hybridfree/eevblog-posts huggingface dataset:
powerline filter with prongs - Page 1
Forum section: electronics / beginners

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: June 02, 2019, 05:26:33 am
content: Is there a power line filter similar to thishttps://www.amazon.com/dp/B073RLXRPBbut with prongs which go straight into a wall outlet instead of solder lugs? This is for a mains powered speaker which is noisy on mic input setting.I tried wraping the mic cord into 2 ferrite torroids at different ends and the power cord with a ferrite rod but it seems there simply isn't enough inductance to remove the noise or its not an issue from the power line. There are several products available on amazon which claim to filter mains power but they don't list any of the reactive filter elements inside nor the noise attenuation - digikey seems to only have solder lugs and module filters.

author: bob91343
author_rank: Super Contributor
timestamp: June 02, 2019, 06:32:10 am
content: Just how sure are you that a filter on the power line is what you need? What is the noise you are hearing?I have several power line filters in my junk box and have never found the need for them. They have come from things like copy machines, PC monitors, printers, and such. Being small, they don't have a lot of inductance and probably attenuate best in the HF range.Some power strips have filtering inside.If you insist on a box to plug in, you could build one. Being a one-off you probably needn't worry about meeting electrical code requirements.

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: June 02, 2019, 10:39:34 pm
content: Quote from: bob91343 on June 02, 2019, 06:32:10 amNoise emanates regardless of volume the mic channel is set to akin to whats known as static noise.

author: soldar
author_rank: Super Contributor
timestamp: June 02, 2019, 10:55:14 pm
content: Quote from: LaserTazerPhaser on June 02, 2019, 10:39:34 pmCould it be a ground loop problem?https://en.wikipedia.org/wiki/Ground_loop_(electricity)

author: bob91343
author_rank: Super Contributor
timestamp: June 03, 2019, 12:07:16 am
content: If the gain does not affect the noise, it's probably a noisy component.Someone gave me a Fender guitar amplifier that had loud noise in the output. I replaced the offending 4558 chip and it's like a new amplifier, clean and quiet.
Powersupply + Input via network cable - Page 1
Forum section: electronics / beginners

author: Chaos_Klaus
author_rank: Contributor
timestamp: November 08, 2015, 10:47:28 am
content: Hi there,I have a question regarding network cables.But first, here is what I am doing: I am building two devices. Device1 is basically just a powersupply that generates all the voltage rails I need (+15V,-15V,+5V analog, +5V digital, AGND, DGND) and it also has an optical ADAT input.Device2 is connected to device1 via some cable and recieves the ADAT-Stream. It decodes the stream, uses DACs to get audio signals, mixes them together and outputs everything to a headphone amplifier. In fact multiple devices2 will be connected to device1.This is meant to be a monitoring solution when recording audio with multiple musicians. I just route out audio 8 channels via ADAT and every musician can do his headphone mix himself.There is commercial products that do this. They pretty much all use CAT5 network cables to connect the external devices to the central hub and the external devices don't have their own power supply. So the power must be drawn through that network cable.Now here is my question:If I run my voltage rails through this cable (5m to 10m) won't I pick up a lot of noise? Most of the CAT5 cables are unshielded.If I run my digital ADAT signal in the same cable as the powersupply for my analog circuitry, won't that polute my supply rail aswell?. I mean, I would maybe not have a supplyrail and the digital signal in the same twisted pair, but the other cables are still close by.EDIT: I expect currents of around 100mA per rail, nothing more than that. I read that CAT5 cables can handle a lot more.
Powersupply problem or is it the multimeter?  - Page 1
Forum section: electronics / beginners

author: x_marx
author_rank: Contributor
timestamp: December 19, 2022, 11:52:34 am
content: Hi guys!So I bought a led powersupply (5v) from AliExpress and an amazon 'commercial' multimeter for an led strip project (controlling led strip with a Pi).When I measure the voltage output of the led powersupply between 'ground' and '+V', it's showing like 1.3V. But, when I measure between +V and -V, it's showing 5V.The powersupply have Line, Neutral (for AC 220V input) followed by Ground, -V (2 nos) and +V (2 nos) terminals.I was thinking than the voltage between +V and ground would be 5V but it's not the case here.Am I dumb or the powersupply is faulty?Any comments?https://a.aliexpress.com/_mL3S9OaI got the 30A version btw.

author: wasedadoc
author_rank: Super Contributor
timestamp: December 19, 2022, 12:03:56 pm
content: The answer to your question in the title is neither. The answer to your closing question is the first of the choices you offer.The dc output of those supplies is floating. Not referenced to ground. If you want the + or - side to be at ground potential you just have to connect it to the incoming ground yourself.

author: x_marx
author_rank: Contributor
timestamp: December 19, 2022, 12:10:59 pm
content: The powersupply says it supplies +5V and -5V, right? So the voltage between those terminals must be 10V?Sorry for the noob question, again!

author: wasedadoc
author_rank: Super Contributor
timestamp: December 19, 2022, 12:17:23 pm
content: Quote from: x_marx on December 19, 2022, 12:10:59 pmNo. Those are single voltage supplies. 5 Volts between the + and - terminals.

author: timenutgoblin
author_rank: Regular Contributor
timestamp: December 19, 2022, 12:26:36 pm
content: Quote from: x_marx on December 19, 2022, 11:52:34 amUse the wiring diagram that is given on the website.L N and earth is for the AC input.-V and +V is for DC output.

author: x_marx
author_rank: Contributor
timestamp: December 19, 2022, 12:36:30 pm
content: Thats what I did actually. I connected the -V terminal to the common (GND on the strip) and +V to the +V on the strip. I also connected the -V terminal with Pi's GND pin of its gpio and the system is working.I just wanted to see if it's meant to be this way or is there anything wrong with the psu.Sorry again!

author: Vovk_Z
author_rank: Super Contributor
timestamp: December 24, 2022, 07:42:30 am
content: Yes, thats's ok.
Powertool led/light feature resets - Page 1
Forum section: electronics / beginners

author: Erwin Ried
author_rank: Regular Contributor
timestamp: May 20, 2014, 10:59:14 pm
content: Hello, I have an electric jigsaw that has a laser/light. You can cycle the state in this sequence off, laser, led, both, off, (...) pressing a switch button but the thing is: sometimes while you are cutting it goes back to off.So, my first hint is this can be fixed with a cap to smooth the current the little uC (?) receives?The 2 white wires come directly from 220V, the red black 2 pairs go to the laser module and the led. I haven't removed the black silicone because it is quite hard and I may damage the circuit but these resistors probably are just for led/laser modules. The button is momentary. I am guessing an early design had another one due the button style.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: May 20, 2014, 11:17:45 pm
content: Well.. black stuff was easy to removeBTW the circuit is so simple! I would love to use this instead of USB-chargers in my atmega projects

author: SeanB
author_rank: Super Contributor
timestamp: May 21, 2014, 04:37:21 am
content: Check the little electrolytic cap to see if it has died, and if you can fit a slightly larger value in there as well. Add a VDR across the mains input, and solder a 10n chip capacitor across the pins if the push button switch ( the 2 pins that are soldered) and it should no longer change state from mains transients. just remember every part of this circuit is at mains voltage, no isolation at all, and nothing is connected to neutral other than a single wire and 2 diodes. Every output floats at mains voltage.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: May 21, 2014, 05:08:05 am
content: Thanks Sean, I am gonna check the cap, there is a little white thing in the other side of that cap, diode? no markings. What value you suggest? current one is 50V 22uFI don't have any VDR, any value you recommend?edit:my meter says the cap is spot on
PQ30RV21 - Page 1
Forum section: electronics / beginners

author: glinjik
author_rank: Regular Contributor
timestamp: February 16, 2022, 07:50:26 pm
content: Could some kind person explain this circuit for me, I was thinking of using it instead of a 317

author: Benta
author_rank: Super Contributor
timestamp: February 16, 2022, 07:55:49 pm
content: Why on earth would you want to use an obsolete, non-available part?

author: glinjik
author_rank: Regular Contributor
timestamp: February 16, 2022, 08:07:23 pm
content: Because i have a stack of them

author: golden_labels
author_rank: Super Contributor
timestamp: February 16, 2022, 10:39:25 pm
content: The first post is a bit confusing. You want to use them, but want an explanation for a test circuit. I will allow myself to auto-correct the question and assume that you are asking about application, not about building a test fixture for those regulators.What you want is on page 6 of thePQ30RV21 datasheet. The R2/R1 divider forms a negative feedback loop of the internal op-amp (pin 4) that controls output voltage (pin 2). If the voltage is too high, the op-amp throttles down the output transistor. Opposite if it’s too low. The idea is the same as with LM317, with the regulator trying to maintain voltage at the feedback pin at 1.25V.

author: Terry Bites
author_rank: Super Contributor
timestamp: February 18, 2022, 12:00:26 am
content: They look very handy to me- shutdown, foldback, what's not to love?
practical difference between SOD323 and SOD323F? - Page 1
Forum section: electronics / beginners

author: exe
author_rank: Unknown
timestamp: September 03, 2018, 07:27:22 am
content: Hello!I was buying some zeners and noticed that SOD packages generally come in two flavors: with and without 'F' suffix. The dimensions look virtually identical, the only difference I can spot is how leads are formed. On SOD323F they are straight, on regular SOD323 they are bent. I wonder why one would choose one option over another. Does one type of diodes provide more stress relief, better thermal contact, lower inductance and/or lower cost than another?Example pictures:- sod323:https://www.tme.eu/gb/details/udz6v8b-7/smd-zener-diodes/diodes-incorporated/- sod323f:https://www.tme.eu/gb/details/bzx84j-b6v8.115/smd-zener-diodes/nexperia/

author: exe
author_rank: Unknown
timestamp: September 03, 2018, 12:42:08 pm
content: I think I can answer my own questions. SOD323F has much lower thermal resistance. Presumably because leads are shorter.
Prank Chicken Screamer - Page 1
Forum section: electronics / beginners

author: funkybuttweasel
author_rank: Newbie
timestamp: June 10, 2025, 03:44:10 pm
content: Howdy guys. I'm currently working on making one of those rubber chicken screamer into an audible nightmare. I figure I can do this by removing the air activated plastic reed and replace it with a speaker, amp, USB soundboard, battery, and switch. I intend to internalize all components into the chicken and use the Aztec death wistle as the sound file of choice. I have a 20w, 4ohm, 5v barrel speaker that fits perfectly into the chicken's neck, and I'm asking if anyone has any recommendations as to which amp and board to purchase, and if it's even going to be sufficiently loud enough to startle a curious/nosey friend.Things I've made in the past have been really simple. I gifted a portable Hello Kitty mood lamp I picked up and modded from Goodwill to gift to my friend for Christmas. I had a broken $99 Milwaukee LED flashlight I gutted and installed into the mood lamp. She didn't like it at first, but I found out she keeps it in her car and uses it like a beacon when she does her Uber/Lyft. I also packed a butane torch into the casing of a Bic lighter because everyone kept stealing mine. I had to give some apologies and "now you effed up" for singed eyebrows. I'm not going anywhere with these anecdotes. ^_^

author: Zipdox
author_rank: Regular Contributor
timestamp: June 10, 2025, 05:04:13 pm
content: I suggest an I²S class D amplifier. You can then hook it up to a microcontroller with a large amount of integrated flash such as the ESP32 or Raspberry Pi Pico.

author: funkybuttweasel
author_rank: Newbie
timestamp: June 10, 2025, 05:26:37 pm
content: MY MAN! Everything adds up. Exactly what I was looking for. There were just so many options I didn't know where to start. Thank you. I ordered the parts and it only cost me about ~$30

author: jh15
author_rank: Frequent Contributor
timestamp: June 11, 2025, 02:20:10 am
content: Where do you get that chicken? I may need one for some Framework laptop support soon.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: June 11, 2025, 02:38:43 pm
content: Is there any chicken scream IC available?
PRBS(Pseudorandom binary sequence)  basic question - Page 1
Forum section: electronics / beginners

author: Wilfrid2000
author_rank: Newbie
timestamp: July 07, 2023, 02:16:28 am
content: I would like to ask a basic question, Figure 4.3 is a common serial PRBS, if you want to generate parallel PRBS such as Figure 4.4.But if you want to parallel 15-bit PRBS, why are not seen directly as shown in Figure 4.3 red line, pull out the output of each DFF, the same is m sequence, just a delay a clock

author: ataradov
author_rank: Super Contributor
timestamp: July 07, 2023, 02:34:33 am
content: You are answering your own question - those bits would not form a random sequence, it will be just a sequence of bit-shifted numbers.

author: Wilfrid2000
author_rank: Newbie
timestamp: July 07, 2023, 06:05:56 am
content: Thanks for your reply, but if I give each DFF output to a different channel in Figure 4.3, is this a random sequence for each channel?

author: ataradov
author_rank: Super Contributor
timestamp: July 07, 2023, 06:37:39 am
content: If you just take the output as you are describing, then you will get a sequence for the first 15 bits. But then to get the next 15, you need to wait for 15 cycles until all the old bits get flushed out.I assume the goal is to get the next N bits from the sequence without waiting for N clock cycles.Can you post what is in the Figure 4.4?

author: Wilfrid2000
author_rank: Newbie
timestamp: July 07, 2023, 07:58:36 am
content: Sorry, Figure 4.4 has been uploaded, I may not be clear in the description, I hope that as in Figure 1, each DFF output corresponds to a channel, for example, DFF1 output to channel 1 to generate PRBS, this is equivalent to each channel can receive PRBS.Like Figure 4.4 parallel 32-bit PRBS15 sequence generator circuit, which represents the desire to generate 32-bit PRBS in one cycle, and then convert it into a sequence by multiplexer to give a channel for testing?My goal is to give multiple channels, I wonder if the method in Figure 1 can be?

author: Andree Henkel
author_rank: Regular Contributor
timestamp: July 07, 2023, 08:25:00 am
content: There is no such thing as a "parallel PRBS".As PRBS means p* r* b* sequence, which means serial order.What exists are the serial and parallel topology to create PRBS, but that are basically just two different circuits to create the same serial order of pseudo random bits.What you can do is create several different PRBS of same length or of different lengths and output them in parallel.

author: ataradov
author_rank: Super Contributor
timestamp: July 07, 2023, 03:25:30 pm
content: Quote from: Wilfrid2000 on July 07, 2023, 07:58:36 amWith your proposal you will get N independent outputs that generate the same sequence shifted in time relative to each other. If this is enough for your testing, then it will work.The goal of the parallel circuit is to output N bits from the same sequence on each clock cycle.

author: Wilfrid2000
author_rank: Newbie
timestamp: July 08, 2023, 05:21:12 pm
content: Thank you both for your replies, I have understood!
Pre-biased transistor - Page 1
Forum section: electronics / beginners

author: MarkR42
author_rank: Regular Contributor
timestamp: October 20, 2020, 11:52:52 am
content: Hi,Yesterday I learned that pre-biased transistors are a thing.For example this one:https://lcsc.com/product-detail/Digital-Transistors_ON-Semiconductor-ON-MUN2212T1G_C274587.htmlSurely they are ideal for low-side switching of small loads from e.g. a microcontroller? It avoids the extra resistor(s).Has anyone tried them (or similar)? Did it work as expected?

author: Paul Rose
author_rank: Regular Contributor
timestamp: October 20, 2020, 06:59:44 pm
content: Quote from: MarkR42 on October 20, 2020, 11:52:52 amYep. That's what they're good for. Work fine.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 20, 2020, 07:12:34 pm
content: Quote from: MarkR42 on October 20, 2020, 11:52:52 amseems like more suitable for driver for the next stage's analog amplifier such as darlington or RF amp maybe. for direct driving load from mcu, n-mosfet such as AO3400 is better ymmv.

author: Paul Rose
author_rank: Regular Contributor
timestamp: October 20, 2020, 08:05:23 pm
content: I think the fact that the link and data sheet call them "digital transistors" is a hint at their anticipated use case. Though I agree that I might typically reach for a mosfet.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 20, 2020, 08:26:22 pm
content: The digital transistor compete with small MOSFETs, like 2N7002 , BSS138 and similar. They may be a little cheaper and lower ESD sensitivity and sill good enough to drive a LED. With a BJT the turn on level is also better defined than with MOSFETs. With a very low signal level this can be an issue.

author: Benta
author_rank: Super Contributor
timestamp: October 20, 2020, 08:59:04 pm
content: Logic-level MOSFET or BJT (in this case BRT, bias-resistor transistor) is a question of the application.Both have their uses.But in one area the BJT excels: C-E leakage current, which is practically negligible.Not so with the MOSFET, where D-S leakage current is significant, especially at higher ambient temperature.It's an engineering decision

author: S. Petrukhin
author_rank: Super Contributor
timestamp: October 21, 2020, 01:17:55 am
content: Like conventional transistors, they have their own characteristics. Their advantage is only in reducing the number of components, they are more convenient only. In the design, you need to study all their characteristics as a normal transistor. But you should pay attention that the resistors installed inside with ordinary digital signals introduce the transistor into deep saturation and this affects the speed characteristics.
Pre-cleaning boards before soldering - Page 1
Forum section: electronics / beginners

author: kalel
author_rank: Frequent Contributor
timestamp: November 18, 2017, 03:23:43 pm
content: I mostly do very simple THT soldering on protoboards or kit PCBs. Some videos suggest cleaning the copper on the kit boards before soldering, usually with a fiberglass brush.Is this an step to do in order to get better solder joints, and if so what tool do you recommend?

author: rhb
author_rank: Super Contributor
timestamp: November 18, 2017, 03:33:08 pm
content: I use hand dish detergent and a new green 3M brand scrubber. But fine (e.g. 240) grit sandpaper will do. You want a fresh bright copper surface. Generic green kitchen scrubbers from China don't have any abrasive and won't do a good job.Steel wool doesn't do a very good job and leaves little bits of metal around. Brushes are not very thorough.

author: AndyC_772
author_rank: Super Contributor
timestamp: November 18, 2017, 03:45:58 pm
content: I wouldn't try and scrub a PCB clean before soldering. The exposed copper should already be coated with gold, tin, or some other finish to protect it from oxidation, and unless the board is very old, it should solder just fine with a suitable flux.Plain copper stripboard is different, though. I usually give any stripboard a thorough clean with fine steel wool, which is way too abrasive to use on a PCB, but works well at removing the inevitable oxide layer that builds up on exposed copper.

author: kalel
author_rank: Frequent Contributor
timestamp: November 18, 2017, 03:49:32 pm
content: Quote from: AndyC_772 on November 18, 2017, 03:45:58 pmWith protoboards (those that have holes and copper around them) and stripboard you're right, there's only copper. But also on some kit PCBs there's only copper (edit: actually some are tin plated). Anyway I am mostly asking about the boards that do have copper exposed.

author: Arjen_Arg
author_rank: Contributor
timestamp: November 18, 2017, 04:22:51 pm
content: I agree with the others in that cleaning may do more harm than good. But, if you are working with cheap prototyping boards that don't have any finishing or solder mask, then, using steel wool will help remove rust and dirt.

author: rdl
author_rank: Super Contributor
timestamp: November 18, 2017, 06:34:33 pm
content: I don't know what's available where you live, but look for some mildly abrasive kitchen/bath cleanser. You might already have some. Here we have brands such as Ajax and Comet (and generic types also). Copper, when very clean and shiny, has a distinct pinkish color, and this type of cleanser will polish bare copper very well. Be sure to rinse well because there's bleach and stuff in the cleanser.
Pre regulator and Linear regulated power supply design Books - Page 1
Forum section: electronics / beginners

author: Gurumurthy
author_rank: Regular Contributor
timestamp: May 15, 2017, 05:29:15 pm
content: please give me some reference for practical design of Linear Regulated power Supply and Various Pre regulator circuit using SMPS Technique to deign my Lab power supply (rating 30V, 5 Ampere).

author: Simon
author_rank: Unknown
timestamp: May 15, 2017, 05:38:22 pm
content: DO NOT triple post the same topic! if you do YOU WILL be banned!
PreAmp Biasing Trimpot issue?  - Page 1
Forum section: electronics / beginners

author: lesabb
author_rank: Contributor
timestamp: February 29, 2016, 03:59:20 pm
content: I am newbie and trying to build the pre-amp section of the Neve 1073. I decided to bread board the BA283AM ONLY as per the attached schematics. I think there is a problem but i can’t seem to find it. The collector voltage on the 2N6248 is 20.6V. Shouldn't it be higher? When I turn the trimpot nothing happens. The Base voltage is ~10.6V and the E is at ~ 10V, which I think is OK but a bit higher than previously reported (~3V). Consequently, the C voltage of Q1 is at ~10.6V (much higher than the reported 3.6V). The transformer is connected to the 24V PSU and to the output of the BA283AM as per the schematics.Any troubleshooting ideas? ThanksLuc

author: Seekonk
author_rank: Super Contributor
timestamp: February 29, 2016, 05:30:36 pm
content: I don't see any bias turning Q1 on.

author: lesabb
author_rank: Contributor
timestamp: February 29, 2016, 06:04:20 pm
content: THis is what the whole thing is like.

author: Seekonk
author_rank: Super Contributor
timestamp: February 29, 2016, 08:25:32 pm
content: Obviously the output transistor it being turned on much, so the issue is in Q2&3. These should follow .6V drops. When you get enough voltage 47 ohm, Q1 will stabilize the circuit.

author: lesabb
author_rank: Contributor
timestamp: February 29, 2016, 10:02:58 pm
content: I don't know if I understand but the Q1 & Q2 Vbe is 0.6V drop

author: Seekonk
author_rank: Super Contributor
timestamp: February 29, 2016, 11:32:32 pm
content: Q2&3 are a simple darlington. Problem should be obvious from the voltages.

author: Andy Watson
author_rank: Super Contributor
timestamp: February 29, 2016, 11:46:00 pm
content: Quote from: lesabb on February 29, 2016, 03:59:20 pmEither the emitter resistor is not 1k2, or the collector resistor is not 68k - or possibly Q2 is dead or wrongly connected. 10V across 1k2 would require a current of 8.3 mA - so either the collector circuit of Q1 is wrong - too low resistance, or the emitter circuit has too much resistance.

author: lesabb
author_rank: Contributor
timestamp: March 01, 2016, 12:49:42 am
content: Thanks, I forgot that I was using MPSA06, not BC184C! Pinout is the opposite! HOWEVER now when i power up, the 47R smokes! I will go back and re-wire. My 47R is a 2W resistor.
preamp pentode and triode that can hold 700-800V - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: January 25, 2020, 04:20:51 pm
content: I want to use EL34 tube's here and power it at 1.6Kvbut those other triodes and pentodes, I don't know any that can hold that amount of anode voltage.also what tubes should I use here?[ Attachment Invalid Or Does Not Exist ]

author: Gyro
author_rank: Super Contributor
timestamp: January 25, 2020, 06:25:23 pm
content: Same subject ashttps://www.eevblog.com/forum/beginners/differential-gomes-amplifier-using-pentodes-in-ultra-linear-mode/

author: Gyro
author_rank: Super Contributor
timestamp: January 25, 2020, 07:24:39 pm
content: ... about the same circuit.

author: gbaddeley
author_rank: Regular Contributor
timestamp: January 28, 2020, 06:15:48 am
content: Build a smaller amp to prove that your design works, say 400 - 600 V, then scale up in a couple of increments
preamp/mixer or mixer for blending with passive guitar pickups - Page 1
Forum section: electronics / beginners

author: lathamuse
author_rank: Newbie
timestamp: September 03, 2015, 01:44:40 pm
content: HI, I'm trying to find the best way to mix passive humbucker pickups ( with coil splitting capability) with either a passive transducer or preamp electret mic, for a couple of Archtop guitars I'm building, I've been looking at theVelleman K1803, will it do the Job? I need to secrete the preamp and battery under the sratchplate my size limits are 17mm deep, 40x70mm L&B, I would ideally like as small a battery as possible, but if I must a9V is ok. Finally I need to have it wired up for a single mono guitar cable,,so I can plug straight into my amp. THe pickups each have their own volume and push push tone pots, ( coil splitting) and I hope to put the mixpot for the preamp through the scratchplate, the mic would go inside the body, any suggestions on mic choice would be greatly appreciated. Ive looked at the GFS EAP-100, and a schatten endpin mic preamp from stew mac, and some transducers from same sources. I'm a professional musician, so cost really matters to me, I'm trying to come up to speed on all this but there is a heck of a lot to learn!!, I just got a breadboard and parts to learn on so any pointers in that area would be gratefully received. the details of theK1803 are attached. I WOULD REALLY APPRECIATE ALL THE HELP I CAN GET, THANK YOU, I REALLY HOPE SOMEONE CAN HELP ME, Cheers, Paulhttp://www.vellemanusa.com/downloads/0/illustrated/illustrated_assembly_manual_k1803_rev2.pdf
Preamp/Xover cousing Turn off pop - Page 1
Forum section: electronics / beginners

author: Michaelaudio
author_rank: Regular Contributor
timestamp: February 12, 2021, 12:42:33 pm
content: So i build a BT speaker with a Selfmade preamp and 3 TPA3116 boards. 2x a stereo Board 1x Mono Board from eBay. When i Turn off Turn Off power, i have a Pop. When there is nothing connected to the amp boards, (or when i Turn the pot. to gnd) have no turn off pop. I know this is mit a good Design, and im already Wirkung in a new one, with Input buffer and a voltage follower for the biasing. It hast to be single supply since its battery powered.What i found Out: Amp Boards (stereo ones) have a shunt resistor in the Inputs (1k)When i turn the output of an op amp (uc1 Pin 8 dir example) its the exact same Pop Like ID Turn it Off. Yea i know that could damage the op but it was by accident.Value of the output caps doesnt seem to matter for the popSo ist it really my rather Bad design that causing the Pop?Boards:https://www.ebay.de/itm/173916201431https://www.ebay.de/itm/284035213328

author: Zero999
author_rank: Super Contributor
timestamp: February 12, 2021, 01:20:20 pm
content: Why create a new thread? What was wrong with the other one?https://www.eevblog.com/forum/projects/selfmade-preamp-noisey/

author: Michaelaudio
author_rank: Regular Contributor
timestamp: February 12, 2021, 02:22:55 pm
content: Nothing, just thought maybe id reach more people.
Precautions to be taken to implement a PWM dimming after a SEPIC converter ? - Page 1
Forum section: electronics / beginners

author: JL34
author_rank: Contributor
timestamp: November 29, 2020, 07:11:35 pm
content: Hello,I am looking to implement a PWM dimming between a SEPIC converter and a led string. What precautions have to be taken to make this ? Is there a simple and elegant way to do this ?SEPIC output would be 48V with frequency between hundreds Khz to few Mhz. Converter is not yet chosen.Led string current is 150mA.PWM dimming frequency should be above few Khz.Background :I am trying to design a modular led lighting with those elements :• A single power module with a SEPIC converter powering a 48VDC rail. With 12V-24V voltage input capability.• Multiple leds modules connected to the 48VDC rail.• Those led modules would have single or multiple led strings, with an OnSemi NSI (2pin Adjustable Constant Current Regulator) by string. I would like to add PWM dimming on those led modules.This way, i could achieve en-lighting with constant voltage driving advantages (adding leds modules easily) and constant current driving advantages (fine brightness control and stable current across temperature variation).Thanks in advance for your advice
Precise definition of CCM vs DCM (converters) - Page 1
Forum section: electronics / beginners

author: Mattjd
author_rank: Regular Contributor
timestamp: March 31, 2019, 03:47:49 am
content: Hi, I'm studying buck,boost, and buck boost converters and I am a little confused on the exact definition of CCM vs DCM.I have some plots for a buck,boost, and buck boost converter. I plotted the transient response for buck, boost, and buckboost. In the case of the buck boost converter and the boost converter there is a short time, before steady state is reached, that the current through the inductor goes below zero. I.e. it was zero for some instant of time. Now from what I've read, I believe that would mean DCM, despite having designed for a L>Lcrit which would be needed for CCM. Now at steady state, the current through the inductor for all 3 topologies is never zero.Is a more precise definition of CCM, that during steady state, the current through the inductor never reaches zero? DCM on the other hand, will have zero current at some point in time in steady state.
precision rectifier in thermostat circuit / understanding Hakko 936 circuit - Page 1
Forum section: electronics / beginners

author: JeanF
author_rank: Regular Contributor
timestamp: April 04, 2020, 07:18:50 pm
content: Hello,I try to learn by looking at simple circuits around me and spending some (usually large amount of) time figuring out how they work. Sometimes it gets a little bit tedious, I tend to get stuck! But I enjoy it, that's the main thing.In the Hakko 936 thermostat circuit, I get the basic principle of operation but I have a hard time with a few specific questions ; could anybody please help me with these ? Let's say that the opamps are named U1, U2, etc from left to right.- why are they using a precision rectifier (U3) to amplify the output voltage of U2 ? I can't see any situation where the output of U2 would go above 5.8 V. The input of the precision rectifier (left pin of R7) should be always less than the noninverting input of U3, so doesn't U3 behaves like an inverting amplifier at all times ? What am I missing here?- if I understand correctly, R9 is used to substract a constant value from U3's output, by reducing the current in R6 by a constant amount. What's the point of doing that?- I think R13 is here to give positive feedback/hysteresis for the internal comparator of the µPC1701 triac driver, is that correct ?Thank you!Credits (and thank you) to EEVBlog member "saturation" for the schematic.Notes:- VR2 is 0 to 300 ohms- Rsensor is around 40-50 ohms at room temperature (according to user manual) and can go up to around 140-150 ohms when hot (according tothis post)- µPC1701 datasheet is attached for anyone curious- partial (about one half of it) LTSpice schematic attached if anyone wants to play with component values
preparing / cleaning / deoxidizing copper electrical contacts?? - Page 1
Forum section: electronics / beginners

author: Robbie010
author_rank: Contributor
timestamp: February 11, 2019, 01:32:08 pm
content: Hello all,I am about to start putting my project amplifier back together and would like to clean and deoxidize the electrical contacts where possible. A number of the connectors are copper ring type connectors like the below image and I was going to give them a good cleaning and then scrub them with a gentle copper wire brush to remove any old oxidization and help improve the electrical contact.Is this advisable or would you deem it too abrasive?

author: graeme.c.payne
author_rank: Newbie
timestamp: February 11, 2019, 06:41:59 pm
content: If the ring terminals are plated like the ones in the picture (tin or nickel?) then they should not need much more than a quick wipe with alcohol. If they are bare copper then they probably do need cleaning. Clean copper looks like a bright new penny; oxidized looked like a penny that has been used for a few years.If you have or can find a good electronics contact cleaner, try that. If it needs scrubbing, then use a woven fabricc scrubber (ScotchBrite, for example), or a copper kitchen scouring ball.) You want it clean, with minimal scratches, and no foreign metals in it (like bits of a steel scouring pad. Wipe with a soft cloth, and the try not to touch the copper with bare fingers.If corrosion is Really bad, you could use fine grit garner sandpaper as a first step.Sent using Tapatalk
Prepositiononing a bldc sensorless motor - Page 1
Forum section: electronics / beginners

author: joelsrf
author_rank: Newbie
timestamp: October 24, 2022, 10:24:20 am
content: Hi there, I´m with some troubles controlling a bldc sensorless motor. I would like to know if anyone knows how to preposition de motor in order to start from a position that some magnets are aligned with the coils of the motor to execute the sequences perfectly.Thanks!

author: Benta
author_rank: Super Contributor
timestamp: October 24, 2022, 07:13:42 pm
content: If it's star connected (rare), power one phase and neutral with a DC pulse.If it's delta, pulse two phases with DC.Both ways will jerk the rotor to a steady position.
Press Fit pin headers - UK Supplier needed  - Page 1
Forum section: electronics / beginners

author: castingflame
author_rank: Regular Contributor
timestamp: April 20, 2020, 08:55:10 am
content: Hi allI am struggling to locate male Press Fit Pin headers from suppliers in the UK. They are the standard 2.54mm pitch and ideally they need to be 2 pin but obviously longer is okay as they can be cut.They are for a project where the end users may not be able to solder. I will be making a fitting jig to help the users fit them.Cheers.

author: jc101
author_rank: Frequent Contributor
timestamp: April 20, 2020, 09:01:32 am
content: I found Toby (https://www.toby.co.uk) to be very helpful.Their werbsite does list press-fit headers, though not in stock. It would be worth dropping them an e-mail or call, it's possible they have some just not on the website.

author: castingflame
author_rank: Regular Contributor
timestamp: April 21, 2020, 06:04:12 am
content: Quote from: jc101 on April 20, 2020, 09:01:32 amThanks for the suggestion. I have sent them an email.
Preventing differential follower loading? - Page 1
Forum section: electronics / beginners

author: s3c
author_rank: Contributor
timestamp: July 15, 2011, 02:56:18 pm
content: I'm trying to use a differential follower in a circuit to measure the voltage over a component, I eventually tracked down the bug and was able to reproduce it using the following circuit (note the simulation works fine, it's the real world circuit that doesn't):Now with only these components hooked up it works well enough until the Setable point drops below 0.6V, when this happens the output of U2 remains at 0.6V even though the + pin of U2 is below -. The kick is that when I unhook the follower from the differential amp it starts following normally and can reach to ground, I haven't tried it with another op amp yet but I'm still curious as to why this is happening.When I remove the buffer the circuit works but the differential amp pushes the voltage at this point up slightly in a nonlinear way so the readings aren't accurate. Any ideas?

author: toli
author_rank: Frequent Contributor
timestamp: July 16, 2011, 06:05:36 am
content: How much current does it have to sink?Just like the LM324, it can only sink about 50uA before the output jumps to around 0.6V.

author: s3c
author_rank: Contributor
timestamp: July 16, 2011, 12:17:04 pm
content: Jip, that did it, thanks toli. I didn't even know to look for these specs. I'm slowly realizing that college courses don't focus nearly enough on practical aspects and that spice models aren't what they're made up to be.

author: toli
author_rank: Frequent Contributor
timestamp: July 16, 2011, 01:06:14 pm
content: I'm still a student myselfIts just that I've had a very good professor who was in charge of the Analog Circuit course which was focused mainly on feedback networks and op-amp circuits.

author: s3c
author_rank: Contributor
timestamp: July 16, 2011, 11:01:48 pm
content: Just read chapter four of Art of electronics to gain some insight about nonideal op amp behaviour, it mentions the lm358 by name and why it behaves in this manner, anyway...

author: tecman
author_rank: Frequent Contributor
timestamp: July 17, 2011, 12:43:51 am
content: If you need to go closer to the bottom rail, and not so critical about the high side, you can load the output to V- with a resistor. This can pull the output lower as you are sinking some percentage of the current.paul

author: s3c
author_rank: Contributor
timestamp: July 17, 2011, 06:04:45 am
content: Thanks techman, I got it working but could you give an example of this perhaps since I've read about it somewhere but haven't seen it?
Preventing display damage due to over-volting - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: October 23, 2019, 10:20:58 am
content: HiI have bought a couple of these displays (https://www.aliexpress.com/item/32949282762.html?spm=a2g0s.9042311.0.0.14ed4c4dKHemnJ) as used here in a project -https://twitter.com/chrishutchinson/status/1136743837244768257One of the reviews on AliExpress states 'But be careful-on the module the power io is supplied from 1.8 v regulator, which means the input of the data bus can not be higher (i approve on the basis of my sad experience-the previous same display i burned, by connecting directly to esp32 conclusions)' but the guy doing the project seems to have connected his display straight to the Pi.There's the same project here but with a slightly different display that is also connected directly -https://www.balena.io/blog/build-a-raspberry-pi-powered-train-station-oled-sign-for-your-desk/Display controller info here -https://www.newhavendisplay.com/app_notes/SSD1322.pdfDo I need to use level shifters or was the review comment wrong ?Thanks

author: tooki
author_rank: Super Contributor
timestamp: October 23, 2019, 01:35:46 pm
content: I think the commenter is wrong. The datasheet says that the data lines can't be higher than the low-power (logic) power input. But the datasheet also says that said low power input needs 2.4-3.5V. It's highly unlikely that the display module is putting 1.8V onto the power input, well below spec.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: October 25, 2019, 11:50:42 am
content: Quote from: tooki on October 23, 2019, 01:35:46 pmThanks for the reply. Please would you be able to elaborate ?

author: tooki
author_rank: Super Contributor
timestamp: October 25, 2019, 02:53:53 pm
content: Just to recap, the datasheet says that the maximum voltage on an input is the same as the low-power supply voltage. E.g if you’re running it on 3.3V, then you can apply up to 3.3V on an input, but if you’re running it on 3.0V, then you can’t apply more than 3.0V on an input.The commenter said the module uses a supply voltage of 1.8V. But the datasheet says the IC needs 2.4V minimum to operate. So either the commenter is wrong, or the commenter had a faulty module, or the commenter was using too low an input voltage to the module (such that the regulator can’t regulate properly, or the module (for some inexplicable reason) is under powering the chip on purpose.My guess would be that the commenter is wrong.
Price of Silicon Labs BGX13S/P has changed from $4 to $10 - Page 1
Forum section: electronics / beginners

author: Day101
author_rank: Contributor
timestamp: February 27, 2019, 05:09:10 am
content: Hi,I'm trying to make a small device that uses bluetooth to talk to android or apple phones and tablets. I found the Bluetooth express BGX13 from Silicone Labs which looked like a simple way to avoid a lot of bluetooth connectivity development effort. I now wonder if it's being phased out because the prices seem to have doubled.When I first looked at prices I sawhttps://www.prnewswire.com/news-releases/silicon-labs-wireless-xpress-modules-deliver-bluetooth-and-wi-fi-connectivity-with-zero-programming-300712568.htmlwhich says prices are as low as $4.09 for 10,000but now I see octopart listing prices around 10 dollars and I wonder what might have caused this.https://octopart.com/search?q=BGX13Now that I reread the prnewswire.com page I wonder if they meant the Wireless express module/sip instead of the bluetooth express versionAnyone know whats the reason?Also is there an alternative module/SIP with a good/easy bluetooth setup and easy connectivity with low developer effort? I dont want to spend weeks debugging bluetooth bugs on 101 phones and I think something like BGX13 offers a way to avoid that. I don't need bluetooth 5 range/bandwidth. I origianlly got nrf52840 dev stuff but switched to silabs when I realised it offered an easier development route.Thanks,-Jason

author: Wolfram
author_rank: Frequent Contributor
timestamp: February 27, 2019, 10:04:15 am
content: The press release seems to have been written by SiLabs, so the pricing listed would be the pricing directly from the manufacturer. Octopart lists the pricing from distributors, which includes markup.

author: Day101
author_rank: Contributor
timestamp: February 27, 2019, 06:13:45 pm
content: Interesting. Thanks. When I look on the Silicon Labs site they do have a Buy button but the page it takes me to says "Powered by Mouser" and it will only checkout some items.I could add the Bluetooth development board but I couldn't add a BGX13S. It saidQuote

author: coppice
author_rank: Super Contributor
timestamp: February 27, 2019, 06:36:51 pm
content: The press release says the AMW007 and AMW037 modules (not the chip) will be $4.09 in 10k quantities.https://eu.mouser.com/ProductDetail/Silicon-Labs/AMW007?qs=rN85NNvew%2FQDVI%252bIVpqIHw%3D%3Donly shows pricing up to 500 parts, but its already down to 5 Euros at 500. By 10k its probably down to around $4, but you would need to contact them directly to find out.
Primary/secondary voltage regulation  - Page 1
Forum section: electronics / beginners

author: garethw
author_rank: Regular Contributor
timestamp: July 29, 2019, 07:26:18 pm
content: Reading the data sheet of an STM32F0 reveals they have the option of supplying the analogue peripherals with a separate power supply. This got me thinking about the power supply requirements for my current project.My question is this, is it common to use a switched mode power supply to step an input voltage down and then drop the final voltage with a low noise LDO? I’m thinking of stepping down an input voltage from 6-12V down to 5v and then to 3.3 using a couple of LDOs to prevent too much heat as I’m measuring temperatures amongst other things.Sent from my iPhone using Tapatalk

author: MosherIV
author_rank: Super Contributor
timestamp: July 29, 2019, 07:48:14 pm
content: QuoteLDOs do the same job as regular Voltage Regulators, convert excess voltage into heat.The advantage of LDOs is that they can be used with a lower input voltage for regulation.Yes, it is common to use switching regulators followed by Vregs to create multiple voltage rails.It can also be done with multiple switching regulators as well (more efficient if it does not mind the noise)Vregs are not a good choice when battery powered.If powered via mains psu and heat can be managed, Vregs can be ok and easier to use than switching regulatorsMicros do not mind too much if you feed them with noisy power rail.ST, like many chip makers, provide for a seperate power supply section for noise sensative parts of the chip, eg ADCs or DACs

author: garethw
author_rank: Regular Contributor
timestamp: July 29, 2019, 08:30:56 pm
content: Quote from: MosherIV on July 29, 2019, 07:48:14 pmI am aware that an LDO is a conventional linear voltage regulator. What I meant was that stepping down the voltage with a SMPS produces less heat than doing so by the LDO alone.
Primer on PSU design? - Page 1
Forum section: electronics / beginners

author: Sigmoid
author_rank: Frequent Contributor
timestamp: March 26, 2014, 02:25:56 pm
content: Hey guys,What resources should I read / research before designing a linear PSU from scratch? I read what I could on transformers and regulators, but I'm wondering about best practices, safety, overvoltage and overcurrent protection, and generally about designing a PCB for 120/240VAC.

author: Rigby
author_rank: Super Contributor
timestamp: March 26, 2014, 03:52:51 pm
content: Older HP supplies like the 6286A haveEXCELLENT manuals descriptions on the theory of operation and complete schematics. They don't use custom parts, just transistors, transformers, resistors, caps, diodes and switches. And a panel meter, which I guess probably would be custom if you bought it today.I would start there and learn what can be learned. Pretty much the entire theory of operation is written in those manuals.

author: Shock
author_rank: Super Contributor
timestamp: March 26, 2014, 07:05:35 pm
content: Dave has a primer on designin his PDF here.This is on hisAlternate Zone websiteObviously there is a ton of books on it as well.It's not at all unusual to keep the primary side of the circuit totally off the main PCB.You will need to read up on all the safety aspects. Studying well made equipment can be a good way to learn as well.I think if I was going to build one without following a book, magazine or kit I would do it in stages getting a basic prototype working first and then add the features.There comes a point where you might want to simulate your circuit before you add further features to the prototype as well.Here is a good video (if you haven't seen it) with some basic protection on the regulator. I apologize if your past this point.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: March 26, 2014, 08:49:03 pm
content: All of Jim Williams, basically:http://www.linear.com/designtools/app_notes.php

author: dentaku
author_rank: Frequent Contributor
timestamp: March 27, 2014, 12:55:19 am
content: Quote from: AcHmed99 on March 26, 2014, 11:50:31 pmGood stuff. I just downloaded Linear & Switching Voltage Regulator Handbook.