hybridfree/eevblog-posts huggingface dataset:
Calibrating temperature sensor on a PIC MCU (equations) - Page 1
Forum section: electronics / beginners

author: npelov
author_rank: Frequent Contributor
timestamp: November 14, 2016, 03:16:09 pm
content: Hi,(Before you say it - I don't need accuracy. +/-5 deg. C would be ok.)I wanted to ask for the equations deriving the calibration equations for internal temperature sensor (few PN junctions in series with CC drive), but I think I got them. I'll still post this forsanity checkandoptimisationsuggestions (I know there are a lot of optimisation gurus here!)I tried consultingAN1333, butmicrochip overcomplicate things. I don't really care about diodes voltage. All I care is the relation between ADRES and temperature. So that could be done with one simple equation:(1)Temp = A + ADRES*BAnd because I want to avoid floating point and division I want to do it like this (B=B1/B2):Temp = A + ADRES*(B1/B2), where B2 is exact power of two (2^8 or 2^16 would be even better - no shifting required). In other words if A is 473 and B is -3.61,then B1 would be -3.61*65536 = -236585 and B2 would be 65536. So the equation would be:Temp = 473 - 236585*(ADRES << 16) (of course I'll use union to set the high bytes of a unsigned long to ADRES instead of shifting 16 times)So I need to calibrate A and B1 from two temperature points.Let's say I measured:ADRES1 = 133 at T1 = 5 deg. CandADRES2 = 151 at T2 = 70 deg. CI need to calculate A and B1 (or we can say it's B1 = B<<16). So I derived this:A = T1 - ADRES1*BB = (T2-T1)/(ADRES2-ADRES1)or B1 = B << 16Let me know if I'm wrong or if something can be optimized. Now it would be nice if I can avoid division in calibration - I'm not sure if I can get all the code into a PIC12F1571. But I'll worry about that when I'm out of ROM.
Calibrating time measured on pulses received - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 23, 2015, 10:14:22 am
content: 1. I have to measure time between two pulse signal coming on two pins.As soon as rising edge comes on pin 1, I start the timer until second signal on other pin.So basically time measurement is done between signal on two pins.2. Code iswhile(1){rest all paras;configure timer;wait for pulse on pin 1;start timer;wait for pulse on second pin; /* when pulse comes on second pin, EXTI ISR read the timer value */}3. When I give 1us pulse diff on two pins, on first iteration of loop, I read 1.383us & for subsequent loops I read 1.35us.(i.e when loop runs for first time)Similarly for 11us, on first iteration of loop, I read 11.383us & for subsequent loops I read 11.35us.Similarly for 111us, on first iteration of loop, I read 111.383us & for subsequent loops I read 111.35us.Similarly for 500us, on first iteration of loop, I read 500.383us & for subsequent loops I read 500.35us or 500.717us.4. I don't understand why error on first pulse.5. Is there any method for calibration for measured time also or best way is to do the subtract the offset.6. External pusles are generated at same pulse via another MCU.

author: Rerouter
author_rank: Super Contributor
timestamp: February 23, 2015, 10:47:41 am
content: how about you approach the problem differently, keep the timer always running in the main loop with a counter to handle rollovers, use an interrupt for both pins, each will enter, save the current time to a volatile variable, then exit.in the main loop check to see if either varibale has updated, if so record it and the count of overflows, and recalculate your new reading, (you may want to also check for timeouts)this should make your ISR's very consistently timed, and leave more time to measure smaller pulses,

author: SL4P
author_rank: Super Contributor
timestamp: February 23, 2015, 11:18:26 am
content: +1 to this approach
Calibration standards DAkkS and ISO - Page 1
Forum section: electronics / beginners

author: T.D.
author_rank: Newbie
timestamp: January 27, 2019, 04:50:48 pm
content: Hello forumRecently i saw bench power supplies which are available calibrated either ISO or DAkkS (German standard?).Could please someone explain the differences between these two ISO and DAkkS?Thank youT.D.

author: mvs
author_rank: Frequent Contributor
timestamp: January 27, 2019, 09:21:30 pm
content: Quote from: T.D. on January 27, 2019, 04:50:48 pmDAkkS calibration follows ISO 17025 but has better tracebility (less cal. transfer steps to national standard at PTB) and rules are a bit more strict then ordinary ISO factory calibration.

author: T.D.
author_rank: Newbie
timestamp: January 28, 2019, 07:48:10 pm
content: Thanks for explanation.TD
Calling Analog Experts - WEMOs LiPo Shield Help - Page 1
Forum section: electronics / beginners

author: McGovernR
author_rank: Newbie
timestamp: February 21, 2018, 11:11:42 pm
content: Hello EEVblog community,Glad to be here. I have a question regarding some circuitry on the WEMOs Battery Shield. Below is a screen shot of the circuitry. Vbus is connected to the board's charging input (USB) and +5V supplies 5VDC to the Wemos D1 mini AND is connected to the output of the charging chip.I'd like to understand fundamentally what is happening with this circuitry. To me, it looks like some sort of protection circuitry, but why use a matched PNP transistor pair with a FET.Link to complete circuit:https://wiki.wemos.cc/_media/products:d1_mini_shields:sch_battery_v1.2.0.pdf

author: danadak
author_rank: Super Contributor
timestamp: February 22, 2018, 01:33:07 am
content: Explanation over here -https://www.eevblog.com/forum/projects/power-injection-protection-on-vdd-output/Regards, Dana.
Calling young engineers! - Page 1
Forum section: electronics / beginners

author: 8163jb
author_rank: Contributor
timestamp: December 15, 2013, 06:58:45 pm
content: Are you a young engineer? Do you want somewhere to showcase your talent? Do you have a cool project you want to share with the world? I'm putting a section on my website for young engineers to share their projects, sound interesting?http://doayee.co.uk/calling-young-engineers/
Cam getting blinded by the light - Page 1
Forum section: electronics / beginners

author: Wplars
author_rank: Newbie
timestamp: January 12, 2015, 03:57:06 pm
content: Heya,Im running a Wordpress company together with some friends. Our office got one of the most amazing views in Stockholm and we thought it could be a great way to market ourselves. We had a webcam on our office filming some stuff on the office but mainly our amazing view. During 8-11am the sun reflects in the water and totally ruins the picture. It takes a few hours before the picture is back to normal again. Blurry, bright, pixel'd...Can anyone explain this for us? If anyone can explain this properly and come up with a solution how we can get rid of this problem, we'd be more than happy to design you a simple web site. Justdrop us a msgor here...Cheers!

author: Yago
author_rank: Frequent Contributor
timestamp: January 12, 2015, 04:13:59 pm
content: Could try a polarising filter in-front of the lens, rotate until max attenuation of reflected light.A lens hood too will help reduce flare from other off angle light.

author: katzohki
author_rank: Frequent Contributor
timestamp: January 12, 2015, 04:16:52 pm
content: Yeah I was going to say the same thing, polarising filter and lens hood.

author: Wplars
author_rank: Newbie
timestamp: January 12, 2015, 11:25:50 pm
content: Quote from: Yago on January 12, 2015, 04:13:59 pmThanks Yago! We will definitely take a look on this!

author: Rick Law
author_rank: Super Contributor
timestamp: January 13, 2015, 12:19:01 am
content: Just like a magnifying glass can burn a hole on a piece of paper by focusing the sun on it...If your camera is in the line of sight of the sun and the sun is at-times visible on the screen, be mindful that it may burn your chip. Typically, USB/Web cam doesn't have a shutter to block when not imaging. So the focused sun will stay at one spot on your CCD for long enough to possibly cause permanent damage.
CAMA-AFM31 USB Capacitive Fingerprint Module with FPC1020 pin configuration - Page 1
Forum section: electronics / beginners

author: akashmittal
author_rank: Newbie
timestamp: April 09, 2017, 01:50:04 pm
content: I have a CAMA-AFM31 USB Capacitive Fingerprint Module with FPC1020. I am new to it and i cannot figure out what its pin configuration is. I have searched everywhere but am unable not find its datasheet. I just need to figure out its power, ground and tx/rx pins.Please can someone provide me with some help? I have attached the necessary pictures of the module.Thanks in advance.

author: amyk
author_rank: Super Contributor
timestamp: April 09, 2017, 03:13:07 pm
content: Do these help?http://www.shenzhen2u.com/doc/Module/Fingerprint/710-FPC1020AM_B.pdfhttp://www.shenzhen2u.com/doc/Module/Fingerprint/710-FPC1020_PB3_Product-Specification.pdf

author: akashmittal
author_rank: Newbie
timestamp: April 10, 2017, 10:11:36 am
content: Thank you for your replyActually I have the documentation for the fpc1020 fingerprint sensor, and I require the documentation of the module (CAMA-AFM31). As the fingerprint sensor is already programmed and connected to the module, I only need to figure out the pins of the module (CAMA-AFM31).
Camera (with ISP) + WiFi - Page 1
Forum section: electronics / beginners

author: s0l4n1
author_rank: Newbie
timestamp: July 05, 2020, 01:01:23 pm
content: Hi,I'm trying to build a micro camera that will be able to show video-on-demand while connecting to it from the phone / PC.It's possible to build it using Arduino (and others boards) but it looks like an overkill for this task. All I need is just camera module (preferably with good optics and characteristics) + ISP (to build images from camera module) + power supply + wifi transmitter. The smallest thing I've found so far is ESP-32 Cam module but it still looks like an overkill (with SD card, bluetooth, pinouts) and, that's why, it's too big.Do you know of any alternative solutions to build my model?Thank you for your help.
Camera Flash Charge Circuit Sound Simulator - Page 1
Forum section: electronics / beginners

author: zcomputerwiz
author_rank: Newbie
timestamp: May 07, 2020, 04:49:58 pm
content: I'd like to build something to simulate the sound from noisy transformers in old flash capacitor charging circuits for a prop.Looking at a generic flash capacitor charge circuit, could I replace the transformer and high voltage capacitor with a speaker and large low voltage capacitor with a couple more transistors for feedback?I think I'd only need a speaker, 3 transistors, one diode, a large capacitor and two small capacitors with the right resistors to make something that oscillates faster as the charge in the large capacitor builds, but I don't know how to find the values required for the capacitors and resistors to get the sound I want.Anyone have suggestions for reading material to figure this out on my own, or could walk me through it here?

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: May 09, 2020, 11:20:06 am
content: Not sure the exact circuit you have in mind, but driving the speaker might dissipate the power that would otherwise go into charging the capacitor.Since it's for a prop, maybe just use a Raspberry Pi as a tone generator?

author: Circlotron
author_rank: Super Contributor
timestamp: May 09, 2020, 12:34:02 pm
content: If you need a bit of volume, get an actual flash and place a pickup coil near the transformer and feed this to an amplifier and loudspeaker.

author: themadhippy
author_rank: Super Contributor
timestamp: May 09, 2020, 01:21:59 pm
content: use one of those greeting card chips and record the actual sound, add a small chip ampfor a bit more umph
Camera stabilizer motors question - Page 1
Forum section: electronics / beginners

author: Karamel
author_rank: Regular Contributor
timestamp: September 19, 2016, 08:31:46 pm
content: Hi everyone,I am really interesting with camera hand 3 axis stabilizer like below photo. Firstly, I was thinking that there are some servo motors but, then, I looked forward something on internet and I got it they use brushless motors like thathttps://tr.aliexpress.com/item/2805-140kv-Brushless-Motor-Hollow-Shaft-for-3-axis-Storm32-Brushless-Camera-Gimbal-GOPRO3/32553402119.html?spm=2114.010208.3.1.QT4iAL&ws_ab_test=searchweb201556_8,searchweb201602_3_10057_10056_10065_10068_10055_10054_10069_301_10059_10058_10032_418_10073_10017_10070_10060_10061_10052_10062_10053_10050_10051,searchweb201603_2&btsid=9fb21006-c621-40d7-901e-0d10cdec244bNowadays, I am also ineresting with rc planes which have electric brushless motor but I known that brushless motors are fast and have nice torque but are useless at sensevitive motion(as step motors or servo motors) however, as we see, they are good at micro step motion or sensetive angle motion.So, I am wondering that how can I drive these motors? and how can I turn them like micro-step step motors?Best Regards,Karamel

author: Karamel
author_rank: Regular Contributor
timestamp: September 20, 2016, 03:29:20 pm
content: No any idea?

author: senso
author_rank: Frequent Contributor
timestamp: September 20, 2016, 04:48:44 pm
content: With roll your own 3-phase drivers, or with lots of different chips made for that.They are soooo common in the RC world.http://www.rcgroups.com/forums/showthread.php?t=1829058http://www.instructables.com/id/DIY-Brushless-Gimbal-with-Arduino/

author: Karamel
author_rank: Regular Contributor
timestamp: September 20, 2016, 11:28:25 pm
content: I really did not understand how i can do it because, I had rotated brusless motor with my hand and with esc controller. Thus, there were, maybe, ten step and this is 36 degree but it can rotate like 1.8 degree step motors? How can it be possible?
Camera Wiring - Page 1
Forum section: electronics / beginners

author: Z. Khalid
author_rank: Contributor
timestamp: February 18, 2025, 03:28:15 pm
content: Hi all,I'm just wondering what type of display interface Ford transit reversing camera PZ3T-19G490-DB uses. I need to connect this camera to an LCD for some reason.It has only a mini BNC-like connector which is used for both power supply and video output signal.Please refer to the attached photos.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: February 19, 2025, 03:41:48 am
content: I never looked into that model unit but sending power with video was common in CCTV systems years ago.Check input circuits on Ford unit it feeds to check for capacitor to seperate out video.Jeff

author: darkspr1te
author_rank: Frequent Contributor
timestamp: February 19, 2025, 02:07:01 pm
content: this look similar to Toyota & BMW based camera and that connector is 3 pins, it has signal center, ground then inside the outer housing is power,darkspr1te

author: nali
author_rank: Frequent Contributor
timestamp: February 19, 2025, 02:16:46 pm
content: That looks like a standard FAKRA coaxial connection to me so I'd say combined DC & video signal.

author: u666sa
author_rank: Frequent Contributor
timestamp: February 19, 2025, 07:42:05 pm
content: I say no reason to use that thing. Just get a similar USB camera off ali.

author: inse
author_rank: Super Contributor
timestamp: February 19, 2025, 09:32:24 pm
content: The fakra connector system is derived from SMB coax connector with an additional plastic sleeve for coding and locking.For experiments you can start with commercially available parts.I can hardly imagine a triaxial wiring as for all I know this is obscenely expensive and the cable mounting a science by itself.

author: Z. Khalid
author_rank: Contributor
timestamp: February 20, 2025, 06:57:30 am
content: Quote from: u666sa on February 19, 2025, 07:42:05 pmThis camera is not going to be used for personal purpose.A friend of mine works in a company where they make car spare parts, including this camera's coaxial cable. Some of the cables they produce have low immunity against noise and that causes a bad image. He asked me if I can make something like a test system so that they can verify that every new cable they produce is flawless.I have used industrial cameras (COGNEX- OMRON- SVS-Vistek) but this is the first time a deal with such a camera.

author: inse
author_rank: Super Contributor
timestamp: February 20, 2025, 11:21:48 am
content: Somehow I doubt this was the right approach to an end-of-line quality control.If they use the specified cable, I wonder how variations in immunity were possible.If the connector mounting process is unstable, I would propose resistance measurement.And a review of the mounting procedure.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: February 20, 2025, 02:19:07 pm
content: This is a common problem in automotive aftermarket video and audio equipment with varrios causes.Poor quality cables/wire, ground loops, grounding, sheilding, types of isolation, and others may be the cause.Jeff
Camp fire sparks, an odd question. - Page 1
Forum section: electronics / beginners

author: GadgetBoy
author_rank: Regular Contributor
timestamp: September 01, 2019, 02:34:39 am
content: I'm considering using an aluminum mesh to catch sparks from a camp fire so that they can't hit a tarp and melt holes in it. Do you think they have a positive enough potential to be attracted to a grounded mesh?

author: IanB
author_rank: Super Contributor
timestamp: September 01, 2019, 02:51:45 am
content: Quote from: GadgetBoy on September 01, 2019, 02:34:39 amWhy would you think electrostatics comes into it? And if a mesh is grounded, why positive and not negative? Both would be attracted equally. Charge is charge.Short answer: electricity doesn't come into it. If the sparks (burning embers) are bigger than the holes in the mesh they will be stopped by it. If they are smaller then some may get through.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: September 01, 2019, 03:33:12 am
content: I think they move mostly based on convection and inertia (water vaporizing, wood gas exploding).The best way to avoid this is to only burn dry wood, or dry it before burning... and keep a safe distance from anything inflammable.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 01, 2019, 04:01:50 am
content: 1. Note, a huge bonfire may be so hot that the aluminum screen would have to be quite high up, and quite large, to avoid melting it. A stainless steel screen may be more practical. A modest sized campfire for cooking and warmth should be okay though. (You didn't specify, so, making that clear.)2. There's probably little charge coming off the fire itself, of either polarity. Charcoal is conductive, and flames contain ions (especially the readily ionized sodium, not even so much by quantity as by sheer optical output) thus making the fire somewhat conductive and keeping charge equalized.3. You can still do it, by alternating charged screens. You need multiple screens of course, insulated from each other, and charged with high voltage. Screens are okay for the charging grids, but the precipitators should be flat vanes to reduce the air velocity and turbulence flowing over the stuck particles.It's probably more practical to spray the tarp with water, or spread dirt on it, or just not keep it so close to the fire. Or not place it downwind of the fire, but, there's the old campfire superstition about saying/doing things to make the smoke go away from ones' position that always seems to work never but sorta... Basically, the wind is always changing at ground level, so not much help there.Tim

author: Dundarave
author_rank: Regular Contributor
timestamp: September 01, 2019, 04:25:40 am
content: How about simply applying some tin foil to the exposed areas of the tarp within spark distance?

author: Jwillis
author_rank: Super Contributor
timestamp: September 01, 2019, 07:49:12 am
content: There are screens made for camp fires.Unfortunately they seem unrealistically expensive.But you could build one easy enough just make sure you use steel mesh,Aluminum will most certainly melt as T3sl4co1l mentioned.
camshaft sensor op amp single supply - Page 1
Forum section: electronics / beginners

author: NotANewbie
author_rank: Contributor
timestamp: July 25, 2015, 03:29:53 am
content: I'm trying to convert a reluctance camshaft position sensor output to something usable.It only produces a 46 mv swing, +23mv -23mv.I have no problem with the crankshaft sensor which has a 200mv swing and my digital conversion chip needs a 160mv swing.So I'm thinking I need an op-amp to increase the 20mv to 200mv, a 10x gain.Well I tried this with a lm082 op amp, with a 9k and 1k resistors, so about a 9x gain.But I get no output.And now I think it is because I'm using a single 5v supply on the op amp, and it in fact wants a +5v and -5v minimum,is that my problem? I have +12v available, if I use +12v and gnd, will that do it?

author: Skimask
author_rank: Super Contributor
timestamp: July 25, 2015, 04:22:25 am
content: Virtual ground.

author: mikerj
author_rank: Super Contributor
timestamp: July 25, 2015, 07:51:08 am
content: Quote from: NotANewbie on July 25, 2015, 03:29:53 amReluctance sensors typically produce several volts, the actual amplitude being proportional to frequency (engine speed). 46mV is ludicrously low for a VR sensor, so I'm guessing you aren't measuring the open circuit voltage (i.e. it's connected to the ECU which is loading/clamping the output)?If it's already connected to another circuit, then you will need to deal with any common mode voltage which may be applied to sensor by that circuit.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 25, 2015, 12:38:58 pm
content: Mikerj is rightThe output of typical sensors is in the volts range and I have seen up to 30 Volts, not clampedBut there are also sensors used in the automotive industry that only put out mVHere are 2 examplesThe first one is of a Mercedes engine (26 V Pk/Pk)And the second one of a GM engine, with a big exception 16 mV output Pk/Pk (It is a ridicules design)If your engine computer is expecting a higher voltage, just use a higher output sensor.But there is a good possibility, your sensor is broken.

author: NotANewbie
author_rank: Contributor
timestamp: July 25, 2015, 02:52:46 pm
content: This is the OEM camshaft sensor on a ford taurus v8.I'm measuring it at engine crank speed, open circuit. I'm building my own ECU.It is possible that the voltage ramps up quickly at higher rpm once the engine starts.The good news I don't really need the cam sensor, so the solution is to not use it, problem solved!But I'd still like to know how to setup the op amp. Use 12v and a voltage divider virtual ground for the VCC= ?

author: Derick Freese
author_rank: Contributor
timestamp: July 25, 2015, 06:55:18 pm
content: Got any pictures of your SHO?
Can 1N4937 replace 1N4007 in switching power supply? - Page 1
Forum section: electronics / beginners

author: tpd
author_rank: Contributor
timestamp: January 23, 2024, 04:04:21 pm
content: Hello,Can I replace 1N4007 with 1N4937 in switching power supply (there are 4 of them playing gretz, burnt to the ground by short circuit)?Thanks

author: Kleinstein
author_rank: Super Contributor
timestamp: January 23, 2024, 04:09:57 pm
content: The 1N4937 has only 600 V rating. This can be a bit low when used with more than 200 V mains. In a normal bridge rectifier the diodes would see up to 2 x the peak voltage or about 2.8 times the RMS voltage - so 644 V for 230 V main and excursions to higher mains come on top.The peak current rating also seems to be a bit lower and the forward voltage drop a bit higher, which may be an issue.

author: tpd
author_rank: Contributor
timestamp: January 23, 2024, 04:22:45 pm
content: Quote from: Kleinstein on January 23, 2024, 04:09:57 pmThanks

author: tunk
author_rank: Super Contributor
timestamp: January 23, 2024, 04:49:11 pm
content: Post photos of the PCB (both sides), then someone may be able to see if it's ok.

author: MarkT
author_rank: Frequent Contributor
timestamp: January 24, 2024, 11:22:09 am
content: Quote from: tpd on January 23, 2024, 04:04:21 pmGiven the 1N4007 is a slow rectifier it must simply be the bridge rectifier input, which doesn't see high speed switching - its best not to replace slow recitifers with fast ones as this can lead to much EMI generation. Soft-recovery fast rectifiers are more suitable, but I'd replace 1N4007's with 1N4007's its not like they are hard to source.You might want to investigate whether anything else is burnt out, 4 recitifers don't just fail for no reason - it might be a gross mains surge, but it might be over-current from the succeeding circuitry being shorted out.
Can 220V power transformer be used for 110V application? - Page 1
Forum section: electronics / beginners

author: rvmeush
author_rank: Contributor
timestamp: February 12, 2015, 07:19:36 pm
content: I have a bunch of old transformers laying around, and I need a transformer with a 110 volt primary and a 12 volt secondary. I have a transformer which has a 220 volt primary and a 24 volt secondary. I'm wondering if I can use this 220 volt transformer on a 110 volt main circuit for my application since it should produce about 12 volts output? Is there any problem with using the transformer this way as long as the power requirements of the load don't exceed the transformer VA rating?

author: cjk2
author_rank: Contributor
timestamp: February 12, 2015, 07:24:36 pm
content: Yes, you can do this as long as your don't exceed the current rating of the transformer. Because you have halved the input voltage but the current rating is fixed (by copper losses) you will only achieve half the VA rating of the transformer.Is the frequency the same?

author: retrolefty
author_rank: Super Contributor
timestamp: February 12, 2015, 07:24:47 pm
content: Quote from: rvmeush on February 12, 2015, 07:19:36 pmTrying to operate the transformer at the same maximum VA rating with half the primary voltage would require twice the current draw on the primary winding, the primary wire size being used may not be able to safely handle the increased current. Running the transformer at 110 Vac but at max of half it's max VA rating should be fine.

author: katzohki
author_rank: Frequent Contributor
timestamp: February 12, 2015, 07:25:29 pm
content: See if it has multiple taps. You might be able to reconfigure it for your application. Otherwise, it sounds like your idea will work, but like you said pay attention to the VA rating.

author: Zero999
author_rank: Super Contributor
timestamp: February 13, 2015, 08:58:20 am
content: Quote from: katzohki on February 12, 2015, 07:25:29 pmRead the previous responses: it's the current rating which is important, not the VA rating which will be halved.
Can 3.3V be obtained from 3.7V with LM1117? - Page 1
Forum section: electronics / beginners

author: merymery
author_rank: Contributor
timestamp: June 04, 2021, 07:29:42 am
content: When I look at the LM1117 Datasheet, it says 4.75V<Vin<10V is required to get 3.3V. My circuit supply is 3.7V, is there a way to get 3.3V from 3.7V with the LM1117?

author: wraper
author_rank: Unknown
timestamp: June 04, 2021, 07:32:44 am
content: Do you really have 3.7V or it's a lithium battery?

author: tszaboo
author_rank: Super Contributor
timestamp: June 04, 2021, 08:15:07 am
content: The typical dropout voltage is 1.1V at 100mA. Its just not a good choice for battery powered circuits.

author: merymery
author_rank: Contributor
timestamp: June 04, 2021, 08:41:50 am
content: I actually have the 3.7V supply from the power supply

author: xavier60
author_rank: Super Contributor
timestamp: June 04, 2021, 11:31:46 am
content: It can be done with a TL431 controlling an N-ch MOSFET. A pullup resistor is needed for the Gate to some higher voltage source like 12V.

author: tunk
author_rank: Super Contributor
timestamp: June 04, 2021, 11:39:46 am
content: I guess it depends on how accurate the 3.3V needs to be - maybe you could find a diode (or diodes) with a ~0.4V drop.

author: Zero999
author_rank: Super Contributor
timestamp: June 04, 2021, 11:41:27 am
content: A zener diode will drop around 400mV, but it will depend on the temperature and low. At very low currents, it will hardly drop and voltage and a much higher currents it'll drop move than 400mV.What's the acceptable voltage range of the device you're powering and how much current does it draw?The TPS784 will work with 3.7V in and 3.3V out, at currents of up to 300mA.https://www.ti.com/product/TPS784
can a 6BG6C handle 700volts on grid2? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: January 28, 2020, 01:42:40 pm
content: the datasheet says that it can hold 700 volts on the anode and I want to use all of it but I am gonna put a "triode" switch which connects grid 2 to the anode. but it says that it can only hold 350 volts max on grid 2.so does this mean I can only power it with ~350v if I want to have my "triode" switch?

author: Gyro
author_rank: Super Contributor
timestamp: January 28, 2020, 02:05:44 pm
content: You can normally safely put much more voltage (often anode voltage) on G2 when a tube is wired in triode configuration, in general anyway. The close anode voltage minimises the dissipation of G2 - the anode collects most of the electrons and takes most of the dissipation.The problem comes in pentode or UL mode (your intention I think). This can cause the voltage on G2 to be significantly above the anode voltage during parts of the cycle - that can increase G2 power dissipation a lot (electrons are attracted by G2 preferentially), hence the much lower voltage limit.EDIT: That's the problem with your UL / Triode switch anyway. If you want to know what voltage you can safely put on G2 in Triode mode, connect it to the anode via a milliameter, measure the G2 current and calculate it's dissipation. As long as it's below the limit (3.2W?) you should be fine at that anode voltage. NOTE, also check the pinout - you may risk insulation breakdown if G2 is higher than normal (the Anode is on the top cap, G2 pin is next to a heater pin!)EDIT1: To cut the story short, you ought to be able to use more than 350V in triode mode, but not as high as 700V.
Can a bad ceramic 0603 cap cause massive voltage drop? - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 10, 2025, 05:34:12 am
content: Hi,I'm building this:https://westlicht.github.io/performer/build/ibom.htmlWhen I measure the 100n C8 and R-78E5.0-1.0 (U16) input voltages I'm seeing 2.3v when I should see 12v?I'm obviously not getting 5v at the R-78E5.0-1.0 output.Can a bad ceramic 0603 cap cause massive voltage drop like this?I'm followinghttps://westlicht.github.io/performer/build/and have soldered the power and MCU sections.If C8 is the culprit it's going to be a PITA to remove it, I think I'll have to use two soldering irons.Thanks folks, this forum is the best!

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 10, 2025, 06:12:53 am
content: replaced c8, no change, could a faulty recom cause my issue?

author: chilternview
author_rank: Frequent Contributor
timestamp: May 10, 2025, 06:43:16 am
content: What's supplying the +12v? I'm not familiar with this circuit, but it looks like its got an external +/- 12v supply. Is that working correctly? There appear to be protection diodes on the input, are they the right way round?

author: rthorntn
author_rank: Frequent Contributor
timestamp: May 10, 2025, 07:07:28 am
content: Thanks, diode orientation was the problem.
Can a buck converter provide higher amperage at lower voltages? - Page 1
Forum section: electronics / beginners

author: sofakng
author_rank: Regular Contributor
timestamp: August 10, 2021, 02:40:24 am
content: If I have a power supply that is rated for 15V at a maximum at 3A (ie. 45W) then can I use a buck converter to output a higher amperage at a lower voltage?For example, can I convert 15V (3A max) to 5V but 9 amps? (excluding efficiency losses of course)

author: bobbydazzler
author_rank: Regular Contributor
timestamp: August 10, 2021, 03:08:15 am
content: Yes that's how it works, you'll lose 5-20% through efficiency though.

author: Circlotron
author_rank: Super Contributor
timestamp: August 10, 2021, 05:20:59 am
content: Quote from: sofakng on August 10, 2021, 02:40:24 amYes, but don't forget the converter will pull pulses of ~9A at the input side. That will overload your 3A supply unless you have a good size low ESR capacitor across the converter input.

author: mariush
author_rank: Super Contributor
timestamp: August 10, 2021, 06:46:26 am
content: 15 x 3 = 45w5 x 9 = 45wIt's not gonna work, because you don't have 100% efficiency... at best you're gonna get up to maybe 95-97% efficiency, but closer to 90% efficiency is more realistic.You'll probably want a regulator with a soft start mechanism or something like that so that the converter won't pull a huge amount of current when it starts and like others said, you'll need to have a good input capacitance to buffer the converter's demands.

author: David Hess
author_rank: Super Contributor
timestamp: August 10, 2021, 03:55:50 pm
content: Quote from: Circlotron on August 10, 2021, 05:20:59 amThat is not necessarily the case. A current boosted buck regulator uses a tapped inductor to multiply the current and duty cycle reducing the peak input current. This is easy to demonstrate since the current requirements of the input switch are reduced proportional to the turns ratio of the inductor. TheLT1074 datasheetshows an example of a 5 amp regulator producing a 10 amp output.Just for edification, I calculated the input ripple current as 2 amps for a simple buck converter, and 0.27 amps if a bifilar wound tapped inductor is used, so quite a bit of difference. This would be a good application for polymer aluminum electrolytic capacitors to get a high enough ripple current rating without layout problems.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 10, 2021, 03:58:53 pm
content: Quote from: Circlotron on August 10, 2021, 05:20:59 amIMHO, that proper capacitor should be assumed to be a part of what's called and sold as a "buck converter".But it's a good remark because cheap Ebay crap may fail to provide proper capacitance, causing excessive ripple current seen by the upstream supply and its capacitors, destroyingthemas well. (Crappy supplies normally tend to destroy their own input caps anyway. In the buck converter, input capacitors are stressed the most.)
Can a capacitor connected inline used for ESD protection? - Page 1
Forum section: electronics / beginners

author: Logan
author_rank: Frequent Contributor
timestamp: January 04, 2022, 05:17:32 pm
content: Hi, I want to know if I connect a capacitor between a signal pin and external socket, will that somehow protect the circuit from common (human/cloth) ESD because capacitors are isolated inside? Thanks.

author: jwet
author_rank: Frequent Contributor
timestamp: January 04, 2022, 05:37:59 pm
content: Nope, understand the logic but won't work at all. Fast signals go right through caps without even seeing them. An inductor in series could help, it won't pass an instant pulse, but ideally you'd like a little network with some series impedance, an L or an R or both and a shunt C. This should all be shunted by some kind of ESD clamping diode. If the input isn't high speed, this is pretty easy, at high speeds, you can still do- look at USB port protection schemes. If you can absorb most of the fast nasty stuff in just an LRC network, modern IC pins can usually take 2kV of ESD- they need about this much just to get through tester and packaged up.
can a Fluke amp probe 80i-410 be used with an oscilloscope? - Page 1
Forum section: electronics / beginners

author: Ed ke6bnl
author_rank: Newbie
timestamp: December 22, 2017, 12:19:40 am
content: can a Fluke amp probe 80i-410 be used with an oscilloscope? I am getting a Hantek 6022 usb oscilloscope to play with. I have little to no electronics experience. I have the fluke 80i-410 fluke amp probe already.http://en-us.fluke.com/products/all-accessories/fluke-80i-400.html#resources.I has banana plugs not a bnc connector. If not I will be selling it off for the CC-650 Hantek. I work some on my vehicles and that would be my main use for the tools. thanks ED

author: danadak
author_rank: Super Contributor
timestamp: December 22, 2017, 10:31:30 am
content: Yes if you convert its current output back to voltage. A TIAcan do that, or a resistor. The latter means you have toconsider the following -http://www.tmatlantic.com/how/index.php?ELEMENT_ID=26629http://literature.cdn.keysight.com/litweb/pdf/5992-2656EN.pdfRegards, Dana.

author: Ed ke6bnl
author_rank: Newbie
timestamp: December 22, 2017, 03:16:53 pm
content: thank you for the websites they were helpful to see the types of current measuring devices. the one I have now list on the probe that it puts out 1mv per Amp. can that be inputted into the oscilloscope? in a millivolt scale

author: HighVoltage
author_rank: Super Contributor
timestamp: December 22, 2017, 04:15:08 pm
content: I needed a low cost Transimpedance Amplifier for a similar current probe application and found this cheap one on ebay:https://www.ebay.de/itm/AD8015-Integrated-Transimpedance-Amplifier-Module-Transimpedanzverstarker-Board/162799407957?hash=item25e799d355:g:nxUAAOSwzRlaLz1aI have also plugged the current probe in to a multimeter and hooked up the oscilloscope in parallel.

author: Ed ke6bnl
author_rank: Newbie
timestamp: December 22, 2017, 06:35:14 pm
content: Quote from: HighVoltage on December 22, 2017, 04:15:08 pmcan the fluke with 1mv per amp be hooked up directly to the oscilloscope?how do you use this ebay transimpedance amplifier to measure amps.? it does sayApplications:Fiber Optic Receivers: SONET/SDH, FDDI, Fibre ChannelStable Operation with High Capacitance DetectorsLow Noise PreamplifiersSingle-Ended to Differential ConversionI-to-V Converters
Can a gyrator be used to build a boost converter? - Page 1
Forum section: electronics / beginners

author: dsharp02
author_rank: Contributor
timestamp: March 11, 2016, 01:12:09 pm
content: So I'm reading through TAoE and I get to the section covering active filtering, and it mentions a strange circuit called a gyrator that lets you create an inductive circuit without any inductors. Is the inductive behavior limited to just the frequency response? Or could you use it to build a boost converter?-edit: fixed misspelling, and a missing word

author: bktemp
author_rank: Super Contributor
timestamp: March 11, 2016, 01:18:38 pm
content: It can't be used for a boost converter, because it simulates an inductor. Unlike an inductor a gyrator can not store energy. The energy you put into it gets dissipated as heat, and the energy delivered from the simulated inductor is drawn from the gyrator's power supply. All the signals levels on the simulated inductor are therefore limited by the supply voltage, so it can't generate a higher voltage like a true inductor in a boost converter.
Can a high voltage signal harm a scope because of a wrong setting? - Page 1
Forum section: electronics / beginners

author: mrjazz
author_rank: Newbie
timestamp: June 28, 2013, 09:11:17 am
content: Imagine an oscilloscope can display for instance 40V peak to peak with the highest vertical Volts/div setting. Can I harm the oscilloscope when it is set to the lowest Volts/div setting (for instance 500uV/div) while having this 40Vpp signal fed into it? In other words, do I have to care about the vertical setting before connecting a high voltage source?

author: Unknown
author_rank: Unknown
timestamp: June 28, 2013, 10:24:24 am
content: Depends on the scopes input circuitry really. Without knowing the exact input circuit no one can really say for sure. The chances are it'll be fine though, but don't quote me on that!Does the scope specs not mention anything about maximum input voltage range etc?If in doubt, set your scope probe to x10 to start with, and if your likely to get high spike values leave it at x10.

author: G7PSK
author_rank: Super Contributor
timestamp: June 28, 2013, 10:52:54 am
content: All the scopes that I have seen state the maximum input voltage around the BNC socket. On mine it says 300 Volts PP+DC, This seems to be the voltage level on most scopes or at least all the ones I have looked at, the only time I have seen different was on a USB scope and that was 5 volts only, which is one reason such scopes are useless. I presume that as the maximum Volts/Division on my scope is 5 volts that the 300 volts PP must be the protection level, after all you can use a 10 or a 100 times probe and go to kilovolt probes as well.

author: mrjazz
author_rank: Newbie
timestamp: June 28, 2013, 03:21:21 pm
content: Quote from: Pippy on June 28, 2013, 10:24:24 amIt is a Rigol DS2202.Quote from: G7PSK on June 28, 2013, 10:52:54 amSo you say I only have care about this protection level stated on the front of the scope, but not the current vertical V/div setting?

author: IanB
author_rank: Super Contributor
timestamp: June 28, 2013, 03:29:51 pm
content: Quote from: mrjazz on June 28, 2013, 03:21:21 pmItems of test equipment like scopes ought to be designed with a degree of robustness and tolerance to out of range inputs and operating mishaps. So as long as you don't exceed the specified maximum input voltage you should be OK. You might overload the input amplifiers, but they will just saturate and recover after you remove the overload (but there is no guarantee of signal fidelity under these circumstances).
Can a Higher voltage H Bridge be made to run a Low DC volts Motor - Page 1
Forum section: electronics / beginners

author: jonovid
author_rank: Super Contributor
timestamp: September 29, 2018, 10:52:01 pm
content: my particular problemI have some mini dc motor & gearbox units. the specifications are 1 to 2 volts.the H bridge chip I would like to use is a BA6218 as I have a lot of them.but the BA6218 H bridge is 5 volts.BA6218 datasheethttps://4donline.ihs.com/images/VipMasterIC/IC/ROHM/ROHMS04491/ROHMS04491-1.pdf?hkey=EF798316E3902B6ED9A73243A3159BB0one gearbox unit I would like to use, but it only uses 1.5 volts.if i just add resistance in series with the dc motor and the BA6218 H bridge.so the BA6218 runs at 5 volts. but the dc motor only gets 1.5 volts.currents are less then 100Mma. efficiency will be low ,so will this work?have not seen this particular problem in any H bridge circuit for dc motor control.dc motors are to control mini jack screws in a DIY lens focus assembly.BA6218 H bridge is to be used with TTL 5 volts logic & limit switches - Arduino control.mechanically controlling zoom and a DIY lens focus assembly. is by rotary encodershere is one I have one particular 1990s video-cam lens assembly I would like to use, as all the gears are already in a working assembly. in one unit , just add a new video image sensor to the back. as the bolt hole sizes are standard image sensor pcb mount. see image \/ , this unit came from a 3 volt dc video-cam assembly.

author: oPossum
author_rank: Super Contributor
timestamp: September 29, 2018, 11:57:44 pm
content: Using a resistor will limit torque because the voltage will drop with load on the motor. That may or may not be a problem for this application.A pair of 2.7 V Zeners in series (opposite polarity) instead of the resistor would greatly reduce the low torque problem.

author: rstofer
author_rank: Super Contributor
timestamp: September 30, 2018, 12:58:42 am
content: You're already going to lose 1.2-1.8V internally. That is, given a 5V supply, the most you can expect to see on the output is 3.8V. Look at spec for "Output Saturation Voltage" and note that the spec is for just 200 mA. If the current is higher, the VCEsat will be higher.If you plan to use PWM, just make sure you never go to 100% on. In the case of the 1.5V motor, limit the PWM to 1.5 / (5.0-1.2) or 40%.

author: David Hess
author_rank: Super Contributor
timestamp: September 30, 2018, 03:45:36 am
content: There is a good chance it will operate well enough at a lower supply voltage than listed in the datasheet. The logic inputs will not care. Try it.
Can a RAM (Rechargeable Alkaline Manganese) battery be charged in NiMh charger? - Page 1
Forum section: electronics / beginners

author: abdulbadii
author_rank: Frequent Contributor
timestamp: August 12, 2017, 02:04:27 pm
content: Can a RAM (Rechargeable Alkaline Manganese) battery be charged with NiMh battery charger? If yes how to do it correctly?

author: Audioguru
author_rank: Super Contributor
timestamp: August 12, 2017, 02:16:38 pm
content: Rechargeable alkaline manganese batteries were sold 30 or more years ago and few were sold because they were horrible. Why are you using them today?I use Ni-MH rechargeable batteries and a charger made for them for most portable items and use Li-PO batteries with their chargers for the others.
Can a thermocouple give the temp of a metal surface? - Page 1
Forum section: electronics / beginners

author: Peabody
author_rank: Super Contributor
timestamp: November 17, 2018, 03:01:22 am
content: Or does the fact that it's touching metal mess up the reading? So if I wanted to measure the temperature of a hotplate for reflow purposes, could I use a thermocouple?

author: ogden
author_rank: Super Contributor
timestamp: November 17, 2018, 03:10:18 am
content: Quote from: Peabody on November 17, 2018, 03:01:22 amIndeed. Just make good thermal, not galvanic connection.

author: Teledog
author_rank: Regular Contributor
timestamp: November 17, 2018, 04:48:00 am
content: Quick & dirty: ..I use a non-contact IR/laser thermometerIt's best if you paint the surface flat black first though (hi-temp/ BBQ paint)

author: Wan Huang Luo
author_rank: Regular Contributor
timestamp: November 17, 2018, 05:08:07 am
content: Quote from: Peabody on November 17, 2018, 03:01:22 amyes a thermocouple shouldn’t get messed up by a reflow hot plate so you’re good to go

author: Peabody
author_rank: Super Contributor
timestamp: November 17, 2018, 06:02:13 am
content: I had thought about using an IR thermometer, but my understanding is that it would need to be adjustable as to the emissivity of the surface, and one that would do that would be a lot more expensive than a thermocouple meter (such at the TM-902C).So there appears to be a difference of opinion. One says the contact has to be non-galvanic, but the other says it's ok. Maybe the metal contact would be non-galvanic if no current actually flows. Well I guess high-temp epoxy would make the question moot.

author: Ian.M
author_rank: Super Contributor
timestamp: November 17, 2018, 09:12:19 am
content: If the thermometer is battery powered and not grounded, it doesn't matter if the thermocouple tip makes electrical contact with the hotplate. If however any part of the thermometer circuit is grounded, then you have to consider the effect of contact on its input circuit a lot more carefully, and need detailed knowledge of the input circuit used, which may be an issue if you want to use a non-isolated thermocouple as the sensor for an off-the-shelf controller for the hotplate.

author: Peabody
author_rank: Super Contributor
timestamp: November 17, 2018, 03:03:31 pm
content: Quote from: Ian.M on November 17, 2018, 09:12:19 amIn this case the TM-902C is self-contained and battery powered, so it should be ok. The idea is to control the temperature manually based on the temperature display, so there is no contoller circuit. Of course it remains to be seen whether this will work, but it seems it should with a little practice. It seems most people use an IR thermometer, but it looks like a thermocouple would give more accurate readings.Thanks very much.Thanks very much.