hybridfree/eevblog-posts huggingface dataset:
What TRIAC Firing angle to get equal step change in lamp brightness - Page 1
Forum section: electronics / beginners

author: eblc1388
author_rank: Frequent Contributor
timestamp: January 11, 2017, 10:02:15 am
content: A zero crossing detector is outputting a pulse every half cycle on zero crossing. This will be used to interrupt a MCU to change the firing angle of a TRIAC for an incandescent light bulb.If under MCU control, the firing angle can be set accurately to 5~175 degree electrically, what will be the value of firing angles say for N equal(roughtly) steps of brightness levels? e.g. N=16Thanks

author: capt bullshot
author_rank: Super Contributor
timestamp: January 11, 2017, 10:15:18 am
content: Quote from: eblc1388 on January 11, 2017, 10:02:15 amThis is a quite non-linear function. Easiest way to find your steps would be to determine them empirically. Build your circuit, use a simple table inside your code (which holds the angle values for the steps), fill it initially with a linear ramp. Then test your dimmer and change the table values to your best result. The result may vary with the type of the light bulb you use.And BTW: what exactly do you mean: equal steps? The human eye is highly non-linear in this term (kind of log function) ...

author: eblc1388
author_rank: Frequent Contributor
timestamp: January 11, 2017, 10:32:26 am
content: Quote from: capt bullshot on January 11, 2017, 10:15:18 amI meant equal preceived brightness steps as seen by human eye.Looks like I might try to assume brightness proportional to lamp power and starting from full power(P)/N, then work out the firing angle of 2*P/N, 3*P/N...etc. until I arrive at P.I searched the Web but couldn't find a graph giving lamp brightness vs firing angle. Maybe as you have said, it is different for different lamps.

author: Ian.M
author_rank: Super Contributor
timestamp: January 11, 2017, 10:34:13 am
content: More than you wanted to know about incandescent bulb physics:http://physlab.org/wp-content/uploads/2016/03/Planck_ref8.pdfIIRC the brightness is approximately proportional to the fifth power of the RMS voltage.
what type CLR meter is ok for my application? - Page 1
Forum section: electronics / beginners

author: tassos
author_rank: Newbie
timestamp: April 20, 2011, 03:34:32 pm
content: hello Davidis first time I sow your presentationfine workI will need your advice as I don’t have any were else to ask and it will be very kind of you to assistI am interested to be making coils for induction heating the power supply frequency generator operate on 25 khzI get the power supply from china company's and not able to work out with them good assistantsthe coil I will be making will be 50 uH, 80uH, 160uH and 180uH (micro Hunry) as the coils every time will be winded in pipes with deferent metal property's is very important to have a lcr meter to be measuring the coil to the appropriate uH every time as aboveI have seen a lcr meter appa 703 for 50% discount on eBay and price less than 200$ I have seen your extech lcr presentation video as well and cost of it in ebay 230$ . I was thinking as I am just starting and no much capital to go for a low cost as dm4070 close 34 $kindly I will need your advice as I am new on induction and no idea of what meter will do the job for as less as possible bat in the same time not throwing away money on something very bad quality not able to do the job (as well then country I am from economy is in very bad condition and money resources mast be very carefully handled )if I have to give you more detail of the project so you advice me properly on what meter to use kindly let me knowthanksTassos from Athens Greece

author: Ronnie
author_rank: Regular Contributor
timestamp: June 22, 2011, 12:41:55 am
content: Check Protek CL200 L/C meter price is $66.60 at Mouser Electronics. Resolution 1 µH, accuracy ±2% + 1 digit, though test frequency is only 900 Hz which is low compared to 25 kHz operating frequency.http://www.mouser.com/ProductDetail/Protek/CL200/?qs=sGAEpiMZZMv8kklI404QleuGRHl5VQMF
What type of cable is this? - Page 1
Forum section: electronics / beginners

author: sidlauskas
author_rank: Contributor
timestamp: August 06, 2019, 06:46:26 am
content: Hi,I need some help to identify this cable as I'm unable to find a replacement - it has in total 8 conductors, 1 pair is for power as wires are thicker and 1 pair is shielded (for Audio Left, Right and shield is for Audio GND).You can see in the picture that Yellow and White wires are shielded and rest of them aren't. Any ideas where I can get such a cable? Thanks

author: Jwillis
author_rank: Super Contributor
timestamp: August 08, 2019, 10:40:58 pm
content: Looks custom. At first I thought it may be an odd CCTV cable . But if its for audio /video a shielded multi core cable would probably work.I'm not an audio expert by any means maybe someone here might have something to add.

author: Nusa
author_rank: Super Contributor
timestamp: August 09, 2019, 12:13:58 am
content: If you can't find the exact replacement, getting one where all 8 conductors are the same size and shielded will certainly work, unless you need so much of it that cost is the issue. Having larger-than-required conductors for audio isn't going to hurt anything.If you only need ONE, buy individual lengths of what you need, bundle them and shrink-wrap the entire length. Two layers if one doesn't seem sturdy enough.
What type of capacitor is this one? an old one before 30 years ago or more! - Page 1
Forum section: electronics / beginners

author: HMS
author_rank: Contributor
timestamp: January 13, 2024, 12:42:23 pm
content: Anyone have an idea about this type of capacitor and its alternative nowadays or better? this is found inside an old 9V battery driven microphone and it is (0.068 uF).voltage is not clear, is the number 50 means volt ?is this type a polarized or non-polarized?Many thanks for your help.

author: wasedadoc
author_rank: Super Contributor
timestamp: January 13, 2024, 12:46:58 pm
content: Metal film, non-polarised. 68,000pF or 0.068uF. 50V.

author: HMS
author_rank: Contributor
timestamp: January 13, 2024, 01:05:48 pm
content: Quote from: wasedadoc on January 13, 2024, 12:46:58 pmthank you so much. that was very helpful.

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 13, 2024, 07:41:47 pm
content: Any film cap should do. If you want something better look at polypropylen (PP) type. They are quite miniature these days.Actually, it may be substituted by C0G/NP0 ceramic type too, it is quite achievable up to 0.1 uF.
What type of circuit will output 5V when a threshold is crossed? - Page 1
Forum section: electronics / beginners

author: Merlysys
author_rank: Regular Contributor
timestamp: March 03, 2014, 02:45:39 pm
content: Input peak is unknown, 0~20VOutput is to be 5V when the threshold is crossed. Threshold should be adjustable.Propagation delays, accuracy not important.Output goes to logic analyzer(LA) (since LA inputs must be <6V). Circuit is for preliminary investigation of commercially made equipment, laser printer scanner module in this case. I want to see where in the circuit changes occur so they can be examined more closely by oscilloscope.Is there an IC that will make several of these circuits at minimum size/cost? Best if 8+ points in the circuit can be examined by the LA simultaneously.Schmitt triggers is probably where I should start at, are there other types of IC based circuits? I looked into transistor based STs as I got lots of transistors lying around but they need several supporting components.Perhaps there is a completely different approach to this that I am missing.

author: madires
author_rank: Super Contributor
timestamp: March 03, 2014, 02:50:51 pm
content: I think you're looking for a comparator like LM339.

author: deth502
author_rank: Frequent Contributor
timestamp: March 03, 2014, 06:13:35 pm
content: yup, comparator.

author: Pillager
author_rank: Unknown
timestamp: March 03, 2014, 06:45:59 pm
content: I used a 7805 once for turning a 24V-high-signal to a 5V-high-signal. Been working for 3 years.

author: w2aew
author_rank: Super Contributor
timestamp: March 04, 2014, 12:37:11 am
content: Quote from: madires on March 03, 2014, 02:50:51 pmDitto on the LM339. With the open collector output, it's easy to get any high level you need.
What type of connector is this? - Page 1
Forum section: electronics / beginners

author: MentalFloss
author_rank: Contributor
timestamp: January 16, 2021, 12:28:11 pm
content: Does anyone know what type of connector this is? It's used on a boiler I'm working on. It's an 8 pin IDC edge connector that pushes onto the edge of a small pcb but it has to have the open ends like I've arrowed. Links to a page showing the part would be appreciated. Thanks.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 16, 2021, 02:29:43 pm
content: Looks like an AVX type edge connector or an AMP TE connectivity RAST type.

author: MentalFloss
author_rank: Contributor
timestamp: January 16, 2021, 02:58:32 pm
content: Quote from: Terry Bites on January 16, 2021, 02:29:43 pmThanks. Yes I think the AMP RAST might do the job, although it's not an exact copy.
What type of filter - Page 1
Forum section: electronics / beginners

author: harrysmith
author_rank: Contributor
timestamp: January 05, 2021, 10:07:02 am
content: Hi guyswhat is the type of filter and their cutoff frequency. thanks

author: bob91343
author_rank: Super Contributor
timestamp: January 05, 2021, 11:01:56 pm
content: They are not filters. They are traps or peaking circuits. The resonance of the L and C determines the resonant frequency and the R determines the bandwidth, or Q.Use the standard resonance equation and knowing the Q you can figure out the bandwidth.

author: opampsmoker
author_rank: Regular Contributor
timestamp: January 05, 2021, 11:49:28 pm
content: They certainly are traps or peaking circuits.But 1 is also a high-pass filter and 2 is low pass.Sub in the complex numbers and use the potential divider equation to find the frequency at whatever gain valueZc = 1/jwC or (0 - j/wC)ZL = jwL or (0 + jwL)ZR = R or (R+j0)Get excel to do it for you and sweep the frequency
What type of IC is this - Page 1
Forum section: electronics / beginners

author: alank2
author_rank: Super Contributor
timestamp: April 08, 2025, 09:26:01 pm
content: It is the BIOS I pulled from an old Leading Edge 8088 computer (2010E).the chip is labeled:9128ds-14112309700600GI 8752cda taiwanCan this be read in the minipro 866 ? If so what IC should I use to read it?

author: alank2
author_rank: Super Contributor
timestamp: April 08, 2025, 09:35:29 pm
content: I found this:https://electronics.stackexchange.com/questions/646502/looking-for-information-spec-sheet-on-an-old-prom-chip-gi-9128b-1180And was able to read it with 27128.
What type of inductor is this? - Page 1
Forum section: electronics / beginners

author: buffalo960
author_rank: Contributor
timestamp: July 14, 2011, 04:40:12 am
content: I have been looking for a while to find out what this symbol is but I cannot seem to find this exact symbol used anywhere else. Does anyone know?see attached

author: Armin_Balija
author_rank: Regular Contributor
timestamp: July 14, 2011, 06:00:43 am
content: I think that inductors with lines above them indicate a specific core? I'm not quite TOO sure what type of core that's referring to. I assume ferrite or iron?

author: 8086
author_rank: Super Contributor
timestamp: July 14, 2011, 06:05:56 am
content: It's an inductor with an iron core, rather than an air core.

author: saturation
author_rank: Super Contributor
timestamp: July 14, 2011, 06:23:07 am
content: Most likely magnetic core, with air gap:http://www.tracepartsonline.net/%28S%28thuv1ivh5bv4hqy4y5emrrnt%29%29/partdetails.aspx?PartID=10-01092010-085305&sk_Reference=&Class=SYMBOL_ELEC&ClsID=/SYMBOL_ELEC/SYMBOL_ELEC.110/SYMBOL_ELEC.110.030/&fwsid=
What type of mini usb connector it is? - Page 1
Forum section: electronics / beginners

author: xoom
author_rank: Regular Contributor
timestamp: January 06, 2017, 09:31:12 am
content: Can't find any part number or source where to get that connector.its from Garmin navigationif anyone know please give me a link or part number(not my photo)Thank you

author: Inflex
author_rank: Regular Contributor
timestamp: January 06, 2017, 10:00:42 am
content: Not quite it, but worth searching on eBay or AliExpress for things like "Garmin USB socket"http://www.ebay.com.au/itm/GARMIN-SatNav-Parts-Mini-USB-VERTICAL-socket-x-1-Piece-/232162963476?hash=item360dfdb014:g:HzgAAOSw4q9XTuV8

author: xoom
author_rank: Regular Contributor
timestamp: January 06, 2017, 10:06:53 am
content: already searched.. can find similar with pcb attached ..but wtf is this connector is it custom made by garmini thing i end up by soldering charger wires straight to pcb)

author: Inflex
author_rank: Regular Contributor
timestamp: January 06, 2017, 10:53:51 am
content: Quote from: xoom on January 06, 2017, 10:06:53 amMost definitely likely custom job, yes. If you can find something that still maintains the right socket positioning (for the casing) while soldered to the board with the pins, then you could at least just bodge it with silastic or epoxy in place of the mechanical holds / keys.

author: Koen
author_rank: Frequent Contributor
timestamp: January 06, 2017, 11:18:55 am
content: SUYIN 020200MA005XX56XXhttps://www.ecnmag.com/product-release/2011/11/robust-mini-b-usb-receptacle-serves-both-consumer-and-industrial-applicationsGood luck finding it !
What type of plug is it ? - Page 1
Forum section: electronics / beginners

author: alex-sh
author_rank: Regular Contributor
timestamp: August 14, 2024, 10:46:04 pm
content: Hello all,Silly question really but I cannot find any info.Could you please help me to identify a type of DC plug?Thanks

author: jonovid
author_rank: Super Contributor
timestamp: August 14, 2024, 10:58:38 pm
content: a property plug & socket standard when most common plug & socket standards will not do the job.deliberately made to be incompatible with common plug & socket standards.

author: themadhippy
author_rank: Super Contributor
timestamp: August 14, 2024, 11:23:18 pm
content: Looks like the socket used on those wall warts that come with 101 different plugs

author: alex-sh
author_rank: Regular Contributor
timestamp: August 14, 2024, 11:42:20 pm
content: Quote from: jonovid on August 14, 2024, 10:58:38 pmYou think this is a proprietary plug? However, it should still be possible to identify or find one?

author: alex-sh
author_rank: Regular Contributor
timestamp: August 14, 2024, 11:43:05 pm
content: Quote from: themadhippy on August 14, 2024, 11:23:18 pmNo, it is not. This is a 24V DC power supply plug for a turntable.

author: alex-sh
author_rank: Regular Contributor
timestamp: August 15, 2024, 12:26:27 pm
content: I found it.This plug is called “Texas plug”.I hope it helps if anyone has the same question
What type of transistor is this?  - Page 1
Forum section: electronics / beginners

author: Roverfan
author_rank: Contributor
timestamp: June 03, 2021, 12:31:07 pm
content: Hi, electronics newb here, I have managed to repair the board I was working on by replacing the transistor from a donor but would like to know what type of transistor this is.It is marked 1013, it shows 42v on input pin (pin 3?) and about 41.8v on pin (1?) and 0v on pin 2. When then on/off switch is pressed further down line of pin 1 and current flows it gives 42v on pin 2, so all pins are at full voltage.

author: gamalot
author_rank: Super Contributor
timestamp: June 03, 2021, 12:37:08 pm
content: 2SA1013http://www.unisonic.com.tw/datasheet/2SA1013.pdf

author: bob91343
author_rank: Super Contributor
timestamp: June 03, 2021, 06:05:39 pm
content: That is one of the strangest data sheets. Power dissipation in the hundreds of Watts, and curves unlike the usual plots one might see for a transistor.

author: Mr Evil
author_rank: Regular Contributor
timestamp: June 03, 2021, 06:58:40 pm
content: Quote from: bob91343 on June 03, 2021, 06:05:39 pmI would guess that there should be an "m" in front of those units. It doesn't inspire confidence in the rest of the data.

author: gamalot
author_rank: Super Contributor
timestamp: June 04, 2021, 04:48:29 am
content: Quote from: Mr Evil on June 03, 2021, 06:58:40 pmYes you are right, they should be 'mW; not 'W', You can find a lot of data sheets for 2SA1013 here:https://www.alldatasheet.com/view.jsp?Searchword=2sa1013%20pdf&gclid=Cj0KCQjw--GFBhDeARIsACH_kdZwxNmLTJFSDyFaHL000eJHnCrWGILquEZZ-c9ao99NEhv0dlb1JpsaAuf6EALw_wcB

author: HB9EVI
author_rank: Frequent Contributor
timestamp: June 04, 2021, 12:26:28 pm
content: as far as visible (Mouser, Digikey etc), the original 2SA1013 is long time obsolete and according to the Toshiba datasheet there wasn't any SOT89 version from their side either; so it's a china product with who knows what properties.
What value is this cap likely? - Page 1
Forum section: electronics / beginners

author: sonnytiger
author_rank: Frequent Contributor
timestamp: September 12, 2013, 11:36:42 pm
content: Those are the only markings on it (see picture), for scale, the long axis in the picture is about 1cm.

author: JDubU
author_rank: Frequent Contributor
timestamp: September 13, 2013, 12:01:34 am
content: My first guess would be a 12pF dipped silver mica capacitor.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: September 13, 2013, 12:03:51 am
content: Hi, its a 12pF (picofarrad) silver mica cap. plus minus 5% means J type (tolerance) .I`m not sure what the voltage should be ,i`d guess 100V .Edit: sorry DJubu ,posted at same time.
What Volt and time settings on my mini scope for 1996 Toyota Avalon Knock Sensor - Page 1
Forum section: electronics / beginners

author: serenitytek
author_rank: Newbie
timestamp: June 24, 2020, 08:33:02 am
content: Hi on my Quimat Updated 2.4" TFT Digital Oscilloscope Kit with Power Supply and BNC-Clip Cable Probe Q15001 mini scope how would I determine how to set the time and volt settings to find if my knock sensors are giving 7.2 kHz at 4000 rpm. Thanks

author: SparkyFX
author_rank: Frequent Contributor
timestamp: June 24, 2020, 11:39:48 am
content: Knock sensors are basically microphones, depending on technology you either need to supply power or not. You could test with any headset for starters.

author: serenitytek
author_rank: Newbie
timestamp: June 24, 2020, 12:30:33 pm
content: Thanks for your reply. I found the info I was needing.
what voltage can the HEF4093 work down to - Page 1
Forum section: electronics / beginners

author: Simon
author_rank: Unknown
timestamp: April 05, 2013, 09:26:55 pm
content: The datasheet keeps specifying parameters at 5, 10 and 15V but will it wok down to 3V ?

author: w2aew
author_rank: Super Contributor
timestamp: April 05, 2013, 09:33:31 pm
content: The datasheet shows a plot of input switching thresholds vs. supply voltage, and the curves only extend down to 4.5V VDD. So, I suspect that it might not work very well below that supply voltage. YMMV.

author: free_electron
author_rank: Super Contributor
timestamp: April 05, 2013, 11:12:58 pm
content: standard 4000 on 3 volt ...tricky.. depends on the manufacturer.4093 is a quad schmitt nand gate if i remember correctly. 74lvc132 should work.

author: SeanB
author_rank: Super Contributor
timestamp: April 06, 2013, 05:48:21 am
content: The quoted voltage range is 3-18V, but they are piss poor slow at 3V, basically you barely want to do more than 1kHz at most, as they are charging and discharging internal and external nodes at very low currents. In most cases the outputs are then barely able to sink 1mA, let alone source it.
What Voltage is used to calculated capacitor charge? - Page 1
Forum section: electronics / beginners

author: implor
author_rank: Regular Contributor
timestamp: November 24, 2019, 02:29:27 pm
content: Is there a standard that say what voltage to use when determine a capacitors capacitance?Example:you have a 1uF rated at 50V capacitors.is that 1uF at 50V?C = Q/V

author: Kleinstein
author_rank: Super Contributor
timestamp: November 24, 2019, 02:36:08 pm
content: In most cases capacitors are quite linear and it does not really matter which voltage to use.The normal way is to use a small voltage (like 1V) - so the same instrument can test all most capacitors.Especially with some MLCCs (class 2) however this can matter and the capacitance values given are for low voltage with no bias.

author: implor
author_rank: Regular Contributor
timestamp: November 24, 2019, 02:55:49 pm
content: Sound logical.the confusion is because i'm thinking of Capacitance as Energy but it's not.I was thinking about how using a high voltage rated capacitor would impact the amount of stored energy. Example 50V MLCC vs 25V MLCC (ignoring derating)But when I'm now doing some math I see it's only dependent on the accentual applied voltage and not the maximum rating.W = (C*V^2)/2Thanks for the reply
What voltage rating does SOIC and other packages have from pin to pin? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: October 30, 2023, 04:59:40 am
content: I can't find any spec listed, or any datasheet for the SOIC package. Is there a rating for what is the max voltage in a standard SOIC package from pin to pin? and other packages like DIP, and SIP which I presume would have the same rating as DIP right?The best I can find is ratings for DIP switches:https://www.mouser.com/datasheet/2/670/ds04_254_smt-1777718.pdfWhich it seems like they rate it at 500VAC form pin to pin.

author: magic
author_rank: Super Contributor
timestamp: October 30, 2023, 07:24:34 am
content: It will also depend on the PCB footprint, which is often wider than the pins themselves.High voltage parts in such packages (such as SMPS PWM controllers with built-in MOSFETs) typically use one pin in the corner for high voltage and then completely remove the pin next to it.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 30, 2023, 10:06:38 am
content: Depends on packaging material, and project regulations.IR21xx for example are available in SOIC-8 and claim 600V handling. Have also seen TSSOP/MSOP hot swap / load controllers rated say 100V.IC packaging resin may be considered to have a better than usual CTI (comparative tracking index); it's surprisingly rich in silica. Perhaps if arcing occurs, the organic binder burns away as much as it carbonizes?If it matters, you'd likely want to either:a) ask the manufacturer about the part ratings, standards met, and packaging material;ask the certification agency (i.e. UL, etc.) what they think about it;go back and forth until a suitable device has been selected; or,b) just get the SOIC-14 part with gaps (NC pins) included. Or parts with the pins removed (more common in offline SMPS controllers, I would say?).Tim

author: PartialDischarge
author_rank: Super Contributor
timestamp: October 30, 2023, 11:19:18 am
content: Quote from: ELS122 on October 30, 2023, 04:59:40 amI don't think they can claim 500VAC in between pins since this is an SMD component which should be mounted on a PCB so that voltage is dependant on substrate, humidity, etc. I've seen tracking occur at lower voltages in larger distances...Offline AC/DC converters have up to 800V mosfets in SOICs, but never pin-to-pin, *and* the board is usually routed with cutouts...

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 30, 2023, 12:06:37 pm
content: Simple, as stated by the device datasheet, if it says a pin supports 800V right next to a gnd pin, it does!Normally such devices come with layout recommendations.Plasma TVs Y-boards have 0.5mm pitch TQFPs drivers, IIRC handling 100-200V (These supplies are called VA, VS), generating high frequency ac signals, of course any dirt or moisture would cause arcing, but they're dipped in silicone.Still, strange to see that bunch of tight traces happy with it.
What wattage should this resistor be? - Page 1
Forum section: electronics / beginners

author: reddish75
author_rank: Regular Contributor
timestamp: May 28, 2025, 08:13:07 pm
content: Resistor R905 in this schematic is marked as a 270r 3W, what's in there looks quite large and im doubting the wattage on the schematic.Does 3W seem enough? How would I work this out?

author: mikerj
author_rank: Super Contributor
timestamp: May 28, 2025, 08:20:40 pm
content: R905 drops the 33.5v output from Q903 emitter to the 13.4v set by Zener D901. It therefore drops 33.5-13.4=20.1v, and the power it dissipates is V^2/R = 20.1^2/270 = 1.5Watts. A 3 watt part would seem quite a reasonable choice, though it will still be getting fairly warm.

author: TimFox
author_rank: Super Contributor
timestamp: May 28, 2025, 09:42:42 pm
content: A factor of two derating from the worst-case power is the old rule-of-thumb for resistor power rating.For TH parts, since I am conservative, I use a factor of four from the expected power value.(I was once burned by a wire-wound resistor running at full rated power, and still remember it.)

author: WattsThat
author_rank: Frequent Contributor
timestamp: May 29, 2025, 02:42:04 am
content: I don’t want to hijack the OP’s question but since it has been answered, I have question after looking at the schematic.What is the purpose/function of L901 in series with the zener D901?
QWERTY - Page 1
Forum section: electronics / beginners

author: pranav
author_rank: Contributor
timestamp: May 19, 2017, 03:02:48 pm
content: ...

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 19, 2017, 03:33:53 pm
content: buy another one and dont apply 12V again...

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2017, 03:36:12 pm
content: Most likely the laser diode was blown. There is not much else in these things electrically, just a very simple driver circuit but in some cases it's nothing more than a resistor.

author: bktemp
author_rank: Super Contributor
timestamp: May 19, 2017, 04:40:46 pm
content: Here is the circuit I have reverse engineered from a cheap identical looking green laser pointer I have bought around 10 years ago.It uses a simple current source with the forward voltage of the laser diode as a reference voltage.The current was somewhere around 200mA. If you apply 12V to this circuit, the transistor will overheat and fail short circuit. This will destroy the laser diode -> buy a new one.

author: pranav
author_rank: Contributor
timestamp: May 20, 2017, 02:52:03 am
content: Quote from: bktemp on May 19, 2017, 04:40:46 pmSo that means the module has completely destroyed?Sent from my Lenovo S850 using Tapatalk

author: james_s
author_rank: Super Contributor
timestamp: May 20, 2017, 03:02:56 am
content: Most likely. Nobody can say for sure without opening it up and measuring though.

author: jh15
author_rank: Frequent Contributor
timestamp: May 20, 2017, 03:56:23 am
content: Be careful with the one-hung-low brands with allegedly high power. Many will read high on a laser power meter, but is mostly infrared, and little green.Could put your eye out.NIST.gov has info on this.

author: ollihd
author_rank: Regular Contributor
timestamp: May 20, 2017, 02:37:33 pm
content: 90% sure that the laser diode is blown due to the "high" voltage. 2 options: 1. Buy a completely new pointer 2. Replace the blown laser diode.

author: james_s
author_rank: Super Contributor
timestamp: May 20, 2017, 03:13:38 pm
content: Replacing the diode is not really practical. Most green pointers are DPSS and the alignment of the pump diode is somewhat critical.
What will happen if I choose a 20W tip for a 60W solder iron? - Page 1
Forum section: electronics / beginners

author: rozeh
author_rank: Regular Contributor
timestamp: December 11, 2013, 12:57:01 pm
content: Hi everybodyI have a question for choosing a tip for solder iron.What will happen if I choose this tip:SMD goot 20W tipfor this solder iron?:BEST-813(60W)In your opinion, Is it a suitable choice?

author: rolycat
author_rank: Super Contributor
timestamp: December 11, 2013, 02:31:11 pm
content: From the pictures it's not clear whether that SMD tip is even physically compatible with the soldering iron, but it doesn't look promising.More importantly, a cheap 60W uncontrolled iron is not a suitable choice for electronics - it is likely to damage a lot of components. You need a temperature controlled soldering station for any serious work, SMD or otherwise. Dave has lots of useful advice on the subject in various blogs.

author: rozeh
author_rank: Regular Contributor
timestamp: December 11, 2013, 04:22:15 pm
content: I agree with you, rolycat. especially I think the many of these solder iron have problem. for example, they have electricity to its tips.

author: Robgo
author_rank: Newbie
timestamp: January 16, 2014, 06:49:02 am
content: Most new soldering irons nowadays are temperature regulated and ESD safe, you can consider Weller or ATTEN soldering tools.

author: lapm
author_rank: Frequent Contributor
timestamp: January 16, 2014, 07:41:12 am
content: Well my bet would be that you might ruin tips coating. after all 60 Watts is just 3x more then rated 20 Watts. And then theres matter of tips thermal mass. Because it has lower thermal mass is not designed to hande 60 Watts, temperature swings can be unexpectedly large. Heaters energy goes somewhere no matter what..Personally i would not recommend trying that just so save few bucks. Proper tip lasts long time with little bit care. Especially on hobbyist use.
What would be the best implement for an 'impossible to lose' remote camera - Page 1
Forum section: electronics / beginners

author: Musclor
author_rank: Contributor
timestamp: July 15, 2019, 03:04:25 am
content: I realize this may be a silly question, but I'm not finding answers anywhere and I have too many 'dead projects' lying around the house (the great lament of my wife haha).So, in a nutshell, I have a house which is like swiss cheese - I noticed very large (20/30cm wide) aircon ducts, weird false floors and false ceilings, and plenty of communicating spaces between floors. Honestly it's weird, every plumber/worker that comes over comment how odd the house is.I want to basically send a little rover in these spaces with a tiny camera on its back. I realize it's probably toy-like for most of you guys who are building planes for living or whatever, but hey, might as well ask the best! My concerns are:a) the little vehicle could get stuck and lost (and … see point about angry wife)b) the little vehicle could lose comms (less likely, but still, one never knows)So, instead of a vehicle (and vaguely remembering a team almost losing their cool worm-like explorer in the Egyptian pyramids), I've also been thinking about these very long fiber optics like camera you can get on AliExpress etc... but the problem is they are TOO flexible - they just pivot and have no grip to them. I need something I can maneuver and hold in position long enough to take pictures. And range. I need a lot of range.In an ideal world, I just wish to purchase the tool that would allow for this control - like a semi-flexible rod type thing, since I also would like to send a thermal camera in the netherworld of my cavernous home.In any case, it's just a little bit of fun and I wish you all a great day!

author: windsmurf
author_rank: Frequent Contributor
timestamp: July 15, 2019, 05:03:34 am
content: Maybe something like this?https://www.forbestusa.net/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=89&category_id=33&option=com_virtuemart&Itemid=212

author: Musclor
author_rank: Contributor
timestamp: July 15, 2019, 10:30:25 am
content: Thank you - looks safe - I guess I could lube the fiber in case I get worried about getting stuck somewhere? Certainly looks tons of fun, and potentially very useful too, as masonry work is always expensive to fix in a home like this (nevermind the neverending electricity bill from the giganto aircon ducts!).Thank you.
What would be the best way to limit current for an 80v DC circuit? - Page 1
Forum section: electronics / beginners

author: JohnBee
author_rank: Contributor
timestamp: December 18, 2017, 09:37:10 am
content: I'm working on small circuit that requires 80v DC with a current limit of 15 mA respectively.With that said, does anyone have any recommendations as to what the best method to limit the current with this particular voltage?I have used current limiting diodes in the past with good success, but the voltages were lower. However with 80v DC, the diodes cannot handle the wattage.Thanks in advance for any help you may have to offer on this.

author: danadak
author_rank: Super Contributor
timestamp: December 18, 2017, 11:15:00 am
content: Something like this -http://www.physics.unlv.edu/~bill/PHYS483/current_lim.pdfhttp://fritzing.org/media/fritzing-repo/projects/h/hotwire-foam-cutter/other_files/external%20current%20limiting%20circuit.pdfhttp://www.circuitstoday.com/controlled-transistor-series-regulator-with-overload-and-short-circuit-protectionRegards, Dana.

author: Zero999
author_rank: Super Contributor
timestamp: December 18, 2017, 02:39:34 pm
content: There's an error in your units: mAh is a unit of charge, not current. A battery charger circuit which delivers 7.5mA for two hours would be delivering 15mAh.How accurate does it need to be?What voltage is expected across the load?If you have 6V of headroom or more, then the LM317 can be used with a cascode on the pass transistor, to work at higher voltages than 40V. For 15mA, R1 = 82R and R2 can be much higher than 4k7, shown below: 47k will probably do. Tr1 needs to have a sufficient safe operating are to take 15mA, at 50V.
What would happen if a "4 wires energy meter" is used with a 3 phase device ?  - Page 1
Forum section: electronics / beginners

author: tigrou
author_rank: Regular Contributor
timestamp: March 31, 2024, 03:35:58 pm
content: I know there is two types of "3 phase energy meter" that exists : 4 wires (3 phases and 1 neutral) and 3 wires.I'm wondering if watts would still be counted correctly if a 3 phase device (eg: a 3 phase motor) is used on a 4 wires meter (thus ignoring neutral line).Does it depends if the 3 phases are balanced ?AFAIK : 4 wires meter get the voltage between each phase and neutral, then "multiply it" by current of each phase.3 wires meter get the current of two phases only, then multiply by voltage between that phase and the 3rd one (the one for which current is not monitored)Those schematics might help :

author: m k
author_rank: Super Contributor
timestamp: April 10, 2024, 07:51:48 pm
content: Meter doesn't know what it is metering.Triangle base, there's no potential difference.
What would happen if you connected 2 LiPo chargers (in parallel) to a LiPo batte - Page 1
Forum section: electronics / beginners

author: monster_of_electronics
author_rank: Contributor
timestamp: June 12, 2015, 02:01:03 am
content: Anyone? Would it charge twice as fast?

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 12, 2015, 04:34:41 am
content: NO. Atbest, it might charge slightly faster, but more likely at the "normal" speed.Atworst, overcharging the batteries can cause " overcharge, over-discharge, over-temperature, short circuit, crush and nail penetration may all result in a catastrophic failure, including the pouch rupturing, the electrolyte leaking, and fire." -- FAA Battery Incident Chart, includes incidents of Lithium-Polymer-Air ignition after puncturing. Ex: Entry for 11-Dec-2007

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 12, 2015, 05:20:58 am
content: Yes. The initial constant-current phase will go twice as fast. The CV phase will take as long; during that time, one charger may register as "done" while the other continues.It's not recommended, for the reasons listed above.Tim

author: lapm
author_rank: Frequent Contributor
timestamp: June 12, 2015, 07:11:30 am
content: Watch Daves video about lipo charging profile.. Watch it right now... There is very good reasons why charge is current limited...
What would you suggest to mount this sensor? - Page 1
Forum section: electronics / beginners

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 29, 2023, 08:49:53 pm
content: I would like to use this light sensor from Avago it's the APDS-9007. I like it because it has logarithmic output and I don't know how to inteface using I2C. However, should I just solder some wires to it or what kind of a board/support can I use? It's awkfully small and delicate.

author: MarkT
author_rank: Frequent Contributor
timestamp: December 30, 2023, 12:44:33 am
content: Looks like a custom breakout PCB might be the answer. Worth seeing if anyone sells this device already on a breakout board.

author: Jwillis
author_rank: Super Contributor
timestamp: December 30, 2023, 01:47:02 am
content: You can get these kits.SMD Protoboard. Their are others as well.They have a variety SMD foot prints that could fit your needs if your not worried about a little extra unused board. You can solder wires or used header pins.Another way is a piece of single sided copper clad and grind away the copper to make your own breakout board.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 30, 2023, 11:19:09 am
content: Attached image shows the pin layout. Only the 4 corners are used.That looks custom. Center to center on the narrow dimension is 1.4 mm and wider is 2 mm. A custom board (BOB) is probably the simplest. You might be able to solder fine wires directly. If I just needed one for testing I would check first what BOB's I had, then make something from a piece of copper clad perfboard. I have a small ( MicroMark) table saw with carbide blade. I use it to remove copper in nice, straight strips.
What's a PTC device? The acronym stands for "positive temperature coefficient". - Page 1
Forum section: electronics / beginners

author: ModernRonin
author_rank: Contributor
timestamp: June 17, 2010, 04:57:46 am
content: I didn't know, and maybe other people don't either.Basically it's a little device that heats up very quickly when too much current flows through it, and increases its resistance in a non-linear fashion due to heating, thus cutting off surges of current.http://www.circuitprotection.com/catalog/fundamentals/PSWFundamentals.pdf

author: Zero999
author_rank: Super Contributor
timestamp: June 17, 2010, 11:53:05 am
content: Useful guide.Another common name is polyswitch or polyfuse.THey can also be used for overtemperature protection in transformers and motors.

author: Pyr0Beast
author_rank: Contributor
timestamp: June 26, 2010, 10:39:15 am
content: Poly-switch is more like a resettable fuse than a true PTC element by my standards, tho they are very much alike.

author: Zero999
author_rank: Super Contributor
timestamp: June 27, 2010, 01:33:55 pm
content: They're so alike because they're the same thing.

author: Unknown
author_rank: Unknown
timestamp: June 27, 2010, 02:55:56 pm
content: Not really. PTC (positive temperature coefficient) is just about the tempco, the opposite of NTC. PTC resettable fuses/polyswitches/polyfuses do have a positive tempco, but the resistance sharply increases above a certain temperature. At that temperature something inside melts, and they trip (though a small amount of current keeps flowing). After they're tripped, they'll be slower to trip next time. There are also PTC thermistors designed as temperature sensors, these have a linear(ish) resistance versus temperature curve, and don't change when exceeding a certain temperature. These can survive much more heating/cooling cycles. Regular resistors can also be classified into NTC and PTC (eg. carbon film versus metal film).

author: Zero999
author_rank: Super Contributor
timestamp: June 27, 2010, 08:36:55 pm
content: I suppose you're right, all polyswitches are PTCs but not all PTCs are polyfuses, the temperature vs resistance characteristic needs to have an sudden enough change at a certain temperature to act as a fuse.
What's an interesting, Simple Bluetooth Low Energy Project for a Beginner? - Page 1
Forum section: electronics / beginners

author: monster_of_electronics
author_rank: Contributor
timestamp: November 04, 2015, 07:38:42 am
content: Are there any? Beginner in electronics...I've taken a circuits 1 course, electronics documentation, intro electronics fabrication, some digital basics, some other fundamental courses and tinkered around doing basic repairs but don't really know what I'm doing yet. But the applications of BLE fascinate me...PS: I have ADD (truly diagnosed, and not the hyperactive type) so I always gravitate toward application first.
What's happening with this non-inverting amp? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: May 09, 2015, 09:14:36 pm
content: Here' a beginner OpAmp question.First of all.YES I KNOWthe V- connection of the OpAmp really should be connected to -5V and not ground but THAT'S the point of this question.Theinverting ampdoes as I'd expect and the blue trace stays at zero when the input (green trace) is positive.Thenon-inverting amp, on the other hand, is fine up until the input goes beyond about -0.7V then you get those huge spikes where I'd expect it to stay at zero.What's happening here when the opamp is poweredincorrectlythis way?

author: c4757p
author_rank: Super Contributor
timestamp: May 09, 2015, 09:35:33 pm
content: Phase inversion. You're saturating the input transistors, so they no longer behave as inverting differential amplifiers and begin passing the signal through directly - so in effect, the op amp's inputs swap.

author: dentaku
author_rank: Frequent Contributor
timestamp: May 09, 2015, 10:53:30 pm
content: Quote from: c4757p on May 09, 2015, 09:35:33 pmSo... looking at the internals of an LM358 I see that the inputs are connected to PNPs so when the input goes to about -0.65V below GND that's when saturation happens?Hmmm... Isn't 0.6 to 0.7V a typical diode drop too?

author: Andy Watson
author_rank: Super Contributor
timestamp: May 09, 2015, 11:09:35 pm
content: Quote from: dentaku on May 09, 2015, 10:53:30 pmYes, it is not a coincidence.
What's inside a dishwasher turbidity sensor? - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: June 21, 2016, 07:20:02 am
content: For example,http://imgs.inkfrog.com/pix/usedapplianceparts/635_KITCHENAID_WHIRLPOOL_KENMORE_Dishwasher__W10134058.JPGI'm interested because these things are way cheaper than lab grade sensors. The application I had in mind is detecting algal blooms in water.I haven't found any pictures that show the internal circuit board of this particular sensor type. It looks like there are 3 optical elements but I've also seen simpler (perhaps older) designs that just look like a larger version of a slot photo interrupter.Do the newer designs measure the amount of side scattering similar to the way lab grade sensors work?Mike

author: Signal32
author_rank: Frequent Contributor
timestamp: June 21, 2016, 07:51:23 am
content: See below for what the one you linked looks like inside.I'm not sure how it works, probably not much different than the older one. Best guess is that it works the same but with an added sensor to measure scattered light.The older one seems to be only a LED + Photodiode.The price difference could be that this does not include any controller/logic, all of it being built into the dishwasher.

author: e100
author_rank: Frequent Contributor
timestamp: June 21, 2016, 08:08:49 am
content: In the last image, is the black blob a light stop, or is it directing the unscattered light down to the endmost sensor?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 21, 2016, 08:14:46 am
content: The black looks like the normal IR-pass filtering plastic package of a photodiode

author: e100
author_rank: Frequent Contributor
timestamp: June 21, 2016, 08:33:06 am
content: The black photodiode glued into the housing?Perhaps the PCB in the top picture had to be ripped out leaving the photodiode behind?So perhaps a in-line photo-interrupter to sense large bits of food debris and a receiver(s) at 90 degrees for the smaller particles scattering light?Does that sound reasonable?
What's next for Rigol after the 1054Z? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: September 26, 2016, 02:03:50 pm
content: I know scopes aren't like phones that keep being updated every year but companies like Rigol seem to put out new stuff quite regularly.After the success of the 1054Z I wonder what's next? Is there maybe something new one the way soon in the same price range? I'm not sure how long they waited between releasing the 1052 and the 1054.I know the company isn't going to tell everyone what they're working on but I'm just wondering what more knowledgeable people on the forum think?

author: nowlan
author_rank: Frequent Contributor
timestamp: September 26, 2016, 03:12:02 pm
content: Is just 2 years old. Sep 2014.

author: jitter
author_rank: Frequent Contributor
timestamp: September 26, 2016, 04:19:27 pm
content: Quote from: dentaku on September 26, 2016, 02:03:50 pmRough guess: about six years between the 1052 and the 1054. Unless the competition starts to do better for less money and it starts losing Rigol customers, I don't think we'll see a new version soon.

author: dentaku
author_rank: Frequent Contributor
timestamp: September 26, 2016, 11:56:58 pm
content: Quote from: nowlan on September 26, 2016, 03:12:02 pmIt's not as old I thought.
What's the difference between BC547/BC547A/BC547B/BC547C? - Page 1
Forum section: electronics / beginners

author: sonic
author_rank: Regular Contributor
timestamp: October 31, 2013, 12:59:21 pm
content: Hi!I'm trying to control a flash with a headphone out using this circuit:I hope the 2k2 resistors that I already have will also work.After ordering 50 BC547Cs, it occured to me that there are 4 varieties with different hFE:VarietyMinMax547110800547A110220547B200450547C420800What's behind this?How can the variety BC547 span the range of all the others?Does all that matter for this circuit?

author: Simon
author_rank: Unknown
timestamp: October 31, 2013, 01:01:23 pm
content: just make sure the resistors are the right value to acount for the lowest gain you may have.the letters after the part numbers can often mean different CE voltages

author: kayvee
author_rank: Regular Contributor
timestamp: October 31, 2013, 01:15:39 pm
content: The 547 is the non-graded version, whereas the A, B and C versions have been graded into specific hfe ranges.

author: sonic
author_rank: Regular Contributor
timestamp: October 31, 2013, 01:32:48 pm
content: VCE= 4.8 VIC= 1.6 mA

author: SeanB
author_rank: Super Contributor
timestamp: October 31, 2013, 07:01:42 pm
content: Basically any of them will work there. The ungraded one is just tested on the line ( hopefully) and is not graded, or is the selection that is out of either the top or bottom gain selections so may work perfectly or not at all. This is often the case that the cheapest components like transistors are not tested fully during manufacture, just are done on a sample basis. The A,B,C ones have had a simple gain test during production and are binned into the 3 grades as they test out. Often the cheapest is not the lowest gain but typically the mid, where the processing places most of the devices.The reason why you might want a gain group is that some circuits need a gain in a certain range to operate correctly, and ones with too high or too low a gain may not operate properly over the full operating condition range, or may saturate near full signal level.