hybridfree/eevblog-posts huggingface dataset:
confused with connecting the BMS balance wires  - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: March 22, 2018, 01:46:05 pm
content: hello friends,I'm planning to make a 4S1P battery pack. I'm using a BMS with balance charge function. But I'm so confused with the 5 balance wires that could be connected to the connector on the board. I have attached a pic of the BMS board that I'm using in my project. My question is , apart from the balance wires there are 7 silver pads i.e P+, P-, B+, B-, B1, B2, B3 on the board. I have already attached wires from these silver pads to the respective terminals as shown in the second pic. But what should I do with the balancing wires?? these are also named to connect in the same terminals as of the silver pads so what should I do ?? Should I short these balance wires to the silver pads for the balancing to work or I just don't connect it assuming that its an additional setup for those who don't wishes to solder to the 5 terminals(B+, B-, B1, B2, B3) on silver pads.

author: hli
author_rank: Frequent Contributor
timestamp: March 22, 2018, 03:07:34 pm
content: P+ and P- got to the output (or the charger when charging). B+ and B- go to the most positive and most negative end of your battery stack. Then B1,2,3 go to the connections between the cells. Connect them as indicated in the second picture. When your battery pack already has balancing wires, they go to these connectors on the BMS. When you have 5 balancing wires, the outer wires should to to B+ and B-, and the inner ones to B1,2,3. Measure the voltages, respective to ground, to make sure you get the correct order of the wires.

author: Adhith
author_rank: Frequent Contributor
timestamp: March 22, 2018, 04:02:39 pm
content: Thank you for your reply. The connection diagram shows the connections that I have done. I have already soldered with some different wires ( not the wires that came with the circuit) to the silver pads on the board. What I'm confused is with the white plug on the board and the balancing wires that came with the circuit. My question is should I again connect the balancing wires in the plug and solder it to the silver pads, since I have already taped wires to all the respective terminals on the battery pack . I just want to know that do I need both the connection from the silver pads and the white plug ??

author: hli
author_rank: Frequent Contributor
timestamp: March 22, 2018, 09:34:10 pm
content: Without knowing in detail about your BMS: the white plug is a balancing connector, so you can directly plug in a battery pack. This is useful for packs that come with such a connector - in contrast to a pack you make by yurself where you want to solder the wires.So you need only one of the connections - either use the connector, or solder wires. You can do both, it should not hurt (unless you mix up the order of the wires), but makes no sense.
Confusing Dual Polarity HV Pulse Generator in AoE 3 X-chapters - Page 1
Forum section: electronics / beginners

author: niconiconi
author_rank: Frequent Contributor
timestamp: January 26, 2022, 01:18:45 pm
content: I need a high voltage pulse generator circuit for a simple experiment - testing the pulse-energy endurance of different types of surge protection devices, such as TVS, Thyristor Surge Suppressors (TSS), and Gas Discharge Tubes (GDT). The idea is simple, charge up a capacitor from a DC-DC converter, and dump the current to the load via a MOSFET switch. I found the Art of Electronics, 3rd Edition, X-chapters has exactly what I need. Even better, the section is available at the authors' website.https://x.artofelectronics.net/wp-content/uploads/2019/11/3xp15_HV_pulsers.pdfThe authors' suggested two pulse generator designs for reversible polarity. The first design is straightforward - the MOSFETs are floating and controlled by isolated gate drivers, a mechanical relay connects either the positive or negative HV terminal to the common ground. Thus, you see a positive pulse or a negative pulse with respect to ground.Later, they also suggested another design with an electronic polarity control. As you see, Q1 or Q2 pushes either the positive or the negative rail to the output. The back-to-back MOSFETs Q3 and Q4 form a bidirectional switch to pull the output back to ground.Initially I couldn't understand how the common ground is connected. I assumed it's just an electronic version of the previous relay design, and the HV supply can be switched to meet the common ground at either side. But I was baffled because there appears to be no return path at all. For example, if HV is disabled, the output of the two AND gates are false, Q1 and Q2 turn off. I believe the positive pulse capacitor cannot charge up because there's no return to HV-, and the negative pulse capacitor cannot return to HV+ either.After staring at this circuit for a while, I think I found out the reason: the relay design only requires a positive HV power supply, but the MOSFET design requires a bipolar HV power supply with the mid-point already connected to the common ground. Yet it was not mentioned anywhere in the explanation - a serious omission and it's really confusing.But I'm not entirely sure, so I'm posting here for a confirmation. Was my conclusion correct, or did I miss something?
Confusing jargons - Page 1
Forum section: electronics / beginners

author: Keosintal
author_rank: Contributor
timestamp: October 03, 2018, 11:34:09 am
content: I read Fluke 88V user manual. It states in accuracy specification: "AC conversions are ac coupled and are average responding, rms indicating".What are the meanings of:1. AC conversion2. AC coupled3. RMS indicatingThe model is not a true rms meterBeen Googling for hours and nothing useful. What do they mean? Thanks.

author: Nitrousoxide
author_rank: Regular Contributor
timestamp: October 03, 2018, 12:13:09 pm
content: 1. This just states that it will convert an AC waveform into an equivalent DC RMS value that the multi-meter can display.2. AC coupled just means that the AC mode only reads AC values, this is more likely due to a capacitor being in series in the front end.3. RMS indicating just means the units are displayed in Vrms ( Vrms = 1/sqrt(2) * Vpp).Because it isnt a true RMS meter, you will only get accurate results with single tone sinusoidal waveform as that (ideally) has no harmonics.

author: macboy
author_rank: Super Contributor
timestamp: October 03, 2018, 02:22:05 pm
content: Quote from: Keosintal on October 03, 2018, 11:34:09 am"AC coupled" means that it will block DC, and only pass AC (above a certain frequency which is not specified). So if you have a voltage source with both AC and DC components (e.g. a voltage rail with some ripple), it will measure and display only the AC part, ignoring the DC part. This is actually helpful, if you want to measure the ripple on that voltage rail for example."RMS indicating" is not to be taken alone, instead consider: "average responding, RMS indicating". That means that the meter will determine the average of the (rectified) AC component of the waveform, then apply a correction to approximate an RMS value. Note that the average of a rectified sine wave is 0.637 of its peak, but its RMS value is 0.707 of the peak. So when the average value of the AC voltage into the meter is (for example) 63.7 V, the display will show 70.7 V. This is an accurate representation of the RMS value of a sine wave, but if the input is not a sine wave, it will be inaccurate to a varying extent.
Confusing Results Trying to Pinout a connector - Page 1
Forum section: electronics / beginners

author: MGaddict
author_rank: Contributor
timestamp: June 20, 2022, 12:37:20 am
content: I am trying to figure out the pinout for a connector and the pins appear to be connected to multiple pins on one of the chips.I acquired a Texas Instruments Extensa 650CD laptop from 2006. The HDD caddy was missing and Acer, the actual manufacturer of the laptop, used a Hirose FX2 40pin connector to go from the motherboard to the caddy that holds the hard drive. (Thank you Fraser for helping me find that connector.) Since the standard 44pin 2.5" IDE connector only actually uses 41 pins and 5 of those are ground, they just combined 2 of the grounds to get it on 40pins.I found the technical manual for the laptop which has pin outs for most of the chips and connectors on the laptop and tons of other schematics. However, it doesn't have the pinout for this connector, at least not that I can find. That being said, I do have the pinout for the ALi M1523 that is responsible for IDE. Since IDE is a very standard connection, I figured this was going to be a super simple problem of matching the pins on the connector to the chip so I could determine what was what and then I could easily make an adapter. I am simply using a multi-meter in continuity mode to pick a pin on the connector with one prove, then slowly drag the other probe across the pins on the chip listening for a beep.Unfortunately, I'm running into a problem where each pin on the connector appears to go to multiple pins on the chip. For example, pin 1 goes to ground, and IDEPCS1J, and IDRQ0, and a few other places. The pin next to that goes to IDE_D8 and IDE_D1.None of this makes sense. The laptop boots fine from a floppy disk. The PCMCIA works fine. I have double and triple checked that I am not crossing something with my probes. I also show a high resistance between most of the data pins on the M1523.Honestly, this is very defeating, I thought this was going to be so easy. Either I'm doing something wrong, or I'm missing something. I have pinned out connectors before and built custom adapters. This isn't a first attempt.Any suggestions what so ever about how I can get the pinout of this thing?Link to manual I downloaded:https://www.manualslib.com/manual/482126/Texas-Instruments-Extensa-60x-Series.html
Confusion about available test/analysis gear (myRio, AD2, myDAQ, RP) - Page 1
Forum section: electronics / beginners

author: crashtest84
author_rank: Newbie
timestamp: November 14, 2017, 03:47:27 pm
content: I'm looking at myRio, AD2, myDAQ, and Red Pitaya but I'm not sure which one would give me the most mileage. I do hobby/school projects where I think a range of tools would be helpful:- I2C/UART comms (Pixhawk)- PWM (ESC/servo control)- Old-school analog audio repair (Tube amps (guitar), power amps, mixing consoles, etc)- Sensor analysis (IMU, magnetometer)I'm finishing a drone project this semester and plan to continue working on autonomous robotics, both ground-based as well as aerial systems. I'd be open to suggestions other than what I've listed but I'd really like to stick to low-cost portable solutions. I have no plans to use LabVIEW for anything, since I plan to use the hardware after my academic discount expires and I don't want to be reliant on paid software.Also, I'm really fuzzy on what the difference is between the myDAQ, myRIO, and AD2. I've read through the spec sheets and even talked with NI about them but I don't think I understand the tools well enough to understand why the myDAQ is listed at 2x the price of the AD2 and why the myDAQ would be a better option than the myRIO which appears to be priced the same as the myDAQ.I already own a multimeter and I plan to buy a dedicated power supply so I don't really care if this device provides those features.
confusion about pull down resistors - Page 1
Forum section: electronics / beginners

author: engineheat
author_rank: Frequent Contributor
timestamp: January 26, 2018, 01:28:56 am
content: I get the idea behind pull up resistors. You want the pull up resistance to be much smaller than the input impedance of the pin, so that with voltage division, you'd still have an input voltage close to 5V at the pin input.Here's how I understand it, X marks the voltage at the pin input5V ----pull up resistance ----- X ------- input impedance ----I'm a little unclear on pull down resistance, specifically how large the value should be. One source says pull down resistance should be much larger than input impedance, like this one:http://www.resistorguide.com/pull-up-resistor_pull-down-resistor/but the reason they gave is not intuitive.Another source talked about current sinking/sourcing at the pin, which confused me. Other sources like Sparkfun only glossed over pull down.Please advise on the appropriate value for pull down resistor, and briefly explain why.Thanks

author: rstofer
author_rank: Super Contributor
timestamp: January 26, 2018, 01:47:16 am
content: I can see why you are confused, the web page is just wrong. There is a solid Vdd going to the pin when the switch is closed and the resistor value doesn't matter assuming you don't overload the power supply and there is NO chance of that with CMOS where the pin current is negligible and the only current is through the resistor.This is fine for CMOS but, again, TTL is a different story. The resistor needs to sink the pin current and still hold the pin below the threshold. That takes a low value resistor and, for that reason, pull-down isn't usually used for TTL. Nobody is using TTL so I'm not going to show the math.Given that the CMOS current is negligible, the only current flowing through the switch goes through the resistor. It still needs to be high enough to make the switch reliable. I prefer a low value like 1k.

author: David Hess
author_rank: Super Contributor
timestamp: January 26, 2018, 04:19:10 am
content: CMOS has essentially an infinite input resistance so the pull-down or pull-up resistance is limited by capacitance and how fast the rise or fall time needs to be.TTL has an asymmetrical current driven input so its pull-up resistance is high and may be limited by capacitance but its pull-down resistance if used has to be very low. Some of the last TTL families built on complementary bipolar processes had PNP inputs reducing the pull down current considerably but really it was never a problem.

author: Zero999
author_rank: Super Contributor
timestamp: January 26, 2018, 09:37:07 am
content: Check out the following thread:https://www.eevblog.com/forum/beginners/trying-to-understand-a-pull-up-resistor/msg1407317/#msg1407317

author: danadak
author_rank: Super Contributor
timestamp: January 26, 2018, 11:24:57 am
content: Pulldown R's often used to absorb leakage in CMOS designs, to preventan input or external transistor from turning on when driving pin is tri-stated.Examples of UP's driving external power switches -Regards, Dana.
Confusion about using a comparator to generate a square wave - Page 1
Forum section: electronics / beginners

author: Peeps
author_rank: Contributor
timestamp: July 14, 2018, 04:50:55 am
content: This circuit which I found in an industrial electronic device uses an LM339 comparator to compare the offset sine wave to a reference voltage of 5V and creates an inverted square wave as a result. From what I've read, R2 exists to feed back some of the output to change the reference slightly to create a hysteresis effect although in simulation the reference voltage hardly changes.What I don't understand and haven't quite been able to figure out is why the output square wave never goes above 5V. Regardless of the supply voltage, the square wave maxes out at 5V. I feel like it should go as high as Vcc but this is not the case. Can someone help this fool understand why?

author: oPossum
author_rank: Super Contributor
timestamp: July 14, 2018, 04:56:17 am
content: Comparators are usually open collector or open drain. They will sink current, but not source current.

author: JS
author_rank: Frequent Contributor
timestamp: July 14, 2018, 05:22:29 am
content: The voltage change would be only 1/121, since the ratio of the resistors is such. The reference won't change, but effectively it does by shifting the input signal by that ammount on the non inverting pin. There you will see a small jump when the voltage crosses the threshold. That's there as you said to generate hysteresis, so the noise while crossing the line doesn't make the output to jump back and forth before settling, or if the voltage crossing is too slow, the output could act as a linear amplifier making strange things, for this circuits you usually want some ammount of hysteresis.JS

author: Peeps
author_rank: Contributor
timestamp: July 14, 2018, 07:35:41 am
content: thank you, I knew I was missing something obvious and that was it. I kept thinking about it in terms of a traditional op-amp and not a comparator.

author: JS
author_rank: Frequent Contributor
timestamp: July 14, 2018, 02:53:14 pm
content: Quote from: Peeps on July 14, 2018, 07:35:41 amMore like the opposite, it has POSITIVE feedback so it doesn't want to be stable, one state one the other, wich makes it stable (against the rails) and once it's there id doesn't want to go to the other state, it preferes to stay, till the change is big enough.JS

author: mikerj
author_rank: Super Contributor
timestamp: July 14, 2018, 05:46:57 pm
content: Quote from: JS on July 14, 2018, 02:53:14 pmIt haspositivefeedback, in order to provide hysteresis.

author: JS
author_rank: Frequent Contributor
timestamp: July 14, 2018, 08:44:22 pm
content: Quote from: mikerj on July 14, 2018, 05:46:57 pmYes, it does, thanks.JS

author: Zero999
author_rank: Super Contributor
timestamp: July 14, 2018, 10:27:23 pm
content: Another option is to use a comparator with a push-pull output, such as the LMC6762 or TSX3702.http://www.ti.com/lit/ds/symlink/lmc7211-n.pdfhttps://www.st.com/resource/en/datasheet/tsx3702.pdf
Confusion between TTL and CMOS level for serial communication - Page 1
Forum section: electronics / beginners

author: sean87
author_rank: Regular Contributor
timestamp: November 23, 2012, 02:07:18 pm
content: Hoooi, welcome to teardown tuesday! oh no I am just joking!I am pretty much confuesd about making a serial connection between a Roomba robot that it's manual says it uses TTL level and a TI MSP430 microcontroller that I am working on and its powered by 2 AA batteries that is 3 Volts (But yeah I read only 2.6 on the multimeter).So the Roomba says it uses 0 - 5V TTL logic.My TI controller (on a test board) is 0-3 Volts I guess (Considering that its supposed to run on 2 AA batteries).What I want to know is, is it safe to connecto the roomba directly to the TI chip? If yes, according to wikipedia CMOS level low is 0 V to VDD/2 and for high is VDD/2 to VDD. Am I going to get corrupted data?Please let me know your thoughts, I am a complete noob

author: 8086
author_rank: Super Contributor
timestamp: November 23, 2012, 02:18:51 pm
content: Depends which TI chip you're using. You could hook up a resistor divider to the roomba's output, to keep your chip safe.Valid levels will vary depending on the devices, it's not always a case of 0-50% low, 50-100% high.Look up some datasheets.

author: hlavac
author_rank: Frequent Contributor
timestamp: November 23, 2012, 06:04:54 pm
content: Classic CMOS thresholds are 0.3 Vcc for LOW, 0.7 Vcc for HIGH. For very low voltages they may be 0.25 / 0.75 to keep the levels apart enough because noise is relatively bigger.TTL has <0.7V for low, >2V for HIGH.You can simply connect msp tx to roomba rx.Connect roomba tx to msp rx thru a few k resistor, input protection diode will do the clipping for you.

author: sean87
author_rank: Regular Contributor
timestamp: November 29, 2012, 10:21:45 pm
content: Quote from: hlavac on November 23, 2012, 06:04:54 pmThanks. Can you please tell me what do you mean byinput protection diode will do the clipping

author: hlavac
author_rank: Frequent Contributor
timestamp: November 30, 2012, 05:54:12 pm
content: Input protection diodes will not allow the voltage level on the input to go above chip's Vcc + one diode drop or below gnd - one diode drop.The rest of the voltage will drop across the 10k current limiting resistor.
Confusion on current limiting resistor for LCD - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: February 09, 2019, 07:30:15 am
content: Hi everyone,I decided to swap some old black on green LCDs with white on black LEDs from china ebay sellers.I soldered pin headers on and it all works, but, i think i need a current limiting resistor. The backlight is so bright, it almost looks blue and looks light-grey in some parts.When i google about the current limiting resistor, i see some suggestions to put a resistor between VSS and K, is this what i should do? I would have to solder it to the other side of the pin header i think.This is exactly the display i have:

author: ataradov
author_rank: Super Contributor
timestamp: February 09, 2019, 07:42:07 am
content: Backlight is a completely separate circuit. It is connected only to A and K pins. And there is usually a place on the module itself to install the resistors, and they usually are installed. In case of this picture It looks like R8 and R9 are related, but the picture is too low res to tell what is going on exactly.Look at your display near A and K pins, or take a good picture.

author: mariush
author_rank: Super Contributor
timestamp: February 09, 2019, 08:31:37 am
content: Like ataradov says, the backlight is separate. In the picture you linked, R8 is a current limiting resistor, but it may be a 0 ohm resistor or a very low value by default, so it would allow too much current to go through the backlight.You can add a resistor in series, on either the anode pin or the cathode pin, doesn't really matter which one as long as there's a resistor in series.You have the formula V=I/R so ... the resistance value is basically [Input voltage - Forward voltage of led(s) ] = I * R .... with a 3.2v led and 5v input and 20mA (0.02A) ....you have R = (5-3.2) / 0.02 = 1.8 / 0.02 = 90 ohm, so a 100 ohm resistor would be good enough, or a 82 ohm resistor would also work if there's already another small resistor on the back of that display.You could also have a 47 ohm resistor in series with a 100 ohm trimpot (tiny potentiometer) which would allow you to adjust "brightness" between 47 ohm and 147 ohm, so you have super bright or dimmer. Values are random, you can pick whatever values you want.
Confusion on motor brake design. - Page 1
Forum section: electronics / beginners

author: weatherjack
author_rank: Newbie
timestamp: June 06, 2022, 10:37:47 pm
content: I am building an R/C platform that I will eventually be using for autonomous testing and design. The base for this project started out as an electric wheelchair. I am driving the motors with a Sabertooth 2X60https://www.dimensionengineering.com/products/sabertooth2x60. The motors have electromechanical brakes that need 24v supply to turn them off. The brakes can also be released with a lever on the motors themselves to allow free wheel (being pushed by hand). I have a drawing that I found online that will allow the motors to be driven in both directions while releasing the brakes. This will also allow the motors to be freewheeled without flyback (correct?) being fed back into the circuitry. I am using distribution blocks for all of the connections to assist in trouble shooting and upgrades. I am attaching the original drawing and what I have come up with. Does this look right or am I missing something? Thanks.

author: CaptDon
author_rank: Super Contributor
timestamp: June 07, 2022, 01:34:04 pm
content: If you are going to vary-speed the motors the brakes possibly won't release at low speed / low motor voltage. Other than that, your circuit seems like it should work.

author: weatherjack
author_rank: Newbie
timestamp: June 07, 2022, 05:49:17 pm
content: Thanks for looking. This one took way to long for me to ingest. I am hoping voltage will not be an issue. I do not see any other way around this without removing the brakes physically and that is not an option for me. Thanks again.

author: mikerj
author_rank: Super Contributor
timestamp: June 07, 2022, 06:40:42 pm
content: I'd suggest the original speed controller would have supplied a constant 24v to one side of the motor and PWM to the other side, which would ensure the brake would always see a full 24V.

author: weatherjack
author_rank: Newbie
timestamp: June 07, 2022, 10:20:14 pm
content: mikerj I think you are correct. I never opened the original controller. I still have it if anyone is interested? Thanks for the input.

author: weatherjack
author_rank: Newbie
timestamp: June 07, 2022, 11:35:11 pm
content: Ready to install. Thanks for the input.
confusion over connecting power via charging socket vs direct to cell ? - Page 1
Forum section: electronics / beginners

author: carpetpaul2129
author_rank: Contributor
timestamp: July 13, 2022, 08:23:41 pm
content: ok, I'm learning, and struggling with certain concepts.I've made a couple of battery packs now with BMS, those measured voltage at the charging socket, charged and worked fine, I was able to measure the voltage at the output terminals (or charging socket) which is all good, however on other devices, there has only been a charging socket available...I've then encountered a couple of other battery packs which are different, firstly the 60V pack on my electric scooter which registers just a few milliamps (seems to be a recurring issue) at the charging socket, and also a very small single cell 3.7v cordless screwdriver (without charger) which I've just repaired with a new cell. It measures no meaningful voltage at the charging socket, but I know the cell is good (not fully charged) connected to my power supply, set 4.2v and .5amps as maximums, but its drawing almost nothing, it's 4.2v / .06amp . .25watt.(power supply is set at 4.2v / .5amps, and is on CV at the moment)Oh... to have knowledgeIs this a BMS that's expecting a particular amount of power to allow charging ?I love this subject, I just wish I understood a little moreplease help

author: carpetpaul2129
author_rank: Contributor
timestamp: July 13, 2022, 09:16:09 pm
content: Might be obvious, but I notice that turning up the amp limit does nothing, still seems to go very slow, I wonder if this is a knackered BMS, and the reason for this old tool not charging and becoming discarded to the back of a cupboard ?
Confusion regarding LC tank circuit - Page 1
Forum section: electronics / beginners

author: medical-nerd
author_rank: Regular Contributor
timestamp: May 18, 2017, 03:38:32 pm
content: HiyaI've been looking at LC tank circuits and have become confused.As I understand it when the reactance of the inductor and capacitor are the same it behaves as an open circuit for AC signals.Is this the same as when it is in resonance, if so how can it act as a tuner for rf signals?Also can a DIP meter be used to find the resonant frequency if the inductor is using a toroid core, I thought the magnetic field was confined in these.If a DIP meter can be used, what orientation should its coil be in relation to the toroid?Cheers

author: w2aew
author_rank: Super Contributor
timestamp: May 18, 2017, 03:57:02 pm
content: The impedance of an parallel LC circuit at resonance looks like a high impedance (open), but the impedance of a series LC circuit looks like a short at resonance. Here are a few videos I did on LC circuits and resonance:And here's a video I did on the DIP meter. For toroidal inductors, try orienting the dip meter coil so that it's turns are parallel to turns on the toroid along the outer perimeter, you should be able to couple sufficient energy for it to work:

author: medical-nerd
author_rank: Regular Contributor
timestamp: May 18, 2017, 05:10:14 pm
content: Many thanks w2aew for your informative videos, you have made resonance of a parallel LC tank circuit much clearer to me.So as I understand it, when there is an rf signal with a frequency that matches the resonant frequency of the parallel LC tank circuit, the circuit is open to ac signals so maximum signal is passed, rather than be shorted to earth.Using a variable capacitor changes the resonant frequency, so allowing different input frequencies to be selected.Is this correct?Does a regenerative receiver feedback the output of/to the parallel LC tank circuit so making it oscillate?What coil have you attached to your frequency counter to check the frequency of the DIP meter? Do you use an amplifier for picking up the signal?Cheers
Conjoining usb devices into single power source? - Page 1
Forum section: electronics / beginners

author: deanjones84
author_rank: Newbie
timestamp: April 20, 2020, 01:28:00 am
content: Hi guys,Complete novice know-nothing here, just wondering if you could help me out..I have 6 USB powered devices seperate to each other that I want to link up to a single power source (Portable battery). Each are 2.5W, 5V DC.Would the easiest option here be to get a 6-port adapter or wire it myself (I can solder)? I'm not even sure if the adapter would lessen the output, and also what size battery I should get to make devices last around 1/2hr-1hr. That's how inept at this I am sorry!Any help greatly appreciated, cheers!

author: Manul
author_rank: Super Contributor
timestamp: April 20, 2020, 01:48:48 am
content: So thats 3A at 5V. Easiest idea seems to be USB C power bank. But I don't know if USB C power bank will give output without a device comunication. Maybe someone tried and can confirm?
Connect a smartphone LCD display to laptop HDMI port - Page 1
Forum section: electronics / beginners

author: hatmadder01
author_rank: Newbie
timestamp: October 24, 2014, 09:33:08 pm
content: Hello All,To begin with, I am new to this forum and pretty much new to the electronics world, just sparked an interest recently.Now, on to the project, recently one of my friends had his HTC One smartphone dysfunctional. After investigation he was told the main board is gone, however the LCD display is still working, which he agreed to give me for 10 bucks. Now I am trying to find a way to connect it to a computer. The primary aim is to hook it up to a small board like Raspberry Pi or Beagle Board to make something useful out of it.So the question here is how do I hook up the display to a full fledged computer. I read around and figured that the display is a 1080p unit from JDI and has a MIPI interface, which I figure is the latest standard interface for displays. Also what I figured is that I would need some sort of a Display Controller board which would take HDMI or VGA in from the laptop and interface with the LCD via MIPI. Where I am stuck is I don't know where to find such a controller board and what exactly I am supposed to google for to find a display.I wrote to JDI and they responded back saying they don't deal with individuals unless they represent a company regarding business. Any help in understanding the concept of display boards and where can I find a cheap one is greatly appreciated.Best,Dash

author: wraper
author_rank: Unknown
timestamp: October 24, 2014, 09:53:07 pm
content: You wold need to reverse engineer this display and make a custom interface converter by yourself. Time to learn FPGA.

author: miguelvp
author_rank: Super Contributor
timestamp: October 25, 2014, 03:47:23 am
content: And this would be a good departing start to do so:http://hackaday.io/project/364-mipi-dsi-display-shieldhdmi-adapterAlthough I've seen cheap LCD controllers connected to small phone factor displays via lvds but I will think the HTC One is a MIPI interface.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 25, 2014, 04:02:59 am
content: Google returned 16,400 results when I searched for: mipi lcd controller hdmiDid NONE of them look useful for what you are trying to do?This seems like a very complex project for someone asking such basic questions.Do you have the pinout for the display? Without that you are in very deep waters.

author: Rasz
author_rank: Super Contributor
timestamp: October 25, 2014, 04:38:05 am
content: Quote from: hatmadder01 on October 24, 2014, 09:33:08 pmhttp://www.ebay.com/itm/For-HTC-Desire-G5-G7-A8181-Nexus-One-Sony-Version-Replacement-LCD-Display-Screen-/141396027208sucker
connect drone motors to each channel of the oscilloscope - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: February 25, 2018, 02:43:36 am
content: forgive my English, for example if I have a 4-channel oscilloscope and a drone, I can place a probe to each motor and see it on the oscilloscope, or because of the dread of the mass in common can not be done, I wonder why the rigol ds1054z it has masses and earth, all connected together. and I would like to see each engine in each channel.

author: TK
author_rank: Super Contributor
timestamp: February 25, 2018, 02:47:05 am
content: You need one differential probe connected to each channel of the DS1054Z to be able to do floating measurements.From Tektronix: A floating measurement reads the voltage between two points, neither of which is at ground potentialMicsig manufactures the DP10013 differential probe that sells for around $170 each in the US.https://www.eevblog.com/forum/testgear/new-low-cost-($170)-100mhz-differential-scope-probe-from-micsig/msg1254420/#msg1254420

author: ivaylo
author_rank: Frequent Contributor
timestamp: February 25, 2018, 07:43:18 am
content: Depends on the drone. Mine uses three phase motors in a delta configuration. So a four channel scope is only good to observe one motor (unless you pick a random phase for each motor and watch all four). What are you trying to see, just RPM? If I connect the ground of my scope to the negative battery terminal of the drone and three of the channels to the three phases I get the attached picture. Again, three phases in delta configuration, so these are not the voltages which the motor sees, but what they are relative to ground. Watch your fingers...

author: paulca
author_rank: Super Contributor
timestamp: February 25, 2018, 09:01:09 am
content: If you are testing the flight controller response to gyro movements you would be better scoping the signal wire to the ESCs. They will be commoned on the receiver or flight control board. Should be a PWM signal around 50Hz, the duty cycle will reveal the motor power setting.However, I am from the old school when you had to build your own stuff from a frame, individual ESCs and motors.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: February 25, 2018, 09:41:35 pm
content: Ok, then I can connect each probe to each Motor Speed Regulator Control, so connect the four negative ones to a single point of take, the probe tips to each motor, if I did that goodbye oscilloscope? or I understood wrong, a mass in common and there if I can connect the tips to each engine. motor?

author: jomykenny
author_rank: Newbie
timestamp: November 28, 2018, 10:06:21 am
content: Quote from: Adrian_Arg. on February 25, 2018, 02:43:36 amYou can see the articles herehttps://thedroneracing.com/build-a-drone-kit/to choose for yourself a good motor
Connect heatsink to mains earth or isolated ground (transformer)  - Page 1
Forum section: electronics / beginners

author: Spikee
author_rank: Frequent Contributor
timestamp: November 17, 2012, 05:12:30 pm
content: I'm currently building a constant current load an i use a big fan assisted tunnel heatsink.My power resistor (100w TO247) and my mosfet (TO220) are both isolated from the heatsink. ( mica plates and plastic washers).I use an transformer to power my project so it is isolated. My case is aluminum and is grounded to mains earth.Now i'm not sure if i need to connect the heatsink to mains earth or the ground plane on my PCB.Any advice ?ThanksSpikee

author: SeanB
author_rank: Super Contributor
timestamp: November 17, 2012, 05:16:24 pm
content: If the heatsink is touchable from the outside then ground it to the case. Grounding it to the load side will increase capacitance to ground, so ground it to the case anyway, then the only capacitance is the power device tabs.

author: Spikee
author_rank: Frequent Contributor
timestamp: November 17, 2012, 05:22:22 pm
content: the heatsink is not touchable from the outside. Thanks for the information!
Connect multiple bluetooth device on one computer - Page 1
Forum section: electronics / beginners

author: Naxmouk
author_rank: Newbie
timestamp: June 12, 2020, 01:52:49 pm
content: Hello every one !I have a project where one sensor is connected to an Arduino Uno, then a HC-05 (module bluetooth) send the data to a computer. The computer has no bluetooth, to solve this problem I will use a USB dongle. I want to show the data of the sensor on my computer's screen so I'll use Labview to do a Human-machine interface.I know that this system can work with one HC-05, but do you know if it can work with multiple HC-05 ? Can I acquire the data of multiple HC-05 simultaneously ?If not, how can I do that ? I've been looking for information on that type of transmition (piconet) but I did not find any anwers.Thanks in advance !
Connect oscilloscope to walking talking output? - Page 1
Forum section: electronics / beginners

author: u666sa
author_rank: Frequent Contributor
timestamp: October 11, 2023, 08:12:29 am
content: Can I connect oscilloscope to output of baofeng UV-5R (with antenna attached)? I would like to measure output frequency and voltage. Oscilloscope I have is Owon HDS2202S, 200 Mhz, DMM sized portable.

author: CaptDon
author_rank: Super Contributor
timestamp: October 11, 2023, 01:03:33 pm
content: No. How will you connect 'with antenna connected'? This type of measurement is made using a known resistance dummy load with a tap on it. The load is usually 50 ohms often with a 40Db or 20Db tap. Typically you care about output power and not voltage although power can be calculated from voltage if you have a non-reactive stable known resistance. Also, your scope is not a frequency counter with a TCXO type of timebase reference. The frequency displayed on the scope will be all over the place. What is the upper frequency limit of your probes and scope? Simple answer, you will get no useful information from your scope. Chances are its frequency response at the frequencies you want to measure will be rolled off a few Db so how will you get an accurate reading of voltage? Wattmeters can be extremely broadband covering a decade or two of frequency range. Some cover a narrower range with much better absolute accuracy.

author: newbrain
author_rank: Super Contributor
timestamp: October 13, 2023, 12:31:50 pm
content: To add to CaptDon answer, there's another caveat in connecting an RF power output directly to the scope input: if you use a direct coax connection even the relatively low power of of that Baofeng might fry the scope front end.5 W correspond to about 16 Vrms or 45 Vpp, and at those frequencies (144/450 MHz) the maximum input voltage of the scope should be derated by quite a lot.Seeherefor a Tektronix example.At 20 dB per decade above 1 MHz, the max input voltage is only some volts at 150 MHz, regardless if a dummy load is used or not (and without a load who knows what the Baofeng will do).So, use an attenuator capable to withstand the Tx power with a suitable attenuation, and a 50 Ω load to terminate it (if the scope does not have 50 Ω inputs).

author: Terry Bites
author_rank: Super Contributor
timestamp: October 14, 2023, 10:00:50 am
content: You need a small coupler of some sort.A short bit of coax with a gap in the shield will do.Wear it, dont connect it to the antenna.

author: u666sa
author_rank: Frequent Contributor
timestamp: October 14, 2023, 12:09:24 pm
content: Quote from: newbrain on October 13, 2023, 12:31:50 pmPlease see my other post --https://www.eevblog.com/forum/testgear/owon-hds2202s-unrest-at-idle-state/Is this the problem I'm having right now?
Connect the dots on my schematic flasher circuit  - Page 1
Forum section: electronics / beginners

author: raspberrypi
author_rank: Frequent Contributor
timestamp: November 23, 2016, 08:05:55 am
content: This is a velman kit i built runs on 9 volts and has two adjustments that control duty cycle of led but one one is on at a time. Im trying to reverse engineer it so I'm starting small. Here is an open schematic and pics of the top and bottom.

author: raspberrypi
author_rank: Frequent Contributor
timestamp: November 23, 2016, 08:12:00 am
content: Is there a free simple schematic drawing tool? I had orcad as a kid. just something to make .jpg simple. I would even use paint to copy and past parts if I could find a good image to cut from.

author: MK14
author_rank: Super Contributor
timestamp: November 23, 2016, 08:37:20 am
content: It is a common circuit.https://en.wikipedia.org/wiki/MultivibratorOften called an Astable multivibrator.Example:EDIT: Updated circuit, as previous one looked wrong, as regards the LED resistors.

author: Zero999
author_rank: Super Contributor
timestamp: November 23, 2016, 08:40:45 am
content: The schematic is in the manual which can be found through a search engine:https://www.google.co.uk/search?q=Velleman+kit+MK102%271&ie=utf-8&oe=utf-8&client=firefox-b&safe=active&gfe_rd=cr&ei=cFU1WOfdILGn8wezsrWQDA#safe=active&q=Velleman+kit+MK102http://www.velleman.eu/downloads/0/minikits/manuals/manual_mk102.pdfThe original kit uses NPN transistors. If you want to use PNP, then you'll not only need to reverse the polarity of the battery and the LEDs but the capacitors too.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: November 24, 2016, 01:28:20 am
content: And if you want to draw schematics, you might as well just use a (free) circuit simulator like QUCS or LtSpice. Not only can you draw your schematic easily, but you can also see if it works.
Connect to USB device over network - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: July 24, 2018, 08:41:14 pm
content: I have a USB device that receives SCPI commands over raw socket port 9001. I can send *IDN? using Putty when connecting to localhost port 9001.I got the IP address of my Windows PC and then went to another PC on the network and tried sending to IP port 9001 and there is no connection.I went to my PC, Windows firewall and added inbound and outbound rules to open port 9001, and still no connection. I used TCP protocol.Any idea what to try next?Could this be blocked by antivirus or network security policy? For example, I am not able to execute batch files via scheduled task (I think just from or on network files, but need to check if a local file will execute on local files).

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 24, 2018, 09:09:42 pm
content: * Is the USB device bound to 127.0.0.1 or any interface? If it's on 127.0.0.1, see if you can change it in the config, use SSH forwarding or e.g.http://woshub.com/port-forwarding-in-windows/* * check this vianetstat /a /non Windows and look for something likeTCP 0.0.0.0:43921 0.0.0.0:0 LISTENING* Is your Firewall blocking 9001 incoming?

author: metrologist
author_rank: Super Contributor
timestamp: July 24, 2018, 09:50:43 pm
content: The USB device has some kind of back end software installed on the PC. I think this utility software acts as a local server that communicates via USB to the device, and the software I/O is via TCP/IP raw socket on port 9001.So something is blocking communication from one PC term program to another PC host program.

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 25, 2018, 12:21:19 am
content: What does the netstat line for port 9001 say?
Connected gold 82D 5v bluetooth chip in reverse polarity - Page 1
Forum section: electronics / beginners

author: stckscreed
author_rank: Newbie
timestamp: August 18, 2025, 04:19:34 am
content: So mistakenly I connected gold 82D 5v bluetooth chip with the 1amp charging module in reverse polarity and as expected it stopped working if there is anyway I can fix it now please tell the shop which sells these is really far away from me and I don't want to travel that much again for this... thanks

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: August 20, 2025, 07:33:55 am
content: Don't really know anything about that bluetooth module but it looks relatively simple. The 3-pin SOT23 device on the input may be an LDO or some sort of FET/BJT. You could see if it's dead and replace it, but it's likely the main MCU is dead.
Connecting 12v power supply , solar charger 14v , battery together  - Page 1
Forum section: electronics / beginners

author: MasterCATZ
author_rank: Newbie
timestamp: April 18, 2020, 10:29:48 pm
content: I run 12v air pumps for my Aquaponic system and expanding so I need a faster charger than I already havehow ever what I do have are a few Thermaltake Power Express 450W and 650W VGA Power Supply'sor even some dps-1200fb ( I do have pots for these to adjust the output voltage +- 2V)I was wondering how I could safely parallel power supplies to float the batteries @ 12v / run the load while the solar charge controller tops the batteries up to the 13.8v+ range / off loads some of the work when the sunshine'sif I used a dc-dc step up/down converter I believe this would protect the power supply from the voltage differences , but then it would either be keeping the batteries @ max voltage = no solar charging at all , or it would be undervolting the battery = no backup power availablewhat else could I do to protect the power supply from a higher return voltage ? potentially 2v difference in power sourcesor is it really as simple as just adding diodes ?https://www.instructables.com/id/SolarGrid-Hybrid-12V-System
Connecting 220v reball station in usa - Page 1
Forum section: electronics / beginners

author: matt.zepess@gmail.com
author_rank: Contributor
timestamp: September 20, 2024, 01:42:36 pm
content: Hello, I bought a Chinese rework station from a gentleman in the states already. He chopped off the European plug and connected a nema 6-20r, my idea is a simple rewire to 10-30p as I believe ohms law will save me by not allowing it to pull the full 30a. I mentioned it to my step dad and he’s worried about safety. Machine will only be plugged in and on when I’m nearby if that helps but he can’t fathom what I’m trying to do. Any tips? Machine is already fused with a replaceable 20a so I’d imagine that would work in event of failure. Any help would be appreciated.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 20, 2024, 01:52:37 pm
content: You are correct about ohms law.However your assumption that a rework station will behave according to ohms law like a simple resistor, may be incorrect, particularly if there is a switchmode power supply inside.A schematic diagram of the rework station would help clarify things, failing that, several good closeup photos of the internal circuit board.

author: Ian.M
author_rank: Super Contributor
timestamp: September 20, 2024, 02:35:00 pm
content: NEMA 10 series is depreciated, (banned for new installations since NEC 1996 edition) as they do not have a ground pin. It is likely that a rework station originally fitted with a Schuko European plug has a three wire cord and requires a ground for safety. IMHO unless it has a two wire cord, your stepdad is correct and fitting a NEMA 10-30P would be unsafe. The heater insulation of these Chinese rework stations is often questionable, so I wouldn't trust one with mains voltage heating elements and a two wire cord anyway!Its also worth noting that the max rated current for any European socket that can take a Schuko plug is 16A, so either that 20A fuse isn't original or the manufacturer bumped up the rating because they were getting nuisance fuse blowing due to inrush current.A way forward would be to refit the circuit for a properly wired NEMA 6-30 outlet if you don't have any equipment that needs the Neutral for 120V control circuits, or get a ground to the outlet somehow and fit a NEMA 14-30 outlet. Rather than fitting an over-rated plug on the appliance use a NEMA 6-30P or 14-30P to 6-20R adapter.If you cant refit the circuit with a grounded outlet (e.g. rented property), for private use you could make up an adapter with a separate ground wire which *MUST* be permanently connected to a good tested electrical ground. Don't let OSHA see it!