hybridfree/eevblog-posts huggingface dataset:
A question about "Super Fast Recovery Rectifiers" - Page 1
Forum section: electronics / projects

author: Irukanji
author_rank: Contributor
timestamp: November 03, 2013, 11:29:59 pm
content: Anyway as the title states, I'm looking for some more information on how these work/can be used.I pulled a "F5LC20U" out of a computer power supply a long time ago, but it's sat dormant in my parts box until now(my interest in electronics has been rekindled). Looking at the side of the packaging, it appears to be 2 diodes mounted end to end(presumably output side facing inwards).Now that got my thinking; could you hook up 2 separate power supply modules(positive rails, I assume), and have them combine in this component? The idea being is there could be 2 separate 5V rails but if you ignore those 2 ports and plug straight into the middle port(assume this example has 3 ports), could you get 5V with increased amperage(or 10V with halved amperage, I forget which way it works). The 2 separate would work fine until load is placed on the middle port(assuming no connection in the others).I wonder if there is a reverse of this, 2 diodes facing away from each other?Just some noob theories, if anyone can enlighten me, that would be great. Worst case I'll probably just get some 1N4004's and try the idea anyway.Thanks

author: dannyf
author_rank: Super Contributor
timestamp: November 03, 2013, 11:34:36 pm
content: You can combine two 5v sources. However, load balancing can be a problem.QuoteYes in general.

author: kxenos
author_rank: Frequent Contributor
timestamp: November 03, 2013, 11:58:14 pm
content: Correct. You can have 2 power supplies for example with 5 volts and combine them. If the voltage drop across those diodes is exactly the same and the power supplies are exactly the same voltage then you would have exactly the same current drawn from each power supply. In other words you would have a perfect load balance. But since our world is not perfect and neither the diodes are, you have to expect a small imbalance. You have to remember though that the diodes have a small voltage drop (forward voltage drop in the datasheet). So if you have 5V from the power supplies and the diode voltage drop is 0.4V then you will have 4.6V output voltage. You would also have to consider the power dissipated in the diodes that would be the voltage drop * the current through the diode for each one.Generally, better load balancing is done with small value resistors but in that case you don't have protection if one of the 2 power supplies stops functioning.

author: minime72706
author_rank: Frequent Contributor
timestamp: November 04, 2013, 12:46:14 am
content: Quote from: dannyf on November 03, 2013, 11:34:36 pmLook at the BAT54 --- varieties include "BAT54" (one diode), BAT54A (common terminal is anode), BAT54C (common terminal is cathode), BAT54S (I imagine means "Series", which basically looks like your standard input protection diode scheme)
A question about a current sensing circuit - Page 1
Forum section: electronics / projects

author: ploutone
author_rank: Newbie
timestamp: May 29, 2017, 03:55:58 pm
content: Hello,While searching about how to accurately sense current in high side, i found this circuit that is very accurate and i simulated it.I found some problems:1. There is a negative feedback but the op amp is operating in linear mode ( the output vatietes between 1.2V and 3V )2. What is the role of the mosfet ?3. Why the mosfet is operating in linear mode even if we apply a Vgs> Vthresehold.I know that the voltage on the 200Ohm resistos is the same as Vshunt, and the output votlage is equal to : Vshunt*Rout/Rin.Thank you very much for your help

author: Dave
author_rank: Super Contributor
timestamp: May 29, 2017, 05:22:31 pm
content: 1. The whole point of negative feedback combined with high gain amplification is to have a circuit that behaves linearly (if the feedback is linear, of course). Positive feedback would give you sharp transitions (used for comparators, for example).2. The role of the MOSFET is to take the voltage (which could be more than 70V) and to provide a means of controlling the current flow.3. If you applied Vgs that was below the threshold, the transistor wouldn't conduct anything (well, leakage).

author: Marco
author_rank: Super Contributor
timestamp: May 29, 2017, 06:39:16 pm
content: Quote from: ploutone on May 29, 2017, 03:55:58 pmBecause it has a linear mode for Vgs > Vthreshold and it's driven in that mode

author: David Hess
author_rank: Super Contributor
timestamp: May 29, 2017, 10:32:56 pm
content: The configuration shown below using a p-channel FET is more common because it can operate at higher voltages without using a specialized operational amplifier. Note that a source follower does not invert the output signal so feedback goes to the inverting input. Linear Technology is showing off their LT6015 "Over-The-Top" operational amplifier in your example.The low gate leakage of a FET minimizes error. In the past, a Darlington transistor or something more complicated might have been used if this was important.
A question about Function Generators - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: September 13, 2013, 04:04:27 am
content: Hi chaps,I was recently given a 1978 HP / Agilent 2213A Function Generator.This thing supposedly gives up to 13Mhz, AM, FM and has 2 separate channels. It is a long way from my basic capacitor-based frequency playthings.So the question is this..."What is the source of the frequencies in a Function Gen' such as this?"I can't seem to find any clear details.Here's a link to the manual, if needed.http://circuitslab.case.edu/manuals/Hewlett_Packard_3312A_Function_Generator_Operating_and_Service_Manual.pdf

author: Unknown
author_rank: Unknown
timestamp: September 13, 2013, 04:53:13 am
content: See the theory of operations. A constant current source alternatingly charges and discharge a capacitor. Driving a constant current in a cap produces a ramp, so this produces a triangle wave. Changing frequency range changes the capacitance, the vernier changes the current.

author: BiOzZ
author_rank: Regular Contributor
timestamp: September 13, 2013, 07:20:55 am
content: A highly controlled VCO run by a highly regulated voltage and current reference that is compared to most likely a calibrated OCXOas ALM says it makes a triangle wave thats than shot threw a comparator than thats converted in to the frequency types you needat high frequencies (late MHZ to late GHZ) its fed threw one or more PLLs to multiply the frequency after the first stage ... look over athttps://www.youtube.com/user/TheSignalPathBlogone of there videos discribed it very well but i dont remember what one ... maybe this one

author: Unknown
author_rank: Unknown
timestamp: September 13, 2013, 12:15:29 pm
content: Quote from: alm on September 13, 2013, 04:53:13 amSo, when there is no frequency at all exiting Vp-p, yet still a D.C. voltage, variable by the Vernier, the problem should be one or more faulty capacitors or lack of constant current source?Then, what component would be this current source? Is this a VCO? Although I didn't see one in the schematic.Thanks for the input.
a Question about RC oscilicator（used Multisim ） - Page 1
Forum section: electronics / projects

author: China NewBoy
author_rank: Regular Contributor
timestamp: May 15, 2020, 05:34:02 am
content: i used Multisim to run this Circuit ，i wonder the reason of chanel A（the left polar of C1） is changing like this（+ 9 to -9 suddenly）
A question about switch mode controllers, mc34063 particularly - Page 1
Forum section: electronics / projects

author: crispytato
author_rank: Regular Contributor
timestamp: October 05, 2013, 08:43:12 am
content: Hi there everyone, I have a quick question regarding using an mc34063 and external pass transistor in a design of mine.Basically, the design is a portable unit, running off of a single 3.7v lithium cell. My intention is to have the ability to vary voltage on the fly, however I've run into a problem, regarding how I can get it to regulate both above and below the battery voltage using the same circuit.I only need around 2-6 volts out of the product, at 1-1.75 amps (it will be closer to 1 most of the time)I am aware of the necessity to up-rate components in the circuit. The accuracy of regulation is not hugely important to this application, nor is the smoothness of the supplyMy thought was, perhaps I could run the mc34063 in it's inverting configuration, to avoid needing to both step up and down. is there anything I need to consider in using this config? Would any particular configuration be more or less efficient?Perhaps someone could point me in the direction of a different regulator that'd suit my purpose better? My primary considerations are:1) BOM cost (including the costs of additional components, I'd be happy to use a more expensive part if it saved on other BOM costs)2) battery efficiency. I really don't want to get any worse than the 34063, better would make me a happy man.I hope someone can provide me with some useful info, thank you very much in advanceChris

author: dannyf
author_rank: Super Contributor
timestamp: October 05, 2013, 10:47:36 am
content: QuoteThat particular part does one thing for you and another against you: not terrible efficient but terrifically cheap.

author: Harvs
author_rank: Super Contributor
timestamp: October 05, 2013, 10:53:51 am
content: The "typical" modern configuration for this is to use a SEPIC converter, because your output can be above or below the input voltage, and positive.These were once a PITA because they typically require a coupled inductor. However, they have become a very common these days and there's a huge range available on the likes of Digikey for quite cheap.If you're interested the best bet would be to read one of the numerous app notes out there from the likes of LT or TI.
A question on SMPS Design... - Page 1
Forum section: electronics / projects

author: mtechmatt
author_rank: Regular Contributor
timestamp: October 09, 2013, 07:50:15 am
content: Probably a simple one but why do buck boost ICs which drive external mosfets to power the inductor, seem to have a current limit?For example, I need to generate 70V at around 10A, not continuous, I could fill caps, but why do they often state a limit current when everything that is 'current related' goes through my choice of FET, Inductor etc, and not through the little TSOP, or am I mistaken as to how they work? I thought they were just monitoring PWM drivers...If anyone could recommend a device I would appreciate it, but on top of that its more of a quest for understandingThanks,Matt

author: CodiJack
author_rank: Contributor
timestamp: October 09, 2013, 07:53:21 pm
content: Often in buck-boost topology, inductor „charging” current is limited by voltage applied to choke , inductance and time. No classical current limit like in a typical fly-buck topology with "cycle by cycle" current limit (transistor is off when current rises above a limit).Here you monitore current through out freewheeling diode only during “discharge” phase.Switch is on -> current ramps up to peak value-> no real current measurements (mosfet is on, diode is off).Switch is off -> current ramps down from peak value-> current measurements is taken (mosfet off, diode on).This way you get peak current through switching mosfet but little “delayed”.For example, have a look into:http://www.ti.com/lit/ds/symlink/lm5118.pdf
A question on uCurrent - Page 1
Forum section: electronics / projects

author: ang370
author_rank: Newbie
timestamp: March 24, 2015, 04:05:04 pm
content: Hi all,I have a noob question: in the uCurrent layout there are tracks that end on all four corners.You can see two of them in the attached image. In the bottom side B+ and -V are present while in upper side "Vout +" anche VGNDWhy has Dave placed them there?Thank you

author: jolshefsky
author_rank: Regular Contributor
timestamp: March 24, 2015, 04:21:04 pm
content: When he had the boards panelized, he included traces across the small bridges which ran to a test connector. That way he could test all 8(?) boards on a panel at once before even snapping/snipping them into the individual boards you see.

author: ang370
author_rank: Newbie
timestamp: March 25, 2015, 11:09:16 am
content: I see. Thank you.Out of curiosity, could those traces act as small antennas and increase the noise on the instruments?In that case which are the preventative measure used by Dave to reduce that effect?

author: Psi
author_rank: Super Contributor
timestamp: March 25, 2015, 11:11:59 am
content: In one of his videos about the ucurrent you can see the entire panel and he explains the traces.

author: TwisteR
author_rank: Newbie
timestamp: March 31, 2015, 02:47:12 pm
content: May I ask, what is the purpose of this thin trace in current path between J2 terminal and current sense resistors (see image attached)?Thanks in advance!

author: SeanB
author_rank: Super Contributor
timestamp: March 31, 2015, 05:48:19 pm
content: That is the "Oops I pooched it" trace, there to act as a poorly defined fuse that blows at around 3-10A to prevent the unit catching fire if you place it across a battery by accident. Repair with a 5A SMD fuse after you pop it.
A question regarding MC34063 and external switching - Page 1
Forum section: electronics / projects

author: crispytato
author_rank: Regular Contributor
timestamp: August 30, 2013, 02:15:42 pm
content: Hey there everyoneI'm currently working on a fairly high current, low voltage power supply, which runs from 1 cell Li Ion or Poly. I intend to use the mc34063 (in boost configuration) in PDIP-8 with a TIP41C external switch. Now I'm kinda confused about a few things with the chip, as I've never had success with implementing the 34063 external switch combo on my own breadboard to experiment with, even when I used the datasheet schematic to the T, it didn't properly regulate at all. That said, If someone has a complete schematic of the boost config with external switch, id greatly appreciate seeing it to work off of.I want breadboarding again to try again with new, better information, I just want to get a proper circuit for boost config w/ external npn switch, 3.7v input and variable output. now here's my most pressing question: is boost config able to also go below the input voltage, even slightly? I only want 3 volts out minimum from a battery at typically 3.9-3.3v under load. the range I want is 3 to 5 volts. It will need to provide this at 1A - 1.6A or so over the range (I will heatsink appropriately). I'm going to use 1n5822 as the Schottky, and a tip41c as switch unless someone could explain what else I need to do to use a MOSFET properly instead. I would guess that by having a lower RDS than the bjt transistor's resistance it could be more efficient.my apologies if my typing is crappy, I have band aids on 2 fingers from a cut while sharpinbing a knife, and I'm just recovering from a nerve injury in just on the other arm that pretty well paralysed the whole thing for a month! ridiculous, I know...PeaceChris
A Quick I2C Question - Page 1
Forum section: electronics / projects

author: German_EE
author_rank: Super Contributor
timestamp: November 26, 2015, 07:14:58 pm
content: A question for those who know more about I2C than me. Assuming a 100 KHz interface speed how many I2C writes can I do per millisecond? The receiving device is a memory chip so the limitation here is the bus speed.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: November 26, 2015, 07:27:39 pm
content: This also depends on the device. Reading from or writing to the "current" address is faster than a random access. But continued read/write is typically limited by the actual device (EEPROMs tend to have "pages" e.g of 64 bytes).Full random write access:START | 7BIT_DEV_ADR | 0(Write) | ACK(Slave) | 8BIT_ADR_HI | ACK(Slave) | 8BIT_ADR_LOW | ACK(Slave) [ 8BIT_DATA | ACK(Slave) ]xN | STOPCurrent address read:START | 7BIT_DEV_ADR | 1(Read) | ACK(Slave) | [ 8BIT_DATA | ACK(Master) ]xN | 8BIT_DATA | NACK(Master) | STOPIf you count START, STOP and ACK/NACK as one clock, you can calculate with the above information how much clocks you need to transfer N bytes of data.

author: Fungus
author_rank: Super Contributor
timestamp: November 26, 2015, 08:01:42 pm
content: Quote from: German_EE on November 26, 2015, 07:14:58 pmTo send one byte of data needs 9 clock cycles, so your maximum speed is slightly more than 11000 bytes/sec.But you also have to send extra data because you need to address the chip, set up the writing address, etc. The amount of extra data will depend on the memory chip.

author: German_EE
author_rank: Super Contributor
timestamp: November 26, 2015, 08:25:47 pm
content: I think I'm going to make it. The requirement is to send 8 writes in 5 milliseconds and the figures from Fungus indicate about 55 possible writes in the same period less address overhead

author: dannyf
author_rank: Super Contributor
timestamp: November 26, 2015, 08:34:47 pm
content: Quote100Kbps/9 bits per byte transmitted * 1ms = ?

author: German_EE
author_rank: Super Contributor
timestamp: November 26, 2015, 08:37:30 pm
content: That's the theory Dannyf, but with I2C there is a lot of overhead with start bits, stop bits, ACK signals and lots of other stuff. Hence my question.

author: Fungus
author_rank: Super Contributor
timestamp: November 27, 2015, 07:27:34 am
content: Quote from: German_EE on November 26, 2015, 08:25:47 pmShould work even if each write is 4 bytes total.(ie. I2C address, 16-bit chip-memory address, data byte)
A quick question on interpreting Absolute maximum rating in datasheets - Page 1
Forum section: electronics / projects

author: Cicada
author_rank: Regular Contributor
timestamp: July 08, 2016, 02:32:31 pm
content: HelloLook at the attached schematic Question.pdf.I am driving a MAX3485 (power from 3.3V rail) with a output from an Atmel ATMEGA8535 (power from a 5V rail). NO Current limiting resistor in series! My mistake.The circuit has being operational for a while now but I am concerned about long term stresses on the MAX3485 input.The attached datasheet for the MAX3485 shows in the "Absolute maximum ratings" section that the device can be powered with a rail up to 7V with maximum input voltages on the DI pin of up to 7V. Usually the maximum input voltage on an input pin (such as DI) is specified as VCC+?V as can be seen in the datasheet for the SN65HVD178 attached.Do the MAX3845 use a different protection mechanism on its input pins that permits a 7V input on its input pins even if it is power from a lower voltage rail? The SN65HVD178 datasheet is clear about the relationship between supply rail and maximum input voltage on a input with its VCC+0.3V spec. The datasheet for the MAX3485 is certainly not. I think this might be a gap in the datasheet specifications.Any comments are welcomed.Cicada

author: Andy Watson
author_rank: Super Contributor
timestamp: July 08, 2016, 02:45:31 pm
content: QuoteI would interpret that as meaning the the inputs are, by design, 5 volt tolerant.

author: MosherIV
author_rank: Super Contributor
timestamp: July 08, 2016, 02:49:24 pm
content: HiQuoteData sheets do use both ways to specify the absolute parameters for devices.QuoteTo answer your implied question " am I ok driving the Max3485, with supply of 3.3V, with 5V" - YesThe data sheet specifically states that the DI pins can with stand a Maximum of 7V, regardless of the supply voltage.

author: Cicada
author_rank: Regular Contributor
timestamp: July 08, 2016, 02:58:13 pm
content: Good.I think it settles it then. I accept that the MAX3485 datasheet means what it says. That the input pins can be driven with voltages that are within the 7V limit regardless of what the supply voltage to the devices is.Thanks for your answers MosherIV and Andy Watson.
A quick spin 'round my backplane and proto cards. 6502 + TMS9918 - Page 1
Forum section: electronics / projects

author: visrealm
author_rank: Contributor
timestamp: December 06, 2021, 12:16:55 am
content: I've had a number of people ask for a better look at the backplane and the cards. Here's a (very) quick tour of most of the cards (except the LCD card).Since the last post, I've also added a PS/2 keyboard, making a keyboard controller from a PIC16F MCU. My first time playing with a PIC MCU. 4 Stars. Would PIC again.

author: x86guru
author_rank: Regular Contributor
timestamp: December 07, 2021, 10:17:16 pm
content: That's cool. I built a completely custom desktop 6502 based computer around 26 years ago for fun. I added a 16-bit ISA bus with a IDE controller, VGA card, SoundBlaster card, and created a custom OS for it. Everything is bitbanged with four 6522's.

author: visrealm
author_rank: Contributor
timestamp: December 07, 2021, 11:40:20 pm
content: Wow. That's awesome.I haven't added a 6522 to my build yet. I plan to though - I'm mainly interested in the programmable timer and using it as an interrupt controller. Everything else I have is connected directly to the bus.

author: x86guru
author_rank: Regular Contributor
timestamp: December 08, 2021, 12:49:26 am
content: IIRC, the 6522/65c22 require the 6502's Phase2 clock. I assume you fan it out over your bus?

author: MarkF
author_rank: Super Contributor
timestamp: December 08, 2021, 02:02:40 am
content: I still have my (first computer) Apple ][ in its original box.It was a lot of fun at the time; but I think I'll leave it in the box.Started my HO model railroad computer interface on it.visrealm:I have done a lot of work with PIC16's and PIC18's.I'm using a pic18f2550 in my wireless throttles and a pic18f4620 in the main USB interface for the railroad.I just discovered the pic32mx170f256b that I'm having a play around with. The think what has attracted me most is the DMA capabilities. I haven't done any DMA work since doing assembly language on a PDP 11/55. Opps... Showing my age.Here is a link for some EE lectures at Cornell. Lots of good info even for other MCUs.https://www.youtube.com/playlist?list=PLKcjQ_UFkrd4z2qoFuJ1jtVhCSuxxCTpkand their ECE_4760 course:https://people.ece.cornell.edu/land/courses/ece4760/index.html

author: x86guru
author_rank: Regular Contributor
timestamp: December 08, 2021, 02:38:15 am
content: Quote from: MarkF on December 08, 2021, 02:02:40 amI used to have an Apple ][ (not the ][+. the original ][). Mine didn't have an auto-start rom so when you turned it on, it immediately entered the monitor. I used to press 6 then ctrl-p and enter to boot the floppy in slot 6. I saved up for 1 year on my paper route to get a used Corvus Systems 20-meg (8" winchester) out of the Computer Shopper want-ads back in the early 80's. I also had a JDR Microdevices 300 baud modem. I also used to call the BBS listings in the back of Computer Shopper. I eventually got a Hayes Micromodem ][ for my Apple ][ and wrote my own BBS which I ran for many years. Good timesI still remember Woz's hand written "Red" book that came with my Apple ][.
A random benchtop PSU idea - Page 1
Forum section: electronics / projects

author: TheCrazyRichard
author_rank: Contributor
timestamp: April 05, 2013, 01:09:39 pm
content: Hi!I've been bored in the school again, and then I suddenly got another crazy idea.What about combining a switchmode PSU as a first stage, with a linear PSU behind it?Since the switchmode ones are high efficiency, but also contain a lot of ripple, why not add a linear regulator there to get rid of the ripple there?So it might still be something like a mid-efficiency PSU with a smooth output, right?What do you think about it?I might actually implement it to my PSU when I get to building it...--Richard

author: kripton2035
author_rank: Super Contributor
timestamp: April 05, 2013, 01:23:55 pm
content: it has already been done here fr examplea switchmode psu standard followed by a regulator module.http://www.tuxgraphics.org/electronics/201005/bench-power-supply-v3.shtml

author: Ghydda
author_rank: Regular Contributor
timestamp: April 05, 2013, 02:02:05 pm
content: There is one caveat to that solution though.The open loop bandwidth of the linear regulator must be ludicrously high in order for the regulator to have a fighting chance of suppressing the ripple-noise.

author: smashedProton
author_rank: Frequent Contributor
timestamp: April 05, 2013, 02:45:44 pm
content: You can make the smps follow a couple of volts above the ldo. That Is a tracking prereregulator. Watch daves video

author: smashedProton
author_rank: Frequent Contributor
timestamp: April 05, 2013, 02:45:52 pm
content: You can make the smps follow a couple of volts above the ldo. That Is a tracking prereregulator. Watch daves video

author: C
author_rank: Super Contributor
timestamp: April 05, 2013, 03:57:33 pm
content: If noise is important, You could do a "gatling gun" type of smps where each noise pulse becomes smaller and a higher frequency.Why not use some active noise cancellation?For a lot of RFI filters you see a transformer where one winding is in the positive side and one winding is negative side to cancel noise.That transformer should also be a time delay.so add some anti-noise to the output of that transformer.So what is good and bad points of idea?C
A raspberry like a CNC - Page 1
Forum section: electronics / projects

author: Bill
author_rank: Contributor
timestamp: December 14, 2023, 02:24:31 pm
content: Hello everyone,Is there a way to configure a Raspberry as a CNC to test industrial speed controllers that use SSCNET communication (like Mitsubishi)?What will be the challenges I will have to do it?I appreciate any help you can provide.

author: ledtester
author_rank: Super Contributor
timestamp: December 14, 2023, 02:45:40 pm
content: I did a Google search and found these resources:- LinuxCNC talking SSCNET III/H to a Mitsubishi MR-J4-B servohttps://youtu.be/sp6gpIJhyCI- Network Servo Interface Adapters for LinuxCNChttp://yurtaev.com/-https://www.linuxcnc.org/
A really, really dodgy digital voltmeter + ammeter from Singapore - Page 1
Forum section: electronics / projects

author: Kamkut17
author_rank: Contributor
timestamp: June 27, 2016, 01:04:30 pm
content: A while back (like, 2 months or so) I asked about programming an LCD screen into being a voltmeter/ammeter, Some people said I should get one of those digital ones they sell on ebay from china. Decided to buy this:http://www.ebay.ie/itm/262455986278?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITThought it would come with some kind of wiring guide (dont know WHY I thought these chinese products would come with anything)but it didnt, so I did a bit of scavenging on the web to find a design, found thisThe problems I ran in with this one, was that there was 3 thick wires and 2 thin ones, while my one was opposite (colours were the same though). Well, no problem, just swap them around. Right? Wrong.I wired it to a regular lm317 voltage regulator circuit, and my lm317 went really hot, like, as if I shorted it out hot (hint).Decided to probe around with my continuity tester, and I found that the 2 thick red and black pins were shorted out. (Not only that, but the middle of the 3 pin connector was shorted right along with them).I didnt consult back to the seller, because quite frankly, I dont care about the 3 euro I spent on this thing, also, if you also bought this product (or a product quite like it) I would appreciate if you showed me how you wired it, as right now I have absolutely no clue as to how to go about this. Thanks for reading.

author: ProBang2
author_rank: Frequent Contributor
timestamp: June 27, 2016, 02:27:24 pm
content: Hello.Don´t trust everything from the Net...Hope, this helps:

author: Kamkut17
author_rank: Contributor
timestamp: June 27, 2016, 03:59:24 pm
content: All done and working, thank you!
A resource for product safety design rules/guidelines? - Page 1
Forum section: electronics / projects

author: Esquared
author_rank: Contributor
timestamp: August 21, 2020, 07:48:44 am
content: As a young player in the game (4th year EE student) I was wondering where you would, if there is any, documentation on how products should be constructed? It is easy to point out a knockoff usb charger as unsafe, but it is more difficult to say what is actually sound design. I've picked up on little things from watching Dave over the years teardown products where something was soldered but it should have been a crimped terminal etc. This being way outside the scope of a uni course I want to find a way to intuitively understand, what is safe? I would like to think that there is more to it than just friendly advice. If I'm asking the right question, but the answer is there isn't a source for this then I'm all ears for things to watch out for.

author: AndyC_772
author_rank: Super Contributor
timestamp: August 21, 2020, 08:49:09 am
content: Search "IEC 60950" as a good starting point.

author: TimNJ
author_rank: Super Contributor
timestamp: August 21, 2020, 02:09:27 pm
content: FYI, the successor to IEC60950 is IEC62368. There’s probably more information on the internet about IEC60950 though.I’ve found some of the IPC standards to be helpful. IPC9592B, which is “Requirements for Power Conversion Devices for the Computer and Telecommunications Industries”, is quite specific to my industry, but a lot of great gems about proper usage of components, deratings, etc. Actually quite practical.

author: Esquared
author_rank: Contributor
timestamp: August 22, 2020, 06:26:02 pm
content: Okay thank you! Will give those all a look
A safe, collapsible mount? - Page 1
Forum section: electronics / projects

author: rea5245
author_rank: Frequent Contributor
timestamp: November 21, 2020, 05:42:51 pm
content: Hi,I have a gadget - roughly the size and shape of a smartphone - that I want to mount to my stand-up jet ski. It needs to be held perpendicular to the jet ski's handle bars, but if I impact it, I want it to fold down. So I'm thinking of some sort of spring-loaded mechanism.I'm not even sure what to google for. Any ideas?Thank you.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 21, 2020, 06:37:04 pm
content: Beats me, I'd start here and work up to something that looks sturdierhttps://www.ebay.ca/itm/Bicycle-Bike-Mobile-Phone-Holder-Bracket-Mount-for-Handlebar-Handle-Bar-Scooter/333639468956
A Second  GIGATRON  can be your homebrew VGA output.   MONITOR  and. DE-BUG - Page 1
Forum section: electronics / projects

author: RJSV
author_rank: Super Contributor
timestamp: July 03, 2021, 03:27:03 am
content: Hello !For closely following (potentially messy) machine code there is nothing like a simple panel. Of course the micro-code test / run-stop, and various direct memory reads and writes. The ability to write, to low level memory is actually hazardous, random bad luck, and Murphy's law : but the example use could be for running alongside another VGA driving GIGATRON.Best thing is your normal running device can just, for example, play the fast scrolling racer video games, on usual GIGATRON.In a speculative mode: Nice to have, maybe 4 logic sensing and high impedance mini-clips for inputs to the bench development monitor driver (so you would simply have TWO wooden cases.So, the panel idea is old, from pre-IBM days, I imagine..In a 4 by 4 array, 0 - hexcode 15 can be entered.Button Functions:RUN. HALT. RDM. WRM. ( 2 buttons for memory)BRK. STEP. RDIN. WROUT4. 5. 6. 70. 1. 2. 3It can be loaded up with additional features, alarm timer, etc.
A short video of how I designed, built, and programmed an EEG machine. - Page 1
Forum section: electronics / projects

author: SolarSunrise
author_rank: Regular Contributor
timestamp: January 16, 2017, 09:05:57 pm
content: I decided to make a short video on an electronic project (homemade electroencephalogram) that I have worked on throughout high school for fun. I threw together some footage I have recorded over the years in under 2 minutes. It shows me going through PCB design, etching PCB's, soldering the components, programming, ... etc. etc.The video is not of the best quality, but I hope you find it somewhat interesting! Thanks.

author: Krampmeier
author_rank: Regular Contributor
timestamp: January 16, 2017, 09:42:07 pm
content: Thank you for sharing, this looks like a nice and pragmatic design, and the video is fun to watch (would still be entertaining if it was a tad more detailled)! Does that TI frontend chip have differential inputs? Did you check if your design complies with the IEC 60601?

author: SolarSunrise
author_rank: Regular Contributor
timestamp: January 16, 2017, 10:09:12 pm
content: Quote from: Krampmeier on January 16, 2017, 09:42:07 pmYup. The ADS1299 is fully differential delta sigma ADC. It is really top-notch for recording electrophysiological signals of any kind. I threw together this video for my non-tech friends so that's why there aren't a huge lot of engineering details. There is much more information in my Hackaday page if you want to know more about it. (link is in the video description)Concerning IEC 60601, my project is an absolute joke. I don't recommend anybody follow through with my design since it has no isolation whatsoever. This project was a fun proof-of-concept, hence why I haven't considered any medial/industrial standards. Although it is battery powered, it is still absolute crap in terms of safety.Works great though. I am currently working on active electrodes that do not require any electrode gel. However, schoolwork is getting in the way...
A simple Bluetooth footpedal - Page 1
Forum section: electronics / projects

author: Renate
author_rank: Super Contributor
timestamp: October 08, 2021, 11:44:02 pm
content: I've always had various footpedals from Infinity USB transcription triple pedals to iRig Blueboard to reverse engineered selfie clickers. I finally got around to actually making my own to deal with the various shortcomings, unreliable sleep timeouts, no wakeup, etc. I started with an M-Audio foot pedal SP-1, which now lists for $19. It's small, it's steel, that's about all that's going for it. So I made a few alterations.I replaced the simple wire contact switch with a microswitchRemoved the output cableGround down a post and glued in a dual AAA battery holderInstalled the Bluetooth circuit board (a perfboarded Cypress CYBLE-012011-00 castlelated module)Ground the nub of the power (formerly polarity) switch down to half its height so that the power wouldn't accidentally get turned on.Installed an LED in the back to indicate pairingCut an opening in the top of the pedal for the BluRays to escapeReplaced the original top tread with a thicker rubber one (because of the new hole)I'm really happy that this doesn't sleep at inconvenient times, that I can have it send reports on down and up or even add long press. I use this for playing guitar in the park and scrolling my music. You could use this for an ereader page turner. My next project is to retrofit my iRig Blueboard so that I don't need an app to translate the GATT to application commands.
A simple Geiger Counter - Page 1
Forum section: electronics / projects

author: globoy
author_rank: Frequent Contributor
timestamp: April 15, 2024, 07:12:58 pm
content: Even though I don't have any real reason to have one, ever since I was a kid I wanted a Geiger Counter. So, long after I was a kid, I finally made a simple one and have amused myself and family pointing out our radioactive dish and glassware. It's based around the LND712 tube (alpha-beta-gamma detection) with a 3D printed enclosure. Even has a 555 chipI don't suppose many people will copy my design since there is a bit of assembly but I put it up on githubhttps://github.com/danjulio/Geiger-Counter. The part that might be interesting to those who already have the high voltage circuit and a tube is the GUI display which runs on a super cheap ESP32 dev board ($8.33USD athttps://www.lilygo.cc/products/lilygo%C2%AE-ttgo-t-display-1-14-inch-lcd-esp32-control-board?variant=42159376466101).

author: shapirus
author_rank: Super Contributor
timestamp: April 15, 2024, 07:21:01 pm
content: Is it actually displaying reasonable numbers? 6.87 uSv/hr is about 40 times the normal background level. Was it measuring a nearby source of radioactivity when that photo was taken?

author: coppercone2
author_rank: Super Contributor
timestamp: April 15, 2024, 07:23:12 pm
content: i wanted to make caps that you can put on that style so you can put filters for different radiation. I think its possible to do IIRC

author: globoy
author_rank: Frequent Contributor
timestamp: April 15, 2024, 07:31:52 pm
content: @shaprius - yes, it was sitting next to a plate that has a radioactive glaze. Where I live, I get about 20 CPM background radiation. Using the 0.00833 CPM to uSv/Hr conversation factor I am using in this uncalibrated device that corresponds to around 0.17 uSv/hr.
A simplistic impedance/phase measuring board Modification. - Page 1
Forum section: electronics / projects

author: Qmavam
author_rank: Regular Contributor
timestamp: February 14, 2024, 03:51:53 pm
content: Years ago I worked measuring peizo transducers using a simple board with a few resistors and some curly Qs to hold the scope probes. The concept is to measure current by measure the input voltage and measure the current by measuring the Voltage across a current sense resistor. The sense resistor can be 1Ω, 10Ω, or 100Ω, depending on the load you are measuring. By knowing the input voltage and calculating the current from the voltage across the sense resistor, you can calculate the impedance of the load. The transducers were capacitive, so while watching the scope we would adjust a variable inductor until the phase angle between the voltage and the current was 0*. Take the voltage and current in the 0* phase to know the R of the transducer, then short the load and and measure the impedance of the inductor to find the impedance of the capacitance of the transducer. But, it can be used to measure all impedances. Depending on how well you build the board to eliminate parasitics the higher the frequency of accuracy. Note; accuracy is limited to scope readings, it is usable, and I have for 30+ years. I'll post a schematic, for others to ponder, note, in my picture I show a cap to adjust phase it can be swapped for an inductor.Now the question, I was measuring the input impedance of an amplifier at 1MHz, I wanted to keep the 50Ω drive impedance from the signal generator, so I was using a 1Ω current sense resistor, with an 8mV input, my current was too low to read on the 2mV scope scale. Leading me to want a (bypass 1X) , 10X, and 30X gain amplifier to raise the signal across the 1Ω resistor.Anyone have a amp flat from 20Hz to 2MHz that will run off either 3V, 7.4V or a 9V battery.I have always wanted to build Wenzels low noise Altoids box amp, and it may be a good choice if I can make the gain adjustable.http://techlib.com/electronics/audioamps.html#Curious%20New%20Amp(page down to the Altoids box picture)It has a gain of 100,Is there a way to make the gain of Wenzels amp switchable other than an attenuator, i.e make the gain switchable from 10X or 30X?Thanks, Mikek
A slight bit of an oops and software request - Page 1
Forum section: electronics / projects

author: joblessalex
author_rank: Contributor
timestamp: July 08, 2013, 05:07:56 am
content: I went out and bought myself a TV tuner for an SDR. Turns out it works fine for that. What I wanted then was the actual TV part. Well Windows thinks it's only good for UK and every other country in the book. Under US it won't budge. Is there anyone who has the US software so I can use this thing? I am assuming that it can be easily switched since everything is done from a direct data stream in software and nothing in hardware correct?Device:http://www.ebay.com/itm/140963305137?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

author: Paul Price
author_rank: Super Contributor
timestamp: July 08, 2013, 12:22:58 pm
content: There must be some other country in this world that uses the USA system on the list.

author: Bored@Work
author_rank: Super Contributor
timestamp: July 08, 2013, 12:52:25 pm
content: The US uses ATSC, not DVB-T. If I see it correctly the decoder in the stick you bought can only do DVB-T's COFDM and not ATSC's 8VSB modulation. It can also deliver the raw I/Q data stream, but you would need a rather powerful PC with a pure software 8VSB demodulator. I am not aware of one.
A Small Experiment - Part One - Page 1
Forum section: electronics / projects

author: German_EE
author_rank: Super Contributor
timestamp: November 17, 2019, 04:48:03 pm
content: After watching far too many posts by Big Clive I'm going to try an experiment. The 5 V supply for my desk lamp died this morning and there is no hope of recovery (send no flowers as it was a Viking funeral). To replace it I've ordered off EBay the cheapest 5 V 2 A supply I can find with a Euro plug, the lamp has no exposed metal parts so whatever happens nobody is going to die.The price, 2.29 Euro with free shipping from China.When it arrives, sometime between December 15 and January 15 I'll do a PAT test to see if it's safe, check the output on a scope to see if it's clean, then test it under load. That will be part two.Of course, if you can find a 5 V 2 A supply with one of your local plugs on for less than 2.29 Euro (which is pretty close to the same amount in USD) then please feel free to join in. Let's find out how low we can go and still get something that doesn't kill us.

author: magic
author_rank: Super Contributor
timestamp: November 17, 2019, 07:05:06 pm
content: Bonus if you stick a thermocouple inside and check thermals.Story time: I bought a $10 switchable voltage wall wart rated for 2.5A output. It has no secondary current sense, only primary side over power protection, set to 30W for the highest supported voltage of 12V. If I set lower voltage, it happily delivers more than the rated current. I got up to 4A at 5V.The secondary rectifier is a standard silicon diode in TO220. It unsoldered itself during that overload test and probably is rather marginal in normal operation too. At 2A we are talking some 1.5W inside a tiny plastic box.

author: German_EE
author_rank: Super Contributor
timestamp: November 18, 2019, 09:18:31 am
content: Thermal checks are on the TODO list. As an example of the Chinese way to do business the order was placed on Sunday afternoon German time and by 9pm the package had shipped, that's impressive.
A spreadsheet for finding specific resistor ratios - Page 1
Forum section: electronics / projects

author: RnDMonkey
author_rank: Newbie
timestamp: June 11, 2024, 07:32:53 pm
content: For my first post, I present my favorite spreadsheet I've ever made (in terms of how consistently I've used it over the years).This is a spreadsheet I made about 6 years ago for calculating precise resistor ratios for voltage regulators using standard E96 resistor values. As a side-benefit, it's a really convenient list of standard resistor values. I think it's pretty easy and useful.
A stable synthesized signal generator - Page 1
Forum section: electronics / projects

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: March 20, 2021, 06:25:18 am
content: Every time I want to tune up an old radio I have a hell of a time setting my only frequency source, an ailing Heathkit IG-102 RF generator to the frequency I want. I also love to see what I can build from my junk pile and also spend not much doing it. So I asked myself, self: "What do I want?" What I wanted most was frequency predictability and stability. And maybe a few other niceties. So here's what I did about it: (and don't beat me up too much about the mechanics)https://imgur.com/a/6HeF8Pw

author: djerickson
author_rank: Regular Contributor
timestamp: March 20, 2021, 03:07:31 pm
content: Great project, thanks for sharing it with us. I've thought of a similar generator myself, but you a) actually did it, with b) all the details implemented and working.Respect!Dave

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: March 22, 2021, 07:32:33 pm
content: Quote from: djerickson on March 20, 2021, 03:07:31 pmThanks for the kind words.

author: cheater
author_rank: Regular Contributor
timestamp: March 23, 2021, 04:14:20 pm
content: Absolutely love it. I wonder why the master oscillator was running low? Did you figure it out?

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: March 24, 2021, 12:28:20 am
content: Quote from: cheater on March 23, 2021, 04:14:20 pmNope. But its fine now.
A stupid question about C# and Visual Studio - Page 1
Forum section: electronics / projects

author: 97hilfel
author_rank: Regular Contributor
timestamp: May 16, 2016, 01:05:28 pm
content: Hello everybody,I don't know if this is the right place, but I am currently building my own 3D-Printer and I wante do write my own softwaren.So I started coding and came to the point where I came to a question:Everytime I start my Windows Forms application its different from they style i should be.its like it doesn't leave the space beteween the comboboxes, the 100 by 100px buttons arent exactly 100 by 100px (I have circular immages on them so I can see it).Does somebody know why?Felix

author: CM800
author_rank: Frequent Contributor
timestamp: May 16, 2016, 01:35:17 pm
content: Quote from: 97hilfel on May 16, 2016, 01:05:28 pmWould it be possible to show us some pictures and code?

author: 97hilfel
author_rank: Regular Contributor
timestamp: May 16, 2016, 02:09:57 pm
content: I use PNGs as Icons in the buttons.But I had that problem also without Images

author: elecman14
author_rank: Unknown
timestamp: May 16, 2016, 02:18:51 pm
content: You may want to look into placing your controls in a table layout panel control. If you dock the panel in the form (or another panel) and properly anchor the controls they will expand and contract if the user re-sizes the gui.If you are against using a table layout panel you should check your autoSize, and your growAndShrink properties on your buttons.Your text width may be causing your buttons to expand in width. You could test this by creating a grid of buttons with a single char in the visible text.If you really get stuck you can use the control.location and control.width to determine the actual location of the controls and see if you are getting any painting position weirdness.Good Luck.

author: Buriedcode
author_rank: Super Contributor
timestamp: May 16, 2016, 08:05:38 pm
content: The web has many examples of adding custom images/glyphs to controls on winforms. I would use wpf instead as xaml is handy in the future (that is if you're just starting out, even though its been depreciated). It also makes it easier, and makes more sense, when adding and manipulating custom controls at runtime.

author: 97hilfel
author_rank: Regular Contributor
timestamp: May 17, 2016, 04:32:34 am
content: I don't manipulate controld during runtime, exept from the enabling a disenabling of buttons and switching from a tab control tab to another.But Im going to try it.
A substitue for 32M x 8 Synchronous DRAM  - Page 1
Forum section: electronics / projects

author: stojke
author_rank: Regular Contributor
timestamp: December 05, 2018, 09:11:56 am
content: Hello, is it possible to substitute an Synchronous DRAM 32MX8 166MHz TSOPII 54PIN RAM Chip (NT5SV32M8CS-6K) with an for example P3V56S40ETP-G6? (16MX16)And why are 32Mx8 DRAM prices so much higher compared to others (even Chinese)?

author: dmills
author_rank: Super Contributor
timestamp: December 05, 2018, 10:02:43 am
content: Different number of address bits, so nope.It **Might** be possible to get clever with a 32M * 16 part, but it is not going to be pin compatible so you are looking at a board respin at the least, and some **Careful** reading of datasheets to check that you can make it work with only one byte lane in use.The 8 bit parts are expensive because nearly nobody bothers with them these days.Regards, Dan.