hybridfree/eevblog-posts huggingface dataset:
Skip standby mode on power plug in - Page 1
Forum section: electronics / beginners

author: hotter
author_rank: Newbie
timestamp: September 09, 2017, 03:23:03 pm
content: Hi, I have Microlab Solo6C speakers. When I plug them in (raspberry pi does that job with 220 relay) they start in standby mode, so I still need to manually turn them on by turning volume knob.Would it be possible to skip standby mode on plug in? Maybe something like adding a relay inside speaker to imitate turning volume knob once on plug in? Maybe I could power relay from speaker 7segment display, it has power of 1.5V. What would be the schematics to do this?

author: Zero999
author_rank: Super Contributor
timestamp: September 09, 2017, 08:43:25 pm
content: Wht do you mean by running off 1.5V? The specification lists 110V.https://www.amazon.co.uk/Microlabs-SOLO6c-System-Audio-Speaker/dp/B0047CTA1CCan they be turned on using the remote control? Perhaps you could use an IR LED to mimic the turn on signal.

author: hotter
author_rank: Newbie
timestamp: September 09, 2017, 08:50:51 pm
content: 1.5V is supplied to speaker display (7segment 2digit display at the bottom of one speaker) so maybe I could activate relay from it somehow?Yes, they can be turned on using remote control. How could I mimic turn on signal?

author: Ian.M
author_rank: Super Contributor
timestamp: September 09, 2017, 09:12:09 pm
content: Quote from: hotter on September 09, 2017, 08:50:51 pmLIRC. Seehttps://blog.adafruit.com/2017/03/31/make-a-raspberry-pi-universal-remote-with-lirc-piday-raspberrypi-raspberry_pi/
SLA Batteries on their sides? - Page 1
Forum section: electronics / beginners

author: corrado33
author_rank: Frequent Contributor
timestamp: September 12, 2014, 04:35:21 pm
content: Hi all,I've recently scavenged some SLA batteries from our E-waste and was debating putting them into use for an application where they would be mounted horizontally.The batteries say "Valve regulated maintenance free battery."I want to use them as a power supply for my pedal bike (for lights and heated gloves, I'm too cheap to buy a dynamo) but seeing as how they are taller than they are wide, so it's be more convenient to mount them horizontally.Is this ok? I'm getting mixed reports online.

author: potatogun96
author_rank: Contributor
timestamp: September 12, 2014, 04:44:35 pm
content: Because the batteries are sealed, their orientation does not matter. I have a few projects powered by SLA's, and have noticed no negative side effects from being on their side.

author: Fraser
author_rank: Super Contributor
timestamp: September 12, 2014, 04:53:40 pm
content: +1SLA batteries are designed to be orientation insensitive and may be used mounted in any plane.Aurora

author: corrado33
author_rank: Frequent Contributor
timestamp: September 12, 2014, 04:54:33 pm
content: Great, thanks for the info guys.

author: Fraser
author_rank: Super Contributor
timestamp: September 12, 2014, 05:14:45 pm
content: The biggest problem with using salvaged SLA batteries is finding ones that have not sulphated. If an SLA battery is left in a discharged state for more than a few days, sulphation within the plate mats begins. Once the sulphation has reached a serious level, the battery capacity is seriously compromised. Eventually the battery cannot be charged and draws no current. Even if a battery presents 12V across its terminals, it can still be beyond recovery and not charge correctly.I once placed over 200V dc across a sulphated SLA battery and still could not get it to draw any current ! It was just like a capacitor to the supply.Testing SLA batteries is usually done by either an internal impedance test (ESR) or a discharge test into a known constant current load. A very crude test may be done with a load resistor of suitable value.

author: mtdoc
author_rank: Super Contributor
timestamp: September 12, 2014, 05:35:20 pm
content: Because SLA (usually AGM) batteries cannot be equalized which helps prevent sulphation in FLA batteries by mixing (via bubbling) the electrolyte, there is some thinking that SLA actually benefit from periodic changes in their orientation relative to gravity.I have 8 12V 218AH AGM batteries for my PV backup system. They each weigh 132 pounds (about 60kg). So I have yet to test out this theory...
Slave chip not resetting on initialization. - Page 1
Forum section: electronics / beginners

author: Ryu417
author_rank: Newbie
timestamp: September 17, 2016, 04:41:29 pm
content: Been stuck on this initialization problem for a while...I have a master MCU and a slave chip. The MCU pulls a /RESET GPIO pin low on the slave for a full second, then pulls it high, then waits for a ready signal from the slave. My problem is on first power up, the MCU never receives the ready signal - it's waiting for the slave to be properly reset. I know the /RESET pin is going low and then high as it should by measuring the pin's voltage during the initialization...However, if I manually jump the salve's /RESET pin to a ground trace on the board for a moment, and release the jumper, then the slave will boot and send the ready signal! And the slave will continue to be reset fine from the MCU thereafter until power is removed from the system again, and another initial boot is required.I have tried tying the /RESET trace to ground via 100k ohm resistor, as well as to VCC.I don't know where to start diagnosing this, so thanks in advance for any comments.Context: Board is a two-layer PCB I designed myself. SMT components. I am in no way a professional at circuit design..

author: rstofer
author_rank: Super Contributor
timestamp: September 17, 2016, 05:02:07 pm
content: Which MCU? MCU code? Which peripheral? Schematic?

author: Connoiseur
author_rank: Regular Contributor
timestamp: September 17, 2016, 05:04:40 pm
content: What voltages did you get when you measured the two states (viz high, low) of the pin?As pointed out by rstofer, schematic of your project will be greatly useful for any suggestions.

author: Ryu417
author_rank: Newbie
timestamp: September 17, 2016, 07:07:21 pm
content: QuoteThe slave chip is a vs1063 audio decoder. Schematic attached. It interfaces with an SD card connector along with the MCU over SPI. It's the "MP3-RST" pin that is in question here. If I jump it to ground, it seems to reset the chip fine.The MCU is a Atmel 1284p in a "minimalistic Arduino" configuration. Basically just crystal and supporting capacitors and such. Using SPI for communication with the slave chip and SD card.In the schematic attached, R16 and R17 are not used together... I just made the footprints to use either one or the other for trial and error, but never both at once. I have tried each configuration now without luck.QuoteWith reference to a ground trace on the board, I've measured a solid 3.3V as well as 0.00V on the /MP3-RST pin

author: rstofer
author_rank: Super Contributor
timestamp: September 17, 2016, 09:59:38 pm
content: Darned if I know...OK, you pull RESET low which floats DREQ (probably goes high). Then you pull RESET high and DREQ will then go low for 22,000 cycles (1.8 ms). Finally DREQ should go high. Don't test DREQ until after RESET has been high for at least 1 ms. Maybe wait 2 ms...I might use the pull-down resistor on DREQ but I might not. If the code is working properly, the fact that DREQ floats around during reset wouldn't make any difference because I wouldn't be looking at it for quite some time after RESET returns high.
sleeve tubing thats not heat shrink?  - Page 1
Forum section: electronics / beginners

author: peps1
author_rank: Regular Contributor
timestamp: November 27, 2013, 02:15:24 pm
content: Hey,I need some sleeve tubing for transistor legs that is not heat shrink, and as I need to do a couple of hundred I don't want to just strip wire for the sleeving and have all the waste bare wire.Is it possible to get lengths of just the sleeving anywhere?

author: robrenz
author_rank: Super Contributor
timestamp: November 27, 2013, 02:18:23 pm
content: google Kapton tubing and or spaghetti tubing

author: Crazy Ape
author_rank: Regular Contributor
timestamp: November 27, 2013, 02:23:22 pm
content: Some here.http://www.adtech.co.uk/TubePage.html

author: peps1
author_rank: Regular Contributor
timestamp: November 27, 2013, 03:10:18 pm
content: Quote from: robrenz on November 27, 2013, 02:18:23 pmThank you,Loving the vintage varnished Spaghetti tubing (shame its so expensive!)

author: ConKbot
author_rank: Super Contributor
timestamp: November 27, 2013, 08:34:47 pm
content: http://uk.farnell.com/pro-power/stfe22-5mnat/sleeving-ptfe-5m/dp/1191042plenty of varieties available on farnell
Slew Rate Limiter Circuit Question - Page 1
Forum section: electronics / beginners

author: chancs
author_rank: Contributor
timestamp: August 21, 2020, 06:47:35 pm
content: I have a project in mind that might need to very the slew rate of the DAC output (any where from 1mV/uS to 1V/uS). A quick googling shows this reference design by TI (https://www.ti.com/lit/ug/tidu026/tidu026.pdf). Then I went on built the circuit in PSpice for TI.The following figure is the simulation result running on Vsupply +/-12V. Green trace is the "DAC" output and the yellow trace is the output of the slew rate limiter. I am not sure why the slew rate doesn't get limited at the beginning for the rising/failing edge, which circled by a red square.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 21, 2020, 09:39:05 pm
content: Some amps do that, though it shouldn't be at this small signal level, and I don't see any evidence that this particular amp has the behavior. (It is suspicious that the plots show small-signal step response for inverting and noninverting configurations, but large-signal only inverting.) Maybe it's a model error, or try adjusting simulation parameters too.Tim

author: MasterT
author_rank: Frequent Contributor
timestamp: August 21, 2020, 11:21:40 pm
content: R2 defines step, try R2 = 0.

author: chancs
author_rank: Contributor
timestamp: August 22, 2020, 07:16:12 am
content: Thanks for the advice. Reduce R2 does lower the quick increase in voltage.I am guessing it has something to do with R1 and R2 form a voltage divider?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 22, 2020, 08:54:37 am
content: Yes, there is a divider from VCC/VEE (railed opamp) to -in to output. Just now realizing that's the voltagewhich explains the modest offset even given the high ratio, and it's no accident of simulation or construction.R2 is probably needed to keep the two-amp loop stable. You'll have to decide how much step is acceptable. Perhaps the first amp can be compensated instead, but mind this will slow its own output, i.e. there will be some toe-in before the maximum slew rate is attained.If you require a no-step option, perhaps consider an operational transconductance amplifier (LM13700) in follower configuration, with capacitance on the gain node; the programming current and capacitance set slew rate. (This has rather mediocre offset (a few mV), which can be improved by wrapping it with a precision amp in much the same way as above.)Tim
Slide 0951 of the book : Analog Design Essentials - Page 1
Forum section: electronics / beginners

author: promach
author_rank: Frequent Contributor
timestamp: October 22, 2019, 02:03:31 am
content: I am reading the bookAnalog Design EssentialsHowever, the attached slide 0951 on the book pdf is so unclear.Could anyone upload the same slide with higher sampling resolution ? Thanks !!!I found the hardcopy book, yet the titles (FOM and IFOM) are still not clear even on the hardcopy book itself

author: promach
author_rank: Frequent Contributor
timestamp: October 22, 2019, 04:09:42 am
content: Found it with someone else help.
Slide potentiometer pin configurations - Page 1
Forum section: electronics / beginners

author: ashwinsawant
author_rank: Newbie
timestamp: February 28, 2017, 03:29:21 am
content: Hello,I am trying my first repair - trying to replace a broken slide potentiometer on my PB-503 prototyping board. I ordered a replacement part, but it's pin configuration seems to be the mirror image of the part on the board. I have attached a picture of them side-by-side. Do slide potentiometers come in left- and right-handed configurations, and how can I tell before I order one online? Or is it just a custom part and I'm out of luck?

author: dacman
author_rank: Frequent Contributor
timestamp: March 01, 2017, 12:05:18 am
content: The better (IMO) part suppliers have datasheets on most all items (Newark, Digi-Key, Mouser, Allied Electronics, OnlineComponents, Grainger, etc.).

author: ashwinsawant
author_rank: Newbie
timestamp: March 17, 2017, 02:55:29 pm
content: Thank you for the tip - I reviewed the data sheets and found an appropriate part.
Slide Switches AC/DC current rating question - Page 1
Forum section: electronics / beginners

author: SebG
author_rank: Regular Contributor
timestamp: May 30, 2013, 09:15:00 am
content: For a project I'm working on I need a slide switch to select between two current paths. (Max 2.5 Amps DC)Most switches I find are rated for 4 or 6 Amps at 125 VAC but only like 0.5A at DC.Why is that?If I use such a switch in my project what kind of things would the the effect of passing high DC Current through the switch?The contact look sufficient to conduct such a current but i don't understand why they have such a low DC rating and high AC rating.The DC voltage maximum would be 20V and the switches would be positioned before current begins to flow, most of the time.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 30, 2013, 09:20:58 am
content: Quote from: SebG on May 30, 2013, 09:15:00 amThe reason switches have lower ratings at DC, especially as voltages increase, is that DC arcs don't self-extinguish - with AC, any arc formed at opening will stop at the zero-crossing and not restart. A DC arc will just keep burning until the contact seperation is too big to sustain it (which may be never).

author: SebG
author_rank: Regular Contributor
timestamp: May 30, 2013, 10:18:41 am
content: This if very interesting and it explains a lot. Thanks.
Slow I2C EEPROM writes - Page 1
Forum section: electronics / beginners

author: SlowBro
author_rank: Regular Contributor
timestamp: January 15, 2018, 07:21:10 pm
content: What can I do about what seems to me to be super slow EEPROM writes? It's writing 15KB of data at about 1.5kbps over a 400 kHz connection, taking about 80 seconds. But the same data can be read off in 4.7 seconds, at a more respectable 26kbps. This is well short of 400 kHz but still far faster than writing.Platform is a Raspberry Pi Zero W running Raspbian Stretch Lite connecting to an Atmel 24C256 at 3.3V connecting using a pair of 24 gauge stranded wire breadboard jumpers. This is the only device on the bus and it isspec'd to run up to 400 kHz. I'm usingthis eeprogcode.Best I can tell that program does not support paged writes; However, according tothis, paged writes don't make any difference in speed. Besides, if writes are not paged then I would also expect reads would not be paged either, and yet they are so much faster. Unless I'm just missing something.I don't know how to test my I2C bus for noise but I would suppose it's clean enough because I can read at a much faster speed than write. I wouldhappilyaccept 26kbps.On a hunch I dropped to 40 kHz as a test to see how it impacted behavior. It added about 13 seconds to write and 18 seconds to read. So write speed dropped to 1.2 kbps and read speed to 11.2 kbps.Command used:time eeprog -16 -f -q -w 0x40 -t 5 -i /tmp/test_file /dev/i2c-1 0x50

author: Signal32
author_rank: Frequent Contributor
timestamp: January 15, 2018, 10:23:03 pm
content: That means you can do max 200 writes / sec. If you use page writes @64bytes/page you can get max 12.8kb/s. It will prob be higher as the 5ms spec is the max that you can expect.Where does the link say that page writes don't affect speed. I see it says this:QuoteFrom the code of the tool that you're using:So 1.5kb/s is actually very good, you should be seeing 200b/s.

author: SlowBro
author_rank: Regular Contributor
timestamp: January 15, 2018, 10:45:49 pm
content: Quote from: Signal32 on January 15, 2018, 10:23:03 pmCrap. Well thanks for the help on that.
Slow LED with 2N7000 and demux - Page 1
Forum section: electronics / beginners

author: analogo
author_rank: Regular Contributor
timestamp: June 06, 2017, 07:52:19 pm
content: Dear forum, why do my LEDs light up so slowly (about 2 seconds to full brightness) when I use a demux to drive a N-channel MOSFET?I have several LEDs that I would like to light up in a complicated order (matrix, charlieplexing and similar stuff). To drive my LEDs I use an MCU to command a 3-to-8 demux that, in turn, switch on and off a set of N-ch MOSFETs. My circuit and my MCU program work fine with one exception: the LEDs take about two seconds to light up completely. I have attached the schematic of the most reduced circuit that exhibits this problem. I also made asimulated version online.I cannot understand why the LEDs are so "slow". They require between 1 and 2 seconds to start up. They respond much more quickly (but still slowly: 0.5 seconds) if the circuit has been going on for a minute or so. I suppose there is some (huge) capacitance somewhere, but where? In the demux?If I remove the demux and I connect the gate of the 2N7000 MOSFET directly to the +5v rail, the LEDs will switch on and off instantly. So I am led to think that, somehow, the demux output is responsible for this slowdown. However, thedatasheet of my TI CD4051says that the output channels have only 30pF of capacitance and a typical 30 ns of propagation delay.What else could cause this slowdown?

author: BradC
author_rank: Super Contributor
timestamp: June 06, 2017, 08:00:03 pm
content: Where is the inhibit pin and what are you doing with it. What are you doing with the other 2 multiplex select inputs?

author: analogo
author_rank: Regular Contributor
timestamp: June 06, 2017, 08:13:50 pm
content: Quote from: BradC on June 06, 2017, 08:00:03 pmThe inhibit pin is always grounded (= demux is always on).Normally all the inputs are wired to a MCU pin, but I can replicate this problem by grounding all of them and adding a button connected to +5 on the A select input, taking the MCU out of the equation.Vcc is connected to +5; Vee and Vss are both grounded. COM is connected to +5v.

author: analogo
author_rank: Regular Contributor
timestamp: June 06, 2017, 08:31:20 pm
content: Quote from: analogo on June 06, 2017, 08:13:50 pmAh ah, not so fast. Properly grounding INH was, indeed, the fix to the problem. Same with the MCU code, I removed all the calls to enable/disable the demux.Thank you BradC for putting me on the right track. But where does this strange behaviour come from? The datasheet says that the inhibit-to-signal delay is only 400 ns. Basically nothing for this kind of application. How do we get from 400 ns to 2 seconds?

author: BradC
author_rank: Super Contributor
timestamp: June 06, 2017, 08:36:56 pm
content: Quote from: analogo on June 06, 2017, 08:31:20 pmIt's not a delay as such, more leakage. Having said that if your gate on the fet is really pulled down with 100K then I don't quite get it, but stranger things have happened.
Slowing down the simulation speed in proteus? - Page 1
Forum section: electronics / beginners

author: ChemroukO
author_rank: Newbie
timestamp: April 20, 2018, 06:26:01 pm
content: Hello everyone,I am currently using Proteus 8.4 & I liked it a lot. But, sometimes it fails to run the simulation properly (Exceeding Cpu) & it starts to lag.Can't I reduce the simulation speed (from real-time x1 to something like x0.5) as what can be done in NI multisimThanks a lot.
SM DC power supply, earth reference or float? - Page 1
Forum section: electronics / beginners

author: wobblycogs
author_rank: Contributor
timestamp: December 28, 2021, 12:29:45 pm
content: I'm building an RGB LED lamp around WS2812b strips. The lamp will comprise 16 strips of 16 LEDs for 256 LEDs in total. The strips will be mounted in a square arrangement on a 3mm aluminium plate. On the back of the plate will be mounted the power supply (switch mode, 20A @ 5V) and other components (Raspberry Pi Zero, logic level shifter and boost converter for a 12V cooling fan).As this will be a mains powered project the aluminium plate should be connected to the mains earth. The outer case of the power supply is connected to earth and therefore when I screw the power supply to the aluminium plate it too will the earthed - this I'm happy with. The question I have is should I also connect the DC negative to earth with a jumper cable or leave the output floating? My understanding is that it will work (and should be safe) either way but I want to be sure that is correct.As I understand it referencing the DC negative to earth stops the output side of the power supply floating to unsafe voltages (relative to earth), it makes fault finding easier and it helps to avoid interference. The main downside of referencing to earth seems to be the danger of shorts from DC positive to earth which, if I understand things correctly, won't trip an RCD (but should blow a fuse on the output side). Since I'm only dealing with 5V on the output side I'm not worried about electric shock from that but I am worried about burning the house down. Other than the reduced risk there doesn't seem to be much benefit to letting a circuit like this float.Many thanks for any help.

author: wa2pux
author_rank: Contributor
timestamp: December 28, 2021, 03:15:57 pm
content: My preference has always to ground reference the return path of the output of a power supply unless there is a good reason not to.This just keeps everything on the same level.So, the answer is, if you don't have a real good reason to keep it floating, I'd ground the power supply return.

author: wobblycogs
author_rank: Contributor
timestamp: December 28, 2021, 05:41:07 pm
content: Many thanks, that was pretty much the conclusion I'd come to.Electronics is surprisingly hard to get into, there are so many competing factors with even simple circuits.
SMA connector construction/anatomy and materials - Page 1
Forum section: electronics / beginners

author: matthuszagh
author_rank: Frequent Contributor
timestamp: April 18, 2023, 04:52:23 am
content: I'm looking at Huber+Suhner cable-mount SMA connectors and there are a number of different options (for the same cable) that use different materials and differ in price. I'd like to understand the parts of the connector that each anatomical description refers to as well as the tradeoffs of using different materials (and platings) for each of these parts (I'm just interested in the metal materials, not the dielectric).For reference, I'm including a cross-sectional picture of mated SMA connectors, labelled according to the parts I think I know.I'll additionally be referencing the following connector datasheets (in order of ascending cost on Mouser, from about 9USD to 13USD):-https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_56199_NH_DataSheet-2582581.pdf-https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_46133_NE_DataSheet-2581951.pdf-https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_6111_NH_DataSheet-2582519.pdf-https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_56199_NE_DataSheet-2582056.pdf-https://www.mouser.com/datasheet/2/829/HUBER_2bSUHNER_11_SMA_50_3_6111_NE_DataSheet-2581919.pdfThe datasheets reference:- center contact (labelled 1)- outer contact (labelled 3)- coupling nut (labelled 2)- insulator/dielectric (labelled 4)- crimp ferrule (crimped part shown in the other image)- body (??)- gasket (??)What are the body and gasket? Where are these in my images?Now onto materials.I've heard that Copper Beryllium Alloy is a high-quality contact material. I've also heard that higher quality SMA connectors tend to use stainless steel over brass (and that SS should be torqued to 8in-lb vs 5in-lb for brass). Is that true? I expect this was in reference to the coupling nut, but I don't know.Some of the lower cost connectors I linked use stainless steel for the outer contact (inner contact uses beryllium copper). Wouldn't SS be a horrible material for the outer contact? I would imagine that needs good electrical conductivity. By contrast, some of the more expensive ones use gold-plated brass for the coupling nut. That would seem to contradict my preconceptions above. I would have expected something like beryllium copper for the center and outer contacts and SS for the coupling.Does the conductivity of the of the coupling nut matter? I had thought the current return path was through the outer contact, not the coupling nut.
Small but interesting PSU - Page 1
Forum section: electronics / beginners

author: paul18fr
author_rank: Contributor
timestamp: October 09, 2014, 04:55:03 pm
content: Here is a small but interesting PSU to start with, isn't it ?http://www.instructables.com/id/DIY-Small-Bench-Power-Supply/?ALLSTEPS

author: zapta
author_rank: Super Contributor
timestamp: October 09, 2014, 05:18:48 pm
content: Quote from: paul18fr on October 09, 2014, 04:55:03 pmCute. I would buy one (with integrated AC/DC).
Small Batch of PCBs - Page 1
Forum section: electronics / beginners

author: Stephen1424
author_rank: Newbie
timestamp: October 07, 2013, 06:36:52 pm
content: Would it be cheaper for me to Personally etch a small run of boards or have a company do them for me ?Not looking for production, just a couple.Small boards, like less than 4" square.

author: Metalcrowe
author_rank: Contributor
timestamp: October 07, 2013, 07:02:06 pm
content: Hello,I can recommendhttp://imall.iteadstudio.com/open-pcb/pcb-prototyping/im120418001.html.They are really cheap and have a good quality.Greets

author: fenclu
author_rank: Regular Contributor
timestamp: October 07, 2013, 07:03:05 pm
content: You can get 10 5x5cm PCBs from ITead Studio for ten bucks. It would probably be more expensive to buy all the stuff you need to etch them yourself. Plus, you end up with pretty much professional boards.

author: wbooth.clearscene
author_rank: Contributor
timestamp: October 07, 2013, 07:09:00 pm
content: It depends on if you have access to the equipment to do etching. If you do, then etch you're own.If not then it's gonna be best to get it done externally.Personally, I've been using a guy on ebay (in the uk) that mills board traces on a cnc machine. Cheep and good quality for small runs.

author: Stephen1424
author_rank: Newbie
timestamp: October 07, 2013, 08:04:04 pm
content: Thanks for all the great suggestions, ill check them out

author: Janaha
author_rank: Newbie
timestamp: October 07, 2013, 08:35:06 pm
content: Hy.I realy have given up on etching my pcb's at home. I have on of those etching bathes where you use a heater to heat up a solution of natriumpersulfat to etch away the unwanted copper on a pcb. I ruind some of my trousers by etching away some of the cotton :-). And all for some prototypes. I used a Brother Printer to print the designes on overheadfoil and a uv-exposure unit to bring it to the photo sensitive boards. But the printer dosen't print the traces good enough so. So every two to three boards i made are failures for the waste bin.By now i order the board at iteatstudios like mentioned above. So i get my board realys quick and in quantities and qualities i can't achive with my gear at home.GreetingsJanaha
Small battery tester - Page 1
Forum section: electronics / beginners

author: 6PTsocket
author_rank: Regular Contributor
timestamp: February 04, 2019, 04:43:06 pm
content: There are plenty of cheap voltmeter testers that apply a load to the AA, AAA, 9V, button cell, etc., and read good, weak, bad. I realize that the load is an approximation of the actual load a battery may have to power might be higher or lower. I would like to build a little load box for my DMM. Is there some reference listing what lists reasonabable test load currents for various small batteries and the percentage of fresh voltage that constitutes good, weak or bad?The project is super simple but I need some data. I am not sure it is on battery spec. sheets.Sent from my SM-G900V using Tapatalk

author: ender4171
author_rank: Contributor
timestamp: February 04, 2019, 05:51:52 pm
content: This ANSI doc covers a ton of info for alkaline batteries, including testing methods and measures. I didn't read through the whole thing, but check pages 9-11 for some data. There is likely more later in the document or in related ANSI docs. It's a place to start at least. So are datasheets for "example" batteries of the type you wish to test. PDF Warning:https://www.batterybob.com/Battery-Reference/ansi_c18_1part1.pdf

author: Wimberleytech
author_rank: Super Contributor
timestamp: February 04, 2019, 11:01:51 pm
content: Quote from: ender4171 on February 04, 2019, 05:51:52 pmGreat reference. Thanks for sharing!

author: 6PTsocket
author_rank: Regular Contributor
timestamp: February 04, 2019, 11:06:50 pm
content: ende4171 thanks for that link. It's all there. They suggest several applications for a given cell eg: toy, flashlight, remote, etc. Then they give the estimated load in ma, and ohms for each application and the terminal voltage for that application. For 1.5V alkalines it ranges from .8 to 1volt for end of life. The only trouble is they use industry terminology rather than the common names. An LR3 is what we all call a AAA. With so many types, I should probably make a chart and install a multi turn pot in a little box with a metal pad and one test lead. Switch to ohms, set pot, switch to volts, test. Yes, I know it is a good way to zap the ohms scale in the DMM. Thanks again.Sent from my SM-G900V using Tapatalk

author: Doctorandus_P
author_rank: Super Contributor
timestamp: February 05, 2019, 07:52:02 am
content: I like this idea for a "small battery tester":The thing itself is a charger instead of a tester, but the idea is still the same.It has 2 magnets that stick to your battery.Discharge currents for testing a battery are not very critical. As you probably already know an (almost completely) empty battery can still have near it's nominal voltage when measured with a high impedance source, but the voltage collapses significantly under any load.Anything between a few mA and an Amp is probably ok, but you may study the documents linked above for more accurate data.
Small beginner reflow oven for Australia - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: June 26, 2017, 07:21:10 am
content: Hi All,I want to pickup something for a beginner to do a low volume (hobby) small boards safely and with good results, budget is $1000 AUD so something better than the cheap chinese aliexpress stuff, it needs to be $1000 including shipping/duties/taxes to Australia, is there anything?I would rather it comes ready to go.Thanks.Richard

author: David_AVD
author_rank: Super Contributor
timestamp: June 26, 2017, 09:03:39 am
content: If you're using leaded paste the Breville BOV800 toaster oven works well. Been using it for a couple of years. There may be a newer model these days of course.

author: rthorntn
author_rank: Frequent Contributor
timestamp: June 26, 2017, 09:25:09 am
content: Lead free solder paste would be much better.Is there a gap in the market here between $300 Chinese ovens and $2000+ pro ones?

author: gamalot
author_rank: Super Contributor
timestamp: June 26, 2017, 09:33:00 am
content: Quote from: rthorntn on June 26, 2017, 09:25:09 amI used to use a $300 reflow oven to manufacture PCBA for our Japanese customer when I worked in my hometown in China.

author: rthorntn
author_rank: Frequent Contributor
timestamp: June 26, 2017, 11:37:40 am
content: I read somewhere on EEVblog that the cheap Chinese machines needed a more height, better heat distribution and a better control system...Nothing half decent for $1000 then?

author: David_AVD
author_rank: Super Contributor
timestamp: June 26, 2017, 11:47:03 am
content: So this is for hobby use but you want lead-free ?

author: rthorntn
author_rank: Frequent Contributor
timestamp: June 26, 2017, 12:21:35 pm
content: The lead free requirement came from the environmental impact of lead.

author: rstofer
author_rank: Super Contributor
timestamp: June 26, 2017, 01:48:29 pm
content: I use a Black & Decker Infra-Wave Toaster Oven but I believe it is out of production. It has 4 lamps, 2 on top and two on the bottom.To get the heat cycle to work, I had to add high temperature insulation between the inner and outer walls. I bought this as a sheet and just cut it to fit.For control, I used an Arduino Reflow Oven Shield as the control system. I'm not sure how it works with lead-free solder as I am using leaded. There is nothing in the law (in the US) that says I have to use lead-free solder for personal projects.http://www.rocketscream.com/shop/reflow-oven-controller-shield-arduino-compatible
small connector for cmos camera sensor - Page 1
Forum section: electronics / beginners

author: vasilistzo
author_rank: Newbie
timestamp: January 29, 2015, 06:50:08 am
content: Hi allI want to cool a cmos camera that i m using at the moment for noise reduction in long exposure images.My plan is to attach a peltier at the back side of the sensor. The sensor board is connected to the processor's board with a small connector that i havent seen before and i m going to try to find some extension cable so i can have some clearance between the 2 boards.Does anyone know the type of the connector??I am attaching a few pictures of the boardMany many thanks

author: poorchava
author_rank: Super Contributor
timestamp: January 29, 2015, 06:59:42 am
content: I'd look around at websites of usual suspects: Tyco, Amphenol, Hirose, Molex, Samtec, Binder, 3M.There is a good chance though, if that samera was salvaged from something, that the mating connector is virtually unavailable in single quantities. Perhaps you'd be better off removing the connector and soldering a ribbon cable to the footprint?

author: vasilistzo
author_rank: Newbie
timestamp: January 29, 2015, 07:03:41 am
content: I m looking at the websites but no luck.The camera is brand new so i ll give it a second thought and a few days of searching before soldering the ribbon cable.Thanks a lot
Small connectors table? - Page 1
Forum section: electronics / beginners

author: Zbig
author_rank: Frequent Contributor
timestamp: June 03, 2014, 04:59:58 pm
content: Does anyone know of any resource with names and pictures of various small cable connectors gathered together? You know, like those ubiquitous small white (usually) plugs with crimped connectors, found inside almost any electronic device (often for fans). Or used in R/C hobby. I know there are various types of JST (eg. JST-XH), Molex and others. But I always have a hard time identifying them and find it rather frustrating as they often seem to differ in the details of the latch only, etc.For instance, what's this one called?EDIT:Ok, that'd be, in fact, JST-XH, I guess. The question is still valid, though, as find it a bit of a nuisance having to figure it out for each and every of the almost identical little guys.EDIT 2:Oh, and the JST isn't a brand name but an acronym for Japan Solderless Terminal. Cool, who would have thought.

author: PointyOintment
author_rank: Frequent Contributor
timestamp: June 06, 2014, 08:30:18 am
content: Looks like you've already found the Wikipedia article, which has a table of some of them, but without pictures of each. The closest thing I was able to find wasthis RCGroups thread.

author: xquercus
author_rank: Contributor
timestamp: June 06, 2014, 03:47:36 pm
content: I hope someone chimes in with a comprehensive description of inline wire to board connectors but I'm doubtful such a thing exists. What you are asking for is particularly useful when it comes to repair and you want to find a matching connector. It sounds like you are trying to find replacements for repair. I've been there and the best solution I've come up with is to start at the top level of the various manufacturer's wire to board connector catalog. For example:http://www.jst-mfg.com/product/pageview/connector_e/pageview.html#page_num=2http://www.molex.com/molex/products/group?key=wire_to_board_connectors&channel=productsOne of the keys is to measure the center to center pin spacing. That will help eliminate the majority of connectors.Sometimes, it's just not possible to find a replacement connector. In that case, I've just gotten the through hole pin spacing for the board connector and replaced both the plug and socket with a similar product. Some connectors can be purchased with preterminated pins. Even though they are expensive, I think it's worth considering buying pre-crimped pins if possible.
Small Current - Page 1
Forum section: electronics / beginners

author: radhika
author_rank: Regular Contributor
timestamp: August 28, 2018, 10:44:52 am
content: Hello,I am working on current amplifier and I want 2A as a output from 250mA Arduino Input.According to the transistor 2N3055 Ib = 40mA for Beta = 50For getting 2A as a output from 2N3055 I have to get Ic = 80mA at 2N2222 and Rc = 50 ohm also, Ib = 40mA at 2N3055. But I can't get the required output.I get 2A at Rc = 10 Ohm at 2N2222 and 10Ohm is so small. I don't have this small resistor. Can It be possible to get 2A for normal Ohm ( 22 Ohm to 10K Ohm ).P.S. I am new to electronics.

author: Rerouter
author_rank: Super Contributor
timestamp: August 28, 2018, 11:01:31 am
content: I would like to remind you that you can use 2x 22 ohm resistors in parrellel for 11 ohms,I would say if you just want to switch 2A, a suitably sized mosfet may be better suited, but if All you have is a 2n2222 and a 2n3055, then sure, lets get it switching,the 2n2222 has a beta (current multiplication more or less) of atleast 100, so for every 1mA in, you get 100 through the transistor,the 2n3055 has a beta of atleast 20,Lets say we hook them up as a darlington pair, this will drop some voltage, but will make it easy to get the amount of current,So to switch 2A with the 2n3055, you need atleast 100mA into its base, so your 2n2222 needs atleast 1mA into its base,https://www.kitronik.co.uk/blog/how-a-darlington-pair-transistor-works/

author: radhika
author_rank: Regular Contributor
timestamp: August 28, 2018, 11:03:54 am
content: https://postimg.cc/image/c4x1d5wzb/This is the Darlington pair I have used

author: Rerouter
author_rank: Super Contributor
timestamp: August 28, 2018, 11:12:41 am
content: Should probably be more like this.

author: radhika
author_rank: Regular Contributor
timestamp: August 28, 2018, 11:56:36 am
content: Hello,Thank you so much for guidance. It really helpful. And I even got the result for 1A. Now, I am working on 2A too.But I have a question. i.e. 2N3055 outputs at VCE = 2V. And in my circuit their is no resistor to get Vce 2V. Is this make it unstable?Also, if I make Vce = 2A then, Vcc - Vce - IcRc = 0, so, (5-2)/1A = 3 Ohm. Hence it again give me 3Ohm which is so small. How do I solve this problem?

author: Rerouter
author_rank: Super Contributor
timestamp: August 28, 2018, 12:27:04 pm
content: When you feed lets say 3.3V into the resistor, the 2n2222 will drop 0.7V across its base-emmitor junction, and the 2n3055 will drop an additional 0.7v to ground,So your 2n2222 base will be at about 1.4V, and the 2n3055 collector will be at about 0.7V because its limited by the base-emmitor junctions voltage. this is a limit inherent to darlington pairs.If you want close to a 0V drop, it would require something like an N channel mosfet,

author: radhika
author_rank: Regular Contributor
timestamp: August 28, 2018, 01:05:11 pm
content: Thank you so much Ma'am/Sir I will take care of it. You really help me a lot
Small dimension supercap? - Page 1
Forum section: electronics / beginners

author: kalel
author_rank: Frequent Contributor
timestamp: August 07, 2017, 03:03:47 pm
content: I thought about possibly making something inspired by this:I have a ~10mm/0.39 inch inside diameter plastic tube of sorts. A slightly larger diameter one also, but it would require larger diameter magnets (so more expensive) to fit properly.I'm considering the lowest budget option for parts - as the project is only a small experiment to see how well it works.I would like to ask anyone that might know a few questions:- Is there a small enough capacitor that might be suitable enough which could fit inside of the tube? Probably not, but worth asking about, as having most of the electronic components inside would be great. If only the LED was sticking out, that would be optimal, but obviously might not be simple.- What kind of LED would be optimal? A 10mm one seems great and looks great for a flashlight, but I'm wondering about efficiency. Would it work better, worse or comparable if a higher power LED was used? E.g. one of those 1-3w LEDs with heatsinks, with a lens added, but ran at an equal or similar current that the 10mm one would use.Parts will be from China, so getting exact schematics is sometimes possible, but not always easy.

author: Zero999
author_rank: Super Contributor
timestamp: August 07, 2017, 08:59:23 pm
content: This looks better than the cheap and cheerful hand crank lamps, which break fairly quickly.What's your question?

author: kalel
author_rank: Frequent Contributor
timestamp: August 08, 2017, 08:29:02 am
content: Quote from: Hero999 on August 07, 2017, 08:59:23 pmYes, it was unclear so I reformatted the entire main post. Thanks.
Small engine tach from DMM - Page 1
Forum section: electronics / beginners

author: 6PTsocket
author_rank: Regular Contributor
timestamp: August 31, 2018, 07:35:11 pm
content: I was going to buy a small engine tach. All the engines are either 1 cyl, 2cycle or wasted spark 4 cycle. That is one pulse per revolution. I set my DMM to frequency and just grounding the negative lead to the engine and stray pickup to the positive lead (antenna) was enough to get pretty stable readings. The problem is I am reading pulses per second, not per minute. It is not practical to keep dividing by 60 in my head. I see there are any number of divide by N chips but I have no familiarity with them. Also the divider might not be as sensitive to stray pickup as the DMM so maybe I would need some amplification on the front end. Any suggesrions appreciated. Thanks.Sent from my SM-G900V using Tapatalk

author: xani
author_rank: Frequent Contributor
timestamp: August 31, 2018, 08:02:02 pm
content: QuoteI think you've meant multiplying ? Dividing digitally is easy, multiplying is a bit of work.Easiest option: frequency counter with RPM mode. Or a "car" multimeter with similar option.Cheapest option: An Arduino (or any other tiny micro), any display and a bit of circuitry (could probably be done with schmitt trigger and few diodes)Loopiest option: Get acquainted with PLLs and design x60 multiplier. Or cheat, and program a micro to measure a frequency and then generate one that's x60 of thatWonkiest option: Go to aliexpress and look for chinese tachometers

author: John B
author_rank: Frequent Contributor
timestamp: August 31, 2018, 08:39:46 pm
content: I built a tacho for my own car using arduino. The standard arduino library isn't suitable for measuring high frequency, use these instead:https://www.pjrc.com/teensy/td_libs_FreqCount.htmlUsing a micro gives you more options for smoothing the signal and types of output. You might want to drive an LED display, in my case I had to drive an air core tachometer so it involved RPM -> PWM -> 2-6V DC level

author: 6PTsocket
author_rank: Regular Contributor
timestamp: August 31, 2018, 08:47:25 pm
content: Yeah multiply. My bad. It seems it may not pay to try and use the DMM frequency feature even though it is picking up so well.Sent from my SM-G900V using Tapatalk

author: Brumby
author_rank: Unknown
timestamp: September 01, 2018, 01:53:18 am
content: Quote from: 6PTsocket on August 31, 2018, 08:47:25 pmIt's cheap (zero extra cost) and it works. It's also a single piece of kit - which is less to carry and less to go wrong.Keep using it and you'll soon be able to multiply a whole range of values by 60 in your head.The idea isn't new - there have been scale doubler ranges on some analogue meters in days gone by. Sure, dividing by 2 is easier, but it is a mathematical process nonetheless.

author: JS
author_rank: Frequent Contributor
timestamp: September 01, 2018, 05:02:20 am
content: A phone app... no, not a calculator to multiply by 60, but to use as a tachometer with the microphone, there are a few and they work reasonable, you configure the typo of motor, #cylinders, strokes, it does the rest.JS
Small epaper display & query - Page 1
Forum section: electronics / beginners

author: embedded.world@aol.com
author_rank: Contributor
timestamp: May 27, 2014, 11:00:02 am
content: Does anyone know where I can get small e-paper display (sunlight readable).I searched for smaller display like: 1.44" likehttp://www.pervasivedisplays.com/products/144but I want to go smaller like 0.96" or 1".1. How to view e-paper in night. Do they have LED on back.

author: josem
author_rank: Regular Contributor
timestamp: May 27, 2014, 11:27:11 am
content: I don't know any e-paper display that small, but try contacting this company maybe they do make them:http://goodlcd.en.alibaba.comThat said a big advantage with Pervasive Displays is they're very well documented and have example code of how to drive them in their RePaper project.E-paper displays have to be frontlit, as they don't let light through from the back. See Dave's EEVblog episode #370 - Kindle Paperwhite Teardown - to understand how a frontlight for these displays works.If you don't mind using a tiny amount of power (10 uW) to keep the display running another option I would recommend are Sharp's Memory Displays. These come as small as 0.99" and are very easy to drive as well needing very low power (although not 0 in the standby state as e-paper does) These can be frontlit or backlit.

author: Neganur
author_rank: Unknown
timestamp: May 27, 2014, 11:35:06 am
content: what quantity are you talking about and does the display have to be dot matrix or do you need it custom made with segments?
Small footprint high-side shift register equivalent - Page 1
Forum section: electronics / beginners

author: Rasmo
author_rank: Contributor
timestamp: November 20, 2024, 08:57:48 am
content: Hi all,I am trying to find a small footprint solution to logically switch on / off some pull-up resistors. I need 8x 5V outputs that will source about 1-2mA, but I don't have a lot of pins left on my micro. A 74HC595 would work, apart from the fact that the outputs will end up sinking current when 'off' which isn't ideal. Is there any components that I am missing that would provide this functionality in a small footprint? I'm trying to avoid having both a shift register and additional transistors. Failing that, what would be the smallest way to get 8x high side outputs (PNP, FET, driver etc.).There are a lot of parts for driving LEDs from a serial input (I2C etc) but most of those seem to be low-side.Thanks,Michael

author: Terry Bites
author_rank: Super Contributor
timestamp: November 21, 2024, 08:08:04 am
content: Change the input logicical "true" to 0 in code?

author: nali
author_rank: Frequent Contributor
timestamp: November 21, 2024, 08:21:44 am
content: Quote from: Terry Bites on November 21, 2024, 08:08:04 amDoesn't help this:QuoteMIC5891may do, might be a bit OTT though?

author: ftg
author_rank: Frequent Contributor
timestamp: November 21, 2024, 01:05:32 pm
content: There are also high side switch chips from many folks.Some with GPIO control and some with SPI or I2C control.Would 8x really small P-fets or PNP "digital transistors" with integrated resistors be an option?

author: Ian.M
author_rank: Super Contributor
timestamp: November 21, 2024, 03:57:25 pm
content: Maybe put Schottky diodes in series with the 74HC595 outputs?BAT40Vgets you two in only 3 mm2of board area.

author: Rasmo
author_rank: Contributor
timestamp: November 23, 2024, 12:36:11 am
content: Thanks, I think I will probably have to do it with 2 layers (IO expansion (HC595 or similar) then either diodes or transistors) as you are suggesting. Was just checking there wasn't something simple out there that I hadn't heard of before that would do both.