hybridfree/eevblog-posts huggingface dataset:
Attenuator Connector Gauge - Page 1
Forum section: electronics / beginners

author: staticshock
author_rank: Contributor
timestamp: November 22, 2024, 02:11:23 pm
content: Stepping into the world of RF. Can someone explain the purpose of a connector gauge? What is the significance of the measurement and what does it mean for the attenuator?

author: tooki
author_rank: Super Contributor
timestamp: November 22, 2024, 03:30:17 pm
content: So first off they’re not specific to attenuators. It’s just an RF thing.One of the things that makes coaxial connectors special is that they maintain the characteristic impedance of the cable through to the other side. So a 50 ohm connector, properly terminated to 50 ohm cable, ideally shows no change in impedance as the signal passes through.Part of maintaining consistent impedance is that the dimensions meet tolerances. A lower quality connector may exhibit impedance discontinuities. (I assume this is why, for example, some SMA connectors are rated for higher frequencies than others.) One can measure and see this using a VNA (vector network analyzer).The gauges are simply a tool to measure the critical dimensions of a connector.Also, even the torque with which a threaded coaxial connector is tightened affects the impedance through it, which is why there are special torque wrenches for them. (For example for SMA).

author: shabaz
author_rank: Frequent Contributor
timestamp: November 22, 2024, 03:57:03 pm
content: If by gauge you mean the tool to measure depth, then that's quite a specialist tool. It would probably be used by only a very tiny percentage of people working with RF. For instance, if you're in the business of building or selling calibration standards, you would have a use for it for that task.Most other RF fields of work either(a) not do such measurements at all, and rely on buying at least decent quality cables, adapters, calibration standards that come with a specification, and so on, and(b) rely on using less precision (compared to a gauge), known depth (length) tools, and torque wrenches for the purpose of assembling RF connectors to cables and for mating connectors together.If by gauge you meant cable thickness, then probably the Wikipedia 'Coaxial Cable' page is an excellent start. It lists a variety of common RF cable dimensions and related information. It's not specific to attenuators, however.If by gauge you meant connector size, i.e., connector type, then that is one of the attributes when selecting an attenuator, mainly for practicality, since it needs to fit the rest of the system (cables, connectors) where it is to be used, although conversions are possible with adapters.
(solved) Attenuator values for headphone circuit - Page 1
Forum section: electronics / beginners

author: serprinss
author_rank: Newbie
timestamp: January 12, 2025, 09:58:31 am
content: HelloI am trying to add a headphone output for a cheap boombox device.I found thishttps://sound-au.com/project100.htmcircuit but the resistor values only go down to 10w at 4Ω. The amp in my device says it outputs 2.5w at 4Ω (datasheet here:https://www.eeweb.com/wp-content/uploads/projects-member-projects-utc8227-1367701357-171108-032246.pdf)I worked out that this is an L pad attenuator however as I am not familear with this topic I am not sure how to calculate what value of resistor I need.

author: magic
author_rank: Super Contributor
timestamp: January 12, 2025, 10:13:13 am
content: It tries to target the retarded 120Ω standard which nobody ever cared about. In reality, the lower the output impedance, the better.2.5W into 4Ω is about 3Vrms. Some larger headphones could basically run from this directly, no resistors whatsoever.If you want to push it down, say 1.5Vrms, then you need two equal resistors such that their sum is about 4Ω (if you disconnect the speaker) or several times higher than 4Ω (if you don't). That's all, no R3 necessary at all.For 1Vrms, same thing but 2:1 ratio resistors. And so on.

author: lakis70
author_rank: Contributor
timestamp: January 12, 2025, 11:56:02 pm
content: Whats the impedance of your headphones?

author: serprinss
author_rank: Newbie
timestamp: January 15, 2025, 05:21:11 am
content: That worked great. thanks.to clarify for anyone finding this in the future I arranged two 2Ω resistors in an l pad circuit similar to the 2nd circuit found athttps://sound-au.com/project100.htm.I used a double pole double throw (DPDT) socket which means you have two inputs each going to one output when something is plugged in, and another when it is not. this meant I could connect the positive left and right audio leads and connect the speakers to the side that is connected when it is unplugged and the socket itself to the other (through the resistors).
Attenuator - Page 1
Forum section: electronics / beginners

author: graphtronics
author_rank: Contributor
timestamp: May 08, 2018, 01:43:52 am
content: Is there an equation(s) to calculate the the resistors values for an specific dB output?For instance for a 10 V input voltage shows a 10 mV output whenever the pot is a max value.What will be the limits of attenuation?How to improve the design?

author: Old Printer
author_rank: Frequent Contributor
timestamp: May 08, 2018, 01:47:52 am
content: There are several others as well.

author: graphtronics
author_rank: Contributor
timestamp: May 08, 2018, 02:11:14 am
content: Thanks for the video that contains valuable info plus the linksI have not explored all 3 links in detail yet.The attenuator is for DC and variable outputThe closest I've got is a T-Bridge with dual gang pot.The circuit uses a single gang one.Any advice will be appreciated.
AtTiny fails to connect to arduino as ISP/USB ASP - Page 1
Forum section: electronics / beginners

author: wintech
author_rank: Contributor
timestamp: April 23, 2020, 03:15:16 pm
content: Hello everyone,I had tried to upload a code to attiny and I get this message every time.avrdude: initialization failed, rc=-1Double check connections and try again, or use -F to overridethis check.I had checked the connections and it still shows the same message. I had changed the jumper wires ,the breadboard, the attiny,the arduino board and I tried to use a USB ASP but it didn't work.I hooked up my oscilloscope to the A2 pin of the attiny and it look like it's trying to do something.

author: SmokedComponent
author_rank: Regular Contributor
timestamp: April 24, 2020, 09:43:09 pm
content: Have you put a 10µF capacitor between reset pin of the Arduino programmer board and ground?

author: wintech
author_rank: Contributor
timestamp: April 25, 2020, 12:12:12 pm
content: Quote from: SmokedComponent on April 24, 2020, 09:43:09 pmI did
ATtiny package wierdness - Page 1
Forum section: electronics / beginners

author: M@rkBot
author_rank: Newbie
timestamp: February 22, 2014, 02:33:02 pm
content: hi,so i have been developing a PCB for a product and after testing using a DIP package i miniaturized the design to use a QFN package. after downloading the library for the footprint for eagle (avr-4) i dropped the package and had some boards made up.but after assembling and trying to test i realised that the footprint is different too the package. so i dropped the TINY24/44/84-MU, apparently HP-VFQFP-N20 and its totally mismatched, apparently its a 20pin QFN/MLF20, but no matter how hard i search or look at datasheets i cannot find one with a pin pitch greater than 0.50 and the pad the library dropped is 0.65.this is the first time iv dealt with QFN packages and i don't really know a great deal about what im doing with them, so any help with finding out what im obviously not getting is much appreciated. i need to move along with this prototype quickly so i would like to avoid having more boards made and waiting for a week or two for them to arrive.thanks,mark.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: February 22, 2014, 03:42:37 pm
content: Heres a datasheet for the HP-VFQFP-N20 :http://datasheet.octopart.com/T7024-PGS-Atmel-datasheet-77070.pdfPage 16 has the pad info .

author: M@rkBot
author_rank: Newbie
timestamp: February 22, 2014, 04:08:05 pm
content: thats the footprint allright!!!!no idea why its been dropped for a tiny84 when i cannot find one in that package??thanks.

author: Neverther
author_rank: Regular Contributor
timestamp: February 22, 2014, 07:22:03 pm
content: The Atmel datasheet specifies the spacing at 0.50mm.Never assume, always measure, even on design phase.Learned that as I got 4 different width SO quick adapters.Also attiny20 has 0.45 spacing for the packaging. 20 pins, same as attinyX4, but 3x3mm size instead of 4x4mm.I'm using kicad here, so I have to somewhat pick/make my own footprints.
ATtiny - Page 1
Forum section: electronics / beginners

author: Rihards Veips
author_rank: Contributor
timestamp: April 04, 2014, 05:17:42 pm
content: I programmed my ATtiny microcontroller with an Arduino [Blink on pin 0] - the programming worked but I have a problem with my ATTiny - when I plug in the LED it turns on but doesn't turn 100% off, it stays at about 40%Are there any solutions for that?

author: Neverther
author_rank: Regular Contributor
timestamp: April 04, 2014, 05:25:31 pm
content: Schematics/code/chip?Not all chips/pins supply the 20mA current arduino can.Are you just connecting the directly to tiny pin and ground, or with resistor, or using internal pullup to light the led a little bit, or using it to control a NFET that drives some higher power led?

author: 128er
author_rank: Regular Contributor
timestamp: April 04, 2014, 05:26:37 pm
content: Did I understand it right? You connect your LED to PIN0? Do you mean PortB0? Did you program the TINY over the ISP-interface?

author: Rihards Veips
author_rank: Contributor
timestamp: April 04, 2014, 06:01:27 pm
content: Quote from: Neverther on April 04, 2014, 05:25:31 pmAttiny85 1Mhz internal clock - not using a resistor

author: Rihards Veips
author_rank: Contributor
timestamp: April 04, 2014, 06:03:20 pm
content: Quote from: 128er on April 04, 2014, 05:26:37 pmLed connected to PB0 programmed over Arduino as ISP
Attiny45/85 clock problem - Page 1
Forum section: electronics / beginners

author: mrmp17
author_rank: Contributor
timestamp: December 19, 2013, 05:44:03 pm
content: HiI have some problems with my little project that contains attiny85 microcontroller. I can't get attiny85 to work properly. It seems like the clock runs somehow to slow.If I write a very simple code (I write in Atmel Srudio 6.1) that togles led on the output (1000ms on, 1000ms off) it stays on and off for about 9 seconds. This test program uses util/delay.h with defined F_CPU (I'll post the code below). Also a program I downloaded seems to work just fine but about 9 times to slow.I was playing with fuses, tried everything but....doesn't work... Same thing with external crystal oscilator. I tried with attiny45 but it does the same thing. The code I wrote works prfectly on atmega32 with internal RC oscilators and external crystal.I need to get attiny microcontrollers working but I don't know what to do ,so a little help would come handyWhat am I doing wrong?Code:#define F_CPU 8000000UL#include <avr/io.h>#include <util/delay.h>int main(void){DDRB = 0b11111111;PORTB = 0b11111111;while(1){PORTB = 0b00000000;_delay_ms(1000);PORTB = 0b11111111;_delay_ms(1000);}}

author: Hideki
author_rank: Frequent Contributor
timestamp: December 19, 2013, 06:07:20 pm
content: Did you try the turning off the CKDIV8 fuse? The default is to divide the clock by 8.If you want to be sure it's running at full speed, you can also override the division by setting the CLKPR register.

author: mrmp17
author_rank: Contributor
timestamp: December 19, 2013, 08:49:55 pm
content: Thank you!Didn't even knew of this fuse....Everything works just fine now!It's strange that this fuse is enabled in default fuse setings.
Attiny85 in Circuit Programming Issue - Page 1
Forum section: electronics / beginners

author: vitormhenrique
author_rank: Unknown
timestamp: July 09, 2018, 07:07:15 pm
content: Hello Everyone,I'm designing a small PCB to help a friend, it would basically be a buzzer for his drone that would function as a normal buzzer when it's connected to power, but on a event of loss of power it would beep at defined intervals to help him find his drone.I have the schematic attached.One problem that I'm fighting now is that if I populate the PCB the Attiny85 refuses to be programmed. I troubleshooted the issue with the Li-ion battery charger on the board (MCP73831) and could even reproduce the issue one a breadboard.I don't understand why I'm having this issue, the ISP header has a power supply that should be different from the +5V and the +Bat voltage supply.Does anyone has an idea of why is this happening? I can just put a solder jump on the board, and leave if disconnected before programming, but I really want to understand what is going on.Thank you very much for any lead,Vitor Henrique

author: IconicPCB
author_rank: Super Contributor
timestamp: July 09, 2018, 10:34:33 pm
content: Your MOSI line is held at +5V constantly.The lines coming from the programing header need to be isolated from the rest of the circuit ( typically using a resistor such that the programmer has a chance to drive the programing lines .So disconnect your MOSI line from +5V or put a resistor from +5V to MOSI and you will be able to program the the micro.

author: vitormhenrique
author_rank: Unknown
timestamp: July 09, 2018, 11:34:26 pm
content: That is not it, there are diodes preventing the VCC voltage to backfeed to the +5V and +Bat voltages.Tha a look on the top of the schematics, I'm 100% sure that the issue is with the MCP73831, when I take it out of the PCB it works, whenI solder it back it stop programing the Attiny85.I just don't understand why.

author: IconicPCB
author_rank: Super Contributor
timestamp: July 10, 2018, 01:40:22 am
content: Mosi is connected to +5V directly.Mosi is also connected to the battery charger directlyProgrammer CAN NOT drive battery charger..Shove a resistor between mosi and +5V this will reduce LOADING on programer mosi signal and allow it to program the processor rather than power up charger.

author: vitormhenrique
author_rank: Unknown
timestamp: July 10, 2018, 01:59:49 am
content: Ahhhh! got it! now it makes sense! I'll try that! thanks!
ATX bench power supply (alternative) - Page 1
Forum section: electronics / beginners

author: Cliff Matthews
author_rank: Unknown
timestamp: August 30, 2015, 07:58:28 pm
content: Since ATX bench threads seem to go on forever, I suggest someone (with more elegance than I) post a single prominent sticky titled "Good Non-ATX bench power supplies for novice builders"The very act of having that titleshould cut down on ATX thread clutterand provide newcomers with quick, solid candidates for bench supplies. (and please, I mean no offense to anyone)A possible candidate: Ink-jet printers are common "reusable refuse" from the computer camp, and I've not seen suggestions yet for using one or two (~28 to 32 volts DC @ 600ma to 1.5amps) to feed classic 317T/337T pairs for somethingSimple,Safe andSilent.On many, the outputs are unearthed, so outputs can be coupled for split pre-regulation (up to 64 volts). Add a resistor and 2 series diodes to each rail and you have the reference for the regulator on the other rail.Even if 2 plastic supplies have mains ground pins, don't use them. Instead mount and couple them inside a grounded enclosure (with fuse and switch) making sure to isolate the rest right up to the binding posts.For those that like that rough "ATX supply look", install a couple of 24v universal laptop adapters inside like this onehttp://www.ebay.com/itm/96W-Universal-Power-Charger-Adapter-AC-110V-240V-For-Laptop-Notebook-EU-Plug-SC-/251793362315.I suggest using an LM7805 to feed the fan with a pot on the adjust pin to vary it between 5 and 12volts (those regulators will need cooling). - Cheers!

author: jeroen79
author_rank: Frequent Contributor
timestamp: August 30, 2015, 09:41:58 pm
content: These still have the drawback of not having an adjustable current regulation.If you do something wrong then such a powersupply will let as much current as it can supply run through your circuit.Even if this is not as much current as an ATX PSU it may still damage your circuit.

author: Cliff Matthews
author_rank: Unknown
timestamp: August 30, 2015, 10:43:59 pm
content: Quote from: jeroen79 on August 30, 2015, 09:41:58 pmFortunately LM3xx's are cheaper than crackers. Pass juice through a few power resisters via switches for the higher currents, and route through a wire-wound pot (say a hundred ohms) for the lighter circuits. You loose 1.25v but as long as a budding hobbyist gets 25v out to the posts for $20, they're doing OK.
ATX Lab Power Supply Help. - Page 1
Forum section: electronics / beginners

author: Prospero
author_rank: Newbie
timestamp: December 05, 2014, 08:32:35 pm
content: Hi,I recently converted an ATX PC power supply to a lab supply. I connected -12V, +12V, 3.3V, 5V and Ground to binding posts.I added 2 LEDs to the Gray and Purple wires and connected a 750ohm resistor between the LEDs and ground.Then I put 2 10w 10ohm resistors in series between +5V and Ground.Finally, I added a switch between The Green wire and Ground.It all worked fine the first time, then when I flicked the switch connecting the Green wire to Ground off and on again it just caused the fan to twitch. One of the LEDs was lit, but the power supply was in standby. So I plugged it out and in again, it worked fine flicked the switch on and off again and the same problem, after plugging it out and in again the problem still continued.So, when I plug it into the mains one of the LEDs turn on but when I turn on the switch the fan inside twitches. I have tried bypassing the switch by connecting the Green wire to Ground but I still have the same problem.Any solutions?
ATX power supply rebuild - Page 1
Forum section: electronics / beginners

author: icecold
author_rank: Newbie
timestamp: December 27, 2016, 12:21:37 pm
content: Hello,I rebuilt an ATX power supply to regulate the 12V line and made it adjustable. After disabling the under-voltage protection it can go down to 3V now, but below that it starts to freak out (hissing noises and awful waveforms across the transformer). I think this is because of pulse-skipping.Is it possible to make it stable below 3V?Its very similar to this one:http://320volt.com/wp-content/uploads/2011/05/patriot-switching-power-supply-sg6105d-cef2n60-ee19-ee16-ei33-f12c20c-s20c40c.pngthanks

author: Seekonk
author_rank: Super Contributor
timestamp: December 27, 2016, 01:20:47 pm
content: I don't see much reason for it. The real problem is that the output is opto isolated from the line power. You can't get below the 1.7V the led needs to turn on without another external supply.

author: icecold
author_rank: Newbie
timestamp: December 27, 2016, 01:43:15 pm
content: The opto is used for the 5V standby supply which works fine even if the main supply is unstable. I altered the feedback loop on pin 17 of the SG6105D to only regulate 12V and made it adjustable which works fine between 3V - 15V on the 12V rail. It must be something around T3 or its drive circuit which makes it unstable if pulses are skipped.

author: icecold
author_rank: Newbie
timestamp: December 28, 2016, 01:13:36 pm
content: It actually was a similar problem. The input of the error amplifier (SG6105D pin 17) is compared to a 2.5V reference which makes the output unable to go below this value. At the extreme setting of direct connection of the output to the input of the error amplifier the psu gets unstable (maybe because it bridges the filters).

author: danadak
author_rank: Super Contributor
timestamp: December 28, 2016, 01:19:31 pm
content: You could always add an LDO but that wastes power, very inefficient.But then if you "synched" the LDO ref leg to your control over the ATXVout might be able to minimize power loss while still keeping solutionin regulation. Just a thought.Regards, Dana.
ATX PSU question. Why 3.3 and 5 volts share the same output diode? - Page 1
Forum section: electronics / beginners

author: dog80
author_rank: Regular Contributor
timestamp: May 02, 2014, 06:36:34 pm
content: All computer PSUs I've seen have a dual common cathode schottky diode for the 3.3 and 5 volt rails. The 12V rail on the other hand has a single diode all for itself.Why not separate diodes for 5 and 3.3?

author: mariush
author_rank: Super Contributor
timestamp: May 02, 2014, 06:50:56 pm
content: Some power supplies may work like you say, but it's not the rule.Most don't, and a lot of new power supplies don't even have separate outputs, just a 12v and then they use 12v -> 5v and 12v->3.3v dc-dc converters.

author: SeanB
author_rank: Super Contributor
timestamp: May 02, 2014, 06:55:19 pm
content: Cheap power supplies take the 5V rail and use a further switching regulator ( or a magnetic buck converter in some) to make the 3V3 rail from it. You will see in the ratings that he 3V3 and 5v rails share a power rating ( if the datasheet is even close to correct) while the 12V rail has a separate rating.

author: amyk
author_rank: Super Contributor
timestamp: May 03, 2014, 12:39:06 am
content: Cost savings, mostly, and the fact that ATX evolved from AT which only had 12 and 5, so it must've been easier to add another regulator on the 5V rail to produce 3.3 than another winding on the transformer. This post-regulator is usually a saturable reactor.
Audible noise on switching supply (is it bad?) - Page 1
Forum section: electronics / beginners

author: hazuki
author_rank: Contributor
timestamp: July 19, 2013, 03:16:19 am
content: Hi all. I've put together a buck switching converter for one of my projects. I noticed that there is audible noise coming from the supply (maybe around 10kHz). The high pitch whine appears to be coming from the inductor. Should I be concerned about audible noise like this? My buddy's first reaction to the sound on my circuit was "that doesn't sound healthy."The switching frequency is actually much higher than the audible frequency (around 250kHz).Thank you!

author: Rerouter
author_rank: Super Contributor
timestamp: July 19, 2013, 03:26:21 am
content: its either the windings or the core vibrating, though if you have access hook up the output to a scope and see if there are any repetitive patterns close to 10Khzin general securing it better with some adhesive will make it quieter

author: AndyC_772
author_rank: Super Contributor
timestamp: July 19, 2013, 06:50:09 am
content: If a switched mode supply is making a sound you can hear, then there's some component of the switching waveform that's within the audible range. Since 250kHz is nowhere near that range, chances are your power supply is unstable and is switching in bursts, rather than producing a nice, consistent stream of pulses in which every cycle is the same.This behaviour is generally caused by one of two things: noise, or the wrong compensation network. If the layout is poor, then the controller's sense input gets a noisy signal, and pulse widths will vary quite randomly from one cycle to the next. Or, if it's poorly compensated, then the system will tend to oscillate - pulses will get wider and then narrower, often to the point of being skipped entirely, over and over again.A scope will show you very clearly which is the case. If your controller has an accessible compensation point (the output of the error amplifier), probe that too as it can give a better indication of whether the problem is noise or oscillation. If it looks like a sine wave, your control loop is unstable and the compensation network needs changing. If it's reasonably flat but noisy, then you need to look at your layout.

author: megajocke
author_rank: Regular Contributor
timestamp: July 19, 2013, 08:22:09 am
content: Maybe it's worth mentioning that it is also common and normal for unloaded or very lightly loaded supplies to do that because there might be a lower limit on the duty cycle forcing the supply into a pulse-skipping mode creating a lower effective switching frequency. As pulse skipping/burst mode operation can be beneficial for efficiency at light loads there can be reasons to want to introduce it on purpose.But if this is happening under load and is not by design it might not be good, causing for example higher RMS current stress on components than would be the case if every switching cycle was identical.BTW, hi Andy!
Audio amp as power supply? - Page 1
Forum section: electronics / beginners

author: brainwash
author_rank: Frequent Contributor
timestamp: July 05, 2013, 08:16:02 am
content: I haven't seen any design that discusses this, not that it would be extremely useful. Very few audio amp datasheets provide DC characteristics, a few of them supply a bandwidth. I thought in an amp design gain decreases (almost linearly) with bandwidth but at least for TDA2030 this seems not true. Is it oscillation at low frequency a reason for this?http://www.st.com/web/catalog/sense_power/FM125/CL1503/SC979/PF65115I also have this one in the drawer:http://offer-shem.narod.ru/data/tda/tda1011a.pdfand it does provide DC data and internal schematics but incomplete gain graphs.Obviously, I have a few of these laying around and was thinking of converting them to controlled PSUs for stress testing. They have really poor precision (0.1%-10%) especially when driven hard, but they provide shortcircuit and thermal protection.

author: Paul Price
author_rank: Super Contributor
timestamp: July 05, 2013, 08:24:13 am
content: Audio amps are not quite suitable for this purpose because most become unstable and oscillate with high capacitive loads, such as a filter capacitor on the "OUTPUT" of your audio power supply-amplifiers. This idea might work with small loads if you decouple the output with a 4 to 8-ohm resistor in series with the output, but the regulation might be rather poor except at low current loads.

author: brainwash
author_rank: Frequent Contributor
timestamp: July 05, 2013, 08:33:22 am
content: Good explanation, I didn't realize that they were designed for inductive loads.

author: hlavac
author_rank: Frequent Contributor
timestamp: July 05, 2013, 05:02:35 pm
content: Also, most audio amps have protection against DC current on output bacause that burns (literally) speaker coils.
Audio AMP Power vs THD+N ratio - Page 1
Forum section: electronics / beginners

author: glatocha
author_rank: Regular Contributor
timestamp: July 10, 2013, 11:43:57 pm
content: Hi,I am designing audio class D amp with TI TPA3125 2x10W amp.I have found the screen as attached showing THD+N vs supply voltage and output power.I would prefer to have lower THD+N and this 1 or 1.5W less power is ok for me. But how can I choose at which THD+N it will work?What determines which curve is actually working.I have the feeling that I misunderstand the whole concept of this. Can somebody help me out?Regards

author: David_AVD
author_rank: Super Contributor
timestamp: July 11, 2013, 12:30:31 am
content: Do you have a specific operating voltage in mind? If so, find that on the bottom of the graph. Follow it up to where it intersects the blue line (1% THD). Then see what max power output that corresponds to on the vertical axis of the chart.Basically, they are telling you the maximum power output vs voltage with 1% and 10% options.

author: w2aew
author_rank: Super Contributor
timestamp: July 11, 2013, 02:01:53 am
content: THD+N is a function of supply voltage and output power. For example, for a supply of 20V, the THD+N will be 1% or less if the output power is kept below 6W. If the signal is turned up to the point where the power exceeds 7W, then the THD+N will approach 10%. The curves are intended to show you how these three parameters are related.

author: glatocha
author_rank: Regular Contributor
timestamp: July 11, 2013, 09:12:07 am
content: So, basically if the Amplifier has a constant gain it will depend on my input amplitude?I think I am beginning to understand

author: David_AVD
author_rank: Super Contributor
timestamp: July 11, 2013, 10:01:11 am
content: yes

author: glatocha
author_rank: Regular Contributor
timestamp: July 11, 2013, 10:28:43 am
content: Thank you all
Audio amp question - Page 1
Forum section: electronics / beginners

author: Szewczykm
author_rank: Regular Contributor
timestamp: December 06, 2012, 05:16:00 pm
content: In another post I explained that I'm troubleshooting some buzz on a pinball machine sound board. Looking at the schematic, I'm curious as to why the designer did something. I'm very new to signal amplification so I apologize for my ignorance here.Attached is a schematic with some notes and the signal path highlighted in red.Audio leaves a DAC (TDA1543) and is fed into an LM833N op amp. The signal leaves the op amp, presumably amplified, and then enters an SSM2024 Quad audio amplifier. It leaves the output from the SSM2024 and enters *another* LM833N. The signal then leaves the LM833N and continues out to the power amp.I'm wondering why there are all of those amps in series before hitting the power amp. Is it that there is a point where the gain is too high and it gets noisy, so you just feed one into the other until it's "loud" enough for the power amp? Or is there something I'm missing where one is amplifying and one is filtering or something?EDIT: Also, can you tell me what C55 (just before the IN on U31) is doing? I'm guessing it's a filtering cap, but not sure what or why.Thanks for your input.

author: ciccio
author_rank: Frequent Contributor
timestamp: December 06, 2012, 06:25:07 pm
content: This is a very standard configuration. Some (20?) years old.The SSM2024 is a quad "current controlled amplifier", that means is an amplifier that has is gain controlled by an external current (or voltage) signal. You did not post the whole schematic, so I can't tell how the audio gain is controlled.Datasheet is herehttp://pdf1.alldatasheet.com/datasheet-pdf/view/92296/ETC/SSM2024.htmlIt needs to be driven by a low impedance source, thus the 200 ohms resistor from input to ground, and it's output is a "current", so it needs to be converted in a "voltage".The first op-amp is needed for integrating the DAC output, then it drives the SSM2024 whose output "current" drives the inverting input of the second op-amp.The second op-amp output "voltage" signal drives the power amplifier.The power amplifier is a single supply device, so it's input is at about 1/2 VCC.The op-amp is powered by a dual supply (plus/minus), so it's output pin DC level is zero volts (GND potential)Without C55 a DC current will try to flow from power amplifier input into op-amp output, resulting in some certain malfunction.C55 will block this DC current flow, but will allow AC signals to pass.Best regards
Audio amp voltages - Page 1
Forum section: electronics / beginners

author: christos
author_rank: Regular Contributor
timestamp: October 12, 2015, 03:40:24 am
content: http://s21.postimg.org/s4oem13c7/400_W_Mosfet_Power_Amplifier.pngDoes this work with lower voltage..lets say 40v instead of 70-80v that its supose to work?will it work with lower watts? what's the downside if it worksJust a question..trying to figure how audio amps works

author: kc8apf
author_rank: Regular Contributor
timestamp: October 12, 2015, 04:20:08 am
content: The overall design should work at lower supply voltages but many of the component values will need to change. For example, the bias resistors will need to be changed to get the appropriate bias currents.This is a push-pull design. Lowering the supply rail voltage is how you get lower power output. Consider the case when the upper output FETs are fully on, the output will be driven to +70V. Typical speakers are nominally 8 Ohm so the output current will be 70V/8R=8.75A. P=IV so P=8.75A*70V = 612W. The 400W rating presumes that you aren't driving it to the limits to keep the distortion low.

author: SeanB
author_rank: Super Contributor
timestamp: October 12, 2015, 07:14:57 pm
content: Also remember those Mosfets will have a threshold voltage, which limits the output voltage somewhat. Maximum voltage on the output will be around 10V lower than the positive rail, but the negative swing will go almost to the negative supply.Google quasi complimentary amplifiers, and look for the stuff by John Lindsey Hood on them.https://web.archive.org/web/20110720133138/http://www.tcaas.btinternet.co.uk/

author: Kleinstein
author_rank: Super Contributor
timestamp: October 12, 2015, 07:50:39 pm
content: The plan has a small mistake: the SB546 is a PNP, and needs to be. The plan shows an NPN symbol instead.Changing the bias (two 33 K resistors) is not that critical. It might still work at +-40 V.Less voltage means less power. Distortion will not change very much. With MOSFETs, there will quite some voltage lost on the positive side - so the loss in power may be more than one might expect.

author: Kappes Buur
author_rank: Regular Contributor
timestamp: October 12, 2015, 08:24:37 pm
content: Check this out as wellhttp://raylectronics.nl/pdfs/Crescendo_Millennium_en.pdf

author: christos
author_rank: Regular Contributor
timestamp: October 13, 2015, 03:55:40 am
content: Thx all of you..got what i needed..thank you! the schematic i posted was only an example, so i dont mind if its wrong .
audio amplifier output rms wattage question... - Page 1
Forum section: electronics / beginners

author: kasumyku
author_rank: Regular Contributor
timestamp: July 16, 2013, 08:26:13 pm
content: Hello everyone,When testing for rms output wattage of an audio amplifier, do all channels must have dummy loads connected in order get accurate readings, or just only one?Thanks!!!

author: Zero999
author_rank: Super Contributor
timestamp: July 16, 2013, 08:39:50 pm
content: All loads should be connected, to accurately measure the output power as the power supply voltage can drop under load.

author: kasumyku
author_rank: Regular Contributor
timestamp: July 16, 2013, 09:19:01 pm
content: thanks hero999 !!!

author: Odysseus
author_rank: Regular Contributor
timestamp: July 17, 2013, 01:56:25 am
content: To be technically correct, you will be measuringaveragepower, which is the product of the RMS (or heating value) of the voltage and current. The phrase "RMS power" or "RMS wattage" is a bit redundant.I remember this because I used the very same phrase when talking to a co-worker right before receiving a brief lecture from said co-worker.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 17, 2013, 06:36:56 am
content: Quote from: Odysseus on July 17, 2013, 01:56:25 amAnd rightly so! Even if the Root Mean Square value of a power waveform had any practical use,it still would not be the product of the RMS values of voltage & current.
Audio amplifier, purpose of diode - Page 1
Forum section: electronics / beginners

author: Simon123
author_rank: Regular Contributor
timestamp: January 31, 2017, 06:56:05 pm
content: Hello!I would like to know, what is purpose of diode placed over 39R and 10-12R resistor?Thanks

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 31, 2017, 07:03:43 pm
content: I am guessing to eliminate feedback / control of those transistors ?

author: Kleinstein
author_rank: Super Contributor
timestamp: January 31, 2017, 07:33:23 pm
content: The diode is there to limit the voltage lost at the resistors in cases of high negative output currents. It also makes the transition a little more symmetric, having two PN junctions for both the negative and positive half - at least for higher current.Sometimes one has the diode without the parallel resistor.

author: mzacharias
author_rank: Frequent Contributor
timestamp: January 31, 2017, 09:34:55 pm
content: I have seen them "built-in" to some (Darlington) transistors, such as the 2SB1647 and it's complement 2SD2560. Not sure they qualify as "damper" diodes but that is how I think of them. (I'm a repair tech, not an engineer)

author: Gary.M
author_rank: Regular Contributor
timestamp: January 31, 2017, 09:38:38 pm
content: That is a Quasi-complementary output stage and the diode adds some symmetry reducing hf distortion. If you google Baxandall diode you might find more info.Sent from my x600 using Tapatalk

author: David Hess
author_rank: Super Contributor
timestamp: February 01, 2017, 07:35:52 pm
content: The diodes across the output transistors and their emitter resistors prevent the output from exceeding the supply voltages which can happen with an inductive load. Some Darlington transistors have these diodes built in. Power MOSFET body diodes fulfill the same function sometimes.I was not familiar with the term Baxandall diode but after readingthis post, I understand the idea. It simulates the load provided by the base-emitter junction of the top output transistor on its driver on the lower driver which would otherwise see a different load. It is not required in a fully complementary output stage.

author: lordvader88
author_rank: Frequent Contributor
timestamp: February 03, 2017, 02:20:39 am
content: Guys please feel free to also explain from the beginning what these circuits and mini-circuits are actually doing. Hardly ever do I find videos of explanations through a circuit like this with any amount of step by step detail. And since so many non-EE don't get near enough detail.So many small circuits and mini-circuits that I still don't know or recognize or really know what they are meant to do.
Audio Amplifier Single Sealed Potentiometer - Page 1
Forum section: electronics / beginners

author: EEVaditya
author_rank: Regular Contributor
timestamp: January 22, 2018, 03:11:50 pm
content: Hello,I am looking for Audio Amplifier Single Sealed Potentiometer (RV097NS) 5 PIN B100K & B10K(See attached Image for your reference)But Tolerance is an issue for me. I want 1% tolerance.I saw on some online portals but they haven't mentioned the Tolerance as well as Make (Manufacturer)So, do the Potentiometers with above specifications come with 1% tolerance, if not what is the minimum tolerance for the same?Kindly guide.

author: Benta
author_rank: Super Contributor
timestamp: January 22, 2018, 03:21:27 pm
content: I can't remember seeing a pot with 1%, 10% is probably as good as you'll get. Applications for pots are normally not critical with respect to absolute value, things like tracking and linearity are more important.

author: Audioguru
author_rank: Super Contributor
timestamp: January 22, 2018, 05:12:15 pm
content: A potentiometer usually has a tolerance of 20% because its tolerance does not affect its output.Your dual pot is an extremely cheeeep Chinese no-name-brand one sold on ebay and Ali so its tolerance might be worse than 20%.Your pot is called a volume control but that is wrong because it is a linear pot. A volume control is supposed to be a logarithmic pot to match the logarithmic sensitivity to loudness of our hearing.

author: Zero999
author_rank: Super Contributor
timestamp: January 22, 2018, 06:24:48 pm
content: Quote from: EEVaditya on January 22, 2018, 03:11:50 pmChange the design so absolute tolerace is not an issue!Linearity is generally more important than absolute tolerance.Is it a volume control? If so, don't you want logarithmic, rather than linear?

author: retrolefty
author_rank: Super Contributor
timestamp: January 22, 2018, 08:43:02 pm
content: I too question your need of 1% for audio applications. Perhaps if you could explain your requirement(s) it might help us understand and come up with useful alternatives?If for a stereo application a balance control is usually specified, and as the human ear can only differentiate around +/- 1 db levels it kind of explain why such tight tolerance pots even if available are not very common in typical audio applications. Also as others have said linear pots suck when logarithmic taper is called for.
Audio crossover question - Page 1
Forum section: electronics / beginners

author: silviasol
author_rank: Regular Contributor
timestamp: May 15, 2018, 01:55:05 pm
content: I have a bunch of these armature driver in ear headphones that I have been repairing. Trying to figure out some things to rewire these with different high quality components. Could you look at the pictures and help me out? Trying to figure out if the low can benefit from a capacitor and if the sound will benefit from a different wiring scheme.https://imgur.com/a/z68LjHV
audio dac design question - Page 1
Forum section: electronics / beginners

author: Termanater13
author_rank: Newbie
timestamp: December 23, 2013, 07:45:52 pm
content: I'm looking to design an audio dac for use with an xbox and my computer. I know there are many options out there but non of them work the way I want. since I can't find one that will work I want to learn how to make my own. I have an idea on how it should work but I do not have any idea where to start, any ideas?here is what i have to start.I want 2-4 TOSLINK in and a way to make sure i an select which one i can hear.chat for the xbox via a 2.5 mm jack and a switch to make to change it to usb for pc use. I should be able to power it via that usb cable.finally a way to mix in an auxiliary source.I do realize that getting this done will take some time and may not work the way I want on the first attempt, but as, ong as im learning that will be fine.
Audio decoupling: Decouple the GND also? - Page 1
Forum section: electronics / beginners

author: PeteAU
author_rank: Contributor
timestamp: June 14, 2016, 12:37:22 pm
content: Hi All,Decoupling audio with a cap is pretty obvious, you want to block DC. But on some schematics and designs I've seen, people put a cap also on the AGND (the audio reference). What could this be good for?

author: rs20
author_rank: Super Contributor
timestamp: June 14, 2016, 01:42:22 pm
content: I've never seen this before. But, to be honest, if Ididsee non-negligible DC current flowing on an audio ground lead, that'd be a cause for concern, definitely not desirable, and blocking it with a cap would not be an unreasonable solution.It'd also be mandatory for any circuit where the local ground is expected to be tied to a non mains-earth potential.

author: macboy
author_rank: Super Contributor
timestamp: June 14, 2016, 02:01:52 pm
content: Those are coupling capacitors, not decoupling capacitors. Different name, different function.But to address the actual question, that is generally not a good idea. You need a solid, common ground reference. I'm guessing these are designs by amateurs found on the internet, not professionally designed products.

author: linux-works
author_rank: Super Contributor
timestamp: June 14, 2016, 02:25:05 pm
content: can't ever think of a valid reason to ADD caps to a ground return path. LOLnow, a ground BREAKER, maybe. example is when you want to 'link' earth ground (green wire on ac 3 wire IEC, for example) and electrical ground. a 10ohm and .01uF cap (or maybe .1, I would have to check) is often used as a ground breaker; so that at dc its not zero, but as you get up in freq, it shunts ac 'junk' to ground via the cap. there's also variations using back to back diodes so that if the voltage gets high enough, it 'switches' the current to gnd.none of that applies to this example you listed.someone must have just copied/pasted that. it makes no sense to me as-is.and if you need true ac coupling, you'd use a trafo so that you don't have a dc gnd path.
Audio Design Question - Page 1
Forum section: electronics / beginners

author: lovis
author_rank: Newbie
timestamp: December 12, 2024, 12:54:57 pm
content: I’m currently working on a project to create an adapter that connects a mobile network to a landline. I have an old rotary phone that I want to use on my desk. However, I don’t want to modify or destroy the internals of the phone. To achieve this, I’m using an interface board from Silvertel (AG1171).The Question:The mobile modem datasheet includes an audio reference design. From what I understand, the microphone and speaker signals are not referenced to ground. On the other hand, the AG1171 board requires a signal that is referenced to ground.Can somebody maby point me in the direction what i have search to find more information about something like this. Sorry if this is a really stupid question. ThanksI have some images of the reference designs

author: SteveThackery
author_rank: Super Contributor
timestamp: December 12, 2024, 05:36:00 pm
content: My background is in telecommunications, but I don't fully understand what you wish to achieve.Why would you want to connect a landline to the mobile network? And what do you mean by "connect"? Or do you mean you want to use an old rotary phone to make and receive calls on your mobile network? (In which case no landline will be involved.)

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: December 12, 2024, 10:12:58 pm
content: Hi lovis,welcome to the forum. :-)If you have a 611 or 612 (most common) it has probably a "Kohlemikrofon" (coal-corn-mic)and needs higher bias than the electret-condenser-mike in the app-note.To connect asymmetric source to the interface just ground the *_N-input.Use your search-engine for "Hybrid-transformer". ;-)Would be cool to have such a phone in the car, with the Original bell-ring. :-)))But the ringger needs higher voltage (AC) than 5 Volts.Be sure to report about you progress.Good luck

author: lovis
author_rank: Newbie
timestamp: May 08, 2025, 10:00:51 am
content: Hi! Sorry for the (very) delayed reply—life and studying got in the way, and I haven’t had time to work on the project until now.The reason I went down this whole rabbit hole was that I was trying to solve poor audio quality—not just from the microphone, but also from the speaker. After more troubleshooting, I discovered that the actual problem was high contact resistance in the off-hook switch (which makes sense, since the switch is about 70 years old!).I think I’ll need to rethink the architecture a bit going forward. This would require building a ringer circuit, which was previously handled by the onboard boost converter of the AG1171. Rather have a working phone then a not working originalIn any case, thanks so much for the answers!
Audio -> CV -> Audio conversion? - Page 1
Forum section: electronics / beginners

author: bleurgh
author_rank: Newbie
timestamp: November 24, 2020, 06:07:03 am
content: Hi I have some beginner-ish questions that are quite a bit beyond my current comprehension...Let's say I have a rasberry Pi based synthesiser with control voltage out and a headphone out...Is it possible to repurpose the CV out to send out audio in some way?What about if the audio waveform output by the synth was transcoded to voltage, sent out through the CV out and then transcoded back into a close approximation of the waveform with some external device?Is that what a FVC and VFC are meant to be able to do? And if so, can the FVC part be purely code based?

author: pwlps
author_rank: Frequent Contributor
timestamp: November 24, 2020, 07:44:27 am
content: VFC will convert a voltage to a single frequency signal. I wouldn't call it "audio"