hybridfree/eevblog-posts huggingface dataset:
Single to split rail converter current draw - Page 1
Forum section: electronics / projects

author: XTEC
author_rank: Contributor
timestamp: March 27, 2024, 02:29:29 pm
content: Hi. I'm building a mic pre-amp, and require a split rail from a single rail 12v supply. So I'm using a typical op-amp virtual ground circuit, with a TL071 and a couple small BJT's. My pre-amp circuit will only draw about 20mA standard, worst case <100mA if the output is shorted.I get a nice clean +5v / -5v with reference to the virtual ground... except the current consumption is huge! The shown circuit is drawing about 100mA with no load. Adding a load makes the current increase as expected (ie; add 10mA load makes the total current consumption 110mA). Needless to say the transistors and regulator are cookin'! Any idea why so much current? We did find one error on the PCB, but have corrected that and installed all new components, and still this big current draw.I modelled this in LTSpice, and I get nowhere near this sort of current. Hummm....Would much appreciate any suggestions, insight or education anyone can provide. Thank you in advance!EDIT: Added PCB layout. Q3 collector and emitter are backwards, we have bodged this on PCB for now.

author: XTEC
author_rank: Contributor
timestamp: April 06, 2024, 02:49:18 pm
content: This never got a comment, but FYI for anyone in future:Turns out the op-amp was self-oscillating. Seehttps://electronics.stackexchange.com/questions/557532/why-is-this-buffered-rail-splitter-oscillating-and-how-can-i-compensate-itWe added the 10nF cap between output and inverting input, and a 2K4 resistor in the feedback loop, and now it runs well.

author: XTEC
author_rank: Contributor
timestamp: April 06, 2024, 02:52:24 pm
content: This:

author: MarkT
author_rank: Frequent Contributor
timestamp: April 06, 2024, 08:43:13 pm
content: The resistor normally goes between the opamp output and transistor emitters, which then act as current dumpers. A much better circuit is to use a proper current buffer in place of those transistors, or at least to bias them to class B rather than class C as they were in your original circuit.

author: Zero999
author_rank: Super Contributor
timestamp: April 06, 2024, 09:51:06 pm
content: + 1 regarding the resistor in between the op-amp's output and the emitters of the transistors.That's hardly surprising. Are you even sure you need C1 and C2? I would just put them across R1 and R2.

author: Smokey
author_rank: Super Contributor
timestamp: April 06, 2024, 11:20:10 pm
content: I'm not sure if this is relevant here, but higher current "rail splitters" are probably classAB amplifiers and they will always have some quiescent current due to biasing. The more bias current the lower the crossover distortion will be so sometimes they set it higher than you would expect.
Sinotimer MC701 temperature controller help required. - Page 1
Forum section: electronics / projects

author: Another Dave
author_rank: Contributor
timestamp: May 09, 2024, 01:17:34 pm
content: Hoping someone can help where the manual lets me down.I purchased the Sinotimer MC701 which I thought had the brilliant option of Relay and SSR output. This will be used withvarious heating appliances some going upto as little as 105ºC and some as high as 1300ºC.Housed in a box with external sockets I was setting it up and whilst dropping the output down to 2 seconds for the SSR therelay kept clicking at the same time, thinking it was the alarm I disabled those but still the clicking and then it hit me thatthe clicking was the output relay which it seems to energise the same time as the SSR.So setting it to 2 seconds will probably cause a rapid relay failure? Setting it to 20 seconds maybe a little too wide on the temperaturescale when dealing with clays for jewellery and/or low temperature enamels where a stable temperature is more important thanthe lifespan of the relay.Typically my old MYPIN TA4-SNR died just before I needed to make some stuff so needed something fast.Anyone have any experience of the MC101 series temperature controllers? Is it possible to disable the relay output and use onlythe SSR?It's the Sinotimer (MC701)Thanks.
SIP-21 package dimensions? - Page 1
Forum section: electronics / projects

author: somlioy
author_rank: Regular Contributor
timestamp: May 16, 2012, 07:14:44 pm
content: HiI need to make a component package for SLA7062M which is a SIP-21 package, and I can't seem to understand the dimensions from the datasheet. Can anyone tell me how much space there's between the pins?SLA7062M

author: baljemmett
author_rank: Unknown
timestamp: May 16, 2012, 07:46:54 pm
content: Quote from: somlioy on May 16, 2012, 07:14:44 pm1.43mm (+/- 0.5mm) between adjacent pin centres, but since they're staggered to each side it's double that between two pins in the same row (with 4mm +/- 0.7mm between the rows). The relevant dimension is the one labelled "20xP1.43+/0.5=28.6+/-1" -- 21 pins gives 20 inter-pin intervals, times the pitch of 1.43mm.

author: mariush
author_rank: Super Contributor
timestamp: May 16, 2012, 07:52:32 pm
content: Like the post above... 1.43 mm between pins... so ~ 2.85 mm between two pins on the same side. 4mm +/- 0.7 between the two rows of pins.There's a board made with this chip here:http://www.piclist.com/techref/io/stepper/SLAm/SLAm_bld.htmLots of pictures and schematics and details.

author: somlioy
author_rank: Regular Contributor
timestamp: May 16, 2012, 08:41:33 pm
content: Alright, thanks alot guys.
SIP enclosure for encapsulating - where and how? - Page 1
Forum section: electronics / projects

author: OleMi
author_rank: Contributor
timestamp: January 18, 2021, 10:28:26 pm
content: We are designing a module to be encapsulated to SIP7 packaging with 5 pins. I am trying to find a manufacturer of SIP enclosures or a subcontractor for encapsulating part of the job, but neither Google nor Alibaba will help. Looks like each manufacturer of SIP-encapsulated modules do their own molds. Does anyone know where to source such enclosures?Another question is about pins for such packages. They don't look as a regular pin-headers. Does anyone know if this is a standard part?

author: tszaboo
author_rank: Super Contributor
timestamp: January 18, 2021, 10:31:49 pm
content: Those small modules are not encapsulated in an enclosure. They use potting with a mould. While it sound expensive, I've worked with suppliers that only charged a few hundred EUR setup cost for such a mould.Otherwise the search term is "potting box"Those pins: Mac8, mill-max and others will have those parts.
SIP PCB Connectors - Page 1
Forum section: electronics / projects

author: GingGangGooly
author_rank: Contributor
timestamp: October 07, 2013, 02:15:10 pm
content: Hi allI am trying to source either the name or a supplier of the SIP PCB pins which are used by Capital Advanced on their SMD adaptors; which they call 'Uni-SIP'http://www.capitaladvanced.com/us1000.htmThis image shows the PCB pins I am trying to sourceFarnell sell the whole adaptors (rather expensive for my taste), but I can't find the PCB pins, I have tried Farnell, RS, Mouser, Digi-key etc. It may be I have not used the right name, or these are parts specific to Capital Advanced.Any help would be much appreciated.Cheers

author: Capital
author_rank: Newbie
timestamp: October 07, 2013, 04:37:43 pm
content: This part is available from Digi-Key. Search their web site with this "pin SP-1A" and you will see the pins available in reels of 1000.

author: GingGangGooly
author_rank: Contributor
timestamp: October 07, 2013, 05:32:54 pm
content: Thanks for the quick reply & pointer to what they are called.I will have to search for somebody who sells them as either 100 or 200 as 1000 is too many for me.Cheers

author: Capital
author_rank: Newbie
timestamp: October 07, 2013, 05:55:00 pm
content: Try Alltronics, I think they sell smaller quantities.
SIPM power supply - Page 1
Forum section: electronics / projects

author: arivel
author_rank: Regular Contributor
timestamp: August 12, 2024, 04:02:04 pm
content: hello everyone.I need a power supply for SIPM. It is not easy to find, there would be HV80B but combined with the PCB board it becomes expensive.here is the link with specifications:https://www.hamamatsu.com/content/dam/hamamatsu-photonics/sites/documents/99_SALES_LIBRARY/ssd/s13360_series_kapd1052e.pdfmuch better a ripple below 0.5mV and an adjustable voltage that reaches 80 volts.can you recommend me?.thanks.
SISTEMA: Safety Integrity Software tool for help achieving ISO 13849-1 - Page 1
Forum section: electronics / projects

author: 1sciguy
author_rank: Contributor
timestamp: August 18, 2022, 07:09:15 pm
content: Is anyone here using SISTEMA and designing safety products that need to meet a certain performance level of ISO 13849-1? I'm just getting into the software and watched the YouTube tutorial, but I can't seem to find any forums dedicated to Q&A. Was hoping maybe people here have used it. In particular, I know that the standard allows the use of non-safety rated components to form a safety compliant system to a certain performance level if proper engineering practices and redundancy are used. After all, the guys that sell the red painted "Safety Relays" for $200 each had to start somewhere by building a feedback monitoring circuit around a pair of $5 force-guided relays.https://youtu.be/j05BRNmRaGc
Site to check stock among many distributors - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 24, 2020, 07:47:32 am
content: I had a site called ECIA in my bookmarks, I remember using it to quickly find and compare pricing, stock, lead time, etcThe URL ishttps://www.eciaauthorized.com/enbut this now redirects tohttps://www.trustedparts.com/enIs it really to be trusted? It looks different but seems to be the same functionality. Anyone using the new site, is it legit?When did it change?

author: JackJones
author_rank: Regular Contributor
timestamp: September 24, 2020, 07:58:35 am
content: Found this with waybackmachine:Quotehttps://web.archive.org/web/20200509174018/www.eciaauthorized.com/enNo idea about the trustworthiness.An alternative would be octopart.com.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 24, 2020, 08:06:22 am
content: Duh! Thanks. That's about when I stopped using it.

author: exe
author_rank: Unknown
timestamp: September 24, 2020, 08:27:41 am
content: I use octoparts.
Six Axis Robotic Arm - Page 1
Forum section: electronics / projects

author: Alberto
author_rank: Regular Contributor
timestamp: May 22, 2015, 06:42:41 pm
content: Hi!I thought I would start by introducing myself as this is my first post on the EEV Blog forum. I'm a 17 year old A Level Student from the UK currently studying Physics, Maths, Further Maths and Systems and Control. I really enjoy electronics, and hope to become an engineer one day (possibly systems or electronic engineering). I have been watching EEV Blog for a while now, I've learnt a lot from Dave already!Anyway, onto the main topic of this thread. For this years Systems Project I made a 6 Axis Robotic Arm. It's driven by Seven Servo Motors and has a claw for grabbing, although one day I would like to put a suction cup mechanism on the end. Here's a link to a build video:I also made a few posts on my blog about it:http://rctalesofarookie.weebly.com/I did some pretty cool things with it, such as design and 3D Print a claw for it. I hope to use it as a tool for experimenting with other electronics in the future.There is a chance some of you may have seen a post about this on another forum, however the project is now done! I ended up getting full marks on my coursework for it, so far so good!Thanks all!Alberto
Six-Channel Opto Couplers - Page 1
Forum section: electronics / projects

author: German_EE
author_rank: Super Contributor
timestamp: August 27, 2014, 09:25:27 am
content: I've seen various sorts of opto-coupler over the years and they have varied from a single channel in a four pin package to four channels in a sixteen pin DIP. So, a question for you all:Does anyone make a device with six opto-coupled channels in a single package? Surface mount or through-hole, I do not care. Isolation needs to be 400 V AC or better.So far I have tried Mouser, Digikey, RS, Farnell and all of the German component distributors without success.

author: mzzj
author_rank: Super Contributor
timestamp: August 27, 2014, 10:05:49 am
content: If it is not availlable its probably bad idea to use it in your design.Csm170 would be 8-channel opto with all the availlability and pricing problems...

author: H.O
author_rank: Frequent Contributor
timestamp: August 27, 2014, 10:21:33 am
content: What's the application? Does the isolation barier have to be optical?Depending on the application you might (or might not) be able use something like the ADUM7604 or the SI8660. Search Digikey fordigital isolators.

author: dannyf
author_rank: Super Contributor
timestamp: August 27, 2014, 10:43:57 am
content: QuoteDoes it have to be in a single package? If not, it is trivial to make one from multiple singles/dual/quad.

author: David Hess
author_rank: Super Contributor
timestamp: August 27, 2014, 03:39:37 pm
content: Quote from: dannyf on August 27, 2014, 10:43:57 amIt will be less expensive as well will not take up significantly more space.

author: German_EE
author_rank: Super Contributor
timestamp: August 28, 2014, 10:12:06 am
content: Ah! Thank you to H.O for the tip about digital isolators. This is a technology which I have not encountered before but it is however just what I need.
Sizes of DC Power Sockets (Barrel Connectors)  - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: April 18, 2020, 03:03:32 pm
content: Hi,there are many sizes of DC Power Sockets (Barrel Connectors) used by most DC wall power adaptors. I haven't yet found a logic nor a standard behind the various sizes (attached is my list of just Switchcraft parts). Furthermore in practice I found that some sockets can accept at least 2 sizes of the mating (cable) connector and still work.1) Can anybody provide any logic at least on which one to choose?2) Which is the most commonsocketgenerally as well as in USA and Europe? Alternatively a "preferred" one and for what reason would that be a preferred choice?3) any general/other guidelines or infos also much appreciated.Many thanks

author: magic
author_rank: Super Contributor
timestamp: April 18, 2020, 05:37:32 pm
content: In my experience most devices which don't care about high current (like laptops) or small size (like cameras) tend to use either 2.1/5.5mm or 2.5/5.5mm. These dimensions refer to the inner/outer diameter of the female plug. There is also some variation in the length of the plug

author: oPossum
author_rank: Super Contributor
timestamp: April 18, 2020, 06:32:53 pm
content: Take a look at what power supplies are available for your application and what plug they come with. For 6 volts and higher this will typically be 2.1 or 2.5 ID and 5.0 or 5.5 OD (4 possibilities). For 5 VDC 1.35 ID / 3.5 OD is somewhat of a standard. It is used on USB hubs and small external hard drives.

author: ricko_uk
author_rank: Super Contributor
timestamp: April 18, 2020, 11:37:52 pm
content: Thank you all!!

author: magic
author_rank: Super Contributor
timestamp: April 19, 2020, 05:10:42 am
content: And if you want to piss your customers off, find one of those obscure PSUs which are center negative

author: james_s
author_rank: Super Contributor
timestamp: April 19, 2020, 06:39:59 am
content: I hate the 2.5mm center pin ones, they're much less common so I always have to really dig when I find something that needs one. While there's no standard, it does seem to be used more often for AC output power adapters.

author: analogo
author_rank: Regular Contributor
timestamp: April 19, 2020, 07:49:06 am
content: No suggestion, but a bit of extra info.The reference standard for these connectors is IEC 60130-10. You may find more information under that name.Lots of musical equipment (for example guitar pedals) has standardized on 5.5/2.1Another dimension to think about is the length of the barrel, not just the OD/ID.
Sizing of resistors in LED strips - Page 1
Forum section: electronics / projects

author: ivonenand
author_rank: Contributor
timestamp: September 13, 2020, 07:16:47 pm
content: Hi Guys,For me, sizing the resistors for LEDs was always a trivial task, until now. I have a 24V DC power supply, coming from a MeanWell AC/DC brick, and I need to power white LEDs from this 24V. The white LEDs are in 2835 housing I need to run about 50mA through them; at that voltage they have about 2.85V. So now comes the question, how many LEDs can I put in series, or to put it differently, what % of those 24V should I reserve for the resistors? I have the following options:8 LEDs in series: 22.80V on LEDs, 24 Ohm resistor7 LEDs in series: 19.95V on LEDs, 81 Ohm resistor6 LEDs in series: 17.10V on LEDs, 138 Ohm resistor5 LEDs in series: 14.24V on LEDs, 195 Ohm resistorAny tips? Obviously you want to burn the most power on the LEDs and not on the resistors, but having too low of a resistance may put LEDs in a dangerous situation.Ivo
Sizing project boxes - Page 1
Forum section: electronics / projects

author: veedub565
author_rank: Frequent Contributor
timestamp: August 06, 2016, 05:19:34 pm
content: Hi, can anyone give me some pointers for sizing a project box ? never done it before.My PCB is 70mm x 140mm so I got a project box which was 80mm x 150mm thinking that would be fine. Unfortunately what the supplier doesn't say is that the screw holes for the lid are best part of 10mm thick each. So the PCB won't fit !

author: Zero999
author_rank: Super Contributor
timestamp: August 06, 2016, 08:20:36 pm
content: Look at the drawings to confirm there's enough space inside the enclosure for the PCB.You're quire lucky you have a choice. Most of the time I have to design the PCB to fit the enclosure. This can make laying it out more challenging, especially when I have to take account or the height of the components and some areas of the PCB can't have any components or tracks on the outer layers, as it will be mounted to a metal surface.

author: jeroen79
author_rank: Frequent Contributor
timestamp: August 06, 2016, 09:30:41 pm
content: What Hero999 said.Get drawings/datasheets/cad files for the enclosure and involve it early in your design.
Sizing up DC power supply for air compressor - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: February 07, 2018, 10:51:25 am
content: So I have this portable air compressor that I use to inflate my family's car tires on the car's battery power, however, I'd like to use it at home to dust off my computers and inflate some bicycle tires etc...The compressor is rated at 12V DC but I am not too sure on how much power I need.Using my 1500W power supply, I see that the inrush current at 13.8V is 51.3 A.Does that mean I need a 700W power supply to run this thing?Under no load, the compressor pulls 20A so that translated into 276W of power consumption.The current increases as the air pressure in the system rises and tops out 32A.My question is should I size my power supply for the 32A max or 51.3A of inrush current?I've measured these values on my fluke clamp meter.

author: cowana
author_rank: Frequent Contributor
timestamp: February 08, 2018, 01:26:55 pm
content: Most power supplies have a maximum peak rating (limited by the resistance/impedance of the components), and a maximum continual rating (limited by thermal dissipation).Therefore you need a power supply that can handle the 32A load continuously, with a peak power of >51.3A.

author: beanflying
author_rank: Super Contributor
timestamp: February 08, 2018, 01:44:19 pm
content: At start up DC loads like this draw HEAPS. In this case a small AGM 6-15Ah (UPS battery) and lowish (500mA) current charger will be a cheaper and smaller/lighter option. The AGM will give you more than you need for current at start up and plenty of time for a bit of dusting.

author: Damianos
author_rank: Frequent Contributor
timestamp: February 08, 2018, 05:05:14 pm
content: If the compressor is of the usual type that connects to the lighter plug, then the maximum current is hardly higher than ten to fifteen Amperes. Are available any data of it?

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: February 08, 2018, 06:22:34 pm
content: Quote from: Damianos on February 08, 2018, 05:05:14 pmThis is the one I'm talking about :http://store.arbusa.com/ARB-On-Board-High-Performance-12-Volt-Air-Compressor-CKMA12-P3572.aspxIt's meant to be mounted on the vehicle but I fitted it to a small toolbox so it can be portable instead.

author: james_s
author_rank: Super Contributor
timestamp: February 08, 2018, 06:30:55 pm
content: You can get 12V 50+ Amp hot swap server PSUs for little more than the cost of shipping on ebay. That's probably the cheapest power supply option you can find. I have several of them that I use for various things.

author: Damianos
author_rank: Frequent Contributor
timestamp: February 08, 2018, 09:28:31 pm
content: So, it needs a power supply with voltage between 12 and 15 V and current at around 40 A, that can withstand on over current about 150%.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: February 08, 2018, 09:30:54 pm
content: Got myself a meanwell 12 V 450 W power supply after testing it first and works like a charm!Thanks for the help
Sizing up my UPS cables - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: January 24, 2018, 08:21:20 am
content: I have a UPS with external batteries but I am not sure how thick I should go on the wiring of the batteries.It is rated at 700W 220V and pulls around 80A under full load.I did some voltage drop calculation and with my current 3 AWG wires of 1m, i get a voltage drop of around 0.1V under full load.Do you think this is reasonable? Will it decrease my runtime?I have access to 1/0 cable but they seem overkill for such low loads. Voltage drop would be about half as much but is it worth the extra $?

author: BradC
author_rank: Super Contributor
timestamp: January 24, 2018, 08:35:46 am
content: It entirely depends on how your ups measures battery voltage and calculates runtime.

author: cowana
author_rank: Frequent Contributor
timestamp: January 24, 2018, 09:57:59 am
content: Quote from: drummerdimitri on January 24, 2018, 08:21:20 am80A * 0.1V = 8W dissipated in cablesThat's roughly 1% of the total power draw - meaning that if you completely eliminated cable loss, your gain to runtime would be around that.Doesn't seem worth spending any more on thicker cables to me!

author: Siwastaja
author_rank: Super Contributor
timestamp: January 24, 2018, 10:59:35 am
content: Quote from: cowana on January 24, 2018, 09:57:59 amIn addition to this 1% loss, low-voltage cutoff happens 0.1V earlier than otherwise - as a crude approximation, this is about 5% difference in state-of-charge (i.e., assuming linear 100% = 13.0V, 0% = 11.0V), so expect about this much loss in the runtime.Also, according to the wikipedia table, 3AWG wire has ampacity rating of 85A at 40 degC temperature rise.So you are at minimum cable sizing right now, with some (approx 5%) loss in runtime, and cables that will run quite warm, but not dangerously so. It's OK, but I might consider going one or two notches up in size. "1/0" size is approaching overkill.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: January 24, 2018, 11:31:27 am
content: I can set my voltage cut-off and currently it's at 10 V even though the UPS shuts down when my my DMM value reached around 10.3 V or so.I and currently only used 400 W and pulling 45 A from the battery but though it would be better to size up for the maximum power capacity for future-proofing.In the manual, they say that 4 AWG is the minimum required thickness for the conductors. Knowing this and only having access to 3 AWG and 1/0 AWG, would the run-time from the cut-off voltage difference due to voltage drop make any significant difference in run-time? 5% is worth it if the cables run cooler.
SJ050NA-08A TFT? - Page 1
Forum section: electronics / projects

author: james_s
author_rank: Super Contributor
timestamp: August 21, 2017, 07:07:42 am
content: I noticed these little SJ050NA-08A VGA TFT displays are available quite cheaply from a number of sellers, supposedly made by Innolux I've had zero luck finding a datasheet. Has anyone used one of these? Even a pinout would be enough that I could work out the rest, they have a parallel RGB interface which I suspect is the typical hsync, vsync, dot clock, etc but without knowing the pinout or what they were intended to be used in I'm pretty much stuck.
SK-8120 switchmode (PWM) Datasheet required. - Page 1
Forum section: electronics / projects

author: peteb2
author_rank: Regular Contributor
timestamp: January 10, 2024, 06:26:34 pm
content: Has anyone a .pdf etc please for this? It's a Chinese manufactured switchmode/PWM powersupply 'management' IC please? It's a very common by the look device used in 100s of thousands of modules. I cannot find any data for it, block diagram, pinouts etc. Google provides images links to sellers, that's all. Anything appreciated!

author: coromonadalix
author_rank: Super Contributor
timestamp: January 10, 2024, 07:01:46 pm
content: with lots of googlingno datasheet, and many sites refer to TI as the maker ?? there is a dip package and another one who seems like an to-220 ?? confusing informations ?and some attached pictures found on a forum ?some say : SK-8120 and TL3844P are equivalenttake it with precaution, pinouts seems to differ / or their naming ??
SK6812 - 2020 orientation - Anyone use? - Page 1
Forum section: electronics / projects

author: zitt
author_rank: Regular Contributor
timestamp: February 05, 2022, 09:03:43 pm
content: What the heck is with these SK6812, 2020 packages. Talk about being the most assembly unfriendly package in the world.As far as I can tell; the package is square - so can't figure out orientation from that.There appears to be a small triangle point to on of the pads; but they are very small and on the bottom side of the package.There does not appear to be a top side mark at all.The "datasheet" provided by the aliexpress vendor doesn't provide enough detail to figure out what the triangle is indicating.https://www.aliexpress.com/item/32979408725.htmlIs it pin 1? Is it Pin 3?Does anyone know for sure? Have you built a project with this LEDs so have first hand knowledge?

author: zitt
author_rank: Regular Contributor
timestamp: February 06, 2022, 05:54:42 am
content: I figured it out and verified the pinout with a small Arduino program.Basically; the Triangle points to Pin 1 or VDD.I figured this out by using a 6x microscope and looking for the die in the package.The LEDs I received appear to be an equilvalent to:http://www.normandled.com/upload/202003/SK6812-EC20%20LED%20Datasheet.pdfwhich has the DIE in the top between pins 3 and 4.See top view pp 4.Now that I'm looking at this datasheet (and not the one the seller provides on their page) it clearly shows pin number on the "botoom" view which makes it easier. Using the botoom view in concert with the pin configuration makes it legible.Keep in mind; don't fall for the trap I did... I had used Sparkfun's LED library with a 2020 Neopixel footprint in my PCB design. These leds do not directly fit the sparkfun library. I think I can make it work by rotating the LED; but I'm going to have to be careful in triple verify.Finally; for those using FastLED.io's library; this LED seems to bet GRB or:FastLED.addLeds<SK6812, DATA_PIN, GRB>(leds, NUM_LEDS);
Ski goggle hud - Page 1
Forum section: electronics / projects

author: kelkel60
author_rank: Newbie
timestamp: August 18, 2016, 12:20:06 pm
content: Hey Guys,I'm thinking about building a HUD insert for a pair of ski goggles, similar to thishttp://hackaday.com/2013/04/05/snowboard-goggle-hud-displays-critical-data-while-falling-down-a-mountain/, but without using the glasses.It would consist of small micro-controller ( battery powered) connected up to an accelerometer and a very small (~10mm high) LCD display. The problem i'm having is finding a suitable display. Ideally it would be something like thishttp://www.syndiant.com/pdfs/SYL2061_ProductBrief.pdfThis chip has a 1024x600 resolution and is only 9mm X 24mm, but the company doesn't seem to supply to single users. Has anyone come across a place that sells a similar chip?The closest I've found is this:http://au.rs-online.com/web/p/oled-displays/8808584/but with a resolution of 96 x 16 i don't think it will work.

author: macboy
author_rank: Super Contributor
timestamp: August 18, 2016, 05:45:51 pm
content: OLED is a good idea. 96x16 is equivalent to 16 characters by 2 lines (with 7x5 pixel characters). I see plenty of 128x32 pixel OLEDs on ebay (or wherever) that would give you 21 char by 4 lines or fewer bigger characters (say 10 chars double size plus 2 lines of 21 chars, etc.).You don't need anything nearly as powerful (or power hungry) as a Raspi, instead you can use almost any cheap small microcontroller like a Arduino nano clone. It just needs to parse the serial data stream coming from the GPS module of our choice, and present that information in some meaningful way to the user on your display of choice. It's a relatively simple task. The 128x32 OLEDs are usually based on SSD1306 controller, supported by u8glib on Arduino which makes short work of writing information to the display.

author: kelkel60
author_rank: Newbie
timestamp: August 19, 2016, 02:51:06 am
content: The ebay OLEDs look pretty good, ill check them out. For a micro-controller I was thinking of using a teensyhttps://www.pjrc.com/teensy/which I can program with arduino, would it be best to use an accelerometer or a gps for getting the speed?

author: plazma
author_rank: Frequent Contributor
timestamp: August 19, 2016, 05:45:27 am
content: Look into FLCOS display modules. They have single pixels showing all colors so they look good even when magnified. With an OLED you would see individual subpixels when magnified or looking close.

author: Marco
author_rank: Super Contributor
timestamp: August 19, 2016, 06:33:53 am
content: Maybe you could hack an Epson Moverio? A normal display sitting at a focus distance of a couple of cm won't be very useful for a lot of people.PS. or a google glass of course.

author: Kilrah
author_rank: Unknown
timestamp: August 19, 2016, 08:03:57 am
content: The hardest is usually not the display but the optics.
Skinny LED standoffs - Page 1
Forum section: electronics / projects

author: ajb
author_rank: Super Contributor
timestamp: September 01, 2015, 04:25:06 pm
content: I'm trying to tuck some LEDs between vertical pots on a PCB. 3mm LEDs fit nicely between the bodies of the pots, but I need to space the LEDs about 8mm off of the board to match the panel height, which means some sort of spacer. Trouble is, all of the spacers I'm seeing, even those nominally for 3mm LEDs, are ~5mm diameter, which won't fit between the pots. I know I've seen much skinnier spacers on 3mm LEDs, but of course can't seem to find them now, when I need them.I could go up to 4mm diameter, but closer to 3mm would be better, and 8-8.5mm would be ideal on the length. I could also do an SMD LED and a vertical light pipe instead, but again the base would need to be max 4mm wide, and most of what I'm finding are ~5mm, and I'd need it to be ~12.7mm tall. Anyone have any suggestions?

author: codeboy2k
author_rank: Super Contributor
timestamp: September 02, 2015, 01:01:05 am
content: Is this for production or one-offs?If one-off and you don't need too many, you can use the plastic case of standard 0.1" pitch female header pins. These are also 0.1" square, and 0.325" tall.This works out to 2.5mm x 2.5mm x 8.2mm tall. Pull out the socket part and you have a nice square spacer for the LED leads.Or leave them in, since 3mm leds have 0.1" lead spacing, you can use them as sockets

author: ajb
author_rank: Super Contributor
timestamp: September 02, 2015, 02:41:59 am
content: This is for production. Not crazy volumes, but enough that I'd rather not have to bodge it. The header sockets aren't a bad idea though. There are some panel mount light pipes that would work, but the finished product is already going to have two other PCBs mounted to the same panel, one of which has a 3mm LED mounted on a standoff, and the other which has right angle light pipes, so I'd prefer to avoid adding a third style of indicator if I can avoid it, if only to satisfy my inner perfectionist. I could swear I've seen some standoffs that are basically an "H" shape with rounded sides that fit between the legs of the LED.Thanks.

author: fivefish
author_rank: Frequent Contributor
timestamp: September 02, 2015, 03:53:28 am
content: Can you just use wire insulators cut to right length, and insert them into each LED leg?

author: Unknown
author_rank: Unknown
timestamp: September 02, 2015, 04:52:03 am
content: Bivar ELM 7-8MM? Mouser shows 900+ in stock.

author: ajb
author_rank: Super Contributor
timestamp: September 02, 2015, 02:28:04 pm
content: Quote from: Tac Eht Xilef on September 02, 2015, 04:52:03 amPerfect! I even looked at Bivar's catalog, or maybe I was looking for lightpipes at that point. . . anyway, thanks very much!
Skori Mini Tesla Coil questions - Page 1
Forum section: electronics / projects

author: Jwillis
author_rank: Super Contributor
timestamp: May 19, 2018, 03:26:30 am
content: New project and a few questions concerning the oscillation frequencies.Here's the website for this projecthttps://translate.google.ca/translate?hl=en&sl=hu&u=http://skory.gylcomp.hu/tesla/mini_tesla.html&prev=search.I used google translate since I can't read Hungarian.I did my best to translate the most important descriptions the circuit diagram.Ok The frequency at the 555 is only around 70 Hz. Which seems low for driving T1 and T2 Mosfets .They get pretty hot even with heat sinks .Of course more heat sinking will be required later but for short tests what I have should do for now.The transformer is a 2:1 but only 11/22 winding's not the prescribed 15/30 .My coil is different from the original.And the circuit only pulls around 2.5 amps at 13.8 volts.I'm running the PSU in Parallel for 10 amps .Now I figure my primary coil should run around 78 kHz not 70 Hz that would put the secondary coil I have at around 505 kHz and the C4 ,L4 oscillator from the example is 400 kHz .These are estimatesShould I kick the 555 to 78kHz and the C4,L4 oscillator to 505 kHz.Or am I looking at this wrong .The circuit works sort of but not as good as what it could be .Pardon the mess and lighting .I'm still in the process of wiring my lab .And don't make fun of my toroid .Took me all day to make that .I'll make a better one later.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: May 19, 2018, 04:24:00 am
content: I think the way this is supposed to work is that the 555 produces a square-ish pulse train to the primary that starts the secondary ringing. Once it rings, the feedback circuit takes over and should drive the primary at the secondary's resonant frequency. So the actual frequency of the 555 is rather unrelated, you are just using the edges of a low-frequency pulse to start the ringing process. I think. The way the schematic is laid out makes it a little difficult to interpret.It seems that this also works as an "interruptor" so that the coil will be working in staccato mode.So I'd stick with the specified component values unless someone else has a better idea about how the circuit works.You might try "phasing" the primary coil: that is, reverse its connections and see if that makes any difference in the performance and current draw. Ditto with _one_ winding of the toroidal transformer. SO that's 4 different phase configurations to try.But seriously... lose the breadboard and put this circuit together either with the PCB or by using another prototype method involving soldered connections and perhaps a ground plane.
Sky STB IO-Link pinout - Page 1
Forum section: electronics / projects

author: johnkenyon
author_rank: Regular Contributor
timestamp: May 21, 2020, 08:49:28 am
content: I'm looking for a cheap composite to UHF video RF modulator, which can turn a PAL composite video signal into a UK analogue UHF PAL-I signal (sound carrier on 6MHz).Ebay shows cheap beyond £7-£8 chinese modulators which output at 61.25MHz (aka VHF Channel 3, which in turn indicates NTSC)The best cheap option seems to be a Sky IO-Link box, which has a 10 pin mini-DIN connector which plugs into a Sky set top box.The down side is that the IO-Link pinout seems to be either the most closely guarded secret on the internet, or the most ungooglable subject ever.All searches for "io-link" seem to take you consumer targetted "howtos" or sales info, or an unrelated IEC standard for talking to sensors and actuators.Does anyone know which pins on this connector present power, audio and composite video to the modulator?(or even better has anyone got a full pinout for the connector?)(Edited: subject changed and the text below added -When you read your post a few hours later and realise that 90% of the readership don't know what "Sky IO-link" is...)The IO-link is a socket on the back of more recent set top satellite TV receiver boxes (STB) issued by Sky TV (at least in the UK, possibly elsewhere where they have the same presence).This allows the set top box to be shipped without the following hardware:* One or more RF outputs* A "magic-eye" receiver, which takes a remote control signal fed back up the co-ax from a remote TV which allows you to control the STB from another roomIf you need this functionality, then you buy an IO-Link "box" which has a single cable which plugs into a 10 pin mini-DIN socket.
SLA Discharge? - Page 1
Forum section: electronics / projects

author: Well, That Was Unexpected
author_rank: Newbie
timestamp: April 17, 2015, 03:34:07 pm
content: Apologies for the post length, this is all based on my electrical understanding. Please correct where need be, any advice greatly appreciated.In reference to a typical SLA datasheet - I.e:http://www.master-instruments.com.au/cgi/ajax/get_file/59669/1The Problem:I'm trying to ascertain a \ the best way to determine how discharged an SLA battery is. In turn, allowing me to ensure the Depth of Discharge is kept under control increasing the life span of the battery.Obviously the datasheet is helpful and used when designing a product where there are some design parameters about how long you want the battery lifespan to be and how long you want it to last before charging. However, I use SLA's for camping to power a whole host of electronics as required so my load varies and I can sometimes be required to go days without a charge. Hence, a battery meter would be great. Most meters I've seen use just the voltage which I don't like (more on this in a tick.)The front runner for a pre designed pre made solution at the moment is this little guy:http://ki0bk.no-ip.com/~pwrgate/LLPG/Site/SLA_Batt_Mon.htmlHowever, I don't like it because I'd like a bit more info, you can't change the low voltage point (though I'm sure this could be hacked) and, its a microcontroller solution. In regards to the last part I'd like to head down the more discrete path. Reason being that I want this thing to be rugged and able to handle going camping, hiking, accidentally getting too warm, a bit crushed etc.The limitation and difficulties with designing such a device are that:The discharge characteristic curve is pretty flat. The area under the curve (i.e. integrating the function of that curve) yields the Depth of Discharge. If one were to colour in half of the area under that curve at say the 50% mark then the change in voltage would be relatively minor.the capacity of the battery is unknown. That is the extent it has reduced from its initial notional capacity due to age, storage conditions, nature of discharges etc etc mean that putting a figure on this is pretty much impossible to me?If I were to use a micro controller I imagine it would be possible to continually measure the load I'm drawing and have it keep track of this over time. Inferring the amount of energy used and then giving a rough depth of discharge \ battery meter. I would just have to allow for a healthy margin of reduced battery capacity. But again its using a micro!On a side note, this may later form part of a larger project that basically is an all in one camping power unit for my longer camping with a car trips- Multiple batteries, multiple solar inputs, inverter outputs, DC to DC converter power outputs for charging laptops etc. etc. Effectively knowing when a battery is fully charged (comparatively easy) and discharged forms a big part of this. In this situation a micro would be required so if that's pretty much the best way then so be it.So any advice as to what other people have done?
SLA powered cell phone charger - Page 1
Forum section: electronics / projects

author: edy
author_rank: Super Contributor
timestamp: August 25, 2014, 11:38:13 pm
content: Hi folks,I have some basic questions about charging a cell phone using an SLA 12v battery from a UPS or alarm system. Can a regular cigarette lighter plug adapter meant for your phone be the only thing needed? Just hook up to the a battery and assume it is safe? How do I go about converting the Ah capacity given conversion from 12v to 5v in the adapter and other efficiency issues? Is there a better more efficient method using a voltage converter and do I have to worry about the phone or converter drawing too much current? Any help or pointing in the right direction will be appreciated. Thanks.

author: DanielS
author_rank: Frequent Contributor
timestamp: August 26, 2014, 02:26:07 am
content: A 12V SLA battery is almost exactly the same thing as a car battery except for the gellified or AGM electrolyte. Charging using a 5V USB power adapter is going to be as safe as the adapter's design is and this is true regardless of what the power source might be.BTW, "USB chargers" are nothing more than whatever-to-5V power supplies. The electronics that actually control charging over USB are contained in the USB device being charged.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 26, 2014, 04:45:56 am
content: You'll probably want some sort of low voltage indicator in order to avoid cycling the battery too much.
slayer exciter barely works, my first high voltage and diy coil project - Page 1
Forum section: electronics / projects

author: mookie1590
author_rank: Contributor
timestamp: November 23, 2021, 05:22:35 pm
content: Just trying to better understand this. I'm getting very poor sparks from my secondary, so small you need the light off and to be looking for it.I do know its oscillating, I'm getting a sine wave on the base of my TIP41 transistors, I was using TIP31, but the primary coil killed them.How it did, is my question. I put my oscilloscope probe on the collector of the circuit. And The voltage here is 100volts. Is there supposed to be high voltage on the primary like this, I'll post a pic from my scope. I never measured the output of the secondary, it could kill my scope.The Led that is connected to the base to ground does light up.Also the coil I made by hand is a single layer going all the way up a paper towel tube. Should I instead of doing one layer at 300 turns, do 3 layers at 100 turns that would equal a total of 300 turns.My primary is about 3 turns.also, I found that pulling out the base resistor that turns on the transistor at the start up doesn't affect the circuit. It still runs, until I touch the secondary, then it shuts down and I have to put the resistor back in to get it to work. I thought the secondary coil was supposed to pull the transistor down to turn it off, but it still runs without the resistor. unless touched. But it does work and oscillates. I'm confused as to why it can still run without the resistor. Unless of course I've made a mistake. Or I'm misunderstanding what each variable is supposed to do.The photo labeled 10.jpg is the scope across the primary coil. ground clip to one side, probe to the other. My oscilloscope used a 5volt wall wort so I'm assuming it isnt ground referenced like other scopes. the second photo is negative rail to the collector of the transistor, says pic 9.jpgI can get a photo of my coil setup later if need be. Thanks for any help with this.
Slayer Exciter works perfectly on breadboard, but not so well on perfboard - Page 1
Forum section: electronics / projects

author: nshin31302
author_rank: Contributor
timestamp: July 09, 2015, 06:12:20 pm
content: So I built a slayer exciter tesla coil using this tutorialI made the secondary using some PVC and some magnet wire and bread boarded the circuit described in the video with the same component values except for using a TIP3055 instead of a MJE3055T. So the slayer exciter circuit worked perfectly on breadboard brightly lighting a CFL and drawing inch long arcs. So I decided to make the circuit more permanent by soldering it to a pad per hole style perfboard from RadioShack. After I was done, I tested it. The circuit on perfboard brightly lit a CFL and drew an inch long spark, but only for a few seconds. The arc length grew smaller and the CFL's brightness gradually diminished. I tried switching the primary coil's leads around, but I got the same result. What's wrong with the circuit?

author: mmagin
author_rank: Frequent Contributor
timestamp: July 10, 2015, 03:05:42 am
content: I'm guessing you've encountered a situation where the stray capacitance between the breadboard rows affects the circuit. As a test of this theory, looking at the pinout of the TIP3055, I would try adding (to your soldered prototype) about 3-5 pf between base and collector and collector and emitter and see what happens. If you don't have tiny capacitors like that, try making "gimmick capacitors" out of twisted pairs of wire maybe an inch or two long (insulated where they're touching).

author: Circlotron
author_rank: Super Contributor
timestamp: July 10, 2015, 03:30:30 am
content: 3055 is a hopeless transistor for high voltage, high frequency switching. If you must stick with a bipolar, perhaps try something that was intended for TV horizontal deflection.

author: ale500
author_rank: Frequent Contributor
timestamp: July 11, 2015, 05:30:18 am
content: The original 2N3055 by Motorola had a transition frequency of 15 kHz. Maybe ti's TIP3055 is a bit different, anyways who did manufacture yours ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 11, 2015, 06:29:28 am
content: 3055 is best left to the history books. Consider the datasheet spec: it's all about minimums. So you could get some slick-shit audio amp transistor with fT in the 10s of MHz, or some almost-germanium POS that's slow as molasses.I suspect most are fallout from MJ15xxx production, or something like that: there's simply no fabs that old still around, making truly old shit. So whatever generic power transistor die doesn't meet spec for a higher valued product, is binned into the 3055's instead.I'd much rather buy the properly spec'd part in the first place...But anyway, there are better circuits to use for the present application, anyway, even among the overly simple (and dangerously fickle) types.Tim