hybridfree/eevblog-posts huggingface dataset:
Adding Hysteresis to ADCMP380 Comparator - Page 1
Forum section: electronics / beginners

author: ElektronikLabor
author_rank: Regular Contributor
timestamp: August 31, 2024, 08:11:10 pm
content: Hi folks,while designing a small circuit I came across to a beginner problem that I find challenging:I found a low power comparatorADCMP380that I want to use in a coin cell powered circuit (CR2032) that should last at least 5y.That comparator has it's own reference voltage but unfortunately the non-inverting input is hardwired with it and there has no access to it; so I've got only the inverting input to work with.On the inverting input I've got a voltage that is slowly rising (RC). When the threshold is reached the capacitor discharges until a lower limit and the cycle begins again (duration ~5min).For that I need a hysteresis.How can I add a hysteresis to the input?According to the datasheet one need connect a resistor (R2) between the output and the lower end of the input voltage divider (see attached image).In my opinion if you do that you get an oscillator: when the input becomes low when you reach the threshold, the voltage on the inverting input drops which switches off the output.Can you explain to me how that should result in a hysteresis?Or is there a mistake in the datasheet?Thanks

author: xvr
author_rank: Frequent Contributor
timestamp: August 31, 2024, 08:54:58 pm
content: Output transistor will invert output signal, so negative input of comparator is effectively a positive one.

author: ElektronikLabor
author_rank: Regular Contributor
timestamp: September 02, 2024, 09:12:39 pm
content: Quote from: xvr on August 31, 2024, 08:54:58 pmHi, thanks for quick replyI still don't understand; although it's just a simple circuit I still can't figure out how that supposed to be a hysterersis.

author: xvr
author_rank: Frequent Contributor
timestamp: September 03, 2024, 09:11:34 am
content: When input voltage below threshold comparator output will be high and opened output transistor. Transistor in turn short output to ground.So low input produce low output. And vice versa. So feedback to this input will be positive.

author: PGPG
author_rank: Frequent Contributor
timestamp: September 03, 2024, 10:00:03 am
content: Quote from: ElektronikLabor on September 02, 2024, 09:12:39 pmAfter first xvr answer I supposed subject is closed.My be you don't know that hysteresis need not be done at not used by you input but can be done at input you are using.Just if when your inputs going up crosses the switching level and as a consequence signal seen at komparator input is (thanks to positive feedback) rapidly shifted more up than to reverse back the komparator state you have to go with your input more negative that the level at which previous state jump took place. So you get hysteresis.
Adding INA225 to LT Spice - Page 1
Forum section: electronics / beginners

author: TG91
author_rank: Newbie
timestamp: September 15, 2021, 12:27:01 pm
content: I'm trying to add INA225 model into LTspice, I have downloaded the model fromhttps://www.ti.com/product/INA225#design-development##design-tools-simulationNow when I try to simulate it within any circuit I get this screen, what it the cause of this? I have tried both spice models from TIs website.

author: TG91
author_rank: Newbie
timestamp: September 17, 2021, 09:03:43 am
content: Sorry for the bump, but I am running out of ideas

author: Ian.M
author_rank: Super Contributor
timestamp: September 17, 2021, 09:38:25 am
content: If you attach your LTspice SIM, more members will be likely to take a look at it. If you've customized any symbols, models or libraries for the sim, zip them up with the .asc file. Don't include any sim result files as they'll bloat the zip file. Otherwise just attach the .asc file.N.B. order of preference when choosing models for LTspice:LTspice specific > SPICE 3 > any other proprietary SPICE that has its own extensions to SPICE 3 syntax.PSPICE models can be a PITA to convert, but at least PSPICE is well documented.
Adding indicator light to curve tracer - Page 1
Forum section: electronics / beginners

author: akabek
author_rank: Contributor
timestamp: January 22, 2023, 12:21:33 am
content: I am building the ThaiKit curve tracer. It has 120v input with a transformer providing AC 15v-0v-15v to the power board and DC 15v-0v-15v to the curve tracer board. I have a 12v 20ma LED bulb I would like to use to show the unit is powered on. To power the 12v bulb with 15v source would I add a 100ohm resistor in line with the LED bulb tapped into the DC 15v and 0v connections on the curve tracer board?

author: themadhippy
author_rank: Super Contributor
timestamp: January 22, 2023, 12:27:49 am
content: Quote100 ohms is a bit low,you want to loose 3v at 20ma so 150 ohms,but maybe try a bit higher to be nice to the led

author: akabek
author_rank: Contributor
timestamp: January 22, 2023, 02:41:16 am
content: I had a 220 ohm on hand and it works great. Thank you.

author: coppercone2
author_rank: Super Contributor
timestamp: January 22, 2023, 03:50:38 am
content: if you can handle the power requirement, the best way to do this is to get a potentiometer, wire it to the circuit, and turn it on. See if you like how the bulb behaves, then measure it and put that resistor. That way you can dial it in perfectly. That is the best way to deal with visual things. For higher power things a rheostat is nice (if you have that), they are pretty cheap actually. Light bulb resistance changes so its hard to calculate based on measurements taken when they are turned off.

author: wasedadoc
author_rank: Super Contributor
timestamp: January 22, 2023, 06:30:20 am
content: Quote from: coppercone2 on January 22, 2023, 03:50:38 amThat is a valid comment for an incandescent lamp but the OP wishes to use a LED.

author: rstofer
author_rank: Super Contributor
timestamp: January 22, 2023, 06:11:14 pm
content: If you are going to use a potentiometer to tinker with resistance values, add an 150 ohm fixed series resistor such that the current can never go above 20 mA. Otherwise, when you turn the pot toward 0 ohms, you will flow excessive current. The pot probably needs to be 100 ohm maximum and even then you'll likely use less than half of the range.When you get what you like, measure the total of the pot and fixed resistor.If I were building the project, I would just pick 220 ohms and call it good. LEDs don't need to run at full current.
Adding LED's to show actual fault cause to a circuit question - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 13, 2016, 11:58:12 am
content: I have a working version of this circuit I built some time ago. Instead of the center tapped transformer I use two 50V, 40 or so Amp computer server switch mode power supplies in series, for a fully regulated 100V to the Class D FET's, and a separate linear regulated 12V DC supply for the rest of the circuitry.I have shown the state of the gates used for over current protection to the PA FET's, excess reflected power from the SWR bridge, and loss of the 272kHz input signal with the amplifier working normally, on an abridged schematic showing the amp in the form I am using it. I also attach the originator's build documentation, but note I deleted some early circuitry as I already had a suitable (Kenwood TS-590 1mW exciter at 136kHz), and a pre amp and frequency doubler to feed my abridged circuit at 272kHz.As it stands a single LED shows if the circuit has gone into fault mode, due to high reflected power, too much PA current, or no input signal. I am rebuilding the amp mechanically to give much easier access for maintenance and repair, and would like 3 separate LED's to show just which of these three faults tripped the amp.IC6 has a spare trio of input pins and an output pin, and IC1B has 3 dual inputs unused.Can anyone much cleverer than I see a way to have 3 separate LED's showing just which of the three possible fault states tripped the amp please?Finally, am I right in thinking that diode D3 is there to stop voltages above about 12V reaching the gate pin 13 of IC1B, if the SWR bridge got really excited with reflected power? If not, what is its function?Thanks.

author: strawberry
author_rank: Super Contributor
timestamp: November 14, 2016, 08:57:39 pm
content: How about mosfet driver with SD function like IR2184...simplest way is to use single microcontroller to hook all LED's and delay need, or drive LED with emiter folover from sensor directlyD3 no doubt.
Adding mounting holes to PCB and should they be grounded? - Page 1
Forum section: electronics / beginners

author: Ram80
author_rank: Contributor
timestamp: July 24, 2024, 12:01:48 am
content: I had a PCB designed on fivver but I forget to order mounting holes in the design but I should be able to add them myself ok.It looks like you just select the mounting hole footprint and select the diameter and add the hole to the PCB?Also wondering if the holes should be grounded?

author: Kim Christensen
author_rank: Super Contributor
timestamp: July 24, 2024, 12:31:56 am
content: Yup... You just add the mounting hole footprint. Either plated or not.Whether you use a plated hole and connect it to chassis ground, or use a unplated bare hole, depends upon the design.

author: thm_w
author_rank: Super Contributor
timestamp: July 24, 2024, 12:32:17 am
content: It completely depends on the design.If its just a hobby project probably the simpler choice would be to leave them unconnected.Wouldn't it be better to learn about this stuff instead of paying someone to do it for you?https://www.eevblog.com/forum/projects/enclosure-grounding-for-board-like-feathers3/https://www.eevblog.com/forum/beginners/_grounding_-metal-case-without-ground/https://www.eevblog.com/forum/projects/lets-talk-about-cable-shielding-and-pcb-gnd-layer/

author: JustMeHere
author_rank: Frequent Contributor
timestamp: July 24, 2024, 12:47:22 am
content: If you do ground your chasis to the PCB, it should be done at one point. If not, you run the risk of creating some horrible ground loopsJust use whatever hole tool your PCB software supports. Try to place the holes some standard measurement apart. For example, use two inches. This makes it easier to design the thing you are mounting to.https://www.sigcon.com/Pubs/news/7_02.htm

author: Ram80
author_rank: Contributor
timestamp: July 24, 2024, 12:51:05 am
content: Quote from: thm_w on July 24, 2024, 12:32:17 amYes but it's good to have a complete project done for learning.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: July 24, 2024, 02:04:44 am
content: To be honest, I wouldn't even plate the holes. There's not enough metal there to do much. It's copper. Not too strong. There's a risk that the threads on the screw can cut off a shaving, and that falling onto the board..
Adding multiple DC power sources - Page 1
Forum section: electronics / beginners

author: raff5184
author_rank: Regular Contributor
timestamp: December 07, 2021, 04:21:42 pm
content: Hi,what is the best (most energy efficient) way to add the powers from DC sources that have different voltages, at a fixed voltage value?I have a harvesting circuit with multiple rectifiers. Each rectifier provides a voltage (and power) more or less different from the others and it is not always the same. I want to sum all the DC powers. The voltages are in the order of 10-20V and the power that the rectifiers can source about 200-800mW.Also, the voltage at which I want to add up all the powers is fixed and the single rectified voltages are randomly higher or lower than this value.I did some tests, disregarding the "fixed" voltage level and tried to combine the powers by connecting the rectifiers in parallel on a resistive load. This doesn't work well, because only the rectifiers that have higher and comparable voltages (and powers) will add up, while I noticed that the sources with lower voltages don't contribute (even though they are capable of sourcing power when the other sources are off).Do I need a DC-DC converter at the output of each rectifier? Is only one DC-DC converter enough, meaning would it force all the voltages at the same level?Are there other simple ways to add DC powers (IC chips, simple circuits)? Even if they don't add at the fixed voltage level that I need them to combine, I can always use a DC converter after the sum

author: penfold
author_rank: Frequent Contributor
timestamp: December 07, 2021, 04:36:44 pm
content: I suppose the 'correct' way to do it would be to have one DC/DC per power input. It could then be a question of control if they are all feeding, say, a battery that is a relatively stiff voltage, but whether or not it is a problem would need some knowledge of the actual sources from which you are scavenging. A discontinuous current boost converter gives you some level of "power" control, which with something like a PV cell, having a very soft IV characteristic, allows you to vary the duty cycle and pick up on the maximum-power-point. In contrast, if you have a source that is a stiff voltage or current source, you would need to be able to determine the operating current to control the boost and ensure you're making the most of the source.You can connect the rectifiers in series, but then, similar to the voltage problem in parallel, the total output will be limited, by the lowest current. But again, there'll be solutions to it, but need to know the nature of the sources from which you're scavenging.

author: mawyatt
author_rank: Super Contributor
timestamp: December 07, 2021, 04:49:21 pm
content: Currents can be "wired ORed" together and the result is the sum. Convert the individual sources into currents with SMPS techniques, then add the outputs.Best,
adding noise to HV circuit - Page 1
Forum section: electronics / beginners

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: March 07, 2018, 04:35:09 pm
content: I am providing pulsed 600v DC to a 500khz tank oscillator which of course rings with a sine wave.I would like to make that sine wave "dirty" but do not want to make it into a saw-tooth or square wave.. simply "fuzzy" as if there were some vhf interference on it, but still a sine.I don't mind dropping some of the voltage, so I was wondering about putting a few reverse-biased zener diodes in the circuit for noise.Will that work? Any better ideas?

author: BrianHG
author_rank: Super Contributor
timestamp: March 07, 2018, 07:18:53 pm
content: Where is this 600khz pulse coming from?Are you generating it from an MCU?Are you trying to create a spread-spectrum noise in your oscillator to weaken it's effect on radio broadcasts?

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: March 07, 2018, 10:04:33 pm
content: The initial pulse is being provided by a 555 timer and amplified to the voltage needed.The Tank Oscillator takes the 600v pulse and then does it's job: Oscillating at 500kHz until losses cause it to stop (except there will be another pulse before then)I have attached 2 oscillagrams. You will see one is quite pure and the other is a bit dirtier. I want the dirtier version, possibly more dirty than the example I have given.
Adding pop filter to audio interface - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: October 20, 2018, 08:20:36 am
content: I have some usb audio interfaces hooked up to powered monitors and a system reboot always makes the monitors produce a loud electrical pop sound from the interface powering on. I wish to add some sort of modification to prevent these pops from being sent out to the speakers since I hate the speakers constantly getting hit with that. Is a relay what I need or something else?
Adding power LED to circuit - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: November 11, 2019, 07:11:46 am
content: Here is the circuit i am building..Should i put my LED between "Vin" and the point labeled "g"? I am thinking i should place a current limiting resistor after "Vin" and attach the LED to that. Is there anything wrong with that? This is going to be a small amplifier for a small microphone, so i'd rather not place the LED somewhere it might add needless noise to the circuit.

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: November 11, 2019, 07:30:05 am
content: If you add it between Vin and the Gate of the JFET you will load your microphone with the LED and clip the signal to the leds voltage, which is a big no no.Why don't you place it parallel to vdd with an apropriate sized resistor, if you want a power LED?If you want an activity LED, which I assume you want when you place it directly parallel to the "amplifiers" input, you would need an amplifier for the activity LED, (could be as simple as an comparator which toggles over a certain threshold) as the voltages from a standard microphone are very, very, very low and would never turn on the led.Also, I hope that your schematic is just an aproximation and not the real amplifier you are trying to build? If not think again about your design, this way it won't really work.
Adding regulated outputs - Page 1
Forum section: electronics / beginners

author: sk614
author_rank: Contributor
timestamp: July 25, 2016, 08:41:28 pm
content: I have two voltage regulator that convert to 3.3V. Is it even possible to add them together to get higher voltage?

author: Simon
author_rank: Unknown
timestamp: July 25, 2016, 08:42:29 pm
content: if they share the same ground, NO.

author: Zero999
author_rank: Super Contributor
timestamp: July 25, 2016, 09:03:46 pm
content: It depends on the regulator: Part number? Datasheet?

author: MosherIV
author_rank: Super Contributor
timestamp: July 25, 2016, 09:15:00 pm
content: QuoteSimple answer NO.You can do it with 1 voltage regulator:http://www.pcsilencioso.com/cpemma/diodes.htmlLook at the 'fixed regulator' section and how it is possible to raise the ground pin.It is also possible to do it with diodes and zener diodes.

author: Zero999
author_rank: Super Contributor
timestamp: July 25, 2016, 09:53:55 pm
content: Quote from: MosherIV on July 25, 2016, 09:15:00 pmYes. It can be done, so long as the load on the regulator use to lift ground pin is equal to or greater than the current taken by the other regulator.

author: sk614
author_rank: Contributor
timestamp: July 26, 2016, 08:56:23 pm
content: This is what I am using, a RF to DC convertor.http://www.powercastco.com/test566alpha/wp-content/uploads/2009/03/p2110b-datasheet-v12.pdfFor reason not possible, why is that?

author: Simon
author_rank: Unknown
timestamp: July 26, 2016, 09:01:50 pm
content: your input and output needs to be isolated otherwise when you put them in series you will connect the ground of one to the positive of the other that has the same ground, thus short circuiting one of the outputs. If they are fed from isolated inputs you can put them in series or if they use a transformer making the inputs isolated from the outputs.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: July 26, 2016, 09:06:02 pm
content: That device doesn't give you a continuous 3.3v. It uses the accumulated RF energy to charge a capacitor, then when it hits a set voltage it boosts it up to the voltage you want until the cap decays back down, and then it shuts off the output. Since the output is intermittent, you can't stack two of them and expect to get 6.6v. Most of the time you'd get 0, sometimes you'd get 3.3 from one device or the other, and very rarely (I'm assuming, I don't know your load or what kind of duty cycle you'd get from this device) you might get 6.6v.The two devices obviously couldn't share a ground, you'd need to stack one of their grounds on top of the other's Vout, and then take care of the myrid of problems associated with doing so (your two RF antennas wouldn't share a ground, your digital signals wouldn't share a ground, etc).
Adding series resistance to DVM probes - Page 1
Forum section: electronics / beginners

author: tojov
author_rank: Newbie
timestamp: January 25, 2024, 07:13:03 am
content: I was going through the book Troubleshooting Analog Circuits by Bob Pease. I came across a very interesting line in it's second chapter (Choosing the Right Equipment): "The most important reason to use a high-input-impedance DVM is because sometimes it's necessary to put 33 kOhm or 100 kOhm resistors in series with the probe, right near the circuit-under-test, to prevent the DVM's input capacitance from causing the circuit to oscillate". I couldn't really understand what he meant here. I haven't come across anyone using series resistance with voltmeter probes, and I also couldn't understand the part about input capacitance causing oscillations. Can anyone help me out on this one?NB: DVM - Digital Voltmeter

author: RoGeorge
author_rank: Super Contributor
timestamp: January 25, 2024, 10:33:27 am
content: The measuring probes + their wires have some parasitic capacitance, and some parasitic inductance, too (parasitic as in unwanted). Same, the DVM itself has some input capacitance. While measuring with the DVM, by connecting the DVM probes to your DUT (Device Under Test) all these parasitic inductance and capacitance become connected to your DUT, and that might make it unstable. If you add a resistor right at the tip of the probe, then the parasitic capacitance is isolated from your DUT (isolated in the sense of making the parasitic capacitance less influential, so not with the meaning of galvanic isolation).That advice is valid for very, very sensitive analog circuits only, and depends in what point you are measuring. Clip that 30-100k resistor to the tip of the DVM probe only if you notice that your DUT behaves very differently (or even starts to oscillate) when you measure it.It is not something one should worry about while casually probing voltages, but a trick to keep in mind for just in case.
Adding sleep function to a non-sleep Hakko stand - Page 1
Forum section: electronics / beginners

author: timgiles
author_rank: Regular Contributor
timestamp: November 08, 2015, 08:14:04 pm
content: Hi,I was wondering if anyone knows how the sleep function works on the Hakko FX-950 (and similar range). I recently bought a FX950 for a good price in Sweden but now having bought some tips dont really want to fork out yet another bunch of swedish krona on another stand just to get the sleep function to work. I have tried searching here and google but if the information is out there, my search skills tonight are sadly lacking.Thanks Timothy

author: Stupid Beard
author_rank: Regular Contributor
timestamp: November 08, 2015, 08:21:30 pm
content: I seem to recall reading somewhere that it used a magnet in the stand. Unfortunately, I have no idea where I read that or even if it's applicable to the FX950. So take that with a truckload of salt, but if you have a magnet to hand it should be pretty easy to verify.

author: wraper
author_rank: Unknown
timestamp: November 08, 2015, 08:50:49 pm
content: For sleep function you must connect a cable from the FH200-01 or FH200-02 stand to the station. If there is no connector on the back of the station, it is a counterfeit.

author: timgiles
author_rank: Regular Contributor
timestamp: November 08, 2015, 09:24:06 pm
content: Hi wraper.Unfortunately the 950 does not come with that stand. I don't want to buy another stand, just add the sleep sensor. So it is genuine, works a treat, etc... It was bought from the Swedish distributor. Half price for last two units.Anyway, thanks but hoping someone knows how it works.

author: helius
author_rank: Super Contributor
timestamp: November 08, 2015, 09:51:37 pm
content: I don't have one to test, but the simplest implementation would be either a normally-open or normally-closed reed switch, depending on if the socket in the main unit uses a bypass.

author: dadler
author_rank: Unknown
timestamp: November 08, 2015, 10:12:21 pm
content: It's just a microswitch.Just tested my unit: 3.5mm stereo trs, tip and ring open circuit when iron is out of the holder, and closed circuit when it is in the holder (sleep). E.g. When closed circuit (iron in holder), it puts the main unit in sleep mode.

author: amyk
author_rank: Super Contributor
timestamp: November 09, 2015, 01:04:26 am
content: Since it's so simple, it sounds like something that could even be added to all the 936 clones too - just a few components to force the control loop to a fixed lower temperature.
additional filtering on dps5015, how and why - Page 1
Forum section: electronics / beginners

author: lyma
author_rank: Newbie
timestamp: August 05, 2018, 03:58:58 pm
content: i bought this converter (DPS5015) so that i could power a few laptops from a 24V battery.People keep telling me that the output risks damaging those delicate equipment.i am not familiar with details like peak rms noise and ripple, so i can't really interpret the measures available publicly, and i am looking for constructive and educated advices.are there simple steps (soldering) that i can take to improve the output ?

author: Zero999
author_rank: Super Contributor
timestamp: August 05, 2018, 08:18:25 pm
content: I don't see why it would be a problem. If you're paranoid, add extra fusing and over-voltage protection to the output.

author: bloodhunter007
author_rank: Newbie
timestamp: July 30, 2019, 06:27:15 am
content: Quote from: lyma on August 05, 2018, 03:58:58 pmI don't know where you get this message, I have used DPS5015, it works well, and its VPP is about 100mvso you can consider
Additional scoping safety with GFI (Ground Fault Interrupter)? - Page 1
Forum section: electronics / beginners

author: ollihd
author_rank: Regular Contributor
timestamp: March 02, 2017, 09:21:50 pm
content: I have a question about oscilloscope safety. My scope is connected to a grounded power strip with surge protection. I scope with high voltage differential probes when the DUT is not floating. I mainly scope low voltage circuits, but occasionally some high voltage ones also.My question is: would I be adding additional safety to my way of working if i connect the power strip behind a GFI?

author: wraper
author_rank: Unknown
timestamp: March 02, 2017, 09:31:01 pm
content: You will get additional safety only if you power DUT through the GFI. Connecting or not connecting the scope itself, won't change anything.

author: ollihd
author_rank: Regular Contributor
timestamp: March 02, 2017, 09:32:59 pm
content: Thanks for the reply. Starting to make sense. DUT would automatically be behind the GFI since it draws from the same power strip.
Addressable LEDs - Page 1
Forum section: electronics / beginners

author: botcrusher
author_rank: Regular Contributor
timestamp: March 10, 2016, 03:49:28 am
content: As i understand it, the most common addressable LEDs use those lovely ws2182 chips. Slight problem: since at the end of the day, each led effectively contains 3*8bit registers, and the clock/data lines are one and the same, won't i run into an issue where I can't pump out all the lights at the same time? I need one microcontroler (preferrably an atmega328?) to control at minimum 10m of led strip (300 lamps, 3 bytes per lamp, 900 bytes per update, 30 updates per second...27000 bytes per second)10m happens to be the length of our stage rigging bars for no good reason...If using these self clocking three pin lights are out of the question, can anyone point me in the direction of how to drive these fast enough or help me with some of the veritable unicorn 4 wire (5v,dat,clk,gnd) strips i hear whispers of every now and then.

author: matseng
author_rank: Frequent Contributor
timestamp: March 10, 2016, 04:01:47 am
content: If you're more into using and creating the lightning patterns rather than tinkering with electronics and low level coding you might want to have a look athttps://github.com/scanlime/fadecandycontroller board for an excellent piece of hard- and firmware that will make life easer and prettier...

author: viperidae
author_rank: Frequent Contributor
timestamp: March 10, 2016, 06:11:58 am
content: About 5 seconds of google found FastLEDhttps://github.com/FastLED/FastLED/wiki/Parallel-OutputSupports 8 strips of WS2812 in parallel, so you're not driving 300 LED's serially, you're driving 37, 8 at a time.Edit: regardless, it only takes 10ms to write to a string of 300 WS2812's

author: tszaboo
author_rank: Super Contributor
timestamp: March 10, 2016, 12:07:03 pm
content: The way I understand it, those WS2818 chips are PITA to use, because of the timing. It is not an issue if the goal of the micro to drive those, otherwise you need interrupts. There is another type, APA102, which has clock input, so any* frequency bit banging is ok.Just my 0.02 EUR .

author: botcrusher
author_rank: Regular Contributor
timestamp: March 10, 2016, 01:57:58 pm
content: Fast led looks nice, but eh, slight issue. I can't for the life of me find how many i can bloody well drive at once XD

author: Dinsdale
author_rank: Regular Contributor
timestamp: March 10, 2016, 02:03:18 pm
content: It should take roughly 270mS out of every second to refresh your serial LEDs.(There is some "wiggle-room" in the timing, and it depends on the driver code what the exact timing will be).If this is too much time or not depends upon what else your code is doing (your time budget).Just be sure to use the right addresses.

author: botcrusher
author_rank: Regular Contributor
timestamp: March 10, 2016, 02:23:15 pm
content: Well, while the apa102c is very nice, It's incredibly costly compared to the ws chips. It would actually be significantly cheaper for me to buy an arduino pro mini clone for each 60leds (the amount used in the first fastLED tutorial) than to drive 30 apa102c LEDs...
Addressing negative spikes: rectifier + TVS diode? - Page 1
Forum section: electronics / beginners

author: kellogs
author_rank: Regular Contributor
timestamp: October 06, 2022, 01:19:31 pm
content: The rectifier diode:https://www.tme.eu/Document/e6d16d51cc343d73832bf32cc9d69d1f/p2500a.pdfQuoteTVS diode: any 1.5 - 5 kW diode should do I guessSay, for the ISO 7637 test pulse 1Quotewould a TVS diode provide most of this inrush IR current down to leakage level Ir current into the rectifier diode, protecting the rest of the circuit for the first, what should it be... 10 x 1500 ns ? or will the rest of the circuit (which I am trying to protect: linear voltage regulator + MCU) be the faster one to provide that current, and become damaged in the process?Thanks

author: kellogs
author_rank: Regular Contributor
timestamp: October 07, 2022, 02:53:13 pm
content: Or perhaps I should replace that TVS with a capacitor ?

author: thm_w
author_rank: Super Contributor
timestamp: October 07, 2022, 10:41:21 pm
content: Capacitor + TVS.You'll want one on the input of the regulator anyway.

author: kellogs
author_rank: Regular Contributor
timestamp: October 07, 2022, 10:51:59 pm
content: Ok, thanks, how much charge should the capacitor store, any other give aways ?

author: kellogs
author_rank: Regular Contributor
timestamp: October 09, 2022, 03:41:57 pm
content: How about 10nF ?Spreadsheet saysQuoteif IR goes from 1A to 0.25A in 1500ns i am going to go out on a limb and postulate that 12us will be enough to shut it down, with an average current of around 0.1AQuoteReasoning: in order for IR to go from 1A to some 10uA - I shall pick 15.26uA for a round value - a factor of 4^8 is required to divide initial 1A. That would make for 8 intervals of 1500 ns, since one such interval will reduce IR to a fourth.VRRM = 400V for my diode, I am aiming at 150V max with a rise time of 1us. That will make the average VR for the 12us interval some 140V, by just eyeballing it.Now, my cap will be charged at 12V, and for 0.1A over 12us -> Q = 1.2uC -> C = 1.2uC / (12V - -140V) =~ 7.9nF, so an 10nF cap, MLCC, ought to do the job (i.e. protect voltage regulator and parts downstream). Am I anywhere near reality ?
ADDS VPT2 Display help - Page 1
Forum section: electronics / beginners

author: brotherbrine
author_rank: Newbie
timestamp: January 17, 2024, 08:47:01 pm
content: TLDR: is it worth repairing an ADDS VPT2 Display?----------------------------------------------------------A buddy of mine does some salvage/scrapping of buildings before they’re demolished. Knowing I’m a mechanical keyboard enthusiast, he brought me an ADDS VPT A2 he stumbled upon. Gave it a once over and dusted it out and it powered up with a loud beep and blinking green cursor. I was stoked! I don’t have any vintage computers, but I was able to get it to display a login prompt over USB/serial from a Linux box. I thought it’d be super fun to have a monochrome terminal to access the Linux commandline. No keystrokes appeared on the screen, so I replaced all the foam and foil and a bad resistors and finally got it to display typed characters on the screen. I was not, however, able to get it to send those keystrokes back to the host device. Shortly thereafter, the display went dark. All this to say, I really enjoy the nostalgic aesthetic and feel of this terminal. I’m pretty handy when it comes to electronics, but I’m not comfortable dealing with CRT and the possibility of electrocution. Would it be worthwhile to have it serviced and utilize the existing CRT? If I do, what would it take to get 2 way communication going with Linux (Debian)? Or am I better off converting the keyboard to USB/Bluetooth and replacing the CRT with an LCD monitor?
ADE7816 Communication - Page 1
Forum section: electronics / beginners

author: ajit5wadekar
author_rank: Newbie
timestamp: June 10, 2015, 11:24:38 am
content: Hello Everyone,I am using ADE7816 with Atmega16 and I am able to achieve the communication using SPI. Can anyone help me with calibration of ADE7816.Please provide me with sample code if available.Regards,Ajit Wadekar

author: nickn4
author_rank: Contributor
timestamp: June 10, 2015, 06:55:05 pm
content: Welcome to the forums.I am not entirely sure what it is you need help with. but you might find this link usefull to youhttps://ez.analog.com/message/69299.i notice you posted on several forums when i googled on "ADE7816 SPI calibration".nick
ADG1438 with 0V, 0V, 5V supply - Page 1
Forum section: electronics / beginners

author: opampsmoker
author_rank: Regular Contributor
timestamp: December 01, 2020, 01:01:31 pm
content: Hi,We wish to use the ADG1438 with a single 5V supply. Is this OK?id Vdd = 5VGnd = GND (0V)Vss = GND (0V)ADG1438 multiplexorhttps://www.analog.com/media/en/technical-documentation/data-sheets/ADG1438_1439.pdf

author: KT88
author_rank: Frequent Contributor
timestamp: December 01, 2020, 02:23:50 pm
content: It is possible:CheersAndreas
ADG636 with 12V on pins S1A and S2A - Page 1
Forum section: electronics / beginners

author: LLee
author_rank: Newbie
timestamp: February 27, 2024, 08:33:36 am
content: Hello im pretty new with electronics and I want to integrate ADG636 into my project.Now I want to connect a battery of around 12V on pin S1A and S2A but I am not sure if this IC can handle this. On the "absolute maximum ratings" I can only find that power supply is maximum 13V. And that the analog and digital inputs are also something like 12V.Would the IC die when I connect the battery?

author: Andree Henkel
author_rank: Regular Contributor
timestamp: February 27, 2024, 11:09:51 am
content: the IC is intended for supply of 10V (+/-5V)13V is not intended normal operationoutput voltage of "12V" batterie easily exceeds 13V during charging / full, then your IC is likely dead
Adhesive for attaching thermocouples - Page 1
Forum section: electronics / beginners

author: fubar.gr
author_rank: Unknown
timestamp: August 01, 2023, 11:04:47 am
content: Hello,We want to take some temperature measurements on a PCB so we want to attach thermocouples on several spots. So far we used Kapton tape to attach them, but it doesn't always stick very well.Is there some kind of adhesive that could be used instead?

author: Slh
author_rank: Regular Contributor
timestamp: August 01, 2023, 11:47:33 am
content: I've used something like this (can't remember if it's the exact part number)https://www.vtech-smt.co.uk/loctite-4105-x-20gm-black-tak-kitin the past. Worked very well. It's a thick glue.Sometimes I used the glue to give the thermocouple an insulating layer before I glued it to whatever I was monitoring.
Adhesive to stick on a rubber pad - Page 1
Forum section: electronics / beginners

author: jayco242
author_rank: Contributor
timestamp: May 23, 2016, 10:46:39 pm
content: Hi,I will ask this in beginners as i am not sure where else this will go. I need to stick a large rubber pad onto the bottom of a few project boxes. Wikipedia says i need a removable adhesive. The pad would need to be removed to get at some screws. Obviously super glue is out of the question. does anybody know what I can use that is also accessible to general public? Gallon size or industrial quantities are too much.ThanksJason

author: Signal32
author_rank: Frequent Contributor
timestamp: May 23, 2016, 10:53:24 pm
content: Double sided tape / pads ?http://www.ebay.com/sch/i.html?_odkw=double+sided+tape+removable&_sop=12&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR11.TRC2.A0.H0.Xdouble+sided+tape+.TRS1&_nkw=double+sided+tape+&_sacat=0http://www.ebay.com/sch/i.html?_odkw=double+sided+tape&_sop=12&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xdouble+sided+pad.TRS0&_nkw=double+sided+pad&_sacat=0Depends how strong you need the bond to be.Or permanent glue some velcro on feet + case if you think you'll be accessing the screws all day longBut you're probably looking for the glue'y gel'y stuff that sticks but doesn't dry. I don't know the commercial name for that, I would be interested to find out.

author: Cerebus
author_rank: Super Contributor
timestamp: May 23, 2016, 11:07:20 pm
content: Neoprene cement. Look for the type used either for wetsuit manufacture/repair or shoe* manufacture/repair. Depending on the type of 'rubber' you have it might need the surface treating either with a specialist primer or passing through an open flame before gluing.*This type often goes under the name 'colle de cologne'.

author: IanB
author_rank: Super Contributor
timestamp: May 23, 2016, 11:47:41 pm
content: I would use something like this:http://multimedia.3m.com/mws/media/796078O/rubber-and-vinyl-80-spray-adhesive.pdf(Which is indeed neoprene cement.)I would punch holes in the rubber pad where the screws are.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: May 24, 2016, 02:21:35 am
content: 3M / Permatex Weatherstrip Adhesive. Available in yellow or black, at your car parts store.

author: houdini
author_rank: Regular Contributor
timestamp: May 25, 2016, 01:04:33 am
content: +1 for weatherstrip adhesive.

author: bitseeker
author_rank: Super Contributor
timestamp: May 25, 2016, 01:40:12 am
content: +1 for punching holes in the pad for easy access to the screws.
Adjacent Channel selection (ACS) - Page 1
Forum section: electronics / beginners

author: Yaa
author_rank: Newbie
timestamp: March 01, 2024, 03:44:52 am
content: i got a 2 way radio with a frequency 150Mhz, 12.5kHz channel spacing.Then there is 2 base station with different transmitting frequency.a) Base station A =150.05Mhz, Base Station B = 150.1Mhzb) Base Station A =150.05Mhz, Base station B = 150.08MhzWhich station most likely cause interference to my radio?-------------------------------------------per my answer is:b) Base Station A =150.05Mhz, Base station B = 150.08Mhzi calculate the interference +-(0.5*12.5kHz) for both combination.my radio = 149.99375/150.00625combination a)Base station A = 150.004375 / 150.05625Base Station B = 150.09375/150.10625combination b)Base station A = 150.004375 / 150.05625Base Station B = 150.07375 / 150.08625both combination not interfering my radio. However I choose combination b) due to the interference is the closest compare to combination a). Is it correct?

author: m k
author_rank: Super Contributor
timestamp: March 09, 2024, 02:01:26 pm
content: So 150.0125 is the next channel after 150.0000 channel.And 150.0500 channel is already sort of far away.In theory you can calculate many things, but in practice you must obey the reality.So if your current pick is bad you just pick another and leave the theory aside.Or find a disturbing station, go there and start nagging how their gear is faulty and is not obeying regulations.
Adjust current source via an fake logarithmic potentiometer? - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: August 12, 2020, 10:21:05 pm
content: A load is a simple LED and is dimmable, by adjusting a potentiometer or resistor.I need it to be adjusted by a logarithmic potentiometer but due to design and number of similar circuit would I need a logarithmic pot with 4 layers.So, thanks to you, did I find this link, describing a simple fake potentiometer:https://sound-au.com/project01.htmThat drawing is about the same as B.Is it possible to add B into circuit A, to act as the fake logarithmic potentiometer?

author: t1d
author_rank: Super Contributor
timestamp: August 15, 2020, 11:10:03 am
content: To make sure I understand... Your circuit is as follows... A 12v power source powers the positive pin of a typical LED. The LED is switched on and off, by a MOSFET on the ground pin. The LED is to be dimmed by a potentiometer, which is also on the ground pin. Correct?And, for whatever reason, you would need a 4 layer logarithmic pot to control additional items, at the same time and in the same way. Meaning, the schematic that you posted is just representative of what needs to be accomplished and is not the entire design, for the circuitry you wish to control. Correct?If so, it is very difficult for us to make suggestions, without some understanding of what else is involved... Even if you just describe it verbally. Therefore, please tell us what is going on.There are lots of ways to arrange an LED indicator light and dim it. Meaning, the pot can be before the LED. Or, the MOSFET (P-Channel) could be before the LED. So, the first thing to do is to consider what the limiting factor is that requires a four layer pot and to see if by rearranging the component order you can negate the problem. Also, the pot could be placed on the gate of the MOSFET.Maybe a transistor would be better for your application?Expand your thinking... What is common to all four parts of the circuit that you wish to control? How can you control this one common point, to effect all four parts of the circuit?

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 17, 2020, 05:04:30 pm
content: We can use pot with first cirquit (with Fet) but the first cirquit is intended for small milliampere currents. We need to use pot as rheostat with only two points.If you want large currents (tenths or hundreds of mA) then you need a MOSFET and an shunt (or long story short - something like electronic load). Or other type circuit - PWM type.
Adjust current with LM350 - Page 1
Forum section: electronics / beginners

author: gnlinuz
author_rank: Newbie
timestamp: September 17, 2014, 07:03:34 pm
content: Hello all, i am wandering how to adjust just current using LM350 (Not limiting). There are some schematics on the lm350 pdf file using a variable resistor at the output. I am newbie but i understand that all the current must flow through that pot, which i think is not a good idea (for 3A). Is there any other way to do it?? I hope i can drive the LM2576 to build an adjustable voltage - current power supply. Thanks all.

author: David Hess
author_rank: Super Contributor
timestamp: September 27, 2014, 04:07:03 pm
content: The LM350 is just a 3 amp version of an LM317 which is much more common so any circuit designs you find using the LM317 apply just as well to the LM350.QuoteYep. This works for low current fixed current regulators but not so well over a wide range unless you use a high power potentiometer.QuoteAdding a current regulator to the input or output of a switching regulator using just an LM350 is not going to work well at all. The way to go about this is to use separate external current and voltage control loops.The simplest adjustable current limit using an LM317 or LM350 looks something like the beginning part of this schematic:http://powersupply88.com/variable-power-supply-with-adjustable-current-limit.html/variable-power-supply-with-current-limitI would replace the JFET current regulator with a precision bipolar based current sink and drop the two diodes which are no longer needed (or replace them with a 1.25 volt shunt regulator) but that is the general idea. The current sink develops a voltage across the potentiometer which adds to the voltage across the current sense resistor as far as the regulator is concerned so it lowers its output so the voltage across the sense resistor drops which lowers the output current.
adjustable bench power supply - Page 1
Forum section: electronics / beginners

author: Daxxin
author_rank: Regular Contributor
timestamp: September 13, 2015, 05:29:07 am
content: Got new switching power supply with fixed 50v 20a output , planning to use this output to build adjustable power something like 0-40v and 10Asupply for my beginner lab , what problems i can have using that switching psu? any schematich to suggest?

author: lapm
author_rank: Frequent Contributor
timestamp: September 13, 2015, 08:19:01 am
content: Schematics, that's your first problem right there.. You should seriously first figure out how it works now. Then re-trace schematics of it and look up control chip. Se what that can do for you...Designing good quality switching power supply with high amperage is difficult. Do you really need 0-40 Volts range? I do some electronics as hobby and so far have not had use for anything over 15 Volts.Maybe you could keep this unit as is 50V/20amps and design add on unit you hook with cables that handles lower power functionality?40 Volts at 10A is 400 Watts of power. Be extremely careful what ever you build. That sort of power can kill, cause fire's, make things explode, etc...

author: Aodhan145
author_rank: Frequent Contributor
timestamp: September 13, 2015, 09:08:00 am
content: Too complicated with that high voltage as the only voltage in you need a pre regulator. Try find a nice transformer with taps and then get a negative rail as well.