hybridfree/eevblog-posts huggingface dataset:
Audio Amp Load - Page 1
Forum section: electronics / projects

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: December 03, 2010, 06:50:26 pm
content: Anyone know of any reasons this would NOT be a good dummy load for a 35W audio amp?http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=RHRD-8.0-ND

author: Balaur
author_rank: Unknown
timestamp: December 03, 2010, 07:24:23 pm
content: That's a good choice. There are no reasons not to use it.One could object that a loudspeaker has a complex impedance (resistive, inductive and even capacitive components) and it's also nonlinear (inductance, phase varying with frequency, etc).However, using a resistor it's an accepted practice. In any case, the amplifier characteristics and performances are usually specified using a resistive load.Also, a quick comment on using resistors that will have to dissipate a lot of power: the temperature coefficient is very important since it could modify the resistance for different output powers. However, in your case, the tempco is only 50ppm, which is perfectly usable.Cheers

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: December 03, 2010, 08:08:00 pm
content: Thanks Balaur.The datasheet specifies a pretty hefty heat sink to hold that 50ppm spec. (291 sq in surface area).What I also learned from the datasheet and hadn't thought of before (although it makes perfect sense) is that you have to HUGELY derate this resistor if you run it without a heat sink. This is a 50W resistor, but without a heatsink you can only run it at 20W.Luckily I have a beefy heat sink, and I'll probably add a small fan to it.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 03, 2010, 10:41:35 pm
content: Just use a coil of nichrome wire at the length needed to get the impedance you want. Very high power rating and very cheap.

author: Zad
author_rank: Super Contributor
timestamp: December 03, 2010, 11:32:25 pm
content: If it is relatively low power, use a 20W (or whatever) car lamp. NOT a halogen one, their 'cold' resistance is incredibly low.

author: Zero999
author_rank: Super Contributor
timestamp: December 04, 2010, 02:13:52 pm
content: Any filament lamp will have a low cold resistance, halogens might be the worst but it's also true for standard incandescent.Has anyone blown a resistor like that? I've found they explode, the ends pop out.It's true that real speakers aren't purely resistive so the only way to really test it is to use a speaker, compete with crossover and enclosure but a resistor is fine for most applications.

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: December 04, 2010, 03:46:49 pm
content: I'll do the regular bench testing using a pair of real speakers but I want to do a long burn-in of the amp under full power, thus the need for a dummy load.
Audio Amplifier Application Schematic - Page 1
Forum section: electronics / projects

author: eerocketman
author_rank: Contributor
timestamp: April 15, 2019, 01:23:38 am
content: Hi Everyone,I am making a bluetooth speaker using the the LM2976 (http://www.ti.com/lit/ds/symlink/lm2876.pdf). the typical aplication schematic is pretty straight forward except for a BJT connected to the power leads of the IC. Could someone explain what the purpose of the BJT is? I have highlighted the component in question on the attached image.Thanks!!

author: Circlotron
author_rank: Super Contributor
timestamp: April 15, 2019, 01:27:35 am
content: With split pos and neg supply rails pin 7 is normally grounded i.e. halfway between pos and neg. With a single supply rail setup like in this diagram the BJT supplies pin 7 with approx half rail voltage.

author: eerocketman
author_rank: Contributor
timestamp: April 15, 2019, 01:32:30 am
content: Got it, thank you!

author: coromonadalix
author_rank: Super Contributor
timestamp: April 15, 2019, 01:32:53 am
content: the 2n3904 is not an bjt, its an npn transistor

author: eerocketman
author_rank: Contributor
timestamp: April 15, 2019, 01:35:30 am
content: Could you elaborate on the difference? I thought NPN transistors were BJTs.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 15, 2019, 02:46:12 am
content: sorry its bipolar junction transistor indeed my badmixed with an ujt loll

author: Audioguru
author_rank: Super Contributor
timestamp: April 15, 2019, 03:27:26 pm
content: What speaker impedance and power supply voltage are you using for the LM2876 amplifier IC?
Audio Amplifier Board - Page 1
Forum section: electronics / projects

author: MrAureliusR
author_rank: Unknown
timestamp: September 16, 2013, 12:51:11 am
content: While I was in Toronto recently visiting family, I hit up the local electronics stores as the city I live in has nothing even close to the variety they have. I went to Active Surplus and Creatron, and had a blast! Active Surplus is amazing. They've got just about anything you could ever possibly want, and they're cheap! As the name suggests, they buy surplus electronics and resell them. Of course they've got basic components, in bulk, for super cheap -- but then they end up with weird boards that they can't identify, or they have some info but not enough to really know what to do with something. So they throw them all in a bin marked $1 or 50 cents.Well I picked up one, labelled "Audio Amplifier - $1". I've been meaning to try and build a preamplifier so I can plug my turntable into a regular input on my receiver. I'm not sure if this one will do the trick or not (I'm leaning towards not) but I still can't figure out much of what's going on.I've been able to identify the SIP package: it's anNEC uPC1032H. I've been trying to reverse-engineer the board based on the pins from that package but I'm not getting far as I don't know enough about amplifier circuits.I've attached pictures, and as I've noted the pads on each end are labelled C, O, M, and L respectively. (I apologize, my stupid camera phone can't focus for crap) I've had a hard time figuring out what each could mean. I can tell that each set of pads at either end of the L shape are separate inputs and outputs, i.e. they contain both the I/O for one audio channel. I've tried to trace the output of each channel on the SIP back to a pad, but it's difficult as everything is so close together. C and O have a cap connecting them, and the C pad is only connected to the negative lead of that cap, and nothing else, which was intriguing.Any light that could be shed on this would be amazing! I've hooked up +5V to it and nothing explodes, which is a good sign. But obviously it doesn't draw anything (not much anyway) because I haven't figured out how to hook something up to it. I'm happy to prod, poke, measure and solder if need be. I'm very curious and I'd love to get it doing something. I really should have grabbed a few so I could sacrifice one if need be to figure them out.

author: kizzap
author_rank: Unknown
timestamp: September 16, 2013, 04:11:19 am
content: according to the datasheet, the outputs for the amplifier are pins 3 and 6, trace these out to capacitors which get connected to any of the connectors you see and you will have your outputs.The inputs should also be connected by a capacitor, which will be connected to a resistor network to bias the amplifier at +Vcc/2.One of those Labels on the end connectors should be common too.I am not certain on this, but I think each side is one amplifier, as in, signal doesn't travel from one side to the other.At an extreme guess, C = Common, O = Output, M = Mic? and L = Line.-kizzap
audio amplifier build - two channel chipamp  - Page 1
Forum section: electronics / projects

author: JustSquareEnough
author_rank: Unknown
timestamp: May 21, 2018, 05:55:54 am
content: This will be the first in a long line of posts (in this one thread) as I learn about and build my first audio amplifier. I'll be using an IC based amplifier, more than likely the lm1875. As a first step I spent some time understanding the lm1875 datasheet and built up a single channel prototype based on the datasheet application circuit. It was a lot of fun and I learned a lot about the surrounding components.attached are a few pictures of the prototype build up. I wont be using this brown prototypeing board anymore, its is absolute garbage!!I also put together a video exploring the datasheet and doing a listening test of the prototype.I hope you guys follow along with me as I build what will hopefully be my first "completed" electronics project.-DavidP.S. I've learned a lot by watching JohnAudioTech on youtube and reading Rod Elliott's site (sound.whsites.net)http://davidharms.me/Electronics/ExloringTheLM1875AudioAmplifierPart1
Linear power amplifier configuration - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: June 10, 2020, 04:56:36 pm
content: Hi,I have an audio input signal coming in from either a signal generator or a line-level audio source (MP3 player etc). It then needs to be sometimes amplified and sometimes attenuated. The output then needs to be able to drive various transducers: sometimes speakers and sometimes custom linear actuators (inductive types).I only have single supply on the PCB so I came up with the attached schematic.The output sometimes needs to be AC coupled and sometimes it needs to ride on top of a DC offset that is half of the supply voltage. That is the reason for the jumper at the output.Is that a good way to do it?Thank you
Audio Amplifier Selection - Page 1
Forum section: electronics / projects

author: joersam24
author_rank: Contributor
timestamp: May 22, 2012, 02:11:26 am
content: Hi to all,I want to amplify an audio signal from the output of CODEC with a minimum line out resistance of 2k? and the output of the amplifier will feed to a dynamic receiver(earpiece) with an impedance of 150?. Can anyone suggests a suitable audio amplifier to be used? What should be the implementation? Do I need some impedance matching device?I hope you can help me with this one. Thank you...

author: Zero999
author_rank: Super Contributor
timestamp: May 24, 2012, 09:09:26 am
content: The LM386 will probably do but you haven't mentioned the input/output levels.

author: FenderBender
author_rank: Super Contributor
timestamp: May 28, 2012, 12:26:28 am
content: Not exactly sure but a low noise op-amp would probably do.TL071, NE5532 or OPA2314. A 150ohm headphone shouldn't take too much to drive.LM386 would also work. THD figures might be a little higher?

author: T4P
author_rank: Super Contributor
timestamp: May 28, 2012, 02:37:19 am
content: 150ohms is not a hard one to drive,do you want a 1W headphone driver or you want a normal opamp ?The NE5532 can drive down to 15 ohms load i think but it does have 38mA output short-circuited nominallyOR you can just shoot for a 1W headphone driver that is available only in weird packages but most phones use that

author: ejeffrey
author_rank: Super Contributor
timestamp: May 28, 2012, 03:41:27 pm
content: There are many options for headphone amplifiers, from dedicated chips to opamps to discrete transistors. All are capable of performing admirably. One question was unaddressed:QuoteNo, impedance matching is generally undesirable in audio applications. The major exception is the analog phone system. In general you want the output impedance much less than the input impedance it is driving. So your amplifier should have an input impedance much greater than 2.2 kohm and an output impedance of much less than 150 ohm. This is not hard to accomplish, just something you need to be aware of.Is this a line-out from some existing equipment, or are you implementing the codec yourself? If the latter, you will need some anti-aliasing filter. The data sheet for the CODEC will help you out.

author: FenderBender
author_rank: Super Contributor
timestamp: May 28, 2012, 04:26:37 pm
content: A popular project is a "cMoy" that you can look at for reference. It's just a non-inverting op-amp set up but there's loads of information on it. Some valuable, some audiophoolery. Either way. Might want to give it a glance.

author: T4P
author_rank: Super Contributor
timestamp: May 28, 2012, 04:31:12 pm
content: Quote from: FenderBender on May 28, 2012, 04:26:37 pmYes but it uses audiophoolery-ish pricey parts like the Burr-brown OPA2134

author: FenderBender
author_rank: Super Contributor
timestamp: May 29, 2012, 03:14:38 am
content: True,any modern op amp would work

author: joersam24
author_rank: Contributor
timestamp: May 31, 2012, 12:50:08 am
content: Thank you everyone for your replies and suggestions... It really helps me as I'm a beginner in Electronics Design...
Audio codec AIC3106 and performance - Page 1
Forum section: electronics / projects

author: rakeshm55
author_rank: Regular Contributor
timestamp: February 10, 2019, 06:07:17 am
content: Hi all,I wanted to use TLV320AIC3106 in one of our design. So procured an evaluation board of the same.http://www.ti.com/tool/TLV320AIC3106EVM-KI will be attaching a coil mic to it. On testing the mic i could acquire Vpp in the range of 2mV to 10mV.I was trying to capture audio samples using AIC3106evm. I fed to mic input using audio analyzer(600Ohms,1Khz tone,sine ).I acquired samples (sound recorder in Windows 7) using PC in .wav format.following were my configurations for codec to capture inputMIC3R input on audio codec (LADC)Level (attenuation set to 0db)PGA set to 0dband fed following range (3mV to 500mV) 1kHz tones.On analyzing the captured input ....I can receive 50mV (wave shape maintained) ..... below 50mV inputs waveshape looks unrecognizable ....Applying 500mV gives a clear swing, for lower voltages (below 50mV) no much negative swing seen....I tried applying PGA of 20dB to lower voltages 3mV to 50mV here to lower voltages though receive higher amplitude has no tone content for voltages below 50mV.I am unable to identify what is the issue. Is this noise inherent at chip input?? is it board induced noise overcoming weak input signals.??I later modified the input with low pass filter of 4kHz bandwidth but of no use.Does it mean I need to amplify the signal before sending to codec??
Audio DAC distortion/error cancellation  (ESS9038) - Page 1
Forum section: electronics / projects

author: hellokitten
author_rank: Newbie
timestamp: April 01, 2018, 04:09:10 am
content: I want to build a high end DIY audio dac and I'm planning on buying a 9038 Buffalo dac kit but I have some questions.First off, a bit unrelated to my main question, I can't seem to find a straight answer to this. The stereo current capability of the 9038 is 60ma per channel right?Secondly I have a question about the optimal way to configure the stereo output.The two options being splitting the 8 channels into 4 parallel dacs per channel or splitting the 8 channels into 2 parallel differential outputs per channel.Here is a quote I foundQuoteSo this makes me wonder, does the es9038 function as "true balanced" as he describes it or is it internally SE?Is it better to simply sum 4 dacs together per channel or to go full differential and feed it into a differential amplifier for common mode distortion cancellation?If the internal process is SE then would it be worth it to use separate dacs as he describes? It would seem that in theory it would allow for perfect performance of the dac.As far as using separate dacs goes here is a couple of quotes from the Buffalo kit creatorQuoteQuoteThe first quote states that sending the signal to both dacs is challenging, but in my proposed scenario it would not be dual mono but dual stereo with a phase flipper being used to feed one of the dacs. Is there some hidden trouble in this I don't know about?For the second quote he says he needs to lower the master trim which reduces dynamic range and THD, but is this THD related to the distortion we are cancelling out in my proposed method anyway?Sorry for all the questions, I've got a lot invested into this already and I've had a difficult time finding an answer to this.
Audio DAC vs. general purpose DAC (or ADC for that matter) - Page 1
Forum section: electronics / projects

author: chrome
author_rank: Regular Contributor
timestamp: June 24, 2012, 01:34:58 pm
content: So as the title says, what is the difference between the two? Seeing as there are huge price gaps between the 2 kinds.

author: joelby
author_rank: Frequent Contributor
timestamp: June 24, 2012, 01:55:26 pm
content: DC accuracy comes to mind. This looks like a good article on the topic:http://electronicdesign.com/article/analog-and-mixed-signal/should-you-use-audio-adcs-for-precision-applications-

author: Quiggers
author_rank: Contributor
timestamp: June 24, 2012, 02:14:27 pm
content: sample rates, audio is quite slow compared to most data busses, even an 192kHz Codec will often have anti aliasing filters set at 22kHz, limiting the bandwidth you can capture. An as said above, most have DC blocking caps, look for "DC coupled" if you do not want a codec with an integrated capacitor.Really it comes down to what type of signal you want to acquire.

author: jahonen
author_rank: Super Contributor
timestamp: June 24, 2012, 04:45:18 pm
content: I think that the low-pass scales with the sampling frequency. At least on PCM1792A datasheet:Regards,Janne
Audio distribution amp. - Page 1
Forum section: electronics / projects

author: SNGLinks
author_rank: Regular Contributor
timestamp: October 19, 2019, 01:51:34 pm
content: HiI have an stereo audio switch unit. I wish to feed this to, up to, 5 stereo domestic amplifiers.Instead of just paralleling the inputs I want to build a distribution amplifier. I was thinking of using two power amplifiers such as an LM380 and feeding each amp input via a series resistor.What do you think of the idea and what value resistor is required?

author: Audioguru again
author_rank: Regular Contributor
timestamp: October 19, 2019, 05:03:28 pm
content: Why use an LM380 POWER amplifier when the inputs of five domestic audio amplifiers use almost NO power? The LM380 is not hifi.Instead us a simple audio opamp as a distribution amplifier that will have a high input resistance and an output that can drive hundreds of domestic audio amplifiers. A dual audio opamp like a stereo OPA2134 has extremely low noise and distortion.

author: SNGLinks
author_rank: Regular Contributor
timestamp: October 19, 2019, 05:31:25 pm
content: Thanks for your reply. I have loads of TL072s so could use that. What value resistor should I use? I want some isolation between outputs so a short on one line cannot effect another.

author: DaJMasta
author_rank: Super Contributor
timestamp: October 19, 2019, 05:39:01 pm
content: Any good audio opamp should be able to be configured as a follower amp so you can drive however many lines from a single source (a follower amp driving each) without any gain.If you want over-current protection, you just need to look at the output spec of your chosen opamp and add a series resistor that keeps the full scale output below that current - probably on the order of 50-100 ohms, depending. If you're talking about ground isolation to eliminate added hum, you're going to need transformer coupling or some similar method - much more complicated and harder to get right, especially if your device has its own power supply, and may be less of an issue with your own installation.The devices you are running are high impedance (high resistance even to AC signals like sound waves), so in normal operation, the opamp will drive very little power through the load to maintain signal levels. You only need amplifier ICs for very high voltages or, more commonly, low impedance drives (like an 8 Ohm or less speaker), a line level input is designed not to need much power to be properly driven.

author: awallin
author_rank: Frequent Contributor
timestamp: October 19, 2019, 05:39:47 pm
content: one op-amp per output, if you want some isolation.see e.g.https://electronics.stackexchange.com/questions/266872/active-audio-splitter-line-levels
Audio Distribution Amplifier - Page 1
Forum section: electronics / projects

author: German_EE
author_rank: Super Contributor
timestamp: July 12, 2015, 11:47:29 am
content: I want to build this circuit but with two inputs rather than one:http://www.seekic.com/circuit_diagram/Amplifier_Circuit/AUDIO_DISTRIBUTION_AMPLIFIER.htmlWhat bothers me about this design is the direct connection between an opamp output and the three non-inverting inputs. What will happen when I connect two opamp outputs and three inputs together?

author: SeanB
author_rank: Super Contributor
timestamp: July 12, 2015, 12:06:33 pm
content: Put a 10k resistor after the feedback point on the first opamp (R2), and simply duplicate the input again with the added resistor, and connect the resistors to the 3 opamp inputs you are using. You can also share the R4, R5 bias network but reduce the resistors to 10k, and leave C2 at 100uF.Otherwise, just common the inputs with 10k series resistors and you will be fine.

author: German_EE
author_rank: Super Contributor
timestamp: July 12, 2015, 02:34:30 pm
content: OK, thanks, in my head I tried to image one opamp at +9v output and the second at -9v, the results were not pretty and those series resistors fix the problem.

author: Mark Hennessy
author_rank: Frequent Contributor
timestamp: July 12, 2015, 07:10:19 pm
content: It would also be wise to add series resistors for each output. Something like 47 or 51 ohms would be enough. Otherwise, the op-amp might be unhappy at having to directly drive the capacitive load presented by the cables.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 12, 2015, 08:06:29 pm
content: The differential input range is fine, even if the output is shorted and the first amp is driving full scale.TL082 isn't much of a driver, you may want something with higher output current. And then, add a series output resistor (maybe 100 ohms, so the output doesn't directly drive line impedance, which might be capacitive or worse), and for perfect LF/DC fidelity, you can also add a feedback loop: cap from OUT to -IN (maybe 100pF), resistor from -IN to line connector (maybe 1-10k).A common sight for DC accuracy is using equal series resistance (or Thevenin equivalent) to the input terminals, but since TL082 is a JFET type, its input bias current is low enough to ignore. This is a useful tip for best DC offset on bipolar types (e.g. LM833?).Tim
Audio embedding / de-embedding - Page 1
Forum section: electronics / projects

author: mrpackethead
author_rank: Super Contributor
timestamp: August 22, 2018, 09:24:58 am
content: I'm wondering if any one has seen any schematics / applicaiton notes, for embedding and de-embedding Audio on SDI Video?I have an applicqaiton where i want to pull the audio out well before it gets to the video processing. I also need to be able to inject it backin.

author: dmills
author_rank: Super Contributor
timestamp: August 22, 2018, 10:58:19 am
content: The usual approach is an FPGA with at least one transceiver to do the embed/deembed and an LMH something or other to act as line equaliser and driver, but IIRC Genem/Semtech had a part that specifically did audio embed/deembed but it will be ancient by now, might be worth asking about it still.I would have thought that a very modest Artix 7 would get it done with no fuss, we use the -35s but we also do video and scaling in there, so something smaller may well work for you.Regards, Dan.

author: mrpackethead
author_rank: Super Contributor
timestamp: August 22, 2018, 10:10:29 pm
content: Thanks.. Thats a good place to look. Semtech appear to have a few useful chipsets!
Audio ground loop isolator - Page 1
Forum section: electronics / projects

author: 0b01010011
author_rank: Regular Contributor
timestamp: December 19, 2016, 09:54:45 am
content: So I have a car that doesn't have bluetooth but does have an auxilliary input. So just use a headphone to RCA cable and all will be fine.... well fine until you want to charge the phone from the car charger. I don't know if it's particularly a problem with my model of car (Lancer CJ), but this causes a whine that goes higher and louder with the engine revs.I recognised this as a ground loop issue but of course didn't want to spend money fixing it. So I was looking at my collection of random boards, and found a PSU board from an old Sony BVM that had 2 common mode chokes, both identical. Essentially they are just transformers and there were 2 identical ones.So I hooked one to my signal generator and scope and the response is suprisingly flat from the low 10's of Hz up to at least 100kHz.I wired them up to some connectors and tried it out and it works no problem!

author: wraper
author_rank: Unknown
timestamp: December 19, 2016, 10:13:21 am
content: Dunno if this is good solution for sound, you won't see distortions on the scope, unless they are like >5%. Although with crappy car speakers and road noise might be fine. I would isolate charging side, not audio.

author: 0b01010011
author_rank: Regular Contributor
timestamp: December 19, 2016, 10:23:58 am
content: Supply side isolation would be more of a possibility for just a bluetooth receiver such as this Sony 'knob' I am thinking of buying...http://www.sony.com/electronics/in-car-receivers-players-accessories/rm-x7btI doubt this thing draws more than 50-100mA so one of those SIL package isolated DC-DC converters should work for this. Might try that. Much smaller than this solution anyway.

author: tszaboo
author_rank: Super Contributor
timestamp: December 19, 2016, 01:42:14 pm
content: Isolating power is probably simpler than isolating audio. Just sayin.

author: GreggD
author_rank: Regular Contributor
timestamp: December 19, 2016, 04:04:52 pm
content: You can isolate audio with a 300-ohm modem transformer. Works fine connecting one pc audio to another pc.
Audio Jack Connector - Which pin is L-/R-Channel / GND? - Page 1
Forum section: electronics / projects

author: soFPG
author_rank: Frequent Contributor
timestamp: May 23, 2021, 06:17:51 pm
content: I wanted to used this audio jack connector in my next project:https://lcsc.com/product-detail/Audio-Video-Connectors_Boom-Precision-Elec-PJ-320B_C18594.htmlNow my question is - which pin corresponds to left / right channel and GND?Manual:https://datasheet.lcsc.com/lcsc/1811132022_BOOMELE-Boom-Precision-Elec-PJ-320B_C18594.pdfI asssume, 1 is GND, 2 is Left Channel and 3 is Right Channel?Am I correct?

author: jbeng
author_rank: Regular Contributor
timestamp: May 23, 2021, 06:47:56 pm
content: On the earbuds I often use (Skullcandy brand) the earpieces are marked with L and R - the sleeve, pin 1 on the datasheet for your jack, is common. The ring (pin 2), connects to the right and the tip (pin 3) to the left.It's my understanding that this is pretty much a standard connection arrangement on a 3.5mm TRS setup.

author: Benta
author_rank: Super Contributor
timestamp: May 23, 2021, 07:00:50 pm
content: Audio jacks are standardized. 1/4", 3.5 mm or 2.5 mm makes no difference.Sleeve: always groundPoint: left or for mono: signalRing: right

author: tooki
author_rank: Super Contributor
timestamp: May 23, 2021, 07:19:54 pm
content: Red, right, ring. And with the sleeve being ground*, it leaves the tip to be left (usually white).*except on 4-pole plugs with microphone, where the sleeve is usually mic, and ground is ring 2.
Audio mixer accept balanced and unbalanced, how does it work? - Page 1
Forum section: electronics / projects

author: fls
author_rank: Contributor
timestamp: August 15, 2018, 05:10:48 pm
content: Hi,Dave showed a Audio USB Interface of Rode and went through the circuit. Than a question popped up...:I'm playing around in the theater with some audio equipment and was wondering how it is possible that a single input can handle both balanced and unbalanced signal?Take a jack plug as an example. If you have Tip as hot and Ring as cold, the amplifier handles it as an balanced input.If (in case of the (digital) audio mixer I'm using) the Tip is hot and the Ring is Ground/Sleeve/Shield, the amplifier handles it as unbalanced.Assume that the signal is 2Vpp. So an unbalanced signal is just that, 2Vpp. However in balanced it is 1Vpp for Hot and (-)1Vpp for cold.So how is the amplifier circuit in the audio mixer working?Can anyone point me at a schematic of an amplifier circuit that can handle both?

author: David_AVD
author_rank: Super Contributor
timestamp: August 15, 2018, 08:54:55 pm
content: A balanced input stage is processing the signal between the hot and cold inputs. If one of those inputs is connected to ground (unbalanced) it's still doing the same. In your theoretical case there's still 2V p-p in each case.

author: JS
author_rank: Frequent Contributor
timestamp: August 15, 2018, 08:57:08 pm
content: Any differential receiver would handle unbalanced signal, just connect the cold input to ground. In fact is a better way to do so, as you can connect the shield directly to the chasis and sense the chasis voltage.Also, all inputs are differential, you just compare to points to get a voltage, but what you are thinking as unbalanced receiver gets the reference always from ground, and if ypu connect that ground to the amp you have one of three non ideal conditions. A ground loop connecting the shield to chasis and circuit ground at the receiver input, the shield connected to the k put but not the chasis directly or the shield connected to the chasis directly and the sense voltage from circuit ground. Ground loop is a known bad. Not connecting the shield directly to the chasis makes the shield useless to shield RF, and sensing from ground and not from chasis makes a noisy sensing of the input.A differential input signal will have 6dB more dynamic range than a single ended one, as the input stage must handle your 1V peaks, the differential signal will have 4Vpp amd the single ended only 2Vpp.Note that balanced and differential are different concepts, and you can have one without the other. For now I leave you with the homework to look for that.JS
Audio Op-Amp - Variable output impedance - Page 1
Forum section: electronics / projects

author: Mike Warren
author_rank: Unknown
timestamp: January 16, 2014, 03:20:04 am
content: I need to have a adjustable output impedance of 1K to about 20K from a TL074 or similar op-amp. See the attached picture.The problem is that I need 4 channels to be set at the same value. I could do it with 4 preset pots, but then I will need to make sure all pots are set identically. Realistically, this is probably what I'm going to need to end up doing, but I thought I'd ask here first just in case someone here has a clever idea.They only ever need to be set once and I don't have room or budget for a 4-gang pot.Actually, on further thought, I really don't need it completely variable, I could cover every situation with values of 1K, 5K, 10K and 20K. Tolerance can be +/-20% as long as all channels are within 5% of each other.Cost, as always with my projects, is a major consideration.

author: Rufus
author_rank: Super Contributor
timestamp: January 16, 2014, 04:35:01 am
content: The attached does 1/5/10/20 by fitting no or one of 3 jumpers.A single pole 4 way switch could replace the jumpers.

author: Mike Warren
author_rank: Unknown
timestamp: January 16, 2014, 04:45:23 am
content: That will work, thanks.I can make the jumpers PCB solder jumpers, which means zero cost per unit.
Audio Oscillator Testing Evaluation and Distortion Analysis - Page 1
Forum section: electronics / projects

author: Zenwizard
author_rank: Regular Contributor
timestamp: September 25, 2025, 02:52:08 pm
content: I did a video recently comparing various oscillators that I have in use around the lab. I thought the findings were some what interesting so I though I would share here. There is a video out on you tube link below to the video on the topic. Screen shots attached for any one interested.Test frequancy - 1KhzTest Amplitude - 3.25x Vrms to keep things consistent.Video Link -
Audio out circuit for cellular device - Page 1
Forum section: electronics / projects

author: 8086
author_rank: Super Contributor
timestamp: May 24, 2013, 12:48:25 pm
content: I want to have a 'universal' audio output (akin to the headphone output on an MP3 player etc) from a cellular module.Module here:http://uk.farnell.com/huawei/mg323-b/gsm-modem-huawei-quadband-lcc/dp/2305903The module can apparently drive an 16 ohm impedance headset directly, but I wonder if this could be an issue if someone wanted to plug in anything else, as they might do to an MP3 player's output.I am thinking it may be possible to use a couple of op-amps to simply buffer the output? Is it that simple or am I way off?
Audio powered VU? any circuits - Page 1
Forum section: electronics / projects

author: dave_j_fan
author_rank: Regular Contributor
timestamp: August 13, 2016, 05:11:48 pm
content: CAn led vu meter run offf headphone audio,means I want to boost the audio signal to say 6v and run the VY circuit ( trasistor typ)will be fun add on to phones laptops

author: dave_j_fan
author_rank: Regular Contributor
timestamp: August 14, 2016, 01:53:10 pm
content: Quotewell its a doable thingy ....avoiding vv special chips is one aspect of the designthank u for the reply .i have good and bad newsa 5mm normal red LED gave nice glow via JT circuiton a iphone5 with volume fullsadly if we load the audio lines with headphone it doesnot workQuoteluv physical vu!As of now such a thingy will run on speaker wires with a small amount of tweaks ( planned to make on the headphone out .. will wait till someone give a trick )

author: Audioguru
author_rank: Super Contributor
timestamp: August 14, 2016, 02:59:45 pm
content: Audio amplifiers are designed to drive linear headphones and speakers. A VU meter LED display circuit draws high current pulses that will cause severe distortion to the audio output.Use a rechargeable or disposable battery to power the VU meter circuit instead.

author: dave_j_fan
author_rank: Regular Contributor
timestamp: August 14, 2016, 05:01:09 pm
content: concept was a stand alone..but seems itz not that simple .yes distortion will add up ...
audio priority circuit - Page 1
Forum section: electronics / projects

author: mMrOler
author_rank: Newbie
timestamp: August 24, 2012, 03:00:16 pm
content: Hi,I'm looking for a circuit with 2 inputs and 1 output that would switch of input 1 and switch on input 2 whenever a certain threshold is reached on input 2.I would use this to switch of my mp3 player in order to listen to my(yet to be acquired) walkie talkie.Would it be possible to also switch of input one during transmitting?

author: Rerouter
author_rank: Super Contributor
timestamp: August 24, 2012, 11:37:56 pm
content: it is not hard to do, it just depends on how long after crossing that threshold you would want it to remain on the walky talky input, so that you dont have have it crossing back between words,here would be your circuit, a peak detector,http://tinyurl.com/ck39qpathe 470K and 10uF make an rc network so that it resets after about 1.8 seconds,and the 2 op amps are being used as comparitors to drive the n channel mosfets,and the 5V between them would be your threshold level,hope it helps

author: Hobgoblin612
author_rank: Contributor
timestamp: August 25, 2012, 04:45:20 am
content: An easy way to do it would be to use a VOX switch kit like this one:http://www.jaycar.com.au/productView.asp?ID=KC5172Then just switch the relay to a DPDT one.

author: mMrOler
author_rank: Newbie
timestamp: August 25, 2012, 02:54:17 pm
content: Thanks, I will definitely solder up the circuit. Btw, the circuit simulator is pretty cool.I came across the VOX switch as well, yet I'm not sure how to replace the microphone with a direct output from the walkie.Thanks guys!
Audio Project - Page 1
Forum section: electronics / projects

author: noSun
author_rank: Contributor
timestamp: July 10, 2015, 04:40:42 pm
content: Created inexpensive audio device to record guitar.Video features Blender anim, 3D printer in action, schematic, assembly & demonstration.other projects ....https://www.youtube.com/playlist?list=PLn5mGAed9x54EjulLXxyrC_TQ1Mvl9ypK
Audio Recording Solution Help - Page 1
Forum section: electronics / projects

author: yanir
author_rank: Regular Contributor
timestamp: August 15, 2014, 09:38:33 pm
content: Hi Guys, I'm looking for a decent (low cost) solution to add audio recording to a project. I am using a microcontroller to do a variety of other tasks, and although it could do the audio recording, it would interfere with the other things it needs to do. What I'm looking for is a part that can take the mic input and record the audio compressed to a spi flash, for later retrieval by the host microcontroller (via SPI).I found some parts but nothing that seems perfect. Hoping someone has already come across something.ThanksYanir

author: yanir
author_rank: Regular Contributor
timestamp: August 15, 2014, 11:01:29 pm
content: So after doing more research it seems like a second microcontroller is likely the best way to go. I get everything I want going this route.
audio related   - Page 1
Forum section: electronics / projects

author: angelothewolf
author_rank: Contributor
timestamp: March 19, 2013, 03:20:09 am
content: hi everybody, im here to talk, or to hear actually about a transducer: the tapeheadI need a material to put an audio signal with this transducer ( other than tape, of course)any ideas???

author: c4757p
author_rank: Super Contributor
timestamp: March 19, 2013, 03:51:42 am
content: Huh?

author: Psi
author_rank: Super Contributor
timestamp: March 19, 2013, 04:14:53 am
content: There was a documentary on youtube that someone posted a while back.They made some magnetic tape on camera and recorded speech on it.Anyone remember it?

author: SeanB
author_rank: Super Contributor
timestamp: March 19, 2013, 04:11:48 pm
content: magnetic toner fused to a paper tape works, just like old iron oxide tapes. Or use a second one to act as a coupling coil to it, used in the in car audio input units you find all over.

author: G7PSK
author_rank: Super Contributor
timestamp: March 19, 2013, 04:20:50 pm
content: Wire or steel ribbon or steel disc any magnetic material can be recorded on it really is just down to what works best.

author: angelothewolf
author_rank: Contributor
timestamp: March 20, 2013, 01:20:22 am
content: Quote from: SeanB on March 19, 2013, 04:11:48 pminteresting...

author: angelothewolf
author_rank: Contributor
timestamp: March 20, 2013, 01:30:06 am
content: Quote from: G7PSK on March 19, 2013, 04:20:50 pmyep, im thinking in the wire metod like the old binson delays, but its quite a bit dificult to recreate. im not sure on what aspect of the magnetized material depends the fidelity of the recording??about the Binson....http://www.effectrode.com/binson-echorec-memory-system/
audio signal muting - Page 1
Forum section: electronics / projects

author: zzattack
author_rank: Regular Contributor
timestamp: August 04, 2017, 04:10:45 pm
content: My car speakers output a loud popping noise when the headunit turns on/off. In this headunit the pre-amp signals are connected in parallel to the internal amplifier.I believe the internal amplifier is instructed to mute during poweron/poweroff conditions, thereby preventing the noise. Does that make sense?Clearly the pre-amps are unaffected by this muting. I can think of 2 ways to fix this, but am unsure whether these actually help.1) I could add a FSA551 analog switch to disconnect the pre-amp signal from the RCA outputs. If we detect the muting condition then we can use that to drive the switch.I'm unsure whether this would work, because I don't understand the cause of the popping noise. If instability in the supply net causes noise on the signal lines, then wouldn't the analog switch suffer the same noise causing similar noise to be generated on the 'disconnected' pre-amp?2) Second alternative would be to quickly disable the upstream devices by pulling their remote enable signal low. This will probably work if the upstream devices turn off fast enough, but they seem to stay on for about another half a second after cutting its enable signal. So I anticipate this would only reduce the popping noise and not eliminate it entirely.Any advice?

author: ssashton
author_rank: Frequent Contributor
timestamp: August 06, 2017, 12:11:14 am
content: This might help give you some ideas -http://sound.whsites.net/articles/muting.htmlYou probably want to read the section on JFET muting circuits which are muted when the power is removed / un-mute when power is on. Other type of circuits usually need power applied to enable mute, which means you need the circuit to enable when you switch the head-unit off and I assume that is impracticable.
Audio Spectrum Analyser, Sig Gen, LCR meter and more using Sound Card - Page 1
Forum section: electronics / projects

author: jimmc
author_rank: Frequent Contributor
timestamp: April 03, 2010, 10:19:33 am
content: I came across this website a while ago...http://www.sillanumsoft.org/ZRLC.htmI've used older versions the software for some time and the Spectrum Analyser works well,the latest version has the facility to measure R, L & C with a simple external circuit (two OP-Amps and a few resistors + decoupling!).Jim

author: reyntjensm
author_rank: Regular Contributor
timestamp: December 19, 2019, 03:27:41 pm
content: Hello everyone,This is my first post in the EEVblog forum. I'm already following Dave his youtube for years now and learned a lot from him! I now encountered an issue which i'm unable to solve and i hope somebody within this forum can help me further.I'm working on a school project and i made an open source LCR meterhttps://www.element14.com/community/groups/open-source-hardware/blog/2019/07/23/building-an-lcr-meterfollowing this thread. I made the PCB and tested this with a scope an signal generator and it works fine. When i try to get the software working with my scarlett 2I2 interface, i don't get it to work. When i try to calibrate i receive the following errors( see attachments). I have no idea how to solve this issue? I tried all the different settings and receive always the same result. Anyone who could help me further with this or can export his settings for this software using a focusrite scarlette 2i2?I already tried to get i touch with the programmers for this software, with no luck.I hope some genius here on the forum could help me further with this.Thanks to you all!

author: ogden
author_rank: Super Contributor
timestamp: December 19, 2019, 04:06:24 pm
content: Which software version and operating system you use? Did you tryother software versions? If not - try.

author: reyntjensm
author_rank: Regular Contributor
timestamp: December 19, 2019, 04:20:13 pm
content: Dear jimmc,Thank you for your reply. I forgot to mention what version i used.Since the thread on element14 is using version 2014 i used the same version as in the thread, this doesn't work. Older and newer versions( 2011 and 2019) are not stable, i always receive a random error about floating point operation when i use those versions. The 2014 version looks stable. I'm using it on a windows 10 device and tried other computers and other sound cards. So it really has to do something with the software. I tried some other software package's i found online but also with no good result.
Audio transformer bobbins - Page 1
Forum section: electronics / projects

author: mishy
author_rank: Newbie
timestamp: July 05, 2023, 06:58:41 pm
content: I'm looking to repair a transformer, but am having trouble finding the parts...the bobbins and the cores. Looks like it's a ribbon mic bobbin. 15mm long, flange is 8mm by 6mm! Are there any sources for the parts?

author: Kim Christensen
author_rank: Super Contributor
timestamp: July 05, 2023, 07:31:21 pm
content: Did you look throughDigiKey's site?They have a selection of bobbins.Aliexpress has a bunch too, but it's much harder to search there.An alternative is to make friends with a 3D printer guy.

author: mishy
author_rank: Newbie
timestamp: July 05, 2023, 09:03:49 pm
content: I'll check out digikey! thanks!
Audio transformers and tubes for HIFI - Page 1
Forum section: electronics / projects

author: luiHS
author_rank: Frequent Contributor
timestamp: January 15, 2024, 04:50:50 am
content: HiCould anyone recommend good manufacturers of output transformers and tubes for HIFI audio amplifiers?.For output transformers I know the manufacturers Hammond, Lundahl, Tamura and Toroidy. I have here Hammond 1627SE for a 2x25w single ended with 6550.For tubes I have here Ruby Svetlana brand tubes, which I don't know if they are two brands or Ruby the manufacturer and Svetlana the model, this for 6550 tubes.

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: January 15, 2024, 09:55:13 am
content: Hi luiHS,Svetlana is the manufacturer (https://www.svetlanajsc.ru/),Ruby is just the marketing-name.Lundahl know their job really well. Tamura has a good reputation.Hammond is not the best but okay.Good luck

author: Circlotron
author_rank: Super Contributor
timestamp: January 15, 2024, 10:39:32 am
content: Here's a good place to ask if you haven't already tried ->https://www.diyaudio.com/community/forums/tubes-valves.5/
Audio Visual Project - I made a fun toy! lol - Ideas? Thoughts? Comments? - Page 1
Forum section: electronics / projects

author: PhynixViking
author_rank: Regular Contributor
timestamp: December 29, 2012, 01:24:33 am
content: SO! I made a fun "toy."I don't know what else to call it then a toy. It doesn't have any "practical" uses and it if VERY simple, BUT its fun!Here is a youtube video of it.Ummm... yyyeeeeaaa Sorry I've been sick so I sound off and tired and bla!But, anyone have any ideas?Either way, thought it was something fun to share.The Audio Amplifier used in it is a Stereo 15Watt in Bridged mode. With a VERY simple circuit.All that is connected to the AMP IC is a transformer, with a diode bridge, a grand total of 3 capacitors and a couple resistors, a switch, led, and a potentiometer. That's it!Notes covered in video or maybe forgotten about:*Fan is 12v DC at 0.17 Amps anything more then 0.25 amps will not turn.*The output from the "bench diode" bridge is very unstable DC. It varies from about 1v to 8v or so, very quickly. Adding a electrolytic capacitor did nothing. (well not much at all) I tried 33uf, 47uf, 100uf, 220uf, and 470uf no change noticeable.*Speaker is 8 OhmWant to know anything else feel free to ask! ^__^

author: SeanB
author_rank: Super Contributor
timestamp: December 29, 2012, 05:01:05 am
content: Capacitor across the coil will help. Larger means longer time on, but then it needs more power before it switches on. You probably will be better off using a 6V relay on it.