hybridfree/eevblog-posts huggingface dataset:
Need help to calc the needed cap for a generator - Page 1
Forum section: electronics / projects

author: Chriss
author_rank: Frequent Contributor
timestamp: August 26, 2023, 09:20:05 pm
content: Hi!I need to attach 3 caps to a 3 phase generator and for these purpose I need to calculate the capacity for each one.The caps are connected in delta.The parameters are:Reactive Power = 8.125 KVALine Voltage ( between 2 phase ) = 510VFrequency = 50HzPower Factor = 0.8What formula can I use to calculate the cap's correct value?I using this formula but Im not sure if it is correct:I have some feeling the capacity is to high calculated. Something I'm missing...Required Capacitance (per phase) = (Reactive Power × 1000) / (Line Voltage^2 × Frequency × Power Factor)The result for each cap is: 780uFIs this a correct?Thank you for helping.My best regards.Chris

author: Konkedout
author_rank: Frequent Contributor
timestamp: August 27, 2023, 03:18:52 am
content: Been a long time since I did anything like this. The easy way would be spice simulation. (??)
Need help to identify a strange connector - Page 1
Forum section: electronics / projects

author: Pinkus
author_rank: Frequent Contributor
timestamp: October 24, 2020, 12:58:39 pm
content: Hello EEV folks - I am asking for some help.I do have this (probably broken) connector from a friends device. Somebody else did try to fix it, but this was not for long.I never saw this connector before in my live. Before I now possibly destroy this connector, does anybody recognise this connector (company, type)?Thanks in advance for your help!

author: tooki
author_rank: Super Contributor
timestamp: October 24, 2020, 02:52:27 pm
content: Looks like Binder series 719.

author: Pinkus
author_rank: Frequent Contributor
timestamp: October 24, 2020, 03:57:14 pm
content: Yes it is. THANK YOU tooki

author: tooki
author_rank: Super Contributor
timestamp: October 24, 2020, 04:08:54 pm
content: You're welcome! I thought it looked like something I'd seen in a catalog, and I was able to find it quickly, by good fortune!
Need help to identify diode - Page 1
Forum section: electronics / projects

author: ksb
author_rank: Contributor
timestamp: September 16, 2018, 02:29:08 pm
content: Friends,Can someone suggest me the replacement part for diode below. The marking code is T1 J8H.

author: Benta
author_rank: Super Contributor
timestamp: September 16, 2018, 03:27:04 pm
content: Looks like a Vishay hermetic glass rectifier. High reliability and high tolerance of thermal cycling and high temperatures.Originally Telefunken, I believe.EDIT: correction, it's called a "sintered glass" rectifier.

author: drussell
author_rank: Super Contributor
timestamp: September 16, 2018, 05:17:45 pm
content: That looks like an SOD-57 size package, SOD-64 is a bit "fatter" and "rounder." Not that the package type helps much since you used to even be able to get 1N400x series diodes in that package, it could be anything...Argh... Are either one of those still good so you could do some tests?It does seem to be an awful lot like a Telefunken part number, though:https://www.tedss.com/2028003173https://www.vishay.com/docs/86028/byt51a.pdfetc...Edit:Also, what are these diodes out of? What is the application?
Need help to identify SMD Microphones - Page 1
Forum section: electronics / projects

author: 0xPIT
author_rank: Regular Contributor
timestamp: March 15, 2018, 05:45:26 pm
content: Hi,so I've got those SMD Microphones from a dead Livescribe Digital Pen.I'm looking to identify the parts and if those are analog or I2S microphones.Markings:S121 6842S122 7140Maybe anyone knows something about the parts? I'm looking for a datasheet or at least pin-out.Thanks,pit
Need help to identify this chip - Page 1
Forum section: electronics / projects

author: gordonfromgotham
author_rank: Newbie
timestamp: May 11, 2016, 03:24:33 am
content: The code seems to be:AC1538D85107-03BThe first two letters might be different. The device is a bluetooth speaker.Thanks.

author: Wor3d
author_rank: Contributor
timestamp: May 22, 2016, 11:27:02 am
content: It looks like some custom-made IC, or just re-branded, custom chip number (if you buy enough of them, you can have there written whatever you want), etc.

author: amyk
author_rank: Super Contributor
timestamp: May 23, 2016, 05:42:57 am
content: That looks familiar...https://www.eevblog.com/forum/reviews/teardown-antec-shower-speaker/More with the same "JL" logo:http://www.weixinyidu.com/n_1774552http://www.taker.im/review/9569-FM-transmitter-Bluetooth-USB-i-microSD-pleer-nehttp://www.ymxd0802.com/yumingxingda/Product.asp?BigClassName=%BD%DC%C0%ED%B7%BD%B0%B8%B2%FA%C6%B7&Smallclassname=%D0%BE%C6%AChttps://fccid.io/pdf.php?id=2531058"The AC410x family is a low-power, high-performance microprocessor with 96KB SRAM"Following that lead, we get the Chinese name of the company, and...http://zh-jieli.com/Bingo. "ZhuHai JieLi Technology Co.,ltd". No AC1538 listed there though, but my best guess is that it's some sort of microcontroller. There is an email on that page, if you feel like giving that a try...
Need help to source 10 conductor cable that is 3.5mm thick, preferably shielded. - Page 1
Forum section: electronics / projects

author: XOIIO
author_rank: Super Contributor
timestamp: November 23, 2018, 05:54:23 am
content: Hello all, so turns out the cable I thought would work leaves me a couple wires short, I need some 10 conductor cable that is rougly 3.5mm thick, honestly as close to 3.5 as possible would be perfect because it's fitting in grommets, maybe 3.6 or so would work too, that is shielded if possible.I'm fine with either twisted enameled wires on the inside, or individually sleeved wires, maybe in the 30-28 awg range, doesn't matter a whole lot but if possible I'd like to use it to split a lithium ion battery supply between the two sides of this project.I haven't a clue where to start looking for this stuff, and I don't need much, so something where I could just buy by the foot would be ideal. I'm hoping someone here can find something suitable for me, or point me in the right direction.The jacket for the outside doesn't really matter much, plain old pvc or whatever is fine, but I'm hoping to find something without printing.

author: XOIIO
author_rank: Super Contributor
timestamp: November 23, 2018, 07:06:25 am
content: Quote from: blueskull on November 23, 2018, 06:03:39 amOh yeah, shit! I discounted usb from my mind as I don't have anything that uses type c ports, but if I can find one thick enough that will probably be basically perfect, and close by. I'll have to stop at a computer shop sometime tomorrow with some calipers.

author: LapTop006
author_rank: Unknown
timestamp: November 23, 2018, 11:03:57 am
content: Do make sure to find a cable that's built for USB-3 data though.A cable with only USB-2 data probably won't have enough conductors.
Need help to understand hydrophone specs - Page 1
Forum section: electronics / projects

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: July 08, 2015, 07:05:23 pm
content: I found a hydrophone unit that appears to be of very good performance, but then I looked at specs I see this:Receiving Sensitivity ( at 1 kHz ) ............................... 115 +/- 2 dB rel 1 pC / 1 uPaI am really unsure how to interpret it. I expected sensitivity to be a negative value in Db. as V/uPa but instead I see a positive Db value with 1pC/1uPa. What is pC ?How can I convert it to V/uPa?

author: fcb
author_rank: Super Contributor
timestamp: July 08, 2015, 08:43:43 pm
content: I agree, it looks like it needs more context. Can you link to the datasheet?

author: ConKbot
author_rank: Super Contributor
timestamp: July 08, 2015, 09:05:49 pm
content: PicoCoulomb, its a charge output transducer, but I agree that that is an odd value, cant really make sense of it in my head either.

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: July 08, 2015, 09:26:44 pm
content: link:http://www.ebay.com/itm/181769482491?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITNo datasheet anywhere.I found it, finally ... ufffff ... in some small old scanned paper from 1970s entitled "calibration of hydrophones".pC stands for "charge sensitivity" and it is written as 1pC/uPa.Sq = Sv * (Capacitance of hydrophone + Cable)where Sq is a charge sensitivity and Sv is voltage sensitivity (V/uPa).So in my case value 115 Db 1pC/uPa can be translated as V/uPa in dB10*log10( 10^(115/10) / (11500e-12+1500e-12)) which is equal to193.86 dB 1V/uPa. Huray!!! unless I made mistake somewhereCapacity was also given in small spec sheet that I have:Capacity at 20 °C .... ( at 1 kHz ) .............................. 11500 pF +/- 1500 pFI ignore the cable because spec is for hydrophone without the cable.193 dB is not bad but not exciting. I found few at 209-216 dB at similar prices.

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: July 09, 2015, 12:17:09 am
content: Quote from: ConKbot on July 08, 2015, 09:05:49 pmYes, you right pC it is picocoulomb - with relation to "charge sensitivity" it all make sense now!
Need help to understand schematic - Page 1
Forum section: electronics / projects

author: sudni
author_rank: Newbie
timestamp: February 28, 2023, 09:54:10 pm
content: In this shematic I don't understand the connection of each push buttons.do you have an idea?Thanks in advancePaul

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 28, 2023, 09:57:58 pm
content: This is a keyboard matrix. A simplified diagram of this:http://www.suppertime.co.uk/blogmywiki/2020/08/microbit-computing-fundamentals/slide1b-rows/

author: RoGeorge
author_rank: Super Contributor
timestamp: February 28, 2023, 10:06:07 pm
content: A push button has 2 pins. One pin goes to its column (the above resistor), and the other pin goes to its row (the left side resistor).The following schematic shows a keyboard matrix drawn more clear, not identical with yours, but similar:Image fromhttps://www.researchgate.net/figure/Matrix-keyboard-connection-to-ports_fig6_317699310However, the schematic you posted functions in a different way than this one. Yours will produce at the GP0 pin a different voltage for each button pressed.

author: planet12
author_rank: Regular Contributor
timestamp: February 28, 2023, 10:13:26 pm
content: Quote from: sudni on February 28, 2023, 09:54:10 pmIn this case, GP0 will be being used as an analogue input - ie. configured in the PIC as an A/D input.The resistors will be different for each row/column, thus forming a voltage divider with the bottom resistor that gives a different voltage for each individual button. This is a sneaky way to get a button matrix working using only one I/O pin.EDIT: For clarity, the buttons themselves will be connected as shown in RoGeorge's image.

author: Benta
author_rank: Super Contributor
timestamp: February 28, 2023, 10:46:51 pm
content: Yeah, it's a way to generate 16 voltage levels from a keyboard. Pin-saving, but with random results if more than one key is pressed at once.
Need help to understand the circuit pls. - Page 1
Forum section: electronics / projects

author: Chriss
author_rank: Frequent Contributor
timestamp: December 18, 2018, 09:24:57 pm
content: Hi!I trying to understand a part of this circuit:but have some problems to understand for what is the:D1 or D2 and C1 or C2 and why are the R2 and R6 connected to Ub=12V?Especially I'm interested in the C1 or C2 cap's, why they are in series with the B of the T1 or T2?And the R2 or R6 why that is needed?Thank you.My best regards.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 18, 2018, 09:31:14 pm
content: R2 and R6 don't seem to be very useful; the transistors will only turn on when the input pins are driven with more than about 5V peak to peak.Tim

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 18, 2018, 10:23:47 pm
content: This is probably some adapter made to be plugged to RS232 ports.Pins 4 and 7 are DTR and RTS signals, and are typically +/-5V to +/-12V signals.The diode is there to clamp negative voltages since as said above, the input signals can go as low as -12V.The capacitor is there to form a monostable multivibrator. The output pulse (open collector) will have a fixed duration as long as the input pulse (positive) is longer than the time constant.A common trick to ensure a fixed pulse duration here, since it's probably meant to be driven from a PC's RS232 port and the timings of the DTR/RTS signals can't be accurate.

author: Chriss
author_rank: Frequent Contributor
timestamp: December 19, 2018, 09:50:39 am
content: Yes, the circuit is an adapter driven from a PC RS232 port.Thank's for that nice explanation.My best regards.
Need help troubleshooting a TV Typewriter - Page 1
Forum section: electronics / projects

author: rea5245
author_rank: Frequent Contributor
timestamp: April 02, 2023, 05:40:08 pm
content: Hi,I have an old SWTPC CT-1024, which is a dumb terminal based on Don Lancaster's famous TV Typewriter. It works fine at 110 baud. There were instructions for adding more baud rates to it, and I'm trying to do that, but it's not working.The schematic is below, with the relevant section boxed in red. I've also attached the component values. I'm a hobbyist who can do some digital electronics, but this crystal circuit is outside my area of knowledge.Y-1 is a 307.2KHz crystal. I verified the crystal works, before soldering it in, by feeding it a sine wave from a signal generator at 307.2KHz, and viewing on a scope that it's resonating at that frequency, and not at others.IC8 is a 74LS04 hex inverter (the original design called for a 7404). IC9 is a 7474 dual flip flop.So if I understand this correctly, a 307.2KHz square wave should appear at IC9 pin 3. But I'm seeing a constant 5VIC8 pin 5 (the input to the first inverter) is seeing a slightly distorted sine wave, about 44MHz, ranging from about -3.5V to +6V.Since this wasn't working, I removed the crystal and re-tested it, to make sure I didn't break it the first time. It was OK, so I re-soldered it back in.How can I go about troubleshooting this?Thank you,Bob

author: intabits
author_rank: Frequent Contributor
timestamp: April 07, 2023, 12:18:49 pm
content: Quote from: rea5245 on April 02, 2023, 05:40:08 pmMy suspicion is that IC8 with it's associated resistors and capacitors are operating more in the analog realm. The LS version with its lower currents would need those other parts adjusted accordingly. The simplest solution would be to just use a standard 7404, as the other components are designed for its operating characteristics, not for an LS part.

author: rea5245
author_rank: Frequent Contributor
timestamp: April 07, 2023, 12:21:48 pm
content: Quote from: intabits on April 07, 2023, 12:18:49 pmThanks. I'll give it a try.

author: rea5245
author_rank: Frequent Contributor
timestamp: April 12, 2023, 10:19:43 pm
content: Quote from: intabits on April 07, 2023, 12:18:49 pmIt took me this long to get a 7404, but I got it, I tried it, and it works!Thank you!
Need Help Understanding How The "Power Supply" Part Of This Synth Works - Page 1
Forum section: electronics / projects

author: Efe_114
author_rank: Contributor
timestamp: May 26, 2022, 09:46:23 am
content: Basically the title. I have no clue how this power supply works and what "D/A Width" is supposed to mean in a power supply. Please help me out with understanding this.

author: jeremy
author_rank: Super Contributor
timestamp: May 26, 2022, 11:02:04 am
content: D/A width appears to refer to a knob with that name on the front panel, and the knob is depicted in the schematic as potentiometer VR1.

author: jeremy
author_rank: Super Contributor
timestamp: May 26, 2022, 12:03:31 pm
content: From my very quick look:- T1 forms a flyback converter to change +9V into a positive and negative voltage of some sort which is isolated- D4 is used as a basic voltage reference, and then opamp 1b does some filtering and gain on this to generate the main analog voltage rail- the main rail is then divided down using R5 and R6 into various voltage references, and then buffered through opamps 1A and 2A- opamp 2B converts the unknown negative voltage into a regulated -5V based on the main analog voltage rail and an inverting configurationSo basically a flyback makes an isolated +/- supply, then some reference voltages are made using resistor dividers, and then these reference voltages are buffered by some opamps.

author: Efe_114
author_rank: Contributor
timestamp: May 27, 2022, 10:25:51 am
content: Quote from: jeremy on May 26, 2022, 12:03:31 pmThanks for answering, I have 2 more questions if you could answer.How does that flyback circuit actually oscillate? I thought the same but I decided otherwise because I couldn't spot an oscillator.Why do they have the transistor outside of the 1b amplifier feedback loop?

author: jeremy
author_rank: Super Contributor
timestamp: May 27, 2022, 10:32:21 am
content: https://electronics.stackexchange.com/questions/377753/understanding-a-single-transistor-flyback-transformer-drivermight be of help here.As for the BJT outside of 1b, perhaps it is for power supply sequencing? Not really sure.
Need help understanding tlp127 - Page 1
Forum section: electronics / projects

author: psxpetey1
author_rank: Regular Contributor
timestamp: December 09, 2023, 10:20:07 pm
content: So my project is this triggering a 100v old style pc sync flash using a tlp127 in between it and the camera.I connected a power source to anode 1.2v 10ma and cathode to ground and the pc sync positive to collector and negative to emitter.I assume that once I connect the source the tlp would send the collector voltage to emitter to trigger the flash.But it doesn’t trigger.Data sheet:https://www.mouser.com/catalog/specsheets/Toshiba-TLP127.pdfCan someone help me outThis was the guide for the camera I was following :http://www.sx2pc.com/

author: MarkT
author_rank: Frequent Contributor
timestamp: December 10, 2023, 10:50:55 am
content: The TLP127 is very slow to switch, 50µs turn-on time, so maybe its not fast enough to trigger the pulse transformer in the flashgun?This is probably a consequence of it being a photo-darlington rather than plain photo-transistor output.

author: psxpetey1
author_rank: Regular Contributor
timestamp: December 10, 2023, 02:21:23 pm
content: Quote from: MarkT on December 10, 2023, 10:50:55 amwell this is a very very old flash over 1 minute to charge from 1974 Honeywell strobnar 100. My next idea is to try a led on the emitter to see if the tlp works maybe it’s broken I have extras but ya maybe they do have a flash list on the old page. I have used a constant power source as well so it should turn on and eventually fire the flash you would think.

author: psxpetey1
author_rank: Regular Contributor
timestamp: December 11, 2023, 07:02:16 pm
content: That may be the problem I guess I’ll have to open the flash and see what it’s got going on in there I tested it with a led and the tlp was working. With a power source. Funny that the tlp with a constant power source for the led on the collector emitter won’t trigger that led either so maybe like you said the turn on time is too slow maybe 🤔. In his old project he used triacs for high voltage and the tlp for low voltage flashes I guess I’ll have to do some more research and maybe buy a flashbar just to double check my sx70 flash ability as well. Any suggestions for faster photocouplers
Arduino mega 2650 for a small CNC - Page 1
Forum section: electronics / projects

author: sourcecharge
author_rank: Regular Contributor
timestamp: March 23, 2019, 10:11:04 pm
content: Arduino mega 2650 chipsetIt's a D6 MB with Marlin 1.1.9 firmware that I have been able to modify and understand.It can connect directly to a computer via a USB cable and I have found that "pronterface" can directly connect to it and move the steppermotors.My next step is to get mach 3 and fusion 360.The railing system should be the easiest part but still needs to be made.
need help wiring a circuit - Page 1
Forum section: electronics / projects

author: squid
author_rank: Newbie
timestamp: December 10, 2013, 05:58:26 pm
content: hii need help wiring a circuit to ensure i dont mess things up or break the project im doing,im a complete novice and this is a one off project,i have made a basic drawing or the parts on paint drawing i just need someone to fill in the wires like positive and negative where they go on the drawing , i will upload all the parts and spec of them so you know whats involve and if anything is need like extra protection etclink to touch sensor ichttp://www.hobbytronics.co.uk/touch-switch-iclink to tactile switcheshttp://uk.rs-online.com/web/p/tactile-switches/0102383/5v charge boardhttp://www.ebay.com/itm/140991545937?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649the dc buck converter details are on the upload i have uploadedwould be very grateful if some one could help and fill in the wires on the paint drawingmany thanks

author: Kevin.D
author_rank: Frequent Contributor
timestamp: December 10, 2013, 07:16:32 pm
content: Hello Squid . So you want to make your own electronic cig mod. Personally I dont think I would use a touch switch on one of those ,who suggested you use one of them ? .They can be pretty unreliable sometimes ,when you get grease/dirt on them they can sometimes start to fire on there own ,and you dont want that to be hapening with your E.cig . I would stick to using tactile switches only to be on the safe side .go herehttp://www.e-cigarette-forum.com/forum/and look into the "modding forum" section and ask there ,you will get lots of advice from other to help you .

author: squid
author_rank: Newbie
timestamp: December 10, 2013, 07:29:42 pm
content: Quote from: Kevin.D on December 10, 2013, 07:16:32 pmit was my idea to use the touch pad thought was a good idea clearly not lol,just thought it might had been due touch application been used in mist all thing now days,no doubt vastly more tech spec than what i was making lol
Need Help with a Basic Design Question - Page 1
Forum section: electronics / projects

author: Cigarsnob
author_rank: Regular Contributor
timestamp: October 19, 2013, 08:24:48 pm
content: Hey everyone,I feel like an idiot for having to ask this, but I need some help with a calculation question regarding an opamp gain based off an NTC thermistor (10kohm). In short, an APD is being temperature monitored to adjust the bias voltage. As the temperature increases, I want the bias voltage to decrease. I'm using an NTC thermistor to monitor the temperature and adjust the gain of an amplifier, which adjusts the high voltage regulator. See link below for the opamp configuration and a chart for the APD being used.http://imgur.com/a/h5G6JI want the APD to have a gain of 50. The chart given plots gain vs bias voltage for three different temperatures (0C, 25C, 50C). The opamp with the thermistor is configured in a non-inverting amplifier. The second page of the link has a little table of TC, VHV (High voltage), Divide by (this is how much the high voltage is divided by for the feedback), and the gain of the amplifier under question.My question is, how do I calculate the gain of the amplifier? When I first tested the circuit, I left out the thermistor and just did a simple non-inverting amplifier to give me a gain of 1.33, which gave me a high voltage of 115V. Based off the APD chart, I know from 0C to 50C that there's a change of 80V over a 50C change. Which gives me a 1.6V change per degree C. Does this play into the equation of determining the gain?I was thinking about taking the three temperatures for a gain of 50 for the APD. With that gain of the APD and the bias voltage required, I know the gain of the opamp (given in the table shown on page two as previously mentioned). From this, I have three unknown resistors and three gains. If I calculated the gain equation correctly (see page 1 for the equation, 1+k, where k is some resistor combination shown), then I know it needs three different gains. Solve the equations for each of the unknown resistors (3 total). But I feel this is incorrect as I'm using the same equation, but each equation just equals a different gain.My apologies in advanced if this is confusing. I'm just trying to type out everything that I'm thinking. Any help is welcomed.Thank you

author: tszaboo
author_rank: Super Contributor
timestamp: October 19, 2013, 10:01:23 pm
content: I think that the problem is that you want to solve a non-linear problem, with linear tools. If I were you, I would enter the NTC characteristics, and the APD (is that the photodiode BTW) characteristics in Excel (or equivalent) and go from there. Calculate the gain for every 5 Kelvin, and see if you can solve it with a setup.But as far as I see, it might not be trivial. It might be more time economical to solve the problem with a microcontroller look-up-table.

author: Cigarsnob
author_rank: Regular Contributor
timestamp: October 20, 2013, 12:47:44 am
content: Quote from: NANDBlog on October 19, 2013, 10:01:23 pmThanks for the feedback. The APD is an avalanche photodiode. I'll go the route of Excel (probably matlab though) and take it from there.
Need help with a PFC controller - Page 1
Forum section: electronics / projects

author: Jolle
author_rank: Contributor
timestamp: May 09, 2012, 10:17:05 am
content: HiI am designing a 120W PFC using a Texas instument UCC28051 controller. The converter works as it should when I look at the output voltage, which is about 396 V, but when I look at the current through the inductor it looks like the controller enters some kind of burst mode?!You can see a plot of the inductor current (green) and gate signal (yellow) below, during a 50 Hz cycle, the converter was delivering 60 watt to a load when the plot was made:Has anyone seen a PFC behave this way before and know why it behaves as it does?Regards

author: muvideo
author_rank: Frequent Contributor
timestamp: May 09, 2012, 10:57:51 am
content: I would check these:- core saturation (linear voltage ramp on CS pin)- spikes on CS pin- device supply voltage Vcc- ZCD pinDoes the output voltage fall or is regulated?Fabio.

author: Kremmen
author_rank: Super Contributor
timestamp: May 09, 2012, 11:13:54 am
content: But isn't it supposed to behave something like that? A PFC is doing 2 things: maximize cos(phi) i.e. make voltage and current equal in phase, and secondly minimize current spiking due to capacitive load. The ideal would be a resistance-like V/I curve. The PFC cannot do anything to the instantaneous line voltage but by modulating it can distribute the current more evenly over the half-wave.Just by looking at the picture i cannot say if that is what it is doing, or if it is some fault condition.

author: muvideo
author_rank: Frequent Contributor
timestamp: May 09, 2012, 11:34:05 am
content: Quote from: Kremmen on May 09, 2012, 11:13:54 amAs far as I know to do so that current envelope should be like a sinusoid semiperiod,the control loop then changes (acts on time scales slower than a semiperiod)the current value to regulate the output voltage on the capacitor bank.Fabio.

author: Kremmen
author_rank: Super Contributor
timestamp: May 09, 2012, 11:39:34 am
content: Well yes, but i am not familiar with that chip and its capabilities. In case it just does a rough approximation this could be the result. Or then it is just malfunctioning.

author: Jolle
author_rank: Contributor
timestamp: May 09, 2012, 01:36:31 pm
content: Kremmen hit the nail on the head with the comment about my IC being malfunctioning. I hadn't thought of that since the controller was regulating, but when I soldered on a new IC everything worked fine and my PF is now very close to 1So thanks to all of you who helped me with my relative simple problem.
Need help with a project - Page 1
Forum section: electronics / projects

author: challie2
author_rank: Contributor
timestamp: November 06, 2019, 09:06:40 pm
content: Hi all I really need some help!I have 3D printed a case for a PCB Device that uses a small SMD tactile button switch as the power on/off.The issue I have isThe original switch pusher (As I do not know the actual name of it) is long gone. I need the new plastic piece that is usually a component of the case, that presses down on the push button switch, similar to the xbox or playstation controller buttons but slightly larger, currently I am using a rubber nib on a pencil to operate the device through the 10mm hole. Any ideas what these plastic button switch pushers are actually called and also where to find them?ThanksJamie

author: Apollyon25_
author_rank: Regular Contributor
timestamp: November 06, 2019, 10:55:36 pm
content: Measure up what you need, design it, print it???

author: challie2
author_rank: Contributor
timestamp: November 07, 2019, 08:33:10 am
content: I tried that, but I fancied a metal button with a solid feel. You can get metal filament but they are a bit naff and Im using the best filament money can buy at £300 per spool!What I can do is re-design the hole to fit an off the shelf (switch pusher). But I need to know where I can find them.

author: beanflying
author_rank: Super Contributor
timestamp: November 07, 2019, 08:59:15 am
content: Try "tactile switch cap" for a search on evilbay or this one on Aliexpress this is actually a section for themhttps://www.aliexpress.com/category/200215992/switch-caps.html?spm=a2g0o.productlist.0.0.785c242cRDe291Chromed plastic is available but I only have 6mm diameter (flange is 9.25mm) ones so I am not sure if there is a 10mm diameter.Edit: Quick search found these 10mmoneseBay auction: #264289143215

author: Gyro
author_rank: Super Contributor
timestamp: November 07, 2019, 10:02:36 am
content: If you get the dimensioning and holes size right, stainless steel ball bearings can be very effective. I've seen them used on HiFi products.
Need help with a switched-mode CCCV module - Page 1
Forum section: electronics / projects

author: Plecto
author_rank: Regular Contributor
timestamp: October 25, 2018, 07:36:11 am
content: Hello. I'm working on a variable constant-current-constant-voltage regulator. Two PWMs are supposed to set the maximum allowable current and maximum allowable voltage and the regulator will output whatever voltage needed to meet those criterias. The schematic below is my first attempt (please disregard the two fets in the bottom right as well as C88). The output voltage of the switching regulator is manipulated by adjusting the voltage in it's feedback path, either directly from 'Output_Voltage_PWM' or through U1D which will raise it's output voltage if the output current goes above the set current threshold. This circuit works as intended as long as the input voltage is kept below ~20V, but at 48V input the regulator get's unstable in all sorts of fashions at different output voltages and more often than not it will cause my power supply to go into current limit by allowing shoot-through (the fets gets really hot). I've read the datasheet of the LM5117 and tried following the examples, but my knowledge when it comes to transfer functions and feedback compensation is limited so I'm kind of in the dark when selecting component values. I can't really follow the formulas in the datasheet completely either as I want a variable output voltage (the formulas often require a specified output voltage). Could someone help me out selecting component values that would lead to a stable regulator regardless of set output voltage? Or perhaps a different approach entirely would be better?

author: prasimix
author_rank: Unknown
timestamp: October 25, 2018, 08:42:52 am
content: Take into account that even with properly selected compensation network if you didn't succeed to layout PCB correctly you can expect all types of issues as you mentioned (usually that starts to be visible with increase of input or output voltage or power).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 25, 2018, 02:54:43 pm
content: Noooo! Why do it voltage-mode only, when you have access to the internal current control node?http://www.ti.com/lit/ds/symlink/lm5117.pdfpage 12V(COMP) - 1.2V is compared to the measured/estimated output current. The pin can sink/source at least 3mA, implying the error amp is a conventional voltage-mode op-amp, and probably shouldn't be overdriven*. So, we should use a feedback clamping circuit instead, like this:The error amp and feedback network is the internal error amp, so the discrete circuit only needs to attach to the FB and COMP pins, with everything else as normal in the application circuit.*This is handy in transconductance type error amps, where the COMP node is loaded with an R+C to ground to set compensation (rather than an R+C feedback to -in, as a voltage-mode amp uses), and V(COMP) min/max can be set with simple diode clamps. TPS54233 for example can be used this way.Tim
Need help with AC detector/battery switch - Page 1
Forum section: electronics / projects

author: Randroid
author_rank: Newbie
timestamp: May 20, 2014, 01:52:16 am
content: Hey all,I've attached a (very) basic block diagram of my circuit. I'm working on a project that is powered by AC, but has a battery backup when the AC power drops out which will happen from time to time. My boost chip doesn't have an enable pin, so I need a way to keep it disconnected from the battery when the AC power is present. I want to try to use a pFET as a switch at point A, but I'm not sure what the best approach is going to be.There is a microprocessor involved, and it's been suggested that I use an optocoupler as an AC detector to trigger an interrupt and switch a FET but I'm not familiar with that type of circuit. If anyone has some ideas or suggestions about the most robust way to accomplish this, I'd appreciate any input!Please let me know if my post needs any clarification.

author: DJ
author_rank: Unknown
timestamp: May 20, 2014, 01:59:24 am
content: Diode-or the power supplies together. Tap off the ac, rectify it, divide it down and feed a comparator driving the enable pin of your boost converter.Helps if you detail voltages, load currents, etc

author: Randroid
author_rank: Newbie
timestamp: May 20, 2014, 02:12:41 am
content: My boost converter does not have an enable pin unfortunately. I haven't been able to find a boost converter with an enable pin that fits my specs - 3.7V input from battery, 9V-12V output, around 12-15 W out of the boost max. I've found plenty of boost controllers, but I'm trying to use a self contained IC for this project instead of designing my own booster.The AC/DC converter is universal so it takes 85-240V, 50-60Hz and outputs 12V, 25W (though I shouldn't ever be above 12-15W).

author: expert_vision
author_rank: Newbie
timestamp: May 20, 2014, 02:51:18 pm
content: I have designed this for on of my projects and it works pretty well, the uC doesn't sense when power is being swapped; uC doesn't reset.Adapt to your needs. Hope it helps.Couldn't attach the picture so I posted on imgur ...

author: expert_vision
author_rank: Newbie
timestamp: May 20, 2014, 02:55:59 pm
content: I have designed this for on of my projects and it works pretty well, the uC doesn't sense when power is being swapped; uC doesn't reset.Adapt to your needs. Hope it helps.Couldn't attach the picture so I posted on imgur ...
Need help with ADC analog input design - Page 1
Forum section: electronics / projects

author: mem2mem
author_rank: Newbie
timestamp: April 09, 2021, 04:47:23 am
content: Hi,I'm using AD7190 to sample single-ended voltage and having trouble on design its RC input filter. According to the datasheet, I should put a 100 Ω resistor in series with each analog input, a 0.1 μF capacitor between the analog inputs and 0.01 μF capacitors from each analog input pin to AGND. If I want to sample single-ended voltage instead of differential voltage, does this 0.1uF capacitor between analog inputs needs to be removed? I understand that this 0.1uF capacitor also served as a charge capacitor to charge the input capacitor of the ADC. If this 0.1uF capacitor is removed, should I increase the capacitor from each analog input pin to AGND? How can I calculate the value of these capacitor?Thanks!
Need help with AM transmitter. - Page 1
Forum section: electronics / projects

author: Anson
author_rank: Regular Contributor
timestamp: September 24, 2013, 01:52:05 am
content: I want to build an AM transmitter that I can tune an old 30's am tube radio into. I would like to have it be able to transmit from inside the radio. I need it to have the ability to play mp3's off an SD card and also receive a fixed FM frequency 93.7 and then transmit on AM. Possibly two separate channels. so you can just tune on the radio and not have to mess with the transmitter. This is a project for my mom. I recently started trying to restore old radios and have one I am working on for her but she wants to be able to listen to her station and it would be nice for her to be able to just play her music on it. I would appreciate any help.

author: zapta
author_rank: Super Contributor
timestamp: September 24, 2013, 03:46:28 am
content: Some of the older radios had external audio input for record players. If it does, you can feed audio directly, without a transmitter.As for AM transmitter, there are kits, like this onehttp://www.amazon.com/Ramsey-AM1C-Radio-Transmitter-Kit/dp/B0002NRJCM

author: dannyf
author_rank: Super Contributor
timestamp: September 24, 2013, 04:10:36 am
content: A crystal oscillator in the AM band, a resistor + a cap + a short wire = an AM transmitter.
Need help with an alternate part!   - Page 1
Forum section: electronics / projects

author: samsmock
author_rank: Newbie
timestamp: December 03, 2018, 06:45:50 pm
content: I've got PCB's that I've built for years. Parts went obsolete on them years ago.I bought a bunch from Hong Kong and have had enough to keep me going for quite a while. Now I'm looking again. One of the suppliers pointed me to a possible substitute for the flip flop I've been using. I've never come across it before, and would like to get someone elses opinion of whether or not it's a match.Things look like they'd work to me, but I want to make sure I'm not missing something.So the part I've been using is here.http://pdf1.alldatasheet.com/datasheet-pdf/view/53719/FAIRCHILD/MM74C74.htmlThe alternate they are suggesting is here.http://www.alldatasheet.com/datasheet-pdf/pdf/15662/PHILIPS/74HC74D.htmlCan someone double check me on this?

author: tsman
author_rank: Frequent Contributor
timestamp: December 03, 2018, 07:25:32 pm
content: There are several differences between those two parts. Things like the timings + propagation delays are completely different. The supply voltage range is far bigger on your old MM74C74. Only you can tell if it is compatible by looking at the rest of your circuit.

author: Benta
author_rank: Super Contributor
timestamp: December 03, 2018, 07:37:26 pm
content: If your circuit is running a 5 V supply, the 74HC74 is a drop-in replacement, although the faster signal edges/delays may cause issues.If your circuit is operating at higher voltages, eg, 12 V, the functional replacement is the MC14013/CD4013, which will require a PCB layout change or an adapter board.

author: samsmock
author_rank: Newbie
timestamp: December 03, 2018, 08:18:55 pm
content: Yeah, it's running at 5v. I may order some samples. Unfortunately, I do the assembly part and am out of touch with the guy who designed it for me in 2007!

author: t1d
author_rank: Super Contributor
timestamp: December 05, 2018, 06:26:21 am
content: Don't forget about checking directly with the OEM for what they suggest as a sub. They have technical assistance, just for this purpose. And, the big component distributors also have personnel to help you with this very type of issue. Mouser, Digikey, etc.In doing your research, if you discover a new method to track down parts, please post it here.

author: aju11
author_rank: Contributor
timestamp: December 06, 2018, 10:37:10 am
content: 1. Check the supply on the board.2. Check the noise margins. Voltage levels of clock, data and reset lines3. Check compare timing diagrams
Need help with Arduino PWM Motor Control - Page 1
Forum section: electronics / projects

author: timdriedger
author_rank: Contributor
timestamp: July 31, 2013, 05:33:54 am
content: Hi Everyone,This is my first visit here. Hopefully this is the right crowd for some help.I'm using the following circuit to control a DC motor with an ATMega (Arduino).There are many articles out there that refer to a simple circuit like this but I know from doing some reading that they don't really follow best engineering practice. It's kind of just enough info to be dangerous!What should I change in this circuit to provide good component life and more importantly, noise suppression.MOSFET Datasheet:http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Components/General/FQP30N06L.pdfThe motor is a truck window lift motor running on 12V, draws about 2-4 amps in our application, 6-9 amps if it heavily loaded. The wires running to the motor are about 10ft long.The PWM rate is 32kHz.Thanks,Tim

author: Odysseus
author_rank: Regular Contributor
timestamp: July 31, 2013, 08:38:08 am
content: Directly PWM'ing a motor is not ideal. It's fine for LED's, but DC motors are another story. I tried it a while back in my very first micro-controllers class. It worked, but wasted more power than it saved.That said, the circuit as shown will function, but the turning it into a proper switch-mode speed controller withmuchlower noise only requires the addition of a couple of caps and an inductor. It doesn't really change it's fundamental behavior, it's just a filter (in a much simplified view).Capacitor and inductor values in the attached schematic should work well. Just make sure everything has sufficient ratings, particularly ripple current for the caps. At least 1 amp RMS for the 100uF and 100mA for the 10uF. I'd double that to be safe. Also the inductor needs a DC current rating for the full load current. It's gonna be beefy. Also, you can use any mosfet or diode that can handle the currents.When actually constructing this thing, keep the current loops short to avoid radiating noise. There's one loop through C1, C2, L2, and M1 during the on time of the fet. Then it changes to D1, L2, and C2 when the fet turns off. So your motor and voltage supply can be located relatively far away, but keep all of these components physically close together.
Need help with bridge rectifier - Page 1
Forum section: electronics / projects

author: Crambone
author_rank: Frequent Contributor
timestamp: October 04, 2019, 01:34:04 pm
content: I need a Bridge rectifier to replace S10VB10 83 I’m not sure what can be used. It needs to be a through hole mounted type like in the pic.Thank you

author: MarkF
author_rank: Super Contributor
timestamp: October 04, 2019, 02:14:56 pm
content: There are many. Here is just one:https://www.mouser.com/ProductDetail/Rectron/MP258W?qs=sGAEpiMZZMtQ8nqTKtFS%2FNgL6ac11fJuaLnYiNhSIQo%3D

author: Crambone
author_rank: Frequent Contributor
timestamp: October 06, 2019, 01:00:32 am
content: Thanks!
Need help with buying Voltage Transformer - Page 1
Forum section: electronics / projects

author: ajoseph88
author_rank: Contributor
timestamp: October 27, 2015, 02:01:59 pm
content: I am searching for a voltage transformer, 230V AC 60Hz on the primary and 4 different voltages on the secondary as in the circuit attached...VA rating anything between 75VA to 250VA, and its for PCB mount, or if not... i will mount it on heat sink....I found an exact similar transformer in an old reliance drive (pics attached), but that part is no more in production... And i have spend a lot of time searching on the internet, but couldn't find it... Any one knows a similar model... any link to website. with similar model transformers....

author: Paul Price
author_rank: Super Contributor
timestamp: October 27, 2015, 07:11:49 pm
content: You are mistaken about the VA capacity of the transformer shown by a factor of ~100x. The transformer shown would need to be ~10x larger to handle that kind of power.You would need to contract a custom transformer company to source a transformer with this large number of secondaries and VA rating.Mounting a transformer on a heatsink doesn't keep it from overheating.If you have room for heatsinks then you probably have room for finding a place to mount 2 to 3 off-the-shelf discrete transformers to meet your requirements.

author: mariush
author_rank: Super Contributor
timestamp: October 28, 2015, 12:09:13 am
content: How much current do you need on each winding?It would probably be easy to buy a toroidal transformer with 4 x 18v separate windings, and connect two of them in series to get 36v. But, it depends on how much current you want on each of those windings... a ready made transformer would probably have each winding capable of same VA amount.Alternatively if you need high current only on that 36v, get a toroidal transformer for the 36v high current and manually add a few loops of wires to get the 12v you want for AC sync, and buy a separate low current transformer for the two 18v windings. Both should be available retail, in stores.ps. The transformer in your second picture is at best for 10-15 VA.

author: steve207a
author_rank: Contributor
timestamp: November 01, 2015, 07:07:48 pm
content: I would say from its size the transformer in the second pic is capable of about 1 amp max
Need help with capacitive touch switch/static buildup  - Page 1
Forum section: electronics / projects

author: valley001
author_rank: Frequent Contributor
timestamp: September 04, 2021, 08:00:16 pm
content: Hello all,I have a CRT clock here with a metal case (metal case is my design CRT clock kit is not) . I rigged it so I can toggle the display on and off via a capacitive touch module, the switch sends a 5v high signal to turn the display on and off in place of a momentary switch. The PCB and HV is isolated from the case obviously. The capacitive touch sensor is connected to the case via a small gauge wire. line power is delivered to the PCB and is ungrounded, so the case is basically floating. (CRT uses electrostatic deflection)This all operates fine however if I leave the display on for some time and then turn it off by touching the case/activating the capacitive touch sensor I get a static shock. This does not seem to cause any trouble to the microprocessor or other silicon devices, but I do see the display flicker and it is generally unpleasant. Can I solve this by grounding the case with a grounded line cord? Will this impact the capacitive touch scheme?Thanks all for your assistance.EDIT: Never mind, I think I have this sorted. I think it is ME developing the static and discharging into the metal case, rather than the clock developing the charge.

author: t1d
author_rank: Super Contributor
timestamp: September 06, 2021, 04:25:42 am
content: Just for you to develop ideas... The ESD wrist bands are just a metal contact pad, for you skin, a 1 Mega-Ohm resistor (of sufficient wattage) and a ground wire going to earth.