hybridfree/eevblog-posts huggingface dataset:
Potting - Page 1
Forum section: electronics / projects

author: Anson
author_rank: Regular Contributor
timestamp: April 07, 2013, 04:32:13 pm
content: Need a suggestion for a potting compound. My wife wants me to make an underwater LED light cube with various colors and alternate flashing patterns. there are a few things on the market but none that she likes. Before I work on the design of this I want to look into protecting my circuit first. Being this will be LEDS it won't be overly complicated. Would it be simpler and less expensive just to make a sealed acrylic enclosure, or to pot the thing? Can you use any kind of hardware store silicone to seal a board?

author: BravoV
author_rank: Super Contributor
timestamp: April 07, 2013, 04:36:26 pm
content: One of member here Rufus posted his experience with hot glue, read it your self ->Here, especially at the last paragraph.

author: Anson
author_rank: Regular Contributor
timestamp: April 07, 2013, 05:42:59 pm
content: Thanks! This should be a small enough project that this will work perfectly.

author: G7PSK
author_rank: Super Contributor
timestamp: April 07, 2013, 08:32:04 pm
content: I have used fiber glass (polyester) resin very successfully for encasing electronics and electrical connections. You can get special jointing connectors for underground armoured cables that use the same resin in a sachet that you just squish around to mix before cutting open and pouring into the joint. The resin also has the advantage of being fairly clear when set and you can get a variety that is almost glass clear when set, so would be very good for led's.

author: robrenz
author_rank: Super Contributor
timestamp: April 07, 2013, 11:23:21 pm
content: I know this is more than you need but this guys stuff is excellent. I have used the MCR black potting compund. If nothing else look thru his site for all the informative how to information.polymer products

author: skipjackrc4
author_rank: Regular Contributor
timestamp: April 07, 2013, 11:42:12 pm
content: Is clear epoxy out?

author: ConnorGames
author_rank: Regular Contributor
timestamp: April 09, 2013, 12:34:06 pm
content: Take a look athttp://runawaybrainz.blogspot.com/2012/04/audio-crystal-cmoy-freeform-headphone.html! Hopefully usefull, and certainly interesting!

author: travellerw
author_rank: Contributor
timestamp: April 09, 2013, 05:21:22 pm
content: I've used the following stuff very successfully.. You can even buy dying kits for it and have it any color, or black it out completely. Without dying it is super clear.Just follow the directions closely and know that it will take about 2 days to fully cure.http://www.amazon.com/Environmental-Technology-16-Ounce-Catalyst-Polyester/dp/B00172RK62/ref=sr_1_7?ie=UTF8&qid=1365527898&sr=8-7&keywords=resin+clear

author: Anson
author_rank: Regular Contributor
timestamp: April 09, 2013, 06:05:47 pm
content: Hmm that could work out really well. I could do custom colors.
POV Dsipay  - Page 1
Forum section: electronics / projects

author: pknoe3lh
author_rank: Regular Contributor
timestamp: June 05, 2018, 09:03:11 am
content: My new Projekt I want to show you:Result:https://youtu.be/CScyjsmp5GIEnglish version:https://youtu.be/yG3uugdAIMQGerman version:https://youtu.be/0-CgAIzA3GMTimelaps of the development:https://youtu.be/tsHWgNwWQd0It's a 132*131 pixel POV display (Persistence of vision)The idea is to have a nice project to show what FPGAs are needed for. You cannot do that in software without a really fast processor.

author: pknoe3lh
author_rank: Regular Contributor
timestamp: June 11, 2018, 09:04:26 am
content: I'm on Hackaday:https://hackaday.com/2018/06/11/fpga-persistently-rick-rolls-you/
Power a current loop from two sources (Sensor Tap) - Page 1
Forum section: electronics / projects

author: Sudo_apt-get_install_yum
author_rank: Regular Contributor
timestamp: April 11, 2018, 04:39:23 pm
content: Hi everyone!So I’m working on a project and I think I’m done with one part of it, measuring a 4-20mA signal and powering the circuit while there is potentially another power source. If another power supply is detected then it would use it and disconnect the internal power supply and if no other power supply is detected it will use the internal power supply. It would be some sort of 4-20 mA signal tap!Normally I check with my friends but they are off on vacation so I’m turning to you guys!I’ve tried this circuit design in LTSpice and designed it in Eagle (schematic and PCB) and it seems to work in the spice simulator but I’m not too sure if it’s something to work in practice (my gut says no).Would appreciate if somebody could just give some feedback on the Ida/design! (I’m just a student so don’t bash my Eagle skills)Thanks in advanced!Files posted:Theory of operation (Hand drawn picture of how I wish it would operate)LTSpice simulator (Screenshot of a simplified schematic with output)Eagle schematic (PDF of non-simplified schematic)
Power Amp for Bluetooth Transmitter - Page 1
Forum section: electronics / projects

author: Vasiliy
author_rank: Newbie
timestamp: June 19, 2012, 10:48:04 am
content: Hi all.I'm working on a student project. The aim is to design and test a Class E power amp to be used in Bluetooth transmitters.I have a few questions on the topic:1) BT transmitter should be able to hop between 80 channels spaced 1MHz apart. There is allowed level of interference between neighboring channels. How this requirement satisfied? Is there a variable filter at the output of the power amp?2) What is the common topology for output impedance matching network? I've seen a series capacitor and an inductor in parallel. Is assuming 50 Ohm for the antenna is Ok?3) Output power control: class 1 BT transmitters must provide a mean of controlling its output power. What is the common approach for implementing this control? Changing Vdd?Thanks to everyone in advance.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 20, 2012, 01:54:53 am
content: There are lots of chips that do exactly what you want. Just beware that the packages they come in are difficult to solder unless you have solder paste and a heat gun.http://www.maxim-ic.com/datasheet/index.mvp/id/2458

author: Vasiliy
author_rank: Newbie
timestamp: June 22, 2012, 09:33:13 am
content: Thanks NiHaoMike, but it's not what I need.There is no intent for this design to be implemented, it is just an educational project. The reference you've provided is a linear PA, which assumes that the input signal is properly filtered and shaped RF signal. The PA I want to design is switched mode (not linear). Its input signal is properly modulated (GFSK) square wave, which is assumed to be an output of Bluetooth transmitter's modulation circuitry. Once fed into non-linear amplifier this signal gets distorted, therefore filtering is required.When designing non-linear PA for a single center freq the filter may be as simple as a single LC tank, but in case of Bluetooth transmitter there are 80 different channels which should be supported, therefore there should be a mean of controlling the center frequency of the output signal.It seems to me that a possible approach would be to implement a digitally controlled filter at the output of the PA, instead of a constant filter. The questions are:1) Is variable filter really a way this issue resolved in the real designs?2) What is the topology of this kind of variable filter?Additional question:3) What is the common topology of impedance matching network for this kind of designs?Thank you.
Power architecture. Detriment to sharing 3v3 between MCU and FPGA? - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: February 01, 2018, 03:43:32 am
content: On a new design I'm taking a step back and looking at the overall power architecture and sequencing. The hope is to maximize reliability and robustness. This design will have both an MCU and a FPGA. The MCU will handle external COMs and program the FPGA on boot.From all of the FPGA design docs I've found it's seems to typically be 1.2V > 2.5V > 3.3VCould there be any reliability improvements if the 3.3V rail for the FPGA was separate and the power sequencer power-up both the FPGA and MCU 3v3 net?Typically my designs are made in the hundreds, I'm trying to think about the hundreds of thousands...

author: jbb
author_rank: Super Contributor
timestamp: February 01, 2018, 07:53:12 am
content: It could be useful to separate the MCU and FPGA power if you’re interested in a low power mode with MCU only.Otherwise I can’t help but wonder if more supplies means more problems. (Consider what happens if they come up out of sequence...)But I haven’t done a serious FPGA design, so more experienced people might have more insight.To play devil’s advocate: can you squeeze the MCU features into the FPGA with a soft core processor? Get the most out of an expensive part?

author: dmills
author_rank: Super Contributor
timestamp: February 01, 2018, 11:53:31 am
content: Be careful here, the FPGA will not much like having 3.3V from the micro on its IO pins while it is itself not powered (Same goes for the micro if the FPGA comes up first).Personally I usually sequence Core/Aux then a common 3.3V once those have come up.Do pay attention to things like the (sometimes seen) maximum voltage difference allowable between the FPGA Aux and IO bank rails (Xilinx looking at you), and especially the fact that this limit also applies during power shutdown!One other thing to watch is the overshoot limits on the FPGA pins, especially with 3V3 on FPGA pins you can cause damage by overshoot at the pin, 100R resistors are your friends (Altera make a big deal of this with 3.3V IO).These days I usually try to avoid 3.3V on FPGA based designs, 1.8 is sufficient and makes for a nice power saving (Plus, often you can use the same supply for the Aux rail).Regards, Dan.
Power Bank Improvement - Page 1
Forum section: electronics / projects

author: spencer_manzon
author_rank: Newbie
timestamp: January 01, 2015, 01:15:16 am
content: Hello everybody,I have a project that aims to improve one of my power banks.Here is the progress of my project:Since the original PCB (the blue one) of the power bank only puts out 4.3V (which is out of spec for usb charging), I salvaged a PCB (the green one) from a USB charger powered by 2x AA batteries which puts out a nice 4.9-5.1 volt output.Now, this is where things get complicated.1.) I wanted to connect the new charger PCB (the green one) to the old charger PCB (the blue one) via USB (there were two ports, I removed one port). Since the bloody blue PCB could not supply the current needed by the green PCB (which is 500-600mA, tested with a USB Doctor (blue box)) because the blue PCB could only output about 250mA on its "2.1A port", I set off for Plan #2.2.) Now, I noticed that I could turn on and off the LED flashlight on the blue PCB. I could wire up the green PCB on that one (added bonus of an ON/OFF switch) but I am uncertain of the current that the LED driver could put out. So, I set off for Plan #3.3.) Plan #3 is where I am troubled. I am choosing to keep the bloody blue PCB for its charging capabilities for the battery pack but I am torn in wiring the green PCB. I was almost gonna wire it directly to the battery pack (the battery pack is in parallel and are li-ion cells) but I was worried for the cut-off voltage for the pack. I am assuming the cut-off circuitry is in the blue PCB because it shuts off when the battery is used up. Will it be safe to wire it up or do I need to buy one of these:http://www.ebay.ca/itm/1pcs-1S-Li-i...639?pt=LH_DefaultDomain_0&hash=item3f42b5a2f7? By the way, the IC in the green board is a TD8228 which draws voltage as low as 2V.Thanks for reading my long post. Cheers!
Power calculation 4chanel HSD driver - Page 1
Forum section: electronics / projects

author: halexa
author_rank: Regular Contributor
timestamp: June 28, 2016, 06:21:51 am
content: Hi,How do you calculate total power of a 4 channel HSD driver?Example: Each channel loads 1A and each channel have 140m? RDSonCh1: 1A*1A*0.14? = 0.14WCh2: 1A*1A*0.14? = 0.14WCh3: 1A*1A*0.14? = 0.14WCh4: 1A*1A*0.14? = 0.14Wtot: 4*0.14W = 0.56WORtot: 4A*4A*0.14? = 2.24W

author: tszaboo
author_rank: Super Contributor
timestamp: June 28, 2016, 08:29:58 am
content: QuoteSorry, does not compute.

author: halexa
author_rank: Regular Contributor
timestamp: June 28, 2016, 10:45:25 am
content: Hi,Sorry for not being clear:HSD = High side driverExample:http://www.st.com/content/ccc/resource/technical/document/datasheet/cd/1f/d3/43/b8/2d/48/0b/DM00157127.pdf/files/DM00157127.pdf/jcr:content/translations/en.DM00157127.pdf

author: Rerouter
author_rank: Super Contributor
timestamp: June 28, 2016, 10:49:04 am
content: The first unless your using them in parrellel, in which case your equivilent resistance would be 140/4, or 35 milli ohm,

author: samnmax
author_rank: Regular Contributor
timestamp: June 28, 2016, 10:54:38 am
content: The datasheet specifies 140mOhm RDSonper channel, so it should be 4*0.14W = 0.56WHowever, take into account that the given RDSon is at 25°C, it is 280mOhm at 150°C, so you should probably take a more conservative number depending on the temperature reached on your application.

author: tszaboo
author_rank: Super Contributor
timestamp: June 28, 2016, 11:48:10 am
content: As they said. I would calculate with worst case Rds and 1.5x nominal current. This package will be good with some 2W of dissipation if you have a ground plane and enough space to dissipate it.

author: halexa
author_rank: Regular Contributor
timestamp: June 28, 2016, 12:10:19 pm
content: Hi,Thx for all the good advices.
Power connector for a 80's Quasar Portable Color TV - Page 1
Forum section: electronics / projects

author: ledtester
author_rank: Super Contributor
timestamp: April 06, 2018, 10:18:34 pm
content: I have a Quasar portable color TV from the mid-80s, and I'm trying to determine the pinout of the power connector.It can run on either 120 VAC (0.9 A) or 12 VDC (3.5 A).There are 5 pins on the power connector:Code:Pin Color1 Blue Mains Live ???2 Yellow Mains Neutral ???3 Red +12V ???4 --- Not Connected5 Orange Chassis GND / Mains Ground / DC Ground ???Pin 5 (Orange) is definitely connected to the chassis. The function of the other pins I have surmised based on the their connection to the power supply section (see the next post.)(Edit Switched guesses for Mains Live and Neutral pins.)

author: ledtester
author_rank: Super Contributor
timestamp: April 06, 2018, 10:24:24 pm
content: (edit: switched Mains Live and Neutral guesses)Here is a pic of the power supply section.I've highlighted the areas of the board which are connected to the power pins (with the box whose border is the same color as the wire connected to the pin.)Code:Pin Color1 Blue Mains Live ???2 Yellow Mains Neutral ???3 Red +12V ???4 --- Not Connected5 Orange Chassis GND / Mains Ground / DC Ground ???

author: ledtester
author_rank: Super Contributor
timestamp: April 06, 2018, 10:31:06 pm
content: The big question I have is whether it seems reasonable that the chassis would be the Mains Earth when powered via AC and GND when powered by DC.
Power consumption of chip on glass display - Page 1
Forum section: electronics / projects

author: Aggressive_Doughnut
author_rank: Contributor
timestamp: October 03, 2019, 12:26:46 pm
content: I was thinking about putting together a little project that would include a custom cog display in the neighborhood of 8cm x 16cm. I want it to be battery powered, which I thought wouldn't be a problem. With the mcu design I have I am seeing a very low average current consumption, less than 10uA (not a very intensive project). However I saw an estimate for custom displays that said to expect ~2uA per cm^2, which would be around .3mA. At four AA batteries (two series in parallel) you would be hard pressed to get a full year of service out of that. The thing is, I have a desk clock with similar dimensions that has been running for over two years now on the same amount of battery.So is that estimate right and my desk clock just happens to have the best batteries in the batch?

author: amyk
author_rank: Super Contributor
timestamp: October 03, 2019, 09:57:54 pm
content: Per cm^2... of active electrode area.
Power Control of Heating Elements - Page 1
Forum section: electronics / projects

author: Regius
author_rank: Newbie
timestamp: January 24, 2020, 09:47:15 am
content: Hi,I want to control the power of mains voltage heating elements with arduino. The total power of the heating elements is 12kW.At first i decided to make a three phase SSR with optrons and TRIACs because it is cheaper but now i think to skip this part and directly buy Commercial 3Phase SSR - at least it is designed professionally.I'm currently looking at this SSRhttps://www.tme.eu/Document/5bcacf8879a7a0f54111a99faa335ecc/SR3-series.pdfwith Zero Cross Turn-On.With rough calculations the load current will be 12 000W / 220V = 55A or ~19A per phase - connected in Y configuration.1. My first question is if the given rated Amps are for the whole SSR or for 1 phase (1 triac)?I suppose the given Amps are the total load current because otherwise it would be written "load current per phase" ... or something like that in the datasheet.2. Is it a problem to control it directly from the arduino pin without any additional components?I see the input of the SSR is into an optron so there will be galvanic isolation between the arduino and the power circuit.Arduino output is 5V which is in the 4-30VDC limit of the SSR Input.3. The arduino will be about 3-4m away from the SSR.Is it a problem for the 5V control signal from arduino?4. What control interval (On/Off) will be OK?I'm thinking of 1 second interval. e.g. 10% power = 0.1s on / 0.9s off or 90% power = 0.9 on / 0.1s offMaybe to increase it? But lower than that i think won't be ok because the zero cross turn-on of the optron is not synchronized with the arduino output signal.I apologize if some of the questions seems stupid to you.I appreciate every answers / suggestions.

author: beanflying
author_rank: Super Contributor
timestamp: January 24, 2020, 10:04:02 am
content: I am running a small Electric Coffee Roaster (3.5kW) off a glorified Arduino and software via a 40A SSR. There is a few problems with the Arduino PWM in that it doesn't like being run slowly and certainly wouldn't allow the use of mechanical switches or contactors.So part of the software/library was written into a slow PWMhttps://github.com/greencardigan/TC4-shieldgreen cardigan is a member here but not that active. He is selling the TC4 shield on Tindiehttps://www.tindie.com/products/greencardigan/tc4-arduino-shield-v602/Some of the original board info is herehttp://www.mlgp-llc.com/arduino/public/arduino-pcb.htmlStart here with some reading might help you along the way.Optical Isolation is a MUST !!!

author: Regius
author_rank: Newbie
timestamp: January 24, 2020, 01:02:27 pm
content: I just use simple piece of code with a timer and counter which is turning on and off any of the outputs of the Micro controller. This is not okay for dimming a lamp but for the heater i don't think it will be a problem. I will read more about this slow PWM to understand how exactly it's controlling the SSR.
Power correction application - Page 1
Forum section: electronics / projects

author: calexanian
author_rank: Super Contributor
timestamp: January 01, 2014, 05:14:08 am
content: While working on something the other day I came up with an application that got me thinking. I have a DC permanent magnet motor that runs off of a car battery. Its actually a bilge pump in this application but that is not critical for this exercise. Ignoring varying load on the motor etc lets assume its speed is voltage Dependant. As my battery dies the speed of the motor will change as well, additionally I may want to run the motor at a lower voltage in a regulated fashion for a lower speed. As well as all this as the battery dies the voltage may fall below where I want it. This motor has a stall current of 10 amps, and therefore a startup current of 10 amps. I have designed buck converters, and I have designed boost converters. Has anybody ever encountered or designed one that will seamlessly do both and give a linear adjustable voltage range? My mind went to a boost converter, followed by a switching regulator. Yea that would work, but there has to be a more efficient way that two switching circuits in series. Any thoughts?

author: Rerouter
author_rank: Super Contributor
timestamp: January 01, 2014, 08:36:54 am
content: sepic converter?

author: Kremmen
author_rank: Super Contributor
timestamp: January 01, 2014, 02:56:04 pm
content: Sepic or buck-boost.

author: nctnico
author_rank: Super Contributor
timestamp: January 01, 2014, 03:34:39 pm
content: Just PWM it at 1kHz or so with a reasonable sized MOSFET. I wouldn't draw more current from a battery when it is empty. You'll wreck the battery. If you want to increase the voltage there is a nice picture of a motor drive in the Prius teardown report:http://www.osti.gov/bridge/purl.cover.jsp?purl=/890029-WIfqPO/

author: calexanian
author_rank: Super Contributor
timestamp: January 01, 2014, 05:26:56 pm
content: Quote from: Rerouter on January 01, 2014, 08:36:54 amThere we go. Thanks.
Power design for new project - Page 1
Forum section: electronics / projects

author: btfdev
author_rank: Contributor
timestamp: July 26, 2012, 02:39:38 pm
content: Hi all,Brain storming the power design for a new project.We are working on a design that uses both 12V and 5V DC when powered on. The 12V powers a light bulb for illumination and 5V powers internal circuitry and micro-controller. We also looked at the following:1. Cheap Chinese made 12VDC 1A wall wart may be used to power this product2. A step-down switch mode regular has been selected to provide a 5VWhat is the best practice for power design in this subject?1. Overall circuit protection?2. Do we need 12VDC protection for the light blub?Thanks in advance. BTFDev

author: SeanB
author_rank: Super Contributor
timestamp: July 26, 2012, 03:19:07 pm
content: Why not use a few white LED's in place of the lamp? It will save power, and you can just use a resistor to do the current limiting. You will need power protection in any case, so use the 12V supply and add protection to it, it will do both rails at the same time, and you can use series resistance before the overvoltage protection to increase the protection level, and using a fusible resistor adds a dual function in as well of surge limiting and protection.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: July 26, 2012, 04:13:57 pm
content: Why bother to add protection for the lamp?Just add a bit of protection for the DC converter to protect it against reverse polarity and spikes, and leave the rest to the protection of the power supply.Make sure to validate the chinese power supply before you start selling your project, safety and quality can vary bigtime.Fromhttps://www.youtube.com/user/mikeselectricstuff;
Power Design TP325, Digital Meter Installation - Page 1
Forum section: electronics / projects

author: amosborne
author_rank: Contributor
timestamp: July 06, 2021, 02:37:29 pm
content: Hello all, I wanted to share a link to a small electrical project I recently completed.Overall WriteupDemo VideoSchematicI had purchased an old Power Designs TP325 off Ebay and found that the third channel was not operational. After fixing the power supply itself (a wirewound resistor in the error amplifier startup circuit was failed open), I realized the front panel meter was toast. Rather than buying a new meter I decided to put together my own digital meter, soldered onto protoboards and jammed into place to maintain the wires-everywhere internal aesthetic.Other than a silly part selection in the 7-segment display I used, I would say the most challenging piece was programming the MSP430 as this was a new experience for me.

author: amosborne
author_rank: Contributor
timestamp: July 06, 2021, 02:47:20 pm
content: I can't seem to get pictures to show up on the forum- you can see them at the top of the writeup if you're interested.
Power Designs 6050C Display Mod - Page 1
Forum section: electronics / projects

author: idpromnut
author_rank: Unknown
timestamp: October 23, 2014, 04:47:31 am
content: Hi! After working with my PDI 6050C for a while, the size of the 7-segment display kinda bugs me. If you contrast it with the display in the 6050D, it is about 20-30% smaller than the 6050D's display. So I decided to build a "drop-in" replacement display board, and here it is with obligatory pictures! If anyone is at all interested in this mod, I'd be willing to mail them a PCB. There was a slight screw up in my schematic which flipped the A & B segments, so if anyone is interested I'll run a set of updated boards.Cheers!

author: robrenz
author_rank: Super Contributor
timestamp: November 19, 2014, 12:41:51 pm
content: Very nicely done!

author: idpromnut
author_rank: Unknown
timestamp: November 19, 2014, 01:23:31 pm
content: Quote from: robrenz on November 19, 2014, 12:41:51 pmThanks! I'm not very good with restorations yet, but this seemed to easy to pass up, and at the same time I like to think that the PDI guys would have done the same kind of thing had they been able to (in fact they must have, since they released the 6050D with the larger LED display later).

author: timb
author_rank: Super Contributor
timestamp: November 19, 2014, 01:25:45 pm
content: Very nicely done! Looks even better than the 6050D IMO.Sent from my Tablet

author: idpromnut
author_rank: Unknown
timestamp: November 19, 2014, 01:28:51 pm
content: Quote from: timb on November 19, 2014, 01:25:45 pmThe segments are a little too orange (I like the deep red of the 6050D and the original 6050C displays). But in terms of size, bigger is definitely easier to see!
Power dissipated on a die at the junction between FEOL and BEOL - Page 1
Forum section: electronics / projects

author: paop
author_rank: Newbie
timestamp: November 03, 2023, 03:03:10 pm
content: Hello.I have a logic die that has a junction between two silicon+FEOL and BEOL layers. In the silicon+FEOL layer, I have two TSVS (TSV1 and TSV2) which terminate right at the junction. There are no other connectors. I also have the total dissipated power in the junction (25W) (See the attached image)1) At the areas of the junction close to TSV1 and TSV2 (A, C), is the power dissipated greater or less than other areas (B, for example) ?2) Is there a way to calculate an approx value of the dissipated power at A and C, based on the above total dissipated power ? I can also provide TSV's areas and thickness, their thermal conductivity, as well as the SILICON + FEOL and BEOL thermal conductivities, thickness, width and height and thickness.Thanks
Power Dissipation in Current Regulator. - Page 1
Forum section: electronics / projects

author: fc3000
author_rank: Regular Contributor
timestamp: February 13, 2022, 06:46:00 pm
content: Hi all.I have an LM317 as a voltage regular followed by another LM317 set as a current regulator.If the power dissipation in the voltage regulator is Vin-Vout x I, what the power dissipation in the current regulator?Is it Vref x I ?RegardsFrancesco C

author: Gyro
author_rank: Super Contributor
timestamp: February 13, 2022, 07:03:16 pm
content: No, it's a bit higher, it's still calculated from Vin-Vout, but that differential is thedropoutvoltage spec of the LM317. Depending on manufacturer, the datasheet may specify a maximum at a given current (it is current dependent), or you may have to approximate it from the typical dropout voltage curves later in the datasheet. It's normally around 2V at 1A.The voltage across the current sense resistor will be Vref (at limit).Remember that the current regulator LM317 dissipation will increase dramatically when it goes into current limit.BTW, it's more normal to put the current limit regulator before the voltage one, specifically because its dropout voltage will be current, temperature, etc, dependent.

author: fc3000
author_rank: Regular Contributor
timestamp: February 13, 2022, 08:31:11 pm
content: Thank you very much.I have learned something new today!RegardsFrancesco C
Power dissipation in op amp - Page 1
Forum section: electronics / projects

author: liquibyte
author_rank: Frequent Contributor
timestamp: October 20, 2015, 10:41:37 pm
content: I need a bit of help understanding the power dissipation calculation for the TLE214x op amps. In the datasheet we have the calculationPD = (TJ(max) ? TA)/?JAbut I'm not sure I'm reading things right. If I do this using the typical ambient of 25°C I get(150 – 25)/84.6 = 1.47754137116This can't be right is it? 1.4 W? Most of the op amp datasheets I've looked at have something like 150mW max for PD.

author: liquibyte
author_rank: Frequent Contributor
timestamp: October 20, 2015, 11:48:02 pm
content: So if I go worse case ambient, I still end up well within what I thought should be absolute max PD.(150 – 70)/84.6 = 0.94562647754180% = 0.756501182032I was getting about 150mW in my simulation and was thinking that I was too close to PD for comfort. If you look at the datasheet for an OP07 dip, max PD is 150mW with 80 being typical. The circuit the 2142 is in won't see anywhere near 70C and I'm well under 750mW so I think I'm good to go. Thanks for the help.

author: liquibyte
author_rank: Frequent Contributor
timestamp: October 21, 2015, 02:03:24 am
content: Well it's not like they actually give us a clue other than the equation. All I'm trying to figure out here is if I can dissipate 150mW with the CP package for the dual version. If not, I need to find a way to lower the load. I have some ideas but will have to work through them. If the devices can take it, I'll leave the circuit as is.

author: liquibyte
author_rank: Frequent Contributor
timestamp: October 21, 2015, 02:58:51 am
content: I was looking at this part of the TLE2141 datasheet.4. Maximum power dissipation is a function of TJ(max), ?JA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max) ? TA)/?JA. Operating at the absolute maximum TJ of 150°C can affect reliability.Do I understand you correctly, that we can use this equation on any op amp to determine allowable power dissipation?

author: liquibyte
author_rank: Frequent Contributor
timestamp: October 21, 2015, 04:53:12 pm
content: Quote from: AcHmed99 on October 21, 2015, 11:47:58 amThat's going in my bag of tricks. I appreciate the help. Thermal stuff always confuses me more than the rest of it for some reason.
power dissipation vs duty cycle. - Page 1
Forum section: electronics / projects

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: March 09, 2023, 04:15:37 am
content: If I apply a 50% duty cycle V volts on R, is the dissipation (V/2)²/R as the average voltage is half or V²/(2*R) as the power is averaged to half?

author: bdunham7
author_rank: Super Contributor
timestamp: March 09, 2023, 04:59:02 am
content: The latter. Instantaneous power is I2R or V2/R. You can average the power to get the...well, average power. If you want to figure the power as a simple function of V and R, you need Vrmsnot Vavg. For a 50% duty cycle with a top voltage of V and a bottom of 0, Vrmsequals (sqrt(V2/2) (literally the root of the mean of the square). Apply your power formula to that and R and it should all fall into place.
Power Electronics Design Guidance  - Page 1
Forum section: electronics / projects

author: ow19m
author_rank: Contributor
timestamp: April 20, 2022, 06:06:29 pm
content: Hello ,Can anyone recommend me someone , some site that can check and troubleshoot a design that I've created , I might have made mistakes and could damage my circuit , potentially my IGBT's , it's basically an Inverter , Any answers would be wonderful , also Is it possible I can get it verified from a Texas Instrument Team , I was reading through their forum and one technical team member was willing enough to help with someones design that he requested.Thanks

author: jonpaul
author_rank: Super Contributor
timestamp: April 21, 2022, 01:00:07 am
content: Hello bonjour it takes years of experience to design and debug power electronics.I wouldn't use advice from a forum or TI application engineer.A lot depends on the required specs, regulatory compliance, safetyVery different for one pc hobbyists vs 1000s production for consumers electronic.special test equipment and probes may be needed to debug.Finally a,360,VDC bus is LETHAL so danger and liability is involved.Bon courageJon

author: moffy
author_rank: Super Contributor
timestamp: April 21, 2022, 02:39:36 am
content: Power electronics is part design and part implementation, the physical implementation such as heatsinks, cable lengths and a world of such detail can be as important as the original design. There are quite a number of very competent engineers on this forum that can provide good advice, but at the end of the day you will be fully responsible for what you do. The best advice in designing and building something new is to take lots of small steps rather than a giant leap. Work your way up, if unfamiliar with a certain power design, work from low voltage/low power towards your goal, as your experience improves so should your ability and competency.
Power Factor Correction Stage in Power Supplies - Page 1
Forum section: electronics / projects

author: Inductive load
author_rank: Newbie
timestamp: November 14, 2019, 09:34:17 am
content: Hi, I am currently studying PFC circuits and there is something that is not clear for me, the output of a boost-PFC stage is usually specified with something like: Vout=400V, Iout=500mA. My question is, does this mean that the RMS of input current of the following stage, let's say a flyback converter, should not exceed 500mA ? this sounds wierd because I am sure RMS current of such converters could surpass this value in many power supply applications. Can any one help me understand this please ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 14, 2019, 12:42:07 pm
content: The output is DC.RMS is not very meaningful at DC. You would have to justify why you are using RMS in the first place.Tim

author: Inductive load
author_rank: Newbie
timestamp: November 14, 2019, 01:08:51 pm
content: Thanks for your reply,Actually I want to connect a PFC stage to a flyback converter, the primary side current of the converter is expressed with the RMS drain current: IdsRMS, and peak drain current : Idspeak.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 14, 2019, 01:31:29 pm
content: Quote from: Inductive load on November 14, 2019, 09:34:17 amJust multiply the two to get 200W, then you just have to make sure the load connected to it does not exceed that.

author: Inductive load
author_rank: Newbie
timestamp: November 14, 2019, 01:45:19 pm
content: Ok thanks I understand, but it is just not clear to me how the transformer transfers 200W max when 400V is applied across its primary inductor and let's say IdsRMS= 2A passes through it.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 14, 2019, 01:47:53 pm
content: How are you calculating Ids(rms)?Tim

author: Inductive load
author_rank: Newbie
timestamp: November 14, 2019, 02:08:23 pm
content: According to application note AN-4146 from "On semiconductor" (eq. 9):IdsRMS= sqrt(D/3) x IdspeakD is the duty cycle.you can see in the design example that they found IdsRMS= 1.73A (p 14)link:https://www.onsemi.com/pub/Collateral/AN-4146.pdf.pdf

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 14, 2019, 02:49:26 pm
content: Ah, in the transformer section.Yes, you need that much RMS current handling, at the AC frequency, in the output transformer.Tim
power factor correction + THD - Page 1
Forum section: electronics / projects

author: kubeek
author_rank: Contributor
timestamp: March 21, 2017, 11:18:30 am
content: I am designing a system for railway that consumes roughly 1kW from public mains power, and I am having trouble fining the relevant standards that it should fulfill. The main market will be Europe, but in the future it might go as well to the USA, asia or elsewhere.So far I found that according to IEC 61000-2-3:2014 the device either should comply with generic conditions from clause 6.2.1 (or if it does not meet this then user should ask the supply utility for permission to connect it, but that is not desirable)What I cannot find, is any mention of the limits for power factor. Is there some other standard that I am missing?Also, does anyone know how is the situation in the USA and elsewhere in the world?
Power Filter for a Generator - Page 1
Forum section: electronics / projects

author: my67nova
author_rank: Newbie
timestamp: October 28, 2018, 04:42:16 pm
content: Has anyone come up with a DIY way to clean up power from generator? I want to have nice clean power to run my expensive CNC machines when I run off grid. Gotta keep those angry pixies in line!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 28, 2018, 06:01:26 pm
content: If it's got a lot of harmonics, a low-pass, or series of notch filters, can help. Mind that a filter necessarily increases the mains impedance at the fundamental (intended) frequency (i.e., more change in voltage for a change in current, for any change: more droop under load, more peak overshoot when a load is suddenly switched off..).A ferroresonant transformer isn't much help, because although it will clean up harmonics and stabilize voltage, it won't stabilize frequency; in fact, the reason it works in the first place is because it's a frequency-dependent output, and mains frequency is normally so stable that it can be used as a reference. Unless your generator has a really good speed control, I'm guessing this isn't going to cut it.That leaves some kind of frequency converter, which basically means as much hardware as the generator is already (there are low-tech ways to change frequency, but they require a special motor-generator set), or rectifying it to DC and inverting it back to (clean) AC with a true-sine-wave inverter.You're much better off just replacing the power supplies in your CNC with wide-input types. Typical switching supplies do 90-250VAC and don't care about frequency, as long as it's not so slow that power drops out between cycles. Maybe it already uses them and you're fretting over nothing?Tim

author: David Hess
author_rank: Super Contributor
timestamp: October 31, 2018, 05:27:26 pm
content: I have a couple of online (double conversion) UPSes for exactly this application but I am not driving a big load like machinery with them. I have seen people use an online UPS to power just the electronics like the readouts while powering the motors directly. Maybe it would be possible to power everything except the spindle motor from an online UPS?

author: duak
author_rank: Super Contributor
timestamp: October 31, 2018, 06:40:58 pm
content: OP: would you be able to give us more info on the generator and CNC equipment and what you're trying to filter out? There's quite a range.Among other things, I work with industrial CNC stuff that runs off three phase power. Most of the power is used in the spindle and axis drives and the rest by the control, pumps and cooling fans. The sudden current draw when a spindle winds up or an axis rapids would load the generator down and might cause trouble. If so, as David points out, a UPS might be a good idea.Cheers,
Power fluctuation issue: Adding wireless remote to led flashlight - Page 1
Forum section: electronics / projects

author: Neurotox
author_rank: Newbie
timestamp: February 25, 2020, 05:41:21 am
content: Hello,I'm still a beginner and I think my problem is pretty obvious but I'm not sure what/where to look for. (english is not my first language)Projet:-Adding wireless connectivity to 10 led flashlight (for an effect during a show)Flashlight:-Taller cob work lighthttps://canadiantire.scene7.com/is/image/CanadianTire/0379911_1?defaultImage=image_na_EN&imageSet=CanadianTire/0379911_1?defaultImage=image_na_EN&id=JjOqF1&fmt=jpg&fit=constrain,1&wid=315&hei=340-power source: 3xAA-Led: "Sealed" Led panel ...-A on/off switch and a 0,82 ohm resistor in series with the Led panelConstraint:-Low budget-Almost no free space inside the flashlight-Power source: 3xAA batteriesActual concept:-ESP32 via BLE as emitter/receiver (working, still need some tweaking but working) (next step will be to pass from a dev board to a bare ESP32 chip)-LDO 3.3V as power source for ESP32 (working)-Using MOSFET to control the Led panel (working)Current issue:-The LED panel is flickering when ON (not ON/OFF, really just a small variation in the output light) I think is related to the power consumption of the ESP32.What I have try:-Using a bench power supply with courant set way over the requirement: working-Turning the MOSFET ON by applying 3.3V to the gate without an ESP32: working...-Using a different power source (another 3xAA/LDO) for ESP32: Working but not really praticable because of the space constraint-Using a CR2032 batterie for ESP32: not working, not enough current to turn ON the ESP32-Changing the resistor so the Led panel will consume less courant (1,5 ohm, 2,2 ohm, 2,7 ohm and 47 ohm), not working, same issue but with dimmed light-Adding capacitor in random place... not working visually but it reduce the electric noise when I check with an oscilloscopeLDO 3.3V: P5501TG (NCP5501DT33G)https://www.onsemi.com/pub/Collateral/NCP5500-D.PDFMOSFET (will probably change): RFP30N06LEhttps://www.sparkfun.com/datasheets/Components/General/RFP30N06LE.pdfESP32 board (just for dev): Adafruit HUZZAH32 – ESP32 Breakout Boardhttps://www.adafruit.com/product/4172Any suggestion ?Thanks in advance!
Power General dc/dc modules from the 1970's - Page 1
Forum section: electronics / projects

author: trobbins
author_rank: Frequent Contributor
timestamp: February 09, 2022, 02:55:20 am
content: Has anyone come across any product data for the range of dc/dc converter modules made by Power General (Unitrode subsidiary) back in the 1970's ? These are fully enclosed, pcb mount modules. I have some Model 826 items with 5Vdc in and +/-15Vdc out (+/-190mA), so 5.7W output max. I have some Analog Devices 940 dc/dc modules of very similar capability, and have found a basic datasheet for them.Photo of similar module as reference:

author: trobbins
author_rank: Frequent Contributor
timestamp: February 09, 2022, 11:36:49 am
content: I just checked the datecodes on two modules and they are likely circa 1985 - oops.
power handling MOSFET - Page 1
Forum section: electronics / projects

author: ranganatennakoon
author_rank: Contributor
timestamp: May 13, 2021, 07:34:17 am
content: What SMD mosfet did you use for 5A 24V 120W power handling ?the Mosfet should be like this :1) low cost2)easy to find3) SMDthanks!

author: Circlotron
author_rank: Super Contributor
timestamp: May 13, 2021, 07:43:56 am
content: Why do you need 120W power handling? Unless it is something like a series regulator in a power supply there must be something very wrong with the circuit. And it is a big job to dissipate 120W on a metal heatsink, so a SMD dissipating that heat to a PCB,Or do you mean the MOSFET will be supplying 120W to a load? More details needed.

author: ranganatennakoon
author_rank: Contributor
timestamp: May 13, 2021, 07:49:49 am
content: its ok, design looks like dummy loader, A heat sink can't do without knowing!Do you know the number of such a SMD Mosfet?

author: Mr Evil
author_rank: Regular Contributor
timestamp: May 19, 2021, 09:15:40 pm
content: Imagine that you have a transistor with a maximum junction temp of 150°C, and the ambient temperature is 30°C. That gives a maximum allowed temperature rise of 120°C. To stay within that while dissipating 120W, you need a junction-to-ambient thermal resistance of no more than 120°C/120W = 1°C/W.Considering that the junction-to-case thermal resistance of a large SMD package like TO-263 will probably be >1°C/W by itself, there is simply no way you can keep it cool with any amount of heatsinking.You will need multiple devices in parallel, or a non-SMD package.

author: peepeepoopoo
author_rank: Newbie
timestamp: May 20, 2021, 12:08:34 am
content: I recently had a need for almost exactly the same, and used a IPB017N10N5LF. It is preferable to use a mosfet designed for linear region operation, otherwise you risk localised thermal instability and runaway, and can't make full use of the device power dissipation. The junction-case thermal resistance of this TO-263 device is 0.25K/W. Of course a very hefty heat sink is required if you wish make full (313W rated power) use of it, but I believe 120W is comfortable enough. Of course you need a heat sink for this, copper pours aren't enough.

author: ranganatennakoon
author_rank: Contributor
timestamp: May 20, 2021, 10:46:14 am
content: THANKS !
Power Input for Dual Channel Power Supply - Page 1
Forum section: electronics / projects

author: dave_robinson_022
author_rank: Contributor
timestamp: June 26, 2021, 01:14:39 am
content: I am working on the input for a dual channel power supply using a 300VA Toroidal Transformer with 2 x 25V secondary windings rated at 6A eachhttps://docs.rs-online.com/cbfc/A700000006791802.pdfI have two seperate channel modules to control current and voltage and will likely use ADCs and DACs with a microcontroller to link both in UI.I will need both up to 50V and 12A for testing (but not at the same time!) I am therefore thinking of utilising the following circuit with a physical switch to change between series and parallel inputs (50v @ 6A and 25V @ 12A) which will be shared between the two modules in parallel. I will of course need to ensure (probably through software control?) that both outputs never exceed 300VA in whatever configuration.Does this seem like a reasonable solution or is there a better way to achieve this?

author: bob91343
author_rank: Super Contributor
timestamp: June 26, 2021, 01:48:50 am
content: Looks okay to me. Just make sure the switch doesn't short anything while switching. Break-before-make, that is.
Power Latch Circuit Leakage Problem - Page 1
Forum section: electronics / projects

author: andrey-gvrd
author_rank: Newbie
timestamp: September 14, 2015, 12:14:38 am
content: I'm trying out the latching power circuit design from EEVblog #262 and the problem I have with it is that it releases after a minute being off due to capacitor leakage (I don't really understand where the charge is leaking to). Is this a flawed design since it will eventually turn on since there will always be some amount of leakage in a real circuit?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 14, 2015, 12:55:15 am
content: Try Roff = 1G.

author: andrey-gvrd
author_rank: Newbie
timestamp: September 14, 2015, 02:06:52 am
content: Quote from: T3sl4co1l on September 14, 2015, 12:55:15 amThanks, that worked.