hybridfree/eevblog-posts huggingface dataset:
light bulb control using raspberry pi - Page 1
Forum section: electronics / beginners

author: stoica adrian
author_rank: Contributor
timestamp: June 03, 2016, 08:01:02 pm
content: Hi,Me and a friend of mine we want to make this project. We want to control the luminosity of our bulb lightroom using a phone. We want to make this using a raspberry pi. I am a full time electronics tehician, he is an full time progamator, so all the programing softuare goes to him.Fore the interface between raspberry pi and bulb i want to use this:http://www.instructables.com/id/safe-and-simple-AC-PWM-Dimmer-for-arduino-Raspberr/But i don't know how to make the interface between phone and raspberry pi.ideas?

author: sokoloff
author_rank: Super Contributor
timestamp: June 03, 2016, 08:57:38 pm
content: I'd use wifi as the easiest common protocol. Give the RPi a wifi adapter (or just use an RPi3 with it built-in), and then either use the phone talking directly talking to the Pi, or have both connecting to a common server. (The latter allows control from anywhere; the former is more appropriate for an in-house only.)

author: netdudeuk
author_rank: Frequent Contributor
timestamp: June 03, 2016, 09:48:59 pm
content: Something like this ?https://pimylifeup.com/raspberry-pi-cayenne/

author: Ian.M
author_rank: Super Contributor
timestamp: June 03, 2016, 10:40:29 pm
content: I've got a very low opinion of any instructable that suggests building mains projects on any type of perfboard without dedicating a whole step to ensuring creepage and clearance distances are adequate. If someone builds this on matrix board that's got plated through holes or a top-side ground plane, it would be pretty dangerous. I would also recommend using a Dremel cutting disk to slot the board directly under the Optocoupler to improve the creepage distance.
light dependant resistor experiment - Page 1
Forum section: electronics / beginners

author: krayvonk
author_rank: Regular Contributor
timestamp: March 16, 2020, 07:13:57 pm
content: Compared to a normal resistor, the light dependant resistor only seemed to heat up a little bit, even at about 40 watts. the normal resistor was super hot in the first second.I was holding it pretty close to my kitchen light, and guess what I just did another one, charged a capacitor then ran a hobby motor for a short burst, so the electricity really was going through it, and it didnt heat up at all!If thats the case, why do ppl even use normal resistors, cause they heat up so bad!!!

author: krayvonk
author_rank: Regular Contributor
timestamp: March 16, 2020, 07:43:46 pm
content: er sorry false alarm...I must have had residual power in the cap, and... I couldn't even run the dc motor the next time round oh well.

author: StillTrying
author_rank: Super Contributor
timestamp: March 16, 2020, 07:49:36 pm
content: Your posts are too troll like, try to make them interestingly sensible instead.

author: gbaddeley
author_rank: Regular Contributor
timestamp: March 17, 2020, 06:37:44 am
content: LDRs don’t generate electricity, and all LDRs I’ve seem would be fried if they dissipated more than 1 Watt or so.

author: krayvonk
author_rank: Regular Contributor
timestamp: March 17, 2020, 09:59:52 am
content: I got to bed, woke up and did it again. And it did actually fill the capacitor! and then I put 12 in parallel then it managed to spin the hobby motor. =)Id say u r right they are about 1 watt each. (so if you want a 100 watt robot you need to tower a 100 to run the motor.)

author: Zero999
author_rank: Super Contributor
timestamp: March 17, 2020, 10:04:15 am
content: Quote from: StillTrying on March 16, 2020, 07:49:36 pmQuote from: gbaddeley on March 17, 2020, 06:37:44 amI think it's likely the original poster has confused the LDR with a photovoltaic cell, rather than trolling. Don't forget, this is the beginners section.
Light detection circuit and LED driver IC - Page 1
Forum section: electronics / beginners

author: shobo
author_rank: Regular Contributor
timestamp: January 27, 2021, 10:49:36 pm
content: Hello!I want to build a small circuit with light detection that will cause a string of UV leds to go on.The plan is to use an 18650 to power everything,with TP charging circuit and a 5v boost converter to get a stable voltage.Can anyone recomend a circuit that can switch a led driver IC on?Can anyone recomend a LED driver IC that needs no external components?there will be a string of 15 UV LEDs (i have not chosen them yet,need some more info)

author: alsetalokin4017
author_rank: Super Contributor
timestamp: January 28, 2021, 06:23:21 pm
content: well a lot depends on specific details but making some default assumptions I'd do this:AP2502 current sink can drive 4 LEDs at 20 mA and has enable pin, IIRC. So use 4 of these, parallel their enable pins, and use a light-dependent resistor aka CdS photocell and a simple opamp comparator circuit for the light detection stage. Again, depending on specific details, you might be able to get away without the opamp comparator and just connect the CdS ldr directly to the Enable pins of the current sinks.https://www.diodes.com/assets/Datasheets/AP2502.pdf

author: doublec4
author_rank: Regular Contributor
timestamp: January 28, 2021, 06:40:58 pm
content: Quote from: alsetalokin4017 on January 28, 2021, 06:23:21 pmI'm also looking at some LED drive solutions right now... I see this device is listed as constant current sink... is this just another name for a linear current LED driver? Are they performing the same function?

author: alsetalokin4017
author_rank: Super Contributor
timestamp: January 28, 2021, 07:13:15 pm
content: I think so. This device goes between the cathode of the LED and the negative rail, and no current-limiting LED resistor is needed (duh.) The Enable pin allows basic on off control at PWM frequencies so it can even be used for dimming, but here we just want on and off I think.
Light diffusers for dot matrix - Page 1
Forum section: electronics / beginners

author: congia
author_rank: Contributor
timestamp: April 25, 2017, 03:05:59 pm
content: Hi, I've got some noob questions. A friend of mine is doing a lighting project for a festival event in Sydney, and here's her funding requestpage (not asking for $, it's not my project either). On the page, it's mentioned that they are using 1mm polyproperline as the light diffuser material for a bunch of dot matrix panels. A stroll around eBay showed the diffuser producing blurred soft edges and the rendered image shows sharp rectangular boxes. Is it actually possible to achieve theend result that's being shown on the top of the page?:https://www.gofundme.com/vividmailboxsydney:https://d2g8igdw686xgo.cloudfront.net/19684710_1492823045.4877.png

author: tablatronix
author_rank: Regular Contributor
timestamp: April 25, 2017, 04:28:47 pm
content: 3m makes diffusion films with various diffusions. Not gonna be cheap.Only other thing I can think of is increasing the distance to the diffuser...Or finding some other film that cheap and has decent internal refraction, or maybe a mutli layer approach, thin opaque white, thicker semi opaque matte film on top.

author: congia
author_rank: Contributor
timestamp: April 25, 2017, 04:39:34 pm
content: Quote from: tablatronix on April 25, 2017, 04:28:47 pmHey thanks for the reply. Are you saying that their proposed cost for the diffuser isn't enough?I'm looking for general info on the topic since it looks pretty interesting. Is there some resources you'd recommend to learn about different types of diffusers and how to apply them to get different results?Thanks.Sent from my iPhone using Tapatalk

author: tablatronix
author_rank: Regular Contributor
timestamp: April 25, 2017, 05:14:44 pm
content: Maybe check with a sign company, see what they can provide to diffuse led backlit signs?For example, here are some of 3m's illumination diffusion films, there are other films for led panels, and edge lit diffusions.http://www.3m.com/3M/en_US/company-us/all-3m-products/?N=5002385+8709314+8709363+8710674+8711017+8718949+8729400+8735263+3294857497&rt=r3Not sure if you can get away with a non specialized plastic film if your diffusion is too close to the leds.

author: tablatronix
author_rank: Regular Contributor
timestamp: April 25, 2017, 05:23:23 pm
content: oops that might be the wrong link, that might just be clear weather films.this says diffusionhttp://www.3m.com/3M/en_US/company-us/all-3m-products/?N=5002385+8709314+8709363+8710674+8711017+8718949+8719034+8729400+3294857497&rt=r3
Lightning Standards - Page 1
Forum section: electronics / beginners

author: darthhideous
author_rank: Newbie
timestamp: January 15, 2019, 01:34:44 am
content: What are the main differences between AS/NZS 1768, IEC 62305 and NFPA 780? If a product is compliant to AS/NZS 1768, would it also be compliant to the other two?
Limit current for Li-Ion battery charging - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: December 12, 2017, 07:16:13 am
content: 1. I have a 11.1V/4.4Ah lithium battery, whose full charge voltage is at 12.6V2. there is separate 12.6V/5A adapter in the instrument where we need to fit the battery.3. Goal is that if mains is not availabel, system switches to battery & if main is present, it both charger battery with 1.5A & supply current to load also.4. Adpater is not itself current limiting, so it will send over current to battery, what is right way to limit current in battery so that it wont take more than 1.5A for charge.

author: David Hess
author_rank: Super Contributor
timestamp: December 12, 2017, 02:45:26 pm
content: Depending on exactly how much higher the charge voltage is than the battery voltage, a low dropout current limiting circuit will be required. This could be combined with the input diode which disconnects the battery from the DC input when power is removed.Protection against over discharging the battery should be included to prevent damage to the battery.
Limit inital current of devices - Page 1
Forum section: electronics / beginners

author: Spike101
author_rank: Contributor
timestamp: January 08, 2014, 10:46:04 am
content: Hello,I am working on a project where we use 4 PC-Engines ALIX boards (x86 boards), which are all powered by an 12V-18Ah battery. Each board draws about 300mA current. When everything is running, the system draws about 1.2A. Until now, I was using a Lead-Acid battery, however I switched to a LiFePo4 battery. With the Lead-Acid battery there was no problem. But with the new LiFePo4-Battery the BMS of the battery does not allow turning on all 4 boards at once. It seems that when switching it on, the boards draw more current, and the BMS of the battery disconnects the battery via a P-Channel FET in order to protect it. According to the manufacturer of the battery, the current draw is limited to 8A, before it switches off.When i connect only 2 boards and a relay-coil to the battery, and the other 2 boards via the contacts of the relay-switch, it works. So it seems, that this small delay introduced by the relay is enough to make it work. But there has to be some better solution than that. I also tried using a series resistor. That does work, but it dissipates too much power, so unfortunately, that's not an option. But sice it works, it seems, that at least the boards don't relly need the high current in order to start, they just take what's available...Is there some better way to limit the maximum current that the system can draw from the battery?thanks in adavance,Sebastian

author: alxnik
author_rank: Regular Contributor
timestamp: January 08, 2014, 01:23:18 pm
content: http://en.wikipedia.org/wiki/Inrush_current_limiter

author: SeanB
author_rank: Super Contributor
timestamp: January 08, 2014, 01:31:12 pm
content: Current sequencer, basically a small board with 4 mosfets on it to switch each board on at 0.1 second intervals. What is happening is that the internal capacitors on the boards are all being charged up at the same time, and this current is too much for the BMS to handle. Otherwise a low Dc resistance inductor in the power line to each board will provide current limiting for the initial pulse. Try 10mH as a starting value, the inductor can be the common one used in car audio as a power supply choke.

author: tszaboo
author_rank: Super Contributor
timestamp: January 08, 2014, 02:48:46 pm
content: Most hot swap controllers have the required functionality to complete this task. Head to TI/AD/Linear/ONsemi for one.

author: Spike101
author_rank: Contributor
timestamp: January 08, 2014, 05:44:36 pm
content: Thanks for all your great suggestions and information.I ordered a few components today, and will try it tomorrow. I'll let you know if it did work.

author: peter.mitchell
author_rank: Super Contributor
timestamp: January 09, 2014, 01:44:09 pm
content: you could also slow down the current sense loop just a little with a cap so that small spikes don't put it over.
Limitations while communicating with LoRa Gateway - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: May 21, 2019, 06:58:50 pm
content: While learning LoRa did not get answer to a questionFor example if I have a Gateway that supports 8 nodes in parallel (node could be SX1276/78 or any other module, or you can recommend some for such task)I have 50 nodes to send data to GatewayWhat will happen if more than 8 nodes sends data to Gateway at the same time,Is there some mechanism that can handle such situation in LoRa devices/protocolMy question is not regarding any project, its only about concept, that's why I'm not mentioning any specific gateway or node devices, if its something necessary you can assume some most suitable for the taskOnce i understand it enough then i will go further to buy devices and develop proof of conceptthanks,

author: sokoloff
author_rank: Super Contributor
timestamp: May 21, 2019, 09:00:28 pm
content: What you're asking about is a specific, detailed case of the general "how is collision detection/avoidance/recovery/compensation handled?"Unsurprisingly, there is research into the topic.https://fernandokuipers.nl/papers/WiNTECH2018.pdfis one paper I found, specific to the LoRaWAN collision performance and packet delivery rate.https://www.thethingsnetwork.org/forum/t/universal-lora-wan-gateway-limitations-because-physics/1749/12has a more simplified, easier to quickly grasp discussion of the topic as well. If your projected use falls well under that, you may not need to dive into the denser research paper.

author: sairfan1
author_rank: Frequent Contributor
timestamp: May 22, 2019, 04:17:21 pm
content: thanks, which lorawan gateway would you recommend

author: sokoloff
author_rank: Super Contributor
timestamp: May 22, 2019, 04:24:10 pm
content: Can't make a personal recommendation as I've only done single-channel proof-of-concept LoRa work so far.
Limiting current for solar battery charger help needed! - Page 1
Forum section: electronics / beginners

author: Meche
author_rank: Newbie
timestamp: July 11, 2017, 07:20:48 pm
content: Hi!I am currently building my own system to charge a battery with solarenergy. I will design my own MPPT and simulate it before building it.And here is my problem:The problem is that the MPPT will provide maximum power and lets say i get out 42V and 5A from the buck boost converter. And I would like to charge my Li-Ion battery that requires 42V and 2A.The 42V is okay but providing 5A to a battery that is specifed to 2A to charge is not good. The battery will drain current as much as it can. And I need to current limit the output from the buck boost converter with some electronics. I don't want to use something like an LM317, LM350 becauseit will generate a lot of heat.I 'ive done some reaserch and I have not found any thing concrete and I am turning to his community for some help.Is there any soulution to limit the current without generating a lot of heat? And if so how could I do that?Best regards

author: suicidaleggroll
author_rank: Super Contributor
timestamp: July 11, 2017, 07:22:58 pm
content: The current limit will be built into the MPPT. The MPPT will track the peak power point, up to the maximum output voltage and maximum output current it's designed for. In this case you'd design it to limit the current to 2A and limit the voltage to the float voltage of your battery.

author: Meche
author_rank: Newbie
timestamp: July 11, 2017, 07:28:34 pm
content: Quote from: suicidaleggroll on July 11, 2017, 07:22:58 pmYes but if I design it for 2 A and later would like to charge another battery that can handle more Amps it would be much better to have some control over the Amps. Lets say like the Imax b6 charger you can select how much Amps to charge the battery i would like to have same functionality if its possible?. I hope I am explaning it good enough.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: July 11, 2017, 07:41:05 pm
content: That's certainly possible, it just depends on how you're implementing your MPPT controller. For example the SM72442 uses a simple resistor divider on a 5V line feeding one of the pins to set the max output current. Swap the resistor and you have a different current limit, or you could have a mux or jumper to switch between several presets. If you're designing your own MPPT with an MCU and voltage and current monitoring, you could have a few different current limits pre-programmed that you switch between with GPIOs, or you could have a serial interface that lets you change current/voltage limits on command.
Current Limiting / Negative Voltage Regulator LM723 - Page 1
Forum section: electronics / beginners

author: RenE3
author_rank: Newbie
timestamp: November 29, 2016, 02:30:09 am
content: Hi folks,I'm trying to build a 0 to -15 V power supply with the LM723 but i get stuck trying to use the current limiter that the chip offers, i want a 1A Output, am i wrong in trying to use the current limiter in that mod. I will prefer not to use a external sensing transistor.Note: This is my first post and the first time that i use the LM723, is a very good ic but is somehow difficult.Thanks in Advance,

author: danadak
author_rank: Super Contributor
timestamp: November 29, 2016, 02:47:07 am
content: That regulator will not handle 1A with internal pass transistor, you needto use external power transistor. The datasheet has a number of externallyboosted circuits for consideration.http://www.ti.com/lit/ds/symlink/lm723.pdfRegards, Dana.

author: RenE3
author_rank: Newbie
timestamp: November 29, 2016, 03:11:09 am
content: Hi Dana,Thanks for your post, but i forget to put the picture of my circuit to give a better idea of what i'm doing.regards,

author: RenE3
author_rank: Newbie
timestamp: December 01, 2016, 06:34:07 am
content: I will expand my problem i think it is too ambiguous.I'm trying to design a split power supply with a LM723, i already builded the positive one,my problem is in the negative part, i want a negative supply with a variable voltage of 0 to -15 volts with a current limiter of aproximately 1A, i don't need 1A exactly. I already saw the datasheet but it only gives a figure (figure 18 and figure 23 of the datasheet above) with a pnp external pass transistor, i am not sure but i think that this configuration only gives more current and it will not limit the current.my circuit is in my first post, i already did physically and it gave me a voltage of -0.85 to -15 volts but when i turned the potentiometer to it's 0% (as in my circuit) the voltage at the output stays at 0.85v until i turned off and then on the circuit.another thing , i thought that putting the C.L and C.S pins (figure 19 and 22 of the datasheet) as show in the positives configurations would limit the current in the negative ones. that's why i was asking for and external sensing transistor.in resume my questions are:1) How i get variable negative voltage with the lm723? (I think that fixed one is easier because the datasheet says the values of R1,R2,R3 and R4.)2) It could get current limiter with a negative voltage configuration with the lm723 ?I will apreciate if someone know about it.Regards,
Limiting current spikes from load on DC power supply - Page 1
Forum section: electronics / beginners

author: canadaboy25
author_rank: Regular Contributor
timestamp: October 05, 2023, 05:26:45 pm
content: Hi all,I have a Hyperion EOS 720i super duo3 multi-chemistry battery charger that I am using to count capacity and verify condition of many small SLA batteries. The charger has an input range of 10.5V to 29V.Powering the charger from my lab power supply uses about 330mA at 24V. The charger operates perfectly on this supply.I purchased a VMS-550C-24 power supply rated 24V, 23A from Digikey. I made a fancy enclosure with a fan, switch, LED, and banana plug sockets to house the new power supply. Charging up the first battery seemed to go well until the charge was complete, and the supply restarted, resetting my charger.I plugged the charger back into the lab power supply and it was drawing 330mA at 24V for the entire charge. Once the charge was complete, the current dropped, and all of a sudden spiked for a fraction of a second - just long enough for me to see the constant current light flick on my 5A lab supply. After the very short current spike, it was back to 330mA.What appears to be happening is when the charger detects the battery is full, it stops charging, sounds the chime, and then starts charging again in trickle mode since these are SLA batteries. It seems that when the charger kicks back in, it draws a very short and large gulp of current. The current sense circuit on the power supply I purchased from Digikey must be detecting this as an overload and restarting.Since the charger has such a wide voltage input range, if I was able to limit the current spike, the momentary drop in voltage would not affect the charger. This is obviously true as the charger works fine on the lab supply when it briefly hits the 5A current limit.An inductor in series with the charger should limit current spikes, but how would I go about selecting an appropriate value for this inductor?

author: BillyO
author_rank: Super Contributor
timestamp: October 07, 2023, 07:17:56 pm
content: You'd need to know the impedance of the PS and the charger as well as the surge current to do it solely by calculation. However it might be something you could guestimate. Do you have a scope? Can you capture the voltage between the PS and the charger when the event happens? I'm assuming you don't have a current probe, but it would be nice to know the duration of the "glitch".Also, think about putting a reasonably large electrolytic capacitor across the output of the PS (470uF) as well as a .1uF ceramic then have the choke to the charger.One of those cheap automotive noise suppressors might do the trick.
Line 6 M13 Not Powering on. - Page 1
Forum section: electronics / beginners

author: morgs
author_rank: Newbie
timestamp: January 14, 2018, 12:57:08 pm
content: Gday all.Hoping for a little guidance here for my novice brain.I've tinkered with valve guitar amps in the past and have a basic understanding of some of those types of circuits, but I'm a little lost when it comes to solid state + digital stuff.So here I have my Line 6 M13 Modelling Stompbox. No worky.My first thoughts are start at the power rails and work from there.Have 9vac to D8-12. No dc after that.Diode test showed 0.574v one way, open the other. When performing this check they all tested short momentarily and I watched the voltage climb to 1.9v before showing open.Continuity test across capacitors c81,c84, c82,c85 + c80 showed open, but again initially were short until voltage increased and then showed open. If I repeat the test, they show open immediately, however if I reverse the leads it'll read short momentarily and then open.All these tests were done in circuit.I'm thinking my meter is charging the caps before they show open and this is effecting the diode readings also.I don't currently own an ESR meter ( ordered and on its way ) so I can't check the capacitors definitively.For the sake of a few bucks, I'll probably change them out anyway. They would be about 10 years old now.The rip out and replace option may fix the problem, but doesn't really help me understand what's going on.I'm guessing I don't really have all the test gear to fully diagnose the issue, but any guidance would be much appreciated.Hopefully my logic isn't too flawed, however I'm all ears and happy to learn, if that's the case.Cheers
line audio circuits for cat5 cable links - Page 1
Forum section: electronics / beginners

author: jonovid
author_rank: Super Contributor
timestamp: January 29, 2017, 01:08:03 am
content: I already have cat5 video links between rooms with good results.but now I d' like to add audio links too. A simple type of transformer circuit on the ends will do. but if active circuitry is needed?if I can have phantom power too, so much the better. if active circuitry is used, maybe a 50KHz or 1MHz carrier wave is needed for audio or FM on a carrier for cat5 ? . anyway high quality standard definition video, a somewhat complex signal works with just a passive pair of line transformers over up to 400 meters of cat 5. see image \/ .so im looking for audio circuits or transformer circuits that will do the same for audio 30 to 15,000 Hz over cheap Cat 5 twisted pair cable.this is for a integrated home entertainment & security system over 3 rooms and an outside garage.as just the line audio is missing, I d like some advice on. a good circuit or end units for audio over any cheap twisted pair cable.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: January 29, 2017, 02:09:58 am
content: I assume you are talking about low level stereo audio?You will probably need to change the signal from unbalanced, ie ground + signal to unbalanced for best results along the cat5. If you're not that concerned with hum you could just connect each signal pair to a pair within the cat5 cable. But if hum/interference might annoy you just use a coupling transformer at each end for each signal.https://www.jaycar.com.au/3kohm-centre-tap-to-3k-ohm-coupling-transformer/p/MM2534

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: January 29, 2017, 02:13:39 am
content: Or if you are lazy..https://www.amazon.com/Stereo-RCA-Audio-Extender-Over/dp/B00D2172MS

author: jonovid
author_rank: Super Contributor
timestamp: January 29, 2017, 03:34:48 am
content: its good to get a second opinion before you spend more $ on parts.yes is for low level audio over cat 5.as I already have low level audio type transformers. thanks!
Line following: Learning the track with encoders - Page 1
Forum section: electronics / beginners

author: Nexo
author_rank: Regular Contributor
timestamp: October 10, 2017, 01:46:06 am
content: Hello everyone!I've been reading that is possible to use magnetic or optical encoders in order to "learn" or "record" the track. Do you have any idea on how to do this?Thanks in advance!

author: ataradov
author_rank: Super Contributor
timestamp: October 10, 2017, 04:38:27 am
content: If your robot can already follow the line, then the track can easily be derived from the movement commands you gave to the motors. There is a matter of filtering and compressing the data, but this is really up to experimentation and depends on particular hardware anyway.
Line following robot sensor circuit - Page 1
Forum section: electronics / beginners

author: TheBadger
author_rank: Newbie
timestamp: September 20, 2010, 11:40:35 am
content: So I am building a robot to follow white lines and I just wondered if anyone had any advice on which is the best way to do the sensor circuit.I have been told to feed photo diodes into comparators, to feed photo transistors into hex schmitt triggers, to feed them directly into ADC converters and into the comparators on the PIC itself.getting a bit indecisive now, which is the best way?

author: Simon
author_rank: Unknown
timestamp: September 20, 2010, 11:45:43 am
content: some sort of light detection system (reflected light from the white strip) to compare with the rest of the surface, so comparators sound like a good idea fed into a pic that will control steering

author: Jochem
author_rank: Newbie
timestamp: September 20, 2010, 01:06:11 pm
content: This guybuilt a line following tank without using a micro, it might be fun to take a look at it. I think it follows black lines on white, but it shouldn't be too hard to have it follow white lines on black!
linear acceleration full scale ... meaning - Page 1
Forum section: electronics / beginners

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: August 27, 2015, 06:32:37 pm
content: Hi everyone, am building a board with an inertial module (3D accelerometer, 3D gyroscope, 3D magnetometer) all on the same package , and am trying to choose between LSM9DS1 and LSM9DS0, while the first one is clearly better in power consumption that's why am interested in and the for the fact that is a bit cheaper. i noticed a difference in a single detailThe LSM9DS0 has a linear acceleration full scale of ±2g/±4g/±6g/±8g/±16g, a magnetic field full scale of ±2/±4/±8/±12 gauss and an angular rate of ±245/±500/±2000 dps.The LSM9DS1 has a linear acceleration full scale of ±2g/±4g/±8/±16 g, a magnetic field full scale of ±4/±8/±12/±16 gauss and an angular rate of ±245/±500/±2000 dps.i don't understand the difference between them, what linear acceleration full scale of ±2g/±4g/±6g/±8g/±16g and magnetic field full scale of ±2/±4/±8/±12 gauss.Thanks

author: rollatorwieltje
author_rank: Unknown
timestamp: August 27, 2015, 07:14:20 pm
content: Usually with these devices you can scale the signals for the internal ADC. The ADC for example could be 10 bits, so your output ranges from 0 to 1023. You can configure the device so that -2g reads 0, up to +2g at 1023. This is useful if you need to detect small accelerations. However, if you accelerate the device at 10g for example, you will only read 2g, so choose your range carefully. If you configure it for 16G, you might not be able to detect small accelerations.Same for the accelerometer and the magnetic compass.The only difference in these modules seems to be the magnetic compass? Earth's magnetic field is less than a gauss at surface level, not sure why you would need more than 2 gauss sensitivity anyway. Maybe if you have a magnet near the sensor?

author: zapta
author_rank: Super Contributor
timestamp: August 27, 2015, 07:19:10 pm
content: Quote from: hamdi.tn on August 27, 2015, 06:32:37 pmIt's similar to the ranges of a manual DMM,. It allows you to select a range. A lower range gives finer resolution but also hits overflow at lower limit.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: August 27, 2015, 07:49:42 pm
content: Clear enoughthanks
Linear Actuators Redux - Page 1
Forum section: electronics / beginners

author: Dumpsterholic
author_rank: Regular Contributor
timestamp: February 10, 2018, 04:48:43 pm
content: Hi all:My diligence in scoping out a nearby Dumpster has paid off in the form of a complete controller circuit for a "Megamat MBZ 50899" linear actuator. Along with the LA itself, I also netted an "Ultra Control Box" and a "Pride" thumb switch. These circuits are used in power-lift recliner chairs for handicapped people, and every now and then a store close to where I work will throw away entire units: chair, control box and power switch. The LA's themselves and the controllers cost a bundle of money new, so when I finally got my unit home and tested it for functionality (Yay! It works just fine!), I was curious to find out what kind of fancy components might be inside.The answer: They comprise nothing more exotic than a transformer, some chunky diodes, a capacitor and a few resistors, plus a pair of relays. For some reason, there is also a pair of 9V batteries, even though the control box runs off of AC mains power. I suspect that planned obsolescence may be at work here, but so what? I'm not the one ripping off handicapped people (or the insurance companies that pay for their care); I just want to learn how to use LA's in microcontroller-based projects.So, here's my question: Given that a rectifier circuit and a couple of relays (one for forward, one for reverse?) are obviously sufficient to power a LA that can exert a push/pull force of 4,000 Newtons, why is there a need for more elaborate motor-driver circuitry in other applications? I suspect the answer is twofold. First, the units I scavenged have a very limited duty cycle of two minutes "on" and eighteen minutes "off", so in an application that required faster response times, the relay-based approach would not work because the relays themselves would quickly burn out.Second, these brute-force controllers make no provision for velocity or position control: The switch either makes them go forwards or backwards at one set speed, with no way to stop at a preset location. If an application required speed adjustment, then additional circuitry would be required to supply either a variable DC voltage or a PWM signal, and in order to tell the LA to stop at some desired position in the middle of its travel, other circuitry would be necessary to provide feedback to the MCU controlling the power supply to tell it when to turn on and off.Am I on the right track? It seems to me that with just the circuitry I have, all I would need to do to build a "Star Trek" style IR-activated sliding door is a microcontroller and a Darlington pair to fire the relays, plus whatever IR sensors would be required to tell the MCU when to activate the LA to do its thing. (Not to mention the mechanical parts: door, frame, etc.) Needless to say, there are many other possible uses for this kind of circuitry....
Linear Amplifier - Page 1
Forum section: electronics / beginners

author: GN89
author_rank: Contributor
timestamp: December 16, 2024, 07:58:19 pm
content: In my previous thread I posted a simulation of a linear amplifier which should work down to DC. I attached the schematic. The design requirement was to stack some mosfet to stay in a safe operation area of the mosfets. I did the tests with +-35V supply voltage. Later test will go up to +-120VThe first test was not successful because R44 was too large so the current source Q10,Q12,Q17 produced too much voltage over that resistor and the difference amplifier stage could not control the gate. I bridged the value for further testing.At this point I need your help. The first test was done without any load. A load of 500Ohm was tested after and the maximum output voltage clipped at a much lower output voltage. I will show scope results if you want.How do I increase the quiescent current? The voltage bewteen gates Q17,Q19 is about 7.3V for 0V input voltage at Q14 (Positive input). What happens when larger loads will heat up the output transistors? Is this design likely to drift with loads and destroy the output transistors?

author: CaptDon
author_rank: Super Contributor
timestamp: December 16, 2024, 11:59:22 pm
content: Study the multiple rail voltage class G amplifiers. The MOSFET's are stacked so to speak. Bob Carver had good success with the PM1.5 and PM-2.0T amplifiers using stacked output devices with multiple rail voltages. Just putting a bunch of devices in series to obtain a higher voltage swing from a single or bipolar higher supply voltage may not be so simple. But the reality is, this wheel has already been invented, no need to re-invent it. You should investigate the amplifiers that are actually a bipolar pair of variable power supplies connected to follow an input signal and so by description it is a tracking power supply and not truly an amplifier even though that is the job it performs!!

author: magic
author_rank: Super Contributor
timestamp: December 17, 2024, 08:18:33 am
content: Not sure what's the problem and not sure if raising quiescent current would solve it.Quiescent current will not be stable unless the drivers are thermally coupled to the output FETs.People build audio amps with MOSFET outputs so you could go and look what they are doing.Why a new thread for the same thing? I only vaguely remember what it was about...
Linear and Switchmode PSU's? - Page 1
Forum section: electronics / beginners

author: JakeC
author_rank: Newbie
timestamp: September 04, 2013, 06:38:19 pm
content: Hi,Could someone please explain what the difference between a switchmode and linear power supply is, I am very confusedThanksJake

author: mariush
author_rank: Super Contributor
timestamp: September 04, 2013, 07:04:16 pm
content: Really?https://www.google.com/search?q=linear+power+supply+versus+switching+power+supply&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

author: apbosh1
author_rank: Contributor
timestamp: September 04, 2013, 08:13:46 pm
content: why is it not called a PWM power supply?

author: rdl
author_rank: Super Contributor
timestamp: September 04, 2013, 08:36:35 pm
content: Dave actually did a tutorial on this subject.http://www.eevblog.com/2010/05/29/eevblog-90-linear-and-ldo-regulators-and-switch-mode-power-supply-tutorial/

author: Zbig
author_rank: Frequent Contributor
timestamp: September 04, 2013, 08:49:48 pm
content: Quote from: apbosh1 on September 04, 2013, 08:13:46 pmWith PWM you're actually getting variable-width pulses on the output. It's only good for powering some types of loads which wouldn't care much about that (some motors, heating elements, etc.) so you'll just get a more or less "averaged" result or where the easily-fooled human senses won't perceive the difference anyway (like the LED flickering at, say 400 Hz).With SMPS, you're getting true DC voltage or at least, that's what you're aiming for. The design is much more complex, for example there's a feedback loop involved - something you won't see in a PWM circuit.

author: apbosh1
author_rank: Contributor
timestamp: September 04, 2013, 09:03:04 pm
content: Thanks for clearing that up quickly Zbig.all the best.
Linear CCD (uPD3732) control - do I understand it correctly? - Page 1
Forum section: electronics / beginners

author: nikodem
author_rank: Regular Contributor
timestamp: September 12, 2020, 07:25:44 pm
content: I'm trying to understand how to interface this linear CCD to an e.g. Arduino.This is the timing chart of the interface:Nowhere I can find any information how to control the exposure time. Is TG responsible for that?Regarding the read - I clock the pixels with 1 and 2 clocks (sort of differentially), latch it with RB tied to CLB and then put SHB low, so I can read the Vout?
Linear DC Power Supply Design Book - Page 1
Forum section: electronics / beginners

author: markmckee601
author_rank: Newbie
timestamp: January 21, 2015, 10:34:50 am
content: I'm trying to find a good book with information about designing a Linear DC PSU. I can find loads about SMPS design. I live in the UK (Northern Ireland) and I'm also looking for some info about standards/regulations such as line filtering and testing.I hope to design, build and test my own lab PSU, eventually.Any help would be greatly appreciated

author: Syntax_Error
author_rank: Regular Contributor
timestamp: January 22, 2015, 01:38:45 am
content: http://sound.westhost.com/power-supplies.htmhttp://sound.westhost.com/articles.htm#s7Chapter 9 in:http://www.analog.com/library/analogDialogue/archives/43-09/linear_circuit_design_handbook.htmlAlso search the related app notes and design guides at the major manufacturers websites: Texas Instruments, Linear Technology, Analog Devices, etc. But I really would start with Mr. Rod Elliott's pages. He is a great writer and gives "the straight dope" as they say, much like Dave does in his videos.
Linear LTC2057XX - Page 1
Forum section: electronics / beginners

author: klaus11
author_rank: Unknown
timestamp: February 25, 2016, 02:33:00 pm
content: After reviewing the datasheet several times, I do not find the Peak output voltage (Vom). Can you help?http://cds.linear.com/docs/en/datasheet/2057f.pdf

author: RobK_NL
author_rank: Frequent Contributor
timestamp: February 25, 2016, 02:57:45 pm
content: I have no idea what you mean by "Peak output voltage", but as you can see on page 4 of the datasheet, the output goes to within 10mV of the supply voltage for a 'no load' condition.
Linear Power Supply -12VDC Shared /w AC Ground (Earth) - Page 1
Forum section: electronics / beginners

author: Mr Transistor
author_rank: Newbie
timestamp: July 07, 2022, 10:45:33 pm
content: Long time listener, first time caller. Yes, I already have the matching Dave bed spread and pillow cases.I am an electronics hobbyist and given this is my first eevblog post, please give me some grace and let me know if I am missing anything that may help you help me.I am building a UHF receiver and I am using a linear power supply because of its low noise/ripple characteristics. The PS has a 120VAC input and a 5VDC and 12VDC output. Below is a DK link to the PS I am using.https://www.digikey.com/en/products/detail/bel-power-solutions/HCC512-AG/1634144I have two questions. My first question is regarding the 120VAC input. The PS data sheet does not mention which terminal the live and/or neutral should be connected to. I am assuming that because it just goes to the primary of the transformer it doesn't matter which is live and which is neutral?My second question is concerning the 12VDC output which will power an RF preamp in the receiver. The preamp's -12VDC input is the chassis. Thus the receiver's chassis is -12VDC. But the receiver's chassis is also bonded to the 120VAC ground (earth). Can the -12VDC share the chassis with the 120VAC ground (earth)? Unfortunately the preamp's -12VDC cannot be isolated from the chassis.I appreciate any advice you have.Thank You,Manny

author: BeBuLamar
author_rank: Super Contributor
timestamp: July 07, 2022, 10:50:26 pm
content: I think it's fine provided that when you say -12VDC you mean that it's the negative terminal of the power supply and not a -12VDC potential in respect to COMMON.

author: Mr Transistor
author_rank: Newbie
timestamp: July 07, 2022, 10:57:32 pm
content: Quote from: BeBuLamar on July 07, 2022, 10:50:26 pmYes sir, by -12VDC I mean the negative terminal of the power supply.I suppose -12VDC could be taken as the PS has an actual -12VDC output. I'll be mindful of that in the future.Thank You,Manny

author: TimFox
author_rank: Super Contributor
timestamp: July 07, 2022, 11:19:29 pm
content: One should be careful about nomenclature:"-12V DC" normally means negative 12 V with respect to ground (chassis, common, low, whatever).A floating power supply, with 12 V between its negative and positive terminals, can be connected to make either -12 V or +12 V wrt ground.However, check to see if there is a common connection between the 12 V and 5 V power supplies contained in your unit.
Linear power supply mains transformer - Page 1
Forum section: electronics / beginners

author: Belrmar
author_rank: Regular Contributor
timestamp: September 09, 2017, 10:45:45 am
content: I want to build my own linear power supply , but choosing a mains transformer is getting a bit too complicated, and it gets heavy and expensive. So... is it a good idea to use a smps as a transformer andthen feeding that to the linear power circuitry?Tx for the help and i apologize for my bad english

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: September 09, 2017, 11:14:24 am
content: There is no reason not to do that, and it does eliminate some issues. The main objection is that SMPS tend to generate a fair bit of RF noise and so are less suitable for general bench testing.Other point is that linear PSUs tend to use transformer tappings to reduce heat dissipation. Unless you have a variable SMPS (and they are less common) then you have to put up with one input voltage to your linear reg. For a 30V 5A max output, that would mean dissipating 125W when operating at 5V, 5A. Which would call for a fairly beefy series pass.Also, use a SMPS with a decent safety approval such as TUV. Many of the no-brand ones are substandard in this respect, and you definitely don't want a short to mains on the test bench.

author: tooki
author_rank: Super Contributor
timestamp: September 09, 2017, 12:29:55 pm
content: Couldn't you theoretically use multiple SMPSs in series to achieve the same thing as transformer taps?

author: Cliff Matthews
author_rank: Unknown
timestamp: September 09, 2017, 02:28:04 pm
content: Theoretically yes, multiple SMPS can be stacked to do the same but use caution, some have mains coupled outputs. Also, the quality of galvanic isolation on some cheap SMPS transformers is at best questionable, so if you're going to stack them, your odds of failure may increase.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 09, 2017, 03:24:19 pm
content: In addition some SMPS (especially those without a PE ground) have class Y caps. Having several of these in parallel will at some point give to much capacitance / leakage.There are variable SMPS and also a few with multiply outputs, just like transformers with multiply taps.

author: not1xor1
author_rank: Frequent Contributor
timestamp: September 10, 2017, 05:53:55 am
content: Quote from: tooki on September 09, 2017, 12:29:55 pmyou could use a single AC-DC module plus a few buck or boost converters to get multiple fixed DC outputs referred to the same groundthen design the linear regulator as a sort of asymmetrical (unless you need current sink as well) class G audio amplifierBTW with the aid of a small negative voltage module you could build a real 2 quadrant PSU, able to sink current down to 0V