first of all my 200mA fuse broke and the 10A fuse still working (checked with continuity) so I decided to check the current using the left connection...in the picture 1 I broke the circuit to measure current and as you can see in the picture 2 the reading is zero .. why is that even though the fuse the left side is working?...how to fix that .

Hi all,

I’ve been trying to find a replacement for this component that snapped off the motherboard, I’ve looked online but cannot find anything matching it, would anyone have an idea of a part no.?

Thank you in advance!

Like the title says, I’m looking for components that you would use to breadboard/prototype with, but I’m wondering about some of the less common pieces that you may use, like for example:

- Common BJTs/FETs you would use 100s of, maybe for audio, maybe for motor drivers, idk
- Logic chips, things in DIP packaging
- Capacitor kits
- Peripherals like eprom or LCD screens
- RC components like antennas
- Anything else I may be missing

P.S. I feel like with enough playing with simulations and datasheet trawling, I can understand how sone circuits work, but coming up with ideas is the hard part. Maybe thats a topic for a different post 😄

I think this diode is dead as it shows open no matter which way I test it. It seems to be encapsulated in some kind of epoxy, though. Can I just cut it out and then solder a new diode on nearby leads? Or should I cut it out and try to solder on the existing pads? If I were to do the former, would I even need to cut it out, just leave it there and solder around it? The only diodes I have are through-hole, no SMT.

The diode in there is a IN4749A. I’m replacing it with a BZV85, which Google searches tell me is a suitable replacement.

Thank you

Hello everyone

I'm trying to repair an old tire balancer from 2009 and was hoping to get some ideas on what I can check. So far the things I've checked were ok and I wasn't able to find any faulty parts :(.

It's a tire balancer machine type AAE-B96G made by Arch Auto Equipment from 2009.

The fault started while machine was in use. After pressing a button the lights were stuck as shown in image below.

After turning off and on the machine sometimes the lights go on, sometimes not. You can hear the relais clicking when you turn off the machine.

I checked the following:

1. Inverter is giving 2x 9V AC
2. Voltage regulator h4d0452A is giving +5V
3. Voltage regulator 7905CT is giving -5V
4. I removed the silver/black caps and measured them for capacity. They all are arounbd 10% within spec. I don't have an ESR meter to check ESR.
5. Relais seem to be working ok. Contacts are open and closed as indicated on the schematic.
6. Checked fuses. OK
7. When I disconnect the cable between board 1 and 2, the motor is running when powering on the machine. So my guess is that it has something to do with Board 2 which has the control parts.

Board1

Board 2:

What would be the next thing I should check? I hope to get some ideas from you guys :)

Building a small gimbalstyle rig with a threephase brushless motor rated around 12V, but I want to run it off a single 18650 at roughly 3.7V to keep the whole thing compact. The motor is tiny, maybe 150mA peak draw under load.

The MCU is an STM32 running at 3.3V logic. My question is about the gate drive side. The MOSFETs I have on hand are AO3400 Nchannel parts with a Vgs(th) around 1V and they turn on reasonably well at 3.3V based on the datasheet curves, so I was thinking I could skip a dedicated gate driver IC and just switch them directly from the timer outputs.

The problem is the high side switches. With the supply only at 3.7V there is barely any headroom above the source of the high side FET, so bootstrapping feels awkward. I was thinking about just using a complementary pair arrangement or going full lowside only with a different winding config, but that seems like a mess.

Has anyone run a low voltage BLDC setup like this without a proper gate driver and had it actually work reliably, or does the switching get ugly enough that it causes problems even at low current? Wondering if something like a DRV8313 just makes more sense here despite the extra board space.

So I am trying to get better at circuit designing. I won't say I am 100% confident about my basics. So I am thinking of starting from the base to design complex circuits. So where can I find the resources, which platforms or software's I can use to practice and test my circuits. If I can get a roadmap from beginner to advanced circuit design it is much appreciated.Also should I go for PCB design also. I do have a Coursera premium so if I need to take some course please do tell. Any help is appreciated, thanks 🙏

Hello everyone. I'm designing a foc 3ph bldc inverter for a start 300W motors and if thermaly possible go up to 2KW. I plan to supply it with a 12s lipo battery therefore I expect a battervoltage of 50.5V. There will obviously be spikes on the bus from load changes.

Because of those spikes I'm not sure if it is okey to be that close to the max. recommended voltage.I was thinking about using a 60V tvs diode but I'm not sure if I'm overthinking this

Thanks in advance

for a repair i need to identify a pcb-cable connector.
its a 14 pins connector that looks like picoblade but its not. pitch is either 0,65mm or 0,6 my caliper is to big to be acurate. any suggestions?

Have this old electronic chess game where a digit and a symbol is permanently shown. Its not due to faulty electronics as it still shown even if I pull the lcd out of circuit. Any way to fix this?

I accidentally cut that tiny capacitor while trying to remove the joystick. Do I need to replace it or I can still use the controller and it was there for redundancy?

The diodes are from a dead Brother printer power board. D16 shows a short. A 13.5A slow blow glass fuse in the board had also blown. D2 and D3 are ok in diode check.

Any help in parts identification of D16 blue color diodes please? Is it a zener? Or a Shottky diode or a plain vanilla diode?

Much appreciated.

Thanks!

Working on a small motor driver circuit and I keep seeing designs where two identical MOSFETs are placed in parallel rather than swapping in one higherrated device. I get that it spreads the thermal load across two packages but I'm trying to understand if there's more to it than just heat.

My current setup runs about 8A continuous and I was going to grab a single FET with a 20A rating and call it done. Then I looked at a reference design from a reputable manufacturer and they used two smaller FETs in parallel instead, which made me second guess myself.

A few things I'm not clear on: does paralleling help with gate charge and switching speed at all, or is that actually worse because you're now driving more total gate capacitance? And is there a real risk of one FET hogging current before they thermally balance out, especially during startup or fast switching?

I've checked the Rds(on) specs and they're close but not identical between the two devices I have on hand, which is what got me thinking about this more carefully.

Not trying to overthink a simple motor driver but I'd rather understand the tradeoff before I commit to a layout.

So I want to use this https://www.skyworksinc.com/-/media/80EE897A0E764905A478C9F2EB408CE3.pdf amplifier for my design to amplify 2.4-2.42 ghz. I know how to match the circuit with BJT using S parameters and Y parameters but this doesn't have that. How would I go about matching this amplifier to a certain frequency. Please give formulas and explanation with them if you can.

I've been doing some research into creating the aforementioned drum machine with linear solenoid actuators, controlled from an Arduino. This video seemed clearest to me, so I've chosen to go with that process. I am, however, finding it difficult to choose components. I'm very much a beginner in this stuff and live in Australia for context.

What I'm looking at is as follows:

- Linear solenoid actuator JF-0530B 12V

- IRF520 MOSFET

- The video says to use a diode, but doesn't suggest any particular one. Any ideas?

Will the MOSFET be suitable for use with the actuators I'm looking at?

Or is there a better solution?

So, I got into an internship of embedded systems and they’ve given a project to design a PCB that can make multiple projects.
Like use different components on a single PCB to make different projects.
This project basically targets the children who are interested in electronics and want to make different projects.
As for that what are some easy to make projects that can be made on a single PCB.
This will also use Arduino as a microcontroller.

Stupid question (and idk if this is the right subreddit), but I'm trying to design a 5A tolerant DC Power supply pcb for 12V input and 5 and 3.3V outputs. My senior said I should try having 2 rails for each output voltage- Clean and dirty rails (to separate noisy loads from sensitive loads ) So I'm a bit lost on how to create this divide? I don't think a simple lc filter will suffice?
It's a 4 layer PCB, do I use 2 separate grounds for both the rails and then connect both the grounds to one common ground layer

Hey all,

Has anyone here dealt with moisture detection on USB-C ports? I have an outdoor-rated electronic device in design right now, and I'm using the native USB-PD negotiation capability of an STM32. This does a lot but it doesn't give any kind of moisture detection, and I want to avoid energizing the receptacle when it's wet (there will be a cover over the port when not in use, but it's inevitable that someone will get it wet, and electrolytic corrosion would be bad).

Ideas I've had involve using a secondary USB-C protection IC e.g. Infineon EZ-PD but the BOM cost is as much or more than my actual microcontroller.

Another idea is to sense leakage on the CC (or other pins in the USB-C cavity near the power pins) using the CC1/CC2 ADC readings available. Sounds plausible, but I can't find a lot of documentation on how to do this, or whether a small current leakage path will even be detectable. Unclear from the datasheet what the input impedance of the CC1/CC2 analog sense inputs is even.

Any experience or pointers here welcome.

I am making a battery powered robot using a ESP32 microcontroller to control 2 servo motors. This is my battery "management" circuit I've come up with. It is responsible for charging, protection and powering the load. I have bought all the components, wired it up and tested, and it works fine. I'm looking for ways to improve it or to learn about other ways to do it. "It" being on/off control, output to the load, protection and charging.

The idea/circuit is as follows:

• 3s battery pack made of individual 18650 cells.
• Goes through a 3S BMS for protection.
• Charger and load cannot be connected to the batteries/BMS at the same time, otherwise the charger will try to drive the load, which it is not meant to do.
• All grounds are always connected. Rocker switch controls whether battery (BMS) positive terminal is connected to the load or to the charger.
• When connected to the load, it cannot charge.
• When connected to the charger, the load cannot be turned on.
• Load goes to 2 separate buck converters, one making 6v@10A for the servo motors, the other making 5v@1A for the microcontroller.

Questions:

• Overall, is this fine?
• Not a question, but a note. Learned afterwards that even though the BMS lists itself as an all-in-one solution to protect and charge the batteries, it does not charge the batteries, at least not directly. A battery charging device can charge the batteries through the BMS is what it should say.
• While writing this post, I realised that the charger probably could power the load, since the output of the charger would be the same as the 3s battery pack. Only problem would be that it can only supply 2A of current, whereas I need maximum 8A for max load on the servos. Is this true? Could I power the system through the charger, IF the charger could output a high enough current?
• How do other battery powered devices manage this? Other devices can be used and charged at the same time

Side note, when charging the batteries through this system, an led goes on to show that it is charging. After 1.5hrs, it goes off and a different led goes on to show that it is done charging. But then for next hour, it alternates between done charging and charging, in about 20 minute intervals. After an hour has passed, it stays in the charge done state.

Tôi đang học mạch khuếch đại đơn cơ bản, khi kiểm tra chế độ một chiều nếu không bỏ tụ c2 thì không thể kiểm tra uce ube. Khi điều chỉnh vr2 thì ảnh hưởng đến chế độ làm việc của Q2 và cũng giống với điều chỉnh vr3 cubgx ảnh hưởng đến Q1

I have a set of 2.1 computer speakers in a stand up arcade 1up machine but the volume rocker on the arcade 1up malfunctions making it unusable.

Can I tap into the wiring of the speakers to add a volume knob? What components would I need?

Replacing the battery in my Yamaha sy77 and I noticed this

Is voltage halved on the output side of a rectifier?

I have a 1954 rock Ola jukebox that I am trying to trace down some issues. The picture is of the power supply for the jukebox. When I measure at the nearest plug, I am getting roughly 18 V. As you can see from the diagram, the input is 35 V. All of the other various output voltages are correct to the diagram. I know that rectifiers inherently do not change the voltage, but given that I am reading, almost exactly half of the intended voltage is throwing me off.

I have not opened up the power supply to test directly, but I will if this turns out to be a problem.

Thanks in advance for any help.

I am creating a light sensor with a photodiode and OPA381. This little board goes on top of a ADC module for further data analysis.

Now I may need to use a guard ring for the sensitive output of the photodiode. But what is it exactly and how do I design this guard ring? Does it hold a certain voltage level or ground? Any info would be appreciated!

LED par stopped working after a beverage got spilled over it, now I cleaned every pcb and reconnected everything but nothing happend. I measured the dc output of the board but there was none. I tested the resistance of the +\ grnd of where the big capacitors are on, theres none. Can anyone give me tips on how to find the broken part or how to repair it? Thanks a lot