hybridfree/eevblog-posts huggingface dataset:
Constant Freq, Variable Duty - Page 1
Forum section: electronics / projects

author: chinook_eng
author_rank: Newbie
timestamp: October 24, 2019, 10:13:52 pm
content: Hello everyone, first time to the forum, but I need help!I'd like to design in hardware a static frequency variable duty PWM generator and running into some issues. My current design consists of a 555 timer configured in astable operation generating a 50% duty 150Hz square wave which is driving the trigger on another 555 timer configured for for monostable operation. I understand that I can vary the duty this way using a pot. Ok, onto my constraints...I am required to use 3 potentiometers; 1 to set the lower duty cycle limit, 1 to set the upper duty cycle limit, and 1 to vary the duty between the 2 limits. I know i could easily accomplish this using a micro, but I am trying to have everything in hardware. No code.Any suggestions?Thanks

author: duak
author_rank: Super Contributor
timestamp: October 24, 2019, 10:32:23 pm
content: I would start with a triangle wave of the desired frequency. A comparator would have one input driven by the tri-wave and the other from the wiper of pot RV1. One end of RV1 would be driven by a buffered variable voltage with a maximum voltage corresponding to the positive peak voltage of the tri-wave set by RV2. Likewise the other end of RV1 would be driven by a buffered variable voltage corresponding to the negative peak voltage of the tri-wave and set by RV3.If this isn't clear, I can try to sketch it out but it'll take some time.

author: chinook_eng
author_rank: Newbie
timestamp: October 24, 2019, 10:57:36 pm
content: Ok, that sounds reasonable. Itd be like adding hysteresis to a comparator only the upper and lower bounds and reference would all be independently varied. Does that sound about right?

author: chinook_eng
author_rank: Newbie
timestamp: October 24, 2019, 11:20:07 pm
content: Works like a beaut. Thanks for the help duak!
constant-gm bias circuit - Page 1
Forum section: electronics / projects

author: promach
author_rank: Frequent Contributor
timestamp: April 25, 2019, 03:26:41 pm
content: Forhttps://designers-guide.org/forum/Attachments/Improvements_in_biasing_and_compensation_of_CMOS_opamp.pdf#page=3, how to derive expression (14) ?

author: David Hess
author_rank: Super Contributor
timestamp: April 25, 2019, 10:38:28 pm
content: They don't they implement constant Gm the same way it is done in bipolar circuits by adjusting the bias current levels? Or is that what they are proposing? It was not clear to me.

author: silverback
author_rank: Contributor
timestamp: April 26, 2019, 12:17:46 pm
content: To obtain constant GM the bias current Id or Ic for transistors should be proportional to absolute temperature, Iptat.

author: David Hess
author_rank: Super Contributor
timestamp: April 26, 2019, 01:53:54 pm
content: Quote from: silverback on April 26, 2019, 12:17:46 pmExactly, and doing exactly that was an early innovation in bipolar circuit design.Why isn't the same thing done in their example? Is there something about CMOS which makes it untenable?Thinking about it now, I never noticed such a thing in published CMOS operational amplifier designs but I assumed like later published bipolar designs, they just left that part out.

author: promach
author_rank: Frequent Contributor
timestamp: May 05, 2019, 08:07:49 am
content: Do you guys know how to come up with theequationfor RDS4C?

author: promach
author_rank: Frequent Contributor
timestamp: May 07, 2019, 12:35:40 am
content: Someone else had derived the answer
Constant power load monitoring - Page 1
Forum section: electronics / projects

author: thephantom1492
author_rank: Contributor
timestamp: July 17, 2021, 10:06:31 pm
content: Hi there,I need to monitor the power of a constant power load (smps based 9W light) over a wide range of voltage (8-16V) to detect a partially failed light.I can not use a microcontroller because of reasons out of my control. I wish I could...Currently, I found the analog multiplier circuit using opamp, but from what I understood it is unstable with varying temperature, so not great...The other mean I found is to cheat and go with an "idealised" linear slope instead of the real current curve for the comparison, which give precision issue...Is there another good way to do it cheaply and reliably with parts available at jlcpcb?My requirement is:- 9W load- 8-16V input, noisy as heck- detect at 80% of 9W- handle 0-60°C- trip time in 10ms- output 12V when in fault
Constant-power output into load with varying impedance - Page 1
Forum section: electronics / projects

author: KaneTW
author_rank: Frequent Contributor
timestamp: October 28, 2019, 05:14:16 am
content: I'm using a DRV8412 to drive a RLC load at resonance (so it appears like a resistive load) with a fundamental of 40-100kHz. Originally when I chose that IC, I expected the maximum load impedance to be around 20-25 Ohm. However, it appears that depending on load conditions, it can vary between 10-50 Ohm.I've considered using a step-up transformer, but that pushes too much current through the IC at low impedance. Switching 1:1/step-up might be reasonable (e.g. using a Coilcraft configurable transformer), but sounds like a headache to get right.Other options I'm thinking of is redesigning with external FETs (thankfully I'm just using an EVM right now). Using resonance to add gain doesn't work due to my bandwidth requirements.Any other ideas?

author: Marco
author_rank: Super Contributor
timestamp: October 28, 2019, 02:02:31 pm
content: Feed the rails for the DRV8412 with a constant frequency constant duty cycle boost converter.

author: KaneTW
author_rank: Frequent Contributor
timestamp: October 28, 2019, 03:47:13 pm
content: I'm already driving it at the highest DC voltage it recommends (50V), which after selective harmonic elimination and filtering drops down to just about 50V/sqrt(2) RMS, and I need a 60W output. It has an absolute maximum rating of 70V, but that's for transients only.I need to measure the load impedance under real life conditions; if it's more constrained than 10-50 this might be more feasible. Otherwise I'm thinking GaNFET (due to low RDSon and switching losses) at 80V nominal should work and improve efficiency a bit more.Loses the low-effort benefit of the DRV84x2, though.I can already adjust the output RMS by changing the modulation, so a down-regulating the rails voltage won't help. A 1:1.5 step-up might just be good enough if I can accept a slightly reduced full-power range. Efficiency drops to about 92% simulated though (down from 96%) due to the high current through the switches.
Constant Voltage Output  - Page 1
Forum section: electronics / projects

author: jbushnel
author_rank: Contributor
timestamp: January 15, 2015, 01:57:08 am
content: Hello,I have an analog signal coming from a microphone and I was wondering if there is something out there that will output the same signal but only with a defined and constant voltage? I wanted something that will bring my signal to 2V RMS (for example) even if my signal is 1V or 3V RMS. I know an op amp can increase the voltage but the increase will vary depending on the input signal... I just need something constant! Please help!Thanks!

author: digsys
author_rank: Unknown
timestamp: January 15, 2015, 02:24:06 am
content: Look up AGC amp circuits. They can both boost and limit an output signal, depending on how you configure them.

author: jbushnel
author_rank: Contributor
timestamp: January 15, 2015, 02:31:31 am
content: Alright, do you know of any specific IC's or do they not come like that?

author: digsys
author_rank: Unknown
timestamp: January 15, 2015, 03:24:36 am
content: Quote from: jbushnelYou could make your own, many Linear op-amp datasheets have suggested circuits, but it is not a simple circuit.The ICs that I (we) used in the past are probably long obsolete. A quick google of "AGC opamp" found CLC520 (and all in one IC).I'm sure there are many more out there. I'm not saying this one will suit you, but it's a good starting point to find exactly what you want.

author: qno
author_rank: Frequent Contributor
timestamp: January 15, 2015, 07:40:39 am
content: google for audio compressor circuits or units.
construction of a spark chamber,  detection of particles of cosmic radiation? - Page 1
Forum section: electronics / projects

author: Physikfan
author_rank: Regular Contributor
timestamp: October 28, 2017, 07:02:32 pm
content: To all high-voltage friendsPlease, has anyone in this forum made the construction of a spark chamber, for the detection of particles of cosmic radiation?e.g.https://sciencedemonstrations.fas.harvard.edu/presentations/cosmic-ray-spark-chamberRegardsPhysikfan

author: cdev
author_rank: Super Contributor
timestamp: October 28, 2017, 07:49:12 pm
content: There are some circuits onhttp://techlib.com/
Contact closure count on phone app via bluetooth? - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: May 18, 2023, 01:39:39 am
content: Rather than reinventing the wheel, does anyone know if the following might already be available? I want a cumulative (and maybe resettable) count of how many contact closures have occurred in a piece of equipment and that can be read via a phone or tablet app. Contact closures no quicker than maybe once every ten seconds.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: May 18, 2023, 01:52:41 am
content: You need to make a Bluetooth LE peripheral, with a service exposing the count attribute. IOS and Android can easily connect and read out the count. Can also receive notification, is the device has an event. A suitable MCU ishttps://www.adafruit.com/product/4481The bottom line you’ll need to write code.
Contact heart rate measurement - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: July 27, 2020, 10:06:24 am
content: Hi,I want to know how can I measure heart rate using metal contacts, something like in treadmills. any Ideas? or chip we have for them? I want to use it for a fitness app.Thanks

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 27, 2020, 01:27:50 pm
content: That's called ECG/EKG, basically you need an amplifier with a low noise floor and good common mode rejection.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 27, 2020, 01:59:55 pm
content: You can take a look at the AD8232 to begin with:https://www.analog.com/en/products/ad8232.html(and the related docs)

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: July 28, 2020, 08:26:08 am
content: Thanks, for the info, if we have a good app note to understand the concept or a cheap way of doing it from Chinese ppl, it would be very nice
Contactless motor drive - Page 1
Forum section: electronics / projects

author: cio74
author_rank: Regular Contributor
timestamp: December 12, 2011, 09:04:59 pm
content: Hello,Does anyone have any documentation about a contacless motor drive, not sure about terminology. The idea is to have the electromagnetical field generated in a separate piece and the rotor in other. Therefore, one piece can stay in a box while the other outside. Inside the box there are no electrical wires.Here isa commercial example of such product, however it does not fit my needs and I'd like to build my own.Thanks.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: December 12, 2011, 10:13:53 pm
content: That looks similar to magnetic lab stirrers. The motor has a magnet attached to the shaft and spins whatever needs to be spun via a magnet attached to that. Google "magnetic stirrer diagram" and you'll see various configurations. There are other ways to accomplish this, but the magnet is easiest.

author: Zero999
author_rank: Super Contributor
timestamp: December 12, 2011, 11:05:42 pm
content: You've not stated any requirements so you won't get much help.An aquarium pump typically uses a synchronous motor with a permanent magnet rotor. The stator is is sealed and potted in resin so and the magnet is built-into the impeller which forms the rotor.http://en.wikipedia.org/wiki/Synchronous_motor

author: mags
author_rank: Newbie
timestamp: December 20, 2011, 07:45:34 pm
content: Many brushless motors have this kind of topology, with fixed coils on the outside and a rotating permanent magnet.Seal-less pumps add a waterproof membrane between the two.So a brushless motor drive chip might be useful to you. I've never used one myself, but believe that it will help with things like commutation, where it can sense back-emfs in the coils and use them to automatically compute the angular position, and hence commutate the device (fire each coil at the correct time).Otherwise you'll need an additional commutation system (e.g. optical)

author: IanB
author_rank: Super Contributor
timestamp: December 20, 2011, 08:58:48 pm
content: Quote from: cio74 on December 12, 2011, 09:04:59 pmThe terminology is "induction motor". The world is full of them, ranging from tiny fan and disk drive motors in PCs, through drum motors in tumble driers, up to really huge industrial motors.All induction motors require some kind of AC to drive them, either from the mains, or electronically generated and controlled.The motors are most efficient when the gap between the rotor and stator is tiny as this provides the best magnetic coupling. However, with a bigger gap some kind of hermetic seal can be provided that completely isolates the rotor environment from the stator environment, for example when pumping corrosive or hazardous fluids.As mentioned above, laboratory stirrers and aquarium pumps both work on this principle.
contactless payment ring and a tutorial on NFC antenna design - Page 1
Forum section: electronics / projects

author: ultratechie
author_rank: Newbie
timestamp: September 07, 2015, 04:49:42 pm
content: Hi,I have a done a video about a contactless payment (NFC) ring that I have made. The video talks about NFC antenna coil design and how I used the concepts to make the wearable ring.Here is a link to the video:I am a hobbyist and I have started to make some videos about the projects I do. I would like to receive your feedback, especially on the quality of the video and the technical content.Hope you like it.

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 07, 2015, 06:45:04 pm
content: Well doneI have basic knowledge about how NFC works but I liked to see the data on the scope and your '3D' coil.Looking at the data for the 2.2uH coil and the chip I guess you could have just soldered a 27p cap on the coil connections and be done, but for others the tuning demonstration on the SA can be an eye opener.Subscribed!
Contactless Water Level Sensors  - Page 1
Forum section: electronics / projects

author: picandmix
author_rank: Frequent Contributor
timestamp: December 11, 2018, 02:37:23 pm
content: Hi,Does anyone have practical experience of these water level sensors ?Looking at aquarium tank level use, but cannot find any real info on how accurate they are and what the high to low differential is.Have used simple Float switches in the past and they can be surprisingly accurate to a couple of mm, but rather bulky and unsightly in a small tank.Also just testing out an optical senor, but having one of these contactless ones outside the tank would be a much better option if they work ok ?

author: ranthalion
author_rank: Contributor
timestamp: January 21, 2019, 03:03:58 am
content: I've been using a handful of them for various reef aquarium purposes. The work well for me so far. I'm using a one to automate water transfer from RODI to mixing reservior. It's been working well for me sensing through a 55 gallon plastic drum. I also have one on my 30 gallon top off reservoir to notify when the water level is getting low and needs to be refilled. I haven't used it to control the actual top off yet since I have a set of reduntant float valves and a pump handling that for the last several years.https://www.reef2reef.com/threads/water-level-based-relay-controller.487954/#post-5294119has details on my small water level project.

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: January 21, 2019, 08:09:01 am
content: Mmmm I'm interested! Using my DIY float switches (from fleabay) for Airconditioner condensate pump, all OEM sensors kept failing and they cost a lot. I thus made a dual float switch that I connected self holding relay when floats are up, so it stops cycling the pump too much and gives the system hysteresis. Works a treat...except I need a separate or 3rd sensor for Flood. In case the pump fails. Pump is great its just the OEM sensors, Sauermann.I cannot fit another float in as I'm using 50mm PVC pipe as the reservoir. I mean I could if I re-did it all, put the existing floats on the bottom, swap over connections and floats, install another small float in the top, might squeeze. I'm constrained for room as the reservoir fits between walls. So if I can sneak in another small sensor to existing...winning!

author: picandmix
author_rank: Frequent Contributor
timestamp: January 21, 2019, 09:24:14 am
content: Thanks, did order one, but still waiting for it a month later !Been using the optical sensor instead and its giving very accurate level , close to 1mm
contactor buzz after brownout/sag? but not with reset - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: September 03, 2019, 12:49:17 am
content: I have a contactor that is powered by a 12V transformer inside of a distribution box.When I get a brownout, the thing turns off (expected) but then it turns on and it starts humming, until I hit the switch manually to turn it off and then turn it back on.Its literary a filter, transformer (12V) -> contactor.Why does it buzz after it auto triggers but stops buzzing when I switch it on? It makes a thud and everything when it turns itself on after a sag. I can't imagine what is different between the two turn on modes, I even took it apart before and checked the springyness of it (well not with a relay/contactor tester but still it felt decent). How is it loading the transformer to buzz? It's actually REALLY obnoxious. It has that evil street electricity noise. Its not loaded by anything external (test equipment which is all turned off with mechanical switches).its been very consistent so long I reset it manually, as annoying as it is.

author: duak
author_rank: Super Contributor
timestamp: September 04, 2019, 05:33:39 am
content: In general, a contactor with an AC coil draws a very high current until it pulls in - it's far higher than the pulled in current. Does the transformer have enough current to do this? A contactor that doesn't pull in will usually overheat and melt something and all it can take is a brownout. Other things to check are line frequency and temperature. Also, is the contactor oriented correctly - some are sensitive to being mounted upside down.

author: coppercone2
author_rank: Super Contributor
timestamp: September 04, 2019, 10:04:17 pm
content: its upside down, I did not think this mattered

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 05, 2019, 12:17:32 am
content: Try adding a capacitor in parallel with the contactor to counter the inductive reactance and reduce the load on the transformer.

author: coppercone2
author_rank: Super Contributor
timestamp: September 05, 2019, 12:22:36 am
content: Quote from: NiHaoMike on September 05, 2019, 12:17:32 amwhy would this help on a brownout reset ? 99% of the time its fine.
Contactor - help interpreting electical contactor data sheet. - Page 1
Forum section: electronics / projects

author: DTJ
author_rank: Super Contributor
timestamp: September 24, 2022, 09:55:19 am
content: Hey guys are there any heavier electrical types here that can assist me to interpret a contactor data sheet?I'm repairing my 30 year old MIG welder - the contactor that powers up the weld current transformer has failed. The pull in coil (220V) has failed open circuit.The contactor is no longer available.It has two NO contacts that switch the active and neutral to the transformer primary. It also has a couple of NC contacts that drop a 20 ohm power resistor across the output capacitor bank when the contactor drops out to reduce the welding wire voltage to zero.I've found this contactor that looks like it may do the job.Am I correct in thinking this contactor has 3 separate NO contact pairs plus 1 separate NC contact pair?Attached are pic of the contactor + data sheet.Thanks

author: H.O
author_rank: Frequent Contributor
timestamp: September 24, 2022, 11:27:51 am
content: That's correct.Three main N/O contacts and one auxillary N/C contact

author: DTJ
author_rank: Super Contributor
timestamp: September 24, 2022, 12:32:21 pm
content: Quote from: H.O on September 24, 2022, 11:27:51 amExcellent. Thanks HO now I've got the confidence to order the unit.Cheers!
Contents of Serial EEPROM - Page 1
Forum section: electronics / projects

author: MrSquirrel
author_rank: Contributor
timestamp: January 11, 2018, 09:23:26 pm
content: Hi folks,I'm digging around in a piece of kit and wondering if anyone can cast their eyes over this dump from a Serial EEPROM.I can't make any obvious sense of it, it should contain some FRU data like Ethernet MAC addresses, calibration etc, so am guessing it is obfuscated in some way.Just wondering if any of you guys can see anything obvious?In this situation i would normally sniff the I2C bus and watch which locations are being read by the host system to give me an idea on structure of the ROM data as a starting point. Only problem is it appears my Intronix Logicport can't handle the speed of the clock....Update, it's okay i worked it out.Thanks,
Continuously variable power factor capacitor idea - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: January 21, 2025, 01:59:16 am
content: Sometimes you want to find the optimum size power factor correction capacitor to put across a particular load and you end up trying various discreet values until a suitable value is found. Or maybe you need a set of big variable capacitors to excite a stand alone induction generator. What about the following approach? Get a variac and put a suitable (but relatively small) capacitor permanently across the mains input side so the variac draws essentially zero reactive power. Then connect a relatively large power factor cap across the output of the variac. Connect the variac input to whatever needs an adjustable capacitor.According to my way of thinking, as the variac is adjusted up and down, the voltage on the output side capacitor varies accordingly, and so it draws an adjustable amount of reactive power. This adjustable amount of reactive power appears at the variac input and so appears as a continuously variable capacitor.I might have posted this idea some time ago and forgotten about it.

author: inse
author_rank: Super Contributor
timestamp: January 21, 2025, 05:10:00 am
content: All theory aside, wouldn’t a DIY capacitor decade box be both more handy and sufficient as well?

author: johansen
author_rank: Super Contributor
timestamp: January 21, 2025, 05:50:56 am
content: It works, very few people understand that the change in effective capacitance follows the square of the voltage transformation by the variac.Its very useful to find the optimal motor run capacitor to maximize efficiency.

author: coppercone2
author_rank: Super Contributor
timestamp: January 21, 2025, 08:17:33 am
content: Hmm and you can put a DPDT switch on a variac to disconnect the mains and connect it to banana jacks so you can plug it in the lab nicelyor a IEC to banana adapter (for the receptacle, not the cable side)or outlet to female banana connectorTheoretically safe if there is no suicide cables laying around
Control 64 rgb leds for a pov display - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: August 22, 2013, 01:02:04 pm
content: Hi,i have to build a pov display with two blades with 64 rgb leds on each of them (128 leds total).I was thinking of using the TLC5947 to control the leds, but it is a little expensive, can someone reccomend a cheap alternative?I need at least 8 bit pwm and current control.Thanks for the help.

author: timbos
author_rank: Contributor
timestamp: August 23, 2013, 07:08:45 am
content: You can get addressable RGB strips with 60led/m which are controllable with a micro. They use a chip that I think is a WS2801, which talks using a 1-wire serial protocol, although there's also an I2C version IIRC.Don't know what your pov application is, but I've used one of these strips for a simple pov and light painting rig.

author: David_AVD
author_rank: Super Contributor
timestamp: August 23, 2013, 07:34:06 am
content: The 2801 chip is data+clock and very easy to drive. The 2811 chip is Manchester and very fussy timing wise. You can get 5050 RGB LEDs with inbuilt 2811 chip now too.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 23, 2013, 09:21:02 am
content: Quote from: exapod on August 22, 2013, 01:02:04 pmThink about what PWM frequency you might need for POV.....
Control a 4 wire bldc computer fan. - Page 1
Forum section: electronics / projects

author: cybertronicify
author_rank: Regular Contributor
timestamp: August 08, 2015, 02:49:26 am
content: Hello everyone!I would like to control this, nmb-mat bg0903-b049-p0s, bldc computer fan with the built in CONTROL wire. How can I do that without a bulky circuit? I am trying to make a self contained fan that i can adjust the speed of the fan. It uses PWM signals, can i use a 555 timer for this? It is also based on 12v so if i operate the 555 timer at 12v, can it give out a 12v signal? I would prefer as little components as possible.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 08, 2015, 03:01:00 am
content: Standard is a 5V or 3.3V PWM signal at 25kHz. Beware that some fans like the ones used in some Daikin indoor units use something else - one of those needs inverted PWM and works erratically at 25kHz.

author: dom0
author_rank: Super Contributor
timestamp: August 08, 2015, 07:14:43 pm
content: This specification will answer all your questions:http://www.formfactors.org/developer%5Cspecs%5Crev1_2_public.pdf(mainly page 9)

author: Spikee
author_rank: Frequent Contributor
timestamp: August 08, 2015, 08:54:49 pm
content: Maxim have these devices that work via I2C that can control these fans with no issue.I have used them before and they are great. I do not have a part number for you but this should not be hard to google.

author: cybertronicify
author_rank: Regular Contributor
timestamp: August 09, 2015, 05:01:06 am
content: Thanks for the replies! I hook this up to a mosfet that either shorts control to ground or doesn't short to ground. Used an arduino to do the switching, but this fan responds just tooooo slowly. It does this extremely slow ramp up, but the speed drops like a brick wall when i slow it down. I guess i'm back to voltage control. LM2596 should do.
Control all features of your car by voice commands - Page 1
Forum section: electronics / projects

author: TechQuirks
author_rank: Newbie
timestamp: March 19, 2022, 11:32:50 am
content: I've been working on it for a while and eventually it's done. I integrated an Artificial Intelligence system in my Toyota86 and made a short movie about the process.Well, kind of, artificial intelligence, but more like a tweaked smart speaker with a voice recognition module and Arduino hooked up to its side. Check it out please:

author: zakariyoung
author_rank: Newbie
timestamp: April 06, 2022, 02:52:58 pm
content: Watched your video! Very interestingly done! Didn't pay attention to thehb3 headlight, because smart headlights are not only good light, many modes on the lens drum, but also the lens turns left and right when turning. When you turn on the light, the smart headlights do a nod up and down, the autocorrector is responsible for this, and left and right.
Control Amperage Using Components On A BreadBoard? - Page 1
Forum section: electronics / projects

author: roonymax
author_rank: Newbie
timestamp: June 14, 2017, 04:21:50 pm
content: I'm trying to build a basic powersupply using a breadboard, I know how to control the voltage using resistors. But i'm stumped how to control the amperes.Basically what components do i need to control the amperage on a breadboard? Capacitors etc.,?Thanks.

author: rdl
author_rank: Super Contributor
timestamp: June 14, 2017, 04:46:53 pm
content: You can try watching Dave's video #221. It should give you a start.

author: Probb
author_rank: Contributor
timestamp: June 15, 2017, 04:24:31 am
content: Depends on what exactly you're trying to do. Do you want to have a single current limit that the power supply can provide, or do you want to be able to vary current limitations? OR do you want the supply to act more as an ideal current source?If you're just looking to power a simple circuit or two on your breadboard, then you probably only need to design for a single current limit, and that really just comes down to the ratings of the components you're using (and some protection circuitry if you want to get a little fancy)Also, are you working with a linear power supply set-up, or switch-mode?Sorry if this is too many questions hahah. Based on your question, I'm going to guess you're likely working with some kind of linear supply set-up; maybe even just a voltage divider...?
Control ISD17120PY using SPI - Page 1
Forum section: electronics / projects

author: backd00r
author_rank: Contributor
timestamp: May 15, 2015, 02:16:09 pm
content: Hi I would like to know if there is a way to control the ISD17120PY recording chip using the SPI with a PIC. In order to use the pic as input for the ISD operations (record,play,forward,erase..). Also how would this work? I am totally new to SPI protocols.Thanks
Control loop of a buck-boost converter - Page 1
Forum section: electronics / projects

author: Teun
author_rank: Regular Contributor
timestamp: July 24, 2025, 09:36:37 am
content: Hi,I'm trying to calculate the exact values needed for a control loop on a BB-converter. The datasheet for the controller only gives me this information:Am I right to assume this would be a type 2 or 3 OTA control loop as described in this document:https://www.ti.com/lit/an/slva662/slva662.pdf

author: jwet
author_rank: Frequent Contributor
timestamp: July 24, 2025, 03:21:43 pm
content: I simply googled the data sheet and found a 15 page data sheet that covers calculating all the external components in detail with formulas, etc. Maybe you got the short from datasheet? I can't attach the DS here but the footer on page 1 says:DS-PL5501-Rev. 1.0www.powlicon.compage 1 of 15Try googling it.The amplifier appears to be an OTA type with 400 uS of Gm. Be careful though, one of the difficulties of applying "academic analysis" as in the TI paper to modern switchers is that the control is generally not completely linear or text book and has extra little tweaks for corner cases to enhance operation. The vendors don't tell you everything that goes on especially in special cases. As an FAE for Maxim, it was difficult to talk to old school switching power supply designers that came up with old Unitrode parts or discrete designs. The original Unitrode parts were very simple and transparent. The modern switching supplies from Maxim, LTC etc, were really a reaction to this kind of complexity. They enabled a normal "digitial guy" to put a small point of load switcher together by just following the DS guidance. The kind of knowledge in that TI App Notes is still necessary but is now done by the chip companies and understood by the designers, product definers and occasionally senior FAE's.EDIT- The data sheet doesn't give any guidance on the calcs for these devices, ,my mistake, they only have chosen values in the final schematic. 10K and 10nF sounds pretty swaggy- this would be a corner at 1600 Hz, seems low but a place to start. Sorry for the confusion- I guess you're on your own. The PL5501 looks like a copy of a National TI LM5176 roughly, it has a different Gm but the data sheet does go through the calcs. LM51770 is related more modern device.

author: Teun
author_rank: Regular Contributor
timestamp: July 25, 2025, 07:16:21 am
content: well thanks anyway. I will have a look at the ti datasheets.
Play With My XYZ Gantry (configured as a plotter) on Twitch.tv (Src docs inside) - Page 1
Forum section: electronics / projects

author: cteffects
author_rank: Newbie
timestamp: June 07, 2018, 05:49:27 pm
content: Just showing off my CNC Gantry I made.I finished the physical part about 6 months ago, and whipped up some rudimentary firmware to get the thing moving back in January (I think?). I put it on Twitch.tv, and advertised through /r/electronics and people made a few interesting drawings:https://imgur.com/a/nshuy#CJJYYamhttps://clips.twitch.tv/BumblingSwissMangoMVGameNow, I've completely rewritten the firmware for robustness (almost there), performance (much better than my alpha-level crap), and more real-time control. Only the basic commands are implemented so far (linear move, lerp-rate move, timed delay, halt, unhalt). The command set is a binary protocol generated through a python library which includes a small vector math and polygon manipulation companion lib for geometry operations.The Twitch stream can be found here, please try to break my stuff and find bugs!:EDIT: Someone already figured out how to crash my print server, so I get to figure out what went wrong when I get home from work. That's a big help! Thanks for finding that flaw in my code.https://www.twitch.tv/mistermicstwitchaccountGoing to try to run it through Sunday, June 10th, periodically changing out the paper and monkey-patching my code with bug fixes based on stuff people may find.The Github is here:https://github.com/cteffects?tab=repositoriesI made everything here, so feel free to use all or parts of my code, models, and schematics for your own use, with or without attribution. I don't care.And here are the rest of the resources (sorry for the lack of documentation, I've included a lot of pictures though)...Gerbers:https://drive.google.com/drive/folders/1gRdetmCG4Y085XrXNdbWleRHjThaZ--3?usp=sharingKiCad Schematic:https://drive.google.com/drive/folders/196OUVJxWbJbL6YWqwgLoZoqQseEsVg42?usp=sharingOn-Shape CAD Model:https://cad.onshape.com/documents/6ef4c249d853bee48a963e71/w/2cd24da5185616801a245284/e/b2289e11752bc6ec7b2aa0f6Reasonably Accurate BOM:https://docs.google.com/spreadsheets/d/1j1f-tX5ejILHTC0Dav7CV_67HHb2XNh98clio1pmJ1E/edit?usp=sharingPhotos Photos Photos:https://imgur.com/a/ulout
Control of RFID reader's field  - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: June 20, 2024, 10:11:03 pm
content: Hi,I need to make a A4-sized PCB with an array/grid of RFID coils to detect on top of which coil a very tiny tag is placed. The tag is always positioned precisely on top of a coil (or at least 90% of it is inside the coil circle/square). More than one tag can be placed on the PCB at the same time but never on a position/coil where there is already another tag. And I need to fit as many coils as possible in the A4 area. The distance between the tag and the coil is always between 1 to 3mm at most.Could anybody provide any tips on the following:1) what is the best way to ensure a short/limited/confined read area and range (detune the antenna, small antenna, low number of turns, other)? Maybe there are some small range-limited tags?2) what frequency is best to provide strong field within the defined antenna area but that it falls off rapidly just outside the antenna area? Would it be a low freq 125KHz or the high frequency 13MHz?3) any tips how to make the field more directional (along the coil axis)? i.e. more like a tube above the coil instead of a toroidal-like shape (that expands more outside of the coil too)?Thank you

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 20, 2024, 10:26:38 pm
content: For that scale 125kHz is probably better - more well-defined range ( of the order of a sphere the diameter of the coil) and easier hardware - you can use a simple multiplexer. on one or more readers, depending how fast you need the result.At this sort of range you don't need to worry too much about antenna tuning. You can control range pretty predictably by adjusting the excitation power.To minimise interaction between could you probably want the coil diameter to be similar to the spacing between the edges of the coilsDownsides of 125k vs. 13.56MHz are :You probably need more turns on the coil, - probably still doable as PCB but you might need 4 layersSlower read time - from memory maybe 50-100mS depending on tag type. There are tricks you can use to reduce peak latency, like having a read algorithm that can start anywhere in the readback cycle to avoid having to wait for the start.Larger minimum tag size

author: Benta
author_rank: Super Contributor
timestamp: June 20, 2024, 10:30:31 pm
content: Chess board, eh?Definitely 125 kHz. There's basically zero RF there, it's pure electromagnetics. Don't even think "antenna".Inductive coupling, field shaping, all managable.
control pin state at power up - Page 1
Forum section: electronics / projects

author: ToBeFrank
author_rank: Regular Contributor
timestamp: August 03, 2011, 07:29:46 am
content: I'm using an Arm Cortex M0 micro. The reset state of all gpio pins is input with pull-up enabled. I need one pin to be low on power up because it is connected to a bus where high is considered to be active on the bus. What can I do to make sure this pin is low at reset? I tried various values of pulldowns (100k down to .5k) and none of them worked.

author: Bored@Work
author_rank: Super Contributor
timestamp: August 03, 2011, 08:11:17 am
content: Measure.If a 500 Ohm resistor can't pull down the bus it could be- that you have connected another pin to the bus, i.e. you are messing with the wrong pin- that something else is pulling the bus upTherefore measure what is really going on on the bus, e.g. how much current is going through your pull-down resistor.And if you are willing to risk some magic smoke, use a stiff wire to pull the pin to ground. The component that starts to get hot or releases the magic smoke is likely the one trying to pull the bus up.

author: A Hellene
author_rank: Frequent Contributor
timestamp: August 03, 2011, 11:05:57 am
content: Well, how about using a Reset Supervisor chip (in a TO3/SOT23/etc. 3-pin package), to be sure?-George

author: Bored@Work
author_rank: Super Contributor
timestamp: August 03, 2011, 11:18:51 am
content: It doesn't make sense to throw more hardware onto the problem if you don't know what the problem is. So let me repeat: Measure.

author: A Hellene
author_rank: Frequent Contributor
timestamp: August 03, 2011, 11:27:27 am
content: Quote from: ToBeFrank on August 03, 2011, 07:29:46 amOops... I thought I read that the pull-down range resistors were 100K ..5K...Sorry for that. If a 500 Ohm resistor failed to pull the line down, YES, measure and investigate what the strong pull-up source is.-George

author: ToBeFrank
author_rank: Regular Contributor
timestamp: August 03, 2011, 05:09:04 pm
content: Thanks guys. I thought I must be doing something wrong when the pull downs didn't work. I'll measure the current tonight. Fortunately, I don't have to worry about the magic smoke because the bus is guaranteed by it's specification to handle short to ground.
Control Protocols over IP For machinery - Page 1
Forum section: electronics / projects

author: mrpackethead
author_rank: Super Contributor
timestamp: May 29, 2016, 09:47:10 am
content: What protocols for controlling factory machinery are available for running over IP networks?I have a PC that needs to send command to number of devices ( motor drives, solenoids etc ) and also get a number of sensor data amounts back as well.

author: Psi
author_rank: Super Contributor
timestamp: May 29, 2016, 09:49:47 am
content: Modbus over TCP is one i know of (although i'm not suggesting you use it)Maybe look through this list herehttps://en.wikipedia.org/wiki/List_of_automation_protocols

author: Pjotr
author_rank: Frequent Contributor
timestamp: May 29, 2016, 10:28:46 am
content: If latency is of concern, i.e. control loops, EtherCAT:https://en.wikipedia.org/wiki/EtherCAT

author: lincoln
author_rank: Regular Contributor
timestamp: June 01, 2016, 10:46:25 pm
content: Not a control protocol but PTP/ IEEE 1588 is also use to help synchronize equipment.https://en.wikipedia.org/wiki/Precision_Time_Protocol

author: hendorog
author_rank: Super Contributor
timestamp: June 08, 2016, 06:28:04 am
content: I've been at an EtherCat roadshow today, pretty impressive latency compared to the competition.It is compatible with Ethernet - an ordinary PC can act as a master without extra cards etc.
Control system to sync/phase lock VCOs (hysteretic converter sync) - Page 1
Forum section: electronics / projects

author: uer166
author_rank: Super Contributor
timestamp: August 10, 2022, 05:39:48 am
content: The idea is a little vague, but say you have a few voltage controlled oscillators (in this use case hysteretic converters) that have some inaccuracies and non-linearity, as well as not necessarily being time invariant. So a DAC voltage goes in, a digital output of varying frequency goes out, and you're trying to maintain a certain phase relationship between them, which also means they're synced in frequency.The measurements available here are just the digital outputs of the "VCOs" using timer capture peripherals or similar. How would I devise a control system to lock frequency and control? I can't quite figure out a small signal transfer function for something like this easily, and also not sure how to even get a control variable? The frequencies involved are 100-300kHz at most.The idea is obviously to interleave hysteretic current mode converters, which normally is not done.
control systems - Page 1
Forum section: electronics / projects

author: whatty
author_rank: Contributor
timestamp: May 17, 2023, 05:50:06 pm
content: Hi there now i had studies the basics in control system theories now i am interested to learn designing control systems for dc to dc converters so can anyone suggest me a book which explains with examples in dc to dc converters or any power electronic controller how feedback loop implemented or how the system is designed it should have worked examples too.Thank you in advance..

author: brokenslinky
author_rank: Newbie
timestamp: May 18, 2023, 02:32:58 pm
content: TI, Analog and the other IC manufacturers tend to have decent papers associated with each product. Maybe do a search? I came up with this paper rather quickly:https://www.ti.com/download/trng/docs/seminar/Topic%206%20-%20DC-DC%20Power%20Conversion%20and%20System%20Design%20Considerations%20for%20Battery%20Operated%20System.pdf

author: Someone
author_rank: Super Contributor
timestamp: May 18, 2023, 11:24:14 pm
content: This person claims to have the answers:https://www.ridleyengineering.com/education/books/power-supply-design,-vol-1.html

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 19, 2023, 06:07:20 pm
content: Have a look about the pdf below.It's 63 pages about using the TL431 and designing a control system around it, inclusive handing of an optocoupler in the loop.
Control Voltage Current Draw for OCXO? - Page 1
Forum section: electronics / projects

author: t1d
author_rank: Super Contributor
timestamp: January 22, 2023, 10:37:50 pm
content: I have purchased an OCXO. The data sheet states that the unit operates on 5V and draws a maximum of 600mA, upon start up. The voltage for the frequency adjustment is +/-2V. However, the current draw for the frequency adjustment voltage is not stated in the data sheet. Should I assume this draw to be the same as the working voltage, as much as 600mA on start up? Thank you for your help.

author: TimFox
author_rank: Super Contributor
timestamp: January 22, 2023, 10:45:44 pm
content: Line 21: the input impedance at the voltage control is specified as 100 k, wherefore the current drain should be around 20 uA at 2.0 V.

author: t1d
author_rank: Super Contributor
timestamp: January 22, 2023, 10:53:35 pm
content: Quote from: TimFox on January 22, 2023, 10:45:44 pmExcellent; thanks Tim. I think that I have also been misinterpreting the control voltage as +/-2V. At a ambient temperature of 25C, the needed control voltage is +2V = ~0 adjustment. The control voltage can go up to 4, or down to 0 volts. This means that I will not need a negative voltage supply. That makes the design more simple.
controlled ethernet switch - Page 1
Forum section: electronics / projects

author: oto313
author_rank: Newbie
timestamp: September 21, 2018, 08:57:49 am
content: Hi,I need to automatically disconnect the RJ45 cable from a computer. Now I have to manually disconnect the cable from RJ45 socket. I would like to create a device which has one ethernet input, one controlled ethernet output and power supply with a control pin. Using the control pin, I should be able to disconnect output from input. Is there any simple way to do that without using multiple relays? Is there any ic which can do that?Parameters:I/O ethernet speed: 100Mbit or better 1000MbitPower supply voltage: 5VThanks for help

author: Rerouter
author_rank: Super Contributor
timestamp: September 21, 2018, 09:25:47 am
content: just buy a literal ethernet switch and switch its power?https://static.tp-link.com/res/down/doc/TL-SF1005D_12.0.pdf

author: oto313
author_rank: Newbie
timestamp: September 21, 2018, 02:17:06 pm
content: I would like to have one standalone PCB, where are all components. Moreover, I am limited with power supply current. So I would like to use some differential switch circuit using transistors if there are no ICs which can do it. Is there any circuit for the differential switch (maybe similar to a differential amplifier)?

author: ajb
author_rank: Super Contributor
timestamp: September 21, 2018, 02:39:34 pm
content: There are some ICs out there that are designed for this sort of thing, here are some examples from a brief google search:https://www.diodes.com/products/connectivity-and-timing/switches-mux/protocol-switches/lan-signal-switch/But you could also just use some low signal relays. You'll need four DPDT for gigabit since it's four pairs. People tend to freak out about signal integrity, but the reality is that using relays is standard in Ethernet fail-to-wire applications, and anyway a set of relays aren't likely to be any worse than any of the really shoddy patch panels that Ethernet regularly copes with in the real world. You can use latching relays if you want to limit your average power consumption with a small MCU to drive the coils.

author: xani
author_rank: Frequent Contributor
timestamp: September 21, 2018, 03:52:22 pm
content: Just buy a cheap managed switch and switch ports using that

author: Raj
author_rank: Frequent Contributor
timestamp: September 22, 2018, 04:37:21 pm
content: Why? Why not disable modem from device manager?

author: Jeroen3
author_rank: Super Contributor
timestamp: September 23, 2018, 02:25:37 pm
content: Does it really need a physical disconnect, or is a logically disabled port enough?

author: TomS_
author_rank: Frequent Contributor
timestamp: September 23, 2018, 09:54:38 pm
content: Quote from: xani on September 21, 2018, 03:52:22 pmThis.