hybridfree/eevblog-posts huggingface dataset:
Vortex Coils, wire size and coil forms  - Page 1
Forum section: electronics / beginners

author: maheanuu
author_rank: Newbie
timestamp: October 21, 2014, 08:59:43 pm
content: I am very interested in winding and using vortex coils. I would also like to know if they are wound in the same direction in the southern hemisphere as in the northern.

author: Hideki
author_rank: Frequent Contributor
timestamp: October 21, 2014, 09:39:58 pm
content: That's not (so far) a part of electronics. You're asking in the wrong forum. Try a "free energy" forum instead.

author: Andy Watson
author_rank: Super Contributor
timestamp: October 21, 2014, 09:43:08 pm
content: Quote from: maheanuu on October 21, 2014, 08:59:43 pmWhy?What for?I suspect they do not produce any unexplained phenomena in either hemisphere - i.e. they don't work - so wind the coils whichever way - the results will be the same.

author: c4757p
author_rank: Super Contributor
timestamp: October 21, 2014, 10:11:39 pm
content: Watch your toilet, and wind them in the same direction as it flushes.

author: daqq
author_rank: Super Contributor
timestamp: October 22, 2014, 10:06:05 am
content: Depends on used material - for pure unobtainium it's clockwise with the third harmonic, while adding one counterclockwise twist at every 4th dimension temporal junction (plastic has a lot of these, so wood is preferable). For more mundane materials (102% pure copper, monocrystaline alluminum) it doesn't matter which way you turn, but you must do it whilst chanting - any chant should do, but be careful, and remember,do not summon that, which you cannot unsummon.Translation: I don't think free energy will pop up no matter how you turn them.

author: max_torque
author_rank: Super Contributor
timestamp: October 22, 2014, 12:06:57 pm
content: How can it be "free energy" if you have to buy some wire and spend you time winding coils to harness it?In a similar vein, try asking for just your "free" bar of chocolate under those "Buy one, get one free" schemes you see at the local supermarket.........;-)

author: mikerj
author_rank: Super Contributor
timestamp: October 22, 2014, 03:47:42 pm
content: Quote from: c4757p on October 21, 2014, 10:11:39 pmMight as well throw the cash down there at the same time.
Vout on an HPF with a Simulated Inductor - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: May 21, 2018, 06:19:18 pm
content: Hi,I built the attached HPF circuit. It's Figure 2 from this PDF:http://www.ti.com/lit/an/slyt134/slyt134.pdf.I have my scope set to logarithmically sweep a range of frequencies and am creating a Bode plot. When I connect the scope to the output of the lower op amp (NOT Vout as listed in the schematic), I get the attached scope image which looks perfect to me. However, if I scope Vout as specified in the schematic, I get something (not attached) that looks more like a low pass filter.I was wondering if someone could help me reconcile what I'm seeing on my scope with the schematic.Thanks in advance,Carl

author: eev_carl
author_rank: Regular Contributor
timestamp: May 22, 2018, 02:18:26 pm
content: Here is a picture of my scope where I put the probe at Vout as listed in the diagram. (At the output of the first/top op amp.)These are the values that I'm usingR1 = 10kRS = 50kC1 = 0.047uFR5 = 10kCould the schematic and PDF possibly be wrong in their listing of Vout?Thanks,Carl
Vout p-p tolerance   OR  ripple ? - Page 1
Forum section: electronics / beginners

author: ez24
author_rank: Super Contributor
timestamp: August 08, 2015, 08:18:51 pm
content: From this site:http://webench.ti.com/webench5/power/webench5.cgi?app=powerarchitect&lang_chosen=en_USthere is this setting (default 10%) Lower left corner:Vout p-p tolerance % = ___ %The default number is 10. My questions are:- is this 10% ripple?- is 10% acceptable ripple and can I assume this is for a switching regulator?- if a linear is attached on the output of a switching regulator - what % could be expected ?- would % ripple matter for different voltages ie 10% for 3.3 volts would be bad whereas 10% for 12v would be ok ?? ie should different voltages have different ripple limits?thanks

author: MagicSmoker
author_rank: Super Contributor
timestamp: August 08, 2015, 09:20:45 pm
content: 10% ripple is the default?!?That *might* be acceptable if the output of the switcher feeds a linear regulator, but if it will be used directly then 1% is a more typical spec.Generally speaking, % ripple rather than Vpp is specified because the latter is broadly applicable over a wide range of output voltages. In other words, the same ripple percentage tends to be specified for 3.3V, 5V, 12V, 24V, etc.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 08, 2015, 09:27:20 pm
content: 10% peak-to-peak is, for example 0.5Vpp for a 5V output, and so on. So the voltage varies from 4.75 to 5.25V, if the peaks are symmetrical (which need not be the case).This will most likely be an estimate, at the switching frequency. RF switching noise can greatly exceed this, and depends greatly on topology, component choice and layout. Additional filtering may not be necessary for digital applications, but is typically critical for analog. Additional filtering on the input is also desirable for reducing EMI/RFI emissions problems (depending on situation).Tim
VPP supply max686 - Page 1
Forum section: electronics / beginners

author: tridentsx
author_rank: Regular Contributor
timestamp: February 14, 2013, 07:07:26 pm
content: I am collecting ideas for how to design an universal programmer.My goal is to feed it 5v from USB without the need for additional power feed.The VPP needs to be variable 5v to 25v hence I need some type of boost regulator.How close to the device rated VPP does the VPP actually have to be ? For example if a device needs 12.2v VPP for programming would 12.5v or 12v work? What is normally the current draw from the VPP supply when programming a device?I am thinking that I could use a MAX686 to generate the VPP and to control the voltage of VPP ? my concerns are if the voltage granularity is enough and if the current is enough ?http://www.maximintegrated.com/datasheet/index.mvp/id/1817/t/al

author: c4757p
author_rank: Super Contributor
timestamp: February 14, 2013, 07:30:42 pm
content: Quote from: tridentsx on February 14, 2013, 07:07:26 pmYou're going to have to check the datasheets. For example, the PIC18FXx20 wants 9.0 - 13.25V and draws 300 uA. I found this in the separate reference, "Flash Microcontroller Programming Specification", available on their website. I'd imagine this is similar across the line. Personally I'd aim for no worse than ±5% if you're going to try to make a "universal" programmer.

author: c4757p
author_rank: Super Contributor
timestamp: February 14, 2013, 07:37:26 pm
content: That is an expensive chip. For a bit less you could do this with two PWM outputs on a microcontroller: use one to drive a discrete boost converter at a fixed but unregulated voltage. Run an op amp off this voltage, configured as a noninverting amplifier, then put the other PWM through a low-pass filter into the op amp. Even better, skip the boost converter - just use around 24VDC as the main power supply for the programmer.

author: Alana
author_rank: Frequent Contributor
timestamp: February 14, 2013, 09:08:06 pm
content: From my observations of atmel 89c51 chips that i played with long time ago anything lower than 11.5V on VPP was not enough to program them. I wanted to power my DIY programer and project from the same PC PSU but eventually i ended up with separate PSUs - small 100mA 12VDC unregulated for programmer and PC PSU for project. Those unregulated psus have peak voltage of 14-17V and that was enough for my programer to work correctly.c4757p - you are refering to pickit2 schematic?

author: c4757p
author_rank: Super Contributor
timestamp: February 14, 2013, 09:11:53 pm
content: No, I'm referring tothis.
VTVM vs DVM - Page 1
Forum section: electronics / beginners

author: Lanman100
author_rank: Newbie
timestamp: March 20, 2023, 01:30:02 pm
content: I have a question regarding the use of a VTVM vs DVM. I dabble in repairing old solid state CB radio's (no formal training) and I see some users use a VTVM and others specify a DVM. I realize there are analog meters which technically don't have any vacuum tubes so they can't technically be called a VTVM (more so an analog DVM)? So I guess my question boils down to which one should I use for my purpose and why. Your help is appreciated. Thanks.

author: jonpaul
author_rank: Super Contributor
timestamp: March 20, 2023, 01:31:33 pm
content: VTVM: Vacuum tube from 1960s, like Heathkit V7A.Perhaps 1% accuracy great for tuning.DVM: Digital but some have a bar graph as well for tuning.Jon

author: TimFox
author_rank: Super Contributor
timestamp: March 20, 2023, 02:13:38 pm
content: For RF equipment (receivers, etc.), the instructions may specify a VTVM because it has a 1 megohm (typical) resistor in the probe, next to the point, that isolates the input capacitance of the meter and cable from the node being measured.A typical tube unit had 11 megohm total input resistance on DC, of which 1 megohm was in the probe and the rest was in the voltage-range switch.Some analog solid-state meters had the same construction.Modern DMMs do not have such a probe resistor: you can make your own, adding 1 megohm in the probe, and doing the arithmetic to correct the displayed voltage.If you are measuring the DC voltage at a node with an important high-frequency AC component, the input capacitance of your meter can easily affect the circuit operation and give you an inappropriate DC measurement.Also, when VTVMs roamed the earth, the alternative was a "VOM" analog passive meter, which could have more or less input resistance than 11 megohm, depending on range.A Simpson 260 was rated as "20,000 ohms/volt", so only 50 k on the 2.5 V range, but 20 megohm on the 1000 V range.

author: Lanman100
author_rank: Newbie
timestamp: March 20, 2023, 06:42:33 pm
content: So is it typical today to use a DVM and add series resistance to the probe? Or is there a better way to accomplish that goal?

author: floobydust
author_rank: Super Contributor
timestamp: March 20, 2023, 07:09:42 pm
content: DMM's suck for tuning, they have a chunky coarse shit bar graph, and numbers that are constantly jumping around.A VTVM is superior for tuning, being able to see a peak and adjust for it on the analog meter.They typically come with a high impedance RF probe as well. You'll need one to do peaking i.e.https://www.n5ese.com/rfprobe2.htm
VU Meter(?) Puzzle - Page 1
Forum section: electronics / beginners

author: MoJay
author_rank: Newbie
timestamp: May 28, 2021, 08:36:26 am
content: Hello everyone,I am apprentice as an electronics technician and have my final exam in a few weeks. For this, I have to assemble a PCB (amplifier, the layout is fixed) beforehand. In the exam itself I have to solder an extension to the existing circuit on perfboard (among other assignments, of course).Based on the parts left over in the BOM for the whole project, you can usually guess what the extension will be. 80% of the time it has been some kind of simple op-amp circuit, but not here. I can't quite figure out what one could make with the leftover components. So any help from you people is greatly appreciated.The parts are:1x 2-pole screw terminal3x MOSFET, n channel, IRFZ44N2x Diode, 1N5817 (schottky)1x Diode, 1N40013x LED, red, 2mA1x Capacitor, electrolytic, 220u1x Resistor, 10R(Load resistance on the amplifier is a 3R9, 11W chunker. I do not know if it stays connected in parallel with the extension.)Usually all the components are used, but somecouldbe omitted.My main circuit is a class-D amplifier. The only signal coming from the main PCB is the amp output (signal and ground), since there are no other screw terminals on the main design. The signal will be a 1kHz sine, triangle or square wave with around 9V peak-to-peak.I guess you could grab the 5V supply from a test point, but why wouldn’t they then put a screw terminal for that?I have played around with the components and think it might be some kind of VU meter. However, I can’t think of a working circuit (see the attachment for my sad attempt). Perhaps you know a solution to this puzzle.Thanks again!

author: Chris Mr
author_rank: Regular Contributor
timestamp: May 29, 2021, 08:59:16 am
content: It's interesting that there are 3 LEDs and only a single 10R current limiting resistor. 10R is pretty low for limiting current to an LED.In your circuit the input gets rectified to supply the gates, and the top gate is grounded so would never switch on. If it were a VU meter then the rectified voltage would more likely be the supply for the LEDs. But with only 10R limiting the current, I suspect not.I wonder if it might be some sort of over current detector, to see if the amplifier is short circuited?The MOSFET turn on threshold is 2-4v, and 10R with 2-4v is 200-400mA load current, so probably not.. just a thought.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 29, 2021, 11:49:34 am
content: seehttps://tubecad.com/2017/07/blog0386.htmfor some ideas
connecting Li ion cells in parallel - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: July 20, 2018, 07:09:46 pm
content: hello everyone...I have been so far familiar with connecting 18650 Li ion cells in series its charging and attaching BMS and all. For more power hungry projects connecting these cells in parallel is demanding but I have no idea about what all things is to be considered while doing so.I know one of the important things to consider is that the cells suppose be connected in parallel should be of the same charge to prevent the uncontrolled charging of the weaker cell. So is there any other things to consider while doing this??Also the cells in series could be easily monitered by connecting a BMS but what about the cells in parallel?? is there any circuitry to monitor that both the cells are charging the cells at the same rate so that one cell wont charge the other

author: jeroen79
author_rank: Frequent Contributor
timestamp: July 22, 2018, 07:11:57 am
content: The level of charge would need to be equalized, ie the cells would need to be at the same voltage.Otherwise a large current may flow upon contact.You can do this with a 10 ohm resistor.Once connected in parallel they will effectively be one large cell.For regular charging and discharging you would not need to monitor each cell.If you want to know the health of individual cells you must add a way to disconnect them for testing.

author: Adhith
author_rank: Frequent Contributor
timestamp: July 22, 2018, 07:14:42 am
content: Quote from: jeroen79 on July 22, 2018, 07:11:57 amThank you very much for the reply.
VV/VW Ecig Kick - Page 1
Forum section: electronics / beginners

author: dazq
author_rank: Contributor
timestamp: December 14, 2014, 07:02:51 am
content: Hi guyzwith all the cloned ecig stuff coming from china i thought i would try some of the tech i bought a kick clone but the resistance it will work at is too high it worksbetween 1.6 ohm to 3.6 ohm i would like to change this to 0.5 ohm to 3.6 ohm as i do alot of vaping at low ohm if i tear down the unit and take high res pic can you identify the parts i need to chance to make this possiblethanks daz

author: xwarp
author_rank: Frequent Contributor
timestamp: December 14, 2014, 08:47:33 pm
content: I've been wondering how long it would take before the e-cig stuff would show up.If the "kick clone" is this:http://www.desire-ecig.com/Variable-Wattage-Evolv-Kick-Clone-15WI don't think there anything practical, and more importantly SAFE about what you are wanting to do.Following a local "vapers" facebook page, I see A LOT of idiots playing with fire, and what it sounds like you want to do is redesign a regulated mod to run as if it were a mechanical mod.Playing with such low resistances and those 3.7 lipo's is a very dangerous endeavor and if I were you, I'd look at getting a regulated mod that runs that kind of wattage, or, stick with mechanical.Note: the above is my opinion and the negativity is based on the many posts I've seen where someone figures out how to use a java based ohm's law calculator and then somehow the next day, they are EE's and the only thing they are really doing is putting themselves and others in danger by running such low resistance coils with lithium batteries. YMMV, and there may be people here willing to help.

author: dazq
author_rank: Contributor
timestamp: December 15, 2014, 08:48:08 am
content: hi yes that is the sort of kick i want to mod it must be possible as the official evoled kick dose go down to .5 ohm and good quality battery's like sony vtc 5 is battery that can pull off sub ohms i would not recommend it on a cheap 1-2 amp battery only like a 30amp imr plus as this type is safer than a none imr due to the chemistrybut this is a personal project not something i would want others to try

author: sparx
author_rank: Contributor
timestamp: December 15, 2014, 11:34:12 am
content: From what i've read about LiMn2O4 or "IMR" batteries, is that they are safer if overcharged... nothing is mentioned about safety when they are shorted.I would not want to have an object on my person that has the potential to short a Lithium-Ion battery of any chemistry, simply by the press of a button. Especially one with a 30A discharge rating...

author: amyk
author_rank: Super Contributor
timestamp: December 15, 2014, 03:06:23 pm
content: The problem is that batteries have their own internal resistance, which also dissipates power. As the heater coil resistance decreases, more and more of the power goes into heating the battery instead of the heater, and a hot lion battery is really,reallybad because it's a fire hazard.
W25Q128FW vs XM25QU128B - Page 1
Forum section: electronics / beginners

author: Francisco.s
author_rank: Contributor
timestamp: March 03, 2022, 07:52:00 pm
content: I'm trying to replace the XM25QU128B 1.8V 128M-BIT SERIAL FLASH MEMORY with a similar Winbond W25Q128FW but seems to be some incompatibility.In fact there are many differences, but in the past I have replace XMC's flash memory with chips from other manufactures like Winbond or Gigadevice without any issues.The XM25QU128B chip is the bios from a laptop with boot problems. (only boots from usb but extremely slow)With Winbond W25Q128FW chip programmed with same data doesn't work at all.Need help from an eevblog expert.Thanks.

author: amyk
author_rank: Super Contributor
timestamp: March 04, 2022, 01:28:06 am
content: What's the model of laptop? Have you found a schematic?Comparing the datasheets, one thing that stands out is the Winbond is up to 104MHz while the XMC goes to 133MHz.

author: Francisco.s
author_rank: Contributor
timestamp: March 04, 2022, 06:27:17 am
content: QuoteIt's an acer swift 3 sf314-42 and I have schematic.QuoteI will measure the clock pulses and post its frequency. I think it was 18 Mhz, but can't remember exactly now.Thanks for your answer.

author: Francisco.s
author_rank: Contributor
timestamp: March 04, 2022, 10:08:59 am
content: QuoteThe schematic is a Compal FH4FR LA-J731P. I can send you it if you want.Curiously the schematic shows a W25Q64FW.

author: Francisco.s
author_rank: Contributor
timestamp: March 04, 2022, 07:44:09 pm
content: QuoteI can measure burst of pulses of 120 nanoseconds at pin 6 of XM25QU128B. (APU_SPI_CLK_R)Seems to be not a speed problem, I think.Could be a resistor strap in kbc or apu to select the bios manufacturer?
W2AEW: Question on scope as TDR - Page 1
Forum section: electronics / beginners

author: Stonent
author_rank: Super Contributor
timestamp: July 13, 2014, 07:05:05 pm
content: I watched your latest scope training video today and it was really good. The TDR part, that's really helpful to me. Maybe you can help me figure out something then. It's more network wiring related than RF but I think it uses the same principals of impedance and termination.Now you said at a 1/4 wave it looks like a short. I use a Fluke Etherscope II at work frequently and you can analyze a piece of RJ45 and it will tell you the length, and if the pairs are terminated, shorted, or broken.Where I work, the majority of the network lines are an RJ45 outlet on one end, and an RJ45 plug on the other end that goes directly into the switch ports.Now sometimes the data I get seems to be completely erroneous where it might say 3ft to short and the other lines are ~178 feet to termination. Do you think it's possible that the 1/4 wave problem is appearing? Before this I used to think the Fluke was just some how getting an ohms reading on the cable to determine the problem but now I see it's probably sending a signal down the cable.Is this an issue that occurs at multiples of 1/4 wave like if the cable was 3.25 wavelengths long?And since I'm dealing with CAT5E and CAT6 cable if one of the pairs was not fully twisted or there was too much untwisted when it was crimped, could that crosstalk be misinterpreted as a bounce back from non-termination or a short?

author: miguelvp
author_rank: Super Contributor
timestamp: July 13, 2014, 07:21:47 pm
content: Just adding link to the post of the training video.Yeah I could have just embedded the video but this way it makes people aware of that wonderful thread:https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/msg478471/#msg478471

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 13, 2014, 08:25:14 pm
content: There's no 1/4 wave if there's no frequency -- presumably, the instrument in question tests with pulses spaced out far enough that they don't overlap. An ideal pulse (specifically a spike) contains all frequencies, and what you're actually measuring with a TDR is the magnitude of the dips and peaks at many wavelengths simultaneously.Tim

author: w2aew
author_rank: Super Contributor
timestamp: July 14, 2014, 12:27:15 am
content: As T3sl4co1l stated, this is likely not a case of the transmission line fooling the TDR.An open circuited quarter wavelength line will only appear as a short at the frequency where the line is a quarter wave long. The same holds true for odd multiples of quarter wavelength, as well as odd numbered harmonics of the frequency.
Wago 222 connectors: 20A on the side, 24A & 32A on the bottom - Page 1
Forum section: electronics / beginners

author: Whales
author_rank: Super Contributor
timestamp: July 17, 2020, 08:57:29 am
content: I'm confused by my Wago branded connectors.Websiteand datasheet only mention the 32A rating.Bottom of the connector says both 32A and 24A:Side of the connector says 20A:Perhaps they mean it's only 20A rated when fed 1.6mm to 2mm diam wire? The max rating for these is 2.5mm diam.But then where does the 24A come from? And if any of these numbers are important or standards related, then why are they not in the datasheet for the part?

author: sleemanj
author_rank: Super Contributor
timestamp: July 17, 2020, 09:18:52 am
content: They can take up to 4mm^2 stranded, or 2.5mm^2 solid according to datasheet.32A is for 4mm, 24A is for 2.5mmYou might find more in the the ENEC Licencehttps://electricaldirect-assets.s3.amazonaws.com/product-documentation/dop/831499.pdfI expect the 20A is for whatever "JET" certificate is?

author: Whales
author_rank: Super Contributor
timestamp: July 17, 2020, 09:22:52 am
content: Ah, thankyou.I think it's a bit silly they put these confusing markings on the part but don't provide them in the datasheet.EDIT:Designer 1: Quick, we need to put all of these amperages on the part to show we support all the standards!Designer 2: But how will people understand them?Designer 1: Why does that matter? All they need to know is we haveall the amperages, anything beyond that is fine detail. People need to be able to point to our part and say "Here is a number", especially if they're in the middle of an argument, so we needallof the numbers.Designer 2: Ok then, let's put it in the datashe...Marketing: No! What if the standards or compliances change? All those numbers might confuse people!Designer 2: But we have them on th....Marketing: Don't care! Not our job. The end user hooking these up whilst upside down in a dark attic full of militant possums can work that out, it's their responsibility anyway.The fake Wago 222s I have are more succinctly labelled than these genuine ones. "32A 250V/4kV 0.03-2.5(4.0)mm^2". It seems the cloners understand the user's perspective better than the original company, which probably isn't that far-fetched to understand, given the cloners probably started as users. Albeit of course the clones don't come with the same safety ratings.

author: ledtester
author_rank: Super Contributor
timestamp: July 17, 2020, 10:47:32 am
content: Wago seems to be eager to offer top-notch customer support:
waiting for home type lab and measuring equipment recommendation - Page 1
Forum section: electronics / beginners

author: electronx
author_rank: Regular Contributor
timestamp: June 24, 2020, 11:09:50 pm
content: topic deleted

author: james_s
author_rank: Super Contributor
timestamp: June 24, 2020, 11:33:26 pm
content: There are many existing threads covering all of these topics, I would recommend looking for those first and then ask if you have remaining questions. We tend to see a lot of the same questions asked over and over.
Wake up receiver  - Page 1
Forum section: electronics / beginners

author: Srbinovski
author_rank: Newbie
timestamp: August 17, 2013, 04:50:08 pm
content: Hello all,It will be very much appreciated if you can give me an answer to my question below.I want to build a wake up receiver as presented in the picture attached. I want to build this receiver for 433MHz. As it can be seen in the attachment It is based on an envelope detector, used for an OOK demodulation. A voltage multiplier (VM) is used as an OOK signal envelope detector. This demodulated signal is fed to the data slicer, which raises the demodulated digital signal to voltage levels that can be used in later digital circuitry. The comparator threshold is adaptive, rather than constant and is determined by the wake-up signal strength.I want to optimize this circuit so I found an equation for the optimum number of stages of a VM: Nopt=3/4 *( Vout/Epk) +1/8. To be able to calculate this I have to know the peak voltage of my signal.Let's assume that a wake up signal arrives at -50dBm which is very close to the min sensitivity of the selected diode HSMS-285C (-57dBm@916MHz). I assume that it will be similar for 433MHz. If we assume that we have ideal matching for the 50ohm antenna, will this mean that the voltage that my VM will see will be equal to Epk=1mV (-50dBm -> Epk=1mV) or there will be a drop because of the load? The load obviously is the voltage multiplier circuit plus my comparator (which has fairly low bias current 2nA) and the R&C combination on the - input of the comparator used for "adaptive thresholding".Maybe I am wrong but, I think if there is ideal matching circuit the energy transferred from the antenna to the VM will be equal and the VM will see a Epk = 1mV.Many thanks in advance for your replies and all the best,Srbinovski Bruno.
Waking up esp32 using a mpu6050? - Page 1
Forum section: electronics / beginners

author: Rishles69@
author_rank: Regular Contributor
timestamp: May 24, 2024, 07:57:02 pm
content: I was wondering if I could use a mpu6050 to wake up esp32 on a specific direction like in smartwatches. I first tried to use the int pin of the mpu6050 to wake up esp32 from deep sleep. But the problem is, it wakes up the esp32 even in a slightest motion. Then I thought this: let the int pin of the mpu 6050 send an impulse. And it wakes up the esp32. As I'm using a display, I thought, let it use a transistor to switch on and off the display. So if it send an impulse, let the esp32 wake up (still the display is off). Now the esp32 is turned on, it should check which direction I have hold the gyro or mpu6050. And if it sees I have hold it in right direction, the display turns on. And if I hold it in other directions it doesn't turn on and back to sleep. So here, this should be done at 1 second maximum and I don't think if esp could handle it. Any ideas?

author: xvr
author_rank: Frequent Contributor
timestamp: May 25, 2024, 08:35:07 pm
content: Quote1 second is a lot of time. ESP can do a lot in 1 second. Just use appropriate sleep mode that can be awaken fast.

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 26, 2024, 08:46:51 pm
content: You have to use the Interrupt pin of the MPU6050. It will generate interrupt and wake up the ESP32 from deep sleep.
Walkie Talkie activating button - Page 1
Forum section: electronics / beginners

author: dleebell
author_rank: Contributor
timestamp: March 17, 2015, 09:48:17 am
content: HiI've got a project where I am wanting to use two walkie talkies (WT) with an add on feature. Basically i want to have both walkie talkies with a button. Where one of the walkie talkies is able to activate the other button. So...Walkie Talkie 1: Button Off = Walkie Talkie 2 Button OffWalkie Talkie 1; Button On = Walkie Talkie 2 Button OnThe system only works one way where WT1 activates WT2.I have been told that I can send informaton via walkie talkies using either a 556 Chip or a Nordic nRF24L01 Chip, both of which send an audio frequency. Either on will be connected to WT1 and my arduino connected to WT2.Are there any other ways of activating the button through the WT's (wirelessly) without playing an audio that can be heard?Or is it a matter of just raising the frequency to the extent of not being picked up by the human ear...Many ThanksDominic

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: March 17, 2015, 12:56:36 pm
content: Not quite sure exactly what this is for but if you disconnect the speaker from the receiving unit the audio being transmitted won't be heard.

author: dleebell
author_rank: Contributor
timestamp: March 17, 2015, 01:04:58 pm
content: It's for a project of mine at uni.So if I disconnect the speaker for the period of 'deactivating' or 'activating' button the arduino is still able to pick up the frequency? From which chip 556 or Nordic nRF24L01.many ThanksDom

author: Howardlong
author_rank: Super Contributor
timestamp: March 17, 2015, 01:08:16 pm
content: Assuming you want this in-band, have you considered sub-audible tones? Look up CTCSS or PL tone.

author: G7PSK
author_rank: Super Contributor
timestamp: March 17, 2015, 01:45:35 pm
content: Many two way's come with a repeater function these days, usual y works with a CTCS or.DTMF

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: March 18, 2015, 10:11:14 am
content: Quote from: dleebell on March 17, 2015, 01:04:58 pmYou could disconnect the speaker permanently if you wanted. It doesn't alter the radio's behaviour. Just like how a portable radio doesn't stop playing when you unplug the headphones.
wall outlets measuring weird frequencies above 60Hz? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: July 11, 2016, 01:15:17 am
content: Why would a wall outlet that measures just fine at around 120V AC not read 60Hz on my multimeter?There was a brownout and a power surge in our neighbourhood this morning and a nearby office lost power to one end of the building upstairs.I went to check it out and two "powerbars" were dead (one blew black soot out of a socket) but luckily the two computers and the DSL box connected to them were fine.I went back home to test my multimeter just in case the frequency measurement was not working but it's reads a solid 60Hz here.What would make all the outlets in a building measure random frequencies around 80/90/100Hz on my meter?It would be interesting to see what the waveform looks like but I don't have anything portable I could bring there to test it.

author: amyk
author_rank: Super Contributor
timestamp: July 11, 2016, 01:47:26 am
content: There's probably lots of noise from other equipment. Equipment with SMPS shouldn't be affected since they rectify the input anyway.

author: rstofer
author_rank: Super Contributor
timestamp: July 11, 2016, 02:31:37 am
content: Any other problems in the area. Maybe an ongoing arcing situation could cause something like that. Loose wire arcing?

author: IanB
author_rank: Super Contributor
timestamp: July 11, 2016, 02:46:15 am
content: Also, make sure you are using a "Low-Z" mode on the meter.You could emulate this by connecting a resistive load like an incandescent lamp to the outlet before measuring the frequency.

author: dentaku
author_rank: Frequent Contributor
timestamp: July 11, 2016, 01:23:46 pm
content: Quote from: IanB on July 11, 2016, 02:46:15 amInteresting.

author: Curtis
author_rank: Contributor
timestamp: July 11, 2016, 03:14:12 pm
content: A lot of high rise buildings some times have similar problems because there are a lot of computers that have"non linear"power supplies which introduce"harmonics"to the electrical grid. Switching power supplies and such can, and often inject harmonic waves, and voltages that can cause all kinds of weird things to happen in the electrical system.We also see this phenomenon where a electrical system can act like a"antenna"to pick up"rf"energy, and then these frequencies can be heard throgh audio amplifiers connected to the same grid system.
Wall wart output voltages seem high - Page 1
Forum section: electronics / beginners

author: JuiceKing
author_rank: Regular Contributor
timestamp: May 07, 2012, 02:26:28 pm
content: Hi,Like many of us, I have an extensive collection of wall warts, but before plugging them into non-matched equipment, I thought I'd check voltages.The few that I'd like to use more seem quite high and it makes me concerned about using them in other equipment.For example, a 6V-rated one (no brand) outputs 9.96V, and the 9V one (Sony-brand) outputs 11.87V. Both are pretty big and heavy, so I think they have linear PSUs inside.Is it normal to have such output voltage? Are they expected to drop under load?- Ken

author: T4P
author_rank: Super Contributor
timestamp: May 07, 2012, 03:46:23 pm
content: That would mean they are unregulated. They only put out rated voltage at max current.Whether you can use it or not depends on your equipment, if it can handle 12v at connection. Like example for a 9V packSmall transformers usually have terrible regulation and even those old ones from panasonic i found are so poor they put out 17V when their rated voltage is 9V

author: Flávio V
author_rank: Regular Contributor
timestamp: May 07, 2012, 04:41:18 pm
content: It is one of the reasons than i am planing to replace all of my house's supplies with some custom made switched ones...and i am not going to talk about efficiency...than are normally near 30-60%..

author: JuiceKing
author_rank: Regular Contributor
timestamp: May 07, 2012, 06:21:35 pm
content: Makes perfect sense. Thanks!- Ken

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: May 07, 2012, 07:28:57 pm
content: For perhaps more than you want to know, check out my article:AC-DC Power Supplies - Using Wall Warts

author: Mint.
author_rank: Frequent Contributor
timestamp: May 08, 2012, 02:08:05 am
content: Shouldn't you put a load on the supply first?

author: JuiceKing
author_rank: Regular Contributor
timestamp: May 09, 2012, 11:00:33 pm
content: Jon, fantastic tutorial...answered all my questions and then some. Thank you!

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: May 10, 2012, 01:08:15 am
content: Thanks for the kind remarks Ken.
Want a cheap way to measure light-source's spectrum - Page 1
Forum section: electronics / beginners

author: cejoba
author_rank: Regular Contributor
timestamp: November 18, 2022, 01:06:07 pm
content: Hi.I want to measure several lamp's light spectrum, similar to this:https://www.researchgate.net/profile/Muhammad-Jahandar/publication/330372622/figure/fig1/AS:722887845625858@1549361301844/Fig-2-Spectra-of-the-different-indoor-light-sources-a-Xenon-lamp-b-incandescent.pngAre there any instrument can do such thing, while affordable for a hobbist?Thanks.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 18, 2022, 01:42:16 pm
content: How about this one?https://github.com/leswright1977/PySpectrometer2

author: RoGeorge
author_rank: Super Contributor
timestamp: November 18, 2022, 02:03:27 pm
content: The cheapest way would be to get a CD (Compact Disc, can be any other diffraction grating) and shine the light on it's mirror face, then look with the naked eye at the reflected rainbow, and thus probe each light source one by one.

author: jonpaul
author_rank: Super Contributor
timestamp: November 18, 2022, 02:57:17 pm
content: glass prisim

author: Terry Bites
author_rank: Super Contributor
timestamp: November 22, 2022, 11:22:20 am
content: Osram have some nice new products eg AS7343 they have an eval kit. A ready made solution I think. No idea of the cost.Maybe put a ping pong ball diffuser on the front of a cheap usb camera and maybe dump the lens. See this as well:www.geeksforgeeks.org/detect-the-rgb-color-from-a-webcam-using-python-opencv/

author: voltsandjolts
author_rank: Unknown
timestamp: November 22, 2022, 12:29:04 pm
content: Photodiode array spectrometer.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 22, 2022, 05:05:05 pm
content: Over the years, a bunch of these have been featured on Hackaday:https://hackaday.com/blog/?s=spectrometerUsing a color camera is not of much use, as it only detects RGB values. But either a diffraction grating or a prism combined with a linear CCD or CMOS sensor can work. A 2d sensor in the form of a (monochrome) camera probably works just as well and is easier to obtain these days. A 2D camera has advantages, you can use some averaging, or tilt it a bit (or both) to increase resolution.I think MikesElectricStuff once tore an old unit apart which had a single photo sensor, a prism and a stepper motor with some method to rotate the prism.
want to add cooling fan - Page 1
Forum section: electronics / beginners

author: raven_1970
author_rank: Newbie
timestamp: September 19, 2015, 11:31:24 am
content: hi there to all newbie hereso first posti got an awia hifi from a friend but i think it has a problem with heat it work fine for a while then it will shut off..i disconect from power let it stand for a while reconect to power works ok then off again.its a late 1980 early 1990s modle so i was wondering if it is possable to conect a 12v cooling fan? i know i could use a 12v adaptor but i want to solder it to the board some how so the fan will turn off and on when the power swich is used

author: Rerouter
author_rank: Super Contributor
timestamp: September 19, 2015, 11:45:42 am
content: First we are going to need some more info, e.g. if its a sealed box then a cooling fan will not help, if it has vents, its probably full of dust and needs to be blown out, and in both cases, its likely a dry solder joint or failing capacitor that is causing your issue,
want to add led indicator for "current limit" - Page 1
Forum section: electronics / beginners

author: bengaltiger
author_rank: Newbie
timestamp: August 08, 2012, 10:04:30 am
content: Hi,I want to add LED indicator for "current limit" in the following circuit.http://www.zen22142.zen.co.uk/Circuits/Power/l200.htmlPlease help.Regards,BT

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 08, 2012, 05:47:31 pm
content: There are a couple of ways to do this.Measure the voltage difference between pins 5 and 2. A difference of 0.45V will indicate that the regulator is limiting the current.Measure the voltage at pin 4, relative to ground. A voltage less than 2.77V will indicate that the regulator islikelylimiting the current.The attached schematic is an example of a circuit that implements case #2 above. It uses a TL431 as a comparator. When the voltage at pin 4 drops below ~2.77V the LED will come on.You would likely want to place a small cap across R2 and would probably need to tweak R1's value for a real-life circuit. Also, it might be necessary to either use an LED with a fairly high Vf or add a diode or two in series with the LED to ensure it stays off when it should.Another option would be to use a comparator with a built-in voltage reference to implement a similar circuit.

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 08, 2012, 10:25:31 pm
content: I was bored so I drew up a schematic that implements case #1 mentioned in my earlier post. As you can see it requires a few more components. R1 would be Rsc, the current sense resistor between pins 2 and 5 of the L200.U2 can be replaced by a comparator with a built-in voltage reference. This would eliminate the subcircuit that generates Vref as well.

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 11, 2012, 07:53:18 pm
content: I guess it probably doesn't matter since the OP seems to have created this topic and then immediately fell off the face of the earth but if anyone else is interested I built these circuits on a breadboard and they work fine.

author: grumpydoc
author_rank: Super Contributor
timestamp: August 11, 2012, 11:01:48 pm
content: Well, Bengall Tigersarean endangered species....
want to generate a 50 hz 240 v sine wave from dc 12 volts. - Page 1
Forum section: electronics / beginners

author: saipavan
author_rank: Contributor
timestamp: March 05, 2014, 07:28:11 am
content: i would like to generate a 240 volts sine wave from 12 volts dc .i am trying to get the mains voltage from a battery as an emergency power.(i would like to get a general schematic)thanks in advance......

author: lapm
author_rank: Frequent Contributor
timestamp: March 05, 2014, 07:43:58 am
content: Well not an easy task your are asking, since not all ac powered devices like it if voltage is not exactly sine wave... I would recomend buy cheap ready made unit. Much safer too if you dont have experience dealing with ac circuits.In my country i can get small inverter as cheap as 30 - 50 euros, witch in my standards is cheap... Not much point building one unless your doing it to learn or just dont have any other choise...Emergency power really docent need much, charge your phone, some led lights going... Anything power hungry you are usually better of getting yourself real generator anyways...

author: saipavan
author_rank: Contributor
timestamp: March 05, 2014, 07:47:47 am
content: i want to power my small electronic hobby projects.i want to learn by designing an inverter(dc to ac converter).

author: ml-eng
author_rank: Contributor
timestamp: March 05, 2014, 08:05:22 am
content: no good project for beginners/hobbyist

author: saipavan
author_rank: Contributor
timestamp: March 05, 2014, 08:36:09 am
content: this isa not only my hobby but also my stream of study.so i would like to know about it ,how ever complex it may be.....

author: Codemonkey
author_rank: Regular Contributor
timestamp: March 05, 2014, 09:29:06 am
content: So instead of you wanting someone else to do all the work for you and give you a ready made schematic, why not try designing one ?A few seconds search on google is enough to find multiple designs, but so far it seems you've put in the absolute minimum amount of effort possible by just asking others to do all the work for you without even providing the most basic of requirements (how much power will you expect to run from it etc). Not the right attitude for any future engineer.

author: BravoV
author_rank: Super Contributor
timestamp: March 05, 2014, 09:56:12 am
content: Find your answer ->HEREand don't be lazy.

author: saipavan
author_rank: Contributor
timestamp: March 05, 2014, 11:34:57 am
content: i am sorry i didnt give enough information .actually i am not an undergrad now.i didnt check in the internet well.i will do that from the next time.
Want to kill RF oscillation from audio amplifier IC - Page 1
Forum section: electronics / beginners

author: Northe
author_rank: Newbie
timestamp: March 09, 2024, 11:00:41 pm
content: I bought a Joyo JA02-II 5 W battery guitar amplifier. My intent is to use it with crystal radios and to make probes to use it as a signal tracer. It works fine, and using it's "overdrive" function gives me a lot of gain. I actually sounds pretty good, too.However I discovered that the amplifier has a free-running oscillation from the CS81385 IC amplifiers in the mf broadcast band. If I put my finger on the IC it moves the frequency, may even stop it, but take my finder away and it drifts back to approximately the same frequency. I tried wrapping aluminum foil around the amplifiercase, which substantially reduced the radiation.I'm wondering if someone can offer suggestions to stopping the oscillation without a a lot of work on the teensy-weensy PC board with macroscopic surface-mount components. I figure worst case I could shield the inside of the plastic case with copper foil tape or carbon paint, but would really like to be able to actually kill the oscillation.Thanks in advance for any suggestions.

author: BrokenYugo
author_rank: Super Contributor
timestamp: March 09, 2024, 11:19:32 pm
content: CS3138S (not 5) looks to be a class D amplifier, it's supposed to run at a high frequency, just not let that out. You probably need more filtering on the output and maybe power input, but that's hard to say with no pictures of the board or schematic. Looks like the datasheet is Chinese only. Switching frequency is stated at 500kHz which would put the second and third harmonics right in the AM broadcast band, so that's probably what's going on.https://datasheetspdf.com/mobile/978910/CHIPSTAR/CS8138S/1Note the couple mentions of ferrite beads and 1nF caps to ground on the two output pins, are those present?

author: Northe
author_rank: Newbie
timestamp: March 10, 2024, 08:49:55 pm
content: Thank you.You have reminded me of my ignorance concerning class D audio amplifiers.After peering at the mostly Chinese data sheet using Google Translate it finally occurred to me that it was a class D amplifier. And, yes, the interference is more or less around 1500 kHz. So far I have not seen a schematic, for the amplifier board but I'd place a bet that the design is probably standardized and used in a number of entertainment applications. I'll keep searching for one. And yes, it really seems that the RF is getting out primarily through the speaker/output pinsAs far as the filtering on the output/speaker pins, there are lots of surface-mount chips on, but I'll have to peer even closer to see if there is any evidence of ferrite beads. So far it appears that adding a 0.22 or 0.33 uF capacitor right across the output pins may be killing the signal emission with the amplifier still functioning. It's difficult to tell because I'm using 400 V caps and touching the pins with the leads. I'll probably see what sort of small low voltage caps I can order so I can tack them on the board.Thanks again!Northe