hybridfree/eevblog-posts huggingface dataset:
Small, Cheap AC Panel meters - Review and teardown - Page 1
Forum section: electronics / projects

author: intabits
author_rank: Frequent Contributor
timestamp: December 07, 2019, 11:55:04 am
content: I did a quick and dirty review and teardown of these cheap digital AC panel meters that read voltage and current.I got a blue one and a green one:-The insides (I can't see any markings on the main chip):-Pros:-Bright clear displayCheap (abut US$3.60)Easy to mountCan sense up to 100A (and up to 500V)Cons:-Doesn't show currents less than about 750mACurrent readings seem to be be low/inaccurateVoltage readings are also a little hit and miss, only accurate to within about 2-3%.For low currents they are probably pretty useless, but if the load is always over 1 amp, they may have a place.I'm thinking that it may be possible to add a trimpot to calibrate the current measurement. (But I need to get something to accurately compare it against)Video:-

author: magic
author_rank: Super Contributor
timestamp: December 07, 2019, 03:10:55 pm
content: Is this for mains?How much overvoltage before

author: intabits
author_rank: Frequent Contributor
timestamp: December 07, 2019, 08:08:34 pm
content: Yes, it is for mains.The box says: 50V to 500V, and 0-100A(meter seems to need a minimum of about 20V to operate)

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 07, 2019, 08:44:56 pm
content: How is the current sensing achieved?

author: intabits
author_rank: Frequent Contributor
timestamp: December 07, 2019, 09:06:47 pm
content: The unit comes with a current transformer, that connects via a 2 pin inline connector to a flying lead coming out of the back of the device.The mains is connected via 2 screw terminals on the body of the unit.I should have included a pic showing all this:-
Small desktop AM transmitter (keri) - Page 1
Forum section: electronics / projects

author: Gip-Gip
author_rank: Contributor
timestamp: December 16, 2017, 03:22:01 am
content: Just for fun and educational value I've started work on a small transmitter named after the Greek word for candle; keri!It's primary goal is to provide a signal to the few AM radios I have around the house, and the secondary goal is to look good doing it! I plan to have the transmitter set up like a mini model antenna on a wooden base, which I think would be kinda neat.I made a custom pure-sine-producing transmitter circuit and I would like to know how everyone thinks of it. I'm really new to designing circuits, let alone RF transmitters, but so is everyone who posts an AM Transmitter Tutorial bc the schematics are pretty ugly IMO.However, if it turns out my design is utter trash I'll give in to the crappy online schematicsSchematic In attachments

author: Gip-Gip
author_rank: Contributor
timestamp: December 18, 2017, 06:10:45 pm
content: I finished laying out the pcb just a few minutes ago and I must say it turned out to not be as ugly as I thought it was going to beOf course, that's from my perspective, and I'd really appreciate it if a professional is willing to give their opinion.I ran the PCB through OSHPark because it looks far less ugly than a KiCad screenshot, but if someone really wants to go through the torture, I will provide...
Small DPDT On-On rocker with snap-on panel mount? - Page 1
Forum section: electronics / projects

author: analogo
author_rank: Regular Contributor
timestamp: April 19, 2018, 11:31:45 pm
content: I need a DPDT On-On (or On-Off-On) rocker in a panel.All the rocker switches that I have found are quite big: about 25 mm in width. Is there something smaller around?I am looking for name brand switches and I need to switch low voltages (< 24 V) and low currents (< 1 A). The switches are to be mounted with a snap-on mechanism onto the panels. All I have found are big chunky switches with six 6.3 mm fast on connectors. I understand that they need to be so big to reliably switch 10 A @ 240 V AC, but I don't need that.DPST and DPDT On-Off switches can be found in the more compact 15 mm width version. Aren't there similar switches for DPDT?

author: westfw
author_rank: Super Contributor
timestamp: April 20, 2018, 05:34:37 am
content: Digikey's parametric search lets you specify size and mount style. They have about 40 in-stock snap-in dpdt rocker switches with widths of about 1/2 inch (13mm)(I don't know whether this will include the search criteria)...https://www.digikey.com/products/en/switches/rocker-switches/195?k=switch&k=&pkeyword=switch&FV=11400e1%2C2080004%2Cc3c0066%2Cc3c0069%2Cc3c006a%2Cc3c006b%2Cc3c006c%2Cc3c007a%2Cc3c04cc%2Cc3c00b3%2Cc3c00b4%2Cc3c00f2%2Cc3c00f8%2Cc3c0101%2Cc3c015f%2Cc3c0039%2Cc3c0272%2Cc3c0287%2Cffe000c3&quantity=1&ColumnSort=0&page=1&stock=1&pageSize=25QuoteI don't understand what the difference is between an on-off and an on-on dpdt switch... Are you sure you're not getting hung up on (inaccurate) labels?

author: analogo
author_rank: Regular Contributor
timestamp: April 20, 2018, 07:23:31 am
content: Quote from: westfw on April 20, 2018, 05:34:37 amThanks, Mouser showed none. Narrowing down the search to On-On/On-Off-On switches gives about 10 results. And quite expensive. But that will do.Quote from: westfw on April 20, 2018, 05:34:37 amDPDT On-Off are switches where one position is not broken out to terminals, so they have only 4 terminals and they are more compact. Basically DPST, but many manufacturers and Mouser call them like DPDT On-Off (especially on push buttons):https://eu.mouser.com/Electromechanical/Switches/_/N-5g2h?P=1z0z2xkZ1z0z24z&Ns=Pricing%7c0
Small Dynamic Mic Inserts - Page 1
Forum section: electronics / projects

author: Mike Warren
author_rank: Unknown
timestamp: August 27, 2015, 10:04:53 pm
content: I'm not having much luck finding a source of dynamic mic inserts for use in a custom headset we make. Currently, we use readily available and cheap condenser inserts that everyone sells for <$1, but these need to be powered, which limits the situations they can be used in.I need them to be reasonably compact, and with the diaphragm protected.Of course, price, as always, is a factor.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 28, 2015, 03:59:57 am
content: That's going to be difficult since the built in preamp is exactly what makes it possible to get good sensitivity in a small size. Unpowered microphone inputs are also pretty rare nowadays.

author: mikerj
author_rank: Super Contributor
timestamp: August 28, 2015, 10:20:22 am
content: Maybe you could design an in-line adapter that contains a small coin cell, resistor and coupling cap for use with unpowered microphone sockets? A dynamic mic cartridge is going to be significantly larger than an electret mic insert, and the output voltage is probably going to be lower.
Small ferrite transformers for offline 1W flyback converter - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: June 26, 2018, 03:06:12 pm
content: Does anyone have data for type EE cores, or type EP cores for small offline (1-2W) flyback transformers. Neither ferroxcube or TDK list any data for these.We also need the data on the former dimensions.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: June 27, 2018, 09:16:50 am
content: Quote from: treez on June 26, 2018, 03:06:12 pmSorry, whut?https://product.tdk.com/info/en/products/ferrite/catalog.html#1432825602695https://www.ferroxcube.com/en-global/products_ferroxcube/detail/shape_cores_accessories/ep_and_epx_cores
Small footprint script language; yalex - Page 1
Forum section: electronics / projects

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: March 11, 2019, 01:23:59 pm
content: Hi everyoneI've been playing around with a small scripting language for my electronics projects.Not every projects needs a scripting interface (some would rightfully argue no projects needs it) but I like having the ability to force states, read debug statuses etc.https://github.com/AlexanderBrevig/yalexI've used it on ATmega328, CC1310, nRF52 and STM32F1 and F4.Arduino sketch, typical embedded config.The syntax is based on reverse polish notation, and will probably seem very strange if you've never seen that before. Here is an implementation of Fibonacci:Code::fibstep (R1R R2R + R3S pop R2R R1S pop R3R R2S pop R4R 1 + R4S pop rec):rec (R4R R0R 1 + < 'fibstep _ select):start (R0R 1 - R0S pop rec pop pop pop pop pop pop R3R):fib (R0S 0 R1S 1 R2S 0 R3S 1 R4S R0R 3 < 1 'start select)10 fib55There's a side by side explanation with C of that on the github.Just wanted to make a post about it as I find it useful, and maybe one of you will too.I am totally OK with those of you who thinks this is a total waste of time. I do not wholeheartedly disagree.

author: dmills
author_rank: Super Contributor
timestamp: March 11, 2019, 01:48:27 pm
content: It's pretty much Forth!Regards, Dan.
Small form factor LCD / E-Ink Display - Page 1
Forum section: electronics / projects

author: docmur
author_rank: Regular Contributor
timestamp: June 25, 2015, 06:07:41 pm
content: Hey GuysI'm looking for a 1.44 Inch OLED / E-Ink display for use on an embedded project, anyone know of any good modules?

author: Throy
author_rank: Regular Contributor
timestamp: June 26, 2015, 06:37:39 am
content: Have you taken a look at Newhaven? They have some small form OLED displays. Not sure if you need exactly 1.44" or if you have a little room to play with. They have displays from 1.27" to 1.69".http://www.newhavendisplay.com/oled-color-oleds-c-119_626.html

author: Marco
author_rank: Super Contributor
timestamp: June 26, 2015, 07:13:51 am
content: If you can compromise on the size maybe Sharp memory LCD's would be an alternative to e-ink? (As used by Pebble watch for instance.)

author: jdraughn
author_rank: Regular Contributor
timestamp: June 26, 2015, 10:14:11 am
content: http://www.wisechip.com.tw/style/frame/templates15/product.asp?lang=2&customer_id=2641&name_id=128417&content_set=color_1&Directory_ID=70278

author: MarkF
author_rank: Super Contributor
timestamp: June 26, 2015, 10:26:47 am
content: Adafruit has the same 128x96 and 128x128 OLED breakout boards as Newhaven. They are more expensive because they have 3.3VDC regulator on board and level shifters for the signals when you're using 5VDC devices. I have the 128x96 version and like it very much.OLED Breakout Board - 16-bit Color 1.27" w/microSD

author: Warhawk
author_rank: Frequent Contributor
timestamp: June 26, 2015, 10:46:05 am
content: Few weeks ago I saw a post here on the forum telling that these OLED displays have a limited lifetime and should not be operated in aconstant-onoperation.Since you mentioned eINK, I guess it might be your case.

author: MarkF
author_rank: Super Contributor
timestamp: June 26, 2015, 12:08:16 pm
content: Quote from: Warhawk on June 26, 2015, 10:46:05 amFrom the datasheet of these OLED displays (Life time defined as 50% of its initial brightness):Life Time (90 cd/m2) is 10,000 hrsLife Time (70 cd/m2) is 13,500 hrsLife Time (50 cd/m2) is 20,000 hrsI changed the configuration settings of my unit to significantly reduced the brightness from that provided in the Adafruit library and the defaults provided in the datasheet. These displays are extremely bright.
Small H-bridge? - Page 1
Forum section: electronics / projects

author: piranha32
author_rank: Unknown
timestamp: October 08, 2021, 06:33:41 am
content: Hi,A set of cheap string LED lights died after an hour of use (the dropper resistor desoldered itself), and I would like to use the LEDs for another project. Unfortunately, driving them requires AC current: all LEDs are connected in parallel, but odd-numbered diodes are connected one way, and even-numbered - in reverse.The original driver uses what looks like an H-bridge in an SOT-6 package, connected directly to a microcontroller. It has markings 116/048 (see attached pic), but googling and searching stores (Digikey, Mouser, etc) I could not find anything even remotely similar to this IC.Does anyone recognize this device, or has ideas what can be used in place of it? It doesn't need to be an exact replacement, a small SMD H-bridge which can be driven from an uC is fine.

author: langwadt
author_rank: Super Contributor
timestamp: October 08, 2021, 07:55:09 am
content: https://www.holtek.com/productdetail/-/vg/HT7K1201?

author: piranha32
author_rank: Unknown
timestamp: October 08, 2021, 08:00:23 am
content: Looks like that's it. Thanks!
Small heating disk for project - Page 1
Forum section: electronics / projects

author: Muggs
author_rank: Newbie
timestamp: February 21, 2022, 03:05:33 pm
content: Hello All,I'm looking for a small heating disk for a project that I'm quoting. Ideally I would want a 1/4" disk heated by 12Vdc and ranging in temp from ~30C to ~50C (86F to 122F).Does anyone know of a source for something like that? I can find plenty of "gum-stick" sized ones but nothing like a disk that is that small.TIA,Muggs

author: reboots
author_rank: Regular Contributor
timestamp: February 21, 2022, 08:02:19 pm
content: Perhaps you can simply use a resistor in a favorable package. Johnson Dielectrics RWPB03W350R0TS is a 350-ohm wirewound resistor in a 0.320x0.300x0.102" axial package, which is a little larger than your 1/4" requirement. 350 ohms with a 68-ohm series resistance at 12V would dissipate 288mW through the package, approaching its power rating of 0.3W. Whether that's hot enough will depend on the rest of your project, and of course the temperature isn't regulated; you would need either closed-loop control or a predictable thermal gradient.https://www.mouser.com/ProductDetail/Johanson-Dielectrics/RWPB03U100R0TS?qs=sGAEpiMZZMug%252BNZZT2EIM%252Bw093hgTVdcWe%252BgpNzjgG8%3DThat part is an expensive precision resistor, and Mouser shows only qty/4 in stock today. If you think you might need production quantities, and/or are ready to devise a mounting method, there are cheaper and more available wirewound SMT resistors, with higher power ratings, in smaller packages.

author: coppercone2
author_rank: Super Contributor
timestamp: February 21, 2022, 10:08:05 pm
content: that would be best suited on a aluminum substrate PCB IMO with some heat transfer glue poured on top the resistors (the ones they use for flashlight LED). Chassis mount resistors would be better or ones with a thermal pad.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 21, 2022, 11:10:51 pm
content: How about a steel washer and a simple induction heater circuit?

author: Muggs
author_rank: Newbie
timestamp: February 24, 2022, 03:57:48 pm
content: Thank you all, I really appreciate your insights.
Small IC to allow from 24v to 5v and vice versa - Page 1
Forum section: electronics / projects

author: Yaroooo
author_rank: Regular Contributor
timestamp: July 08, 2019, 01:18:50 pm
content: I'm looking for a suggestion of an IC. On my board I've very lack of space and I'd like to place 2 small IC that allow me to translate from 24v to 5v and another to 24v to 5v. Signal is a PWM of 200kHz, current sink max. 50mA. Looked for an opto but found only slow devices. Product suggestion? Thanks!

author: Zero999
author_rank: Super Contributor
timestamp: July 08, 2019, 03:33:11 pm
content: Just use a MOSFET driver, such as the TC4432.http://ww1.microchip.com/downloads/en/devicedoc/21424c.pdf
Small LCD TFT (3.3v) datasheet says backlights need ~18v. Is that right? - Page 1
Forum section: electronics / projects

author: carl0s
author_rank: Unknown
timestamp: May 11, 2018, 07:34:35 pm
content: As per title.. am I missing something fundamental, or is some sort of converter needed?Edit: I suppose I have to use one of these?https://www.reichelt.com/gb/en/?LANGUAGE=EN&CTYPE=0&MWSTFREE=0&CCOUNTRY=447&ARTICLE=189129&PROVID=2788&wt_guka=54951035955_263550070685&PROVID=2788&gclid=CjwKCAjw_tTXBRBsEiwArqXyMuXcMZ3ugoxhY3f3vWfiPoJm7Fvcn-RJvhv1UWNqbgg-qXsvlXKzdxoC4c8QAvD_BwEI'm sort of surprised. I thought 3.3 to 5v would be enough for a dial/clock sized round LCDThe LCD TFTs in question are these (datasheets):http://www.internetsomething.com/lcd/3.3-NMLCD-T334TOS-01.pdfhttp://www.internetsomething.com/lcd/DT034XVZ01.pdf

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: May 11, 2018, 08:14:14 pm
content: The LEDs will be in series with about 2.8 forward voltage each. So 18 volts if the forward current is 20mA as shown in table 6.2.You need a constant current driver.

author: carl0s
author_rank: Unknown
timestamp: May 11, 2018, 08:37:19 pm
content: ST suggest the stld40dpur in some of their datasheets / examples, but I was hoping to for something that's not QFN.

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: May 11, 2018, 08:49:52 pm
content: Some of these are more friendly...https://www.digikey.com.au/products/en/integrated-circuits-ics/pmic-led-drivers/745?keywords=&sort=&pv87=2&pv48=25

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2018, 08:51:34 pm
content: LT3465 still around? TPS61160? MIC2289?Tim

author: carl0s
author_rank: Unknown
timestamp: May 11, 2018, 09:05:26 pm
content: This thing looks OK?https://www.diodes.com/assets/Datasheets/AP5724.pdf

author: carl0s
author_rank: Unknown
timestamp: May 11, 2018, 09:18:39 pm
content: Quote from: carl0s on May 11, 2018, 09:05:26 pmThink i'm going to go with that. The datasheet is pretty friendly, and the price is good.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2018, 09:18:48 pm
content: Looks fine.Tim

author: carl0s
author_rank: Unknown
timestamp: May 11, 2018, 09:21:01 pm
content: Quote from: T3sl4co1l on May 11, 2018, 09:18:48 pmIt says "EN Pin Pull Low Current - 4 - 6 μA" which sounds good. So my MCU can PWM the EN pin rather than needing to put a transistor in between it and the MCU pin or whatever.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2018, 11:48:52 pm
content: Yes. The other way is to PWM fairly fast, so that the controller or output filter smooths out the PWM. I think some do this internally, even. The practical difference is continuous dimming versus flickering on-and-off operation.Tim
Small LED dot matrix display - Page 1
Forum section: electronics / projects

author: davorin
author_rank: Unknown
timestamp: June 29, 2018, 08:32:16 am
content: Good morning (o;For a new design we would need a tiny display around 20mm x 15mm max to show water temperature, flow and so on...Does anyone know of a small LED dot matrix display/module similar to the retro LTP-305 display?Problem with most dot matrix LEDs are that they have a border around the matrix so you can't extend the matrix to be used as a 20x7 for example...

author: Rolo
author_rank: Regular Contributor
timestamp: June 29, 2018, 09:13:08 am
content: Like these? 18*13mm green.

author: davorin
author_rank: Unknown
timestamp: June 29, 2018, 09:18:13 am
content: HelloUnfortunately they are to big for our design...the borderless matrix would be perfect though (o;4 digits should take up a width of 20mm...so each matrix should be around 5mm in width..The KPG-0603 SMT LED might be another option to do an own matrix with those 0201 package LEDs....

author: a59d1
author_rank: Regular Contributor
timestamp: June 29, 2018, 09:21:50 am
content: Have you considered using an OLED?

author: davorin
author_rank: Unknown
timestamp: June 29, 2018, 09:39:24 am
content: Yes of course.....though they have mostly a large border at one side for the flat cable...Also a problem might be the fact that the display might not be visible enough through a dark translucent plastic...But some OLED samples should arrive today for visibility testing...Hmm...those 0201 SMT LEDs are nothing for self soldering at my age (o;
Small LTC6655 Voltage Reference board - Page 1
Forum section: electronics / projects

author: Wirehead
author_rank: Regular Contributor
timestamp: November 11, 2015, 12:19:59 pm
content: Hi All,I've made a small board for an LTC6655 ref (any voltage you want) and it works pretty good. I've taken into account most of the datasheet recommendations in regards to grounding, ground planes, sense wire, decoupling, output cap selection.In regards to that output cap (I've used a 10uF metalized polyester cap), here's what the datasheet says:ESR less than 0.1 Ohm @ 100kHzNo X7R due to piezoelectric effectFor very low noise, film caps should be usedBetween 2.7uF and 100uFSome other items related this reference from the datasheet:Stiffer PCB's are preferred (Oshpark is pretty good)Mount it near the edge of the board (not perfect in my case, but it's a really small board)Pin4 is the actual ground, star grounding preferredPower and ground planes should be omitted under the voltage reference (also reduces thermocouple effects)For all those that would like to give it a go, I've included the gerbers, they work out fine for OSHPark and the likes.I'm in the progress of buying some calibrated Bench DMM's; so for now, you'll have to do with a shot of a VC99 (I can hear people screaming already; but hey, It's bang on)

author: branadic
author_rank: Super Contributor
timestamp: November 11, 2015, 06:50:37 pm
content: You better have used LTC6655-LS8 instead of MSOP package.

author: Wirehead
author_rank: Regular Contributor
timestamp: November 11, 2015, 07:20:06 pm
content: Yes, the LS8 package is better; but you need to reflow it, this package can still be soldered "the old way". I can make a PCB / gerber for the LS8 package if you want to? I'll add in the slots as well

author: branadic
author_rank: Super Contributor
timestamp: November 11, 2015, 08:56:39 pm
content: With some experience soldering of the LS8 package by hand is no problem whatsoever.Anyway, I don't need a reference board and if I would design it in a different way.
Small pin receptacles - Page 1
Forum section: electronics / projects

author: Strand17
author_rank: Contributor
timestamp: September 14, 2017, 03:52:21 pm
content: Hello,I am looking for small pin receptacles and would be very thankful for hints where to find a suitable type.Background - At work I am using hot wire anemometry to measure the velocity of air in a wind tunnel, for instance in the boundary layer of an airfoil. Our hot wire probes (see picture) fits into a tube-shaped holder. In the bottom of the tube is a connector mating with the two pins at the rear of the probe (the pins on right side in the picture). The connectors in the current probe holders are rather simple and not as reliable as we would like them to be.So, I am looking for alternatives. The key parts are the pin receptacles for the connector. The dimensions of the pins at the rear end of the probes are:Pin diameter: 0.45 mmExposed pin length: 2.3 mmPin centre distance (pitch): 0.85 mmThe whole two-pin connector fits in a tube with 2 mm inside diameter.I have checked at Mill-Max but they do not seem to have a receptacle which fits the pin diameter and in the same time has small enough an outside diameter for the required pitch.Any suggestions?Jonas
small potentiometer with switch - Page 1
Forum section: electronics / projects

author: ballen
author_rank: Regular Contributor
timestamp: December 26, 2022, 03:10:18 pm
content: Is there an easily available small potentiometer (4 or 6mm shaft, with threaded mounting hub) that:(a) will fit into a 16mm diameter circle centered on the shaft, including connections(b) contains an on-off switch and(c) available in a linear 5 or 10kohmsThis is for a one-off, won't be PCB-mounted.This one might just fit if I bend down the connectors:https://www.fk-industrie.de/downloads/files/gifs/RK0962S-30R-4Q-N=7(SW%20asynchronism).pdfThis is the right idea, just slightly too big:https://www.fk-industrie.de/downloads/files/gifs/RK0971S.pdf

author: tooki
author_rank: Super Contributor
timestamp: December 26, 2022, 05:57:42 pm
content: No success looking on Digi-Key, mouser, etc?It took me maybe 3 minutes to find this on Digi-Key:https://www.bourns.com/docs/Product-Datasheets/39.pdfIn stock in 10K with slotted or flatted shaft.

author: ballen
author_rank: Regular Contributor
timestamp: December 26, 2022, 07:28:16 pm
content: Thank you very much! I didn't know that there were 1/8" shaft pots. A search for those using the Mouser filters turned up exactly the model you suggested.

author: tooki
author_rank: Super Contributor
timestamp: December 26, 2022, 09:19:16 pm
content: It’s a pain in the butt how many shaft diameters there are, isn’t it? :p
Small power supply for nixie tube from 3.7V battery - Page 1
Forum section: electronics / projects

author: RawCode
author_rank: Regular Contributor
timestamp: April 19, 2019, 10:32:40 am
content: Hello there!I would like to build a nixie watch like this oneI presume that this kind of watch is powered by a lipo 3.7V battery. Do you have any suggestions on how to build a step-up converter in such a small space? The voltage conversion should be from 3.7V to 170V with a maximum current of 2/5mA for example, because i think that the nixie tubes are multiplexed.I have no experience at all about Nixies and step-up conversion, and this power circuit must be very small, because inside this watch must be a microcontroller to perform RTC functionalities.I searched for small circuits for this purpose and the MAX1771 could be the answer, but i'm not sure how small could it be the circuit and it's also expensive. How about coupled inductor used as micro-transformer?Cheers
small project: Replacing CCFL to LED backlight LCD display - Page 1
Forum section: electronics / projects

author: Kjelt
author_rank: Super Contributor
timestamp: November 14, 2023, 04:11:53 pm
content: Replacing CCFL to LED backlight LCD displaySmall topic for this simple project for those who like to read it or might need it in the future.I got this rather expensive device where the CCFL backlight gave out.The backlight was 150x50mm which is rather big.Even with all the vendors on the web I still could not find a proper replacement.So then you have to choose to take a different approach.I removed the CCFL tube from its mechanical construction.The aluminium tube that hold the CCFL tube is about 4.5mm in diameter.I then searched on the net for 4mm led strips and yes those are available to replace or upgrade 15" to 24" lcd monitor backlighting.You then get two 550mm ledstrips where the white leds are three leds in series and multiple parallel where you can cut between each 3 leds.When it arrived I cut a +/- 150mm length off.Using a powersupply with current control to check at which current I thought I had enough light,since it is battery powered I don't want to waiste too much current.At aprox. 70mA the light was bright enough, the forward Voltage for the ledstrip at that current was 8.4V.My device only had battery power of 4xNiMH so 4.9-5.4V which is insufficient.After struggling with a cheap chinese XL6009 boost converter that needed a short inrushcurrent of 4A to even startup, which is rediculously unusable, I choose an TracoPower TBA1 5V to 9V DC/DC converter of 1W.Since 9V is too much I need a serial resistor which value should be 9V-8.4V = 0.6V / 0.07A = 8.6 ohms.I choose a 10ohm resistor between the output of the DC/DC converter and the led strip and tested it, more then enough light.Then I had to see where I could put this extra converter in the existing housing.I removed the original CCFL inverter and used its pinout and space to fit my backlight pcb.The original CCFL inverter was powered by a MAX603 linear regulator to create 4V.I removed the MAX603 and connected its inputpad to its output pad.The last hurdle was fixing the ledstrip inside the aluminium tube so it was aligned properly with the lightguide.You can use thermal glue but I opted to use some rubberfoam cut a the correct size to keep it properly aligned and it can be removed easily when needed.Now everything fits and works as a charm.

author: inse
author_rank: Super Contributor
timestamp: November 14, 2023, 06:41:23 pm
content: Nice repair.Did you check the primary current of the Traco?Some of those DC/DC converters are ridiculously inefficient.

author: Kjelt
author_rank: Super Contributor
timestamp: November 14, 2023, 08:47:36 pm
content: Yes primairy voltage and current is 5V and 150mA so 0.75WSecondary 9V 0.075A so 0.68W so not too bad. But indeed normal efficiency around 80% but with these small powers I don't mindThe battery is 11000 mAh.
Small repository of user and service manuals - Page 1
Forum section: electronics / projects

author: DTJ
author_rank: Super Contributor
timestamp: September 06, 2017, 06:57:55 am
content: There's a lot of industrial stuff but also some older HP, Megger R&S, Tek, W&Ghttps://isurplus.com.au/user-manuals.html

author: cat87
author_rank: Regular Contributor
timestamp: September 06, 2017, 10:54:48 am
content: Looks like we're not on the guest list

author: tautech
author_rank: Super Contributor
timestamp: September 06, 2017, 11:06:03 am
content: Quote from: DTJ on September 06, 2017, 06:57:55 amThanks, the link worked fine for me.I'll add it to the many others in the sticky in the Repair board:https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/

author: woodchips
author_rank: Frequent Contributor
timestamp: September 06, 2017, 05:47:41 pm
content: Thanks, what an eclectic mix!

author: DTJ
author_rank: Super Contributor
timestamp: September 07, 2017, 01:38:37 am
content: Quote from: woodchips on September 06, 2017, 05:47:41 pmHe sells some really interesting stuff but his prices seem quite high.It's fun to just look through his for sale listings.
Small reuseable stencil frame? - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: December 03, 2017, 07:17:28 pm
content: It's cheap and easy to get small stencils made from places like OSH Stencils, but when you're working with real fine pitch components it can be difficult to keep the frameless stencil and PCB in place when applying.Is there a special type of frame that a frameless stencil can be bolted onto? Or do you just need to always buy framed ones?

author: texaspyro
author_rank: Super Contributor
timestamp: December 04, 2017, 12:07:09 am
content: OSH Stencils sells some "L" shaped plastic thingies that can make an adjustable stencil "frame".You place them on a table top, stick your board in the hole, tape them down, align the stencil to the board, tape it down... voila... adjustable stencil frame. You can also use pieces of PC board material or plastic that is the thickness of your PCB to make a stencil "frame".

author: Koen
author_rank: Frequent Contributor
timestamp: December 04, 2017, 02:18:24 pm
content: Buy 4.95mm steel dowels. Add two 5mm holes to the PCB. The same two 5mm holes to the stencil. Add a note asking the manufacturer not to increase the stencil hole size. Stack 3 PCB together, place two dowels in the stacked holes, place the stencil above. Boom, perfectly indexed and stable cheap frameless stencil.
Small-scale biofuel production - Page 1
Forum section: electronics / projects

author: armandas
author_rank: Frequent Contributor
timestamp: May 11, 2011, 07:26:48 am
content: I have recently finished my master's project where I've been working with three other students on a biofuel production unit. The group was made of two EE and two ME students.I was responsible for designing and building a control unit, that would interface to the electrical system and control motors, solenoid valves and heaters. The result's are quite good, I managed to finish the board, and have written code for most of the hardware features. We have tested the electrical/electronic side in the lab and everything worked fine. The full system run, however, was not permitted by the safety inspector. This has been a running project, so hopefully another group can take over and make some biofuel.I'm attaching some files here, but those who are interested can go tomy websitefor slightly more information.

author: PeterG
author_rank: Frequent Contributor
timestamp: May 11, 2011, 08:06:28 am
content: Nice work.

author: GeoffS
author_rank: Unknown
timestamp: May 11, 2011, 09:45:05 am
content: Nice one.What sort of bio-fuel are you making? diesel or ethanol based?

author: PeterG
author_rank: Frequent Contributor
timestamp: May 11, 2011, 09:53:11 am
content: Going by his website, it is ethanol based fuel.

author: armandas
author_rank: Frequent Contributor
timestamp: May 11, 2011, 11:06:17 am
content: Yes, it was supposed to be ethanol.

author: sacherjj
author_rank: Frequent Contributor
timestamp: May 11, 2011, 01:36:38 pm
content: Quote from: armandas on May 11, 2011, 11:06:17 amI'm sure having a computerized ethanol still would make you the hit of the party in college.

author: armandas
author_rank: Frequent Contributor
timestamp: May 11, 2011, 01:40:04 pm
content: Not sure if people would like the taste of "potato wine", I guess that depends on what one is used to

author: bilko
author_rank: Frequent Contributor
timestamp: May 11, 2011, 01:51:28 pm
content: Distill it again and you get whiskey

author: saturation
author_rank: Super Contributor
timestamp: May 12, 2011, 02:35:48 pm
content: Great work! We need more development to get a small and easy to care for EZ fuel generator like back to the Future's Mr. Fusion; if not realistically fusion why not Mr. Diesel or Mr. Ethanol.

author: armandas
author_rank: Frequent Contributor
timestamp: May 12, 2011, 02:42:15 pm
content: Making its size similar to a dishwasher would be an achievement already!
Small segment LCD on a film, that can be glued on to whatever transparent.. - Page 1
Forum section: electronics / projects

author: JPortici
author_rank: Super Contributor
timestamp: August 30, 2018, 11:50:17 am
content: .. Do they exist?I mean, i'm sure they exist but i wasn't able to find anything like what i have in mind yet.From what i understand any LCD is transparent per se, if we don't have a reflector behind and something that provides the light we should be good to go.I've even seen transparent OLEDs that are very small LEDs on a transparent film (cool!)Basically what i want to come up with is an OSD for my snowboard visori glue the film to the visor, the polarized segments will block the light so i can see speed/altitude/g/whatever

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 30, 2018, 11:52:00 am
content: LCD itself is transparent but needs polarisers to work, so a working unit is never more than 50% transparent

author: JPortici
author_rank: Super Contributor
timestamp: August 30, 2018, 12:28:07 pm
content: probably fine with it, won't know until i try

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: August 30, 2018, 12:28:37 pm
content: Quote from: JPortici on August 30, 2018, 11:50:17 amCan the eye focus on something so close?

author: Ian.M
author_rank: Super Contributor
timestamp: August 30, 2018, 02:07:13 pm
content: Nope. If your myopia is bad enough that you can, your far point is probably so close that you cant count your own toes, so attempting to snowboard without vision correction would be suicidal!What's needed is some sort of imaging projection system that reflects an OLED display off the inside of the visor, with the effective focus at infinity. However HUD optics + finding space to mount it safely isn't so simple. Possibly the best option would be to try to obtain a dead 'Google Glass' like HUD unit you could gut for the optics and display.
Small signal leads - Page 1
Forum section: electronics / projects

author: Filter_head
author_rank: Contributor
timestamp: January 27, 2021, 11:55:36 am
content: Handling small signals in audio question.Two approaches I've seen on commercial hardware using shielded, single conductor instrument wire. In one instance the shield drain wire is connected to the chassis ground. The connection is made at one end of the length of lead only. On other instances, both ends of the drain are attached to the chassis.As an example of the first instance, the drain wire is connected to the RCA panel female outer but at the potentiometer end of the lead there's no drain connection made, the central conductor is attached the pot wiper and the pot ground lead is handled by separate lead wire which might be a 0V reference that, eventually, ties back to the chassis ground at the Earth prong of the AC power entry module.Why is the drain not connected at the potentiometer end of the lead? Is the idea not to "pollute" the 0V reference with a few micro-volts of noise?

author: Terry Bites
author_rank: Super Contributor
timestamp: January 27, 2021, 12:55:07 pm
content: The purpose of the shield is to keep all signals referenced to asinglepotential within and between systems. Essentially ground is a local notion. You cannot trust two "grounds" to be at the same potential (even on the same PCB) unless you design it that way. Ground between one place and another will connect through a finite impedance any current flowing will generate a potential difference that will be added to your signal. This is also possible between different parts of a metal chassis. An most certainly in you power distribution.You want all your grounds at the same potential. For best signal integrity, they should all lead back to a common point in the system. In high impedance scenarios its a good idea to only ground the signal receiving end of the shield and use a separate conductor for signal return. So a tape head would have a shielded pair going to the preamp with the shield unconnected at the head end.BTW Shielding and grounding are not the same thing.https://www.audiosciencereview.com/forum/index.php?threads/ground-loops-101.7162/
small signal test on VFD related electronics? - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: July 03, 2018, 08:57:56 pm
content: So if you wanna buy a cheap old VFD but still have it be reliable, is there any kind of small signal test you can do on the power transistors to see if they are some how degraded? I assume it would be hard to know what the manufacturers operating temperature would be for some kind of ancient drive.Leakage testing? Ron?I thought they might be better documented then the actual VFD if they are identifiable.
Small signal toggle switch - Page 1
Forum section: electronics / projects

author: Hawaka
author_rank: Regular Contributor
timestamp: January 14, 2024, 11:03:04 am
content: Hello,I'm currently building a small signal amplifier. In order to make it more more useful, I would like to have switchable gain stage (On/Off). It will be battery powered, BW around 2MHz.Is there a good alternative to small signal relay, such as a mechanical toggle switch?

author: CaptDon
author_rank: Super Contributor
timestamp: January 14, 2024, 02:45:27 pm
content: When you say band width 2 MHz are you speaking of a D.C. to 2 MHz signal or a signal 2 MHz wide at some base frequency like 10 MHz? A single D.P.D.T. toggle switch may work fine for you. Pay careful attention to grounding the coax or shielded signal wires near the switch to reduce signal leakage. On the center pins of the switch, on side goes to your input connector and the other side to your output connector. In one position of the switch you wire a little jumper so the input directly bridges to the output. In the other position the switch will feed your amplifier from the input side and route the amplifier output to the output side of the switch. I have seen average quality D.P.D.T. switches used in attenuator circuits on commercial products up to at least 10 MHz. Of course a fully shielded coax type switch may be required if you have over 40 Db of gain since without proper shielding you may have self oscillation problems.

author: Hawaka
author_rank: Regular Contributor
timestamp: January 14, 2024, 03:24:33 pm
content: DC to 2MHzThe question is more like would one of these usual toggle switches be good enough for routing the signal either into the gain stage or bypass it? Would wetting current or frequency BW be an issue?

author: David Hess
author_rank: Super Contributor
timestamp: January 14, 2024, 06:16:59 pm
content: Quote from: Hawaka on January 14, 2024, 03:24:33 pmA small printed circuit board mounted switch will be fine up to 2 MHz, but keep the circuit traces short unless they are low impedance. The switch specifications may say if a wetting current is required, but in my experience switches like that never fail in small signal applications anyway.

author: CaptDon
author_rank: Super Contributor
timestamp: January 14, 2024, 06:18:59 pm
content: At the frequencies of interest you could probably use it. If the switch was going to remain in one position for months on end you may develop contact resistance and when switching to the long unused side very poor contact, but simply toggling the switch back and forth about a dozen times should be enough to cure the issue due to the switch having a bit of internal wiping action. I much prefer the mini toggles with the solder tabs to keep signal routing short and using shielded wire right up to the switch.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 14, 2024, 06:33:37 pm
content: Simple mechanical switches will probably work fine at 2 MHz. CMOS analog switches / mutliplexers can go to higher bandwidth but limit your signal range. Those are probably the two most basic options for low speed DC coupled signal switching.
Small Signal vs Full Power BW - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: November 15, 2020, 05:50:47 pm
content: Hi,when it comes to op-amp I always saw only Gain Bandwidth. But in the datasheet of a difference amplifier (see the attached screenshot) there isn't a gain bandwidth but there are two other bandwidths:- Small Signal Bandwidth- Full Power BandwidthWhat are the differences?Which one should I consider?It seems that the Full Power one is when the op-amp output is driven very high, i.e. almost full swing. Is that correct and all or is there something else to it?Full datasheet here:https://www.ti.com/lit/ds/symlink/ina106.pdf?ts=1605462054602&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FINA106

author: David Hess
author_rank: Super Contributor
timestamp: November 15, 2020, 11:50:47 pm
content: Small signal bandwidth is the point where the output falls by 3dB for "small" signals. This is the number that matters for stability considerations. A "small" signal is any signal which does not exceed the maximum slew rate.The full power bandwidth is lower than the small signal bandwidth because it takes into account slew rate limiting of the output, so at high output signal levels, the limited output slew rate limits the output signal level before the small signal bandwidth does. This can be calculated from Full Power Bandwidth = Slew Rate / (2 Pi Vout).Internally what is going on is that for stability reasons, one of the amplifier stages is an integrator and there is a hard limit to the current which can charge or discharge the integrator and this limits slew rate. Externally compensated amplifiers use an external capacitor or network which allows the bandwidth and full power bandwidth to be increased as the closed loop gain is increased so at high gain, they can maintain the same small signal bandwidth and higher full power bandwidth. They may also support feedforward compensation which further increases small signal bandwidth and full power bandwidth. Check out the LM308 datasheet for examples.

author: ricko_uk
author_rank: Super Contributor
timestamp: November 16, 2020, 07:05:36 pm
content: Thank you David!So as long as my signal's slew rate is less than the amplifier max slew rate then I it is ok to consider the small signal bandwidth. Correct?Thank you

author: David Hess
author_rank: Super Contributor
timestamp: November 16, 2020, 07:29:11 pm
content: Quote from: ricko_uk on November 16, 2020, 07:05:36 pmYes, that is correct; as long as you stay within the slew rate, then you can ignore the full power bandwidth.

author: ricko_uk
author_rank: Super Contributor
timestamp: November 18, 2020, 03:41:49 pm
content: Thank you David!
Small TFT LCD price rises - Page 1
Forum section: electronics / projects

author: splin
author_rank: Frequent Contributor
timestamp: October 10, 2016, 04:40:22 pm
content: Just saw this on Buydisplay.com:QuoteMight be a good time to stock up if you use or are planning to use small LCDs - they may become hard to get as well as more expensive. Don't know how long they've had that message up but I didn't see it a couple of weeks ago. I might have missed it though.

author: ataradov
author_rank: Super Contributor
timestamp: October 10, 2016, 05:50:23 pm
content: The problem is that they've been out of stock for at least a month on most small TFT LCDs. So stocking up is not going to happen, really.

author: zephray
author_rank: Newbie
timestamp: October 10, 2016, 10:24:14 pm
content: Actually there are lot many smaller Chinese manufactures are producing these small TFT LCDs. So it should not be a concern.

author: splin
author_rank: Frequent Contributor
timestamp: October 12, 2016, 04:49:59 pm
content: Quote from: ataradov on October 10, 2016, 05:50:23 pmAt least this tells us exactly what this 'Continuity Supply' claim is worth:Quote

author: ataradov
author_rank: Super Contributor
timestamp: October 12, 2016, 04:53:36 pm
content: Quote from: splin on October 12, 2016, 04:49:59 pmThis does not apply to single units. If you had an agreement with them, you are probably getting your parts. The claim is fine. Lead time has increased, for sure. And they have not promised that it is going to cost the same all 10 years, unless you have a contract with them.
Small unipolar stepper motor driver, programmable? - Page 1
Forum section: electronics / projects

author: electronics-whiz
author_rank: Regular Contributor
timestamp: April 10, 2018, 01:57:13 am
content: I recently ended up with an old Pan/Tilt mount for a CCTV camera. I may also be gettin a second very similar one soon too. They were basically going to be tossed because no one knows anything about them and no use for them anymore. The one I have is made by MDK, but I can not find out anything about them, or even what the original controller looked like.I took the one apart and it has a pair of mid size unipolar (6 wire) stepper motors, a few limit switches on the tilt system, an LED/pickup between the base and the turret and a microswitch tripped when it does about 360 degrees. There are two main PCBs, one is a motor driver, the other seems more logic like and has a smaller processor type board on it.Looking at the connection that was labeled control it appears to go to a chip in the base and uses serial connection, then that connects to the logic board. This just seems like a mess to even try to figure out. so i'd like to scrap the original boards for something simpler. I know they make mounts like this still, but these are rated for about 45 LB and a new one costs like $800-$1000. (Although maybe I need to look at this type device in robotics and not camera stuff, but based on the load limit and metal construction that price does not seem like would be easy to get down much.)I was kind of thinking controlling these with a pair of potentiometers, and maybe even USB would be cool. I first thought just use arduino, but not sure if that would work well, or if i'd need adon boards, etc. The device also originally ran on 24V AC. I believe steppers are usually DC and this also had some regulation ceriguits in it to make like 3 an 7V DC.I am just unsure arduino would be the way to go about this or if I would be better with a stepper driver. A potentiometer based system would be nice for a standalone type setup, I think it would be neat to link one to a PC too and maybe add an arm, claw, etc and make a robotic arm of sorts.