hybridfree/eevblog-posts huggingface dataset:
A substitute of 5mm DIP led in SMD version - Page 1
Forum section: electronics / projects

author: Yaroooo
author_rank: Regular Contributor
timestamp: July 25, 2019, 07:34:40 am
content: Hi guys,I've a problem where I've difficulties to find a solution.A very simply circuit, an aesthetic (and functional) panel is composed by only:- 200 5mm Water Clear - LEDs- 50 resistor- powered by 24v.For a lot of reason, like mechanical, appearance and production, would be good to find an SMD alternative.I found that conversion from Standard LED to SMD LED is difficult.My LEDs have this characteristics:- Between 17k-20k mcd, one color between 8k-10k mcd;- Lens have about 20deg;- 5mA aprox. on single LED.Can't find a suitable, and low cost, SMD LED with same char. Do you have suggestions?

author: DeanA
author_rank: Regular Contributor
timestamp: July 26, 2019, 11:43:19 pm
content: You say,Quote from: Yaroooo on July 25, 2019, 07:34:40 amSo 17-20K mcd which is 17-20 candela, 20deg and one colour 8-10 candela, that is quite bright and quite narrow viewing angle.Most SMT LEDs will have a much larger viewing angle (and hence lower candela) than that. Typically if you require narrow viewing angle for a SMT LED you would need to add secondary optics to reduce the viewing angle and increase on axis luminous intensity.There are SMT LEDs from Avago (oops, now Broadcom)https://docs.broadcom.com/docs/AV02-2372ENthat would give you a 30deg viewing angle and not quite as bright as your 5mm DIP 20deg, have a look at those and see if they will do the job.

author: sleemanj
author_rank: Super Contributor
timestamp: July 27, 2019, 02:03:19 am
content: Quote from: Yaroooo on July 25, 2019, 07:34:40 amWhere did these specifications come from? Are they real specifications in a datasheet made by a reputable company, or are they specifications from a random ebay/aliexpress/amazon seller?

author: DeanA
author_rank: Regular Contributor
timestamp: July 27, 2019, 06:16:38 am
content: Quote from: sleemanj on July 27, 2019, 02:03:19 amYes, I had similar thoughts, those kind of outputs are quite high, you would normally only need something of that kind of intensity and viewing angle for outdoor signage or similar, will wait for more info from the OP.

author: Yaroooo
author_rank: Regular Contributor
timestamp: August 05, 2019, 04:45:07 pm
content: Quote from: DeanA on July 27, 2019, 06:16:38 amThis are for outdoor application. So are exceptionally bright and they has an increased price.I've decided to keep DIP version, we had too much complications and change LED type would have been not commanded.Thanks anyway for answers.
A summary of electronics that everyone can understand - Page 1
Forum section: electronics / projects

author: electroagenda
author_rank: Newbie
timestamp: October 29, 2021, 09:30:04 pm
content: Hi all,It happenned to me that quite often I was enquired by my friends about how things work in electronic devices. I am talking about the typical users of devices that one day want to understand them at a lower level. The things is that their profile is not usually targeted by typical tests. They really want to understand the concepts and fundamentals, but without going to the mathematical and physical details.So I decided to write a summary of electronics for that kind of profile. I share it here and hope it can help or at least be interesting for somebody else:https://electroagenda.com/en/a-summary-of-electronics/

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 30, 2021, 03:22:54 am
content: Please don't have each page open its own tab.

author: electroagenda
author_rank: Newbie
timestamp: October 31, 2021, 09:39:51 pm
content: Yes, more people told me an I think you are right. At least for the links that goes to the previous/next page, they should open in the same tab.Lately I have been a bit lazy to change that issue link by link... but at some point I intend to fix it.Thanks for the feedback.

author: electroagenda
author_rank: Newbie
timestamp: November 10, 2021, 10:24:50 pm
content: Quote from: NiHaoMike on October 30, 2021, 03:22:54 amFixed
A super simple PoE device - Page 1
Forum section: electronics / projects

author: compet17
author_rank: Regular Contributor
timestamp: April 16, 2018, 07:23:51 am
content: Recently I got an used Cisco PoE switch for a function test. Testing the network connections was not difficult but how to test the PoE capabilities?I needed a PoE testload.So I started reading PoE documentation and came up with this solution. I tried it and it works and it probably helps others who are looking for a simple PoE device.Of course in my design there is no data connection, it's only a PoE power device. But the design can be altered and Ethernet transformers can be used instead of the resistors.The function is simple: At first the switch port checks if there is a 25k resistance connected. Then the voltage is increased to sense the device power class. This step is optional and not included with my device. If the power class can not be determined it assumed a class 0 (0,44–12,96 W, widest possible range). Then the voltage goes up to full 48VDC and the load gets connected by the mosfet/zener circuit.PoE can be supplied on two different paths. One can use the not used cable pairs for power or one can use the signal lines and inject DC power into the transformer center connection. That's the reason why I used two bridge rectifiers... one for the first case and one for the other.... so it should work on any type of switch. Rectifiers are recommended because the polarity may not always be the same. Different manufacturers have different solutions and sometimes you encounter a crossed cable installation. :-)

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 16, 2018, 03:17:17 pm
content: I would suggest adding a 1k resistor between the MOSFET gate and the threshold sense circuit, then add a 12V zener from gate to source. As it is, the gate voltage with 48V applied to the circuit is pretty much right at the upper limit of most MOSFETs.

author: compet17
author_rank: Regular Contributor
timestamp: May 15, 2018, 03:21:51 pm
content: Yeah you're right, that may be a good idea... 10k would be even better, less waste current.
A susbstitute for the 7812 Regulator - Page 1
Forum section: electronics / projects

author: VanitarNordic
author_rank: Frequent Contributor
timestamp: October 21, 2018, 11:04:15 pm
content: I am looking for a substitute of the general purpose 7812 which should introduce lower dropout and more stability, load regulations and so on ...No switching, only linear and easy to find

author: oPossum
author_rank: Super Contributor
timestamp: October 21, 2018, 11:10:19 pm
content: LM1117-ADJProper capacitorsmustbe used for stability.http://www.ti.com/lit/ds/symlink/lm1117.pdfAlso made by many other manufacturers.

author: VanitarNordic
author_rank: Frequent Contributor
timestamp: October 21, 2018, 11:29:45 pm
content: Quote from: oPossum on October 21, 2018, 11:10:19 pmThanks, but I'm looking for a fixed output voltage, it is preferable. Besides, for SMD ones, the heatsink is a challenge. The current draw could reach 500mA.

author: DaJMasta
author_rank: Super Contributor
timestamp: October 22, 2018, 12:00:44 am
content: I mean, a variable regulator is a fixed regulator with external feedback resistors, but also the 1117 comes in flavors with integrated feedback resistors to have only the fixed output voltage. Typically denoted as 1117-12 or 1117-3.3 or somesuch. SMD packages also offer heatsinking through their tab through the board, and with lesser thermal transfer you can still stick a heatsink on the package itself. There are options if you are not constrained to a TO-220 footprint.Otherwise, there are both some other variants that could be good choices, and there are many circuit variations of the classic 7812 that give you more CMRR, lower drop out voltage, or are binned for tighter regulation. There was a time when they were somewhat similar, but I think you'll find that a survey of several 7812 marked modern parts will turn up quite a number of differing implementations with different characteristics.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 22, 2018, 12:07:22 am
content: Take a look at the MIC2937A:https://www.microchip.com/wwwproducts/en/MIC2937A
A synchronous rectifier in a 2 pin package - Page 1
Forum section: electronics / projects

author: oPossum
author_rank: Super Contributor
timestamp: November 03, 2019, 09:37:18 am
content: Yet another part that I didn't know existed. A MOSFET and control circuitry in a 2 pin package that looks like an ordinary diode.Info begins at 6:20

author: BravoV
author_rank: Super Contributor
timestamp: November 03, 2019, 10:02:14 am
content: Its been for years, TI has it, called SM74611.

author: Twoflower
author_rank: Frequent Contributor
timestamp: November 03, 2019, 10:38:01 am
content: The TI device has a different mode of operation and is not suitable for an SMPS as it is designed as bypass diode. Still the idea to use a voltage pump to every now and then charge an internal cap is nice.But yes, the basic idea to use a MOSFET as switch is similar.
A text user interface (TUI) for Rigol DS1054Z - Page 1
Forum section: electronics / projects

author: amosborne
author_rank: Contributor
timestamp: August 01, 2022, 02:58:57 pm
content: Picture and GIF attached below.This kind of project has been done a million times, but I've never found the kind of flat user interface that I like. I took it as an opportunity to make a retro-style TUI that lives entirely inside the terminal.The killer feature is when you capture and save the oscilloscope's display, an image of the TUI is also saved. Never forget your obscure scope settings again!The software package is installed via pip (Python). A simple command line tool and a compact Python interface library are also included.Not yet published-- more to come.

author: amosborne
author_rank: Contributor
timestamp: August 01, 2022, 03:01:46 pm
content: I guess GIFs don't play on the forum... you can see it in action on the README (work-in-progress):https://github.com/amosborne/rigol-ds1000z/tree/tui

author: cellularmitosis
author_rank: Unknown
timestamp: August 01, 2022, 08:48:17 pm
content: This is amazing! Thanks so much for publishing on GitHub

author: amosborne
author_rank: Contributor
timestamp: August 02, 2022, 01:13:47 am
content: Thanks! I'll update this post when I release it in a few days.

author: amosborne
author_rank: Contributor
timestamp: August 11, 2022, 02:29:06 pm
content: Hello all-- I've published this project so that others may download and use it as they wish.See an action video here:https://github.com/amosborne/rigol-ds1000zAvailable for download here:https://pypi.org/project/rigol-ds1000z/A short blog post I wrote about it here:https://www.osborneee.com/rigol-ds1000z/Let me know if you like (or not)!

author: cellularmitosis
author_rank: Unknown
timestamp: August 11, 2022, 05:12:39 pm
content: Thanks so much for taking the time to document and publish this project!

author: m98
author_rank: Frequent Contributor
timestamp: August 15, 2022, 09:27:33 am
content: Nice work. Also never knew you could have mouse interaction on a TUI

author: Robotec
author_rank: Contributor
timestamp: August 15, 2022, 11:36:24 am
content: I see the python control library extremely useful for test setups, thank you.
A to D converter for anti lock braking wheel speed sensors - Page 1
Forum section: electronics / projects

author: Chris Wilson
author_rank: Super Contributor
timestamp: April 12, 2016, 09:20:34 am
content: I am running out of small Siemens made analogue to digital converters for converting the sine wave of magnetic anti lock automotive braking wheel speed sensors to a square wave digital signal. They no longer make these and I am looking at building a small batch. I use them when changing to a programmable after market ECU in performance road cars and race cars, s most of these ECU's expect a digital signal inputting.Can anyone give simple suggestions for building something, ideally four channel in one package? Here's a link to one of the Siemens devices I looked at with a scope:http://www.mkivsupra.net/vbb/showthread.php?316889-Traction-Control-and-ABS-analogue-to-digital-converters&highlight=analogue+digitalThanks!

author: mongo
author_rank: Contributor
timestamp: April 12, 2016, 04:04:23 pm
content: I would hate to make a mistake in this project but is there any reason a simple Schmitt trigger wouldn't fit your needs?It would seem that a ADC would be overkill when really what you need is the comparator function.

author: retrolefty
author_rank: Super Contributor
timestamp: April 12, 2016, 04:45:21 pm
content: Quote from: mongo on April 12, 2016, 04:04:23 pmThis is correct.

author: max_torque
author_rank: Super Contributor
timestamp: April 12, 2016, 06:14:48 pm
content: Early (Pre ~2003) vehicles used VR sensors, that output a sine wave whose amplitude is proportional to the tooth passing velocity. To read these, you need to use pretty much any VR amplifer IC that has a large input impedance (as most do). Most of those IC,s low pass filter the input to get an average signal then look for zero crossing to create the digital edges. Google for "VR sensor amplifier" or "VR Sensor conditioner" etc(modern cars use 7-14mA current digital sensors that also encode diagnostic and rotational direction information)

author: Andreas
author_rank: Super Contributor
timestamp: April 12, 2016, 06:31:37 pm
content: Yes that is the point.you need a adaptive trigger level + hysteresis.the sensor voltage changes between several 100 mV and up to 100V for the speed range 1 MPH to 150 MPH with different tolerances of air gap.ICs (single channel) are e.g. LM1815 or CY30with best regardsAndreas

author: langwadt
author_rank: Super Contributor
timestamp: April 12, 2016, 06:40:18 pm
content: Quote from: Chris Wilson on April 12, 2016, 09:20:34 amone config I've seen work well with everything from cranks sensors to abs sensor is based on a 74hct14one inverter is used to make an oscillator, the output of that is lowpass filtered and used to bias the rest ofthe inverters each via a large resistor, input signal is capacitive coupled and the inverter inputs have a seriesresistor to limit current with high input voltages
A tool to show of your PCB module - Page 1
Forum section: electronics / projects

author: zofz
author_rank: Regular Contributor
timestamp: March 11, 2019, 10:11:53 pm
content: I have made some changes to the ZofzPCB mesh file format, hoping to create a kind of browser extension, a something like pdf format is.See the example at:https://www.zofzpcb.com/ViewOnly.html#exampleif this is of any interest, I will provide free licenses to the OSH designers.

author: zofz
author_rank: Regular Contributor
timestamp: March 12, 2019, 06:36:03 am
content: Here is how the program shows it. Mechanical measurements, component browsing.
A transmitter and receiver for a signal output - Page 1
Forum section: electronics / projects

author: Chriscrowdercakes
author_rank: Newbie
timestamp: April 04, 2016, 12:36:48 am
content: Hi guys,I'm looking to mount something in a vehicle that basically when the vehicle gets within a certain distance I can then send a signal from the unit that picked up the vehicle is close. Any ideas what sort of transmitter receiver units or even type I should be looking at. Thanks guys much love xxx

author: Chriscrowdercakes
author_rank: Newbie
timestamp: April 04, 2016, 12:38:10 am
content: Sorry can I add the distance I need is say 20 metres xx

author: moffy
author_rank: Super Contributor
timestamp: April 04, 2016, 01:52:23 am
content: What about ETAG type systems?
A universal (sorta kinda) test oscillator question - Page 1
Forum section: electronics / projects

author: Achu
author_rank: Contributor
timestamp: October 19, 2020, 05:04:47 pm
content: Hi,I would like to know if there is any particular LC oscillator topologies which can be used to test a wide range of LC combinations. Since I don't have a scope, I would use an rf probe to view the output level on my DMM.Any help guys?Thank you.

author: bob91343
author_rank: Super Contributor
timestamp: October 19, 2020, 06:27:11 pm
content: Here is a place to exercise your creativity. If you want to measure a resonant circuit, apply a sweep generator and see how the output changes. Use a very slow sweep so your voltmeter can follow.Better yet, get an oscilloscope. They can be very cheap or free, depending. Working on electronics without one is like listening to music with earplugs or like looking for a stray cat at night.

author: niconiconi
author_rank: Frequent Contributor
timestamp: October 19, 2020, 08:09:22 pm
content: Quote from: bob91343 on October 19, 2020, 06:27:11 pmLocating cats at night is easy, their eyes glow in the dark.

author: drvtech
author_rank: Regular Contributor
timestamp: October 19, 2020, 08:19:20 pm
content: Sounds like a grid dip oscillator is what you're looking for.

author: ledtester
author_rank: Super Contributor
timestamp: October 19, 2020, 11:51:22 pm
content: The AADE LC Meter incorporates a circuit that oscillates a LC tank at its resonant frequency.I've attached the schematic and you can find comments about it here:https://sites.google.com/site/vk3bhr/home/lcm1I also ran across a Russian design which used transistors - I'll see if I can dig it up.
A USB Meter's Output reads a LIVE 12 Volt output and DOES NOT BLOW UP? - Page 1
Forum section: electronics / projects

author: Zero_Ego
author_rank: Regular Contributor
timestamp: May 15, 2025, 09:53:31 am
content: Hi,I saw this USB Tester on youtube (Link w/time stamp below)The video shows someone pluging 12volts (male DC5.5 barrel jack) directly into the OUPUT of this USB multimeter. Yes you read that correctly - he plugged a 12volt OUTPUT (male) into the OUTPUT of this USB mutimeter - 12volts and no smoke?He knows its wrong and lets out a warning first. Clearly he has already rolled the dice with this with a quick warning,"Watch this!" he says, and I did think it was going to smoke like a Cuban cigar but nope!Check it out as it's time stamped.https://youtu.be/CEPRTR4ToI8?si=uhdCrXaS3KhmXZvl&t=140Anyone know what is at the heart of the these units and how do they have bi-directional communication without blowing up with 12Volts blasted into what is clearly labelled an Input?ThanksZEApologies I posted this twice once in the beginners room. Please remove is problematic.

author: kripton2035
author_rank: Super Contributor
timestamp: May 15, 2025, 10:24:05 am
content: the tester has usb-c plugs, and with usb-c you can go up to 20V, so it has been build for this voltagean older usb-a tester would surely blow up at 12v (or be protected for it)

author: voltsandjolts
author_rank: Unknown
timestamp: May 15, 2025, 10:27:20 am
content: Please do not double post. Your previous thread is here:https://www.eevblog.com/forum/beginners/when-the-output-is-also-the-input-but-is-the-input-also-the-output/

author: Berni
author_rank: Super Contributor
timestamp: May 15, 2025, 10:29:07 am
content: USB-C ports go up to 20V (or even 48V under the new standard) so these testers are designed for this.It is not hard to do, they likely need a 3.3V regulator to power the MCU and screen, so they just need to use a LDO that has up to 30V input.For communication the CC pins on the USB-C connector are used and those carry a low voltage digital/analog protocol to identify what the port is supposed to be doing. This is all by the USB-PD standard.
A variable fan speed control that I reversed eng... - Page 1
Forum section: electronics / projects

author: AlanR
author_rank: Regular Contributor
timestamp: December 28, 2013, 12:24:44 pm
content: I'd figure I would share with everyone this unique fan speed controller circuit that I reversed engineered out of PC Power & Cooling computer power supplies. It requires a bit of DC circuit theorem understanding if you want to know why it works the way it does with its delay ramp of the fan under varying temperatures. It is designed to work at 12 volts and can support DC fans that require up to 500 milliamps of current.
A Variable Low Drop out low noise Linear post Regulator - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: October 22, 2017, 01:19:24 pm
content: Hi,I have designed this Circuit, I wanted to be able to adjust the Voltage and Current in the output of my DIY power supply. I wanted it to be Low noise, (under 500uA and 500uV) and be able to adjust the Output voltage and current, But It seems that my circuit would dissipate about 3V across it and it's a ton, in what ways Can I improve it's performance? any idea's and hints are welcomedAlso I want to figure out a way to adjust the output with a DAC from my MCU

author: Zero999
author_rank: Super Contributor
timestamp: October 22, 2017, 01:47:21 pm
content: The LT3081 will do this and can be connected in parallel, if more current than 1.5A is required.http://cds.linear.com/docs/en/datasheet/3081fc.pdfTo get down to 0V a minimum load current is required, which can be achieved by adding a current mirror to the output. R1 needs to pass more than 4mA. Tr2 will also pass approximately 4mA down to fairly close to 0V.

author: dmills
author_rank: Super Contributor
timestamp: October 22, 2017, 03:38:49 pm
content: IIRC Linear published a complete bench supply around that basic idea ("Linear applications journal"?).Regards, Dan.

author: iainwhite
author_rank: Unknown
timestamp: October 22, 2017, 04:25:29 pm
content: LT journal power supply article:http://www.linear.com/docs/45095

author: macboy
author_rank: Super Contributor
timestamp: October 23, 2017, 03:42:44 pm
content: That 10k resistor feeding current into the BD681... if you can connect it to a voltage higher than Vin, then you can reduce the dropout voltage significantly.The current limit is very basic, and it necessarily results in a minimum of 0.6 V of dropout. You will need an amplifier to do better.I'd move the current shunt and limiter to the input side of the pass transistors. Connect the 10k resistor mentioned earlier to Vin (not the output of the current shunt). Then you reduce the dropout a little bit. Refer to my circuit below that I designed a few years ago and is very similar to yours. In my circuit, the extra gain from using two transistors in the current limiter makes it much more accurate/stable than a 1-transistor version. (R3 and R6 are a 1k pot)

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: October 24, 2017, 06:22:46 am
content: Thanks all for your hints, specially macboy

author: BU508A
author_rank: Super Contributor
timestamp: October 24, 2017, 10:12:51 am
content: Quote from: iainwhite on October 22, 2017, 04:25:29 pmI think, the bridge rectifier in Fig. 11 is a bit wrong.
A variable stereo blend circuit? - Page 1
Forum section: electronics / projects

author: cvanc
author_rank: Frequent Contributor
timestamp: March 12, 2020, 02:58:29 pm
content: Hi all-I have an interesting problem with recent changes to my home system. Some recordings actually seemtoostereo. I think a variable stereo separation control would be very useful.I would like a continuously variable knob that goes between full stereo & full mono. This control was common on old preamps, FWIW. A good example is the Apt Holman which is highly regarded; photo attached.I'd like to build one passively if possible. It'll probably be lossy but my preamp has a ton of output and can afford to spare some dBs.So... how do I make apassivevariable separation control?

author: jiarui
author_rank: Contributor
timestamp: March 12, 2020, 03:11:50 pm
content: Just buy a small mixer. You only need two channels. Plug the left and right into the two channels. You can then just use the pan control to do what you need.

author: Zero999
author_rank: Super Contributor
timestamp: March 12, 2020, 03:42:47 pm
content: This is the simplest I could come up with. R2 will need to have an exponential curve, as it will have little effect towards the high end of its setting. A taper potentiometer could be used, but it'll have to be wired backwards.
A video for those interested in nixie tubes - Page 1
Forum section: electronics / projects

author: nexus
author_rank: Regular Contributor
timestamp: December 24, 2021, 08:06:54 am
content: Hi all,Just wanted to share a video I made for anyone interested in the topic of nixie tubes.I was drawn towards the discipline of electrical engineering when I first discovered nixie tubes and wanted to make circuits with them. This inspired me to learn a lot about other electrical subjects and made learning fun with an awesome neon glow.After years of collecting tubes and building nixie related projects, I felt that a lot of info regarding nixies was stratified in different and sometimes obscure places. The aim of this video is to shed light on the topic of nixie tubes by putting together pieces of info related to nixie tube history, how nixies work, different kinds of nixies, and how you can get nixies today.Even if you aren't an engineer and are just wondering what the heck a nixie tube is, I might be able to answer that for you!Enjoy!

author: rpiloverbd
author_rank: Regular Contributor
timestamp: December 24, 2021, 02:42:34 pm
content: Thanks a lot. Really informative video. Do you have any tutorial regarding how we can control these tubes with Arduino?

author: nexus
author_rank: Regular Contributor
timestamp: December 26, 2021, 10:04:13 pm
content: Thank you!I do not have a video on that subject (yet), but there are some good ones already on youtube. Check this out:

author: rpiloverbd
author_rank: Regular Contributor
timestamp: December 29, 2021, 10:23:52 am
content: Oh! Thanks a lot.
tube compressor circuit, ideas for voltage adjustable amplifier/gain circuit - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: July 30, 2022, 04:28:47 pm
content: I have a pair of signals that are 180 degrees out of phase with each other, and I have a set DC voltage on them, I need a way to offset the voltage, and I need a way to vary it.at first I thought of a Vbe multiplier but that doesn't seem quite the best solution.the circuit is this:[ Attachment Invalid Or Does Not Exist ]see I was also thinking of offsetting both supply rails of the "ratio" adjustment, but that seems overly complex, and wouldn't be a great design either.the 220k resistors need to be supplied with around 90V and the 47k 0V, and I would want to be able to adjust them to be ~90V for the 47k resistors and 180V for the 220k.90V is an arbitrary value, I just used that because it would be enough adjustment for my design and it's the average voltage the the neon indicators regulate at.it would suffice even with around 60V, and consequently would need only around 60V adjustment.and as to why I'm using a tube diode? for fun

author: mawyatt
author_rank: Super Contributor
timestamp: July 30, 2022, 05:34:02 pm
content: Why not use an op-amp in an inverting configuration with a Signal input and DC Bias input. The ratio of the feedback resistor and Signal input resistor determines Signal gain, and the ratio of same feedback resistor and DC Bias input resistor determines Offset Gain.The output is - Vin*Signal Gain +- DC Bias*Bias Gain, and if DC Bias*Bias Gain equals negative of the DC component of Vin*Signal Gain the net result is the Input AC waveform content with DC portion removed without affecting the AC content other than by -Signal Gain (assuming within BW and voltage range of said op-amp).Best,

author: jonpaul
author_rank: Super Contributor
timestamp: September 19, 2022, 06:45:11 am
content: see the classic 1950s..1960 valve compressor circuits eg RCA tube manual, and broadcast compressorsJ

author: JohnnyP
author_rank: Regular Contributor
timestamp: September 20, 2022, 07:11:06 am
content: LM13600 is the one you are thinking ofLM13700https://www.ti.com/lit/ds/symlink/lm13700.pdf
A2135-H Maestro GPS module - Page 1
Forum section: electronics / projects

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: November 03, 2015, 10:18:26 pm
content: Hi All,Does anybody has experience with the A2135-H Maestro GPS module ?http://eu.mouser.com/ProductDetail/Maestro-Wireless-Solutions/A2135-H/?qs=sGAEpiMZZMuw1rG4%252bG7fpkLWxYqA2S96F69tvrI4uD0%3dThanks
A92 B331 Transistor - What Alternative Can I Buy? - Page 1
Forum section: electronics / projects

author: FazzaGBR
author_rank: Newbie
timestamp: November 20, 2024, 02:44:03 pm
content: I've got a 400W amplifier with some A92 B331 tranistors that are shorted and I need to buy some replacements but the A92 B331 transistors seem to be rare so I'm assuming old and have been replaced with something else but I'm not an expert when it comes to transistors so can anyone recommend a suitable replacement?I normally buy components from RS Components and cpc.farnell.com and neither have the A92 B331 listed - I can only see some on eBay.

author: edavid
author_rank: Super Contributor
timestamp: November 20, 2024, 03:36:33 pm
content: If they are in a TO92 case, they are MPSA92 transistors. The B331 is not part of the part number.

author: Benta
author_rank: Super Contributor
timestamp: November 20, 2024, 04:54:37 pm
content: Yep, Motorola MPSA92, today onsemi. Should be still available.
About Aviosys IP Power 9258 firmware - Page 1
Forum section: electronics / projects

author: mrcico
author_rank: Newbie
timestamp: September 24, 2024, 12:51:18 pm
content: Hi,I have few ip power 9258 (ethernet edt.) and want to update firmwares up-to-date. I found few firmwares but all of them back in 2015 and web interfaces ugly as duck.Seems aviosys updating firmwares time to time but not available for download. I appreciate if anybody have a copy or dump of latest firmware of aviosys ip9258?
About flux - Page 1
Forum section: electronics / projects

author: han
author_rank: Frequent Contributor
timestamp: March 30, 2014, 02:52:38 pm
content: How actually Flux clean solder joint?If the flux is mildly acid, can it eat away the metal?and why is it not make corrosion worse?Any chemical expert here?

author: IanB
author_rank: Super Contributor
timestamp: March 30, 2014, 02:58:19 pm
content: When flux is heated up to soldering temperature it dissolves the surface oxide layer on the metal so that the molten solder can get to the clean metal underneath.Yes the flux can eat away the metal, but when acid dissolves metal it leaves a clean metal surface behind so this is not a problem during soldering.However, some fluxes are quite corrosive and must be cleaned off thoroughly after soldering. If flux residues are left behind they may corrode the joints badly over the following months.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 30, 2014, 02:59:08 pm
content: Yes, loosening and dissolving surface oxides.The acid is a very mild organic type, so it corrodes pure metal very slowly. Very old solder joints (antique 50+ years old) may have extra gray, white or green deposits. Solid rosin is not very corrosive because it is frozen and can't react, and forms a layer which blocks oxygen. Water will accelerate the process, as always.Tim

author: han
author_rank: Frequent Contributor
timestamp: March 30, 2014, 03:02:56 pm
content: What happen when Flux / Solder Paste with flux expired?is the flux decompose, or just loose the solvent?

author: rdl
author_rank: Super Contributor
timestamp: March 30, 2014, 03:44:41 pm
content: It could decompose or oxidize over time, or it could be a slow loss of volatile components, or it could be something else. Manufacturers of chemical products can not guarantee the stuff they make will work forever, so they apply an "expiration date". This normally covers a period of time that they arecertainit will still work properly. In most cases the material will still continue to work correctly long after it has "expired".

author: mariush
author_rank: Super Contributor
timestamp: March 30, 2014, 04:07:50 pm
content: If you didn't see this already, please watch it:This is first part of a series of videos made by Pace. The videos seem a bit outdated but the information and explanations are still valid, so you'll learn a lot from them.
About GSM Chip/Ceramic Antenna - Page 1
Forum section: electronics / projects

author: rneraslan
author_rank: Contributor
timestamp: August 09, 2017, 08:40:56 pm
content: Hello,Recently, I am developing a project that uses Quectel M66 Gsm Module. But so far, I always use the prepared PCB antenna with Ipex connector.which is ->It works fine but I want to use a chip antenna to protect the integrity of the PCB. Here are my questions1- GSM Module says it's frequencies are 850/ 900/ 1800/ 1900 MHz. As I remember It works on 900mhz. So how should I choose proper gsm antenna in the market?2- Is there any gsm antenna suggestion for battery powered quectel m66thank you.

author: helius
author_rank: Super Contributor
timestamp: August 10, 2017, 03:10:53 am
content: Seehttps://en.wikipedia.org/wiki/GSM_frequency_bandsIn Europe and Turkey, 900 and 1800 MHz are used by GSM networks. The other bands are used in the Americas only.If your networks operate in the 900 MHz band, you do not need an antenna for 1800 MHz.

author: stmdude
author_rank: Frequent Contributor
timestamp: August 10, 2017, 06:35:09 am
content: I've been using the Antenova SMD antennas, and they work pretty well for an antenna mounted directly on the PCB.There's quite a bit of requirements on your PCB design in their datasheet, but it's definitely doable.
About multiple interrupt ISR (PIC) - Page 1
Forum section: electronics / projects

author: danielks
author_rank: Contributor
timestamp: October 24, 2011, 04:49:53 pm
content: Can anyone teach me how to write the coding for Interrupt polling type in Hi-tech C ?For example Timer Interrupt and CCP interrupt together...

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 24, 2011, 08:12:42 pm
content: loop:if (PIR1) doMe();if (PIR1) doYou();goto loop;something like that?

author: danielks
author_rank: Contributor
timestamp: October 25, 2011, 05:01:31 am
content: Now I have a coding which consist of 5 interrupts in the ISR. But i only try with 1 timer interrupt and 1 CCP interrupt. I set the timer interrupt priority to high and CCP to low but when ever CCP interrupt happen, the program hang. if I set more than 1 CCP interrupt non of the interrupt will works and program Hang.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 25, 2011, 01:41:35 pm
content: your code pls? ... this topic should be moved to microcontroller section.

author: danielks
author_rank: Contributor
timestamp: October 25, 2011, 02:25:36 pm
content: sorry about that..my coding..void interrupt ISR(){if(TMR0IE==1&&TMR0IF==1){t++; //increase counter by 1if(t<s1){motor1=1;}if(t<s2){motor2=1;}if(t<s3){motor3=1;}if(t<s4){motor4=1;}if(t==s1){motor1=0;}if(t==s2){motor2=0;}if(t==s3){motor3=0;}if(t==s4){motor4=0;}if(t==1000) //Reset counter to 0{t=0;}TMR0IF=0; //Reset interrupt flag to 0TMR0=250;}if (CCP4IE==1&&CCP4IF==1){count1++;CCP4IF=0;if (count1==1){t1=TMR1;count1==1;CCP4CON=0b00000100; //falling edge detection}if (count1==2){t2=TMR1;count1=0;CCP4CON=0b00000101; //rising edge detection}TMR1=0;}if(CCP5IE==1 && CCP5IF==1){count++;CCP5IF=0;if (count==1){t11=TMR1;count==1;CCP5CON=0b00000100; //falling edge detection}if (count==2){t22=TMR1;count=0;CCP5CON=0b00000101; //rising edge detection}TMR1=0;}}With the CCP5 interrupt in the coding just wont run. it hangs.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 25, 2011, 06:14:12 pm
content: first you put ambiguity to the compiler... CCP5IE==1 && CCP5IF==1 could be...Code:((CCP5IE==1) && CCP5IF)==1(CCP5IE==(1 && CCP5IF))==1CCP5IE==((1 && CCP5IF)==1)this semantics ambiguity is very hard to acertain. maybe there's operator's presedence that make it right, but its safer practice to clearly state what you want, ie i think it should be... if ((CCP5IE==1) && (CCP5IF==1)), note the bracketting.second... whats this? 4th line (arrowed)? i cannot compile that. i dont think thats necessary.Code:if (count==1){t11=TMR1;count==1; // <---------------- ????????????CCP5CON=0b00000100; //falling edge detection}i cannot trace the hanging procedure, try clearing up your code as stated above and see if its working.
About the Starter Battery Lithium Battery Management Board - Page 1
Forum section: electronics / projects

author: daisizhou
author_rank: Super Contributor
timestamp: December 26, 2024, 05:59:11 am
content: Traditional starting batteries use lead-acid batteries, usually with a voltage of 12-14 volts.I see many people using lithium batteries as starting power sources to replace lead-acid batteries.But their production is not standardized, and some people even directly use lithium iron phosphate batteries.But most people use ternary lithium batteries and add a cheap control board for battery management.All of the above solutions ignore a serious problem,That is, when the lithium battery is fully charged, the management board chooses to disconnect the lithium battery,At this time, the voltage will be too high, thus burning out the electrical appliances in the car.I would like to know if there is a professional lithium battery solution specifically for starting lithium batteries?

author: Vovk_Z
author_rank: Super Contributor
timestamp: December 26, 2024, 08:20:14 am
content: BMS doesn't switch off a battery when it is fully charged. It does it when it is close to overcharge.The larger problem for Lifepo4 battery is that it can't work in low temperatures (0 C and lower) so it must be temperature conrolled and heated.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 26, 2024, 12:29:15 pm
content: Quote from: Vovk_Z on December 26, 2024, 08:20:14 amWell, at least won't work with the stock alternator.Really the problem with retrofit LFP starter battery is that the car already has a charger circuitry (insidethe alternator) which is designed for lead acid. So it will use lead acid temperature-voltage compensation curve, outputting higher voltage in cold temperatures, leading to overcharge. (There is this misconception that alternator outputs 13.8V or 14.4V or any other magical made-up number with three decimal places to sound convincing. In reality, alternators measure ambient temperature and output anything from 13.5V to 16V or so. And 16V is 4V per cell for 4s LFP battery, a serious overcharge!)Instead, you would want to have reduced charging current at low temperatures, that way there would be no need to heat the battery; li-ion cells can be charged below 0degC, just with reduced current.Technically, decent li-ion charging logic would be pretty easy to do, but the issue is that the existing control logic is inside the alternator and thus very difficult to replace. A separate DC/DC conversion module would be added but that would be ridiculously expensive and large piece of power electronics. All that isreallyneeded is access to the alternator's field winding (and BMS to controlthatto limit charging current), but unfortunately that does not exist since alternators are completely integrated devices.I don't think this problem is worth overthinking. The best course of action is keep using lead acid batteries for cars designed for lead acid batteries. Proper replacement is a huge engineering task and gains very little.
Abracon Datasheet help - How does the standby pin work? - Page 1
Forum section: electronics / projects

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: December 21, 2017, 01:02:04 am
content: Hi, I am looking at the ASE series Abracon oscillators.http://www.abracon.com/Oscillators/ASEseries.pdfPin 1 says "Tri-State (STBY)" but does not describe the three states? I presume high/low and hi-z but they don't say what is on/standby.Does anyone have an idea. I have looked through as much of the supplemental documentation on their web site as I can and am just not finding it.Thanks

author: floobydust
author_rank: Super Contributor
timestamp: December 21, 2017, 05:24:50 am
content: The output gate has a tri-state ability, the control pin is better called output enable OE and it also has a pullup resistor.So "stand-by"=0V the pin is hi-Z and otherwise (floating or 3.3V) the output gate is enabled and driving the output.Two possible ways to make implement crystal oscillator module "stand-by"; one partially lowers current drain and another compromises start-up time for very low current drain.http://www.taitien.com/wp-content/uploads/2015/12/AP20100105-Tri-State-Function-in-Crystal-Oscillators.pdfAbracon is pretty good with technical questions, if you are still unclear just ask them.

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: December 21, 2017, 05:56:18 am
content: Yes I should just ask them. Just thought I was missing something obvious. It really bugs me they could not find the room on the datasheet to describe it though, I never like to assume it's 'an industry standard' or anything like that.
ABS construction techniques used in making the VERSA-OHM fan box - Page 1
Forum section: electronics / projects

author: robrenz
author_rank: Super Contributor
timestamp: March 19, 2015, 04:56:30 pm
content: This video covers how I designed and built the cooling fan box for the Versa-Ohm decade resistance box. Hopefully you will find something useful or interesting.

author: dr.diesel
author_rank: Super Contributor
timestamp: March 19, 2015, 10:21:09 pm
content: I wonder why my boxes never look that good?Well done Sir.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: March 19, 2015, 11:05:10 pm
content: Nice work. Wish I could do the same.Questions.How do you set the dowels to lock the angular pieces in the right position? In other words how are the dowel holes in the right position for each piece? The plate with the dowel holes is just a grid.Roughly what sort of absolute tolerance do you get out of the machining, is it the same as the the guillotine? I think you said 1 or two thou after the guillotine.

author: robrenz
author_rank: Super Contributor
timestamp: March 20, 2015, 01:27:36 pm
content: Quote from: HackedFridgeMagnet on March 19, 2015, 11:05:10 pmYou will notice on all the angled pieces at least one edge was either vertical or horizontal. That edge got the 2 dowels to form one datum and the single dowel formed the other datum. I just set my program origin after that to make sure I had material to remove on all the edges.The parts are probably within .002" of programmed dimensions but it really is not that critical on this application. I didn't even measure the parts off the mill.

author: robrenz
author_rank: Super Contributor
timestamp: March 23, 2015, 11:55:32 am
content: Bump

author: zapta
author_rank: Super Contributor
timestamp: March 23, 2015, 02:35:13 pm
content: robenz, what is the Versa Ohm? Is it a product you plan to sell? Was it discussed in earlier threads? If so, I must missed it.

author: robrenz
author_rank: Super Contributor
timestamp: March 23, 2015, 03:11:04 pm
content: It is a very small double 8 decade resistance box. I have been making 25 units on and off over the last couple of years. The beginning of the kelvin banana jack video below shows its general features. I will have more videos showing it in action. I am posting these construction videos so people can possibly use these techniques for their own projects.
Absolute angle calculation from gyro and accelerometer - Page 1
Forum section: electronics / projects

author: Amper
author_rank: Frequent Contributor
timestamp: April 28, 2020, 10:36:47 am
content: Hi! I hope this is the right category for this post since its not really an electronics question.Im working on a segway project and have toknow the absolute angle. This works beautifully via two accelerometer axis but this only works in static applications. As soon as there is a linear motion to the sensor, the angle is changing according to the total acceleration vector.Is there a simple way to correct for it or does newton say no?

author: Rerouter
author_rank: Super Contributor
timestamp: April 28, 2020, 11:01:39 am
content: It is usually called "sensor fusion" there are tons of libraries out on the internet for it, basically it is subtracting the effect of one from the other, in your case it would be subtracting the acceleration of the motor * the calculated angle of the gyro from the accelerometer output.The libraries basically put the accelerometer axis and the gyros rotation in the same space, so that rotation on the gyro rotates the output of the accelerometer to the same orientation, keeping things consistent over rotation, then when you have acceleration with no rotation it can be summed out, (a magnetometer would usually be added to provide a way to fight the drift of the gyro)
MCP3421 absolute maximum ratings - Page 1
Forum section: electronics / projects

author: mc172
author_rank: Frequent Contributor
timestamp: March 15, 2019, 02:24:14 pm
content: I'm looking at this datasheet:http://ww1.microchip.com/downloads/en/DeviceDoc/22003b.pdfTwo things are a bit confusing to me. On the second page are the absolute maximum ratings for the device.The datasheet says that the current on the input pins must not exceed 2 mA, but the input impedance is 2.25 Mso how could it ever get anywhere close? VDD max is 7 V...The only thing I can think it could be is when the inputs exceed VDD + 0.3 V and the ESD diodes start conducting, but 2 mA seems pretty low for that.The datasheet also says "output short circuit current.... continuous" and then 2 lines later says "output current..... 10 mA". Which is it?

author: wraper
author_rank: Unknown
timestamp: March 15, 2019, 02:30:42 pm
content: It means that ESD diodes are quite weak and are rated only for 2 mA.

author: wraper
author_rank: Unknown
timestamp: March 15, 2019, 02:33:29 pm
content: Max output current is not related to ESD diodes.

author: magic
author_rank: Super Contributor
timestamp: March 15, 2019, 06:35:47 pm
content: I would read it: don't allow output over/undervoltage or shorting to VCC while the chip drives low, if any of that causes the output current to exceed 10mA.Not sure whether shorting to VCC while the chip drives low causes that limit to be exceeded or not. Perhaps that's what they meant? Either way, it's a pathological situation which doesn't happen in normal operation.

author: mc172
author_rank: Frequent Contributor
timestamp: March 19, 2019, 05:51:42 pm
content: Thank you chaps.
Absolute Value Current Sense Amplifier Circuit? - Page 1
Forum section: electronics / projects

author: hal9001
author_rank: Regular Contributor
timestamp: March 20, 2022, 10:44:03 am
content: Is there a current sense op amp circuit to output the absolute value of the current in terms of positive volts. In other words even if current direction changes I want to know how much current is going through a current shunt but dont care about direction.Cheers!

author: StillTrying
author_rank: Super Contributor
timestamp: March 20, 2022, 11:45:02 am
content: You could connect 2 of the constant current outputs to the same output resistor.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 20, 2022, 03:34:53 pm
content: You need a current monitor and a simple absolute value circuit.Many RIRO precision opamps will work.The current sensing method you need depends on the current, system voltage and frequency..A simple method would be to use a high CMV differential amplifier (which you can home brew with loss of accuracy). This IC will work on a 120V RMS AC system

author: hal9001
author_rank: Regular Contributor
timestamp: March 21, 2022, 10:25:43 am
content: Quote from: StillTrying on March 20, 2022, 11:45:02 amQuote from: Terry Bites on March 20, 2022, 03:34:53 pmThanks!

author: Terry Bites
author_rank: Super Contributor
timestamp: March 22, 2022, 01:37:06 pm
content: You aresoright.There are exotic and more precise expensive versions I looked at before the penny dropped.https://www.analog.com/en/app-notes/an-105fa.htmlF(page 28) well worth a full read.Bidirectional Absolute Value Current Sense using LTC6101 or LTC6102.Seehttps://www.analog.com/media/en/technical-documentation/data-sheets/ltc6101.pdfpage 18 on boosting operating voltage if you need to.Orhttps://www.analog.com/media/en/technical-documentation/data-sheets/6102fe.pdf