hybridfree/eevblog-posts huggingface dataset:
Optically isolated channels for SPI - Page 1
Forum section: electronics / projects

author: Omar
author_rank: Newbie
timestamp: September 01, 2022, 08:33:41 pm
content: Hi 😊I'm currently working on graduation project that includes battery management system and it will be 48 v....So 13 lithium Ion cells will be connected in series...And i have to monitor every individual cell voltage and temperature 😭😭...I would go with mcp3008 ADC to do that task ....But the problem is that every ic will monitor 4 cells and it will be at higher voltage above the main processor...I mean that zero volt and 5 v of digital signals will be higher than the main processor by 20 and 36 v ....I have an idea of creating 4 optically isolated channels for SPI communication protocol.........The question is ...Is that possible???Did you see something like that before???Is there a better solution???

author: David Hess
author_rank: Super Contributor
timestamp: September 01, 2022, 09:10:58 pm
content: SPI is one of the easier interfaces to optically isolate because all of the signals are one way with clock output, data output, data input, and select if needed. And since logic level signals are used, the same circuits used to isolate logic level signals can be used with SPI.Vishay suggestsusing logic level optocouplers but any transistor optocoupler can be used as well.

author: MasterT
author_rank: Frequent Contributor
timestamp: September 01, 2022, 09:34:02 pm
content: Not necessarily "optical" - galvanic isolator , or digital isolator. There are many,https://www.mouser.ca/c/semiconductors/interface-ics/digital-isolators/Or you can use Isolated ADChttps://www.mouser.ca/c/semiconductors/data-converter-ics/data-acquisition-adcs-dacs-specialized/?product=Isolated%20Analog%20to%20Digital%20Converters

author: Benta
author_rank: Super Contributor
timestamp: September 01, 2022, 09:41:36 pm
content: Look at the TI series of ISO7xxx digital isolator IC's. Cheaper and easier.This one's made for SPI:https://www.ti.com/product/ISO7041

author: ajb
author_rank: Super Contributor
timestamp: September 02, 2022, 03:44:47 pm
content: Thirding the digital isolator suggestions, they're a much better solution than actual optos for applications like this. They're available in varying channel count/direction combinations, so it's pretty easy to get a single part that will isolate all of the channels you need in the correct directions for most common applications.
Optically-treated glass in front of vidicon/trinicon - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 03, 2018, 01:41:29 pm
content: My brother brought me a Sony Trinicon tube from an old camcorder. What is the purpose of the tinted glass in front of the tube?It doesn't block IR, so I guess it blocks UV? Looking through it just makes things a bit darker and I think it makes yellows "pop" a bit more and mutes the rest of the colors.

author: coppercone2
author_rank: Super Contributor
timestamp: September 04, 2018, 01:54:37 am
content: Maybe they have a filter that negates the quantum efficency irregularities?

author: m98
author_rank: Frequent Contributor
timestamp: September 06, 2018, 10:43:22 am
content: Maybe X-ray shielding?

author: RobK_NL
author_rank: Frequent Contributor
timestamp: September 06, 2018, 11:25:23 am
content: https://en.wikipedia.org/wiki/Video_camera_tube#Trinicon
Optimal Rechargeable or Secondary Battery Charging - Page 1
Forum section: electronics / projects

author: saturation
author_rank: Super Contributor
timestamp: May 24, 2010, 06:02:46 pm
content: There are at least 3 major methods to recharge secondary batteries, and variations of these:Constant current, or galvanostaticPulse chargingBurp or Reflex charginghttp://corsair.flugmodellbau.de/files/elektron/NASA-II.PDFI have always taken it for granted that its known which is better, but its seems the optimal charging scheme isn't settled. If you built your own, how did you determine the frequency and pulse widths in both positive and discharge curves, if you use reflex. Among pulse chargers I've sampled the pulse widths, and frequency all vary.http://www.powerdesignersusa.com/pdf/Tech%20Brief%20Negative%20Pulse%20Charging%20Techniques%20Myths%20&%20Facts%20-%20Final.pdfI am looking for experiences with charging methods readers find optimal and which charger you use. Most commercial chargers are either constant current or pulse.http://www.batterylifeplus.com/images/PDFs/Nguyen_2003.pdfThe few that support reflex charging are often costly, in the $300-400 range.http://www.amainhobbies.com/product_info.php/products_id/145655/n/Bantam-E-Station-BC8DP-NiCad-NiMH-LiIo-LiPo-LiFe-Pb-AC-DC-Balancing-Chargerhttp://www.westbourne-model.co.uk/fusion-l702b-pro-emperor-dc-charger-10306-0.htmlIs the extra expense worth it for reflex charging?More on charging methods:http://www.mpoweruk.com/chargers.htm#pulse

author: TheWelly888
author_rank: Frequent Contributor
timestamp: May 24, 2010, 06:55:23 pm
content: An important reason to choose the charging method is the chemistry of the rechargable battery.Lead acid batteries need constant voltage charging, Nickel Cadmium and Nickel Metal Hydride need constant current charging ( and that these currents MUST be reduced as soon as the batteries reach full voltage )Lithium Ion batteries - I can't remember off hand if it is CV or CI charging but great care must be taken to avoid overcharging or deep discharging as permanent damage will be caused in either case.Here is another useful websitehttp://www.batteryuniversity.com/
Optimal way to mount 3 ultrasonic transducer onto a stainless steel tray - Page 1
Forum section: electronics / projects

author: Shay
author_rank: Regular Contributor
timestamp: April 20, 2024, 04:24:19 pm
content: Hello,I'm seeking guidance on the optimal method for mounting ultrasonic transducers to minimize potential issues related to interference or standing waves.I have three 40W 40kHz ultrasonic transducers, typically utilized for ultrasonic cleaners.Given that the tray is approximately 20cm x 20cm x 20cm (equivalent to 8 liters, with a recommended power of 10W per 1 liters), I am contemplating mounting three of the 40W transducers, each running at about 35W RMS, to enhance longevity and reliability.One approach involves arranging them in a row beneath the tray. Alternatively, a triangular configuration could be employed. Another option is to mount one on the bottom, one on the right wall, and one on the left wall.I am uncertain which placement would be most optimal for these transducers. The cleaner will primarily be utilized for cleaning PCBs.Thank you.

author: ch_scr
author_rank: Frequent Contributor
timestamp: April 21, 2024, 06:37:43 am
content: From my understanding, there will always be standing waves. One can either sweep the frequency to make them move, or move the item to be cleaned. The energy distribution can be visualized by sonicating a piece of Al foil in the water bath. One would want an "about equal" distribution of the holes pierced into the foil. But AFAIK, there will always be some kind of "main lobe".

author: moffy
author_rank: Super Contributor
timestamp: April 22, 2024, 05:59:38 am
content: I might try the three inline but if they are externally driven you can always play with the phase between the transducers to play with the interference patterns maybe even modulate the phasing, something to experiment with.
Optimizing QFN64 Paste layer for diy stencil - Page 1
Forum section: electronics / projects

author: Spikee
author_rank: Frequent Contributor
timestamp: November 13, 2014, 10:30:50 pm
content: So I have been using my Silhouette cameo (230 euro) to cut my own smt stencils with BG-40.5 RS transparency paper and it works awesome.Now I have an MCU with QFN64 pinout and while my machine can cut the pads perfectly you still have to press the cutted parts out of the transparancy sheet because they are so small they still are stuck a little. On bigger parts this is not an issue, but the qfn is 0.5mm pitch and the bad is 0.2mm x 0.75mm which makes that really hard when using a tweezer to push it out.I tried dispensing the solder paste via an syringe but that also kinda sux.Now I was thinking make the past expansion of the qfn part just a line so it is easy to push out and there wont be to much solder paste on the pads.But how wide should I make the "line" ?The qfn pad width is 0.2mmpicture:the yellow line is supposed to be the new solder paste expansion pad (now 0.1mm wide)Does anyone have experience with this , is there like a rule of thumb?

author: sleemanj
author_rank: Super Contributor
timestamp: November 14, 2014, 01:47:10 am
content: Quote from: Spikee on November 13, 2014, 10:30:50 pmCan't help you with the expansion, but have you tried just sticking some low-tack tape over the problem areas and pulling it off, maybe it will be enough to pull out the stuck bits.NB: I assume you're using the gerber2graphtec etc developed in this threadhttp://dangerousprototypes.com/forum/viewtopic.php?f=68&t=5341

author: Spikee
author_rank: Frequent Contributor
timestamp: November 14, 2014, 10:39:46 am
content: yes i'm using that program. I have not yet tried using tape or other adhevesives to get it of.But still I would like to try and get some info about the amount of solderpaste needed in an line.

author: zapta
author_rank: Super Contributor
timestamp: November 14, 2014, 01:26:49 pm
content: I would make it to have the same area as the total area of the pads. This way you will have the same amount of solder paste.
Optimizing triac "dimmer" filtering for high power resistive loads 2-4kW  - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: April 11, 2024, 10:27:34 am
content: Hi folks,are there any general recommendations when selecting filtering for phase control with big resistive loads?The target loads are 2kW 230V heating elements.As they are powered by solar inverters in off-grid mode, there are also some concerns about the effects on the inverter in the worst case of 50% duty.Should I slam there the bigger choke it can hold and call it a day or are there better approaches?

author: Zero999
author_rank: Super Contributor
timestamp: April 11, 2024, 10:45:57 am
content: Don't use phase control. Use PWM, with zero crossing, also known as burst control, instead.

author: Miyuki
author_rank: Frequent Contributor
timestamp: April 11, 2024, 04:55:54 pm
content: I can probably switch to single cycle step burst. That is a reasonable solution.

author: strawberry
author_rank: Super Contributor
timestamp: April 11, 2024, 07:34:27 pm
content: its more efficient when heating element is directly connected to solar battery (in case battery is close to 230V)no filters no zero crossing no burden for DC/AC PSU

author: Miyuki
author_rank: Frequent Contributor
timestamp: April 11, 2024, 07:58:43 pm
content: It uses a 60V battery and has grid power as a backupAlso, the inverter efficiency ranges from 92% to 95% depending on the load. That is a relatively small loss.But it probably can swap one of the heating elements to the 60V version and use a PWM drive with a big mosfet. But this still shall have some filter. And need to have separate thick wiring.

author: strawberry
author_rank: Super Contributor
timestamp: April 11, 2024, 08:46:52 pm
content: 2Hz PWM with slower edgestriac seems ~1-2% lossit will be fun to watch how energy company try to figure-out why energymeter is pushing and pulling from grid 2x per sec

author: johansen
author_rank: Super Contributor
timestamp: April 11, 2024, 10:16:17 pm
content: Lots of people blow up mosfets in diy battery dump loads, because they don't seem to understand the supply inductance problem; when the switch turns off, the current keeps flowing until the energy is dissipated--into the mosfet.You don't need filtering after the switch, its just a pwm buck converter. its the loop formed by the supply side capacitor, mosfet, and flyback diode that needs to be small, and the mosfet(s) may need an RC snubber for noise.

author: richard.cs
author_rank: Super Contributor
timestamp: April 12, 2024, 08:41:53 am
content: Quote from: strawberry on April 11, 2024, 08:46:52 pmKeep it under 1 Wh (3600 J) and the meter won't record it - a dead band like that is in most meter specifications as an anti creep feature. It corresponds to one turn of the disc in most styles of mechanical meter.
Optional pull-up resistors for I2C driven by single GPIO - Page 1
Forum section: electronics / projects

author: bootsector
author_rank: Newbie
timestamp: March 18, 2018, 11:40:50 am
content: Hi there!I'm planning to add an optional pair of pull-up resistors for I2C communication (PB10 and PB11) driven by a GPIO (PB7) from a micro-controller:The idea is to keep PB7 in input-floating mode until I'm about to use PB10 and PB11 for I2C. In that case, PB7 will be put in output-high mode, activating the pull-ups.My question is: would leaving PB7 in input-floating mode really make like the pull-ups weren't part of the circuit? PB10 and PB11 will be re-purposed for other type of communication that doesn't require pull-ups, so I don't want them interfering with the circuit in that case.What do you guys think?Cheers!PS: PB7 is the only GPIO pin I have left, there's no other available.
Options available for AC to DC power supplies. - Page 1
Forum section: electronics / projects

author: Krumm
author_rank: Contributor
timestamp: February 29, 2016, 04:46:32 am
content: I'm currently putting together a small project based on the Arduino (so 5VDC and able to supply approx 250mA) and I'm looking to power it from mains (240VAC) using screw terminals as the connectors, as the project switches mains voltage anyways. The main requirements I have is that it must be a regulated isolated power supply, should be reasonably cheap and shouldn't be a terrible quality one that would get ripped a new one by Dave!... I'm well aware that I can only really pick two of those requirements but let's see how close I can get!My thinking has been to get an external adapter such as the one below and simply connect wires from the screw terminals and solder them to the plug. This has the advantage of at least easily separating the mains from the low power side of the project. The issue I have with these power supplies is that they are the sort of power supplies that 99% of the time their QC is terrible and are often dangerous. But one advantage is that it (assumingly) has all the circuitry inside that is needed and I get a reasonably good DC supply out. That particular one is only £3.60 (around $5), but can I count on the fact that it is from somewhere like Farnell that it is of a good build quality? Also, that particular one has got a ripple of 200mV p-p at 20MHz, I'm not sure if that means it is up to much!http://uk.farnell.com/2451869Another method which seems more suitable is something such as a PCB mounted converter. It would appear from the datasheet that once again all circuitry is enclosed within the package, there is no mention of ripple, so I would have to contact the manufacturer I imagine. They are a little more expensive at just under $10 but there doesn't seem to be a great deal of information on the net of people using these in projects which makes me a little bit more leery of them.http://uk.farnell.com/1825779What suggestions are there for 'in project box' power supplies?Thanks!

author: Ian.M
author_rank: Super Contributor
timestamp: February 29, 2016, 06:50:03 am
content: Try googling: 5V inline psuThis looked particularly promising:http://cpc.farnell.com/1/1/86189-stontronics-t4456st-inline-power-supply-12v-1a-2-1mm.htmlThe major advantage is its easy to mount and wire up with no live connections exposed.Buying from Farnell is no guarantee that the build quality is good, but it will at least be 'as described' and meet the relevant EU safety standards.
Options for radio frequency (HF) low pass filter capacitors - Page 1
Forum section: electronics / projects

author: Chris-U239
author_rank: Newbie
timestamp: October 04, 2020, 01:10:45 am
content: I shortly need to build some low power transmitters operating around 3.7mhz at a power level of 50w. I have built higher power amplifiers many times, where cost of capacitors is not so much of a percentage of total cost. For these units I use ATC Caps (American Technical Ceramics) and never had any problems.For the smaller transmitters I would like to use disc ceramics, due to cost restrictions but I have can`t find any type of disc ceramic that does not heat up. I have seen disc ceramics used in commercial amplifiers of this power level, but these must be a kind that I don`t know about. I am aware that silver mica would be a good option, but these are also cost prohibitive.The capacitors are to be used in a Chebyshev low pass filter 7 element, inductor input, 50 ohm, unbalanced.Any advice would be greatly appreciated,Chris.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 04, 2020, 02:19:27 am
content: What values?If you "can't afford" C0G ceramics it's a hopeless pursuit.I don't know of any current application of SM caps that isn't easily substituted or simply better with ceramics. As far as I know they only exist for maintenance of old designs (probably with a heavy emphasis on military customers?).Don't poo-poo SMT chip components. They're often easier to use, and definitely perform better.Tim

author: bob91343
author_rank: Super Contributor
timestamp: October 04, 2020, 05:11:35 am
content: Disc ceramic capacitors have a flaky reputation if you expect them to carry significant current. What happens is the very thin conductive layer gets warm and vaporizes so its capacitance drops.Perhaps a better candidate is old fashioned molded mica. The frequency isn't so high; 80 meters is not much above audio actually. Perhaps a few tubular capacitors will do.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 04, 2020, 05:45:30 am
content: For that matter, polypropylene should be fine as well. High current, low loss, snubber or peak rated types. You just might not have as much choice of small or precise values.Another point in favor of SMT chip: least ESL for best stopband attenuation. ESL puts a zero at some higher frequency, might be 10s of MHz, might be 100s, depends, who knows. Might not matter much for a class AB or C amplifier, or might be a good idea for class D.Tim
options for sub 1ghz transceivers - Page 1
Forum section: electronics / projects

author: KTP
author_rank: Frequent Contributor
timestamp: June 18, 2012, 03:41:18 am
content: I need a cheap short range transceiver to work with an ATXMEGA32 microcontroller. What do you guys who play with this type of stuff use? I have some of the TI RF2500 modules but I need minimum latency on several IP cams operating in that frequency range and was thinking of sub ghz for these transceivers. The range is very short (maybe 10m maximum, line of sight) but there will be up to 16 of these operating at the same time.Anything you guys have had experience with that you like? Modules that get me up and running fast are a bonus.The 915mhz microchip module for $10 looks interestinghttp://ww1.microchip.com/downloads/en/DeviceDoc/75017A.pdfThanks.

author: T4P
author_rank: Super Contributor
timestamp: June 18, 2012, 06:09:19 am
content: http://www.aliexpress.com/product-fm/555949596-RF-2400-NANO-12x12mm-NANO-Size-2-4G-RF-Module-Wireless-Transceiver-Module-wholesalers.html

author: steve_w
author_rank: Regular Contributor
timestamp: June 18, 2012, 08:13:02 am
content: What county do you want to use it in, not every country allows video bandwidth transmissions in sub 1 Ghz band. If its low power and you dont cause interference with mobile phones you will probably be OK.regardsSteve w

author: KTP
author_rank: Frequent Contributor
timestamp: June 18, 2012, 11:39:01 am
content: Quote from: steve_w on June 18, 2012, 08:13:02 amNo, sorry, I think it was not clear what I intend. I am using this in the USA. The video transmissions are being done on 2.4Ghz so to avoid any possibility of interference I was thinking of doing the other telemetry with 915mhz.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 18, 2012, 11:51:18 am
content: TI CC1100 - fairly compatible with the 2.5g chips.

author: deephaven
author_rank: Frequent Contributor
timestamp: June 18, 2012, 11:56:01 am
content: I've used thesehttp://www.lprs.co.uk/easyradio.html
Opto-Isolated Cabling - Page 1
Forum section: electronics / projects

author: rockbassist90
author_rank: Contributor
timestamp: June 17, 2014, 02:23:01 am
content: Designing controls for a HV environment....making a PCB with opto isolation to RJ-11....on my other end is a DB9 male required...any recommendations for industry (reliable) optically isolated cabling? First time designing in for this type of environment.Thanks in advance.

author: Rerouter
author_rank: Super Contributor
timestamp: June 17, 2014, 03:17:11 am
content: to clarify the cable is running along side high voltage wiring, or the board is operating at a higher voltage than what the connector is at, as each required a different approach,equally what voltage levels, 2KV is much easier than 33KV,as a starting though if the board is at a higher potential, figure out your direction and simply use opto-couplers with a pullup provided by whatever it connects to,if it has to run along side some very high voltages and you cannot find wiring with high enough insulation you can use toslink optic fiber to create a completly optical path to the connector, once again it would need power on the other side for the photo-transistors,
Opto isolated Flyback with opto in Common Collector, or Common emitter? - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: December 26, 2017, 05:09:10 pm
content: Hello,The attached show 5W, Opto-isolated Offline Flyback SMPS’s.One has the feedback opto connected in common collector, one in common emitter. Which do you believe is best?For the controller in each case, please assume it is the UCC28C43…(not the LT1243)UCC28C43 datasheet.http://www.ti.com/lit/ds/symlink/ucc28c43.pdfLTspice sim of them attached, ..also schem
Opto isolator crossreference? - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: August 02, 2018, 09:21:52 pm
content: Need to replace Sharp PC3Q67Q quad-pack (16-pin SOIC). This part is obsolete:http://www.allxref.com/pdf/sharp/pc3q67q.pdfI've searched for an on-line cross-reference to find an equivalent. No joy. (Any pin-count will do: only one quadrant of this package is dead; I could piggy-back--dead-bug-style--a 4-pin pack if needed.)The unique(?) think about this part is the input LED has a If of 50mA-1A. I don't recall seeing that high a current for LEDs, although I'm no design engineer...Any help would be greatly appreciated.Thanks.

author: Paul Price
author_rank: Super Contributor
timestamp: August 04, 2018, 01:21:09 am
content: Looks like you are misreading the spec. sheet. You are assuming that absolute max values would be used in normal operation.The LED input currents in common use would be 5-15mA, depending on the output current and voltages being controlled. The higher the current in the output, the higher the current required for the LED, butlow power dissipation limits do not allowconditons where sustained high currents are applied to the LED input or allowed to flow in the transistor output.What's neat is the the pinout of the chip is such that it would alow you to just lay a single 4-pin optocouplers over the existing bad opto and cutting the old ic's pins.Think FOD817 type optocoupler.
Opto Triac circuit versus SSR - Page 1
Forum section: electronics / projects

author: hobbyelectronics
author_rank: Regular Contributor
timestamp: March 07, 2024, 09:53:57 pm
content: Hi,I am looking at using a TRIAC circuit to drive a 230 VAC load. I understand how to drive a TRIAC using an opto-coupler.I have the need to drive the load using phase control or possibly some sort of burst control to allow the power to the load to be varied. This will be based around a small ARM M0+ micro, with zero crossing detection so I can fire the TRIAC or turn on the SSR at the right time.The only question I have, is apart from cost why would I use discrete components for this instead of just using a SSR (Non ZCD)?Many SSRs are basically a TRIAC based circuit with opto-coupling, filtering and snubber etc built into one unit.Looking at switching speeds etc and other specs, it would seem many SSR's would be perfect for this.Is this just down to cost, or perhaps their are other reasons why or why not to use an SSR. Or have I got this totally wrong and missing something here.Some small SSR's for a relatively low power AC load seem fairly low cost.ThanksPaul

author: moffy
author_rank: Super Contributor
timestamp: March 07, 2024, 10:11:07 pm
content: The advantage of the SSR is that it is a black box with a specification that all you need to use is abide by the spec and provide a suitable input. You don't need to know about triacs or mosfets or heatsinks etc., but you pay for the privilege, and if you need something non standard then you are stuck. Knowing about triacs you are free to roll your own or not.

author: hobbyelectronics
author_rank: Regular Contributor
timestamp: March 07, 2024, 10:25:43 pm
content: Yes, that's how I understand it.Seems that for my case using a small SSR would be ideal.Saves some PCB space as well and assembly time / cost instead of discrete components.Thanks
Optocoupler and triac connection question - Page 1
Forum section: electronics / projects

author: Asim
author_rank: Regular Contributor
timestamp: October 02, 2013, 08:03:43 pm
content: Hi guys,I am using a microcontroller to control an AC motor with 700 Watts.my question is: what should be the power ratings for R1 in this schematic?http://dev.emcelettronica.com/files/node_images/untitled_0.jpgThanks.

author: Harvs
author_rank: Super Contributor
timestamp: October 03, 2013, 12:19:45 am
content: R1 only conducts at the turn-on of the main triac, and because you're using a zero-crossing triac driver it will be only at the start of the mains half cycle when the voltage is low. Therefore there's very little power dissipated in that resistor. I typically use a 1/2W, though you could probably get away with a 1/4W.

author: Psi
author_rank: Super Contributor
timestamp: October 03, 2013, 02:50:39 am
content: Also, you need a resistor on the input section so the LEDs don't blow.

author: Asim
author_rank: Regular Contributor
timestamp: October 03, 2013, 03:57:59 am
content: Alright , thanks Harves.Psi, i have put a resister on the input , thanks
Optocoupler LED Lifespan vs Current - Page 1
Forum section: electronics / projects

author: Pentoad
author_rank: Regular Contributor
timestamp: May 21, 2020, 08:07:39 pm
content: I am using an EL357N optoisolator in a project and I am supplying it 5v through a 500 ohm resistor. It draws 7 milliamps. The absolute maximum rating for it is 50 milliamps. Do you think I am overdriving it and would it be better to lower the current? I understand this could affect the CTR but the output phototransistor is only driving the gate of a small mosfet at frequencies well below 1 hertz.

author: thm_w
author_rank: Super Contributor
timestamp: May 21, 2020, 09:11:49 pm
content: 8mA is fine.The absolute maximum rating is 50mA, and the "typical" rating is 20mA, which it should last many years on.Keep in mind the spec and forward voltage change at various temperatures, CTR range, etc. But in your case 8mA has tons of headroom.http://www.everlight.com/file/ProductFile/EL357N-G.pdf
Optocoupler Manufacturer and Datasheet Needed! - Page 1
Forum section: electronics / projects

author: EdBud
author_rank: Newbie
timestamp: January 09, 2023, 02:22:24 pm
content: Hello, I am reverser engineering a 1980's circuit card that uses an optocoupler that I am unable to identify the manufacturer by Logo or part number. The part number is "030P11". The logo is a circle with some internal lines as shown in the attached photo. The case is a: four-lead, metal can, type TO-72. Any information would be greatly appreciated.

author: gamalot
author_rank: Super Contributor
timestamp: January 09, 2023, 03:58:34 pm
content: The only clue I can find is the logo, which used to belong to Optek (now TT Electronics I think).

author: Doctorandus_P
author_rank: Super Contributor
timestamp: January 09, 2023, 04:28:41 pm
content: Why do you think it is an optocoupler?It is very uncommon for optocouplers to have a metal case.But if it's an optocoupler, one side will have an IR diode with a voltage drop of around 1V, and the other side usually has a phototransistor.And it's in a circuit it's also easy to figure out what the connections and drive currents are.

author: bidrohini
author_rank: Regular Contributor
timestamp: January 10, 2023, 11:36:45 am
content: Is that really an optocoupler? The symbol on its body is different from that of an optocoupler.

author: gamalot
author_rank: Super Contributor
timestamp: January 10, 2023, 12:28:09 pm
content: Quote from: bidrohini on January 10, 2023, 11:36:45 amIt is not a symbol, it's manufacturer's logo.https://pdf1.alldatasheet.com/datasheet-pdf/view/87837/OPTEK/3C92C.html

author: niconiconi
author_rank: Frequent Contributor
timestamp: January 12, 2023, 07:09:00 pm
content: Quote from: Doctorandus_P on January 09, 2023, 04:28:41 pmThat's the point. Optek (now purchased by TT Electronics) makes some of the most specialized optocouplers in the industry, including high-rel types. I think their customer is the military-industrial complex. Their high-voltage types are also really interesting, with a creepage distance ranges from 20 mm to 80 mm! They're basically sealed LED, fiber optics, and phototransistor in epoxy packages. I just needed one of these in a high-voltage project.Take a look at their product catalog, you would be impressed.

author: EdBud
author_rank: Newbie
timestamp: January 17, 2023, 01:04:18 pm
content: Good morning All,Thanks to all who provided responses to my inquiry. Yes, the component is indeed an optocoupler and due to its military application, it does (or did), come packaged in a TO-72 metal can with four leads. Unfortunately, OPTEK is not the manufacturer. I originally thought the logo was OPTEK and I reached out to their engineering team for assistance. The 030P11 part number is not listed in any of their archived databases. In addition, OPTEK part numbers have never begun with a leading zero. Still searching for a datasheet or manufacturer.
Optocoupler question - Page 1
Forum section: electronics / projects

author: otter
author_rank: Newbie
timestamp: June 18, 2020, 09:47:13 am
content: How do I read out the Vce from the datasheet below, if I use If=8mA and Ic=120mA?https://www.onsemi.com/pub/Collateral/MOCD223M-D.PDF

author: magic
author_rank: Super Contributor
timestamp: June 18, 2020, 09:57:30 am
content: You can't. Current transfer ratio is only 500% guaranteed and 1000% typical, which means 5x or 10x more Ic than If.See figure 4. With If=10mA you only get a few times more Ic than with If=1mA, which would be 10mA typical. You could increase collector current by applying even more than 5Vwhile the optocoupler is turned onbut come on.

author: moffy
author_rank: Super Contributor
timestamp: June 18, 2020, 09:58:11 am
content: The current transfer ratio is min:= 5x, typ:= 10x with Vce = 5v. Therefore with If = 8ma, the CTR falls off a bit so lets say about 35ma is the maximum output current you could rely on at 25C.

author: Ian.M
author_rank: Super Contributor
timestamp: June 18, 2020, 10:21:44 am
content: Its worse than that as the O.P's linked datasheet doesn't include any operating lifespan or reliability data. As LED light output is well known*to degrade over the LED's operating life, it would be foolish to design with less than a factor of two margin, i.e. about 17mA Ic, if you want it to have a reasonable chance of reaching 10000 operating hours without failure. If its on all the time 10000 hours is barely enough to outlast a one year warranty!* e.g.https://www.vishay.com/doc?49267

author: otter
author_rank: Newbie
timestamp: June 18, 2020, 11:00:47 am
content: If I use the this part instead (new link below), it seems I can get 120-140mA with Vce=1V with If=5mA.What can be expected if I increase If to 10mA?Do I need the selection "K" to get this results?I will consider deratig.https://www.mouser.se/datasheet/2/698/PN10235EJ04V0DS-1528581.pdf

author: magic
author_rank: Super Contributor
timestamp: June 18, 2020, 11:05:13 am
content: Use the optocoupler to drive some 2N2222 if possible. They aren't really meant to control high current by themselves.Alternatively, some kind of opto-mos, solid state realy, that kind of stuff.
optocoupler - zero voltage detect - usage question - Page 1
Forum section: electronics / projects

author: localbroadcast
author_rank: Contributor
timestamp: June 13, 2016, 10:41:41 am
content: Hello! I am thinking of using the optocoupler with part number moc3062 in combination with a microcontroller (arduino) to control a mains voltage device. (120vac 60hz where Im from). It would most likely be an inductive load such as a motor or a heater coil, so phase angle chopping of the mains sine wave is the goal here.So.. basically I've had a look at the datasheet of this optocoupler, and I'm having trouble understanding basically how you would use this thing! I get that you are supposed to use a triac or similar in combination with this, but where do you connect your microcontroller input, and what would you have to input in order to achieve the control I'm after? like... where is the output on this thing that tells the microcontroller that you've hit the zero voltage crossing mark?? How would your microcontroller tell this thing that you wanna wait 75 degrees of the sine wave after the zero crossing before turning back on, or 80 degrees of the sine wave, or whatever the microcontroller wants to set the thing at?? I'm sure more than a few people can fill me in here... Thanks!

author: Ian.M
author_rank: Super Contributor
timestamp: June 13, 2016, 11:07:15 am
content: You've got it ass-backwards. You are looking for something that detects zero crossings on the input side and transfers them to an optoisolated output. However the MOC306x parts are designed for On/Off applications where proportional (phase angle) control is not required. They detect zero crossings on the output side so that they will delay firing the external TRIAC until the beginning of the next half cycle, when there is minimum voltage accross it, minimising EMI and current surges. There is no way to use one and get an opto-isolated zero crossing pulse out.

author: Zero999
author_rank: Super Contributor
timestamp: June 13, 2016, 11:40:12 am
content: You need an opto-coupler with a bidirectional LED on the input, such as the IL255 or IL755. Connect the LED to the mains via a suitable current limiting resistor. When the current through the input LED falls to zero, the phototransistor will turn off, indicating the mains voltage is near zero.The TRIAC can then be triggered using a TRIAC opto-coupler, without the zero crossing, such as the MOC3020.http://www.ti.com/lit/ds/symlink/moc3022.pdfhttp://www.vishay.com/docs/83641/il755.pdf

author: retrolefty
author_rank: Super Contributor
timestamp: June 13, 2016, 11:55:32 am
content: Your best off just using a proper commercial AC SSR module. It can wired directly to a 5 volt digital output pin and will be optically coupled from the AC side. They come in two styles, internal zero-crossing type (most common) and 'phase controlled' type. To use a phase controlled type you will also have to have an external zero crossing detection circuit/device to allow your MC to effectively PWM the AC load side.
optocouplers ( doubling Vce?) - Page 1
Forum section: electronics / projects

author: Scutarius
author_rank: Regular Contributor
timestamp: July 06, 2010, 04:52:00 pm
content: Hi, I want to use some optos that I have for a 100Hz application but I need a 100VceSo, if have these optos with a Vce of 70v, that just work fine with my application (why?) can I put 2 in series to be sure that will survive the stress for a long time?thank you

author: Zero999
author_rank: Super Contributor
timestamp: July 06, 2010, 05:46:10 pm
content: No, you can't put two in series and expect it to be fine because you can't guarantee that they'll both switch on at exactly the same time.

author: Scutarius
author_rank: Regular Contributor
timestamp: July 06, 2010, 05:55:56 pm
content: do you mean that I can not say that if I put in parallel the As and Ks of the LEDs and in series the E and C of the transistors I wouldnt get the same response?thank you

author: Time
author_rank: Frequent Contributor
timestamp: July 06, 2010, 07:31:22 pm
content: Why not just use the output side of the of the opto couplers to drive something more robust that can handle the 100VQuote from: ee.jcesar on July 06, 2010, 05:55:56 pm

author: Zero999
author_rank: Super Contributor
timestamp: July 06, 2010, 08:32:01 pm
content: Quote from: ee.jcesar on July 06, 2010, 05:55:56 pmSuppose one transistor turns on before the other?You'll have one 70V transistor with 100V across it. It might survive for a short length of time but it might fail in the long term.Anyway, you shouldn't put the LEDs in parallel, they should be in series.

author: Scutarius
author_rank: Regular Contributor
timestamp: July 06, 2010, 08:56:42 pm
content: thank you, I will try another opto then.

author: Time
author_rank: Frequent Contributor
timestamp: July 06, 2010, 10:31:21 pm
content: I worked on something similar with 2 optocouplers in series on the LED side. The optocouplers worked in parallel on the (push-pull in the case of FOD3180 I think it was) output to provide gate current for 2 SCRs rated at 1.5 kV with a total voltage of 2 kV across them both. The jitter caused by the 2 optocouplers was enough to cause the SCRs to have a very short lifetime. Since they could not be triggered at precisely the same time the over voltaging took its toll.The company who made the SCRs stopped making them but the device was still being used readily in the lab - of course this was bad! Soooo... my boss told me to build something better to replace.
optoisolator aging  - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 28, 2015, 03:02:18 am
content: I understand these age and the CTR changes. Do they age when in storage, or only when they run/get hot?Before I start the repair of a 25 year old CRT monitor, I wanna know if I should look there first.

author: moffy
author_rank: Super Contributor
timestamp: April 28, 2015, 03:07:50 am
content: They don't tend to degrade much in storage unless it is very very hot.
Optris CTLT IR Sensor ASCII Mode - Page 1
Forum section: electronics / projects

author: nick.trim
author_rank: Newbie
timestamp: July 06, 2016, 12:50:12 pm
content: Hi Guys,Bit of a long shot but have spent an entire day trying to switch this thing from Binary more to ASCII so that i can interface if with my Micrologix PLC. Hoping someone here might have used them before.OPTRIS CT LThttp://www.optris.com/optris-ct-lt?file=tl_files/downloads/Manuals/Englisch/Compact%20Series/Manual%20optris%20CT.pdfNormally, the module communicates with a binary protocol. I have changed the head code as shown in the manual and have tried the special command to change the protocol writing "Decimal: 131" or "HEX: 0x83". The answer should be 1 Byte with "0 = binary protocol" or "1 = ASCII protocol". I am talking to the device over an USB-RS485 adapter and can read the temperature information in Realterm by entering and sending (178 1) 178 = B2 which is the multi drop addr and 1 which returns the target temperature in binaryI have tried all sorts of things through realterm to send the the 131/0x83 code to the device to change it to ASCII but don't see a response, or a change that would indicate it has switched over to ASCII (?TCR is what i tested, with and without the CR etc.) Bashing my head against the wall, hoping someone has as suggestions what i might be doing wrong?Have tried to follow the instructions to the letter as outlined herehttp://www.optris.com/interfaces?file=tl_files/downloads/Manuals/addendums-de-en/ct-ctlaser-commands.pdfHELP!
Orange Pi Zero not booting completely  - Page 1
Forum section: electronics / projects

author: Swaroop 21
author_rank: Regular Contributor
timestamp: July 20, 2024, 06:38:15 am
content: I have tried many Images on (Orange Pi Zero LTS) with Allwinner H2+ and I have hooked up a uart usb converter to read the booting.Code:[ OK ] Reached target sockets.target - Socket Units.Starting armbian-hardware-monit…ce - Armbian hardware monitoring...Starting armbian-hardware-optim… - Armbian hardware optimization...Starting armbian-resize-filesys…vice - Armbian filesystem resize...[ OK ] Finished armbian-hardware-monit…vice - Armbian hardware monitoring.[ OK ] Finished armbian-hardware-optim…ce - Armbian hardware optimization.It seems to stop around here it doesn't completely boot and I can't ssh because of incomplete booting as its not obtaining IP address.Before I had a bookworm image which did boot and I was configuring it and I got the locales option and it got stuck there from which it doesn't boot now even with old images or the newer onesI also have another image showing it just shows starting kernel and that's it. It doesn't show up on my network.
Ordinary Relay Hardware Modified Into Latching Relay - Page 1
Forum section: electronics / projects

author: Kedar264
author_rank: Regular Contributor
timestamp: June 19, 2015, 09:10:02 am
content: Turn normal electric relay into latching relay only using neodymium magnetJust open the relay and stick an neodymium magnet on to common terminal and that's all.....!You can use this latch as memory, switch, etc.This Modified relay doesn't need continues power ,input pulse is sufficient to latch the relay in one of the two states.Watch this Modificationhttps://youtu.be/SxRl7rMPGRk

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: June 19, 2015, 06:38:13 pm
content: That's pretty neat. Definitely something to file away in the old gray matter.

author: rolycat
author_rank: Super Contributor
timestamp: June 19, 2015, 06:48:27 pm
content: Havinganothersuck of the sav, Kedar?
ORG4475 GPS - bias-T problem - Page 1
Forum section: electronics / projects

author: poorchava
author_rank: Super Contributor
timestamp: June 03, 2014, 09:30:21 pm
content: I'm designing a circuit which will include an ORG4475 module and an active antenna. The datasheet states that:Quoteand an application schematic in module datasheet looks like this:but when I look at the evaluation kit schematic I see that:Have anyone of you guys had any experience with that? is it typical for such an RF device to have an internal colupling capacitor?

author: edpalmer42
author_rank: Super Contributor
timestamp: June 03, 2014, 10:00:29 pm
content: Since you have to send DC up to an active antenna, the RF input has to be DC blocked somewhere to keep from shorting out that path.The datasheet states that the RF input is DC blocked up to 10V (Sec. 17.3).The schematic shown in the datasheet is a generic one that works for any antenna. Note that Vant isn't defined on that drawing. So if you happened to have a 12V antenna (I've heard of them, but never seen one) it would be fine because of the external capacitor. The schematic in the evaluation kit is for that specific implementation. The input voltage is specified as 5V so the internal capacitor is adequate.Ed

author: Wilksey
author_rank: Super Contributor
timestamp: June 03, 2014, 10:08:16 pm
content: The series capacitor is generally used for impedance tuning, I use them in 2.4GHz module designs.
Origins of CRY4_3R20X2R50X0R80 ? - Page 1
Forum section: electronics / projects

author: Debugging
author_rank: Contributor
timestamp: April 28, 2023, 01:44:55 am
content: You can find this in some schematics. It seems 3R20 etc is some kind of notation for the width/height/length.But what is CRY4? Where did this CRY4 and notation originate from ? It looks like it is mostly used for a resonator.

author: ataradov
author_rank: Super Contributor
timestamp: April 28, 2023, 03:00:26 am
content: 4-pin Crystal. Just a generic name for an SMD crystal.R is commonly used to denote the period. So, the size is 3.2mm x 2.5 mm, height is 0.8 mm. A very typical size for a crystal.

author: Nominal Animal
author_rank: Super Contributor
timestamp: April 28, 2023, 08:29:13 pm
content: I fully agree with ataradov above.I recognize the image as being of a schematic created inEasyEDA (Std). In this case:Y2is theprefixin EasyEDA24MHzis the componentnamein EasyEDACRY4_3R20X2R50X0R80is the componentfootprintin EasyEDA(only one by this footprint name exists, and was created by user kwankiu)There is recommendedfootprint naming rule (autotranslated PDF)in EasyEDA – because all footprints you create are visible to other users as well –, but kwankiu used somethingsimilarinstead. According to the rule, a better footprint name would have beenOSC-SMD_4P-L3.2-W2.5-TL(I think, according to rule "OSC-SMD_P-L-W-TL/TR/BL/BR" for case 1.1.8 in the PDF).I don't know which one (the recommended or kwankiu's) is "better", because both are similarly easy to read for me.
ORing 3 DC Power Supplies - Page 1
Forum section: electronics / projects

author: elimenohpee
author_rank: Contributor
timestamp: August 23, 2018, 05:58:20 pm
content: I have an application where I have 3 DC power supplies coming from different sources (i.e., different phases of a 3 phase delta transformer). I want to create a DC bus where any DC load will be evenly shared between all 3 power supplies. There are ORing chips available that allow load sharing for 2 DC power supplies:LTC4370 - Two-Supply Diode-OR Current Balancing Controllerhttp://www.analog.com/en/products/ltc4370.htmlI can't find a similar chip that would allow 3 DC inputs with a single output. Is anyone aware of a chip that supports 3 DC inputs? I realize this isn't a common request which is why I doubt there is an off the shelf solution. If not, would it be possible to build something like this based on using these chips?

author: mikerj
author_rank: Super Contributor
timestamp: August 23, 2018, 06:39:40 pm
content: Have a search for "load sharing controller", there are quite a few single channel devices around e.g.ucc29002so you can gang up as many sources as you want.

author: elimenohpee
author_rank: Contributor
timestamp: August 24, 2018, 11:18:23 am
content: Perfect, that's exactly what I was looking for. Thanks

author: ocset
author_rank: Super Contributor
timestamp: August 25, 2018, 01:38:22 pm
content: Its worth remembering that when you have multiple power supplies load sharing with those load sharing chips, they are each getting the sense voltage altered in some way so that they share….but the adjustment takes place at a certain bandwidth….and so you can affect the transient response….sometimes its easier, and gives a better transient response to have multiple current mode SMPS’s all having a single error amplifier to control the threshold voltage of a single PWM comparator which acts for all supplies….that very often will give you the best transient response....if you think about it, its even a bit like a full bridge smps....a full bridge is just two interleaved 2-transistor-forward converters with a single error amplifier.Another way is as attached…to have a single PSU being master….and setting vout…then multiple slaves simply read the masters current , and copy that current…that also can give you a nice transient response..So basically, the load sharing chips will have a certain bandwidth in its loop, and if youre not careful, the loops can interfere with each other and you can get instability…because don’t forget each smps already has its own feedback loop………you don’t wat to end up with two different feedback loops fighting each other.