hybridfree/eevblog-posts huggingface dataset:
On by default switch - Page 1
Forum section: electronics / projects

author: kuon
author_rank: Regular Contributor
timestamp: August 29, 2019, 07:39:48 am
content: I have a power supply which has an inhibit pin that must either be left floating for the power supply to be on, or pulled down for the power supply to be off.I want the power supply to be off by default when power is applied and be turned on when a control line is pulled high.So basically, when the control line is low, the circuit must conduct, and when the control line is high it must be open circuit and let it float.I would usually use a transistor with a pull up resistor, but the documentation of my power supply clearly state that the inhibit pin must not be pulled up.Do you have recommendation on how to implement this?

author: oPossum
author_rank: Super Contributor
timestamp: August 29, 2019, 08:12:53 am
content: Normally closed (Form B) optocouplerFor example...https://www.mouser.com/datasheet/2/240/CPC1106N-1548424.pdf

author: kuon
author_rank: Regular Contributor
timestamp: August 29, 2019, 07:55:53 pm
content: Thanks, didn't think of the optocoupler approach. Will do perfectly.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 29, 2019, 11:46:53 pm
content: Quote from: kuon on August 29, 2019, 07:39:48 amTransistor without a pullup resistor.

author: David Hess
author_rank: Super Contributor
timestamp: August 30, 2019, 12:56:37 am
content: A p-channel JFET or p-channel depletion mode MOSFET if you can find one will do that.

author: magic
author_rank: Super Contributor
timestamp: August 30, 2019, 05:38:28 am
content: To turn a p-channel JFET off its gate needs to be driven higher than voltage on the inhibit input which is unknown. For an n-channel JFET, negative voltage would be required.A normally-on OptoMOS doesn't seem like such a bad idea in these circumstances.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 30, 2019, 07:12:54 am
content: Perhaps you can also use a resistor. The current source on the pin is probably finite, so you could pull it down.Then you only have to put enough voltage on the chip to turn it on again. With a slight loss in the resistor.
Solved - On composite/CVBS cameras, Can I increase gain beyond factory limit? - Page 1
Forum section: electronics / projects

author: Logan
author_rank: Frequent Contributor
timestamp: January 01, 2022, 02:17:26 pm
content: Hi.If someone have experience on this, have anyone ever try to turn up the max AGC limit on an analog CCTV camera?Some old big cameras do have several internal adjustable trim resisters, but according to service manuals, the closest ones are for AGC reference @ 800mv, still cannot boost gain.It seems most of them are using digital chips for processing, so maybe we cannot change it in a simple way?Thanks.

author: CaptDon
author_rank: Super Contributor
timestamp: January 01, 2022, 03:20:39 pm
content: I spent a lot of time trying to increase gain for low light level applications. The enemy is always noise. Shot noise in the vacuum tubes like vidicons, orthicons and the like. With CCD or CMOS it ends up being clock noise as well as a form of shot noise. The signal to noise ratio just goes to crap when you try to ramp up the gain. The signal to noise ratio of the detector is poor at low light levels and when you amplify trash you just get more trash PLUS the noise of the amplifier. Also when you ramp up the gain you find another problem that many detectors have a limited dynamic range. If you optomize for gain then the highlights overload. If you design to accommodate highlights then you need more scene lighting to eliminate objects in the shadows from disappearing. Logarithmic amplifiers can help and are used in radar video chains where echo strength varies by 100Dbor more, but they create a weird unusable look when processing an NTSC type signal and again you have a detector with small dynamic range between noise floor and overload.

author: Logan
author_rank: Frequent Contributor
timestamp: January 01, 2022, 04:49:28 pm
content: Quote from: CaptDon on January 01, 2022, 03:20:39 pmThank you for replying.But many cameras are not going far enough to even show noise. When they meet lighting conditions they don't like, picture will just black out without giving me chance to consider SNR limit...

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 01, 2022, 08:33:45 pm
content: I suspect it's intentional so that cameras in poor lighting conditions don't trigger image based motion detection. If you can find the datasheets for the image processing chips, it might be possible to hack it to allow it to increase gain as much as needed to get an image even if it ends up noisy.

author: Logan
author_rank: Frequent Contributor
timestamp: February 11, 2022, 04:44:09 pm
content: Quote from: NiHaoMike on January 01, 2022, 08:33:45 pmWell, I couldn't believe this works, on multiple models.It's unbelievable those manufactures don't set there devices to best performance with hardwares already inside.I improved both sensitivity and dynamic range on them, with some jumper wires.

author: Renate
author_rank: Super Contributor
timestamp: February 14, 2022, 07:14:07 pm
content: How about some IR illuminators?
On differential pairs - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: August 21, 2014, 05:07:11 pm
content: It annoys me that there isn't a standard pin configuration so that there's no crossed over pairs when going from one chip to the other.I always suggest that P and N be swapped to keep the layout "clean" and free of vias. Seems to me that signal integrity is more important than some arbitrary convention of what 1 and 0 means, right?Especially as the board complexity grows, every via just chokes the other layers, and when you add the ground transition vias you end up using 8 vias per swap, 2 signal and 2 ground vias on the source side, and the same at the destination.So if it's just fast digital stuff like a clock, why couldn't I swap P and N?If it's a PCIe bus, I believe the standard allows for link training so it figures all this out?But what about a 1GHz differential (100ohm) analog link, like what's in front of a high speed ADC? (or the output of a fast DAC for that matter.)I think it shouldn't matter to swap pairs as long as the rest of the people are aware of it.But I feel I'm missing something crucial here. Is it just convention that prevents swapping?
on my search for stepper motors - Page 1
Forum section: electronics / projects

author: siliconmix
author_rank: Frequent Contributor
timestamp: January 28, 2012, 08:41:38 pm
content: my next project is to build a 3 axis table top size cnc miller.for pcb n stuff.i 'v goto have the motors for free(otherwise i won't get a buzz).took apart a hp desktop 3940 printer hoping to find at least 1 stepper motor.i found 2 dc brushed motors.it has to be easier with a stepper but they went for a cheaper type.fair play to them mind to achieve that accuracy.

author: sonicj
author_rank: Frequent Contributor
timestamp: January 28, 2012, 09:00:36 pm
content: typical of newer inkjet scanner/printers....go to the flea market / thrift shop / junkyard and look for old flatbed scanners & laser printers. if you find any, good chance they will be too small, too big, too crappy, wrong step type, wrong wattage, etc. chances of finding a useable, matched pair is even worse.... personally, i would suck it up and buy a surplus set with the specs you need.now that i think about it, i might have a pair of 24v steppers from a printer that matches your price requirement.... i'll take a look later.-sj

author: Unknown
author_rank: Unknown
timestamp: January 28, 2012, 09:01:42 pm
content: There must be an encoder or a magnetic strip ruler in there to serve as a reference. With this reference the dc motor can be more accurate than the stepper. Don't let it go to the landfill without hacking it first

author: siliconmix
author_rank: Frequent Contributor
timestamp: January 28, 2012, 09:09:32 pm
content: i won't pay for any stepper motors no time.i'll keep up my search for the 3 i need.if you do see a butt sticking out of a skip(dumpster) dont beep your horn.i've banged my head loads of times from that.yes hal there was an encoder on there and it did look interesting besides it's flimsy appearance.3 the same or hang my head in shame...meh

author: Freighternut
author_rank: Regular Contributor
timestamp: January 29, 2012, 09:56:31 pm
content: Check your local Photocopier dealer. They are often scrapping trade in machines and I find they are a great source for steppers.However not all models copiers use steppers.

author: siliconmix
author_rank: Frequent Contributor
timestamp: January 30, 2012, 06:57:45 am
content: thanks mate i just stripped an old one and there where two in there but different specs.i'll try and find my local place if i have one.
ON-off circuit almost works - Page 1
Forum section: electronics / projects

author: gregfox151@gmail.com
author_rank: Contributor
timestamp: February 09, 2014, 06:48:36 pm
content: Hello all, I would love some help on a problem I uncounted. The circuit attached is a on – off circuit with low battery cut off and reverse voltage protection. It works just great, that is, almost up to my design voltage of 16.5V.The circuit is designed to allow a rechargeable 14.8V battery (16.8V fully charged) to power a circuit. The circuit only draws 1 or 2 uA and can be powered (almost) forever. If the voltage gets too low the battery could get damaged, thus the low battery turn off, set by Q1,R4,R5 and d3If turned on at below 13.3 volts, it will stay on up to the input of 16.5 volts. However if the voltage is set at 16.5 volts LED D4 will only flash on and then go out. In other words it will not stay on.The 4013 is rated up to 18V, and I turned down R36 to minimum (towards GND) in an attempt to eliminate it from the circuit. I also bypassed Q2 to eliminate it.Can anyone explain why it will only turn on up to 13.5V?Thanks!Forgot the 4013 is a MC14013BDTR2G

author: dannyf
author_rank: Super Contributor
timestamp: February 09, 2014, 06:57:41 pm
content: Just a suggestion for the reverse polarity circuit: check out an application note from IRF. It can be done with either n- or p-channel mosfets alone, no resistors or zeners. And it is quite efficient - once on, it has only Rds in the circuit (less of a concern here).As for the rest of your circuit, they seem to be too complicated for what you are trying to do. You should be able to get it done with comparators or a mcu.

author: gregfox151@gmail.com
author_rank: Contributor
timestamp: February 09, 2014, 07:05:56 pm
content: Thanks I'll take a look. The circuit is really quite simple and works really well except for that pesky 16V.
On Semi: EMI2121 USB Filter Pinout - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: October 18, 2016, 08:19:48 pm
content: Does anyone here have experience with the On Semi EMI2121 EMI/ESD chip?http://www.onsemi.com/pub_link/Collateral/EMI2121MT-D.PDFI'm attempting to keep my USB circuit as compact as possible and I noticed that the positive and negative pins on the input of the chip do not line up with the actual data lines on a USB connector. IN_1+ and IN_1- should be switched.USB Connector pinout:https://en.wikipedia.org/wiki/USB#PinoutsIf the simplified schematic can be believed then having USB_DM connected to IN_1+ and USB_DP connected to IN_1- shouldn't matter. I just wanted to get some

author: exmadscientist
author_rank: Frequent Contributor
timestamp: October 19, 2016, 03:14:59 am
content: I haven't used that particular part, but a similar ST part (ECMF02-4CMX8) has the same pinout issue and swapping the pairs works just fine.Just be sure to swap them an even number of times!

author: technix
author_rank: Super Contributor
timestamp: October 20, 2016, 04:28:33 am
content: As far as I see the two channels are completely symmetric and can be interchanged freely.

author: Pack34
author_rank: Frequent Contributor
timestamp: November 22, 2016, 02:46:12 pm
content: I never mentioned the resolution for this. Swapping the pins worked out fine. I was concerned since the channels were specifically labeled as Data_Plus and Data_Minus but it didn't matter.
ON Semiconductors’ NCP4632 LDO? any thoughts? - Page 1
Forum section: electronics / projects

author: cmmnml
author_rank: Newbie
timestamp: October 12, 2015, 01:39:36 pm
content: I was looking for a relatively cheap, easy to use LDO to be used as a post SMPS regulator. The Buck converter generates the 5V rail and the LDO is intended to generate 3.3V from the 5V input. Based on my requirements given below, my parametric search gave me couple of choices. Out of those, the NCP4632 LDO from ON Semiconductor seems to be quite attractive part.www.onsemi.com/pub/Collateral/NCP4632-D.PDFThe features of NCP46321. 3A max current2. 510 mV max drop-out voltage3. 1% accuracy4. Price of $1.64 (100 units)5. ~35 dB PSSR at 700 kHz (which is the switching frequency of SMPS)6. Load transient +/- 50mV with 10 uF output capacitor7. Soft-startHas anyone used this part? Or any better recommendation?My requirements are1. 3A max current2. Vin – 5V, Vout – 3.3V3. 1 – 2 % accuracy4. Price about $1.5 – $2.5 (100 units)5. Good PSSR at 700 kHz (~35 dB or better)6. Good transient response ( +/- 50 to 100 mV)Other parts (with similar price) came through the parametric search are,1. Texas Instruments LP38501 - $1.67 (100 units) -> Accuracy is only 3.5% (at 25C)2. Texas Instruments LM1085 - $1.65 (100 units) -> Good old part, but poor PSSR at 700 kHzOther parts (expensive)1. TPS74401 - $4.91 (100 units) -> Very nice part, 1% accuracy, ~50 dB PSSR. But EXPENSIVE!2. TPS74901 - $3.22 (100 units) -> In the same family of TPS74401, but transient response is not good.3. There are many other good parts from Liner Technology. But LT parts seems to be very expensive.Appreciate any thoughts? Suggestions?
One Cycle Control vs current mode control - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: November 06, 2024, 10:56:50 pm
content: Keyue Ma Smedley is well known in her circles for inventing the concept of one cycle control. It basically works like this: If, for example, you have a buck regulator, put an integrator that is driven from the switching stage raw output. Begin the integration at the start of the switching cycle and terminate the switching cycle when the integrator output reaches a reference level corresponding to the desired output voltage. Then reset the integrator ready for the next cycle. It is said to have very fast response time when maintaining a desired DC output.So far so good. But then it struck me - this doesn't seem all that different to current mode control. Instead of having an integrator you either directly or indirectly sense the inductor current and terminate the switching cycle when the inductor current reaches a reference value. So then, what's the big deal about OCC by comparison?https://ieeexplore.ieee.org/abstract/document/471281https://www.researchgate.net/figure/One-cycle-control-schematic_fig2_277333522

author: xavier60
author_rank: Super Contributor
timestamp: November 06, 2024, 11:34:33 pm
content: I first saw an idea like that with the TDA4601 and TDA4605 controllers. Switching transistor current is simulated by a capacitor being charged via a resistor from the HVDC while the transistor is on and fully discharged when the transistor is off. The controllers operated in transition mode, never CCM.I guess the idea is to avoid the need for a CS resistor which would be great advantage in high current designs.

author: David Hess
author_rank: Super Contributor
timestamp: November 07, 2024, 12:51:02 am
content: It reminds me of slope compensation when used with constant off-time and current mode control.
One-FET level convertor (how did it work?) - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: October 11, 2019, 08:40:58 am
content: I recall seeing a very simple 3/5V level convertor which used 1 MOSFET and little else in an Elektor schematic. I think it was bi-directional also.I can't quite remember the details though.

author: mikerj
author_rank: Super Contributor
timestamp: October 11, 2019, 08:49:27 am
content: The design was published many years back by Philips for use in mixed voltage I2C buses,this documentdescribes the operation. It's only suitable for an open collector/drain bus.

author: 741
author_rank: Frequent Contributor
timestamp: October 11, 2019, 08:55:26 am
content: Wow, that was a fast response; many thanks indeed.
one milligram weight scale from 1962 teardown - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: October 20, 2022, 08:34:18 am
content: this is a really crasy weight scale, its range go from 1 milligram to 200 milligram, YES this thing is overloaded at 0.2 Gram !! it had terrible battery leak, and a broken overloaded balance coil, see here how i tried to fix it.https://youtu.be/dwMl0CTE5j4
One more question about Exar XR2206 - Page 1
Forum section: electronics / projects

author: dimani4
author_rank: Contributor
timestamp: March 11, 2023, 02:12:55 pm
content: Hi people.I need to buy couple of oscillators of XR2206 and I'm completely lost because on ebay I found so much offers of that amp. They all claimed it's genuine and new. I dont exclude an option it's really could be genuine but there are so much counterfeit and this oscillator already discontinued since 2017. So maybe you know some trusted source to buy from ebay? maybe you had some good experience and you bought really genuine product from one of the sellers?I found some offer with price similar to Jameco prices (https://www.jameco.com/z/XR2206CP-EXAR-Corporation-IC-XR2206CP-Monolithic-Function-Generator_34972.html?CID=MERCH):https://www.ebay.com/itm/182493882203?hash=item2a7d7ba75b:g:zS4AAOSw4CFYzQtr&amdata=enc%3AAQAHAAAA8AD2QJhDKwFGoXHqIyAfMNvFPzo%2BU6Tm3rsF2DvBne%2Brs%2BMppQ2Nhu0rOxrMj93RF3tGs0jXtzyIseVEKvdh%2FauXW1%2Bu7qXCljJkmKRuZR2TzMC8au79DJpeN4voR6CBIEcBdxt0pYAqyFiTSuC39UyuvyGNx6RnBf%2F8VLm4qETeuDHnluk%2BtixTbA0dpsVf4zVrECebKSNKaC0YIn9jVN%2F1f2vkJ87Z0U7QLLny9x2C8mVKw1YaRP6g51ynRJdFgr5zlCr3JK8zm5K4aSHeLqt2L8zQ5YhFGVJlVMio9HXjbQqKeu6q0Z%2BvttZVJzjG%2BQ%3D%3D%7Ctkp%3ABFBMyOW5i9phThey claim it's new. I try to find some information about series 9622 but didnt find anything. It says in description it's produced in Thailand. May I trust it?Thank you very much.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 11, 2023, 02:18:46 pm
content: thread herehttps://www.eevblog.com/forum/dodgy-technology/dont-buy-any-kit-with-xr2206-wfg/hum i would say it could be fake BUT i dont know when they have ceassed production, if you see tons of them with the same date code i would have doubtsFor the 2206 or 8038 i have they are in the 86 87 year ranges, some say it ended around 91but some EXAR datasheets about them are 2008 ??

author: dimani4
author_rank: Contributor
timestamp: March 11, 2023, 03:27:04 pm
content: Thank you for your answer.About buying thing. I would say buy it but configure it: there are lot of videos about that:For such a money you get good generator: you cannot work in the full range as original chip (10-26V) but at low voltages it works fine, depends on your needs.What do you think about that company Jameco? looks like legit?I guess they ceased to produce them later than 1991 because MaxLinear ended to produce them as they bought Exar only in 2017 (according wikipedia).Thanks.
One more solder fume extractor - Page 1
Forum section: electronics / projects

author: babysitter
author_rank: Frequent Contributor
timestamp: March 21, 2015, 08:25:14 am
content: I also want to get rid of the soldering fumes without reducing solder consumption, too.A lateral channel blower that I used to quick-start barbeque fires now has settled under my bench, with tubing intended for vacuum cleaner guiding most fumes away from my nose and out of the window.PicturesThe main components are the blower hanging under my desk, big tubing leading out of the window, a small (not yet connected) garden hose leading to the solder iron stand und a big nozzle mounted on a desk lamp stand from scrapheap.Zipties connect the garden hose to the stand. A hood is still required to direct fumes to the sucker. Was the last idea for addition, still missing a Tee to connect to the low pressure side of the blower.The scrap desk lamp stand was modified with some heavy iron plates glued in the hollow foot to prevent tipping. The wastewater piping tee will be replaced by a rounded elbow for more laminar flow and smaller size. Also, I will look out for one of those "vuvuzela" horns that german soccer fans like so much as inlet nozzle. I figure it might work better than this.The main engine. Candidate for noise reduction!The last hose can go outside thru the partly-open window.Even when I intend to blow to the outside, I want to set up a filter box for activated charcoal and maybe a second HEPA stage.

author: SeanB
author_rank: Super Contributor
timestamp: March 21, 2015, 08:38:02 am
content: Silencing a side channel pump is hard, they are very noisy, and very little, aside from a tuned length stub on inlet and outlet, will help. Simplest filter is to go to the auto parts store and look for a car air inlet filter, or the scrapyard and get one complete for eg Volkswagen golf/seat/audi/skoda that has an inlet pipe, a box with the flat filter unit in it and an exhaust pipe. Then you place one on the inlet and the exhaust near the pump, which will reduce the noise.With a larger one that was used on a koi pond the simplest solution was a large Donaldson air filter unit, intended for a ERF truck engine, placed on the inlet side, complete with the primary and secondary filter units, drain valve and clogging indicator. When it finally clogged up with dirt it was easy to tell from the very loud whine from the pump sucking down to 0.3bar
one of them days.. where all is difficult, video, sparks and stuff.. - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 17, 2022, 10:10:43 pm
content: 15 sec videotodays troubles :https://youtu.be/3s1_pHp0vxg

author: rsjsouza
author_rank: Super Contributor
timestamp: July 17, 2022, 10:25:37 pm
content: We've all been there... It will pass.Two Fridays ago I was slated to do an antenna matching on three boards, which involves constantly removing/soldering various 0201 passives and doing measurements on a VNA at each iteration. Something that should have taken about 1-1/2 hour, took me three hours with two boards missing parts and a third one with a ripped track (progress: 0%). Fortunately I was able to resume successfully on Monday with a very cold head.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 18, 2022, 01:55:19 am
content: Quote from: rsjsouza on July 17, 2022, 10:25:37 pmYep, like pushing capacitors about that size around on RF amplifier boards with toothpicks, while watching their swept frequency response.I would just get one in the right spot & it would slip out from under the toothpick, mostly disappearing down into the guts of the transmitter, where there was some hope of retrieval, but sometimes flipping high enough to land on the floor.Even grovelling on the floor didn't find them, then.The worst thing was that I thought I had left that sort of thing behind back in the early 1980s, when I worked in a (far better equipped) place where we tuned a lot of solid state PAs."Yes, Virginia, they had surface mount capacitors in the 1980s---we used to call'em 'chip capacitors'! "

author: rsjsouza
author_rank: Super Contributor
timestamp: July 18, 2022, 11:26:46 am
content: Quote from: vk6zgo on July 18, 2022, 01:55:19 amIndeed the darn things tend to get statically attracted to the most incredible things and can jump like fleas, especially when being removed form the cut tape. Another problem is that when two parts fall into the transmitter but you couldn't locate the first. When the second falls, you can never tell which one is which anymore. That is another issue I have here as well - when I forget to sweep the bench before working, I can't even use the parts that fall in the table as they might be from someone else's project (the soldering stations are shared).
One shot adjustable ramp generator - Page 1
Forum section: electronics / projects

author: zero0d
author_rank: Contributor
timestamp: June 06, 2022, 08:25:39 pm
content: Hi all,please can you suggest a circuit to implement following:- at trigger impulse i need to generate a ramp from 400mV to 8V with adjustable ramp time.i will need a potentiometer to adjust the time of the ramp. eg i set to 10ms, meaning the ramp must go from 400mV to 8V in 10ms.Is this possible to do without a MCU?Br.

author: TimFox
author_rank: Super Contributor
timestamp: June 06, 2022, 10:16:03 pm
content: This is essentially a triggered CRO (not DSO) horizontal ramp generator.It can be implemented with a 555 and a current source to get a linear ramp waveform on the capacitor.You may need another op amp to get your end point voltages correct.Fig 9 on page 10 of the data sheethttps://www.ti.com/lit/ds/symlink/ne555.pdfshows the basic monostable multivibrator circuit.With a resistor "RA" charging the capacitor, you do not get a linear ramp.If you replace RA with a suitable current source, the ramp will be linear between the thresholds of the 555.As drawn, the capacitor will be discharged after the end of the ramp, and will not charge again until the next trigger pulse.The classic reference for time-base circuits is O. S. Puckle "Time Bases (Scanning generators)", John Wiley & Sons Inc. 1951

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 09, 2022, 05:33:38 pm
content: Using a current source to charge a capacitor is the classic way to get a linear ramp, and discharging the capacitor regularly makes it into an oscillator.Another way is to build an integrator with an opamp resistor and capacitor, and let it integrate a constant voltage.There is always some limit in the speed in which a capacitor can be discharged. (Zero time would take infinite current).A possibility is to design a triangle oscillator from an integrator, and at the moment you switch the reference, you also swich the output between "normal" and "inverted". This may lead to some assymetry between the even and odd periods.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 09, 2022, 05:44:23 pm
content: So yeah, the typical analog approach would be an adjustable current source charging a capacitor, followed by a buffer.
One uSD card accessed in high speed by two micros (in producer-consumer setup) - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: March 02, 2021, 09:13:08 pm
content: Hi,I need to setup a uSD for "as fast as possible" data transfer in a producer-consumer configuration (i.e. one micro continually writes data from sensors into the uSD and another micro reads it continually).Any suggestions for a solution that allows as fast as possible data transfer for both micros and fully sync the two operations?Obviously I can provide one or two handshake lines between the micros that signal each other to sync the access tot he micro but I was wondering if there are other/better solutions, perhaps some IC which also contain some input and output buffer to allow writes by one micro while the other is reading? I could not find any ICs that do that but maybe there are?Thank you

author: mon2
author_rank: Frequent Contributor
timestamp: March 02, 2021, 10:56:47 pm
content: Do you need to save the sensor data? The uSD will be a bottle neck I would think. There is FRAM or similar technology that allows for WRITES of data to a non-volatile memory device at high data rates and will outlast uSD write cycles.If you do not need to save the sensor data - you can increase the READ and TRANSFER to the remote micro. High speed SPI bus?https://www.ti.com/lit/wp/slat151/slat151.pdf?ts=1614673643376

author: ricko_uk
author_rank: Super Contributor
timestamp: March 02, 2021, 11:45:27 pm
content: Thank you Mon2.Yes need to save the sensor data and be able to remove the saved data for reading from a PC (hence the uSD card).

author: ajb
author_rank: Super Contributor
timestamp: March 03, 2021, 01:35:00 am
content: "as fast as possible" isn't a particularly useful design criteria. What's the data rate you're dealing with?What's the reason for wanting to use the SD card for handing data between the two MCUs? Could you not have a different communication channel between the two devices, and only have one of them handle writing? You're going to have a bit of overhead to open/close files for writing/reading every time, assuming you're using a file system on the SD card. If you're doing two MCUs for performance reasons, you could probably move to a higher power part and just use one of them which would make it all a lot easier--since you're talking about having both parts connected to one SD card you are presumable not using two MCUs because you need processing at two physically separate locations.
One/two transistor transmitters - Page 1
Forum section: electronics / projects

author: tree
author_rank: Regular Contributor
timestamp: August 04, 2014, 09:29:36 pm
content: I've seen many circuits using one to two transistors as simple transmitters made of an audio pre-amp and an RF amp. Usually the RF amp has an LC resonant circuit at the collector, which is also where the antenna is connected. These are classified as FM transmitters, but I thought they were AM transmitters since varying the voltage at the base changes the current through the transistor thus changing the voltage at the collector. The only way I can see that it is an FM transmitter is by varying the C-E reverse biased diode junction capacitance which effectively changes the resonant frequency of the LC circuit, hence FM. Which is actually the correct explanation?Here's an example of such a circuit:http://dmohankumar.files.wordpress.com/2011/04/fm-transmitter1.jpgAlso, what's the point of C3?Thanks!

author: w2aew
author_rank: Super Contributor
timestamp: August 05, 2014, 12:20:06 am
content: C3 provides the feedback that causes the transistor to oscillate at the carrier frequency.In these very simple transmitters, the carrier gets modulated both ways (FM as well as a little AM). FM is caused as you suspected, due in part to the change in the transistor's junction capacitance.

author: tree
author_rank: Regular Contributor
timestamp: August 05, 2014, 12:26:25 am
content: Quote from: w2aew on August 05, 2014, 12:20:06 amSo an increase in current through C3 causes a larger voltage at the emitter, thus reducing Vbe, which effectively reduces collector current?

author: Richard Head
author_rank: Frequent Contributor
timestamp: August 05, 2014, 05:41:12 am
content: The circuit is configured in common base (for RF).Very crude circuit.
Online course Hardware Disign - Page 1
Forum section: electronics / projects

author: derZockerMP
author_rank: Regular Contributor
timestamp: July 18, 2024, 11:07:15 am
content: Hello,today i found this online course.https://fedevel.com/courses/mixed-signal-hardware-design-with-kicadDid anyone had made this course and is it worth buying?Especially it cost $100.I came to it throug the youtuber PhilsLab

author: BadeBhaiya
author_rank: Regular Contributor
timestamp: July 19, 2024, 08:37:36 am
content: I haven't bought the course but by just going through the contents, it seems to me it will be only useful if you already have a background in EE but are very new to any kind of actual work (aka new grad who hasn't built many projects)Everything in the course can be learned for free by building projects or even watching videos on YouTube. I guess the real value is in getting the practical information and tips to get started quickly.If I were a beginner I would build projects instead. But that's just me

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 19, 2024, 03:30:29 pm
content: You can have a start by looking at some of the video's from thePhil's Labyoutube channel. Apparently that is part of the same fedevel company. If you like the content / style and want more, then paying for the course might be worth it.It's hard these days to make money with courses. There is so much stuff freely available that a course has to be good, thorough and compact to be worth it.One of the "must watch" video's is the two hour long talk about GND planes by Rick Hartley. It's worth watching all 2 hours and 19 minutes at least twice (with a few months in between).
Online/double-conversion ups delay time?  - Page 1
Forum section: electronics / projects

author: Daniel_Reyes
author_rank: Regular Contributor
timestamp: September 16, 2015, 02:15:33 pm
content: Is an Online/double-conversion UPS truly instant? Any microsecond or nanosecond delay?Sent from my SM-G900P using Tapatalk

author: Chris C
author_rank: Frequent Contributor
timestamp: September 16, 2015, 02:19:04 pm
content: Double conversion is always running from the battery, simultaneously charging it when AC is available. Unless they've taken some improper shortcut, there should be no delay whatsoever.

author: wraper
author_rank: Unknown
timestamp: September 16, 2015, 02:20:42 pm
content: What do you mean by instant? Since it is double conversion, the load is never powered from the mains but from internal voltage, and even can be of different frequency if particular model allows to set this. Load is never switched between internal/external voltage sources.

author: Daniel_Reyes
author_rank: Regular Contributor
timestamp: September 16, 2015, 02:39:51 pm
content: Do you think there could be a delay on the output sense so that the UPS does not latch and store a line fault in its memory? Just hypothesizing here.Sent from my SM-G900P using Tapatalk

author: Magicmushroom666
author_rank: Contributor
timestamp: September 16, 2015, 03:47:08 pm
content: A line fault (ie on the supply) would have nothing to do with the UPS output, as others have mentioned, the input is converted to DC internally before going back to AC. The output is always on and doesn't switch between anything.The UPS i've worked with dont always report faults if they are very quick, but again this has no affect on the output.

author: Daniel_Reyes
author_rank: Regular Contributor
timestamp: September 16, 2015, 03:54:16 pm
content: Understood. Thanks for the help everyone.Sent from my SM-G900P using Tapatalk
Only One Component Remote Controlled latching Led Switch !  - Page 1
Forum section: electronics / projects

author: Kedar264
author_rank: Regular Contributor
timestamp: September 21, 2016, 09:33:58 am
content: Yeah only one component based remote controlled switch !Here's The Videohttps://youtu.be/qPaGx02x1cwThis Very Simple Do It Yourself Circuit Is Very Cheap And Easy To Make , It's looks really cool how it led works . The Photo diode is connected in series with an LED and placed in front of each other When a button on a remote is pressed infrared light from remote decreases photo-diode resistance and thereby LED glows and keeps on latched until you break light between photodiode and led Cool !This Circuit Latches based on its own optical feedback , a transparant photodiode is connected in series with white led ,but there are few catches only works in low or medium light environments ,if you have any improvements please let me know !

author: bobaruni
author_rank: Regular Contributor
timestamp: September 21, 2016, 09:56:55 am
content: That's novel, although I would like to see a resistor in there to limit the current.

author: Kedar264
author_rank: Regular Contributor
timestamp: September 21, 2016, 10:00:07 am
content: Quote from: bobaruni on September 21, 2016, 09:56:55 amActually Photodiode itself acts as a currunt limiting ressistor here at full light its ressistance is about 1.5k ohm .

author: bobaruni
author_rank: Regular Contributor
timestamp: September 21, 2016, 10:11:43 am
content: QuoteThen It's even better than I thought

author: CM800
author_rank: Frequent Contributor
timestamp: September 21, 2016, 10:25:43 am
content: Fun little concept actually. Pity you can't turn it off with the remote....

author: Kedar264
author_rank: Regular Contributor
timestamp: September 21, 2016, 10:42:41 am
content: Quote from: CM800 on September 21, 2016, 10:25:43 amDo you have any solution ?
Only use for MIC signal  - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: June 08, 2017, 06:18:52 am
content: Hello,I want to remove Headphone part from the application circuit of PCM2912,http://www.ti.com/lit/ds/symlink/pcm2912a.pdf.Datasheet says, need to activate pin 26 Vccp that is analog power supply for PLL.Take a look the schematic and suggest me what to do for modification. Can it be possible to use only for MIC?

author: danadak
author_rank: Super Contributor
timestamp: June 08, 2017, 01:29:28 pm
content: Datasheet is a little thin, I would just eliminate the components attached to pins 18 - 22and try on breadboard.Regards, Dana.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: June 09, 2017, 02:25:17 am
content: Dear Sir Dana,I appreciate your suggestion. The reason I am confused is, does PCM2912 works independently for MIC and Headphone ?Take a look in the logic control diagram, it has cross connection between ADC and DAC, while USB protocol processed the signal.

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: June 09, 2017, 04:49:15 am
content: QuoteThe endpoint assignment does not handle Headphone output? Did you see control flow of this algorithm ? ISO-OUT does not contain the information from ISO-IN?

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: June 09, 2017, 05:49:33 am
content: QuoteIf it happen then I could be lucky ! This seems to just using for cheeking sound level form MIC ( as kit manual says).Dont you think that VCOM2 should not be connected as it provided for the center voltage of the headphone amplifier!

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: June 09, 2017, 06:52:05 am
content: Let me test its EVM board it first,Do you think, this USB I /O could applicable for VL812 hub?

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: June 09, 2017, 07:29:11 am
content: Because, we want to add both vedio and audio signal in a hub.
On/Off latch not fully working? - Page 1
Forum section: electronics / projects

author: GamerAndds
author_rank: Regular Contributor
timestamp: January 07, 2014, 04:58:11 am
content: This on off latch for my model railroad is not 100%, I have added the cap which increased its reliability but it still sometimes dosent latch or go off? The light is temp, will be eventually be replaced with a motor and reversing switch.

author: Jibby
author_rank: Contributor
timestamp: January 08, 2014, 10:02:19 am
content: Q1 and Q2 in the circuit function like an SCR. So simply use an SCR. As regards lamp to be replaced by motor is not feasible as the emitter resistance of 1k would provide too little output voltage.

author: GamerAndds
author_rank: Regular Contributor
timestamp: January 08, 2014, 03:09:37 pm
content: Sorry, the motor wouldn't go through the 1k resistor, instead it would go through something like an H-bridge or an op-amp, to be able to control the direction aswel. I was looking for a latch on/off combination but ill just use Dave's version.
On/Off Soft Latching Switch with uC Operating at 3V3 - Page 1
Forum section: electronics / projects

author: beeboopbeep
author_rank: Contributor
timestamp: August 23, 2017, 03:17:44 pm
content: Hi everyone,I wanted to share my schematic for on/off soft latching switch used with a uC where the button also serves as an input to the uC and the circuit can be shutoff by the uC:Datasheets:DMG9933USD (dual PMOS):https://www.diodes.com/assets/Datasheets/ds32085.pdfPMV16XNR (single NMOS):https://assets.nexperia.com/documents/data-sheet/PMV16XN.pdfRS1GTR (diode):http://www.smc-diodes.com/propdf/RS1A-M%20N0988%20REV.A.pdfAs you can see, the power comes from a battery source (~3 to 4.3 V) and the PMOS that controls the power signal will only turn on once the switch button is pushed and the gate of the PMOS (G1) gets grounded. Once the PMOS gate is grounded (or, almost grounded to ~0.6 V due to the diode), the circuit will turn on which will also turn on the DC-DC down converter/buck booster (not shown here) which provides constant 3.3 V. Note that this IC is a single package with both down conversion and boosting capabilities. Since the 3.3 V is now provided for the circuit, the NMOS is turned on and latches the PMOS gate (G1) to ground.Furthermore, I wanted the button to have multi functioning purpose so the power switch button can also act as an input to the uC. Since the battery power source can go up to 4.3 V, I used another PMOS to provide HIGH/LOW signal to the uC instead of providing HIGH/LOW signal in the same level as the battery because the uC operates at 3.3 V. This is also the reason why the gate of the NMOS is pulled high using 3.3 V instead of battery voltage level since this route has to go to the uC to allow the uC to turn off the circuit whenever required.The schematic design first started with Dave's video about the simplest soft latching switch () and I became interested in incorporating into my next design with a uC. I browsed around and found this schematic:http://www.instructables.com/id/Soft-Latch-Power-Switch-Ardweeny/.The schematic from Instructables had an extra diode I didn't think was needed and I made changes from using through-hole components to SMD. I also made other changes so that I can use it with a 3.3 V uC.Any feedback regarding the design would be appreciated!
On/Off switch required ? - Page 1
Forum section: electronics / projects

author: Jan Audio
author_rank: Frequent Contributor
timestamp: April 22, 2020, 01:54:34 pm
content: Hi, i make my projects without on off button normally, is it bad for capacitors ?The capacitor loses - connection while still being full when pulling the powersupply.Does it affect the lifespan of capacitors ?Maybe i need to add power button for my next project.thanks

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 22, 2020, 03:21:57 pm
content: Sorry, it's almost totally unclear what do you mean. You don't want to turn off power switch?Electrolytic capacitors age with time and age with work and age a lot with heavy work.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: April 22, 2020, 04:03:09 pm
content: When powering down i remove the power supply, is it bad for the elkos ?Or do i need a on/off button that makes sure the ground stays connected while the elko is still full ?

author: Cubdriver
author_rank: Unknown
timestamp: April 23, 2020, 07:24:56 am
content: Still not quite following you. By 'remove the power supply' do you mean like unplugging or disconnecting the AC mains cable feeding the power supply built into the device, or are you talking about removing power from a device that's fed by a mains powered DC supply (like a wall wart or brick) by unplugging the DC feed from that power supply o the project?Where are the electrolytics you're concerned about - in the project that's been disconnected from the D.C. power source, or in the output of the D.C. power source that you're disconnecting?-Pat

author: Jan Audio
author_rank: Frequent Contributor
timestamp: April 23, 2020, 01:20:20 pm
content: I learned that the higher voltage on the cap always should be on the + else it is bad and you have to replace the cap.If the cap is still full and both + and - are disconnedted, how does the cap know it is higher then the - ?How can i explain ?

author: squarefrustration
author_rank: Newbie
timestamp: April 23, 2020, 02:06:40 pm
content: Quote from: Jan Audio on April 23, 2020, 01:20:20 pmA capacitor holds charge. The polarity of that charge is determined by the circuit that it is placed in. If you remove the power input to your circuit, the capacitor willnotbecome "confused". The charge polarity will remain the same as it was the moment power was disconnected, and it will discharge to zero at a rate determined by the load it is attached to (as well as it's own leakage). Think of it like a battery. When you have a battery that is not in a circuit, it does not need to "know" which side is positive or negative. Conversely, many devices do not have an on/off switch, such as power supply "bricks" for laptops and phones. When you unplug these devices, the DC filter capacitors drain through the circuit that is loading them. Hope that helps!
Onsemi restarted production of FDD4141 P-MOSFET? - Page 1
Forum section: electronics / projects

author: hanakp
author_rank: Regular Contributor
timestamp: May 05, 2024, 08:12:07 am
content: One product I designed used FDD4141 P-MOSFET from Onsemi, but it got EOL notification in 2022:https://www.onsemi.com/pcn/public/final-document/h9R-2M6KBXfyYbXss5nFZAIt was listed as Last Time Buy on Onsemi website about a year ago:https://web.archive.org/web/20230322130657/https://www.onsemi.com/products/discrete-power-modules/mosfets/FDD4141But today I noticed the transistor is back in Active status:https://www.onsemi.com/products/discrete-power-modules/mosfets/FDD4141Big e-shops like Mouser and Digikey list it as Active too, Farnell says it's EOL, but has many thousand fresh units in stock. Of course, I found several suitable replacements back then, so I'm just curious: how often semiconductor companies restart production of a component? I've never heard of that before. Or maybe the Active status on Onsemi's website is just a mistake?

author: aldi
author_rank: Contributor
timestamp: May 05, 2024, 02:37:57 pm
content: https://www.onsemi.com/PowerSolutions/pcnPub.do?pn=FDD4141There is a "Product reactivation notice" there.

author: hanakp
author_rank: Regular Contributor
timestamp: May 05, 2024, 04:39:49 pm
content: "Reactivated product." You learn something new every day. How long usually such "reactivated" semiconductors last?
Oops I did it again Opto CTR - Page 1
Forum section: electronics / projects

author: w3amd
author_rank: Regular Contributor
timestamp: January 21, 2016, 03:19:37 am
content: Hi guys,I have a board prototype we went to an outside Eng house to help us with but in my specification I didn't call out the current drive required from the opto Collector-Emitter.I have one option of re-working the board and placing in a darlington. We have 1mA drive and need 10mA out (it drives a Cryodon SSR(s)).I'm trying to think of ways to rework this without re-working the PCB (there might be about 100 wires which would need to be removed). I was thinking about placing an external large package transistor which would be easy to work with or some other package to work with and create the darlington I need outside the PCB.Then, I thought of seeking help here and maybe someone has a great idea. I can expect about 0.8mA output from the PCB C-E opto. I think I could get by with 8 which would be 800% more than I have now. 24V drive Is there another way to do this easily?TIAJohn

author: SL4P
author_rank: Super Contributor
timestamp: January 21, 2016, 07:05:00 am
content: how about a small relevant segment of the schematic, and PCB as photos ?Maybes we can suggest a way out for you!