hybridfree/eevblog-posts huggingface dataset:
FX-971 or FX-951 ? - Page 1
Forum section: electronics / beginners

author: PLPascal_Srabrakmar
author_rank: Newbie
timestamp: August 06, 2023, 09:44:56 am
content: Hello,I hesitate between the FX-951 which is at the end of production and the FX-971This would be for general purpose use, macbooks, smartphones, laptops, tvs, tv power supplies, 220V cables etc.The FX-971 has some advantages, the new tip system, no need for wires for sleep mode, but unfortunately you have to wait 1 minute for sleep mode otherwise you have to press the buttonThe FX-951 does not have the same system for changing the tips, and makes 70W against 90W for the FX-971, do you think that makes a big difference?What choice would you have made?Thanks

author: Shock
author_rank: Super Contributor
timestamp: August 06, 2023, 06:37:26 pm
content: The main things I noticed is it's still a little slow heating, you need to press way too many keys for a simple temp change, no tweezer handpiece support like their multichannel stations, swapping a handpiece requires the unit to be powered off. Overall quite a lot of plastic.Upsides is they moved on from the tip sleeves, small display and lockout key of the FX951. I'm not entirely convinced copying JBCs ideas for tip swapping was a better move, tip storage for a few tips in the stand is handy however. After you have half a dozen tips though better to use a larger separate rack which will make any stand tip swapping system become obsolete due to double handling.Pace is my preferred brand. Metcal if I wanted to spend a bunch more money.

author: Veteran68
author_rank: Frequent Contributor
timestamp: August 06, 2023, 07:47:14 pm
content: Quote from: Shock on August 06, 2023, 06:37:26 pmI second that. Love my Pace.

author: liaifat85
author_rank: Regular Contributor
timestamp: August 07, 2023, 07:36:09 am
content: Considering the tip-changing system, I vote for FX-971.
FX8801 iron for FX888 station and 907 iron for 936-12 station compatibility - Page 1
Forum section: electronics / beginners

author: vehf277
author_rank: Contributor
timestamp: November 19, 2012, 11:58:10 pm
content: Hi everybody!Can anybody tell something about Hakko FX8801 iron for FX888 station and 907 iron for 936-12 station compatibility part-by-part?Thank you in advance!
FY6600 or  FY6800 - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: December 08, 2018, 11:03:52 pm
content: what differences there are, between the faytech 6600 and the 6800, it is worth the 6800. it is for occasional use in the electronic hobby.no more than u $ s 100, until there my budget, to be companion of mo Rigo ds1054z.
FY6800 because so cheap ?? - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: July 20, 2018, 06:01:15 pm
content: FY6800 because so cheap ?? I compare prices with other sellers, and it is approximately 60% cheap, it smells like a trap !!!https://www.ebay.com/itm/FY6800-DDS-Signal-Generator-0-01-100MHz-Function-Arbitrary-Waveform-Pulse/123260335508?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160727114228%26meid%3Da72f3de8584845b3bca93998b7510964%26pid%3D100290%26rk%3D2%26rkt%3D4%26sd%3D183335343676%26itm%3D123260335508&_trksid=p2060778.c100290.m3507

author: tsman
author_rank: Frequent Contributor
timestamp: July 20, 2018, 06:44:54 pm
content: Looks like a scam. Look at their feedback and you'll see they've only sold a small quantity of toys and small car parts.

author: ignator
author_rank: Regular Contributor
timestamp: July 20, 2018, 09:21:13 pm
content: The price for the all models is the same (USD $45) and is way too low.I don't know what the game is, unless you fail to report not receiving it, and they run away with the paypal money. But they also get your ebay user name, address, and email address.The one negative feedback was wrong item sent. There's some game with that.I just purchased the new model from Aliexpress, very happy, it was USD $105, free shipping.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: July 20, 2018, 09:27:06 pm
content: Yes, I thought the same, first I thought it was an auction, but then I saw that it was the price, and only 32 product sales all mixed.

author: Cliff Matthews
author_rank: Unknown
timestamp: July 20, 2018, 09:58:42 pm
content: Yup, flagged that a few days ago in another thread on a UT181a. With 132 items in the store and just 32 reviews
fy6900 modify led color - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: March 02, 2020, 01:41:46 am
content: Some time ago I saw a video where a youtuber modified the color of the LED colors of the buttons of the fy6800, modifying a resistor, I wanted to do it with my fy6900, but I do not find the video, someone knows how it is done.in spanishhace un tiempo vi un video en donde un youtuber modificaba el color de los colores del led de los botones del fy6800, modificando una resistor, lo quise hacer con mi fy6900, pero no encuento el video, alguien sabe como se hace.
gain bandwidth product at a particular fo? - Page 1
Forum section: electronics / beginners

author: SArepairman
author_rank: Frequent Contributor
timestamp: February 23, 2014, 04:32:02 am
content: What is Fo when dealing with gain bandwidth product?http://cds.linear.com/docs/en/datasheet/100737fbs.pdfif you look under gain bandwidth product it specifies the condition fo = xkhz.What does this mean?I want to know how much gain I can put on a certain signal... normally I would divide GBW by the gain... but how do I add the condition to the "formula"?what does it matter? why is it specified? what are the nonidealities? how should it effect my decision to use a certain part?

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: February 23, 2014, 04:44:27 am
content: Perhapshttp://www.ti.com/lit/an/slyt383/slyt383.pdfwill answer your question

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 23, 2014, 04:51:48 am
content: Referring to Voltage Gain vs. Frequency (pg. 6), note the prominent slope where gain is dropping with frequency over six or seven decades (it makes a very good integrator!). This slope is guaranteed by design (as is the parameter itself..), so all that matters is measuring the gain at a particular frequency in that range. From that, you know all points on that line, including where it intersects unity (G = 1).Damn, that's a nice amp too, I'd pay ten bucks if I needed one. And they aren't even that, more like five bucks.Tim
Gain bandwidth product is not what the datasheet says. - Page 1
Forum section: electronics / beginners

author: Mercator
author_rank: Contributor
timestamp: September 20, 2016, 03:39:15 pm
content: Hi,Originally, I wanted to design a single high-gain amplifier (Av = 100) for a 40kHz sinusoidal signal. So I started simulating the design in LTSpice using LT's built-in components to save some time. However, the gain at 40kHz was about 70% lower than I expected. So I stripped down the circuit until I was left with a voltage follower with unity gain (see attached image).The datasheet says that the gain bandwidth product (GBWP) for the LTC6240 is 18Mhz. However, the bode plot of LTSpice says that it is only about 130kHz. How can that be? Or did I misunderstand the concept of GBWP?Thanks in advance.

author: Kalvin
author_rank: Super Contributor
timestamp: September 20, 2016, 03:48:28 pm
content: What happens if you give the op amp some negative power supply voltage, like -1V, instead of 0V.Edit: You may also want to increase the AC voltage to 100mV to get started, then reduce it gradually to 50uV and observe what happens.

author: Mercator
author_rank: Contributor
timestamp: September 20, 2016, 05:23:26 pm
content: Quote from: Kalvin on September 20, 2016, 03:48:28 pmGiving it positive 2.5V and -2.5V (according to the datasheet it needs 5V from V- to V+) leads to a bandwidth of 8Mhz. Much better than before. Thanks. However not 18Mhz as claimed.Quote from: Kalvin on September 20, 2016, 03:48:28 pmSame result as before. Sorry.

author: Chalcogenide
author_rank: Regular Contributor
timestamp: September 20, 2016, 05:34:15 pm
content: The GBWP does not necessarily corresponds to the bandwith of the opamp when used as a buffer, it's just the product of the DC gain times the frequency of the dominant pole. If you look on the datasheet of the LTC6240 you can see that there is an additional pole at around 1MHz, followed by a zero right around 5 MHz. The gain crosses 0dB at around 5 MHz or so, and the bump you see in the frequency response around 2.5 MHz is probably a slight peaking due to the phase margin being less than 90°.

author: StillTrying
author_rank: Super Contributor
timestamp: September 20, 2016, 05:59:10 pm
content: I've not looked at the data sheet, just drawn it.GBW seems about 12MHz, at x1, and 25MHz at x100. ~18M on average.

author: Mercator
author_rank: Contributor
timestamp: September 20, 2016, 06:12:44 pm
content: Quote from: StillTrying on September 20, 2016, 05:59:10 pmYou're right! Just went back to Av = 100 and I got a bandwidth of about 175kHz, i.e. GBWP is about 17.5 Mhz. So close enough.Thanks to all of you!

author: StillTrying
author_rank: Super Contributor
timestamp: September 20, 2016, 06:24:58 pm
content: Quote from: Mercator on September 20, 2016, 06:12:44 pmI seem to remember it was about 250kHz at x100, which is just about enough to output at 2Vp-p 50kHz square wave.47R and 4K7 gave about the best BW at x100.
Gain chip - Page 1
Forum section: electronics / beginners

author: alamwte
author_rank: Regular Contributor
timestamp: January 21, 2021, 06:45:22 am
content: Hello,I am looking for a tunable laser diode to tune its wavelength in range of 1550nm that I found Gain-chip.Would you tell me what is Gain-chip and what is its difference with tunable laser diode?Thanks

author: mikerj
author_rank: Super Contributor
timestamp: January 21, 2021, 01:41:36 pm
content: A gain chip is simply a semiconductor optical gain device which is required at the heart of any solid state laser. However a gain chip by itself is not useful as a laser, they are designed to be used in conjunction with an external cavity so you would have to add the grating, mirrors, isolator etc. and get everything aligned, not a job you could do without some fairly specialised equipment.

author: Zero999
author_rank: Super Contributor
timestamp: January 21, 2021, 01:56:16 pm
content: Over what range does the laser need to be tuned? I admit I don't know much about lasers. I would think you need to adjust the resonant frequency of the optical cavity, to tune the laser.Again, as I asked in the other thread, what's the purpose of the project? What are you trying to achieve?

author: alamwte
author_rank: Regular Contributor
timestamp: January 22, 2021, 06:19:18 pm
content: Quote from: Zero999 on January 21, 2021, 01:56:16 pmI need a tunable laser diode for my SFP modules. I have a SFP module that uses a laser diode with 1550nm wavelengthsNow I want to have another wavelengths near 1550nm for DWDM device . I want to have a tunable laser diode that I can use for every other SFP module and I just adjust it and have different wavelengths in my SFP modulesWhen I searched for this tunable laser I found Gain chip and I didn't know can I use it instead of laser diode.
Gain Compression Measurements Using a VNA - Page 1
Forum section: electronics / beginners

author: fourierpwn
author_rank: Regular Contributor
timestamp: September 23, 2021, 11:40:53 am
content: Hi all,As the theory states, when an active device or an amplifier is driven into saturation, the output is no longer sinusoidal with some of the power being present in the harmonics. Doing S-parameter measurements under such conditions would result in an inaccuracy of data. A feature within many VNAs is 'gain compression'. Disregarding equipment such as a PNA-X/NVNA, how do VNAs measure saturated power/gain compression accurately?
Gain control - Page 1
Forum section: electronics / beginners

author: elki
author_rank: Regular Contributor
timestamp: August 24, 2024, 11:43:45 am
content: Is there any way to mitigate the effect of a parasitic capacitance in a digital pot when introducing it to the feedback of an op amp? This is for a very high bandwidth application (> 100 MHz). Just wondering if there is a way to replace a manual pot with a digitally-controlled one. From what I have seen, for a high bandwidth, there is no way to get away with a digital pot in the feedback without severely limiting the bandwidth of a circuit. Are there any alternatives of how to control the gain of an op amp? PGAs are usually limited in bandwidth.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 24, 2024, 12:19:07 pm
content: You may want to use an analog multiplier IC (often based on a Gilbert Cell) instead of a gain potentiometer.An analog multiplier will give you voltage control of amplification, without all the drawbacks a potentiometer might have (being it either an analog or a digital pot). If you need MCU control over gain, then a variable DC voltage is easy to synthesize using either PDM, PWM, or a DAC.Random example of an analog multiplier IC with a bandwidth of 250MHz:https://www.analog.com/en/products/ad835.html

author: David Hess
author_rank: Super Contributor
timestamp: August 25, 2024, 07:15:37 am
content: Quote from: elki on August 24, 2024, 11:43:45 amA compensating capacitance can be added, however the required capacitance changes with digital pot setting, so this is not very practical.
Gain in Decibels for a Transimpedance Amplifier - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: May 05, 2021, 08:28:57 pm
content: The gain of a transimpedance amplifier is written as the following:VOUT= -IIN*RFTypically, you can convert the gain to dB by taking the log of VOUTover VIN, but since the TIA calculates its gain a different way, how do you do that?https://en.wikipedia.org/wiki/Transimpedance_amplifier

author: magic
author_rank: Super Contributor
timestamp: May 05, 2021, 08:32:16 pm
content: LTspcie will happily report gain of 40dB if you pass "AC 1" current through 100Ω resistance. So it simply divides Vout/Iin and ignores the units.If I ever see TIA gain reported in decibels, that would be my first suspicion.editIf you want to be pedantic, you can do the above but write dBΩ instead of dB - that's supposed to be decibels with respect to 1V/A of transimpedance.LOL, I just searched "dBΩ" and it even seems to be a thing...

author: LoveLaika
author_rank: Frequent Contributor
timestamp: May 05, 2021, 08:53:01 pm
content: Thanks. That helps a lot. Its rather strange how TIA gain relies only on Rf. I mean, i get the logic behind it, but still.In that case, when you take the log of Rf (which is Vout/Iin), ignore the units, you get dBΩ, but is that really the gain? A part of me feels like there's something I'm not understanding.Also....given the nature of the TIA, I can see why the gain would be thought of as simply Rf, but why are you suspicious about TIA gain in decibels? Yeah, that's a weird way to write it, but why?

author: Nitrousoxide
author_rank: Regular Contributor
timestamp: May 06, 2021, 03:29:11 pm
content: Quote from: LoveLaika on May 05, 2021, 08:53:01 pmThat's essentially it. Decibels are simply a logarithmic base 10 way of representing a value. It doesn't always have to be power or voltage. It can be pressure, temperature... in fact any unit you wish.

author: TimFox
author_rank: Super Contributor
timestamp: May 06, 2021, 03:53:32 pm
content: Specifically, the “value” that goes into the logarithm is always a ratio. The optional suffix (e.g., “m” in dBm) is the denominator in the ratio. When the two terms (e.g., PINand POUT) have the same units, the suffix is not necessary.

author: David Hess
author_rank: Super Contributor
timestamp: May 07, 2021, 08:54:34 pm
content: I am not sure if this is what you are looking for but current feedback amplifiers have *two* inputs, with one being a voltage and one being a current. The current input, which goes to the emitter or emitters, has transimpedance gain which is measured in ohms for current in and voltage out. But that current input is referenced to a voltage input, at the base or bases, which has voltage gain and could be measured in dB.

author: LoveLaika
author_rank: Frequent Contributor
timestamp: May 11, 2021, 03:17:33 pm
content: Thanks. That's an interesting thing to consider.
Gain of common emitter amplifier with the presence of bypass capacitor - Page 1
Forum section: electronics / beginners

author: promach
author_rank: Frequent Contributor
timestamp: July 02, 2020, 02:20:56 am
content: How to derive the corrected gain with the presence of bypass capacitor on page 35 ofhttps://web.archive.org/web/20160331140729/http://ardem.com/d_oa_rules&tools/Ch 08.NDI & EET.pdf?

author: garethw
author_rank: Regular Contributor
timestamp: July 02, 2020, 06:48:52 am
content: The capacitor has an impedance instead of a resistance.Ignoring phase, the "resistance" part of the capacitor changes with frequency. In lay terms, at high enough frequencies the capacitor is a short circuit.During AC analysis, the capacitors are assumed to be shorted. This means that R is completely bypassed by the capacitor (a short) to ground. Hence the R turns to zero in the equation.Remember that if you build this circuit and apply a DC signal, you will get the original gain of 6dB. The gain will increase as you increase the frequency up to a maximum of 36dB. This could be plotted to give you a simple frequency response of your amplifier.

author: promach
author_rank: Frequent Contributor
timestamp: July 03, 2020, 12:16:16 am
content: Where does 159 in the equation for f1 come from ?

author: fourfathom
author_rank: Super Contributor
timestamp: July 03, 2020, 12:48:50 am
content: 1/2Pi = 0.159 (approximately) I haven't bothered to look for the x1000 factor.
Gain - Page 1
Forum section: electronics / beginners

author: Cujo
author_rank: Regular Contributor
timestamp: September 05, 2021, 05:58:37 am
content: How to find the gain as the ratio of the amplitudes of the output and the input voltage from a sinusoid?

author: bob91343
author_rank: Super Contributor
timestamp: September 05, 2021, 06:06:14 am
content: Divide the output amplitude by the input amplitude. It can be rms or peak to peak or just peak.

author: CaptDon
author_rank: Super Contributor
timestamp: September 06, 2021, 09:55:24 pm
content: And how do you want that gain expressed?In decibels or as a simple fractal ratio??There are so many on-line Decibel calculators I am surprised you posted the question here.I often just 'approximate' the gain remembering power ratios of double =3db quadruple=6Db and tenfold =10Db. But remember voltage ratios are a bit trickier, A 10 to 1 increasein voltage is 20Db in power all else being equal, 10 times the voltage causes 10 timeshigher current flow and the power increases 100 times or 20Db (10X10=100 or a 20Dbpower ratio). In radar we use DbK (decibels over 1 kilowatt) for transmit powers, but stilluse receiver merit ratings of Db below 1 milliwatt with typical echo signals running lowerthan -120Dbm or 120 decibels below 1 milliwatt.

author: TimFox
author_rank: Super Contributor
timestamp: September 06, 2021, 10:43:48 pm
content: Strictly speaking, dB signifies the ratio of two power values: dB = 10 x log(P2/P1).However, it is common to assume (absent a specification to the contrary) that the impedance levels at the two measurement points are equal, giving the other common equation dB = 20 x log(V2/V1).The voltage ratio version is correct for equal impedance (e.g. 50 ohms). In a typical voltage amplifier, where the input impedance is high and the load impedance unknown, it is still a useful definition. So long as you use the same voltage measurement (rms, peak, peak-to-peak, etc.) for both voltages, the ratio is independent of the measurement type.Where things get interesting is with opto-electronics, where the output current is proportional to the input optical power, so a 3 dB reduction in light power gives a 6 dB reduction in output current.
Gain–bandwidth product of BC547 datasheet confusion - Page 1
Forum section: electronics / beginners

author: petert
author_rank: Regular Contributor
timestamp: November 16, 2020, 08:36:42 pm
content: When you look at thedatasheet from the BC547, the corresponding line reads:QuoteSorry if this is obvious, but what is now the GBWP (or fT), 100MHz or 300MHz? Why are there two frequencies?Since the GBWP (or fT) specifies the limit frequency that will still be amplified to unity gain, does it also mean I can switch frequencies up to fTwithout degradation/distortion? If it only applies to amplification, how do I know the maximum frequency I can switch?

author: TimFox
author_rank: Super Contributor
timestamp: November 16, 2020, 08:43:39 pm
content: That data sheet line means that the parameterftis measured at 100 MHz. I.e., the value ofhfeis guaranteed to be > 3 at 100 MHz.

author: petert
author_rank: Regular Contributor
timestamp: November 16, 2020, 11:24:56 pm
content: Thanks.What about this part?QuoteI mean switch, as in using a transistor as a switch.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 17, 2020, 01:30:31 am
content: Two problems:1. Switching is a large-signal process, so small-signal parameters (h_fe, f_T, etc.) aren't very meaningful. It's not that they're inapplicable, more that it's a hand-waving relationship; large-signal parameters can be measured in a similar way, but a more robust method must be employed to describe the nonlinear response. (Which isn't ever done with general purpose transistors, but is sometimes provided for RF power transistors -- the data are used in simulators that do harmonic balance and load pull calculations.)2. Switching is a wideband signal, and presumably you want it to look like it's switching, not just a pile of mush. So, you'll typically be below f_T / 10 say.Or put another way, expect the edge rate to be comparable to f_T, or a modest fraction of it (so, 1/3rd or ~100MHz or 10ns, for example), so whatever flat top/bottom you want inbetween needs to be as many times longer than that.And that's still pretty respectable, getting say 30MHz from a BC547. It won't look very sharp up there, but it can do it. Don't be stingy with the bias current, expect to need a good 10-30mA (and 0.5-3mA on whatever's driving the base) to do it.I've ran 2N3904s (basically the same thing, but 200mA) and 2N4401s (600mA) about as fast, and at about as much bias; I haven't done BC547 specifically, but it should be in that range as well.Tim
Galaxy S4 charger buzzing after unplug - Page 1
Forum section: electronics / beginners

author: Stonent
author_rank: Super Contributor
timestamp: July 02, 2014, 04:23:02 pm
content: Just wondering if it is normal for a smps to oscillate for about 30 seconds after being unplugged? It also buzzes just like this when plugged in and is somewhat annoying if I don't have the ceiling fan on as I hear it constantly.The charger is only a month or so old and came with a new phone.

author: Jeroen3
author_rank: Super Contributor
timestamp: July 02, 2014, 06:47:43 pm
content: Cheap smps might have coil whine for as long as the main filter cap has some juice.The only way to get rid of the coil whine is to change the load or the smps.

author: robimarko
author_rank: Regular Contributor
timestamp: July 03, 2014, 11:29:34 am
content: Yeah it simply coil,because there is no load and current draw.It will whine until main filter cap is not discharged

author: wraper
author_rank: Unknown
timestamp: July 03, 2014, 11:57:51 am
content: It might be a bad specimen as well. It doesn't mean that it is less reliable than usual, just may be that transformer coil or core is not fixed good enough. Worth to compare with another same model charger. As I understand Samsung provides 1 year warranty on chargers.

author: robimarko
author_rank: Regular Contributor
timestamp: July 03, 2014, 12:49:23 pm
content: It does not affect performance of charger,it is just annoying.Mostly they fix it by adding a lot of glue and strongly fixing it to the pcb.

author: amyk
author_rank: Super Contributor
timestamp: July 03, 2014, 12:50:08 pm
content: By "buzzing" do you mean mains hum or a high-pitched whine (sometimes with a bit of tick-tick-tick mixed in)? The former shouldn't occur with an SMPS, the latter is normal when unloaded since many of them will go into discontinuous mode.

author: Stonent
author_rank: Super Contributor
timestamp: July 03, 2014, 01:05:13 pm
content: To me it sounds about 60hz, but I could be wrong. It makes the same noise when plugged in. If I have time, I might try to capture the sound.It is possible it is higher than 60hz but the same note in a different octave.

author: tautech
author_rank: Super Contributor
timestamp: July 03, 2014, 01:26:59 pm
content: Quote from: Stonent on July 03, 2014, 01:05:13 pmYou could try winding a few turns on a piece of ferrite and connecting to your scope and read off the frequency counter.That should give clues to it's origin.

author: Stonent
author_rank: Super Contributor
timestamp: July 03, 2014, 03:11:16 pm
content: Yeah I was thinking about that. I don't have a frequency counter but can figure it out.

author: Shredhead
author_rank: Regular Contributor
timestamp: July 07, 2014, 02:52:06 am
content: I just got a galaxy note 3 and the charger cord is defective. My power supply for it makes no noise though. The only switching supplies I have that whine like that are the cheapest garbage on the planet. Send the piece of crap back while you still can for a new one.
GAMERS: IDEA: How about (diverting) an older 'Neuro-Network' Vision computer ? - Page 1
Forum section: electronics / beginners

author: RJSV
author_rank: Super Contributor
timestamp: March 30, 2022, 02:02:20 am
content: Hey, TESLA SELF DRIVING Computer features Neuro-net Vision chip.Since watching SHORT CIRCUIT testing a GPU, CPU, Gamer system, I'm wondering, that, since that sort of user has intense focus, on graphics performance, maybe some use has been made, of older or scrap system (out of a TESLA),...to enhance the graphical speeds ?The narrative quoting something like 4 Terra-Ops, per second. (Please see April 24 2021 posting, TESLA Self-Driving car, TECHNICAL CHAT section).That's got to be tempting, at those blistering rates.(I'm pretty much, as assembly language guy, pretty DUMB-ASS compared to a savvy Gamer...)Thanks.,Rick

author: RJSV
author_rank: Super Contributor
timestamp: March 30, 2022, 02:14:12 am
content: ...To view that older POST: (FSD) TESLA, see:Technical Section, approx page 31 (April 25, 2021 post). Discussion of computer and 'Neural Accelerator'

author: devinatkin
author_rank: Contributor
timestamp: March 30, 2022, 03:50:22 pm
content: If it's got a custom ASIC for handling vision I doubt the chip would do well repurposed as a GPU. I admit it would be neat to see someone try though.
"gangable" latching pushbutton switches - Page 1
Forum section: electronics / beginners

author: jdutky
author_rank: Regular Contributor
timestamp: December 11, 2020, 11:34:36 pm
content: I'm looking for pushbutton switches that can be "ganged" into sets of exclusive switches, so that when you push one switch in the set any of the others that are latched are forcibly released, like the preset buttons on an old-style car radio, but I can't seem to find anybody that makes these kinds of switches, even though I've seen them used in plenty of devices (well, maybe not plenty of modern devices, but I've found very similar modern multipole latching pushbutton switches, e.g. from E-Switch, but no mention of how to force the release of a latched switch).I figure that I just don't know what the right search terms are.Does anybody know what these switches are called, or what search terms I should be using?

author: Benta
author_rank: Super Contributor
timestamp: December 12, 2020, 12:09:39 am
content: You're looking for the ITT-Schadow series of pushbutton-array switches.They're supplied today by C&K and called the "F-series". It comprises not only the switches, but also caps, mounting rails, release mechanisms, springs etc.https://www.ckswitches.com/products/switches/product-details/Pushbutton/F/

author: bob91343
author_rank: Super Contributor
timestamp: December 12, 2020, 12:31:00 am
content: I have some of those switches in my junkbox. As a matter of fact today I searched for and found some but ended up with a different type, a lever switch with 3 positions. Now I have to make a bracket for it.
Ganging 12v SLAs: diodes to prevent "cross drain" - Page 1
Forum section: electronics / beginners

author: waoj
author_rank: Contributor
timestamp: March 22, 2023, 12:33:49 am
content: It seems to me that if you have a bank of batteries in parallel, and just one of them fails in 'the right way', it could ruin the value of the whole chain.Specifically, if one battery starts converting energy to heat, it will drain energy from the others faster than the trickle charger can keep up.I have a UPS in the basement who's batteries weren't lasting as long as I would like. And I had some spares at work, so I brought some home.None of them are particularly new. But my thought at the time was that if they were built to have 8AH, and were only performing 4AH of capacity today, that by adding another pair of similarly shitty 4AH batteries, I could achieve 8AH of total capacity.But instead, I noticed my runtime decrease even more (from 8 minutes to 4) And even after I undid my changes, it stayed around 4. Usage is low. I'm guessing around 100 watts to run a decent network switch and some wifi gear. It states 865 watts as "nominal", and current load 11 percentMaybe it's a coincidence. Or maybe I ruined my original cells by introducing other crappier cells. I let them acclimate for a few days before the first test, and recharge together before removing them and doing a second test without them.Is there a way I could use diodes to prevent this problem? Or (as I suspect) would any arrangement of diodes that prevented cross drain also prevent .... charging...My UPS is 24VDC internally, using two 12v SLAs in series. So I made a harness that extended two 10AWG wires out of the UPS to add externals. Though, now I'm thinking I want to just get a couple car batteries and replace these little SLAs for good. I wish the thing was 12v internally to be simpler.I also have an APC symmetra in storage but I worry it's own power consumption will cost more than a couple batteries each year. and it uses cartridges of 10x 12v SLAs, so that's a lot of money for essentially, a gamble, and its way overkill for the load I have. Even if I add a couple hundred watts putting the TV on it, its still overkill. I guess I need to shut up and go meter it out to know for sure though on the symmetra. But any chance I can use diodes to get the last bit of usefulness out of old SLAs.

author: james_s
author_rank: Super Contributor
timestamp: March 22, 2023, 04:23:42 am
content: If one of the batteries fails you should replace it. Adding diodes for isolation could work, but it will introduce additional losses. Even Schottky diodes will have a drop of a volt or more at high current.Car batteries are designed to supply very high current for a very short period for starting a car, they will not hold up well to UPS duty. What you want are deep cycle batteries, they're used often in boats and RVs and will tolerate that treatment much better. The tradeoff is the amp hour capacity is lower.

author: wasedadoc
author_rank: Super Contributor
timestamp: March 22, 2023, 01:55:35 pm
content: If you use diodes to isolate the batteries from each other they cannot be recharged by the UPS.
Garage Door Opener - excessive current? - Page 1
Forum section: electronics / beginners

author: Excavatoree
author_rank: Frequent Contributor
timestamp: April 05, 2024, 06:12:36 pm
content: I'm not familiar with this sort of calculation, so I'd appreciate someone letting me know if I'm "in the ballpark" here.My garage door opener uses a standard 9v battery, and I measured the current (not transmitting) at 13 µA.I couldn't find any discharge curves that low, but at 100 ma, the most batteries hit the cliff at about .35 ampere hours. (.30 - .45)So, at 13 µA, that's .35/.000013 = approximately 27,000 hours. That seems like a long time, and that my current draw isn't a problem, but I can't help but believe I've made a mistake.My other garage door opener's standby current is zero using the same meter, but it's a different brand. I'm not sure if that's relevant. It does make me think that 13 µA is too high.

author: voltsandjolts
author_rank: Unknown
timestamp: April 05, 2024, 06:23:09 pm
content: Yeh, agree with calcs.13uA is fine for a door opener transmitter when not transmitting.

author: PlainName
author_rank: Super Contributor
timestamp: April 05, 2024, 06:29:00 pm
content: QuoteSome don't connect the battery until you press the button, so standby current should be 0uA.

author: Zero999
author_rank: Super Contributor
timestamp: April 05, 2024, 07:42:17 pm
content: It should last for about 3 years whilst not being used, which seems reasonable to me.
garage door opener unknown communication method  - Page 1
Forum section: electronics / beginners

author: EvilGeniusSkis
author_rank: Regular Contributor
timestamp: November 22, 2014, 08:16:52 pm
content: If you look up the image you will see how the control panel is connected to the motor unit in my garage door opener 2 wires with 15VAC across them. the CP is "smart" is that it can tell you whether the safety beam is tripped, status of the battery backup and other things. it can also lockout the remotes and turn on the lights that are in the MMU as well as open/close the door. I am puzzled by how the CP communicates with the MMU as there are only 2 conductors running between them. as i don't have a scope i cant probe it. being 15VAC I cant use my arduino as a logic decoder. any ideas on how the CP & MMU are communicating?

author: Rerouter
author_rank: Super Contributor
timestamp: November 22, 2014, 08:37:39 pm
content: or could the motor unit be dumb, and have 2 limit switches, and a direction governing switch,power on, toggles direction switch, travels to limit switch, ,motor is locked out until power is next applied,revert back to the 15Vac leakage or minimum power for something, then when you need to send it the other way re-power it and the direction switch gets toggled again and away you go,If not the case, try measuring the voltage AC and DC when the motor is in motion, if it was some h bridged DC, then the AC would not change, but the DC would, in either AC or DC it is possible to AC-couple a serial signal, it just means you uses CRC on the end of the packet or similar to reject noise,

author: EvilGeniusSkis
author_rank: Regular Contributor
timestamp: November 22, 2014, 10:29:08 pm
content: the eyes for the safety beam and the backup battery (a 6V SLA) connect directly to the MMU so I'm pretty sure that there is some sort of coms between them. (the control panel indicates the state of the back up battery and the safety beam)the opener is a craftsman 139.18450D I can't find the manual online.

author: SeanB
author_rank: Super Contributor
timestamp: November 23, 2014, 09:19:27 am
content: They either use current pulses to convey data, by simply drawing high current pulses on the peak of the mains voltage so the MCU at the controller can send data to the MMU, and the MMU can signal by skipping voltage pulses as a signal method.Another method is to use a capacitor to couple an audio frequency data modulation onto the cable, and pick it off at the other end. Isolation at the supply side is easy as it has a choke in the transformer, and the controller just uses a in line choke to get the same isolation. This is likely what is used.
garden lighting standard or system? - Page 1
Forum section: electronics / beginners

author: alanambrose
author_rank: Frequent Contributor
timestamp: May 08, 2018, 07:57:23 pm
content: Hi,Is there a go-to garden lighting standard or system? I'm thinking something like a 24V ring around the garden and some kind of IP66 low voltage sockets to plug garden lights into?Alanp.s. I can see stuff like this:https://www.festive-lights.com/connectable-curtain-connector-10-ports#217=1079- but I was hoping for some kind of wall-mounted socket.

author: alanambrose
author_rank: Frequent Contributor
timestamp: May 08, 2018, 09:11:20 pm
content: Answering my own question here, but maybe something like this:https://uk.rs-online.com/web/p/industrial-power-connectors/6685379/

author: alanambrose
author_rank: Frequent Contributor
timestamp: May 09, 2018, 08:05:31 am
content: OK no takers: form anyone else in future, I think I'm going to use something like these:https://uk.rs-online.com/web/c/connectors/power-connectors/industrial-power-connectors/?redirect-relevancy-data=636F3D3126696E3D4931384E53656172636847656E65726963266C753D656E266D6D3D6D61746368616C6C7061727469616C26706D3D5E2E2A2426706F3D31333326736E3D592673723D52656469726563742673743D43415443485F414C4C5F44454641554C542673633D592677633D4E4F4E45267573743D69656320333039267374613D6965632033303926&r=f&sra=oss&applied-dimensions=4294803380,4291869342,4294427621,4294884955&sort-by=P_breakPrice1&sort-order=asc&pn=1

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 09, 2018, 07:09:51 pm
content: I got some run on 12VAC, the bulbs are standard push in maybe 2-3W each, only thing I can add is streets ahead of any solar system and robust but the plastic parts break after a few years/decades I guess from UV. Nothing hot-melt cant fix
Garmin Varia RTL515  - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: October 01, 2025, 01:45:58 pm
content: Anyone here who has any experience with Garmin Varia RTL515?The battery is charged to about 3.9V, and on a power supply I can see charging about 120mA, yet the green LED (that shows charging) is not seen?WHere to start with repair?

author: thm_w
author_rank: Super Contributor
timestamp: October 02, 2025, 11:21:50 pm
content: The battery is chargedviaa power supply? Or the battery is charging with the USB port?Take it apart, look for any signs of corrosion or water ingress first.

author: Jane
author_rank: Frequent Contributor
timestamp: October 03, 2025, 07:28:57 am
content: I used a laboratory power supply so that I could check current . I even tried to connect about 5V directly on plus and minus pins of USB connector on PCB.Yes, I took it apart but could not find any signs of corrosion on PCB under microscope?Any idea what to try next?Thank you for help

author: thm_w
author_rank: Super Contributor
timestamp: October 03, 2025, 10:28:35 pm
content: Didn't really answer the question, does it draw power on the USB connector or not?Maybe try unplugging and replugging the battery if that is possible, if you've already taken it apart.Not sure what this person is saying:https://thracium.net/en/crash-and-fix-radar-garmin-varia-rtl510
Gas Discharge Tubes  GDT - Page 1
Forum section: electronics / beginners

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 27, 2022, 02:01:31 pm
content: Does a GDT degrade over time or is degradation only related to number or magnitude of over voltage events?

author: Ian.M
author_rank: Super Contributor
timestamp: November 27, 2022, 03:03:07 pm
content: It depends - some older GDTs used a radioactive doped gas fill (or radium doped electrodes which emit traces of radon gas) to minimise dark effect. If the radioactive isotope used had a half-life of a few years, the breakover voltage of an antique N.O.S GDT may have increased significantly with age. However IIRC radioactive GDTs have been banned in most jurisdictions and most datasheets for recent and current parts will state the tube is made with non-radioactive materials.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 27, 2022, 04:15:24 pm
content: I don't know if GDTs are manufactured to avoid it, but neon tubes notoriously degrade over time and use, due to oxidation and other contamination of the electrodes, or dilution of the gas (which, usually the bulb is sealed fine, but if helium is used, it diffuses very slowly even through solid material). It's possible the same effect applies, but it can be alleviated (giving longer, if not unlimited, life) with proper manufacture.Also, needless to say, GDTs don't discharge very often, whereas neons can continuously. So it might be effectively irrelevant in practice -- if it lasts say millions of surges (or whatever the datasheet says), you're already well outlasting a MOV.Which is kind of a good reason to avoid a radioactive type anyway, if you need super long life equipment (20yr+). Just as well, eh?Tim

author: Terry Bites
author_rank: Super Contributor
timestamp: November 27, 2022, 05:30:01 pm
content: Read this:

author: TimFox
author_rank: Super Contributor
timestamp: November 27, 2022, 05:42:36 pm
content: Quote from: T3sl4co1l on November 27, 2022, 04:15:24 pmWith conventional neon indicator bulbs (NE-2, NE-51), my experience with degradation in continuous use was that metal from the electrodes sputtered to the interior surface of the glass, darkening the bulb.A bit of radioactive material was also used in some gas-discharge voltage-regulator tubes to ensure starting the discharge.An interesting list:https://www.royalsignals.org.uk/articles/radioactive-valves.pdf

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 28, 2022, 11:47:25 am
content: Thank you all for your comments. I was just thinking about a 145 Volt GDT as a protective device on a input circuit on a HP 3456. I suppose that with the essentially non triggering of the tube, it is not necessary to replace it. I also bought some NOS 145 Volt GDTs that are probably 20 yrs old. I suppose these are still good and will outlast me.I believe these are more modern tubes without the radioactive gas and that for this particular purpose, unless there is a leak the GDT is good.
Gas Sensors Detection - Page 1
Forum section: electronics / beginners

author: ameliaf03
author_rank: Newbie
timestamp: December 06, 2024, 07:19:56 am
content: I'm very new to electronics and i'm very confused on how LM 399 and the gas detection with green, yellow, and red light works if i have the supply voltage of 5V, please help and if you can explain in detail because im very slow and i really need your help.... thank you so much beforehand

author: pcprogrammer
author_rank: Super Contributor
timestamp: December 06, 2024, 07:59:17 am
content: What might help you is to first start with drawing a proper schematic instead of the wiring diagram you posted. You can, for instance, usehttps://easyeda.com/editorto draw it.Use the correct symbol for the different components. Like for the LM339 which houses four comparators use the triangle symbol shown in the datasheet.https://www.ti.com/lit/ds/symlink/lm339-n.pdfIf you still don't understand how it works after doing that come back here and post the schematic in this thread.

author: ameliaf03
author_rank: Newbie
timestamp: December 06, 2024, 08:24:33 am
content: thank youuu, i will try your suggestion first
Gate and Output Signal of MOSFET and Darlington Transistor. - Page 1
Forum section: electronics / beginners

author: hectorsr
author_rank: Newbie
timestamp: December 18, 2015, 02:30:01 am
content: Hi, collegues.This is my first time I'm working with an oscilloscope, and I know the basics about measurement but I want you to give me an advice.Firstly, I've got an MOSFET controlled by a IC, which I already know that sends PWM signals to the MOSFET's GATE I want to know: 1) Where should I connect the ground clip and measurement lead to measure the MOSFET's gate input signal? 2) Where should I connect the clip and lead to measure the DRAIN or SOURCE signals?Secondly, I've got an Operational Amplifier giving BASE signal to a Darlington Transistor. Again1) How should I connect the clip and lead to measure the Darlington's BASE signal and the COLLECTOR or EMITTER signals?I've attached the two circuit diagrams for you.Any advice will be welcomed.Thanks.

author: Delta
author_rank: Super Contributor
timestamp: December 18, 2015, 02:44:42 am
content: Erm, clip the ground lead to ground, then the probe to the gate (or source, or drain, or base, etc).

author: hectorsr
author_rank: Newbie
timestamp: December 18, 2015, 02:59:06 am
content: Thanks.What about the Operational Amplifier's circuit?

author: Delta
author_rank: Super Contributor
timestamp: December 18, 2015, 03:37:40 am
content: Quote from: hectorsr on December 18, 2015, 02:59:06 amGround clip to GND, probe to the base of the Darlo!I have a feeling you're really over thinking this mate!

author: Ian.M
author_rank: Super Contributor
timestamp: December 18, 2015, 04:42:01 am
content: http://www.eevblog.com/2012/05/18/eevblog-279-how-not-to-blow-up-your-oscilloscope/Never clip a scope's ground lead to anything other than a true ground node in the circuit, unless you are 100% certain the whole circuit is floating and doesn't have significant capacitance to earth or to the mains supply, in which case you can also clip to 'earthy' nodes of a floating circuit (which becomes non-floating (i.e grounded) as soon as you clip the lead on). Never clip ground leads to two different nodes of a circuit. Beware of other circuits and test equipment that may introduce a ground connection to a node that you do not expect.

author: hectorsr
author_rank: Newbie
timestamp: December 18, 2015, 09:13:30 am
content: You're right, Delta. I just wanted to be sure.Thanks all of you for your answers!!Peace.

author: Ian.M
author_rank: Super Contributor
timestamp: December 18, 2015, 09:26:22 am
content: It depends. If there's anything between the emitter or source and ground, you'll probably need a differential probe, though if its a very low resistance current sense resistor, you may get away wilt measuring with respect to ground.
Gate drive transformer simulation using LtSpice - Page 1
Forum section: electronics / beginners

author: Nilesh
author_rank: Contributor
timestamp: March 19, 2021, 04:09:39 pm
content: Hello everyone,Can someone help me with the simulation attached below?I'm trying to simulate gate drive buffer in LtSpice, but it seems the software doesn't want to run!!May I know where I'm going wrong?Thanks in advance!

author: StillTrying
author_rank: Super Contributor
timestamp: March 19, 2021, 04:47:06 pm
content: It doesn't like the 2 floating secondaries, connecting then to ground even through 1G resistors helps, and lower the simulation time to 1 or 2 ms.
Gate Driver as Amplifier? - Page 1
Forum section: electronics / beginners

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: July 04, 2018, 08:46:19 pm
content: Do I assume that a MOSFET driver is designed (internally biased) only to switch from a PWM signal and that if I have it a sine wave i’d Just get worse switching?In other words, it ain’t an amplifier?

author: owiecc
author_rank: Frequent Contributor
timestamp: July 04, 2018, 09:23:00 pm
content: Gate driver is basically a buffer with low output impedance. Some gate drivers are just two transistors, but most will have some additional control. If you apply a slow varying input signal you will probably get the same problems as any other digital logic connected to that signal. You may experience noise on the output close to the threshold voltage of your gate driver input. Other than that a sine wave should be ok. Do you have a specific gate driver in mind?

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: July 05, 2018, 12:45:34 am
content: Yeah, been looking at this one:https://www.mouser.co.uk/ProductDetail/634-SI8274AB1-IS1

author: Bassman59
author_rank: Super Contributor
timestamp: July 05, 2018, 01:13:40 am
content: Quote from: TheBaconWizard on July 05, 2018, 12:45:34 amThat part is designed to take logic inputs and do level translation (up to driver rail supply) and buffering for high output current. It has Schmitt trigger inputs so feeding it with a sine wave will just give you high-level outputs toggling at the input signal frequency.

author: b_force
author_rank: Super Contributor
timestamp: July 05, 2018, 09:14:08 am
content: You can use it as a Class-D type amplifier.