hybridfree/eevblog-posts huggingface dataset:
Control circuit for automotive wide band oxygen sensor? - Page 1
Forum section: electronics / beginners

author: G-son
author_rank: Regular Contributor
timestamp: May 15, 2024, 06:26:13 pm
content: I got a Denso 4 wire oxygen sensor (don't have part number here right now, I'll add it later) for some Subaru in a box of mixed parts, and earlier google searches say it's a wide band sensor, i.e. a sensor that can tell how rich or lean the engine is running, while the cheaper, simpler narrow band sensors just can tell if it's rich or lean, but not by how much. Basically, such a wide band sensor can be a great carburetor tuning aid and if possible I'd like to cobble up a control circuit for it so I can use it.Does anyone know how control circuits for Denso 4 wire wide band sensors work? It seems 5 wire wide band sensors are more common, but circuits for those probably don't help me much.Does anyone know how the heater control circuit determines the temperature of the sensor? I know the heater power is PWM regulated, but based on what? I think I've read somewhere that it uses the changing resistance of the heater to tell how hot it is, but I'm not sure and I've been unable to find the source again.Some info, but I'd like more:https://www.partinfo.co.uk/files/4%20Wire%20Wide%20Band%20Oxygen%20Sensors.pdf

author: G-son
author_rank: Regular Contributor
timestamp: May 15, 2024, 10:18:02 pm
content: The sensor is a Denso 22641 AA381, in case that info is helpful to anyone.

author: langwadt
author_rank: Super Contributor
timestamp: May 15, 2024, 10:38:08 pm
content: afair( it's many years since I looked into wideband O2 sensors) the temperature is determined by measuring the resistance of the Nernst cell using AC

author: G-son
author_rank: Regular Contributor
timestamp: May 16, 2024, 12:05:12 pm
content: That does seem correct.I'm getting a feeling this is a bit too complicated to cobble something up, especially for a sensor I can't seem to find proper data for.
control differences between Atmel 25DF041A and 25LC256 - Page 1
Forum section: electronics / beginners

author: djlorenz
author_rank: Contributor
timestamp: January 18, 2013, 11:46:25 am
content: hello,i'm studying the really good book Exploring Pic 32, where he explains how to talk with 25LC256 spi eeprom memoryi'm using the SURE Pic32 demo board wich has a Atmel 25DF041A spi FLASHlooking both datasheets seems they have the same pinout and the same control commands...i'm trying a simple program writing and asking the status register but i always get 255 for valuedo you know if i can use them in the same or need i change something?datasheets:http://ww1.microchip.com/downloads/en/devicedoc/21822e.pdfhttp://www.atmel.com/devices/at25df041a.aspxthank you so much

author: andersm
author_rank: Super Contributor
timestamp: January 20, 2013, 04:50:36 pm
content: First thing to check is that the peripherals and IO pins are configured correctly, then that your code operates the chip select line correctly.
Control El-Wire with FET - Page 1
Forum section: electronics / beginners

author: Apothus
author_rank: Contributor
timestamp: October 27, 2018, 05:09:18 am
content: As part of a project i am working on I want to control electroluminescent segments with a FET. I realise the typical solution is to use a flyback transformer to generate the high AC voltage and switch this with triacs. However I am trying to shrink my footprint and I have a lot of signals I wanted to control. My thought was to generate 200V DC with a boost converter, then switch each segment at ~1kHz with a logic evel signal driven FET.However... from what i understand the model of EL segments is a series resistor and capacitor effectively filtering the DC aspect of my circuit. So I am needing help in working out what I need to switch this load, my simulation skills and AC knowledge are sadly lacking.

author: mvs
author_rank: Frequent Contributor
timestamp: October 27, 2018, 08:06:02 am
content: Quote from: Apothus on October 27, 2018, 05:09:18 amEl wire is essentially a capacitor. To get some current throught it, you will need to apply AC voltage. So you will need at least half-bridge with some kind of gate driver (HV MOSFETs are usually not logic level) to make it glow.You can get TRIACs in TO-92 or SOT-223 packages, which will make you circuit small. Why to bother with MOSFETs for switching AC?

author: Apothus
author_rank: Contributor
timestamp: October 28, 2018, 09:31:42 pm
content: I want to drive 18 individual channels so 18 SOT-223 chips would take up a lot of real estate. So being able to get down to SOT-23 would have been a good step. The original idea for using FETs came from theHV509however I wanted to see if I could do it without the IC, especially considering the package it comes in (fussy arent I!). Although having looked at it further I see what you are saying about the half bridge and HV drive circuitry. Whilst it would be nice to have developed something from scratch I think this is another case of just use the IC
control high voltages with low votlages at base of transistor - Page 1
Forum section: electronics / beginners

author: abdulsamaddabu
author_rank: Contributor
timestamp: August 13, 2017, 07:28:58 pm
content: i was trying to control 12v relay using 5v singal at the base of BJT NPN transistor but its not workingit is giving output of 4 voltswhat the problem and how can i solve it ?thanks

author: Zero999
author_rank: Super Contributor
timestamp: August 13, 2017, 07:55:38 pm
content: The transistors are configured as emitter followers, so this is what you should expect to happen. The emitter voltage follows the base voltage, so the output voltage will be a diode drop, plus the saturation voltage, giving around 1V in this case: 5 -1 = 4VRe-configure the transistors as common emitters, with the emitters to 0V and the relays between the collectors and +12V.The diodes should have their anodes going to the negative side of the supply and the cathodes to the positive, so they don't conduct when the power is applied. You either have them connected differently to the schematic or they've blown them up, by passing too much current.
Control line voltage spikes, SRAM corruption - Page 1
Forum section: electronics / beginners

author: mosafet
author_rank: Contributor
timestamp: February 18, 2022, 11:28:14 pm
content: Sorry I created this schematic after the fact so it might not be 100% accurate. I have this simple SRAM circuit that switches between +5V power source and battery. The problem was that when the +5V power was disconnected/reconnected the SRAM would get corrupted.I can not remember if I had R3 or not when it wasn't working. Normally CE1 is controlled by external source same as +5V.On the oscilloscope when +5V power was applied the CE2 line had a 5ms rise time and as it got to around +2V it started going berserk with ±2V spikes and dips until about +4V then it stabilized. The voltage spikes were up to +6V, well above any power source!I switched R1 and R2 to 390 ohm and 10k respectively and the problem went away (may have added R3 too, I can't remember). CE2 now has a 1ms rise time and no weird variations.The problem is fixed but I'm curious about what was happening. What could be the source of the power spikes? I assume maybe U1 was oscillating or something as CE2 slowly came up to power, I don't know. I want to understand.

author: David Hess
author_rank: Super Contributor
timestamp: February 19, 2022, 12:15:44 am
content: The supply to the SRAM needs to be decoupled after the diodes.
Control loop of the switching power supply - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: February 18, 2025, 05:46:35 pm
content: How the control loop of the switching power supply dominates the tank circuit (output inductor and output capacitor)? And more importantly, why should the output tank circuit (L and C) dominate the control loop of the switching power supply?

author: PGPG
author_rank: Frequent Contributor
timestamp: February 18, 2025, 07:11:22 pm
content: Quote from: Freshman on February 18, 2025, 05:46:35 pmMay be other will understand what 'dominate' means here, but I don't.Do you think of for example that feedback loop can't protect output from getting higher voltage than it is set to when load is switched off. Energy stored in L have to go somewhere so LC decides what is going on and not feedback loop in such cases - someone can name it as dominating.Or do you think about which pole is at lower frequency?But if you were thinking of poles in feedback loop characteristics than you would start from specifying switching power supply operation mode (voltage mode, current mode, ...) you have in mind, but you didn't.I am using only one DCDC IC working in COT mode. I like COTs fast reaction to supply voltage changes and load changes practically in one pulse (current mode needs 5..10 pulses to notice that something has changed and need be corrected).
Control of BLDC with Raspberry Pi5 - Page 1
Forum section: electronics / beginners

author: HeinzKetchup
author_rank: Newbie
timestamp: August 25, 2025, 08:29:07 pm
content: Hello, I'm a complete newbie in circuits and have tried to figure it out with chatgpt (yeah, feel free to roast me!).I'm trying to control a DIA42B20W (BLDC motor with in-built driver) with a Raspberry Pi. Please see the diagram on how I plan to wire it all up. I have added a N-MOSFET into my circuit so that I can control the application of the 24V. The reason for this choice is two-fold:1)The warning below listed in the manual (See photo)"Prohibition of plugging and unpluggin while Power is ONUnplugging and inserting the connector in the power ON state may cause breakage, so please do not do it absolutely"2) To control the timing for the start up so that it matches recommendation in the manual (see diagram in Photo).Does the circuit make sense? I'm afraid I already fried one motor when I messing about in my first attempt, but I have ordered two more.Full manual for the BLDC is here:https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/2519/DIA42B20W32A_Spec.pdf

author: xvr
author_rank: Frequent Contributor
timestamp: August 26, 2025, 10:49:02 am
content: QuoteThis scheme will make everything worse. If you want to control +24V power you should commutate it, not ground. Use HiSide power switch (dedicated one or just P channel MOSFET)QuoteNot a good idea - you won't be able to get compensation from ChatGPT for burned out controllers and motors.

author: HeinzKetchup
author_rank: Newbie
timestamp: August 26, 2025, 12:31:23 pm
content: I've seen somebody apparently run this very BLDC motor with this circuit (Top figure) and with an arduino rather than a Raspberry Pi. But with my limited understanding of circuits then that circuit would not allow for controlled/timed application of the 24V and 5V power, or am I misundestanding how that circuit would work?The manual (Figure below) calls for application of the 5V to the in-built driver circuit prior to the 24V. In the ardunino code from that example there is a single comment about "- Voltage supply should be on before uploading/ initiating the program"

author: MariuszD
author_rank: Regular Contributor
timestamp: August 26, 2025, 12:41:17 pm
content: Quote from: HeinzKetchup on August 25, 2025, 08:29:07 pmNever disconnect the ground in a multi-voltage system, you'll fry your RPi.
Control panel indicator light, electric range, locating part. - Page 1
Forum section: electronics / beginners

author: DHeth
author_rank: Newbie
timestamp: March 22, 2016, 02:59:23 am
content: Hello everyone at EEVblog, long time watcher first time posting.I'm making a repair and having a bit of trouble trying to source one of the parts I need. It is a light bulb for an indicator lamp on an electric range/oven. I've found a few places selling the entire unit for $30 - $40 USD per piece and I need three of them! Seems a bit silly for just a few lightbulbs but I haven't been able to find a suitable replacement for the bulbs themselves.They are just small incandescents with the following specs:250V , 1/3Wdimensions 0.5" (13mm) by 0.25" (6mm)I have included some pics for reference in this album:https://goo.gl/photos/nEXGSBnkNtLA7heG9If anybody knows of some small bulbs like this or a good website to search for them at I would greatly appreciate it.Thanks, Dave.

author: bills
author_rank: Frequent Contributor
timestamp: March 22, 2016, 03:35:01 am
content: It's a ne-2 neon light.http://www.mouser.com/Search/Refine.aspx?Keyword=ne2+neonyou will need a ballast resistor.

author: DHeth
author_rank: Newbie
timestamp: March 22, 2016, 03:41:55 am
content: 220v didn't sound right to me for a lightbulb but I didn't see in any transformers in the control panel and it is a 220V electric range.I took my multimeter and measured AC voltage from the lightbulb terminal to earth and got 125V So there must be a transformer somewhere I can't see.I don't know why the bulb housing unit says 220v on it.The closest I can find are these 10 packs of 110v bulbshttps://www.grainger.com/product/LUMAPRO-Mini-Neon-Bulb-2FNB6?functionCode=P2IDP2PCPorhttps://www.grainger.com/product/LUMAPRO-Mini-Neon-Bulb-2FNC1?functionCode=P2IDP2PCP

author: DHeth
author_rank: Newbie
timestamp: March 22, 2016, 03:44:36 am
content: Quote from: bills on March 22, 2016, 03:35:01 amThanks!The bulb housing does have "external resistor required" stamped on it. So it probably has one inline already.

author: DHeth
author_rank: Newbie
timestamp: March 22, 2016, 04:02:00 am
content: Since I verified i'm working with 125V it looks like I need a 100K resistor for an NE-2http://www.shokaifareast.com/Products/Lamps/neon_selection_guide.htm

author: bills
author_rank: Frequent Contributor
timestamp: March 22, 2016, 04:06:01 am
content: Yes that is correct. 1/8 watt 100k

author: DHeth
author_rank: Newbie
timestamp: March 22, 2016, 05:18:19 am
content: Thanks for the help.Parts ordered.Thathttp://www.mouser.com/site is great. You can buy per unit, very reasonable prices and the searches actually give relevant results
Control question - Page 1
Forum section: electronics / beginners

author: steph
author_rank: Newbie
timestamp: April 22, 2022, 11:48:05 pm
content: Hi everyone my name is Steph, I'm a first year EE student. Just started control theory and I have been given a question on a heating system (water heater).I have created a block diagram of the system and reduced it to a single transfer function. I have been asked to work out what the temperature of the water is when 2 volts is placed at the input. From the attached you will find i'm getting two different answers; 40 degrees C from the reduced block diagram, and 20 degrees C from the final transfer function. My head is telling me that the reduced block diagram is the correct answer (because the feed back voltage = input voltage). However because i have just started control theory i'm not 100% sure which will be the correct answer. If i'm thinking wrong could you please explain to me why.Thanks Steph

author: Andy Watson
author_rank: Super Contributor
timestamp: April 23, 2022, 12:59:12 am
content: Add voltage (or temperature) values to your block diagram. In particular, note the "error" voltage at the node between the summation and the forward-gain section (K=20).Try it with output temperatures of 40 and 20 degrees - I think you will find that only the 20 degree senario gives consistent results.

author: steph
author_rank: Newbie
timestamp: April 23, 2022, 03:32:39 pm
content: Hi Andy.Thanks for that, I understand now
Control RPM motor - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 19, 2015, 10:16:21 am
content: 1. I have to control the rpm of motor. There is feedback in pulses by which I can see what is the rpm of motor.2. I am planning to do it by phase control.a. Read PWM signal of motor for 1 sec.b. Calculate the speedc. control the phase.d. go to step a.3. I am not able to control phase precisely. RPM of phase shows variation of +-40 rpm then what I set.4. What I have noticed is even if I give constant voltage 220vac directly, even then the rpm/pwm keeps of changing.5. Any other precise method to control rpm of motor. Motor runs on 220Vac. Its shaded pole motor
Controled gain Amplfiers - Page 1
Forum section: electronics / beginners

author: septer012
author_rank: Regular Contributor
timestamp: October 14, 2009, 05:49:22 pm
content: Might as well start off threads in this forum:Does anyone have any good info or links to Microcontroller controlled gain amplifiers? I am working on a simple design, two stage BJT common emitter amplifier and could use some info/research links as I need to drive a PWM Vsignal through the amplifier and get variable PWM Vout at 0-40v. Any thing on the subject can be helpful though, as the type of amplifier is not important as long as it can handle very low frequency.

author: JeffNichols
author_rank: Newbie
timestamp: October 15, 2009, 11:10:18 am
content: Microchip sells some PGAs (programmable gain amplifiers) that communicate with SPI. I don't think they go up to 40V, but you can always amplify the output.

author: Simon
author_rank: Unknown
timestamp: October 19, 2009, 04:26:24 pm
content: so basically you want to translate a 0-5 volt signla to a 0-40 v one ? use a mosfet

author: septer012
author_rank: Regular Contributor
timestamp: October 19, 2009, 10:02:28 pm
content: Quote from: Simon on October 19, 2009, 04:26:24 pmNo, amplification isnt the problem, finding a linearly adjustable gain amplifier is the problem.I think I might have found one:National Semiconductor LMH6502www.national.com/ds/LM/LMH6502.pdfWideband, Low Power, Linear-in-dB variable gain amplifier

author: Zsola
author_rank: Newbie
timestamp: October 12, 2013, 09:21:10 am
content: If you want to make variable gain amp, yopu should consider using SPI or I2C digitpots. They are cheap and nice, except the footprint of some devices, you can use it with a lot of, even precision opamps.Examples:http://ww1.microchip.com/downloads/en/AppNotes/01316A.pdf

author: sub
author_rank: Regular Contributor
timestamp: October 12, 2013, 10:32:14 am
content: A multiplying DAC might be a good choice as well, though I've not used them before.

author: tszaboo
author_rank: Super Contributor
timestamp: October 14, 2013, 04:08:14 am
content: Quote from: septer012 on October 19, 2009, 10:02:28 pmYou really don't want that amp for low frequency signals. It is designed for video and maybe radio. And I think you will not find any high voltage amplifier.If you amplify a PWM signal, do it before the filtering. Make multiple voltage rails, and use it for your PWM, as others stated it, use a mosfet. By increasing the resolution, you can reduce the number of rails (the output is just a voltage isn't it).If you really need a lot of amp. ratios, then make a fixed, 8x amp (5V MCU), or 12,5 (3,3V), and a variable voltage divider with digipot or a low voltage variable gain amplifier.

author: pinkysbrein
author_rank: Contributor
timestamp: October 14, 2013, 08:11:13 am
content: It's easier to split up the problem, modulate a power supply rail from 0-40 volt and then switch that. With the amplifier you have to worry about linearity over/undershoot etc ...
Controlled impdance, JLCPCB vs KiCad calcs - Page 1
Forum section: electronics / beginners

author: ifonlyeverything
author_rank: Regular Contributor
timestamp: June 18, 2023, 11:06:35 am
content: I'm trying to design my first controlled impedance PCB, a very simple USB isolator. This is USB 2.0 high speed so the spec is 90 ohms differential impedance. Signal will be on the top layer, followed by two inner ground pour layers, and an unused bottom signal layer. I punched this into JLCPCB controlled impedance calculator for JLC04161H-7628 stackup and I get this, a trace width of 0.1704 mm for the minimum supported trace spacing of 0.1016 mm.I punch this into KiCad's calculator (H = L1 + Prepreg + L2, per the JLCPCB layout) and I get a estimated 110 ohm differential impedance. This is about 20% too high vs 90 ohms target.To bring it down to 90 ohms I would need a trace width of about 0.306 mm. Who do I believe here?

author: PeteH
author_rank: Unknown
timestamp: June 18, 2023, 02:02:23 pm
content: The height value for the kicad tool....--- H = only the dielectric thickness between L1, L2.Also note that the dielectric constant of the FR4 being used by JLC is probably closer to 4.1-4.2

author: WatchfulEye
author_rank: Regular Contributor
timestamp: June 18, 2023, 02:32:49 pm
content: Did you get the dielectric thickness right in kicad? H should be the thickness of the dielectric only, not the trace/ref plane - i.e. 0.21mmFurther kicad does not calculate the effect of solder mask, which can be substantial. Using my home-made field solver and JLCPCB's solder mask specifications, for this scenario the soldermask reduces impedance by around 7-8 Ω.Results from my solver are (T = 0.035, W = 0.17, S = 0.10):H = 0.26, No solder mask: 103 ΩH = 0.26, Solder mask: 95 ΩH = 0.21, No solder mask: 100 ΩH = 0.21, Solder mask: 93 Ω
Controlled inverter - Page 1
Forum section: electronics / beginners

author: xue
author_rank: Newbie
timestamp: March 15, 2022, 01:52:04 am
content: Is there some kind of obscure IC that can be used as quad or even better octal controlled inverter?i need something like in this, but not quad xor, im running out of place on PCBAny help would be much appreciated, thanks.

author: xue
author_rank: Newbie
timestamp: March 15, 2022, 02:05:00 am
content: I know there is 7487 but it aint much help

author: Martian Tech
author_rank: Regular Contributor
timestamp: March 15, 2022, 02:20:26 am
content: GAL16V8?

author: Terry Bites
author_rank: Super Contributor
timestamp: March 17, 2022, 05:51:05 pm
content: Who can blow the fuses these days? DIYhttp://www.bhabbott.net.nz/atfblast.htmlcould work but the GAL has been discontinued.I thought of using an inverting and non inverting tristate buffer. Thats going to be bulky though.Redesign?

author: xue
author_rank: Newbie
timestamp: March 17, 2022, 11:30:47 pm
content: It was supposed to be simple '8 bit shift register -> xor-s with ne555 for lcd drive -> 7 segment LCD' thing.With cmos it takes absurdly low amount of power. I just cant fit it all on desirable PCB size eh. Ill think about it more.

author: Benta
author_rank: Super Contributor
timestamp: March 17, 2022, 11:38:56 pm
content: If that's the application, just use a CD4543/MC14543 LCD driver. Much easier.If you need a DP, a single-gate XOR can fix that.

author: Martian Tech
author_rank: Regular Contributor
timestamp: March 18, 2022, 02:41:56 am
content: Quote from: Terry Bites on March 17, 2022, 05:51:05 pmStill available from Atmel (Microchip) as ATF16V8. The TL866II can program themUnfortunately, the XORs are on the inputs to the FFs in Registered mode, so probably wouldn't work as a 1-chip solution for xue's application (if I understand his latest description properly)...Oh no, on further review it appears that the XORs cannot be driven from an input, but are just used to set an output to active high or low.
Controlling 2HP Treadmill Motor? - Page 1
Forum section: electronics / beginners

author: electromateria
author_rank: Regular Contributor
timestamp: August 10, 2021, 04:22:02 am
content: I have a 2HP treadmill motor, the ESC board, as well as what I believe to be a board that controlled the led display unit.How can I use the ESC to control the treadmill motor in the most simple way possible?Is it safe to dispose of the LED display circuit board?Is that cog looking thing on the back of the motor some kind of indexer?I have a second ESC that came off a smaller treadmill that had a burnt motor. Is it useful to keep or is it generally programmed for only that specific motor model?

author: Old Printer
author_rank: Frequent Contributor
timestamp: August 11, 2021, 03:23:55 pm
content: Do a Google search for information on re-powering small metal lathes and milling machines/drill presses. Treadmill motors are a popular choice for doing it on the cheap as they are plentiful. Many now use 3 phase motors with a VFD controller, but the DC treadmill motors were the most popular in the beginning, so there is information out there.

author: fcb
author_rank: Super Contributor
timestamp: August 11, 2021, 04:05:02 pm
content: Photonicinduction (YouTube) just released a video on treadmill speed control options..
Controlling 6 Pole Brushless DC Motor - Page 1
Forum section: electronics / beginners

author: ZeTeX
author_rank: Frequent Contributor
timestamp: January 11, 2020, 07:43:31 pm
content: Hello,I have 6 pole 300VDC brushless motor with hall effects.Would BLDH-350A Controller work? Here is the datasheet for the BLD-750:http://ican-motor.com/wp-content/uploads/2018/07/BLD-750.pdfIt seems like you can only choose between 2/4 poles. but on the BLDH-350A you have 4/8 poles.What is the difference between open-loop control and closed loop control? is it the feedback from the halls?Thanks.

author: Zero999
author_rank: Super Contributor
timestamp: January 12, 2020, 10:29:05 am
content: Open-loop = no feedbackClosed-loop = feedback
Controlling a adjustable table from uC - Page 1
Forum section: electronics / beginners

author: JJalling
author_rank: Unknown
timestamp: March 28, 2014, 04:30:31 pm
content: Hi,I would like to do a prank at a colleague by adding a wireless remote to his adjustable, table to control it.From the table comes three wires. +7V, up and down.Will my attached circuit work? If not, please feel free to comment and give ideas.Have a nice weekend!BR JonasEdit: Attachment rotated 180degrees - stupid iPhone
Controlling a Spot Welder with an aliexpress controller - Page 1
Forum section: electronics / beginners

author: FrankT
author_rank: Regular Contributor
timestamp: August 16, 2025, 11:41:57 pm
content: I'm trying to control a vevor spot welder...https://www.vevor.com.au/spot-welder-c_10076/vevor-portable-spot-welder-1-8-inch-thick-spot-welder-with-8kva-input-capacity-p_010212828859with an aliexpress microwave oven spot welder controller...https://www.aliexpress.com/item/1005004731273742.htmlI have the "100 amp" model which has a bta100-1200b triac to control the AC, 240VAC.I'm only interested in controlling the pulse length. I'm welding some stainless 1.2mm steel mesh to 3mm angle which needs less than 0.5s to weld it.Under a medium load, my hot air gun, the wave form looks as expected - chopped AC sine wave when not putting through 100%, and a full sine wave at 100%.However, when I run it through the spotwelder, I get a thumping noise from the spot welder and a distorted wave form...This is 20 AC cycles at 50Hz.Pulsing this by hand, directly connected to AC is fine; it's just hard to control for short periods.I don't know if the current draw is too high? Maybe the internal traces can't handle the current, I'm guessing 10-15A?Or is the spot welder, which is basically a big transformer - 240v in, 1.8v out, an inductive load causing issues - and this isn't the correct way to control it?Thanks,Frank

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 17, 2025, 11:43:25 am
content: It looks like it triggers on a few positive half cycles, and then a few negative half cycles, and then repeats.Does that (rebranded) "vevor" transformer / spotwelder have any electronics in it? It should at least have some kind of timer in it, and combining two different controllers on one spotwelder is never going to work properly.For the rest, it looks like you don't have enough experience to measure safely on mains connected equipment.Instead of controlling the primary of the spot welder, you can also use a 12V transformer, and then use the triac to control a resistor or incandescent light bulb. This is a pretty safe way to measure and experiment. One of the things you want to measure is when the TRIAC receives gate pulses, and whether it actually triggers on all of those pulses. These gate pulses also have a minimum current to trigger reliably, and you should verify that too.

author: FrankT
author_rank: Regular Contributor
timestamp: August 17, 2025, 08:36:18 pm
content: Yes, you are spot on about my lack of experience with mains equipment. I've been pretty nervous attaching probes to 240v.I don't think the vevor spot welder has any electronics. Just a manual switch on the primary side.I don't have the source code for the firmware, so I think I'll write this off, and cobble together a simple timer.
Controlling an LCD screen - Page 1
Forum section: electronics / beginners

author: CoopedUp
author_rank: Regular Contributor
timestamp: March 07, 2020, 05:49:21 pm
content: I have these 10.1" LCD screens from an Acer Iconia Tab A200 (B101EVT03 V.1) I have 18 of them, and I want to know how to hook it up to something to make a display. I know and have used LCD controllers for other screens but what I'm asking is, I can't find any controller that specifically says this LCD so is there some other way to get a controller for it. Its a 40 pin connector. Any help would be appreciated

author: amyk
author_rank: Super Contributor
timestamp: March 08, 2020, 04:55:19 am
content: See the datasheet:http://www.yslcd.com.tw/docs/product/B101EVT03.1.pdfIt's a standard 18bpp LVDS/FPD-linkpanel. Look for HDMI/DVI/VGA-to-LVDS converter boards if you want to make PC monitors out of the.

author: CoopedUp
author_rank: Regular Contributor
timestamp: March 12, 2020, 11:54:03 pm
content: Thanks for the help, ill look into that
controlling an lm317 - Page 1
Forum section: electronics / beginners

author: saipavan
author_rank: Contributor
timestamp: April 02, 2014, 08:31:38 am
content: i could not get a ten turn potentiometer to control an lm317. so i am trying to control an lm317 using an lm723 voltage regulator.is there a way to control the output of lm317 precisely using a couple of normal 10k pots ?Is it advisable to use an op amp(ua741) to control the lm317?thanks, in advance.......

author: mariush
author_rank: Super Contributor
timestamp: April 02, 2014, 09:49:36 am
content: The output voltage of your LM317 is determined by the formula Vout = 1.25 ( 1 + R2/R1) where R2 is your potentiometer and R1 is recommended to be in the range 120-240 ohm.For R2, you can have values between 0 ohm ( which gives you Vout = 1.25 x 1 = 1.25v) and as much as it takes to output about 30v... about 2300 ohm if you use a 100 ohm resistor for R1, about 5500 ohm if you use a 240 ohm resistor for R1.So if you use a plain 10kohm potentiometer, when you're at 50% on the potentiometer you're already at the maximum output voltage of the regulator. As you can see there's no way you get fine adjustment. Changing the 10kohm potentiometer with a 4700ohm one will allow you to see a voltage change on the output of the regulator on almost all range of the potentiometer (depending on what R1 resistor you pick in the 100-240 ohm range).A 10 turn pot will give you a lot of fine adjustment.If you don't have 10 turn pot, you can put two plain potentiometers in series, for example have a 4.7 kohm ohm one for rough adjustment and then put a 1kohm one for fine tuning.

author: hgg
author_rank: Frequent Contributor
timestamp: April 02, 2014, 09:53:31 am
content: Hi,Did you use the following configuration?Use a 4.7K pot, a fixed R1 and double check your connections.http://www.electronics-lab.com/articles/LM317/

author: saipavan
author_rank: Contributor
timestamp: April 02, 2014, 10:14:13 am
content: a multi turn pot is not available in my locality.so i decided to control the output voltage of lm317 with the help of voltage reference and an opamp.my lm317 is working with fixed resistors.can you suggest how i can use an opamp (741) to control the output of lm317???i want to get an output adjustable from 1.25 to 12 volts.(i am powering the circuit with a positive and negative voltage(-15 and +15 v) taken from a transformer).

author: homebrew
author_rank: Frequent Contributor
timestamp: April 02, 2014, 10:39:23 am
content: You could certainly do that. Just feed the sense-pin from the LM317 from the output of the opamp, bind the negative input of the opamp to the output of the LM317 and the positive input to your set voltage (generated by reference + pot).Supply the Opamp with +/- 15V and you will be able to span 0V-12V with that design.

author: saipavan
author_rank: Contributor
timestamp: April 02, 2014, 10:44:52 am
content: thanks guys it was of great help!!!!!
Controlling and driving multichannel LED - Page 1
Forum section: electronics / beginners

author: Ghost25
author_rank: Newbie
timestamp: September 13, 2018, 06:57:15 pm
content: I'm interested in building my own LED aquarium light for growing coral. I'm basing my design off of one model called the AI Prime HD. Here's some info from the manufacturer:https://www.advancedaquarist.com/blog/ai-prime-hd-info-packetMaximum power is only 55W but it has 7 independently controllable color channels which you control over WiFi and it has a really small package. My question is how are they able to fit the power supply into such a small space and also control 7 color channels?Here is a teardown of one that I found and there are clearly 7 SMD around the perimeter:Are these N Channel mosfets being controlled by a WiFi enabled microcontroller? All the LED drivers that run of 120V AC are quite large, almost as big as this entire light. What's the best way to do this and would it also be scalable for a larger device?

author: Ghost25
author_rank: Newbie
timestamp: September 13, 2018, 08:11:17 pm
content: OK I did a bit more research and it seems they do have an external power supply, around 24V and 2.5A DC. But the question remains, are the channels controlled by individual DC-DC LED drivers or by some other mechanism?

author: Eka
author_rank: Regular Contributor
timestamp: September 14, 2018, 01:17:16 pm
content: Likely resistors to control the current for the strings of LEDs. Multiple strings will be used for each color.Each color of LED likely has a N-channel FET to turn it on and off real fast for dimming.Add a fet driver per channel to get the fets to turn on and off fully.Next is the MCU and wifi.Yeah, that simple.
Controlling ATX motherboard power w/ microcontroller - Page 1
Forum section: electronics / beginners

author: PriorUniform721
author_rank: Newbie
timestamp: August 07, 2015, 10:27:54 pm
content: Long time viewer, first time poster.I have a project where I want to be able to turn on/off/reset an ATX motherboard remotely with a microcontroller.My requirements are:Keep the power/reset buttons and power LEDWork with any ATX motherboard (I want to open source the designs)Be powered by ATX PSU (share motherboard ground)Use the power LED as an input to the MCUI've done some experimentation with a couple of boards and even in my two I have some variation. One board seems to provide 5V to my LED and the other 3.3V. I can't find a clear definition of how the switches are to be wired nor the specs for the power LED. So I've designed my circuit to operate in parallel with the pin headers on an ATX motherboard. I suspect though that power+/reset+ are pulled low by the switches. But I just can't confirm this.The circuit I've come up with is attached.Let me explain my thinking about the schematic.Power SenseThe gate of Q1 is attached to the power LED via a current limiting resistor R3 and a pull down resistor R4. The drain pin of Q1 is pulled up to +3.3V (the voltage of the MCU) with R2 and connected to an input on the MCU. The drain pin is connected to ground.Power/Reset SwitchesThe emitter and collectors of Q2 and Q3 are connected in parallel to their respective switches. The bases of Q2/3 are connected through R5/6 to two MCU outputs which are internally pulled up to 3.3V. (I was considering pulling them up to 3.3 externally so that if the MCU is off their state is known.)The questions I have are:Does it matter if the gate of Q1 is on the anode or cathode side of the power LED?Do I need a current limiting resistor for Q1?Does the orientation of Q2/3 matter with respect to the reset+/- and power+/-? (Because you normally place emitter on 0V side and load on collector side)Should I instead be pulling power/reset up/down myself with the MCU directly?Is there a better (more compatible, no polarity considerations) way to do this?How could I modify this to use the switches as inputs to the MCU also? So that I could sense when the MB is reset manually?What I would like to do is have a set of pin headers on the board and simply jumper the pairs from the motherboard to my board and then attach the switches/LED directly to my board in parallel.Please help, thanks in advance,-Alan
controlling color leds with a potentiometer? - Page 1
Forum section: electronics / beginners

author: AwesomePixelMan
author_rank: Newbie
timestamp: February 20, 2014, 07:27:06 pm
content: Hi there!I am currently working on a small dc poweradapter that outputs 16A on variable voltage between 1.4V and 1.8V. The main component is a TI step-down (PTV12020LAH) with a max. of 16A and a Vadjust pin that measures resistance to ground to set the voltage. That's where the poti comes in; it's value is given by the step-down, namely 10k. All of this is going to fit inside a small cnc'd woodden box, featuring a band of light (3mm plexi with leds to light the sides) that should change colour based on the setting of the poti/ variable resistor . If it's value is zero, and the voltage is low, green leds should be lit, and when the resistance is set high, likewhise the voltage, red leds light up. The change in color in between should be gradual and when power is applied the leds should fade on in about a second and fade out when the unit is turned off. I have a swich that grounds a pin on the buck module as a soft on/off. I currently have installed some green leds, but they don't fade in.The device is powered by a regular 12V dc wall wart.I do not have too much knowledge yet, in fact, this is my first ever project! My equipment isn't too good either, so smd stuff is a bit tricky to do for example.How can I cheaply and easily achieve this?Here is a picture:
Controlling "current limit pin" on LT3045 with a DAC - Page 1
Forum section: electronics / beginners

author: Solberg
author_rank: Contributor
timestamp: August 22, 2020, 06:35:26 pm
content: HiI have been trying to figure out, how to control the current limit on the LT3045 LDO with a DAC.I just can't figure out how to.Can anyone help?I have attached the LTspice simulation i am playing around with.https://www.analog.com/media/en/technical-documentation/data-sheets/LT3045.pdf

author: Manul
author_rank: Super Contributor
timestamp: August 22, 2020, 07:43:10 pm
content: You mean voltage controlled current limit? Theoretically you may be able to do it with JFET, but it will not be accurate or stable.Probably your best bet is simply a digital potentiometer in place of current limit set resistor. Or use a different regulator IC.

author: Solberg
author_rank: Contributor
timestamp: August 22, 2020, 08:20:06 pm
content: HiI was playing around a bit more, and found this solution.0 volt on V3 gives 150mA0.1 volt on V3 gives 100mA0.2 volt on V3 gives 50mA0.3 volt on V3 gives 0mAThat gives me the equation: y=-0.002*x+0.3x=mA outputy=voltage on V3Do you think it is a stable solution?

author: Manul
author_rank: Super Contributor
timestamp: August 22, 2020, 08:58:25 pm
content: Yes, that looks like a nice solution if you are allowed to drive that pin (I guess so). Good job. Lower resistor does nothing and can be removed.

author: David Hess
author_rank: Super Contributor
timestamp: August 22, 2020, 11:50:50 pm
content: The current limit activates when the pin reaches 300 millivolts and the source current out of the pin is 1/500th of the output current, which leaves several methods to adjust it.The voltage at the bottom of the pin can be raised like Solberg suggests although it may be difficult to control at the lowest voltages without a negative bias supply.I was thinking that the resistor could be replaced with a current sink which sets the current limit. When the source current is high enough, the current sink comes out of saturation and reaches 300 millivolts with high DC gain. The problem with this is that it may not be stable, and a clamp would be needed to keep the current sink out of saturation.I think the best way is to *add* a current to the current source so that the 300 millivolt threshold is reached sooner. So the resistance sets the maximum current, and the added current lowers the amount of current from the pin necessary to reach 300 millivolts. This could also be done using a voltage source and resistive divider. The disadvantage is that ia higher current, or higher voltage, lowers the output current limit.
Controlling heating elements - Page 1
Forum section: electronics / beginners

author: aaronhance
author_rank: Regular Contributor
timestamp: December 09, 2015, 05:23:10 am
content: Hello eevblog forums! I was wondering what would be the best way to control a heating element with an mcu? I would like to be able to achieve and sustain a set temperature, with the help of a sensor of-course.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: December 09, 2015, 05:44:53 am
content: 1. What voltage for the element?2. What power of the element?3. What type of temperature feedback?4. What process parameters - stability, heat-up time, etc.5. Ambient conditions?

author: Richard Head
author_rank: Frequent Contributor
timestamp: December 09, 2015, 05:59:09 am
content: It depends on your intended level of accuracy of the setpoint temperature and the thermal time constant of the thermal mass.If you require sub 1 deg C stability then you probably require proportional control (ie thyristors/triac with phase control).If your setpoint stability isn't too critical you can use bang-bang control and use a relay to switch the element on and off. This is the most popular type and most industrial controllers use this technique.If you go for proportional control then I would be inclined to use an analog control loop and a micro with PWM (or DAC) to generate the adjustable setpoint voltage.If you go for bang-bang control the the micro can do everything. Just remember to include some hysteresis or the relay will open and close very often.

author: aaronhance
author_rank: Regular Contributor
timestamp: December 09, 2015, 06:04:07 am
content: Quote from: Tomorokoshi on December 09, 2015, 05:44:53 am12v, 150w and 30w heaters.thermistors+/- 10*C for 150w, +/- 5*C for 30wroom temp 18*C - 26*C~
Controlling laser modules - Page 1
Forum section: electronics / beginners

author: Kemme
author_rank: Contributor
timestamp: December 04, 2020, 07:10:53 am
content: HelloI've just received an aliexpress laser module. It was supposed to be 5.5w which would allow me to cut 1,5mm paper but it barely scratches it when I try to run it on full power.It is probably one of those cheap fake lasers but maybe I am doing something wrong?Here's a link:https://www.aliexpress.com/item/1005001349089109.html?spm=a2g0o.productlist.0.0.1d1a48704WzPY8&algo_pvid=7d582763-2093-4a42-a491-99d9598b58e8&algo_expid=7d582763-2093-4a42-a491-99d9598b58e8-7&btsid=2100bde116070650575731029e756d&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_All I know is it works with 12VDC. It has three cables (red, yellow and black), I connect 12V supply to red and black and I use PWM on yellow one. PWM is 3.3V, is it possible 3.3V is too low? What frequency PWM do such lasers usually require?
Controlling led strip with a uC  - Page 1
Forum section: electronics / beginners

author: 24ariel3
author_rank: Contributor
timestamp: November 08, 2018, 01:23:52 am
content: Hi,I want to control a 12V 100mA led strip with a microcontroller, what is the best way to do it, darlington transistor, MOSFET or other way?Thanks

author: macboy
author_rank: Super Contributor
timestamp: November 08, 2018, 04:31:48 pm
content: NPN transistor: emitter to ground, collector to the - side of the LED strip. LED strip + connected to 12 V supply +. Connect 1 kOhm resistor from micro output pin to NPN base pin. Output high = LED On. 12 V and micro (5 V?) must have their ground (-) connected together. Use any 'jellybean' NPN like 2N2222, 2N3904, BC547, any of them can handle 100 mA when saturated.

author: 24ariel3
author_rank: Contributor
timestamp: November 08, 2018, 04:35:03 pm
content: What about voltage drop over the npn, won't it make the led strip abit dimmer?(The uC is 3.3V)

author: macboy
author_rank: Super Contributor
timestamp: November 08, 2018, 04:53:27 pm
content: Drop will be equal to VCE(sat)at 100 mA, which should be around 0.35 V.If that is a problem, then you can replace the NPN with a small logic-level N-channel MOSFET, as long as the output voltage of the micro is higher than the turn-on threshold of the MOSFET, and keep the RDSONlow (like < 1 ohm) to minimize voltage drop. Something like BSH103 would work. They cost more than a simple NPN, and its a SMT part.

author: 24ariel3
author_rank: Contributor
timestamp: November 08, 2018, 04:58:46 pm
content: Mosfet sound good.What about SSR or is it an overkill?When to consider to use SSR?

author: brybot
author_rank: Contributor
timestamp: November 08, 2018, 06:58:56 pm
content: A SSR could work, but is probably overkill. You can use a SSR like a mechanical relay where you are using a small signal to switch a larger one, or a DC signal to switch AC. In your case a BJT or FET is cheap, simple and will do the trick. SSRs usually use some combination of FETs or TRIACs, depending on the application. In some cases, they can also isolate the signal and load, but that probably isn't a concern in your application.
Controlling multiple servos - Page 1
Forum section: electronics / beginners

author: Youkai
author_rank: Regular Contributor
timestamp: August 01, 2022, 03:18:16 am
content: I'm working on a project where I anticipate needing to control 6 servos, in addition to a number of buttons, and some RGB LED's. My plan for the project is to use the smallest board with enough IO pins. Maybe a Sparkfun Pro Micro if that will work. I've heard that controlling servos from Arduino can be janky due to interrupts/timing/whatever.So I'm wondering if I need to use a servo controller board similar toPimoroni Servo 2040. If so does anybody have recommendations for boards? I think 6 is probably the number I'll need but it definitely won't go above 8 or 10 servos.If I use a servo board in addition to my main micro-controller, I assume it's possible to send commands from the MC to the Servo board, correct? I.e. trigger moves of the servos from button presses detected on the MC.

author: pcprogrammer
author_rank: Super Contributor
timestamp: August 01, 2022, 04:26:09 am
content: You can try this board:https://nl.aliexpress.com/item/32710084048.htmlHave such a board, but have not tried it myself yet. The same chip is used by Adafruit:https://www.adafruit.com/product/815so plenty examples will be available.