hybridfree/eevblog-posts huggingface dataset:
Impressions of the Yihua 939D+ / X-Tronic Model #3020-XTS - Page 1
Forum section: electronics / beginners

author: shaunakde
author_rank: Contributor
timestamp: October 20, 2020, 05:38:47 pm
content: I have been using a basic$5 solderingiron for far too long. Recently while putting together a little Altoid-tin amp for a friend, I managed to burn my desk and decided I needed a proper iron, and more importantly a stand.I earmarked up to $100 for the station, but I really didn't like the user interface of the Hakko 888D. (You have to set the temperature digit by digit etc.) Scrolling around I found a couple options on Amazon:1.Yihua 939D+ DigitalSoldering Station: Costs about $50 and seems to have all the bells and whistles I'd need (A PID loop etc) but I am unsure if the device is safe to use.2.X-Tronic Model #3020-XTS: Had never heard of this brand, but seems to be a US company with a warranty and a number I could call (although I suspect the unit itself is a white-labelled version ofthis one). Can't find any ratings like a UL listing though. Was wondering if anyone had an experience with this brand? Is it easy to find replacement tips? The company's website seems to be going through a renovation right now.The last option is the Weller WE1010NA. Although its a bit more expensive, I'd know its safe (I think) and have support. It comes with a god-awful stand that I'd want to replace down the line though. (Suggestions welcome!)Any thoughts would be appreciated.

author: bobcat2000
author_rank: Regular Contributor
timestamp: March 21, 2021, 05:43:04 pm
content: Have you gotten the Yihua 939D+?I too am looking for a new unit to replace my aging Weller and Radio Shack. I have these for like forever. I need to replace the tips but they want an arm and a leg for the tips. What a ripoff. Not a bargainI have a Radio Shack 64-2067a. I think this is 30W. I find it way too hot for me.So, I have another Radio Shack 64-2051a. This is 15W. But it is not hot enough.I have a Weller SP23L. It is 25W. This one is perfect for me.The Yihua was $40 on sale a week ago, and came with extra tips and accessories. This is a bargain!

author: bobbydazzler
author_rank: Regular Contributor
timestamp: March 22, 2021, 04:04:11 pm
content: I have a wep 926 which I think uses the same iron/tips as the 939 and I find it pretty good for the price, tips are very cheap so you don't have to worry about babying your tip like you do with a fixed output iron. Temperature control is also very useful for reducing stress on the tip - I usually set it between 320c and 350c depending on the tip I'm using and the iron can happily sit at those temps for quiet a while before you see any signs of oxidization. Any higher than 350c and the tip starts to oxidize pretty fast.My 926 is supposed to be a 60w station but it pulls over 100w from the wall when you first turn it on and it's heating up so heat up time is pretty fast.
Improvements on the board with differential signaling - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: March 19, 2021, 03:34:54 pm
content: As part of a layout I'm working on, I'm planning to use the PCA9615 IC for I2C communication, splitting the SCL/SDA signals to differnential signal pairs and using Ethernet to transmit them. I'm basing this part of my design around Sparkfun's breakout board shown in the link below. Their design seems to be what I need, but I'm trying to make improvements on it in order to minimize the space required. I was wondering what improvements you guys would suggest given first glance at this board?https://www.sparkfun.com/products/14589Here's what I've been thinking of so far:At first glance, I see that the bottom side of the board has no components. That just seems to be a waste of space, so in order to reduce the amount of space, the RJ-45 port will be on the top side while the rest of the components will be on the bottom side. That should allow more flexibility as to where to place components.Also, I plan to eliminate are the Quikk side headers and the external power header at the top. I'm only powering the IC through the Ethernet connector (schematic shows a diff. pair for power), so I don't need the extra features. Both the Differential I2C bus and the Single-Ended I2C bus will be powered at the same voltage (+5V), so I plan to tie them together to the same net (though, separate capacitors for both of them).The I2C pull-up resistors are kind of far from the IC, so they can be put closer together. What concerns me are the resistor terminations for the differential bus. Putting aside the values of the resistor (the ones used by Sparkfun seem to be different than what the datasheet suggests), they seem to be arranged in a way that doesn't really make much sense to me. There's a lot of empty space in this configuration, but does it accomplish anything like this? The trace pairs from the IC to the resistors are close together, but the distance could be made shorter by aligning all the resistors in a column. Also, going from the resistor to the RJ-45 jack, it doesn't seem to go between the trace pins even though there's enough clearance to do so. Is it safe to do so?
Improving draw current from phone when charging? - Page 1
Forum section: electronics / beginners

author: dominover
author_rank: Newbie
timestamp: February 22, 2018, 01:07:26 am
content: Short explanation:When I charge my phone via a usb charger you plug into the power point, by measuring the output voltage and draw current, it shows around 5.2 volts 1.5 Amps. So the phone is drawing around 1.5 Amps.When I used a hand cranked charger (portable charger) the output is 5.4 volts with .5 Amps draw current from the phone.So I tested the portable charger (hand cranked) and it seems that I can get as much as 5.5 volts 3 Amps from it consistently.From what I'm told, this is because the phone queries the charger and tells it how much draw current there should be. Unfortunately, the phone can't communicate with the hand cranked charger so the draw current remains low at .5 Amps.I was told to bridge the positive and negative terminals of my charger output cord with a 1000uf to 47000uf capacitor. But I'm not sure what this will do. I can't seem to find the person who told me this so I'm asking does anyone know why this would work and if there are any other solutions to my problem?Thanks

author: Rerouter
author_rank: Super Contributor
timestamp: February 22, 2018, 03:58:00 am
content: Forget adding the capacitance,What model is your phone, pretty much there are roughly 2 and a half passive signalling standards, e.g. the old apples needed there data lines held at a certain voltage

author: dominover
author_rank: Newbie
timestamp: February 22, 2018, 09:03:28 am
content: Thanks for replying.. I'm using a chinese phone called a Blackview BV6000 (it's a rugged phone) and uses a Helio P10 processor (Mediatek). Android 7.

author: paulca
author_rank: Super Contributor
timestamp: February 22, 2018, 09:32:31 am
content: Depending on the phone a shorted pair of data lines may only pull 0.2 - 0.5amps. Putting various resistances on the data lines or voltage dividers may convince it to pull more like 1 amp, maybe 1.5 amps.Modern phones use the Qualcomm QuickCharge protocol which is an IC based charge negotiation system. For example, my Motorola G5+ when plugged into a QC3.0 charger will switch up to 9V and pull 1.5Amps.Without quick charge it is not just the sensing of the resistance/voltage on the data pins which determines the charge current. The phone will sense voltage drop, so it will pull a little current and monitor the voltage, then pull a little more and as soon as it sees a voltage drop it decides that is all the charger is capable of and stops there.It is highly likely that your phone will be highly suspicious of your hand cranked charger and not want to overload what it sees as a weak charger.
Improving output from AMS1117 - Page 1
Forum section: electronics / beginners

author: soligen
author_rank: Contributor
timestamp: October 09, 2017, 08:48:53 pm
content: I have a question about getting good clean power from an AMS1117 (a Chinese clone). I have experienced some issues that might be power related (not sure).I am running a NRF24L01+ with PA/LNA and supplying 3.3V from and AMS1117. The data sheet calls for an output capacitor with ESR between .3 to 22 ohms. Instead of using a tantalum cap, I am using ceramic caps (3 paralleled 10uf) with a .6 ohm resistor in series.Since these modules are reportedly sensitive to poor power, and I had a comment that a better regulator may be in order (but I cant fins a good replacement). I have a few concerns and I would like feedback of the concerns and possible ways to address them.My first concern is that the caps on the NRF24L01 module board may lower the effective ESR below .3 ohms and cause stability issues. My second concern is that the .6 ESR I have introduced will limit the how much current the caps can give up to the module when demand suddenly goes high (when a packet is transmitted) causing a dip in voltage until the AMS1117 can correct for it. So here are my questions:1) Are my concerns unfounded?2) Would a LC filter on the regulator output be effective? My thought is that the output caps would have the correct ESR, then after the LC filter I could use very low ESR decoupling without impacting the regulator stability. I had read some posts that lead me to think LC after a regulator is a bad idea.3) How about taking power directly from the output caps after t the .6 resistor? I think load regulation would be worse with this.Here is a link to my schematichttps://github.com/soligen2010/RC_RX_CABELL_V3_FHSS/blob/master/hardware/SchematicNoDiversityNoSBUS.pngThanks

author: sleemanj
author_rank: Super Contributor
timestamp: October 09, 2017, 08:56:13 pm
content: Put a cap directly, physically, on the nrf module, across vcc and gnd. You will probably find that helps most.

author: wraper
author_rank: Unknown
timestamp: October 09, 2017, 09:07:49 pm
content: Apperently your circuit shouln't need much current. So just use cheap MLCC tolerant LDO like MIC5504-3.3YM5 or similar. And save on high capacitance MLCCs as well as it doesn't need more than 1uF.

author: soligen
author_rank: Contributor
timestamp: October 10, 2017, 03:31:21 pm
content: Thanks for the input. The MIC5504 looks good. I will order some up for my next board revision.
Improving simple filter cap tester. - Page 1
Forum section: electronics / beginners

author: JHAnd
author_rank: Contributor
timestamp: November 20, 2023, 09:25:42 pm
content: Hi,I made a simple filter cap "tester". It's just a 100uF 500V capacitance with crocodile clips for positive and negative. I use it to find 100hz buzz from bad filter caps, paralleling one cap at a time until the buzz goes away... then I have found the bad cap that needs replacing.When done I discharge the "tester" through a resistor.I usually have the amp on while testing and change the positive lead from cap to cap. Each time I clip the positive lead to a cap I get a tiny arc.Is there a way to not have this happen? I find it startles/scares me even though I know it is going to happen.Would paralleling a resistor work?

author: iMo
author_rank: Super Contributor
timestamp: November 20, 2023, 10:09:00 pm
content: Yes, that is the standard way people do it.The value should be large enough not to affect your measurement, and its time constant RC low enough to discharge the capacitor fast enough. So you have to find a compromise with the resistor value.Also the voltage/power rating of the resistor is important provided you operate it at large voltages.

author: shapirus
author_rank: Super Contributor
timestamp: November 20, 2023, 10:38:14 pm
content: I'd wire it up in some primitive enclosure with two buttons like this:

author: MarkT
author_rank: Frequent Contributor
timestamp: November 22, 2023, 07:17:30 pm
content: Power down before connecting it or disconnecting it, then you won't have any arcs. Also this greatly reduces chance of fumble-induced shorts which can be expensive if something blows up - yes its a lot slower, but you have peace of mind.Recommend wearing eye protection when working with significant stored energy in electrolytics.

author: Vovk_Z
author_rank: Super Contributor
timestamp: November 23, 2023, 08:31:32 pm
content: Quote from: JHAnd on November 20, 2023, 09:25:42 pmVoltages about 200VDC and higher tend to create small arcs. It even can be seen just when you are measuring voltage with some DMMs.
Impulse wall socket power supply typical schematic and upgrade - Page 1
Forum section: electronics / beginners

author: 001
author_rank: Super Contributor
timestamp: October 24, 2017, 12:22:17 am
content: Hi! Nubie question from oldschool electricanI have wery unstable mains (random voltage from 180 to 230V) and I`m looking now for bunch of impulse power supplies (9)12V 2A with wide input range(See varians in attachments)What about typical schematics, ripple voltage, hum etc.? Can I tweak this unit to other output voltage without rewinding transformer?Thanks!PS: Sorry for my english

author: ebclr
author_rank: Super Contributor
timestamp: October 27, 2017, 12:04:52 am
content: Tipically this is inside those box
IMU for rocketry - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: January 18, 2025, 01:49:17 am
content: Friend is looking for something much better than the old MCU-6050.I thought this might be good but not finding a lot of popular options. Any suggestions?https://www.pololu.com/product/2862

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: January 18, 2025, 04:18:00 pm
content: I'm a fan on ST's LSM6DS line of IMUs like the one on this Pololu module. They have good functionality and pretty much "just work". Their accuracy isfarbetter than that of the MPU-6050. If your friend only needs one to detect free-fall for parachute deployment, they even have a built-in function for that so he wouldn't need to write code to do the processing. Of course he can stream data off and do Kalman filtering or whatever just like with any other IMU. What they donothave is the MPU-6050's DMP (but the DMP was notoriously difficult to get working well).Also, assuming (by the MPU-6050) that your friend's using Arduino, there appears to be decent Arduino support for the LSM6DS.Plus the price is right (I mean of the chip itself ... the module is a bit expensive, but Pololu are worth supporting, they do good work).

author: bobev
author_rank: Newbie
timestamp: January 20, 2025, 11:14:22 pm
content: The rocketry team I'm on uses the BNO086. It seems like it's not that uncommon a choice looking at boards fromother teams, although it may be overkill for your friend's application.If I remember correctly we also use the BNO055 which has on-board sensor fusion capabilities. Looking online some other folksrecommend the ICM-20649as well as it has a large range in terms of the Gs it can tolerate, and is also a bit more reasonably priced. Adafruit has boards for the BNO055 and ICM-20649, and Sparkfun has one for the BNO086 if any of them seem like interesting options.

author: metrologist
author_rank: Super Contributor
timestamp: January 20, 2025, 11:20:53 pm
content: Cool - he was also looking at BMI088.Using ESP32 and they plan on controlling the fins.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: January 23, 2025, 06:39:41 pm
content: You can go for Bosch BNO055 or InvenSense ICM-20948.
IMU from China - Page 1
Forum section: electronics / beginners

author: mr_byte31
author_rank: Regular Contributor
timestamp: January 11, 2025, 03:48:55 pm
content: Hi,I have purchased several 9-axis IMU modules from Aliexpress. I tried GY-91 (contains MPU9250) and GY-912(contains ICM20948).All the modules had fake IMUs --> they don't contain the magnetometer.I was thinking to use Jlcpcb or Pcbway to assemble a new board that I am designing. this will relief me from the hard soldering nightmare of the IMUs and Baro. the board shall contain ICM20948did anyone try the IMUs of Jlcpcb or Pcbway and can confirm they are genuine parts ?
IMU - PCB Design - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: April 13, 2019, 08:05:21 pm
content: HelloI wanted to use an LSM9DS1 on my PCB but there is no PCB design recommendation in the datasheet.To make the magnetometer work in a reliable way, should I remove the ground plane, on all layers of the PCB, under and surrounding the chip or is it not necessary???Thank you
IMU sensors + Wifi  - Page 1
Forum section: electronics / beginners

author: VoltaCH
author_rank: Newbie
timestamp: May 23, 2019, 09:20:05 am
content: Hello,I need to design a system where an IMU sends data by wifi to a central system ( to be chosen too).For example I would think of an IMU sensor that is connected to raspberry zero. The raspberry zero sends the data by wifi to the central system which would be a raspberry pi B for example. The idea is to have many of these IMU sensors send data by wifi to the central system.All i need from the IMU is the attitude ( orientation ) and the acceleration or velocity.My questions are :1 - Which good IMU would your recommand? and how do you do a benchmark for a sensor in general ( finding suppliers- by just googling it ?) ??2 - What would you choose to send IMU measurements by WIFI ? an embedded system ( which one ) ? an arduino ( not very professional ) ?3 - what would you choose as a central system ?Thank you very much
iMX6ULL board not booting troubleshoot - Page 1
Forum section: electronics / beginners

author: datasheet
author_rank: Newbie
timestamp: May 21, 2023, 07:49:08 pm
content: I asked a few months ago for a review for a SBC I made based on the MX6ULL processor:Fast-forward to today, I ordered the board, assembled it, and begun testing.Things I know work:- All voltage rails: 3V3, 1V8, 1V375. Ripple is minimal.- Power sequencing is done correctly.Things that don't work:- The processor doesn't appear to boot.- The serial downloader device doesn't appear when USB_OTG1 is connected to a computer.- The serial downloader in UART mode also fails.- I fucked up and didn't mux UART1 to the default position, I didn't fan out boot straps that would eventually have allowed me to boot from eMMC, nor the SD1_CD pin which allowed Manufacture Mode to work.Other remarks:- The current draw on power up is 200 mA @ 5V. The processor fairly hot (40-45°C) considering it's supposedly doing essentially nothing (busy waiting in the boot ROM at a low frequency). Not sure what to make of that,is it normal?- The 24 MHz crystal doesn't seem to work, at all. I probed the XTALO pin in 10X mode and see either nothing, or noise. I probed the Ethernet PHY 25 MHz crystal in the same way and I got a meaningful result. That would explain the serial downloader not working. But why would the crystal not work? There's no way it was overheated, the pins are correct, the load capacitors are correct and it's connected to the right balls.Possible issues with the 24 MHz crystal:- The maximum drive strength for the crystal I used is 100µW compared to the required 250µW. However the Ethernet PHY requires 300µW and still appears to work with a 100µW one.- No ground keepout under the crystal unlike the Ethernet PHY's.- I badly soldered the processor, but I think that's unlikely considering it's a 0.8mm BGA.None of these appear significant, or likely. Are there other reasons I could have missed? Is there other tests that would help me sort the fact that's it's not booting?I attached a screenshot of the crystal layout and the signal I get when probing the 25 MHz crystal. I also attached the schematics.
In-14 nixie current limiting resister  - Page 1
Forum section: electronics / beginners

author: Aztlanpz
author_rank: Regular Contributor
timestamp: December 29, 2015, 07:43:54 pm
content: How do I calculate the current limiting resistor for a nixie IN-14 at a voltage of 150v?Thanksaztlan

author: retrolefty
author_rank: Super Contributor
timestamp: December 29, 2015, 08:11:16 pm
content: Quote from: Aztlanpz on December 29, 2015, 07:43:54 pmWell if you want to try for yourself here is a link to a datasheet. Just apply Ohm's law.http://tubehobby.com/datasheets/in14.pdf
in a fight with audio amp sharing power supply - Page 1
Forum section: electronics / beginners

author: shoebones
author_rank: Newbie
timestamp: June 20, 2023, 02:11:25 pm
content: I'm trying to amplify the output of some bluetooth headphones using an LM386 board. when the amp and headphones are on different power supplies, the audio is amplified. but when the 2 share a power supply, no audio is produced. when they share a power supply, both components are working. the amp is amplifying an aux signal, and the headphones output audio to a speaker. just quietly without the amplification. I'm not sure what's causing this, and hoping to get a better understanding and hopefully find a way to make it work without needing 2 power supplies. thanks!

author: Terry Bites
author_rank: Super Contributor
timestamp: June 20, 2023, 02:55:49 pm
content: Dig out your DMMWhat is the external power for the LM386 PCB, how many volts?Check the bluetooth power supply. How many volts are there when nothing else is connected?What happens to BT's positive power rail when you connect your amp?Is your LM386 V+ shorting to bluetooth ground?Bluetooth devcies often operate on 3.3VCan the bluetooth circuit supply the current and voltage requirements of the LM386 amp4V minimum 4mA quiescent.The bluetooth amp maybe detecting an error condition on its outputs and shutting down.Are they floating or ground referenced outputs?

author: shoebones
author_rank: Newbie
timestamp: June 20, 2023, 03:28:43 pm
content: thanks for the reply.the lm386 is receiving 5vthe headphones run on a 4.2v lipo, but seem to operate without issue at 5vi'm now thinking it is something to do with the amp, which reads a short between v+ and ground when it's powered on, and since it's sharing the power supply with the bluetooth device the headphone ground is shorted with the amp's v+I'm testing with a 5v 1a power supply, which should be plenty to supply both. while power was provided I tested the amp and headphones separately and they were both working.I'm working on a way to test if the amp is erroring
In a Parallel Resonance circuit (C parallel with RL) - Page 1
Forum section: electronics / beginners

author: sspj9
author_rank: Contributor
timestamp: May 10, 2016, 08:13:56 pm
content: Why does the total supply current increase when the capacitance value is further increased after parallel resonance is reached (where the supply current is minimum) ? I know it has to do with the phase angles but I cannot reason it out.Thanks

author: Ice-Tea
author_rank: Super Contributor
timestamp: May 10, 2016, 08:17:12 pm
content: The resonance occurs for a frequency defined by the L and C. So if you change the C, the frequency changes. Or at the same frequency, you are no longer at the resonance frequency

author: sspj9
author_rank: Contributor
timestamp: May 10, 2016, 09:05:35 pm
content: What does the frequency has to do with the supply current though?

author: rstofer
author_rank: Super Contributor
timestamp: May 10, 2016, 09:12:03 pm
content: http://www.electronics-tutorials.ws/accircuits/parallel-resonance.htmlThe impedance of a parallel resonant circuit is highest at resonance - thus the lowest current. The impedance decreases on both sides of resonance - thus a higher current.The linked page gives a very good discussion of parallel resonant circuits and their analysis.

author: danadak
author_rank: Super Contributor
timestamp: May 10, 2016, 09:19:22 pm
content: A pure LC resonant parallel tank at resonance exhibits an infiniteimpedance, no matter what the values of L and C, for finite valuesof L and C. Therefore no current is drawn by the tank, the energysimply cycles back and forth between the reactive elements, L & C.If there is a finite R in parallel with L & C, then the tank exhibits Ras its resonant impedance value.https://en.wikipedia.org/wiki/LC_circuitRegards, Dana.

author: rstofer
author_rank: Super Contributor
timestamp: May 10, 2016, 09:50:46 pm
content: Perhaps a more intuitive way to look at it is to just consider the reactances in parallel.For the inductor, the reactance is Xl = wL where w is omega - 2 pi f. We can see that the reactance increases with increasing frequency. Conversely, the reactance decreases with decreasing frequency. For the parallel circuit operating below resonance, the inductive reactance dominates the circuit.For the capacitor, the reactance Xc = 1/wC so the reactance decreases with increasing frequency and increases with decreasing frequency. For the parallel circuit operating above resonance, the capacitive reactance dominates the circuit.In either case, the farther the circuit is from resonance, the lower the overall impedance and the higher the current flow.Pick a really big number for w: Xl will also be a big number and Xc will be a small number. For a big number, the capacitor dominates the parallel combination.Pick a really small number for w: Xl will also be a small number and Xc will be a large number. For a small number, the inductor dominates the parallel combination.

author: w2aew
author_rank: Super Contributor
timestamp: May 10, 2016, 10:04:20 pm
content: Here's a video I did on LC resonant circuits, just in case you were interested:
In AC analysis, do people replace large inductors - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: November 02, 2022, 02:42:47 am
content: For small signal AC analysis with phasors, and caps, people routinely ignore the low value impedance of bypass caps, and just pretend they are a short. But with a large blocking inductors, I guess I've never worked out those circuits circuits enough, so I'm wondering if people would replace a relatively large impedance inductor with an open circuit ?So like in an AC small signal analysis of some RF amp with an RF blocking inductor, if it's impedance is way bigger than anything else, do people replace it with an open circuit in the models for a given frequency?

author: TimFox
author_rank: Super Contributor
timestamp: November 02, 2022, 03:31:51 am
content: You can replace a large "choke" with an open-circuit for an early analysis, but it is not a good idea to ignore the finite reactance for a detailed analysis.In RF, they are usually called "RFCs", for radio-frequency choke.In a typical RF circuit, you may find the reactances of an RFC and a bypass capacitor in parallel, and you could get an unwanted resonance if you ignore them.In Spice, the DC operating point is found by open-circuiting all capacitors and short-circuiting all inductors, but that's a different calculation.

author: EPAIII
author_rank: Super Contributor
timestamp: November 02, 2022, 04:20:57 am
content: I fear the answers to such a question are both Yes and No. The trick is knowing when each of those applies.
in-amp or transducer drift - Page 1
Forum section: electronics / beginners

author: V_King
author_rank: Regular Contributor
timestamp: January 15, 2014, 01:56:03 pm
content: Hello,I am using AD623 instrumentation amplifier for the load cell output signal conditioning.The signal is constantly drifting by a very small amount, which makes hard to set reference values for the calculations in the software.Firstly I was assuming that the temperature is the only cause, as it makes the biggest difference in the readings. But even keeping the load cell constant temperature I get a drift.One friend, who has more experience with electronics suggested that that might be due to the fact that I am using single supply for the AD623 in-amp.I wonder if swapping to the dual supply and even swaping in amp to AD620 help if not to solve, at least to reduce the drift problem? I used the reference circuit from AD623, datasheet p.17, fig45 for the circuit.Cheers

author: Odysseus
author_rank: Regular Contributor
timestamp: January 16, 2014, 02:59:12 am
content: How much is it drifting by, and how much gain have you configured the circuit for (i.e. what is the value of Rg)?I ask because it may simply be due to the noise generated by the chip itself. Table 3 on page 6 and figure 10 and 13 on page 9 contain some relevant information. For example, if your amplifier is configured for a gain of 1000, then according to the table, the low frequency 0.1-10Hz RTI noise is 1.5uVpp. Thus the output referred noise will 1000x this, i.e. 1.5mVpp of drift.

author: qno
author_rank: Frequent Contributor
timestamp: January 16, 2014, 10:40:06 am
content: Be shure about temperature.I have seen drift due to a connector near a voltage regulator.One side of the connector was a tiny bit warmer than the other side.Removing the voltage regulator solved the problem.A thermocouple effect can have big influence with a gain of 1000.

author: V_King
author_rank: Regular Contributor
timestamp: January 19, 2014, 01:15:42 pm
content: thanks for answers.the load cell has an internal pre-amplifier to the output of 0-5V and load cell manufacturer supplied the power supply as well. I am just using the ad623 at the other end as a buffer and to reduce common noise at a unity gain, as the cable is 4m long (shielded) and the load cell is in noisy environment.the drift is around 20mV/hour, which corresponds to 10kg in the load cell and is 10 times larger than the load cell specs, so I presume there is space for improvement. I made some rough compensation for the drift and it sort of works as the load cell is used max 10-15 min at a tme, but the engineers curiosity keeps me coming back to look for improvements

author: tszaboo
author_rank: Super Contributor
timestamp: January 20, 2014, 12:05:01 am
content: Do you have a bias current path? Is the transducer floating?
In Common emitter Circuit - higher amplification - Page 1
Forum section: electronics / beginners

author: ulix
author_rank: Regular Contributor
timestamp: December 20, 2015, 11:37:24 pm
content: Hi,I was just wondering, which transitor npn or pnp has a higher amplification in the common emitter circuit?I would say, it's the npn type, but how can I prove this?cheers

author: langwadt
author_rank: Super Contributor
timestamp: December 21, 2015, 12:04:19 am
content: Quote from: ulix on December 20, 2015, 11:37:24 pmwhy would the amplification be different just because you flip it upside down?

author: ulix
author_rank: Regular Contributor
timestamp: December 21, 2015, 12:12:28 am
content: npn to pnp doesn't mean flipping!? it's a diffrent transitor.

author: Marco
author_rank: Super Contributor
timestamp: December 21, 2015, 12:26:33 am
content: If it's degenerated sufficiently the amplification depends on the ratio of the emitter and collector resistors.If it's not degenerated and at sufficiently low frequencies the AC amplification is purely a function of biasing, it is independent of NPN/PNP or even device material. This is because gm is purely a function of Ic, see page 24 ofthis class handout. I did not know this part before googling.PS. the only time I see non degenerated common emitter amplifiers is in RF circuits.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 21, 2015, 12:29:50 am
content: Quote from: ulix on December 21, 2015, 12:12:28 amIf it was 1964,the standard answer would be "an NPN",but,over the years,PNPs have improved,due to better manufacturing processes,till there is no real difference.There are still more NPNs around,though.

author: dom0
author_rank: Super Contributor
timestamp: December 21, 2015, 12:39:53 am
content: The fundamental difference between hole and electron mobility is still there, and a few in-silicon processes are different, too. So you still don't get identical transistors just by flipping N and P.That being said the common emitter circuit will behave similar for transistors with similar key specs (fT, miller capacitance, beta), independent of NPN or PNP. Of course, finding RF PNPs tends to be not as easy as coming up with a NPN.QuoteCorrect. Although, as you mention, too, it is only true for low frequencies, where the Miller effect may be neglected. However, the equation Rbe = Ut / Ic is still a very important one in many fields, e.g. linear supply design, AF amplifiers etc. and often disregarded (with corresponding, i.e. bad, results).

author: ulix
author_rank: Regular Contributor
timestamp: December 21, 2015, 12:58:02 am
content: Both should have the same dimensions...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 21, 2015, 02:28:30 pm
content: Complementary PNP are about 10% worse (mainly as hfe with respect to frequency, and Vce(sat)), but this is much less than the >40% difference in a single part (regardless NPN or PNP) due to manufacture and temperature variations. If your circuit will fail due to this difference, it's a textbook Bad Circuit.Tim
In LTSpice, how can an unconnected source affect rest of sim ?? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: July 03, 2025, 03:47:08 pm
content: I'm running a .tran sim, and there's a ramp voltage, not connected to anything besides GND and a labelled node. Yet a bunch of places in another circuit, vary slightly over the 11 second sim, all with a visual slope that matches the 0-5V slope of the ramp. And they stop changing when the Vramp stops.I've seen this effect in LTSpice before, were seemingly unconnected sources, besides GND, changes the rest of some circuits.So what is LTS doing ? In this case, a 437mA current from mosfets, changes by ~90nA, due to this unconnected Vramp. And a 21uA current changes by ~6pA. And similar for just about everything else.

author: iMo
author_rank: Super Contributor
timestamp: July 03, 2025, 05:40:29 pm
content: It seems LTS simply connects all free hanging nodes together via a "large resistances like XXXGohm" in order to create the set of equations (and the related matrices). I saw it in past too..PS: I posted an example perhaps a month back - the "capacitive DC divider"..https://www.eevblog.com/forum/projects/infinite-input-impedance-voltage-measure-circuit/msg5934730/#msg5934730

author: MathWizard
author_rank: Super Contributor
timestamp: July 03, 2025, 06:03:14 pm
content: I'm sure I ran the sim after labelling the Vramp, K1, but when I went back at LTS, it crashed and closed. And now it's not doing it.

author: iMo
author_rank: Super Contributor
timestamp: July 03, 2025, 06:16:27 pm
content: Labeling plays no role, imho. When you draw a wire it gets an internal name immediately. Your label just changes that name.LTS has got some strategy on handling the "free hanging nodes/wires", would be great to know details, indeed..

author: MathWizard
author_rank: Super Contributor
timestamp: July 03, 2025, 06:20:32 pm
content: Well I definitely ran the sim after labelling the node, it won't click on it or display it in the plot w/o running 1st. And then I had done some more adjusting and running, before it crashed. It doesn't crash often, and this circuit sim run pretty fast and I think that was the 1st and only crash.

author: Zero999
author_rank: Super Contributor
timestamp: July 03, 2025, 06:51:30 pm
content: We don't know whether any of those nodes are connected to anything, because you forgot to post the .asc file.
In Over My Head... Is this going to explode? - Page 1
Forum section: electronics / beginners

author: RocketCat20
author_rank: Newbie
timestamp: March 21, 2019, 01:04:38 am
content: I have the circuit described in the images attached. Please ask any questions you have. I just want to know if this circuit looks problematic to anyone. The LED includes a resistor and can handle the 24V. Thanks!

author: coppercone2
author_rank: Super Contributor
timestamp: March 21, 2019, 01:13:05 am
content: put a fuse

author: RocketCat20
author_rank: Newbie
timestamp: March 21, 2019, 01:15:20 am
content: Quote from: coppercone2 on March 21, 2019, 01:13:05 amWhere and how big?

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: March 21, 2019, 03:32:46 am
content: Fuse the wire connected to the positive battery terminal, as close as possible to the battery terminal. This is purely to protect the wiring from a possible short circuit.Fuse rating is based on the ampacity of the wire used, if not sure look up AWG ampacity table for reference. You don't have to fuse to the maximum ampacity of your wiring, eg; your wiring can supply 30A, but your circuit will never draw more than 5 amps during normal use - I would use a 7.5 or 10 amp fuse.

author: coppercone2
author_rank: Super Contributor
timestamp: March 21, 2019, 04:20:20 am
content: read the littlefuse documentation to get a more clear idea of how fuses work. it can get rather complicated to specify them optimally. the jist of it depends on inrush current, peak current/sustained current and life time of the fuse (you can theoretically specify a fuse to only work for 100 power up cycles for instance, but the tollerances of a fuse are probobly pretty large compared to numbers you normally associate with electronics). The more you overrate (assuming its not a specialty fuse like slow, medium, time delay, etc) the more cycles you can get from it, but the less optimal the protection it offers will be.

author: mikerj
author_rank: Super Contributor
timestamp: March 21, 2019, 08:43:49 am
content: You have your 5v Arduino supply connected directly across an ammeter, so smoke and flames are a definite possibility.
In search for a 5s Li-ion battery balancing chip - Page 1
Forum section: electronics / beginners

author: m.k
author_rank: Newbie
timestamp: February 06, 2017, 08:02:09 pm
content: Hey guys, as this is my first appearance in this forum, I think I should probably introduce myself a little. My name is Michael i am 23 years old and i guess you would call someone like me college student. I'm an Austrian and studying in Germany at the moment (more like mechanical engineering so my lacking electronic skills are not as embarrassing). I've been watching eevblog for years, and now i have a question.Background of this project is: I want to build a tool battery. For the DeWalt XR system. Yes I totally know one can buy one for 40 bucks, but hey I guess I'm not the only insane person here, right? With the XR system no switching is done in the battery. Overvoltage is taken care by the charger, Overtemp by the tool and the charger. Undervoltage protection is built in in low drain tools, with high drain you change out the battery before the voltage gets too low. No parasitic resistance where it's not needed.Leaves balancing. In original DeWalt packs there is a balancing (or equalizing?) IC which is active all the time i guess. I don't know if the charger does balance the cells. It does have a connection to each cell but hey, there is balancing going on in the pack so I am not sure. I did disassemble the charger to see if a balancing chip is used but the PCB is glued in tightly and i was afraid to break it. The information to come to this conclusion is drawn from a very good and usefulblog articleof someone disassembling his battery pack. Mine is - you guessed it - gooped all over so you can't see a thing from the PCB.source:https://syonyk.blogspot.de/2016/09/dewalt-20v-max-30ah-battery-pack.htmlTo build my own battery I'm now searching for such an chip used in the original pack, which just does balancing (or is that called equalizing?) and none of the whole protection stuff. Chips i found either do balancing and protection and are therefore huge (like huge amounts of pins) or even need external transistors which lets this little project get quite complicated. Buying a typical chinese protection board from ebay is a consideration, but in fact they are kinda big and i would have to hack it to just do balancing. And they are not thaat dirt cheap for probably not even a genuine chip and using just a fraction of the capability.I thought maybe someone here has worked with such a device in the past and wants to share.(As it will most certainly be a SMD device this would be my first attemt at a PCB. Oh boy)

author: m.k
author_rank: Newbie
timestamp: March 26, 2017, 02:48:56 pm
content: Okaay, i recently picked the project up again and if someone comes across this and want to know how i did it, well i did nothing. The Charger did balance the battery in a little measurment i made today and if the selfmade battery works out i will measure the cell voltages now and then to see if the balancing from the charger is sufficient.
in series vs parallel - Page 1
Forum section: electronics / beginners

author: Irilia
author_rank: Regular Contributor
timestamp: September 05, 2024, 10:14:20 am
content: My brain got mixedCan I combine for example a power source of :30 A+20 A to get 50 AOr70 V + 30 V to get 100VIf my memory is right the smallest of the two power source will be overwork.

author: Laval
author_rank: Regular Contributor
timestamp: September 05, 2024, 10:24:54 am
content: If you combine sources in series, you will add voltages. If you combine sources in parallel, assuming they have the same voltage, you will add current. That works with batteries for example. But combining random source together, including batteries, can cause problems in practice. Power supply generally don't work well in parallel, unless they have been designed for that, because their regulation feedback loops may interfere with each other.It would help to have a bit more context to answer your question.

author: Phil1977
author_rank: Frequent Contributor
timestamp: September 05, 2024, 10:25:02 am
content: In general: Yes.You can switch two PS with similar voltage in parallel and get their summed up amperage.You can switch two PS with similar max. current in series and get their summed up voltage.But this is only valid for galvanically isolated and current limited supplies. It´s okay (and common use) to do this with laboratory power supplies, but it´s dangerous with nearly everything else.

author: Irilia
author_rank: Regular Contributor
timestamp: September 05, 2024, 10:44:02 am
content: Ok so I will do that both of the power source identical, so problem solved 😉Thanks for your answers.
ADAU1701 alternatives for simple audio DSP project? - Page 1
Forum section: electronics / beginners

author: danieljfarrell
author_rank: Contributor
timestamp: June 28, 2022, 06:47:03 am
content: HelloI would like to play around with audio DSP by making an FIR filter.I know that the ADAU1701https://www.analog.com/en/products/adau1701.htmlcan do what I need, but it is hard to get.Maybe TI's TAS3204https://www.ti.com/product/TAS3204is a good alternative?In terms of device specifications, I am unsure what I need. The impulse response I will use is: momo, 24 bit, 48kHz sample rate (truncate to 984 samples) and the ADAU1701 can handle this.What specifications should I look for in finding an alternative?Thanks!

author: Marco
author_rank: Super Contributor
timestamp: June 28, 2022, 10:28:30 pm
content: Any old Cortex M7 with an i2s codec is plenty powerful. What sets the ADAU1701 apart is that it doesn't require any programming, you can't for instance make a FIR filter with it. You can give it a small set of FIR filter coefficients and it will do it, but you're not the one making the FIR filter program.The Teensy I think has the biggest hobbyist community programming audio DSP not on PCs (lots of DSP plugin development for PCs obviously). There's also the Bela DSP, which can do thousands of taps of straight FIR filtering. Don't think anyone implemented zero latency FFT based filtering yet unfortunately, so if you want multisecond reverb or room correction you'll have to implement that yourself ... the ADAU obviously ain't going to do it either though.Everything which is not ADAU requires more programming though.

author: danieljfarrell
author_rank: Contributor
timestamp: June 29, 2022, 06:39:44 am
content: Thanks!That’s really helpful to get the big picture.The problem is availability of micros, but it’s good to know that this is not really a computational difficult problem and can be handled by even old hardware.So the ADAU seems a good route or the Teensy if I want to do the programming myself. I will contact the Bela folks too.ThanksDan
IN4152 signal diode equivalents? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 26, 2014, 11:40:17 am
content: Details of circuit here:http://www.w1vd.com/137-500Phasingexciter.htmlSchematic here:http://www.w1vd.com/Phasingexciter.pdfI am only constructing the RF amp from U7A and beyond. I am unable to find any IN4152 signal diodes here in the UK, can someone more knowlegabler than I suggest a more commonly available equivalent please?I have found the data sheet for these and similar signal diodes, to save effort I have it at:http://www.gatesgarth.com/IN4152.pdfif it doesn't attach below. Many thanks

author: SeanB
author_rank: Super Contributor
timestamp: December 26, 2014, 11:54:53 am
content: Nothing exotic ablout these, replace with a regular 1N4148 or 1N914, no problems. Just keep them close to the 2 transistors ( preferably touching cases) so they are able to be close in temperature, as they are there to bias it into class B operation.
IN4936 fast recovery diode substitutes? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 11, 2014, 02:03:18 pm
content: Here in the UK it seems I cannot find 4 off IN4936 fast recovery diodes for a project. Is there a more available equivalent please?http://www.alldatasheet.com/datasheet-pdf/pdf/209710/FCI/IN4936.html

author: oldway
author_rank: Super Contributor
timestamp: November 11, 2014, 03:05:17 pm
content: UF4007

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 11, 2014, 08:41:29 pm
content: Quote from: oldway on November 11, 2014, 03:05:17 pmOK, many thanks, I believe I *may* have found the actual IN4936's . A friend is checking his shack! Cheers oldway

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 12, 2014, 04:28:59 am
content: Probably something from the PR100x or FR10x series would be even closer. UF400x are actually pretty fast (less than half the reverse recovery time), but that's probably only ever a good thing.Tim
INA 219 current sensing maximum wattage - Page 1
Forum section: electronics / beginners

author: lots o tots
author_rank: Contributor
timestamp: April 27, 2018, 03:08:14 am
content: I have an INA 219 and want to calculate the current, but i dont know if it is too high for the INA219.https://www.adafruit.com/product/904According to the specs it can monitor at up 26V and up to 3.2A. the current sense resistor is 2W.The voltage in the circuit will be 19.5V. i wanted to be able to run current through this at up to 3A. exact current value is unknown at the moment. The load will probably be 50% to 75% duty cycle.Does the current sense resistor at 2W mean that if i run at 19.5V, i cant sense more than 0.1A without burning the sense resistor? (0.1A x 19.5V = 1.95W).if i cant monitor anything past 1.95W, i will have to use a low value load only through the resistor like a small LED and just add a correction factor to the real load. i dont really want to do that if it can be avoided. Is there something that i can wire into the circuit that has a precise load that will provide a constant voltage, constant current that the INA219 can safely sense. Also(there will actually be 2 seperate circuits and i want the loads in those 2 circuits to be as close as possible to each other.)thanks-LOT

author: paulca
author_rank: Super Contributor
timestamp: April 27, 2018, 07:14:25 am
content: To work out the maximum through the resistor you need to know it's value. It will drop a certain voltage (used to sense the current) for a given current. Multiple that voltage by the current to get the power dissipated by the resistor.So if it's a 0.1Ohm resistor at 3.2A it will drop 320mV. That is 3.2*320mV ~= 1W. You might note you can just do Current2Amps * Resistance Ohms = Power Watts dissipatedOhms law.

author: lots o tots
author_rank: Contributor
timestamp: April 27, 2018, 01:08:30 pm
content: I see, so we muliply the current by the voltage drop and not the voltage for the voltage in the circuit, as the rating is for the heat it can dissipate.interestingThanks