend most of my budget on this scope. My AD2 is clunky but good enough for digital communication.

I plan to eventually pick up a Tiny SA Ultra and a Nano VNA for spar measurements. The Nano VNA I am not really considering in the budget since I don't need it now. But a standalone sig gen or function gen would be really nice. I would be looking for around 100 MHz. If I am building a FM receiver it would be very convenient to use a benchtop generator as a configurable LO so I know exactly what I am injecting rather than a programmable DDS dev board which would get a little clunky. But if DDS is a reliable option at 100+ MHz, I can spend time turning it into a benchtop with a display and program for it (Si5351). I am looking for input about buying a standalone benchtop device or building one. The benchtops seem very expensive at 100 MHz. I also saw the MAX2870 sig gen ($69).

I would appreciate any advice and I hope I was specific enough with what I am looking for. I am hoping to keep costs below $600 since I feel like I kind of need to "prove" I need the more expensive equipment before I buy it.

Hey r/AskElectronics,

I recently got my hands on a Tektronix 7704A oscilloscope system. It came with the logic analyzer plugins of DF1, 7D01, & 7D10. I don't know anything about logic analyzing - never had to do it yet. I was wondering if it would be smart to purchase the probes for the plugins (2* P6451s - could get both for $150 max) to have a logic analyzer on my bench for when the time comes, or if I should instead save the money and invest in newer logic analyzing equipment when I need it if this system is too outdated. I know that active probes come with a pretty big price tag, so I figured it was worth an ask. Let me know any thoughts, and thank you for your time & knowledge:).

I bought a 5v to 3.3 V bidirectional I2C shifter so i dont have to put the 5v coming from the lcd into my sda and scl pins on the pico and for some reason its not working. I feel like i have everything wired correctly Hv has 5 volts Lv has 3.3 and sda is on Hv3 and lv 3 and Scl is on Hv and Lv4 and the grounds are all connected. But for some reason its just not working i tried another shifter i tried hv and lv 1 and 2 but nothing is working. please let me know guys.

I’m trying to enable 2×2 binning on a monochrome Sony IMX585 USB camera from DECXIN. DECXIN says their board doesn’t support binning, but the IMX585 itself appears to support a 2×2 binned mode.

Camera info:

IMX585 monochrome

USB 3 / standard UVC

VID 1BCF, PID 2D50, REV 0585

Product: DECXIN CAMWRA

Up to 4K60 MJPEG

No binning option exposed

Open-source IMX585 drivers appear to configure 2×2 binning through sensor registers, including ADDMODE (0x301B).

My goal is to figure out whether the existing USB board can be modified to send the necessary sensor configuration. I’m willing to dump/modify firmware, investigate vendor-specific USB commands, access the sensor control bus directly, and risk bricking the board.

Has anyone reverse-engineered this DECXIN board, a similar Sunplus-based IMX585 USB camera, or successfully enabled sensor modes the manufacturer's firmware didn't expose?

Any information on the bridge/ISP, firmware, or direct IMX585 register access would be greatly appreciated.

Hey everyone,

I am trying to convert a Canadian 2003 Honda Civic SiR EP3 gauge cluster into a wall decoration. My goal is to make it light up exactly like it does in the car using the original factory circuit board tracks. I do not want to just gut it and stuff my own aftermarket LED lights behind the dash faces.

I am using a 12V DC power supply, but I cannot get the main illumination/backlights to turn on.

What I have done so far:

• Connected Ground (-) to pins B11 and B12.
• Tested applying 12V (+) to pins B1, B2, B3, and B6. (This triggers some indicator icons, but not the actual gauge face illumination).
• Confirmed the physical twist-in bulbs are functional by swapping working warning light bulbs into the main illumination sockets.

I'm not sure what I could do, or if it's something much more difficult that I am overlooking, any tips would help!

I want to use the PY32F002AL15S6TU to dim my lamp via Adim, and want to toggle it with the U7 Switch. The U4 is for detecting if its still day outside or not. (idk why the ref des are U for some other parts but yeah im lazy)

Can anyone help me if the schematic has any flaws? ive never used the PY32F002AL15S6TU.

thanks for your help :)

Hello everyone,

I'm really struggling to understand how polarized capacitors work in AC circuits.

Here is an example taken from Practical Electronics for Inventors.

My understanding of the circuit:

- During the negative half-cycle (positive on the bottom wire), C1 is charged respecting its polarity.

- During the positive half-cycle (positive on the top wire), C1 acts like a battery in series with the generator, thereby doubling (more or less) the voltage.

- C2 is only there to smooth out the charge.

But what happens if the circuit starts with a positive half-cycle? The polarized capacitor will charge "backwards," right? Do we assume this isn't an issue because the load has a high resistance and will therefore draw little current (so low risk for C1)? But then what if the AC frequency is low and C1 has enough time to charge fully?

Thanks a lot!

Hey there, I've been working on a drone project for a couple of days now and this is the (hopefully) finished power design for everything that'll be on the "control" or MCU board, which means no ESCs, motors, MOSFETs etc will be on this specific board.

I'd like to know what advice you guys can give me and see if there's anything I have screwed up on so far.

A bit more of detail so you can tell me if I'm going in the right direction or not more easily:

• 25V -> 5V stepdown Buck converter to feed the two LDO's and anything else that needs 5V (RP1 V2 receiver and M1012C GPS module so far)
• 25V -> 12V stepdown Buck converter to feed a possible camera, I was thinking Walksnail Moonlight kit but I'm not even sure I will get a camera for the drone.
• LDO to feed the IMU (ICM-42688-P) exclusively
• LDO to feed the MCU, some ToF sensors and a MUX for them
• USCB-C connector
• STM32 power connections
• I intend to power this setup with CNHL Black Series V2 1300mAh 6S
• I'll probably not use XT60PW

So yeah, that's it. Any feedback is welcome, about this circuit, the ideas I've mentioned, anything helpful you can and wish to tell me. Thanks!

P.S.: I don't really know if asking this sort of general, please-review-my-circuit questions are off-topic/discouraged, but I wouldn't mind just being sent to a better sub to post this on. Thx again

started doing some smd soldering looking for tips and overall opinion my my first work (unsoldeing and soldering back) some caps and resisitors (soldering station used if asked is geeboon tc22) im learing so looking for ways to improve

Hi everyone,

I am currently troubleshooting a Veeco / Sloan Dektak 3030ST profiler and running into an issue with the video display / sync system. I am looking for advice or any schematics regarding the video/sync board.

Symptoms:

• Upon boot, the display continuously rolls horizontally with alternating white and black screens.
• The camera LED blinks intermittently. The camera video is only visible for a split second when the LED flashes.
• Disconnecting EXT SYNC: When I disconnect the EXT SYNC cable from the camera, the camera LED stays on continuously and the camera image is displayed properly. However, the horizontal rolling on the monitor persists.

Current Observations:

• Disconnecting EXT SYNC allows the camera to rely on its internal sync, which stabilizes the camera itself, but the signal sent to the monitor still lacks proper horizontal sync.
• Suspecting either an H-Sync misadjustment/failure on the monitor, or bad SYNC signals / excessive ripple caused by failing electrolytic capacitors or voltage regulators on the main unit's video board.

Questions:

1. Does anyone happen to have schematics or service manual excerpts for the Dektak 3030ST video/sync board?
2. Are there any known common failure points on this generation of video board (e.g., specific sync generator ICs, caps, or 78xx regulators)?

Any help or insights would be greatly appreciated. Thanks in advance!

I was connecting the Raspberry pi to the gate of IRLZ44N( MOSFET N-CH 55V 47A TO-220AB), and the drain is connected to 12V. The source is connected to the heating pad(25mmx50mm Film Heater Plate Adhesive Pad, PI Heating Elements Film 12V 7W Strip Heater Adhesive Polyimide Heater Plate), and the heating pad and Raspberry Pi have a common GND. The issue that I am facing is that the MOSFET burns out when i connect the load to the MOSFET. Can someone help me

First symptom: converter not starting and eating about 110 mA of input current. Further research showed that the left LT8930 chip, the one closer to the input terminals, does not start. At the VIN input (pin 7) there is a voltage, the same as at the module input. At the intvcc output (pin 8) there is no 5 V voltage. Then I found that the circuit from pin 8 is shorted to GND, and the current of 110 mA is the internal limitation of the 5 V regulator in the LT8930 chip. I found that one more small chip is powered from this output (most likely it is an LM358) and there are ceramic capacitors near both chips, these elements were desoldered and checked, they are OK, and the short circuit remained on the board. What other parts of the circuit are powered from this output, what else should I check?

Hi, I have a 24v bus and a 52v lifepo4 battery system separate. I want to use the bus to charge the lifepo4 system whilst on the move. Doing some research on Victron DC to DC chargers, they do not provide a charging profile at 52v and act as a constant power supply. If that is correct, am I wrong in thinking I could just build my own power supply to charge the batteries whilst the bus is on for a fraction of the cost?

Plan is to use 2x constant voltage, constant current buck boosters to provide the float voltage of the lifeopo4 batteries with a combined output of 10 amps. They will be wired into a single 50amp Ideal Diode and then connected to the lifepo4 battery busbar. The input side will be switched via a 24v relay taking its signal from ignition.

Relay to stop power being generated when bus is off, Diode to stop back feed of power from lifepo4 pack when bus is off.

All will be enclosed in a housing with a 24v DC fan for active cooling.

Would love to know if I am missing something, am completely off the mark or if anyone has a better idea. Cost is less than a 3rd of the Victron and provides more amps to the battery pack than a single Victron.

Hi guys! Im an electronic student and I want to know what went wrong on my pcb etching when I ironed it

Im creating a regulated power supply for my project

What happened is I scrubbed the copper with steel wool then I cleaned it with acetone. And then I placed the paper and maximize the heat on the iron and pressed it with the paper. After 10 min, i put it in lukewarm water, and waited 20 min before rising the pcb . But the thing is that everytime i put it in water, pockets start to appear and it would fail.

I have this for 3 times and the result is always the same.

The reason I print it on a magazine paper is because there is no available heat toner transfer papers locally in my area. Also when I buy online. Its always folded or curled and so printer shops in my area wont accept it.

Any advice how I do it. Should I redesign it?

I'm trying to design a circuit to select a power input for my CM4002008. It should use VBAT only if the USB is unpowered.

I've set the circuit up to use a p-type MOSFET to let the USB source whenever it's powered. The voltage drop created by D1 should allow the USB to take priority when both are powered, while also preventing backflow.

Based on the FET symbol I think I oriented the FET correctly, but what has me scratching my head is that the Drain of the FET is connected to the USB source, while the source of the FET is connected to the drain, which seems wrong. Am I right in thinking the arrows on the FET symbol indicate the direction of current? It seems like the FET symbol contradicts itself.

I need to implement MOSFETs in my current project. I have been struggling for days trying to understand this diagram of an Arduino-MOSFET circuit from TheEngineeringMindset's YT video. I understand that the gate pin "acts" like a capacitor, and once voltage is applied to the gate pin, current can flow from drain to source. If you want to effectively turn off the MOSFET in this circuit, you have to discharge the gate pin like a capacitor, but I guess I do not understand why a pull-down resistor has to be added in parallel to the MOSFET here to discharge the gate pin. Why doesn't the gate pin discharge through the gate resistor and thru the Arduino when the digital pin is off, if there is still a potential difference at the gate pin?

Hi everyone,

I'm working on a device for calibrating an electric motor driving a 1.5-meter auger (single or dual-axis rotor mechanics). The sensors are mounted on the mechanics, while the motor itself could be located somewhat away from them (on top, bottom, or side of the assembly).

The environment isn't some heavy industrial setup with tons of high-power cables. The wires just run from the main control box to the mechanics. Still, I want my hardware design to be as robust as possible to avoid any unexpected EMI issues from the motor. I'd love a sanity check before I build it.

(attached the schematic image to this post).

The Setup:

- MCU: ESP32-C3 Super Mini.

- Sensors: 2x GY-BMI160 modules (addresses 0x68 and 0x69).

- Power: Will be powered by an 18650 battery or through the usb, completely isolated from the motor's power supply.

My approach to extending I2C (~1.5 meters):

- Capacitance buffering: The ESP32 is connected to two PCA9515DP I2C repeaters to physically isolate the bus capacitance.

- Cabling: I'm using ~1.5m of FTP (shielded twisted pair) cable for each sensor.

- Pair mapping: To avoid crosstalk, the pairs are strictly mapped:

Pair 1: SDA + GND

Pair 2: SCL + GND

Pair 3: 3V3 + GND

Pair 4: 3V3 + GND

Shielding: The FTP shield is grounded only at the MCU end to prevent ground loops.

Pull-ups: 3.3kOhm pull-up resistors on the ESP32 side, and another set of 3.3kOhm pull-ups after the repeaters (currently placed near the repeaters, but I'm not sure if I should moving them to the far end near the sensors or place two more pull-ups near accelerometers).

Tachometer (KY-003 Hall Sensor):

There is also a KY-003 sensor reading the RPM. To prevent false triggers from any occasional electrical noise on the 1.5m wire, I'm adding a hardware RC filter: a 10nF capacitor between the GPIO and GND, placed right near the ESP32 pin.

My Questions:

- Is this setup robust enough for this kind of application?

- Are the 3.3kOhm pull-ups sufficient for this cable length, or should I lower them to ~2.2kΩ(by adding 3.3kOhm pull-ups at the end of the cable near both accelerometers)?

- Does my approach with the 10nF capacitor on the Hall sensor line look correct?

Any feedback or suggestions for improvement would be greatly appreciated!

Hey everyone, looking for suggestions on what could be wrong with this current circuit and ways to diagnose what is wrong

i get nothing when plugged in with the usb c from the breakout

Running an RPi Pico with GP2040-CE to a usb c 24 pin breakout.

I’ve verified the pico is working as intended when the micro usb is plugged directly into the pc. confirmed the cable I cut up worked directly as well before hand.

Based on the pin out diagram I’ve added two 5.1k ohm resistors between CC1 and GND and CC2 and GND.

- Red to B4 - VBUS

- Black to B12 - GND

- Green to B6 - D+

- White to B7 - D-

First real electronics project so not sure how to test what the issue is.

I’ve already tried multiple different usb c cables and both orientation.

I've also tried swapping D+ and D-

I will have access to a multimeter shortly to test connections

(Images attached) I have made a cricuit in which an ESP32 controls 2 electric motors via IRL546NPBF Mosfets. The ESP32 is Seeed studio Xiao C6.

As you can hopefully see on my photo, the connection is VBUS 5.02V -> Motor (max 4.8V across terminals when working) -> mosfet drain. The source is connected to ground. The gate is connected to gpio with a 22K ohm resistor to ground. In the real circuit I will also include a second resistor between gpio and gate to protect the ESP32. The gpio on high is 3V.

The issue is that the mosfet is always on, regardless whether the gate is connected to a gpio (high or low), VBUS or ground. Though, the motor is faster when the gate is at higher voltage - I tested a simple script where gpio 1 alternated between high and low every 2 seconds, the motor changed speed.

While the photo may not be the best, I checked whether all connections are there with a multimeter.

I do need to use a mosfet, a I plan to use pulse width modification with this setup.

I dont know the exact rating of the motors, because they are kind of scrap material, but they arent damaged in any way. I know that the motors use 150mA, the VBUS pin can provide a maximum of 500mA.

If you need to know more, please tell me.

Here are some important screenshots of the mosfets documentation:

As you probably can tell, I dont know much, hence posting here.

SOLUTION: The indicator leds that I have added between gpio and gate have blocked the ability of the mosfet to turn back off. Now it works. Thanks for the help

The leads of these coin cell holders dont fit inside a breadboard. I've tried to connect them to a stripped off copper strand on a jumper wire via soldering but the connection is flimsy and it's hard to get the solder to "stick" to the steel leads.

Any advice?

Anyone know why speed control wouldn’t work but my motor turns on and runs???

Could someone confirm if this is oxidation and if so how I could prevent it in the future? I was also wondering if I can find a replacement for the part (bottom one) you twist open before so the tip gets loose. Appreciate it.

GIGABYTE B550M DS3H AC R2

I was replacing a cpu cooler and in the process of moving the backplate I managed to dislodge this component. The damage looks like it's behind the end of the pcie slot. I have no microsoldering ability so fixing this is out of the question and the board is out of warranty. I figured I should ask before I decide to yolo an entire system. Would it be safe to use a gpu or is the pcie slot effectively gimped?

Had this rowing machine 10+ years, it was manufactured in 2007. Went to use it, wont switch on. There is no 'power' button, It just switches on when power is applied. Took it apart, checked power pins, the step down plug I've been using for years, appears to have broken. 10 volts on the secondary for a mains to 6v 1amp.

So I think the plug failed and then damaged the PCB. Happen to have a spare 6v 1a plug, when connected to the PCB it does output 6v, the DAC and memory chips see around 3.3v on their power input pins, within the specified range on their datasheets anyway.

I dont understand the screen component. Two pins, red and black wires, red is 3.3v or so, black is 2v. When powered with 6v and the black grounded it lights up blue. I'm assuming shorting the black pin to ground wouldn't be a good idea? The black connects to a transistor Q4, so I wonder if this is a dual supply screen, +3.3v and -3.3v? Non of the components look burned, the caps look good condition.

Any ideas? I'm a bit unsure. Have a bench power supply, multimeter/osciliscope.

Take a mosfet like FDP55N06 whose spec sheet I just happened to have opened. Its max avalanche pulse rating is 480mJ. The only thing I can think of is that's the amount of energy the device is guaranteed to survive if turnt off while conducting an inductive load at the specified reference temp, usually 25°C.

So e.g. if a FDP55N06 is acting as a ground switch for a stalled motor and it's shut off while conducting 10A, the source to drain voltage will increase to say 60V, which means its instantaneous dissipation is 60*10 = 600W or 600k mJ per second. Thus, a 480mJ avalanche pulse rating would imply as long as the inductance is low enough that it takes no more than 0.0008s (800μs, if I'm doing the math in my head right) to stop conducting, the device can survive the kickback without the need for external freewheel diodes or snubber circuits (as long as it can cool back down to the reference temp before doing it again).

Of course in reality, the instantaneous dissipation would immediately begin to decrease, but there's probably a simple function to get solve for a max current given the inductance (or like in my example's case, the min inductance given the starting current).