hybridfree/eevblog-posts huggingface dataset:
Negative power supply - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: January 31, 2014, 02:15:53 pm
content: I tried to do dual power supply. The positive part works fine but the negative part is oscillating. I have attached the basic schematics . I don't have digital scope so I have drawn the output that I have scene in my analog scope . Please guide

author: Zero999
author_rank: Super Contributor
timestamp: February 04, 2014, 10:45:46 pm
content: QWhat a strange circuit.It oscillates because the phase shift is 180 at a frequency when the gain is above one so negative feedback becomes positive feedback. Add a compensation capacitor into the feedback loop to reduce the high frequency gain so the gain with 180 degree phase shift is under 1.
negative programmable reference voltage model recommendation - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: September 08, 2024, 11:21:55 am
content: Hello , I have this TL431 which makes a very good positive reference voltage 12V to what ever we want in that range as shown in the photo.Is there a similar model i could use to convert -12V into -2.5 in a similar amnner?Thanks.

author: Phil1977
author_rank: Frequent Contributor
timestamp: September 08, 2024, 12:00:00 pm
content: A shunt regulator as the TL431 works as well for negative voltages.Here is an example:https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/898175/tl431-negative-reference-voltage-generation-using-tl431
Negative Reference Voltage Problem with LM4040 - Page 1
Forum section: electronics / projects

author: Thomas_B
author_rank: Newbie
timestamp: February 28, 2021, 06:25:37 pm
content: Hello,I started simulating a circuit in Multisim and tried to use an LM4040 Shunt Reference as a voltage reference. For my project I need a positive and a negative reference voltage of +5V and -5V. The power supply is a split-rail supply with +/-12V.My template is this design:https://mutable-instruments.net/modules/ripples/downloads/ripples_v90.pdfAccording to the datasheet, positive and negative voltages should be possible with the LM4040. As you can see, the positive reference works fine, but the negative doesn't have the correct value and it oscillates.The Multisim oscilloscope shows the same picture.Can you explain the behavior of the simulation? Where is my error?Thank you in advance for your help.Cheers,Thomas

author: hugo
author_rank: Regular Contributor
timestamp: February 28, 2021, 07:02:12 pm
content: Try to increase C1,C2 to (100nF) or even more (1uF).You might also need to increase R1,R2 a little bit.

author: jbb
author_rank: Super Contributor
timestamp: February 28, 2021, 07:15:58 pm
content: Total guess: how good are the LM... spice models?I recently wanted to model a circuit with TLV431 (Texas Instruments) and found the model only worked right with the anode (?) connected to ground. So it worked fine for the ‘normal’ circuit and failed for a circuit referenced to a negative rail. Suggest you try moving the spice ground connection and see what happens.

author: Thomas_B
author_rank: Newbie
timestamp: February 28, 2021, 07:29:14 pm
content: You are right. In the template that I use and in the TI reference is a bypass capacitor of 100nF (not 10nF) mentioned.But unfortunately it slowed the oscilation down (as expected) but didn't help with the general problem. Maybe there is really an error within the SPICE model.Thanks for your advice.
Negative to Positive DC Voltage Convertor - Page 1
Forum section: electronics / projects

author: basit701
author_rank: Contributor
timestamp: May 24, 2015, 05:59:14 pm
content: Hello Guys!After sorting out the transformer configuration problem for my dual voltage supply, another problem exists now. The digital voltmeter i am using has three wires:1) +12Volt (to turn on the voltmeter)2) Ground3) Voltage MeasuringThe voltage is measured with respect to ground wire.However if i connect the voltmeter supply terminal to +12 V and ground and then measure - voltage it does not measure the voltage. The output voltage shown is zero. I was thinking to use op amp 741 inverting configuration with gain of -1 to convert the -ve voltage to +ve voltage but the op amp VCC and VEE limit is 20 volt and my output voltage is 20+.Any suggestions to resolve this issue?

author: Waff0l
author_rank: Newbie
timestamp: May 24, 2015, 06:23:03 pm
content: I say, take a different opamp which can operate at higher supply voltages like aLM2904-edit - which is still too small, also, does your DVM measure above +12V (its supply voltage)?

author: Zero999
author_rank: Super Contributor
timestamp: May 24, 2015, 06:27:42 pm
content: The LM2904 has a maximum total supply voltage of 36V which is no better than the uA741. In fact the uA741 (not the C version) has a maximum total supply voltage of 44V.
negative voltage amplifier - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: March 29, 2014, 11:51:26 am
content: I need to amplify negative voltage using direct coupled transistor amplifier. please post any suggestions and schematics Amplify 0 to -5V to 0 to -25V

author: acbern
author_rank: Frequent Contributor
timestamp: March 29, 2014, 01:06:51 pm
content: unless for a very specific reason that you need to use tranistors (tell us if so), the best and simplest approach is to use an opamp, set to gain 5. its not worth using transitors, at least not if you need precise amplification factor. There are many opamps available from e.g. TI that can handle the voltage.

author: Colin55
author_rank: Contributor
timestamp: March 29, 2014, 03:20:03 pm
content: Do you want to amplify the voltage or the current?

author: electros6
author_rank: Regular Contributor
timestamp: March 30, 2014, 05:39:59 am
content: amplify voltage

author: Zero999
author_rank: Super Contributor
timestamp: March 30, 2014, 04:51:35 pm
content: How much current do you want to draw?For low currents, a simple op-amp non-inverting amplifier with a gain of 5 will do.http://en.wikipedia.org/wiki/Operational_amplifier_applications#Non-inverting_amplifier
Negative voltage for a project - Page 1
Forum section: electronics / projects

author: Saitama
author_rank: Contributor
timestamp: July 04, 2019, 05:56:00 pm
content: Hello! I am designing a Lab bench power supply with OpAmps and i ran into a problem.The problem is that i need negative voltage for a differential amplifier, so naturally, I searched for a 7660, but could not find any in my region and buying from Ebay will take an eternity so I came here to ask.My input voltage is 32V and the Amp need -2V. I am looking for a circuit that is cheap and stable.Any suggestion is welcome.Thanks in advance!

author: Benta
author_rank: Super Contributor
timestamp: July 04, 2019, 06:14:23 pm
content: If it's an AC powered bench supply, you can make a small charge pump from the secondary with two diodes and two caps.

author: Saitama
author_rank: Contributor
timestamp: July 04, 2019, 07:34:20 pm
content: I already have a 32V unadjustable power supply, so i can't do that.

author: xavier60
author_rank: Super Contributor
timestamp: July 04, 2019, 09:30:44 pm
content: A CMOS 555 could drive the charge pump. The CMOS 555 will oscillate properly simply with a resistor from its output to pins 2 and 6 tied together, and a capacitor from pins 2 and 6 to GND.It can be powered with a dropper resistor and bypass capacitor with a shunt regulator across the -DC output.

author: Audioguru
author_rank: Super Contributor
timestamp: July 05, 2019, 02:22:33 am
content: I assume that your power supply will use AC electricity and a transformer. Then here is how a low negative voltage is made in another power supply circuit:
NEMA 11 stepper motor, one phase down - Page 1
Forum section: electronics / projects

author: gaoshenkoiie
author_rank: Newbie
timestamp: March 18, 2020, 09:22:21 am
content: For my dual extruder I useNEMA 11 stepper motors, 0.67 Amp/phase.These light stepper motors can easy go down when powered with a higher current as specified. Per mistake I fired one up with 1.5 amp and immediately one phase was gone.When it happens you can conclude this by measuring the resistance from the 2 phases. (see motor spec) Both phases should be close to equal. Mine should be 6 ohm and measured 2.3 and 6 ohm.Good luck printing

author: thm_w
author_rank: Super Contributor
timestamp: March 18, 2020, 09:40:26 pm
content: Good to know.What were you using to control the current, a pot on the stepper driver board or was this with a serial command to set the limit?What was your supply voltage?Wonder if its difficult to use a single motor for a dual direct drive extruder.
NEMS CLARKE 1302 A - Page 1
Forum section: electronics / projects

author: BOB KD0IJI
author_rank: Newbie
timestamp: October 28, 2013, 02:09:37 am
content: Hello All;,....... NEMS CLARKE 1302 A. Anybody have any idea where I can 'SERVICE' info. for this radio. Internet search seems no help.. I have one that is very noisey when tuning...THANKS for any HELP.. ...BOB... KD0IJI
neon bulb potting reliability? - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: August 16, 2017, 06:14:52 pm
content: Can you pot a neon bulb in epoxy? I made a modification of a small light bulb holder to house a neon bulb (by breaking the light bulb and soldering stuff in there)Can the neon bulb be potted with clear epoxy, or will this lead to some kind of thermal failure? I wanted to make it more robust, as the wires inside of the bulb are fairly wonky.

author: Zero999
author_rank: Super Contributor
timestamp: August 16, 2017, 06:24:56 pm
content: I don't see why the potting should cause a thermal failure, as neon lamps don't get very hot. If you think it's a problem, keep the current low.

author: Gyro
author_rank: Super Contributor
timestamp: August 16, 2017, 06:31:15 pm
content: No, it'll be fine, disipation is minimal. In the old days people (not me you understand, just people) used to pot bunches of them in resin blocks as flashing paperweights. Just remember though that neons don't last for ever.

author: floobydust
author_rank: Super Contributor
timestamp: August 16, 2017, 06:34:51 pm
content: As long as you don't use conductive epoxy, like JB weld.Extension cords have neon-lamps molded inside them as indicators and works fine.Instead, I use an LED and a resistor+shunt diode, as some chinese neon lamps they push them hard for brightness and they don't last that long. Flicker flicker.

author: CopperCone
author_rank: Super Contributor
timestamp: August 16, 2017, 06:41:28 pm
content: I like neon bulbs because its hard to see them going short circuit.I just potted it up to the base (bottom 1/5th or so )of the bulb, I guess it will be fine.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: August 18, 2017, 01:22:31 am
content: I looked at using a Christmas lamp holder thing to keep the leads apart. The neon lamps are a bit wider, so it may be possible to slightly drill out the lamp holder. Then at least the leads are held apart.
Neon sign PS with a pcb between the series aiding secondaries. Why? - Page 1
Forum section: electronics / projects

author: Qmavam
author_rank: Regular Contributor
timestamp: June 19, 2023, 03:57:13 pm
content: I have a switching style neon sign PS, it switches it 20kHz. It had no output and the secondary measured open. So I did the logical thing, I put it on the grill,and melted all the tar out of the transformer. What I found was the transformer and a pcb.I don't understand the purpose of the circuit.Let me back up a little, the PS starts with a 555 driving FETs connected to the primary, about a 200vpp square wave drives the primary. The secondary consists of two windings but at the center pint of these two windings is this circuit. I also added pictures of the whole thing.What does this circuit do?

author: Qmavam
author_rank: Regular Contributor
timestamp: June 19, 2023, 05:09:58 pm
content: BillyD, Zarhi, ataradov, nice to see you guys looking, Any ideas?

author: langwadt
author_rank: Super Contributor
timestamp: June 19, 2023, 07:16:38 pm
content: current limiting?

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 19, 2023, 11:09:27 pm
content: It looks like it imposes a small DC offset in one direction and then the other direction. Not sure what practical effect that would have.

author: Wolfram
author_rank: Frequent Contributor
timestamp: June 19, 2023, 11:15:38 pm
content: Could it potentially be to prevent beading (striation formation in the discharge) or mercury migration possibly? It's not very obvious from just the schematic. Is there any branding or a part number on the NST? A manual or product page might give some more clues.

author: Qmavam
author_rank: Regular Contributor
timestamp: June 20, 2023, 12:21:28 am
content: No labeling on either of the two I have.One would think current limiting, but the measured inductance would seem to limit he current to 6ma, which doesn't make sense, because I know it's output is higher than 6 ma.Thanks, Qmavam
Nerobro's Resume:  Mechanical and Electronic Projects.   - Page 1
Forum section: electronics / projects

author: Nerobro
author_rank: Contributor
timestamp: November 23, 2010, 05:22:27 pm
content: So, I am a noob at this. I will probably always be a noob in electronics. But I've done a few things over the years.We'll start with what I am most proud of. It's not directly "electronics" but here we go.This is mini-mill based on the plans from:http://www.crankorgan.com/brute.htmHere's the build process:http://www.practicalalchemy.org/~nerobro/brutemill.htmlOh, and video of it taking a cut in aluminum:Most of what I've done with electronics has been with power electronics. I think the most interesting to this crowd would be building a regulator/rectifier unit for a motorcycle. Most motorcycles have a permanent magnet alternator, so power output is directly related engine rpm.So the trick is to transform 12-130vac 3phase to smooth clean 14v DC. At least it's 3phase input. At like 6-60,000hz, or something crazy like that.The solution was to use two two phase rectifiers, and three SCR's.And here's how I packaged it:My friend and I built two, and they worked. Very stable voltage output. The cases we chose just didn't really do the job well, so at some point I'll revisit that.In an effort to make a bicycle headlight, I bought the parts to support natsemi's simple switcher.And I made it work. I later put that circuit onto perfboard and hooked it up to 56 LEDs. It's neat, and bright, but it wasn't all that useful when compared to some real flashlights. I was just happy it worked. And I was happy I managed to make some SMD components work on a breadboard.I also built the capacitor tester from jytech, same people who make the avr based occiliscope kits. .... I also tried to make the o-scope too, but failed somewhere along the line. I think I burst a SMT cap.At least the cap tester works!I've got a couple arduinos that I've been messing with. Which is really more coding than hardware work. It's really satisfying to be able to swing some code in a few minutes and get servos to do what I want over a serial console.
Nest protect 2nd gen POE - Page 1
Forum section: electronics / projects

author: Stealthrt
author_rank: Regular Contributor
timestamp: July 10, 2018, 05:48:57 pm
content: Hey all i am looking for some advice in how to go about my project with a Nest Protect gen 2.In my home i have ran cat6 wire to all 3 locations that require a smoke detector. These cat6 cables are connected to a POE switch for powering the Nest Protect.The version i picked up for the Nest Protect is the battery version. I am wanting to convert the battery to the POE in order to power it by POE instead of battery. The Nest Protect uses 6 x AA batteries that equal ~9vdc total.I am converting the POE to 9vdc via a converter:However my question is- do I need to wire up the 6 battery placers in parallel or series? It would seem that the Nest Protect AC version has only 3 x AA for power backup. Not sure if that matters in my case or not.I would like to keep a battery backup just in case the POE goes out for whatever reason. The POE has a battery backup as well.
Nestronic Video Game Music Synthesizer (Alarm Clock) - Page 1
Forum section: electronics / projects

author: dkonigs
author_rank: Regular Contributor
timestamp: August 05, 2018, 06:18:44 am
content: So this is a project I've been working on for most of this year. Its a crazy attempt to build something that combines a retro CPU with modern hardware, and its also my first foray into no longer being afraid to work with surface-mount components. I figured it was time to start sharing it more broadly, so here goes...The Nestronic is a hardware VGM (Video Game Music) player for the NES APU (Audio Processing Unit), with a real-time clock. It is based on the ESP32 microcontroller, combined with an original RP2A03 (6502-based NES CPU). The two processors communicate with each other over I2C.For more information about the project, at least through revision A of the hardware, please see these blog posts:http://hecgeek.blogspot.com/2018/02/nestronic-1.htmlhttp://hecgeek.blogspot.com/2018/03/nestronic-2.htmlhttp://hecgeek.blogspot.com/2018/05/nestronic-3.htmlhttp://hecgeek.blogspot.com/2018/07/nestronic-4.htmlI just finished a video covering the complete assembly process for the revision B hardware:https://youtu.be/UlO0NQTAaJUAll of the project designs and source code is here:https://github.com/dkonigsberg/nestronic(Yes, I even used issue reports to describe hardware changes between revisions.)If anyone is curious to learn more about the VGM format, it is described here:http://vgmrips.net/wiki/VGM_Specification
Netgear Orbi RBR50 and satellites - Unstable WiFi - Anyone with experience? - Page 1
Forum section: electronics / projects

author: AndersJ
author_rank: Frequent Contributor
timestamp: November 15, 2020, 06:44:11 am
content: Brand new Orbi RBR50 router with two RBS50 satellites.WiFi comes and goes now and then, many times per day.Satellites take up to an hour to connect.Cabled connections to router work flawlessly.I see nothing in the RF spectrum that could interfere.Also shaky with router only, no satellites.Any ideas , anyone?
Network cable category wtf - Page 1
Forum section: electronics / projects

author: andtfoot
author_rank: Unknown
timestamp: June 26, 2014, 12:04:56 pm
content: I'm just doing a training thingie (Telecommunications) for work, and littered throughout it are... odd ways of describing things.Is it just me or does questions 4 and 5 in the quiz not make sense? (It's also how it's described in the text)Now a half-educated guess would have me say that gigabit Ethernet is transmitted at the same frequency, regardless of the cable used (let alone that it's not the cable itself that is transmitting).

author: madires
author_rank: Super Contributor
timestamp: June 26, 2014, 12:19:04 pm
content: The correct answer for that bad Q4 is Cat 5e. Cat 5 is specified for 100MHz but not for GigE usage. The minimum required category for GigE is 5e. The trainer failed the testBTW: The clock rate for GigE is 125MHz for each TP. It's the same for FastEthernet. Second fail

author: Precipice
author_rank: Frequent Contributor
timestamp: June 26, 2014, 12:26:17 pm
content: Wikipedia thinks not -http://en.wikipedia.org/wiki/Gigabit_Ethernetdown at the bottom, the difference between 1000BASE-T and 1000BASE-TX

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 26, 2014, 12:39:46 pm
content: Maybe"What category of cable is characterised to 250Mhz." Might be a better question.Most cables aren't intentionally transmitters.

author: Fsck
author_rank: Super Contributor
timestamp: June 26, 2014, 12:43:34 pm
content: Quote from: HackedFridgeMagnet on June 26, 2014, 12:39:46 pmyeah, the wording makes the incorrect fundamental concepts worse.

author: madires
author_rank: Super Contributor
timestamp: June 26, 2014, 12:50:29 pm
content: You can run GigE on Cat 5, but it's not remommended. The specs of Cat 5 are at the fringe of what GigE requires. Long cables or poor installation (too small bend radius and so on) will give you broken frames and a lot of FCS errors. Anyone involved in structured wiring of datacenters will tell you to use Cat 5e at least for GigE. Cat 5e has better specs and allows some abuse of the cable without causing too much trouble.

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 26, 2014, 01:08:22 pm
content: Just another example of being "copy edited" by non-technical people who likely "corrected" what they thought was "improper grammar". Alas, you find this kind of problem in many places. I call this "technical entropy."

author: Fsck
author_rank: Super Contributor
timestamp: June 26, 2014, 01:12:29 pm
content: Quote from: madires on June 26, 2014, 12:50:29 pmsame way that cat5e can work in clean environments in short runs for 10G.
Networks for peaking frequency response? - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 11, 2021, 03:54:03 am
content: Anyone know if there's a general (n-pole) topology for peaking, with one port C-loaded, the other R-loaded?The famous T-coil method applies forboth ports C-loaded only, with the R load being incidental (typically bias). I want a network which peaks the response into the R alone (a wideband RF power amp is an illustrative example).The only method I'm currently aware of, is series peaking, which stinks (~50% bandwidth gain even with 4 poles in your basic ladder topology).Bit of an aside, there is one method, a distributed amplifier. But I mean for a single amp only.I do have a bib reference this time!Wideband Amplifiers, Starič and Margan. Part 2 gives analysis of several useful peaking circuits. I kind of doubt that these are exhaustive among useful peaking circuits, though?Tim

author: srb1954
author_rank: Super Contributor
timestamp: February 11, 2021, 05:13:22 am
content: Quote from: T3sl4co1l on February 11, 2021, 03:54:03 amHave you also looked at the Vertical Amplifier Circuits handbook in the Tektronix Circuit Concepts series?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 11, 2021, 05:55:33 am
content: Those are entirely of the both-C-load type.Tim
Network/Safety FPGA platform - Page 1
Forum section: electronics / projects

author: laugensalm
author_rank: Regular Contributor
timestamp: January 28, 2018, 02:34:11 pm
content: Hi there,I thought I'd share this with the experts: I've designed a mini networking capable System on Chip on FPGA a while ago, mainly for UDP-video streaming. After having to somewhat follow the IoT hype, I've crammed it all into a Spartan6-LX9 for some test & measurement stuff that we usually run on small embedded Linux modules (which aren't obviously totally ready for safety/realtime). This time it's just a FPGA instead, speaking the same protocol (our in house 'network property protocol') as the 'smarter' Linux.So now it's all baked into a board, called "netpp node", which is currently available for eval after approx. 5 months in the test loop.The fun stuff about it, as a short outline:Super compact program code based on pipelined ZPU(next generation) architecture, means, GCC supportFull program main loop can be put in simulation (verification way above MISRA checks, etc.)Speak to the thing using LabVIEW, DLL, Python, like querying an Analog value:val = node.ADC.Value.get()Lots of flexibility for other interfaces or specific hardware-DSP-UnitsPainless firmware upgrade over the network or on-board-USB-ICEI use it for mostly networked controlling (sensor networks) and testing, one nerdy application was, to drive a few WS2812 LED strips in parallel with the precise timing they require - while the CPU is doing some color interpolation fun. I guess there's plenty more ideas to come up with. I'm not there yet making it a community thing like the Papilio, but am open to any input...Fore more info:http://section5.ch/netpp-node. Cheers!
Neurbugs, neural network bugs - Page 1
Forum section: electronics / projects

author: cur8xgo
author_rank: Regular Contributor
timestamp: June 22, 2019, 12:33:44 am
content: If this is in the wrong place please just delete thanks sorryThis is my totally for fun, totally un-researched, un-homeworked, off the cuff neural network life simulatorThink of a playing field, like a football field.Randomly disperse "bugs" on itRandomly disperse food on itEach bug can see whatever the next object in its line of sight (also its movement heading) is. That object could be a wall or a piece of food.Each bug has two input neurons connected to its eye, one for "food" one for "wall"Each bug has two output neurons, one for "heading rate of change" (heading is for movement and seeing), the other is for velocityThe neuron weights are randomized.Let the games begin!Each "frame" of the game is like an RPG. All the bugs get to "see", update their input neurons, update their output neurons, and then "move". Then the frame is done.On the next frame, things like bug energy are deducted or added (if they stepped on food). Bugs with zero energy die.Once all the bugs are dead or all the food is gone, that "game" is over. A new one is started with the same bugs, but new random locations for food and bugs.This repeats until an "epoch" is reached (just a number of games).Then all the bugs are evaluated according to how much they ate and where they rank compared to the other bugs. Loser bugs have their neurons erased and randomized. Good bugs "mate" with the top-scoring bug.Then the next epoch starts and it repeats.Note you can add the option of randomly sprinkling "wall" or even placing a long section of fixed wall to make their task harder.I've gotten them to evolve pretty quickly to be able to eat more than 95% of the food. Its interesting to watch the stats as the percentage eaten goes up, the amount travelled goes down, etc..Anyways it would also be cool to plot the statistics over time and see what sort of oscillations occur. You can get drastically different evolutions each time you run it since it seeds the first neurons randomly. "Gradient descent" I guess.This compiles in codeblocks on Windows XP. Also included is a compiled exe (its a console app).FYI: the "spectating" threshold is what ratio of food eaten/food available must be reached in order to allow manual viewing of the playing field so you can watch your bugs do their thing..this allows much faster evolvingNote that if things dont seem to be evolving fast, just stop and restart with a new random seed. On one run it was stuck at 0.43 ratio. I stopped and restarted it and got to 0.95 ratio in 400 games (about 5 seconds)I'm looking for any advice on how to make this better. Its a fun toy and could easily be modified. I think it has some "bugs" though..(pun intended). I tried adding a feature where the bugs could shoot each other but there started to be strange things like bugs randomly teleporting. But that feature is disabled now ( code is still there but commented out)..otherwise it seems to work okay.
Neurology Science book for wider experience, (as an EE) - Page 1
Forum section: electronics / projects

author: RJSV
author_rank: Super Contributor
timestamp: August 30, 2021, 01:25:43 am
content: Hi folks, got a nice book to review (a little).I've purchased an easy read book on Neuroscience, I've been waiting to read. Looking for some better / novel ideas, on CPU architecture and number engine (ALU arrays).By author Frank Amthor, titled"Neuroscience for Dummies", I had a friend place order on-line (my eye doctor's selection!)So, part of what I liked, is the book dispelled a bunch of false assumptions, such as that the RETINA passes a full-field image, up to brain stem, etc.But apparently, actual (visual) function acts as an ongoing sifting out, of only new or newly changed image components.Concepts like that have helped me visualize and re-form some basics, on the electronics / CPU side.Right now, I've been considering what could be a 'neurological based 6502 processor, keeping many aspects of microcode, while doing BUS functions on a completely different basis (from binary decoding etc.)
Never studied this - Page 1
Forum section: electronics / projects

author: Jozef
author_rank: Contributor
timestamp: May 19, 2013, 07:27:03 pm
content: HelloWhat makes an o'scope probe has higher bandwidth than another? or more generally what makes up a circuit bandwidth? materials? filters? and where does the higher cost for higher bandwidth go?Thanks a bunch!

author: Rasz
author_rank: Super Contributor
timestamp: May 19, 2013, 08:05:23 pm
content: i think dave did a clip on probe impedance and why high bw probes are x10

author: w2aew
author_rank: Super Contributor
timestamp: May 20, 2013, 12:31:02 am
content: Quote from: Jozef on May 19, 2013, 07:27:03 pmOscilloscope probe BW is governed primarily by the parasitic capacitance at the probe tip. You may want to review this video on 10x probes:Dave did an excellent video recently regarding a tear-down of a 1x/10x probe that goes into even more detail, including the special lossy coax used:Bandwidth in general is limited by the reactive components (either real or parasitic) in a circuit. I did a video a while ago that analyzed the low-pass and high-pass frequency corners of a simple common emitter amplifier circuit:

author: Jozef
author_rank: Contributor
timestamp: May 20, 2013, 04:59:04 am
content: Good videos! Thanks!
new $5 ESP8266 WIFI IC SPI module anyone using with Arduino? - Page 1
Forum section: electronics / projects

author: ESP8266
author_rank: Newbie
timestamp: September 01, 2014, 07:55:58 pm
content: Looking for people to help with building an Arduino library for the new ESP8266 low cost WIFI interface IC. Its very new and very cool.... you can see more information atwww.esp8266.comand you can also log in and help at that website. I am very excited about this new IC as its cost is insanely low... hope more people can offer projects using it.Richard.
New AliExpress seller extremely cheap, bargain to get feedback or scam? - Page 1
Forum section: electronics / projects

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 01, 2023, 06:41:17 am
content: Just spotted this seller yesterday, amazing prices but 0% feedback.I know it's a common practice to drop prices initially to gain feedback and trust, so it might be a real bargain... Or a total ripoff!I bought this RK3588S SBC feeling like I was stealing it:**Deleted** (scam)Any guesses?

author: bingo600
author_rank: Super Contributor
timestamp: May 01, 2023, 07:49:43 am
content: And including free UPS shipping in the price .... Hmmmmm/Bingo

author: BravoV
author_rank: Super Contributor
timestamp: May 01, 2023, 07:54:48 am
content: Quote from: DavidAlfa on May 01, 2023, 06:41:17 amWith such deal .. if it goes flopped, say it was a scam.The real question is, will you whine here in this forum about how bad and how evil the seller is ?

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 01, 2023, 08:54:25 am
content: Do I need to hire Sherlock Holmes to investigate every seller out there?Nope! That's AliExpress business!I will rant about null Aliexpress buyer protection if I get scammed and they do nothing.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: May 01, 2023, 09:38:06 am
content: Maybe a new entrant trying to get noticed?Let us know how you go, I'm interested. I think AliExpress will cover you. Fortunately I can resist this purchase.

author: ifonlyeverything
author_rank: Regular Contributor
timestamp: May 01, 2023, 11:03:08 am
content: Even sellers with feedback are unreliable, because they can delete your negative review.

author: 2vlado
author_rank: Newbie
timestamp: May 01, 2023, 02:00:48 pm
content: Don't forget to film unpacking the package and first test of the device. Having a video proof saved me once from a scam. Seller sent me a different product than what I ordered.

author: wraper
author_rank: Unknown
timestamp: May 01, 2023, 02:39:12 pm
content: Best case you'll get order cancelled. Worst case fake tracking number.

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 01, 2023, 02:40:33 pm
content: Yep, I learned that 15yrs ago, in the old eBay times when sellers were sending bricks, sand, stones...

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 02, 2023, 05:19:52 pm
content: SCAM!The good were shipped 24 earlier than my order and delivered to France four days later.Aliexpress agents's IQ is questionable, I had to tell them the same thing like 5 times..."But it shows delivered sir""Yes, but 2000km away, in a different country!""Let me check that for you""Tracking shows delivered, did you receive the correct goods?""I received nothing, ask a guy called Jean-Pierre in France LOL"Ages later:"I see, let me open a claim"At least they've stepped in.I knew it was too nice to be true but anyways:
New Breadboard! - Page 1
Forum section: electronics / projects

author: Falcon69
author_rank: Super Contributor
timestamp: March 20, 2014, 09:33:42 pm
content: Thought I would share.Just got done making myself a new breadboard. Ordered up seven 830 hole breadboards, a piece of acrylic, some screws, bumper pads, and 5 binding posts. Total cost for everything was about $55.00Didn't turn out perfect, but well enough.What do you think?Jason

author: nanofrog
author_rank: Super Contributor
timestamp: March 20, 2014, 10:13:53 pm
content: Looks nice to me.Where'd you source the breadboards from (name brand or Chinese)?

author: Falcon69
author_rank: Super Contributor
timestamp: March 20, 2014, 10:16:38 pm
content: Chinese (aka, eBay). I don't do prototyping very often, so I figured they should work just fine, for awhile. I just needed a big board right now for a project I am working on.

author: Bored@Work
author_rank: Super Contributor
timestamp: March 21, 2014, 10:17:26 am
content: Quote from: Falcon69 on March 20, 2014, 10:16:38 pmMust be a big projectBut if it works for you it works for youQuote from: Falcon69 on March 20, 2014, 09:33:42 pmHave you considered adding some other type of connectors to the board, e.g. BNC or 2.54 mm headers? Or whatever makes sense for your project?Other fun stuff to add if it makes sens- Front panel to hold pots, meters, sockets. Similar tohttp://gsmserver.com/shop/equipment/soldering_sssembly/ancillary_equipment/round_hole_bread_board_2420_tie_points_proskit_bx_4135.php- Power supply- Some basic signal generator

author: mathsquid
author_rank: Frequent Contributor
timestamp: March 21, 2014, 01:33:04 pm
content: Very nice! I recently put a few boards together into a frame so I could have an easily movable prototyping board for a midi sequencer. It's not as nice looking as yours but it works and it's pretty rugged.
New capacitor shorted? - Page 1
Forum section: electronics / projects

author: MathWizard
author_rank: Super Contributor
timestamp: March 23, 2021, 08:17:47 am
content: I was just matching some 33nF green polyester 630V caps, for low voltage audio, (it's either these or cheap ceramic caps, so IDK)But anyways 1 of them I took from the bag was dead short, there's no way I ever used any of these caps on anything near 630V. These were just cheap ebay caps.Makes me wonder about all the cheap parts I never test. I guess I really should check caps at least, but who has the time for that......oh just another reason to stop buying from ebay and amazon

author: Miyuki
author_rank: Frequent Contributor
timestamp: March 23, 2021, 09:13:46 am
content: There is a reason why they cost a fraction of what a reputable distributor will wantCan be just some old stocks, can be rejected batches, or some recycled whateverWhen manufacturing with cheapest parts It is expected to test final products and just throw some percentage of it to scrap binOr to buy more expensive parts and have just a fraction of failed onesIt all depends on your calculation of profit

author: wizard69
author_rank: Super Contributor
timestamp: March 24, 2021, 06:30:37 pm
content: Quote from: MathWizard on March 23, 2021, 08:17:47 amThere will always be a certain percentage of failed components in a production batch. Ideally they don't get into the wild, however some manufactures just don't care. If there is a large number of failures a legitimate manufacture will take the product back.However the problem with E-Bay is that you are seldom dealing with the manufacture nor an authorized distributor. The odd thing here is that sometimes you get the best results on E-Bay by dealing with guys doing factor closeouts and inventory reductions and don't really know what they are selling. You can get lucky on E-Bay but it isn't the palce to buy new production.QuoteWell don't use E-Bay for production parts that you expect to be of high quality. Amazon is a different story and you really need to pay attention to whom the actual seller is.
New DIY Metcal compatible soldering station - Page 1
Forum section: electronics / projects

author: fireworks
author_rank: Contributor
timestamp: June 14, 2018, 02:02:03 pm
content: There is a new open source project for a DIY Metcal compatible RF generator:https://github.com/SergeyMax/SolderingStationIt also has a Youtube video:The output power is 80W, so it's higher than the 40W or so of a MX500.Looks very promising!

author: apblog
author_rank: Regular Contributor
timestamp: June 15, 2018, 12:26:06 am
content: Dumb question... 80 Watts is a lot of RF power, or so I recall from my days of setting up antennas on rooftops. We were warned to be careful of 100 Watt microwave dishes, for example.Is this thing gonna roast my eyeballs?Like this guy —>OK, obviously not, but WHY not? The idea of an RF soldering iron has always scared me a bit.

author: David Hess
author_rank: Super Contributor
timestamp: June 15, 2018, 12:36:11 am
content: Even 5 watts of RF can give a serious RF burn but in this case all of the RF is absorbed in the soldering tip instead of being radiated so it is not a problem. It is no more dangerous than applying 80 watts of RF to a dummy load.

author: Towger
author_rank: Super Contributor
timestamp: June 15, 2018, 04:08:29 am
content: 80w is what the newer 5200 base stations output and handles support.

author: CristopherD
author_rank: Newbie
timestamp: June 16, 2018, 04:42:33 am
content: how does this compare to the older metcal irons?i think they had 433mhz and 13.56mhz?There was a DIY metcal thread herehttps://www.eevblog.com/forum/projects/diy-metcal-13-56-mhz-rf-supply/500/

author: helius
author_rank: Super Contributor
timestamp: June 16, 2018, 06:48:25 am
content: The Metcal products with F connectors (including all the original ones from prior to the OK Intl acquisition) are 13.56 MHz (ISM band).Some of the newer products have three-pin circular connectors and operate at 450 kHz (SRD band for avalanche beacons). This system was mainly developed, as I understand it, to better compete with the prices of ceramic-cartridge products like Hakko or Weller.

author: rfmerrill
author_rank: Regular Contributor
timestamp: October 04, 2020, 07:42:10 pm
content: Sorry for necro, but did anyone actually try building this? I just made a big post on my build in this same subforum here:https://www.eevblog.com/forum/projects/i-built-the-diy-metcal-compatible-soldering-station/
New EEVBlog Meter, old meter, and scope - all give different readings? - Page 1
Forum section: electronics / projects

author: .frank.
author_rank: Newbie
timestamp: July 04, 2016, 07:07:40 pm
content: No clue what's going on here - maybe someone can watch this video and throw a dog a boneNew eevblog meter gives one voltage, old meter gives another, and scope gives yet a 3rd.Right click and SAVE this video, don't try and stream it.http://cia.spacetechnology.net/blog/my-question/question.mp4

author: German_EE
author_rank: Super Contributor
timestamp: July 04, 2016, 08:57:53 pm
content: "A man who has a clock knows the time, a man who has two clocks is never sure"Segal's LawThe two meters have a different response to the 23 KHz signal riding on the top of the DC so your DC measurements may therefore be different. I also suspect that the EEVBlog meter cannot measure a 23 KHz signal on AC which is why your AC measurements are so weird.As for your changes in current drawn, the meters provide a capacitive load across a 23 KHz signal.The correct reading is the one provided by the scope.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2016, 11:34:37 pm
content: What he said. ^As soon as you get high frequencies then forget the multimeter. Even the great Fluke 87 can only measure up to 5kHz at those voltages.The oscilloscope is the one giving the correct voltage reading.The current draw? Even a slight load on the output could drastically change the efficiency.

author: .frank.
author_rank: Newbie
timestamp: August 10, 2016, 02:34:44 am
content: Sorry for the late reply. You guys were correct. The multi-meter just cant handle that frequency range (neither of them) - scope was right!
New ESP32-S3 based PCB, open to suggestions - Page 1
Forum section: electronics / projects

author: aaronw
author_rank: Newbie
timestamp: May 15, 2022, 04:04:03 am
content: I still consider myself a beginner in designing PCBs and I have a number of questions regarding one I'm currently working on.First of all, this PCB is constrained as to its dimensions so it is quite dense, with components on both sides. I made a previous version of this board which has worked well.This PCB is built around an ExpressIF ESP32-S3 microcontroller and is designed to be able to drive a bunch of WS2812 type LEDs among other things. It contains a digital microphone, stereo speaker output, accelerometer/gyroscope/compass, a 1.2A, 3.3V switching supply, 12V 500ma boost supply with PWM (for fans), 5V I/O (6 channels), one RGB WS2812 type status LED (with output available to extend), a micro SD card, I2C I/O, and 12 additional GPIO pins connected to an i2c expander to trigger on external inputs. There's also a switched 5V output. It's a 4 layer board but I was able to minimize the number of traces requiring an inner layer.While I have a dedicated ground plane but am somewhat worried about possible significant noise introduced by the wi-fi antenna. Do I need to worry about this, especially with the i2s digital amplifier located so close?Did I go overboard with the vias? What about the ground floods on the front and back of the PCB? I am open to any suggestions, especially in regards to grounding.It's designed with KiCad 6.0 and can be found athttps://github.com/aaronw2/led-controller-v4and is still a work in progress and will be for a while since some key chips are currently unavailable.I had a previous version of this board based off of an ESP32 Wrover made which generally works well, but I haven't pushed wifi hard yet.

author: H.O
author_rank: Frequent Contributor
timestamp: May 15, 2022, 06:04:59 am
content: From which direction is the microSD card inserted? It looks like U301 may be in the way.

author: aaronw
author_rank: Newbie
timestamp: May 15, 2022, 06:10:59 am
content: I have a 3-D rendering that shows that there is plenty of clearance. U301 is low enough that the micro SD card will safely clear it. I have found the KiCad 3D rendering support to be invaluable.

author: tepalia02
author_rank: Regular Contributor
timestamp: May 16, 2022, 10:37:32 am
content: Regarding the noise reduction, I feel that this thread may give you some ideas:https://www.esp32.com/viewtopic.php?t=9613If you also want to test the other features of ESP-32, such as the touch sensor, you can perform the small test mentioned here:https://www.theengineeringprojects.com/2021/12/esp32-capacitive-touch-sensor.html
New Exar 2206 different than old 2206? - Page 1
Forum section: electronics / projects

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 06, 2013, 07:14:42 pm
content: I'm pretty annoyed! I needed a quick and dirty oscillator and power amp for someone and did basically the data sheet circuit for a XR-2206 single supply sine wave oscillator plus a power amp IC. I prototyped it with parts I had on hand and it worked perfectly. The supply voltage was 16 VDC. My new parts came in and the circuit was unstable. The new Exar parts seem to have a maximum voltage of about 11 volts before the timing goes unstable at low frequencies. The data sheet says the part should work to 26 VDC, just as my earlier chips do. I haven't found any other work-around than lowering the voltage. This will get me by, but isn't optimum. Does anybody know anything about this problem? I know the chip is obsolete but there seem to be plenty out there and its very handy for a quick cheap sine wave. Were the last runs defective or used a different process?

author: Bored@Work
author_rank: Super Contributor
timestamp: January 06, 2013, 08:06:15 pm
content: Maybe you got a counterfeit part?

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 06, 2013, 10:05:29 pm
content: Interesting thought. I bought a tube from Jameco, who's usually pretty good, but they also carry a lot of hard to get stuff so maybe they got lot of questionable origin.

author: free_electron
author_rank: Super Contributor
timestamp: January 07, 2013, 12:40:41 am
content: xr2206 is obsolete. any part you buy is old stock. Exar ceased production of this thing in 2011.

author: poorchava
author_rank: Super Contributor
timestamp: January 07, 2013, 07:02:04 am
content: I remember that I have used that chip for my master's thesis as 100kHz 1Vpp signal source. i remember that varying from device to device (had 5 of them from the same batch) i could observe more or less severe spike-like distortions on top and bottom of the sinewaves.
New free SPICE, QSPICE - Page 1
Forum section: electronics / projects

author: moffy
author_rank: Super Contributor
timestamp: September 01, 2023, 10:23:46 am
content: I have just downloaded QSpice, which is free, and it appears to be written by one of the authors of LTSpice. It appears more flexible than standard SPICE in that it allows the direct entry of either C++ code or Verilog into modules which it then compiles into a custom DLL for the simulation. A link to the video is included.

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 01, 2023, 12:34:50 pm
content: https://www.eevblog.com/forum/eda/mike-engelhardts-new-spice-simulator-qspice-is-out

author: moffy
author_rank: Super Contributor
timestamp: September 01, 2023, 11:18:28 pm
content: Thanks for that I must have missed it previously.

author: moffy
author_rank: Super Contributor
timestamp: September 01, 2023, 11:35:03 pm
content: Just ran the audio amplifier example with 14 transistors and passives, very fast, 0.136 seconds compute, and the results displayed a couple of seconds after that.
New gel to indicate corrosion on PCB´s - Page 1
Forum section: electronics / projects

author: Bloch
author_rank: Unknown
timestamp: April 21, 2013, 06:20:27 pm
content: Not sure if this have a interest to this forum ?.QuoteThe complete article herehttp://ing.dk/artikel/gel-sladrer-om-korrosion-paa-printkort-158000or via google translatehttp://translate.google.com/translate?sl=da&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&eotf=1&u=http%3A%2F%2Fing.dk%2Fartikel%2Fgel-sladrer-om-korrosion-paa-printkort-158000

author: ddavidebor
author_rank: Super Contributor
timestamp: April 21, 2013, 07:47:52 pm
content: interesting me only if i can make it

author: Bloch
author_rank: Unknown
timestamp: April 21, 2013, 08:00:11 pm
content: Quote from: ddavidebor on April 21, 2013, 07:47:52 pmI am sure you can - why not call them and ask for the recipe

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: April 21, 2013, 08:22:15 pm
content: It sounds inresting.but i am not sure about this but i think that corosion on pcbs is easily trackable by eye... correct me if i am wrong.

author: ddavidebor
author_rank: Super Contributor
timestamp: April 21, 2013, 09:53:22 pm
content: Yes it is, and i think oxide-relevant is not a new thing in industry