hybridfree/eevblog-posts huggingface dataset:
smps no output - Page 1
Forum section: electronics / beginners

author: ravi6545
author_rank: Newbie
timestamp: March 21, 2024, 10:01:29 am
content: I used TNY267 IC in my SMPS without connecting load the output is coming. but when i connect a load it's not working (it comes like ON and OFF). when i check PWM of the IC it shows fluctuating not constant signal. but i change the IC then also the same thing is coming so problem is not with a IC but only thing it doesn't give the correct PWM output. see the circuit attached.

author: timenutgoblin
author_rank: Regular Contributor
timestamp: March 21, 2024, 02:19:37 pm
content: 1N4007 rectifier diode is not suitable for 132kHz SMPS circuit. Try using 1N5819 or 1N5822 Schottky rectifier diode.
SMPS Power Supply design review - Page 1
Forum section: electronics / beginners

author: Warsp
author_rank: Contributor
timestamp: January 21, 2023, 10:10:47 pm
content: Hello all.Since this the first time I have designed an SMPS, I would like someone to look over the schematic to see if I did something stupid that would cause something to go wrong. Output voltage is ~170V and +5V. All resistors are 1/4W and all capacitors have a suitable voltage rating. I plan on breadboarding and eventually making a PCB for this design so I would like to improve the chances of this working first try. All help and suggestions are appreciated.

author: Benta
author_rank: Super Contributor
timestamp: January 21, 2023, 10:34:07 pm
content: Looks a bit strange...The NCP1072 is designed as a flyback converter, but you seem to be using it in forward mode.And is it OK that your 170 V are not isolated from the mians? I don't know your application, but that seems potentially dangerous to me.

author: Warsp
author_rank: Contributor
timestamp: January 21, 2023, 11:10:29 pm
content: The design I made is based off of a design in the NCP1072 datasheet, so I think it would work fine. As for isolating 170V would I be able to just use a choke since it is similar to a 1:1 transformer? I am only going to be drawing ~6mA and I could probably wire it to the NCP1072 mosfet. I know that chokes are not made for this use and are pretty inefficient but for what I am using it for would it work?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2023, 11:50:06 pm
content: Yeah transformer phasing is backwards. Take a close look at the dots on the windings! Double check the transformer datasheet as well.VD doesn't have a ground reference to the connector, and is mains referenced, as mentioned. Better to just not do it at all. If you're doing like nixies or something, better to use a secondary side boost/flyback, yes, more stages, who cares, it's low power.C? is way too large, I... oh, no designators. The 22nF GND-GND one. Too much ground leakage.L? 10uF is pretty large, probably doesn't matter but 1uH would be enough. Depending on what you're running, it might not be needed at all (and the second cap).The 0.1 compensation cap may want a resistor in series. Even if you don't end up using it (0-ohm jumper), good to have the option.Cheers!Tim
SMPS simulation - Page 1
Forum section: electronics / beginners

author: slashguitar
author_rank: Contributor
timestamp: November 17, 2012, 06:37:28 pm
content: Hi,I want to build an output adjustable flyback converter(off line) to work as a tracking preregulator for a lab powersupply. Unfortunately a wasn't able to find any simulation models for ICs likeTEA1552.Any suggestions for ICs/Simulation software?Thanks

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 17, 2012, 07:05:31 pm
content: LTspice, and look at the demo circuits, lots of flyback stuff:http://www.linear.com/designtools/software/demo_circuits.php

author: free_electron
author_rank: Super Contributor
timestamp: November 17, 2012, 07:13:12 pm
content: Quote from: slashguitar on November 17, 2012, 06:37:28 pmnot a chance to get the models of such things.... besides you will need a lot of horsepower to simulate a dynamic system like an SMPS. the stabilisation run may take seconds and to actually sutdy it under impulse load etc will take very long simulation runs with massive datasets as output.

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 17, 2012, 07:49:09 pm
content: One second simulation time for 1ms run time, not bad(so 20 seconds total)

author: BravoV
author_rank: Super Contributor
timestamp: November 17, 2012, 08:00:16 pm
content: Quote from: PA0PBZ on November 17, 2012, 07:05:31 pmThough there are tons of switching circuit simulations for various topologies in LTSpice, the op is asking specifically about TEA1552 which is a NXP chip, don't think LTSpice will have that in their library even in the future, unless somehow NXP is acquired by Linear or vice versa.

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 17, 2012, 08:05:24 pm
content: QuoteNote the 'like'... I'm aware that NXP will not be in LT's library but he didn't say it had to be NXPIf you want to simulate SMPS there's not much choice afaik, and LTspice is free...
SMPS Solar Voltage Regulator Circuit Suggestion - Page 1
Forum section: electronics / beginners

author: ric96
author_rank: Newbie
timestamp: May 03, 2015, 09:15:04 am
content: I have a 30W 12v solar panel which i would be using to charge a 12v 7.2Ah Battery.I require a SMPS 12v-20v to 5v regulator to charge phones from that battery or the panel. The output can be any where between 1A to 2.1A.I have tried using things like the (in)famous L7805 but its not at all efficientCan someone suggest me something simple to construct?Thank You!*My skill level, Can Make Simple Circuits If Well Labeled and Described*

author: mikerj
author_rank: Super Contributor
timestamp: May 03, 2015, 09:43:29 am
content: Why not just buy a car phone charger? They all have switch mode regulators, are pretty efficient, are cheap, apply the correct voltages to the USB data lines and even come with the correct connector for your phone.

author: ric96
author_rank: Newbie
timestamp: May 03, 2015, 10:09:01 am
content: Quote from: mikerj on May 03, 2015, 09:43:29 amBecause i am keen on making on my own ... Its been almost 4 yrs since i haven't done any circuitry at all...!
SMPS Transformer winding diagram - Can this be used in any way I choose? - Page 1
Forum section: electronics / beginners

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: September 12, 2021, 02:22:42 pm
content: Below is a diagram of a commercially available transformer for SMPS and DC to AC power conversion.Do I have to use ALL the pins or can I use just the ones circled in green or any combination I choose as long as I choose a Primary and Secondary ?Thanks

author: Terry Bites
author_rank: Super Contributor
timestamp: September 12, 2021, 03:30:37 pm
content: You can choose and leave unused windings open or join them in series if you observe winding direction. How you choose for your application is a different and rather complcated matter though.

author: fourtytwo42
author_rank: Super Contributor
timestamp: September 12, 2021, 05:51:32 pm
content: Depending upon your application you may need to be aware of the insulation provision between windings. For example if you are designing a mains powered SMPS with safe low voltage secondaries you must ensure the transformer primary and secondary side intention is maintained. You cannot use two secondaries as mains and low voltage side nor two primaries.Often a winding is provided on the primary side for powering the controller, this cannot be used as a general purpose secondary as it has insufficient insulation wrt primary. However only using one of two available secondaries is quite acceptable.

author: Jwillis
author_rank: Super Contributor
timestamp: September 13, 2021, 02:39:06 am
content: You also need to be aware , if your not already , that the size of the SMPS transformer are designed with the frequency to which it will be operating at . The higher the frequency the fewer the windings and the smaller the core. If the number of windings is to few and the core to small for a frequency that you will be operating it at , it willl either get quite hot or if the proportions are really far off it will burn up. Each model of SMPS has a frequency range .

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 13, 2021, 03:55:33 am
content: I mean, you can use it however you like, given that it doesn't burn up -- it just might not be very practical using say the lone 5t winding as primary and the rest as secondaries, if I'm to have a guess at resistances here. The power handling of each winding will be more evident from DCR and leakage inductance measurements. (Which I'm guessing you have, hence knowing the 5/8T isn't another 5+3 tapped winding?)Or what, is this provided by the manufacturer? Like, an Ali special or something? The hand-scrawled drawing would figure, wouldn't it...Tim
SMPS - Why there is ringing on secondary ?  - Page 1
Forum section: electronics / beginners

author: MacIntoshCZ
author_rank: Regular Contributor
timestamp: November 22, 2023, 04:18:47 pm
content: Hello,Can someone explain why there is ringing on secondary side (before caps)? Its loaded with aprox. 30R Halogen lamps on 100V at the moment. Its fullbridge converter 100V/40A. I even tried to simulate this and its also in simulations, RC snubbers removed high frequency ringing but this 1,1Mhz remains.Also it rings only when voltage is rising. Qp1 probe is marked as 1 in schematic, QP2 probe is marked as 2.Switching frequency is aprox 50Khz, tl494 driver. I think it should look like that, i just dont understand why.Thanks for help

author: boB
author_rank: Frequent Contributor
timestamp: November 22, 2023, 04:47:18 pm
content: From first glance, looks pretty much normal for a discontinuous mode inductor.Usually from parasitic L-C and not enough load. Parasitics here are really small values except for the inductor.Typically, just some ringing that doesn't over-voltage any components are fine and don't need to be dealt with.Bring that 100K load R down to where it is always drawing some current and the ringing should delay or go away.boB

author: radiolistener
author_rank: Super Contributor
timestamp: November 22, 2023, 04:58:18 pm
content: it happens due to impedance mismatch between secondary coil and load on high frequency.

author: MacIntoshCZ
author_rank: Regular Contributor
timestamp: November 22, 2023, 05:08:35 pm
content: Quote from: boB on November 22, 2023, 04:47:18 pmYes, i forgot to mention that this ringing goes away with higher loads.Quote from: radiolistener on November 22, 2023, 04:58:18 pmOk, I had readen in somo books that when medium has different characteristic impedance, than wave reflections happens. But how exactly this works right there i dont know
SMPS/POWER - Page 1
Forum section: electronics / beginners

author: Tapanaa
author_rank: Newbie
timestamp: May 05, 2022, 01:10:13 pm
content: I need a guide to modify a smps to run on 48v dc input. Or Is it possible to modify off the shelf dc dc buck converter to run on more than 40v dc. I have several Lm2596 boards which has maximum 40v input specs. I need output 5v 1A.

author: Ice-Tea
author_rank: Super Contributor
timestamp: May 05, 2022, 02:07:02 pm
content: These boards are spec'd to 40V because that is what the LM2596 is capable of. You could extend the range by putting a zener in series but- that will greatly reduce your efficiency- burn several watts in that zenerYou should be looking for a module and/or IC that does 48V (and on top of that a healthy margin) and start from there...

author: Gyro
author_rank: Super Contributor
timestamp: May 05, 2022, 05:36:18 pm
content: Double post...https://www.eevblog.com/forum/renewable-energy/48v-input-5v-1aout-smps-modification-idea-needed/
SMSC 8720A help id component - Page 1
Forum section: electronics / beginners

author: u666sa
author_rank: Frequent Contributor
timestamp: October 11, 2025, 12:00:26 am
content: SMSC8720A1452346BKRBefore you say LAN transceiver.. I replaced 4 of these on a sound board today. It must have to do something with sound, not ethernet.

author: jwet
author_rank: Frequent Contributor
timestamp: October 15, 2025, 02:47:26 pm
content: SMSC was purchased by Microchip a while back though this is only identified as SMSC. They specialize in Automotive interfaces.The 8720A is a small 10/100 ethernet PHY (just the physical interrace). These were used in automotive and elsewhere to route I2S or MOST like multimedia signals to remote units. MOST is usually done over fiber. Some systems used twisted pair and used these kind of PHY's for wire interface. SMSC also does MOST stuff. They are know to be a bit fragile in automotive.
SMT parts on a breadboard - Page 1
Forum section: electronics / beginners

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 08, 2014, 03:02:24 am
content: The part I'm looking at shows this:Package/Case -- 32-WFQFN Exposed PadSupplier Device Package -- 32-MLPWhat are some of the ways to test this out on a breadboard? It would be great not have to solder/desolder I found some adapters but they're pricey.http://www.mouser.com/access/?pn=945-IC550-0484-004-Ghttp://www.aliexpress.com/item/Free-shipping-Universal-IC-Adapter-Socket-LQFP-TQFP-QFP-32-to-DIP-28-TQFP32-QFP32-to/1282631956.htmlhttp://www.adafruit.com/products/1240#DescriptionWondering what the typical solution is for this problem.

author: lgbeno
author_rank: Frequent Contributor
timestamp: February 08, 2014, 03:20:46 am
content: Best bet is to either bit to bullet and solder it to a qfn32 to dip adaptor or find a preassembled breakout board on spark fun. Tindie, eBay, etc for the device that to want to test.I would not go the socket approach.What part is it anyway, surely someone of this forum has used it and might have some breakout board in mind.

author: Fsck
author_rank: Super Contributor
timestamp: February 08, 2014, 04:00:29 am
content: basically 2 effective choices as you found out. a solderable breakout board:http://www.adafruit.com/products/1163or your socketed board. You can get some for possibly slightly cheaper on ebay. seems to be, if you use the socket like 20+ times, it's paid for itself over the solderable breakout.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 08, 2014, 05:38:52 am
content: With things trending toward SMT I'm surprised there aren't more solutions/options. I may try to make one that are pressed in by hand then extracted with the special tool that goes in at the corner. It's cheaper at least. I was looking for something like those simple ZIF sockets used for CPUs.I think there's a lot of room for improvement on the current offering of solutions for doing SMT with breadboards.

author: amyk
author_rank: Super Contributor
timestamp: February 08, 2014, 12:24:22 pm
content: Quote from: GiskardReventlov on February 08, 2014, 05:38:52 amPLCC socket? Those probably won't work for any *FN package.There are QFN sockets that work on the same principle as BGA ones, butthey tend to be rather expensive.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 08, 2014, 09:13:20 pm
content: Quote from: amyk on February 08, 2014, 12:24:22 pmI thought I saw a part that allowed a *FN package to be pressed in then extracted with a small tool. It's very possible that I was looking at a PLCC socket. I need to find a page that has hi-res photos of the different types because the data sheet photos are not real photos they are just renderings.
SMT Pin 1 Marking - Page 1
Forum section: electronics / beginners

author: admiralk
author_rank: Regular Contributor
timestamp: January 25, 2020, 07:58:55 pm
content: This might win the prize for stupidest question ever, but this is my first time trying to solder SMT parts. I went to put a 74HC595 on the board and did not see a dot or cutout to indicate pin 1. There is a bar on one end, though, that I would logically assume for pin one. Is that the pin marking, or just part of the graphics?And just for reference, I attached a blurry picture of the chip.

author: mc172
author_rank: Frequent Contributor
timestamp: January 25, 2020, 08:05:45 pm
content: Yes, the bar/line indicates where pin 1 is. The package has also got a chamfer on one side which confirms pin 1.

author: admiralk
author_rank: Regular Contributor
timestamp: January 25, 2020, 08:32:21 pm
content: Much thanks!I won't tell you how long it took me to find the chamfer.
RF connectors on modern high-frequency boards. - Page 1
Forum section: electronics / beginners

author: Anquietas
author_rank: Regular Contributor
timestamp: March 07, 2013, 08:41:18 am
content: This is way above my level of understanding, but lately I have seen quite a few boards like this one,http://2.bp.blogspot.com/-YDXGoMEhKk4/TnxkgF0gNzI/AAAAAAAAAho/9AOlVbZfa3I/s1600/Multi-Core_Mainstream_Computing_Pushed_to_Extremes_HMC3.jpgwith many RF connectors and I would like to know what reasons there could be to design a board like that. What are these coaxial connectors for? Are these high-frequency / high signal integrity test points on prototypes that aren't included in the final product?

author: Rerouter
author_rank: Super Contributor
timestamp: March 07, 2013, 08:46:46 am
content: the fact that those chips look like engineering samples and are to some extent socketed, would lead me to think that yes that is a prototype with high integrity test points,

author: w2aew
author_rank: Super Contributor
timestamp: March 07, 2013, 07:42:21 pm
content: Quote from: Anquietas on March 07, 2013, 08:41:18 amOften time, IC manufacturers will provide demonstration board (demo boards, evaluation boards, etc.) for the chips/devices that they make. They'll make these available to customers to allow them to evaluate the chip without them having to go through the trouble of designing a board to test the chip. High performance / high speed devices can't be properly tested or evaluated on plug-in breadboards or protoboards, so these types of custom evaluation platforms are necessary to allow customers to run their signals in/out of the circuits/chips to test and evaluate them for their application. Often, this means coupling very high speed (RF, high speed digital, etc) signals on and off the board - hence the RF connectors.

author: KJDS
author_rank: Super Contributor
timestamp: March 07, 2013, 08:04:43 pm
content: I've seen plenty of first iteration boards with a lot of connectors on like that. If you have ten blocks of RF on one board, you want to test each individually and with clusters of them working together.

author: FenderBender
author_rank: Super Contributor
timestamp: March 07, 2013, 10:09:43 pm
content: My old cellphone had atleast 4 mini RF connectors like those on it. I supposed one could be for some sort of antenna perhaps, but the others, I am not sure.

author: w2aew
author_rank: Super Contributor
timestamp: March 08, 2013, 03:25:58 am
content: Quote from: FenderBender on March 07, 2013, 10:09:43 pmCould be used during final test / alignment / verification / etc. as part of the manufacturing process.

author: FenderBender
author_rank: Super Contributor
timestamp: March 08, 2013, 05:21:33 am
content: Oh yes surely, just seemed a rather expensive(?) method for a production item, though I suppose it's probably not in the long run.
SMT tactile switch (SPST) with no ground connection - Page 1
Forum section: electronics / beginners

author: newtekuser
author_rank: Frequent Contributor
timestamp: October 06, 2023, 03:04:50 am
content: This SMT tactile switch has no ground terminal according to the datasheet, but once I import the symbol into Kicad it tells me one of the pins is not connected. If this button requires no ground, where does the other pin connect to? I thought these switches only require one of the pins connected.Also, what does the dot represent on the footprint?https://www.mouser.com/ProductDetail/611-PTS526SK15SMR2Lhttps://www.snapeda.com/parts/PTS526%20SM08%20SMTR2%20LFS/C%26K/view-part/?ref=search&t=PTS526%20SK15%20SMTR2%20LFS

author: ataradov
author_rank: Super Contributor
timestamp: October 06, 2023, 03:17:00 am
content: What would it do with only one pin connected? Switch shorts together two pins. What you connect to those pins is up to you.You may want to provide exact error messages you are getting too.

author: newtekuser
author_rank: Frequent Contributor
timestamp: October 06, 2023, 03:29:35 am
content: Typically I connect one pin to ground and the other to a resistor and/or some pin on the MCU.

author: ataradov
author_rank: Super Contributor
timestamp: October 06, 2023, 03:34:59 am
content: Ok, so what is stopping you from doing that now? Can you actually describe your problem?

author: newtekuser
author_rank: Frequent Contributor
timestamp: October 06, 2023, 03:44:03 am
content: Of course I can connect it to ground, but I was just wondering because the datasheet says it doesn’t have a ground connection. I thought that I could just leave the other pin from the symbol floating but kicad throws a not connected pin error.

author: ataradov
author_rank: Super Contributor
timestamp: October 06, 2023, 03:46:30 am
content: No switch has ground connection. They are just passive devices. If your design needs to have something connected to the ground when a button is pressed, then you wire it accordingly. It does not have to be ground, but it has to be something.

author: newtekuser
author_rank: Frequent Contributor
timestamp: October 06, 2023, 04:17:20 am
content: I did not give this much thought until now when I saw the no ground in this datasheet, but now I see other spst switches including the one I’ve been using have no ground pins.I’ve been connecting them this way since long time ago by copying others:https://youtu.be/wgn3ujP2Ka0?si=0EQ-gh29WR7Fzd5I

author: ataradov
author_rank: Super Contributor
timestamp: October 06, 2023, 04:22:01 am
content: Yes, this is one way to use the switch. This is not the only way, of course.If you look in the datasheet, you will see that the ground pins on the versions that have them are purely passive. They are there either for mechanical reasons, or to ground the exposed metal parts for ESD reasons. Both uses seem pretty pointless, no idea why they would make them like this.
SMT Today January edition out now (free electronics industry magazine) - Page 1
Forum section: electronics / beginners

author: acarpenter
author_rank: Contributor
timestamp: January 30, 2014, 11:31:40 am
content: This issue of SMT Today focuses on test and inspection, includes an interview with CEO, Glenn Qiu and a preview of next month’s Apex expo in Las Vegas.The new magazine is currently available for free digital download fromwww.smttoday.com&http://smttoday.com/magazine/enjoy
SN100C vs. K100LD solder? - Page 1
Forum section: electronics / beginners

author: stuartk
author_rank: Regular Contributor
timestamp: September 15, 2018, 12:37:49 am
content: I'm tired of the dull looking joints I get when I solder with SAC 305. I've heard that both Kester K100LD and the Nichon Superior/Aim Solder/Stannol SN100C, are both cheaper and better, both in terms of cosmetic performance and improved wetting.Apparently both of these alloys reduce tin whiskers, corrosion and thermal cracking.Has anyone use both of these solders and come to a comparison as to which one to buy?A couple of local shops have some offerings:$41 canuck bucks for a full pound of the K100LD stuffhttps://www.accessotronik.com/product_p/24-9574-1402_k120.htm$32 for a 1/2 pound of SN100Chttps://www.diverseelectronics.com/products/Solder-Wire-0-8mm-032-SN100C-LF-No-Clean-p8066/I'm trying to find a source for a 10g syringe of paste, not an expensive tub of the stuff. So far no luck.Any suggestion as to which one to use or where to get a person sized supply of paste? Thanks,Stuart
SN74abt16623 - Page 1
Forum section: electronics / beginners

author: Simbarashe Bryne Chipembe
author_rank: Contributor
timestamp: June 26, 2015, 03:36:40 pm
content: Hi guys I am trying to use the SN74abt16623, question is I don't understand how you make it store or "latch" data. eg latch A data on b bus and keep it there, even when A data changes ( not transparent)

author: tggzzz
author_rank: Super Contributor
timestamp: June 26, 2015, 03:47:37 pm
content: Read page 1 of the datasheet, which says..."The dual-enable configuration gives the transceivers the capability of storing data by simultaneously enabling OEAB and OEBA. Each output reinforces its input in this configuration."

author: w2aew
author_rank: Super Contributor
timestamp: June 26, 2015, 03:49:35 pm
content: According to this description in the datasheet:QuoteIt sounds like they can only latch data from their own busses, and only do it simultaneously.

author: DJohn
author_rank: Regular Contributor
timestamp: June 26, 2015, 04:03:01 pm
content: Storage is explained in the second paragraph of the first page of the datasheethttp://www.ti.com/lit/ds/scbs211b/scbs211b.pdfHave your external circuit drive one side or the other to the value you want to store, then assert both output enables (OEAB high and /OEBA low). Then you can tri-state your external circuit, and the transceiver will hold the value.You end up with two devices driving the bus in between asserting the output enables and tri-stating your driver, but that's OK as both will be driving the same value.What it can't do is store data while the bus on either side is driven to different values ("even when A data changes"). That will make either it, your other driver, or most likely both, very unhappy.A small CPLD might be your best option, if you need it bidirectional and able to store data while the input side changes.
sn74ls86n IC output voltage lower than 5v - Page 1
Forum section: electronics / beginners

author: Elyxircuit
author_rank: Newbie
timestamp: February 22, 2022, 03:35:43 am
content: When using a sn74ls86n IC (powering it correctly) when I input 5v to input 1A, and ground to input 1B I measure output 1Y as 3-4v. Can anyone help explain why the output is not 5v?

author: retiredfeline
author_rank: Frequent Contributor
timestamp: February 22, 2022, 03:47:06 am
content: Shhh, no need to shout.Because it's has a TTL output stage with totem-pole transistor configuration so it doesn't go all the way to 5V. In 5V TTL, logic 1 is defined as > 2.4V.See the typical output schematic in this article:https://en.wikipedia.org/wiki/Transistor%E2%80%93transistor_logic

author: Elyxircuit
author_rank: Newbie
timestamp: February 22, 2022, 04:14:13 am
content: If logic 1 is > 2.4V, then if one of the inputs to the ic is > 2.4v then will it still count as a logic 1 to the ic?

author: TimFox
author_rank: Super Contributor
timestamp: February 22, 2022, 04:40:26 am
content: Two important specs for any digital gate:VIHminis the minimum input voltage that is guaranteed to be recognized as logic 1.VOHminis the minimum output voltage that is produced for logic 1.Obviously, for this to work reliably,VOH>VIHLook at the data sheet for these values and the conditions under which they are specified (such as input current, etc.)For most CMOS familes,VOHminis close to the positive supply voltage, but for TTL the guaranteed output is considerably lower.

author: CaptDon
author_rank: Super Contributor
timestamp: February 22, 2022, 02:22:11 pm
content: I guess you don't work with 74XX I.C.'s much, even the spec sheet says it won't go to +5vdc. Look at those nifty things called datasheets.Turn off the CAPS, you know better......Unless you are using an ancient 1940's teletype machine for your terminal, then you may not have a choice.

author: TimFox
author_rank: Super Contributor
timestamp: February 22, 2022, 02:34:40 pm
content: By the way, if you need to drive a CMOS input from a TTL output, both on +5V supply, a resistor from the TTL output to +5V (roughly 10 k) will pull up the voltage higher to match the somewhat higher input voltage requirement of the CMOS input. This is a quantitative question, so look at the data sheets to determine voltage requirements and current capability of the output.
SN74LVT245B - what for? - Page 1
Forum section: electronics / beginners

author: davemisbehave
author_rank: Unknown
timestamp: July 12, 2013, 12:19:45 pm
content: While looking at TIs evaluation module for its THS56X1 series DACs I came across the SN74LVT245B . I (think I) understand what it does, but I'm not sure why it is necessary. Why not just have a direct connection from the DSPs bus to the DACs digital inputs? What would one need bus transceivers for, both in this application and in general?I have included a picture of the relevant part of the circuit as an attachment. It can also be found on page 24 of the evaluation modules user guide.THS56X1EVM User's Guide:http://www.ti.com/lit/ug/slau032c/slau032c.pdfTHS5661A datasheet:http://www.ti.com/lit/ds/symlink/ths5661a.pdfSN74LVT245B datasheet:http://www.ti.com/lit/ds/symlink/sn74lvt245b.pdfTIA!

author: Skimask
author_rank: Super Contributor
timestamp: July 12, 2013, 02:43:54 pm
content: So you can tristate the bus so the bus can do other things while you're not reading/writing to the DAC.Otherwise, you'd need 16 more dedicated lines just for the DAC.

author: davemisbehave
author_rank: Unknown
timestamp: July 12, 2013, 02:54:15 pm
content: Thanks, it all makes sense now!

author: SeanB
author_rank: Super Contributor
timestamp: July 12, 2013, 03:38:33 pm
content: Another common use for bus drivers on a DAC is to isolate the DAC inputs from the bus so that the data from the other MCU activity on the input will not show up as noise on the output. Often used on higher resolution devices, along with having a separate dedicated digital supply for the bus driver, just to get the noise figure closer to the thermal noise of the DAC and reference. Adds an extra gate delay, and needs a separate enable pin to drive it from the address decode logic, but gives a stable data drive to the DAC latches.
Snap-On Counselor MT1665 oscilloscope - Page 1
Forum section: electronics / beginners

author: sycho123321
author_rank: Regular Contributor
timestamp: December 09, 2014, 01:45:51 am
content: Hi all,I know this scope is automotive but i can snag it for 10$ but want to know if it would work as a normal o-scopeThanks!,Lukas

author: ovnr
author_rank: Frequent Contributor
timestamp: December 09, 2014, 02:11:55 am
content: I really, really doubt it. Get a normal o-scope instead, even if it's just $10 - or buy it for a teardown; if it ends up working out as a scope, lucky you? It's just $10.

author: Vgkid
author_rank: Super Contributor
timestamp: December 09, 2014, 03:08:22 am
content: I would agree with ovnr, but it does look really cool.buy it and tear it down.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 09, 2014, 09:04:19 am
content: I'll even mail you $10. But be forewarned, it'll have a picture of Sir John A. MacDonald on it.

author: mikerj
author_rank: Super Contributor
timestamp: December 09, 2014, 10:33:00 am
content: It does have a normal voltage input function, but I suspect timebase and bandwidth will be very limited. It's targeted purely for automotive work, so has RPM and dwell functions and very high voltage probes for HT measurments. For $10 it would be well worth having if you work on your own cars.I found ascanned copy of of the manualif it helps.

author: xwarp
author_rank: Frequent Contributor
timestamp: December 09, 2014, 12:37:41 pm
content: If it doesn't have all the leads, then it's worthless for anything other than tearing it down to see what makes it tick, and even then, there isn't much in them that can be considered fascinating.If it does have all the leads, then test it on an available vehicle and see if it works.If it doesn't work, forget locating any type of service info for them.I have a MT1665 also and while it does work, I wish I could locate a service manual for the thing.If you get it just to tear it apart, let me know if you are in the U.S. as I'd seriously consider buying parts from yours.

author: sycho123321
author_rank: Regular Contributor
timestamp: December 10, 2014, 12:41:06 am
content: Somebody bought it before i called the guyBUT xwarp i found a manual for youhttp://captfiero.com/uploads/
Snow Blower Lights - Page 1
Forum section: electronics / beginners

author: lefty
author_rank: Contributor
timestamp: February 02, 2020, 10:44:59 pm
content: I'm thinking of hooking up an LED light bar to my snowblower. The machine has a 12V battery used for starting the machine. I wanted to hook up a light bar directly to the battery. I'm not sure how to spec it out. I'm new to the arena so I'm just trying to apply my very limited knowledge. When running, the voltage difference at the poles is 16.5 V as there's a charging system for the battery when the machine is running. Does this mean that I need to be looking at 16.5 volts for the lights? I've seen some instructionals on the internet for snowblower lights including a rectifier and capacitors but this seems to be for a batteryless system and alternating current.Thanks.

author: Nerull
author_rank: Frequent Contributor
timestamp: February 02, 2020, 11:00:15 pm
content: A light bar intended for installation in a vehicle should already be designed to handle alternator charging voltage. Typical vehicles are very-very approximately 12V. That voltage varies by alot, and anything designed to installation in a car must be able to handle that.

author: lefty
author_rank: Contributor
timestamp: February 02, 2020, 11:05:21 pm
content: thank you

author: JPNH20
author_rank: Contributor
timestamp: February 03, 2020, 06:59:19 pm
content: I put two of these on my blower. They work in a pinch and are cheap.https://www.harborfreight.com/200-Lumen-LED-Super-Bright-Flip-Light-63922.html

author: lefty
author_rank: Contributor
timestamp: February 03, 2020, 07:27:24 pm
content: I love those things. I have them everywhere in my house.
SNR on amplifier - Page 1
Forum section: electronics / beginners

author: Simon
author_rank: Unknown
timestamp: February 20, 2021, 09:38:35 am
content: Well it's that time again of doing my now HND course assignment which as always is in monkey see monkey do fashion given the very selective information in the course module. This one is causing me a dilema around powers and voltages.QuoteSo firstly as the source impedance has not been specified (this figures in the modules calculations) so I would assume also 75 Ohms. So do I assume the amplifier see's the full 5 dBmV and 20 dBµV or half due to the cable also having an impedance of 75 Ohms (I assume).To convert from dBmV to dBµV I am unsure if I add 30 or 60 dB. I gather that 20 log V/µV is caveated by the impedances being the same which is standard.If i assume 60 dB then that does make my noise ratio more plausible. So the 5 dBmV is 65 dBµV, this makes sense as knowing how these people operate they like to make things all tie together to help you see if you are getting it right at 65 dBµV is the answers toe tthe previous question about the same amplifier asking for the maximum permissible input given the specs.Does the SNR change whether expressed in dBmV or dBmW ? I guess being a ratio no as all things being equal the ratio is the same.

author: pwlps
author_rank: Frequent Contributor
timestamp: February 20, 2021, 02:17:42 pm
content: Input SNR is 65dBµV-20dBµV=45dB, if NF=6dB the output SNR is 45+6=51dBedit: oops! 45-6=39dBQuote from: Simon on February 20, 2021, 09:38:35 amSNR is expressed only in dB, not dBmV or dBmW. dBmV or dBmW express the power level as a ratio (thus expressed in dB) to some fixed level (mV, mW, uV etc.). SNR is already a ratio, so it's in dB. Hence the strange arithmetics rules : dBmV-dBmV=dB

author: Simon
author_rank: Unknown
timestamp: February 20, 2021, 02:31:34 pm
content: They want the outputI thought about doing it like that but the 6dB I assume is on power so can you add/subtract dBW and dBV like that? I came up with 39dB of SNR after converting to voltage,so 85 dBµV - 6 - (20+20) = 85-46 = 39 dB which was my result.

author: pwlps
author_rank: Frequent Contributor
timestamp: February 20, 2021, 02:38:42 pm
content: Yes, I corrected my error. Doesn't matter if you convert to V,W, mV,mW etc., it's always a power ratio.

author: Simon
author_rank: Unknown
timestamp: February 20, 2021, 04:31:06 pm
content: Yea I realised this is why with volts the dB doubles to make it equivalent to power which is proportional to the square of the voltage. In log math a power operation becomes a multiplication.
Snubber Capacitor for a AC coil - contactor - Page 1
Forum section: electronics / beginners

author: golash
author_rank: Contributor
timestamp: November 11, 2014, 01:45:50 pm
content: HII am reworking my control box of my DIY 3 axis cnc. In various forums I see there can be a problemwith a contactor emitting emi from the coil. My coil is a AC type. I located this Cornell Dubilier Suppression504M02QA100 0.5 UF 100 OHM Snubber Capacitor 200vIts mentioned that the snubber is in parallel with the coil connections. Is this correct.Does this snubber have the correct specs for my contactor.Thanks for your help!

author: Kjelt
author_rank: Super Contributor
timestamp: November 11, 2014, 01:52:40 pm
content: AFAIK a snubber is used across the (switching) contacts to suppress arcing, not the coil.Edit: in the last page of this pdf it is used across the coil, for ac this would make sense, for dc a diode is always enough.http://www.bpesolutions.com/bpemanuals/Snubber.pdf

author: golash
author_rank: Contributor
timestamp: November 11, 2014, 02:04:24 pm
content: HiHere is a thread I used as reference information.http://www.cnczone.com/forums/general-cnc-machine-related-electronics/151824-ac-dc-power-isolation.htmlA person in the forum mentioned the following info: "That appears to be a RC snubber, it is intended to go across the coil terminals, not the power contacts, although there are versions that are intended to be wired across the power conductors but are usually larger capacity."I`m uncertain as to what`s correct.

author: SeanB
author_rank: Super Contributor
timestamp: November 11, 2014, 03:45:25 pm
content: Across the coil it is better to use a MOV of appropriate voltage rating, which will clamp any high voltage spikes to a safer level. The RC snubber will also work, but the MOV does a better voltage. Typically if your coil is a 24VAC one the MOV will be a unit between 24 and 30VAC rated.

author: Seekonk
author_rank: Super Contributor
timestamp: November 11, 2014, 06:45:21 pm
content: I actually used to manufacture snubbers. Use it across the coil. RC will be quieter than a MOV. Most MOVs will allow excessively high voltages.

author: golash
author_rank: Contributor
timestamp: November 11, 2014, 07:24:27 pm
content: Hi SeekonkDo the specs on the snubber seem correct for my setup. The contactor has a AC coil and the total system current is 20 amps.
Snubber circuit required opto-isolated triac? - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: March 28, 2016, 04:57:54 am
content: 1. i have a application in which MCU(+5V) is driving MOC3021 which in turn on/off triac.Load is 100% resistive. I have checked Max load current by plugging it directly to ac, it comes out to be at 322mAac at 248Vac.2. MOC3021 has two application circuit given in its datasheet, one with resistive load which has no snubber ckt & other with inductive load with snubber ckt.3. Since in my case load is entirely resistive, can I go with ckt with no snubber as mentioned in attached ckt.4. Triac used is T1M5F-A.
"Snubberless" triac - Page 1
Forum section: electronics / beginners

author: aneevuser
author_rank: Frequent Contributor
timestamp: April 26, 2022, 11:36:45 am
content: I'm trying to educate myself about SCRs and triacs, starting from pretty much zero a week ago, so this is very much a "noob" question:STM (and maybe others?) make a range of triacs that they call "Snubberless" and I'm having difficulty finding out exactly what this implies. Here are two ideas:1) These devices need no snubber circuit, regardless of load, inductive or not - they simply won't trigger when you don't want them to.2) These devices are rather more immune to spurious dv/dt triggering than non-"Snubberless" devices, but for best results, you'll still need a snubber, but it need not suppress transients quite as harshly as you'd need for the non-"Snubberless" models.3) I'm totally confused and it implies something else altogetherI'm guessing that 2) is the most likely but I'd be happy for someone who knows what they're talking about to comment.

author: wraper
author_rank: Unknown
timestamp: April 26, 2022, 11:51:58 am
content: It's a trademark STM uses for 3 quadrant triacs.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 26, 2022, 09:37:33 pm
content: It's marketing goobledigoop.Customer to manufacturer X:"I want a snubberless triac"Manufacturer X:"I'm sorry but that letter combination is trademarked by company Y and we are legally not allowed to print that on our stuff."In essence, The way I understand it, the gate of a triac has a parasitic capacitance, and when the voltage over a triac changes very quickly, that parasitic capacitance can put enough current through the gate to trigger the triac.So manufacturers have to find some balance between making the gate sensitive enough so it triggers reliably with a small current, and making it not too sensitive to prevent false triggers.

author: aneevuser
author_rank: Frequent Contributor
timestamp: April 30, 2022, 02:44:19 pm
content: Since posting this question, after further research I've found the following app. note on the subject, which seems to be claiming that the 3-quadrant "snubberless" triacs generally need no snubber circuitry, nor dI/dt limiting inductors when used with inductive loads. Sounds a little too good to be true, to my mind.http://datasheet.datasheetarchive.com/originals/distributors/Datasheets-NXP/DSANXP0100024.pdf

author: SeanB
author_rank: Super Contributor
timestamp: April 30, 2022, 03:28:44 pm
content: It is, though they do work well with pure resistive loads, but really you will want a snubber if you are dealing with any load with signifigant inductance, or long leads between the TRIAC and the load.

author: aneevuser
author_rank: Frequent Contributor
timestamp: May 06, 2022, 11:59:08 am
content: Quote from: SeanB on April 30, 2022, 03:28:44 pmThanks. That was what I was assuming. I want to make a hand drill speed control, so I guess that's about as inductive as it gets. I shall plan accordingly.
So how do I use IGBT? - Page 1
Forum section: electronics / beginners

author: technix
author_rank: Super Contributor
timestamp: November 13, 2016, 10:53:41 am
content: I have a few IRG4BC20KD IGBTs I bought with the intention to experiment with, but I had zero idea how to use it. What kind of beginner's experiments can I try with it?I have a 20V supply (a Dell 65W laptop power supply,) level shifters to interface microcontrollers (IR2101 and IR2110) as well as microcontrollers that supports high-seed PWM and dead-time control (STM32F103CB @ 72MHz and ATtiny85 @ 64MHz)

author: bktemp
author_rank: Super Contributor
timestamp: November 13, 2016, 11:16:34 am
content: IGBTs are very similar to MOSFETs. So you can use them like MOSFETs.IGBTs will work at 20V, but at low voltages (<200V) MOSFETs are better, because of the faster switching speed (lower switching losses) and lower voltage drop (lower conduction losses).

author: technix
author_rank: Super Contributor
timestamp: November 13, 2016, 11:50:26 am
content: Quote from: bktemp on November 13, 2016, 11:16:34 amSo I can just use those the same way as MOSFETs? Can I use those in linear region for low-power experiments (I use my IRF540 and IRF4905 in linear region fairly often?)

author: bktemp
author_rank: Super Contributor
timestamp: November 13, 2016, 12:34:18 pm
content: An IGBT is basically a PNP transistor driven by an N-channel MOSFET. So the input behaves like a MOSFET with a slightly higher threshold voltage.IGBTs are designed for switching operation, therefore most datasheets do not have any specifications for linear operation. Manufacturers also do not recommend linear operation.But you can use them for linear operation at low power levels (similar to mosfets, maybe up to 30W for TO220 and 50W or so for TO247 package, depending on the voltage).

author: Cliff Matthews
author_rank: Unknown
timestamp: November 13, 2016, 04:42:40 pm
content: Quote from: bktemp on November 13, 2016, 12:34:18 pmI have 2 IGBT half-bridge modules pulled from a crashed golf-cart, with hopes one day of using them as lone series pass devices.. A spec sheet on a similar 150amp model shows SOA of only 4 amps with Vce of only 50v (that sucks..) Am I reading this right?

author: edpalmer42
author_rank: Super Contributor
timestamp: November 13, 2016, 07:26:18 pm
content: I scavenged a couple of thesehttp://www.ebay.com/itm/181361997908out of a large UPS. Testing has shown that they're IGBTs, but no info is available on them. How can you measure or estimate the ratings of an IGBT?

author: Cliff Matthews
author_rank: Unknown
timestamp: November 13, 2016, 07:46:25 pm
content: Quote from: edpalmer42 on November 13, 2016, 07:26:18 pmTake that sticker off the side.. But guard G1/B1 and G2/B2 pins from static first. ** like this:

author: Cliff Matthews
author_rank: Unknown
timestamp: November 13, 2016, 08:21:47 pm
content: This may help you:http://www.irf.com/product-info/datasheets/data/irfk3d350.pdf** Similar:http://jxfmodules.en.alibaba.com/product/60430037948-800178149/IR_mosfet_transistor_IRFK6J450.html
So I bit off more than I could chew... - Page 1
Forum section: electronics / beginners

author: SteveThing
author_rank: Newbie
timestamp: April 12, 2014, 06:26:16 am
content: I was browsing TI's website and learned about their free samples. So I ordered some stuff... it arrived and I realized very quickly that I could not use any of it. Now I feel like I cheated TI because I do not have the technical know how to use any of it. Big failure on my part to read everything before clicking "order".What I got was this:http://www.ti.com/tool/SAT0027I am just blown away at how small these components are. I mean, WOW! I'd love to use the boost converter and PoE chips, but I do not have the soldering skill or engineering know how yet. Heck, I'm still playing with 555 timers and 3mm LEDs....If anyone wants these parts, feel free to PM me (S&H on you though).

author: David_AVD
author_rank: Super Contributor
timestamp: April 12, 2014, 06:55:58 am
content: Ummm... might be good to know where you're located (for postage costs).

author: nerdyHippy
author_rank: Contributor
timestamp: April 12, 2014, 02:32:18 pm
content: I don't mean to knock you for doing the right thing, but why would a person pay you for free samples rather than getting them for ... free?

author: linux-works
author_rank: Super Contributor
timestamp: April 12, 2014, 03:01:09 pm
content: it seems he's asking shipping costs. handling, I'm not sure I agree with, but shipping costs, sure, that makes sense.

author: nerdyHippy
author_rank: Contributor
timestamp: April 12, 2014, 03:21:16 pm
content: Quote from: linux-works on April 12, 2014, 03:01:09 pmWhy would it make sense to pay a person to ship chips that TI will ship for free?

author: SteveThing
author_rank: Newbie
timestamp: April 12, 2014, 08:53:22 pm
content: I only meant shipping costs. As for why, I don't like to waste things and from what I've read, not all countries can participate in their sample program. If I am wrong, I apologize for wasting people's time.I am located in Seattle Washington.

author: nerdyHippy
author_rank: Contributor
timestamp: April 12, 2014, 10:42:59 pm
content: That's a good point about international samples, I didn't think of that.