hybridfree/eevblog-posts huggingface dataset:
Amp signal to swing between set values - Page 1
Forum section: electronics / projects

author: laejf
author_rank: Regular Contributor
timestamp: January 30, 2019, 09:35:28 pm
content: Hi. I'm wondering if there is any way of automatically amplifying an audio signal to vary between +-3.3V. I'm working on a signal sampling circuit and would like to increase the signal to noise ratio as much as i can. The problem is that i'm only able to use the circuit with an oscilloscope since the signal vary with the volume set on my computer and i need to adjust the resistance connected to an OP amp to keep it in the wanted interval. I'm guessing some sort of feedback could be involved by i cant come up with any and i dont know what to google for.The set interval of +-3.3V is the lowest voltage my sampling signal can go, it's a sawtooth-wave that a comparator compares against my audiosignal.How does a consumer level sampling circuit work? Does it sample the low level audio signal that can be as low as 10mV in my case? That has to introduce a lot of noise.Would be very glad for ideas! Thanks

author: Ian.M
author_rank: Super Contributor
timestamp: January 30, 2019, 10:13:06 pm
content: A keyword you may want to look up is: companderhttps://en.wikipedia.org/wiki/Companding

author: EmmanuelFaure
author_rank: Regular Contributor
timestamp: January 30, 2019, 11:02:08 pm
content: Yes :https://en.wikipedia.org/wiki/Automatic_gain_control

author: David Hess
author_rank: Super Contributor
timestamp: January 31, 2019, 12:21:10 am
content: An AGC (automatic gain control) loop comprising a detector, comparator, and gain control element can do that. This is a pretty common function.In your case the detector should measure the peak-to-peak value which is easy enough. The gain control element could be an operational transconductance amplifier or Gilbert cell multiplier.

author: SilverSolder
author_rank: Super Contributor
timestamp: January 31, 2019, 02:06:36 am
content: The circuit you are looking for might be called either an "Audio Compressor" or "Automatic Gain Control" (AGC) - you can google that and find tons of circuits on the Internet.

author: laejf
author_rank: Regular Contributor
timestamp: January 31, 2019, 09:23:12 am
content: Thank you! Now I can start somewhere. I will check up on this stuff and hopefully get it to work

author: Zero999
author_rank: Super Contributor
timestamp: January 31, 2019, 10:13:50 am
content: Yes an AGC is fairly easy to make. I investigated using an AGC on a project a year ago which was scrapped.https://www.eevblog.com/forum/projects/mic-pre-amp-circuit-discrete-or-ic/msg1410745/#msg1410745If it's digital and all you're doing is trying to get the best out of the ADC, then how about using a programmable gain stage to dynamically set the gain to the correct level?

author: laejf
author_rank: Regular Contributor
timestamp: January 31, 2019, 03:41:58 pm
content: For now it is not digital. But I will consider it!

author: laejf
author_rank: Regular Contributor
timestamp: January 31, 2019, 03:49:24 pm
content: It seems that automatic gain control is exactly what I was looking for. Thank you
Amplified speaker potentiometers (Treble and Bass) have slop in them. - Page 1
Forum section: electronics / projects

author: DW1961
author_rank: Frequent Contributor
timestamp: September 22, 2020, 05:55:01 pm
content: I'm wondering why some speaker pots (treble and bass) can move back and forth, that is, side to side movement, when other don't? Are the sloppy ones just cheap ass pots, or is there a reason for that (mounting, board placement, etc)?
Amplifier - Page 1
Forum section: electronics / projects

author: Jacktron
author_rank: Contributor
timestamp: September 09, 2024, 09:21:21 pm
content: I need an amplifier that can amplify the signal from a function generator to create an ac electromagnetic field in two pairs of helmholtz coilsany suggesetions? preferably something cheap

author: Zipdox
author_rank: Regular Contributor
timestamp: September 10, 2024, 01:30:49 pm
content: What frequency range are we talking about?

author: MK14
author_rank: Super Contributor
timestamp: September 10, 2024, 01:34:43 pm
content: They seem to keep on repeating threads, at least once. I think member(s), have decided to politely ask them to stick to this somewhat duplicate thread:https://www.eevblog.com/forum/projects/current-439435/msg5636807/#msg5636807
Amplifier DC protection/Power supply - Page 1
Forum section: electronics / projects

author: GamerAndds
author_rank: Regular Contributor
timestamp: December 01, 2014, 04:59:38 pm
content: I have these two circuits, one uses the dual voltage supply, while the other uses a single supply. Both are avaliable in the amp, one from the regulated circuit shown below. I am asking the question, firstly to know if any circuit is better than one another (any advantages, less headache), and secondly if anyone has any useful tips or ideas of filtering or stability changes for the power regulator shown. The two supply lines are +/- ~85 volts. 66,000 uF of caps on each side. I was also wondering if its better to put a extra transformer in there for the 12 V rail instead of regulating it?

author: richard.cs
author_rank: Super Contributor
timestamp: December 01, 2014, 05:06:26 pm
content: If your power transformer is torroidial then it would be easy to wind 10 turns (approx, some experimentation needed) through it for a low-power 12V auxiliary supply. It's nearly free and much simpler and more efficient than downregulating from 85 Volts. If it's E-I you might be able to fit them in but it's just a little more of a pain and you'll need a few more turns. You only need a hundred mA or so for the relay so the wire can be really thin.

author: GamerAndds
author_rank: Regular Contributor
timestamp: December 01, 2014, 05:29:04 pm
content: It is a toliroid however the way its mounted its almost impossible to wrap more turns on it. An additiional transformer is currently in it.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 01, 2014, 05:59:36 pm
content: Heck, you have enough voltage, a 120VAC relay would run fine here. You need a little more gain or level translation to use the first circuit.Speaking of, note the first circuit won't trigger if both channels do the same thing at the same time.Tim

author: GamerAndds
author_rank: Regular Contributor
timestamp: December 01, 2014, 06:56:12 pm
content: Thank you tim
Amplifier for gwinstek SFG2004 ? - Page 1
Forum section: electronics / projects

author: zen18
author_rank: Newbie
timestamp: January 19, 2020, 05:01:00 pm
content: HI to all !This is my first question to this forum and i really hope that someone can point me in right direction.I would like to create circuit that i can use as amplifier ( or some other solution ? ) and hook that to input of SFG 2004 function generator. The goal is to test different metal plates ( aluminum , copper ) and check the effect that is caused by generated frequency.Frequency range will be from 5HZ - 5KHZ and i was thinking to create some 100 - 150W amplifier.Problems and wishes:- how to apply this frequency to plate ( i think that speaker is the best solution, but i dont know if this would produce right effect ).- would it be possible to hook up some "electrodes" directly to plate and "bomb" the plate ?- if its not too much trouble to create, i would like to expand this frequency range to MHZ range. Question is, how much power would i need to make this work. BTW. planned carrier waves are sinusoidal and square waves.- at the time, i would like to start with lower frequency and power but in future, it would be nice to see how this would work in MHZ range ( at some resonance frequency ).OK. Your ideas and comments are more then welcome !Z.
Amplifier for using piezo knock sensor as microphone - Page 1
Forum section: electronics / projects

author: rvalente
author_rank: Frequent Contributor
timestamp: April 16, 2021, 09:19:07 pm
content: Hello mates,I'd like to make a small amplifier to use a automotive knock sensor as microphone and trigger my timing light (to check correct timing of diesel engines)What kind of amplifier should i use? Inverted single ended? Differential? Instrumentation? I've not found much literature about it..Attached a bosch knock sensor datasheet.greetings
Amplifier gain + single ended input - Page 1
Forum section: electronics / projects

author: Starlord
author_rank: Frequent Contributor
timestamp: June 07, 2015, 05:03:31 am
content: I've got a question about gain.http://www.ti.com/lit/ds/symlink/tpa3131d2.pdfLet's say I have a 0.5V peak signal (consumer line level) that I'm sending to the input of that amplifier.Using this calculator:http://www.sengpielaudio.com/calculator-amplification.htmI think that if I have that signal strength and a 12V supply, I need a minimum gain of 28db to take full advantage of it.Furthermore, I think that if I increased the supply voltage but I kept the gain and the signal strength the same, that the volume of my output wouldn't change.So, for example, if I wanted to allow up to a 24v supply, but I assumed that my input signal would never be more than 0.5v peak, I would need a minimum of 34db of gain if I wanted the volume to continue to increase all the way up to 24V.Is that correct?The second question I have is about single ended input. I want to connect a DAC to the amp. I have previously done so using this amplifier:http://www.ti.com/lit/ds/slos367d/slos367d.pdfOn p14, there's an example single ended input schematic which I used.The other amp states this though:"To use the TPA313xD2 with a single-ended source, ac ground the negative input through a capacitor equal in value to the input capacitor on positive and apply the audio source to either input. In a single-ended input application, the unused input should be ac grounded at the audio source instead of at the device input for best noise performance. For good transient performance, the impedance seen at each of the two differential inputs should be the same."That sounds similar, but why does one have the capacitor to ground on the negative side, and the other on the positive? Does it matter? And why does the smaller amp have special requirements for the size of the caps used there, but the larger amp seems to just want a 1uF?Also, what does it mean that the unused input should be ac grounded at the audio source instead of the device input? What would that be? A capacitor to ground on the negative wire of the line out of the device supplying the audio? Is that all? I'd think that would have to be directly connected to ground so the two devices would be at the same potential.

author: moffy
author_rank: Super Contributor
timestamp: June 09, 2015, 01:26:51 am
content: Quote from: Starlord on June 07, 2015, 05:03:31 amYes that is correct.

author: Starlord
author_rank: Frequent Contributor
timestamp: July 26, 2015, 11:54:59 am
content: Thanks!
amplifier help please - Page 1
Forum section: electronics / projects

author: Arlen moulton
author_rank: Regular Contributor
timestamp: November 16, 2014, 09:33:25 am
content: A few weeks ago i made a simple class a amplifier and it worked brilliantly and sounded excellent, a few days ago I built another one using a transistor of the same number and a potentiometer of the same resistance pluged it into my phone and like before it worked really well so then I took it out to the garage and pluged it into my CD player and a small round brown hole appeared in the Transistor any ideas why?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 16, 2014, 09:36:55 am
content: Probably the CD player wasn't AC coupled. Try a coupling capacitor to the base, 10uF or more should do.

author: kg4arn
author_rank: Unknown
timestamp: November 16, 2014, 01:00:01 pm
content: Your circuit is also at risk for thermal runaway. You may want to add an emitter resistor, Re, bypassed by another 10 uF capacitor. The resistor will provide negative feedback to the bias current as the tendency of the BJT to heat up causes the bias current to increase under a fixed bias voltage.You sometimes get away without some kind of negative feedback on the bias, if the current is low enough, but there is no guarantee that another transistor will behave the same.Also, if you are adjusting volume with the potentiometer, you are doing this by adjusting the bias current and the subsequent change in the transistor’s transconductance. You may want to set some limits by having fixed resistors on either side of the potentiometer.Some rules of thumb are:Pick the bias current you desire, IbPick Re such that 1V across it will give you that bias currentPick R2 about 10x Re at the mostPick R1 about 10x R2Pick R1 such that R2/(R1+R2) gives you about 1.7V at the base of the transistor.You can usually eyeball this and get it right.Or more precisely solve the simultaneous condition:Pick R2 such that R2/(R1+R2) gives you about 1.7V at the base of the transistorPick R1 Such that R1 || R2 is about 10x Re at the mostI attached an example. This is by no means the only way or the best way to build a class A amplifier, but it preserves your original architecture.

author: mikerj
author_rank: Super Contributor
timestamp: November 16, 2014, 01:49:38 pm
content: The other issue is the relatively high level of DC being applied to the driver. Not only will this cause undesirable heating, it will also bias the cone in one direction which at best will reduce the linearity of the driver.
Amplifier project - Page 1
Forum section: electronics / projects

author: Stinos
author_rank: Newbie
timestamp: March 15, 2021, 06:44:11 pm
content: Hi I'm Stijn and I am a first year electrical engineering student. Throughout the module im currently inI have learned how to analyze and make amplifiers. Now im trying to make my own amplifier for some arbitrary loadspeaker that is yet to come. For this speaker I will use two woofers of 4Ohms, 30Watt (rms) in parallel. I could use 8Ohm speakers such that my thevenin resistance is 4Ohms which is far more desirable. This however is not effiecient for me as I also want to power a tweeter (which is 4Ohms 30Watt rms) with a copy of my designed amplifier. This means im better of with an amplifier which can handle a 2Ohm load with an output voltage of 15.5Vpeak. If i succeed I can drive the two woofers of one amplifier and the tweeter from one amplifier and call it a day.The hard part is to create an amplifier that can handle this low output resistance (or impedance if you will). For the output stage I am using a class AB amplifier (or push-pull setup) to decrease the output resistance. My output resistance is still to high. Im looking for some tips to decrease the output resistance more or some general tips on my design so far as my nollege on this subject is still limited. I added a photo of my circuit to this post.

author: t1d
author_rank: Super Contributor
timestamp: March 15, 2021, 08:57:30 pm
content: This is not my area of expertise, but I wanted to welcome you to the forum! Wait, just a little more, and someone will help you. This is a great forum with generous participants.

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 15, 2021, 10:47:10 pm
content: I'm not sure there is a sence in so much stages. I guess they wan't help. And BC550/560 wan't work as a powerful driver for powerful output transistors. It has to be something much more powerful as drivers.(In general I think the whole design is wrong, but I'm not an amp designer so I don't wan't to say much about it).

author: Stinos
author_rank: Newbie
timestamp: March 16, 2021, 09:18:58 am
content: I used the bc550 as it was the main transistor used during my module. if someone has an idea of where to look for beter souted transistors for audio amplification I would be really gratefull. Furthermore the 3 common emitter stages are there to make the amplification as lineair as possible. Iknow the design is not a good one but thats why I try to find some advice here.
Amplifier stage for a GSM transmitter - Page 1
Forum section: electronics / projects

author: Micky
author_rank: Newbie
timestamp: October 13, 2015, 10:39:43 pm
content: Hi, I am a student of telecommunication systems, and I'm looking for some help about a school project.As disclaimer, keep in mind that in my country the law admit the ability to transmit on certain frequencies only if the output power is below 500 mW, and however my Professor, since this is a school project, allowed me to go further with this project (my Professor is also a radio amateur).Then, when I will submit/present this project, will be also present an examining committee; everyones, in fact, are aware of this device.So I don't aim to utilize this circuit for causing "malicious interferences" to other peoples: to avoid these unwanted interferences, moreover, I usually do my experiments in a shielded room, since the father of a schoolmate of mine, is the owner of a shielded lab. So everything is under a careful control.I also asked this question elsewhere, but I always prefer to listen advices from different people.Ok, this project is a wideband rf transmitter and is about the GSM vulnerabilities. In practice I made a wideband VCO (based on a POS-1060 VCO - datasheet:http://www.minicircuits.com/pdfs/POS-1060.pdf), which is modulated by a sawtooth signal generated by a 555 IC – the sawtooth signal goes from about 0.40 to 10 volt peak to peak -, then I add a DC signal from V2 – 15 volt, using a voltage divider which consists in a 5K trimmer.With the frequency counter, when I set the voltage divider trimmer to a value of 630 ohm, I can see an almost pretty linear signal which goes from 860 to 1000 Mhz (with a 9 centimeter antenna, at a distance of about 115 centimeters from the frequency counter). The following measurement is done without the gain stage, which is not present at the moment:Measurement with the frequency counter:http://s8.postimg.org/gs7jhcu51/Freq_Out.jpgSchematic:http://s13.postimg.org/rqo4tlx47/gsm_VCO.jpgNow I have to add the gain stage to the VCO output: to stay below the output power of 500 mW, I was thinking to implement an ERA-5 Monolithic Amplifier (datasheet:http://www.minicircuits.com/pdfs/ERA-5+.pdf).I calculated the value of C7 – 15pF; C8 – 15pF; C9 – 1nF; and R2 - 56 ohm, but I have some doubts: since I also implemented C6, I still need C9? The pin 3 of ERA-5 will be connected to a simple copper wire with a length of 9 centimeters: I still need C8? I also have some doubts about the value for the inductor L1; I was thinking of using a value of 100 nH, but I am not still sure of this value, or if for my needs the inductor is really necessary: I don't need to tune to any specific frequency (but in a wide range of frequencies); In the datasheet of ERA-5 I also read that L1 could be optional: why?. Can someone give me some hints and suggestions? Is it okay my solution? Or can I achieve the result with another/better method?Kind regards.
Amplifier transistor circuit (positive feedback) - Page 1
Forum section: electronics / projects

author: yalect
author_rank: Regular Contributor
timestamp: March 07, 2015, 02:22:35 pm
content: Hello,I would like to ask you if a capacitor connected between the collector and the Emitter of transistor can's work like positive feedback as shown on my attached circuit or that can’s decrease the output signal? if it doeshow it’s calculated?Thank you

author: Zero999
author_rank: Super Contributor
timestamp: March 08, 2015, 12:08:07 am
content: Why not simulate it in SPICE software and see?Just looking at it, I'd say not.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 08, 2015, 04:14:07 am
content: Yes, but only at radio frequencies. And it acts as a capacitive divider against base-emitter capacitance, which means the base should have some capacitance to ground, so the transistor acts somewhat like a common-base amplifier (regarding the feedback anyway).The usual purpose is making an oscillator with an operating frequency near the transistor fT.Tim

author: yalect
author_rank: Regular Contributor
timestamp: March 09, 2015, 02:44:31 pm
content: Hello, thank you for your replyYou said, the base should have some capacitance to ground, why? and can you explain more how it acts as a capacitive divider against base-emitter capacitance?Regards
Amplify and offset AC signal - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: April 19, 2014, 06:10:02 pm
content: Suppose you've got a small AC signal centred around 0V, and you want to amplify this signal a bit whilst also introducing a DC offset of +Vcc/2.The goal is to amplify and shift up the signal to Vcc/2 so that the entire waveform is always positive and in the 0-Vcc range so it can be sampled by a single-ended ADC, so that the minima of the signal is just above 0V and the maxima of the signal is just below Vcc, where Vcc is the voltage reference that will be used with the ADC, without using any negative power supplies for the opamp, using the simplest minimalist circuit.I've attached an example simple schematic as a starting point... but how would you do this differently, or improve it?

author: miceuz
author_rank: Frequent Contributor
timestamp: April 19, 2014, 06:39:04 pm
content: I'd buffer R5/R6 with another opamp. Then probably you will want to add a trimpot somewhere to trim out offset errors of opamps and resistor tolerances. And lastly your amplified signal does not fit into 3.3V.165e-3*10.1 + 3.3/2 = 3.315V and the opamp surely will never rail to 3.3V. You have to lower the gain.

author: LukeW
author_rank: Frequent Contributor
timestamp: April 19, 2014, 07:12:31 pm
content: Yeah, close enough. It was just a roughly guessed example value to illustrate the concept in question, obviously the gain can be fine tuned. And let's assume the opamp is rail-to-rail.

author: pmbrunelle
author_rank: Regular Contributor
timestamp: April 19, 2014, 07:24:33 pm
content: Quote from: miceuz on April 19, 2014, 06:39:04 pmNo point in buffering the R5/R6 divider if you're just going to tack on a 10k series resistance. Instead, replace R4 with a short, and increase R5 and R6 to 20k.

author: dannyf
author_rank: Super Contributor
timestamp: April 20, 2014, 02:09:56 am
content: QuoteReplace R5/R6 with a capacitor and call it a day.
Amplifying Color Carrier (Saturation) on CVBS signal. - Page 1
Forum section: electronics / projects

author: syntax333
author_rank: Regular Contributor
timestamp: March 28, 2019, 10:41:56 pm
content: Hi, I want to amplify only the saturation part of the CVBS signal as shown in attachment.Is there a circuit for this purpose only? or do I have to first high pass the CVBS then amplify and somehow add to the original signal?

author: Benta
author_rank: Super Contributor
timestamp: March 29, 2019, 12:18:55 am
content: Never heard of this demand before, and I'm convinced there's no IC available. This would normally be done by demodulating to RGB and doing colour processing from there.Can you shed a bit of light on the application? (I have a suspicion).

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 29, 2019, 01:44:16 am
content: Even back in the analog TV era, there was not a special IC for that purpose.You will have to separate the "C" (color) component from the "VBS" (vdeo, blanking, sync).Fortunately, that is relatively easy because the "C" component is a fixed-frequency carrier signal.For NTSC, the FSCis 3.579545MHz, and for PAL, it is 4.43362MHzSo, if you want to boost the saturation, you simply amplify the color subcarrier before you re-insert it into the CVBS.Your profile does not reveal where you are, but if you are in NTSC-land, you must be careful to avoid diddling the PHASE of the color subcarrier because that will affect the hue of the color. And even a slight change will produce a disturbing shift in color. But PAL is designed to be less sensitive since it reverses the phase of the FSCwith every line.Back in the day we used "processing amplifier" or "ProcAmp" gadgets. They would separately adjust all four parameters:1) "Brightness" ("pedestal" in the video terms or "offset" in electronic terms.)2) "Contrast" (luminance gain)3) "Hue" (color subcarrier phase)4) "Saturation" (color subcarrier amplitude/gain)There are still NTSC and PAL proc-amps available on Ebay And maybe even some still available new.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 29, 2019, 02:02:51 am
content: To do it properly, you will need a comb filter, as the sidebands of the chroma signal are "frequency interlaced" with the luma signal.In other words, the sidebands of the subcarrier modulated with the colour difference signals fall in the spectral "gaps" of the luma signal.You could "cheat" with an ordinary BPF, but there will still be artefacts from the luma signal in the recovered "chroma" from this, which could cause intermodulation.(Remember luma is full bandwidth).Probably demodulation of the colour difference signal & re modulating it on a chroma carrier is the least problematic way of doing this.The easiest way would be to look around & see if you can pick up some surplus analog Broadcast equipment designed to do the job.( It was something which was quite commonly done in Broadcasting).
Amplifying DAC output for lab PSU - Page 1
Forum section: electronics / projects

author: tbj
author_rank: Contributor
timestamp: May 10, 2015, 06:32:20 pm
content: Hi all.I've been following Dave's Lab PSU series of videos and I'm a bit stuck on the one where he shows how to convert the PSU to PWM control.I'm not sure if this was mentioned in the video or not (I couldn't find it), but let's say I have an output of 0-5v from my DAC. Now let's say my PSU needs to go 0-15v.What's the best way to linearly amplify the DAC output with a gain of 3?My current thinking is to use a non-inverting op amp in single supply configuration like so (simulated, works OK, no idea if this would work with real op-amps).But even with a rail-to-rail opamp, it won't be able to go all the way down to 0 volts, will it?Is there a better way?

author: bson
author_rank: Unknown
timestamp: May 10, 2015, 08:56:16 pm
content: Your DAC output likely won't be rail-to-rail either.Wire it up and see what happens!Edit: if the low end of the DAC gets too close to ground you'll need the bias the op amp input. This can be as simple as a pair of resistors. But measure it first.
Ampliifer 5ns rise time 300V p-p - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: August 19, 2021, 09:15:02 pm
content: How difficult would it be to design an amplifier capable of 5ns rise times with an output of 25V p-p, 100V p-p and 300V p-p?The output to drive an ultrasonic transducer over RG59

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 19, 2021, 09:24:05 pm
content: Hi,It is hard to do. If you just consider capacitance.I = C dv/dtdv/dt = 300 / 5E-9 = 6E10 V/sassume C= 10pFI = 10E-12 x 6E10 = 0.6A0.6A x 150V = 90 VAthat is a lot of current to drive just 10pF.Regards,Jay_Diddy_B

author: Marco
author_rank: Super Contributor
timestamp: August 19, 2021, 09:39:56 pm
content: Given the coax, presumably the piezo is 50 Ohm matched.So now you just have to make ~100 MHz 1kW class E amplifier.

author: Jester
author_rank: Frequent Contributor
timestamp: August 19, 2021, 09:48:20 pm
content: The existing system (not performing well, but working) is with amplifier that outputs 15Vp-p, 8ns rise time. Perhaps doubling to 30Vp-p might be a more realistic goal?

author: Marco
author_rank: Super Contributor
timestamp: August 19, 2021, 10:18:12 pm
content: Would a LMG1210EVM suffice? Or does it need to be a sinewave?

author: ejeffrey
author_rank: Super Contributor
timestamp: August 20, 2021, 03:41:48 am
content: Sin wave, square wave, or other? Fixed frequency or variable? How long is the cable and what is the piezo capacitance? How accurate does the amplitude have to be and what is your tolerance for reflections.If you just need a square wave drive mosfet switches will do this fairly easily. If you want a sine wave you can add an inductor to make the piezo resonant and make it much easier to drive.
amplitude gate - Page 1
Forum section: electronics / projects

author: ranch varment
author_rank: Regular Contributor
timestamp: June 19, 2015, 08:28:54 pm
content: Can someone please point to some example amplitude gate circuits? I tried to look it up, I found a barren wikipedia definition but I didnt see an actual circuit.Thanks.

author: N2IXK
author_rank: Frequent Contributor
timestamp: June 19, 2015, 09:33:44 pm
content: Window comparator to set the upper and lower bounds, driving an analog signal switch?

author: dom0
author_rank: Super Contributor
timestamp: June 19, 2015, 10:39:29 pm
content: Do you really need an amplitude gate, or do you actually need a noise gate?

author: ranch varment
author_rank: Regular Contributor
timestamp: June 20, 2015, 04:49:35 am
content: Its a precision compute, after I work out all my resistors, the signal I want is 1v, I want to gate off anything under .99v, (but its actually 0.x volts, depending on where it is, just always under 1.)I bet it would involve a transistor, like you said... but i want to do it without one...

author: dom0
author_rank: Super Contributor
timestamp: June 20, 2015, 08:38:47 am
content: So you want to discriminate a continuous signal into a binary signal? If so, a normal comparator is your friend.

author: ranch varment
author_rank: Regular Contributor
timestamp: June 20, 2015, 09:17:09 am
content: yeh. does that fix my problem if i have an approximate one, and i want a definite 1 as an output, because that would work for me as well.If I dont put it in my design, eventually my 0's get too close to my 1's, and eventually I have to pull a comparitor before its too late.Thankyou for the input - the normalizing comparitor definitely looks like the tool to use here. - as it works inverse as well.N2IXK sounds like he explained the whole in parts.
Amplitude Modulator / linear in voltage controlled Amplifier - Page 1
Forum section: electronics / projects

author: Andree Henkel
author_rank: Regular Contributor
timestamp: August 18, 2022, 01:05:49 pm
content: Hi, there. I´m thinking of designing a driver circuit for acusto optical modulators. Short AOM:https://en.wikipedia.org/wiki/Acousto-optic_modulatorBasic building blocks I guess: fractional PLL based XO, LC Bandpass, Amplitude modulation + On/Off Keying, Power Stage.I´m currently stuck at the amplitude Modulation:Analog Multiplier AD835 should work fine, but I would like to have somewhat higher max Bandwidth.All voltage controlled Amplifier IC I found are linear in dB, which is not what I need, I would need linear to control voltage.Any hints?

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 18, 2022, 01:12:50 pm
content: Have you considered a DDS with a microcontroller or FPGA driving a DAC?

author: RoGeorge
author_rank: Super Contributor
timestamp: August 18, 2022, 01:23:05 pm
content: I remember Bragg cells working at much lower frequencies. Why is it needed more than the max 250MHz of an AD835, what AOM model do you use?There are many ways to get AM, one of the most used topology for an analog multiplier is the Gilbert cell.

author: Andree Henkel
author_rank: Regular Contributor
timestamp: August 18, 2022, 01:27:47 pm
content: @NihaomikeDDS I considered, but XO + Bandpass is much less effort.I want to be able to do analog modulation by external signal. So the DAC in the DDS doesn´t help.

author: Andree Henkel
author_rank: Regular Contributor
timestamp: August 18, 2022, 01:39:02 pm
content: @RoGeorgeyeh, it´s probably best to go for it with AD835. And limit carrier to 250MHz. Modulation will be maybe 1MHz.In case I later move to higher carrier which I doub´t, maybe use a minicircuits part:https://www.minicircuits.com/WebStore/dashboard.html?model=ADE-1%2BDidn´t think of that.

author: dmendesf
author_rank: Frequent Contributor
timestamp: August 18, 2022, 01:53:13 pm
content: Ad834 goes to 500MHz.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 18, 2022, 02:02:16 pm
content: There were a few topics about AOM here, on EEVblog, but can not find them any more, Google search was broken this month, like they would have wiped out their indexes or something, don't know what's happening there.Could only find a couple of driver schematics:https://www.eevblog.com/forum/rf-microwave/designingbuilding-2w-rf-amplifier-for-40-5mhz-fixed-frequency-sinewave/

author: MasterT
author_rank: Frequent Contributor
timestamp: August 18, 2022, 02:24:10 pm
content: VCA824 710 MHz

author: Andree Henkel
author_rank: Regular Contributor
timestamp: August 19, 2022, 10:20:32 am
content: @Master T:thanks a lot, that´s exactly what Ì´m looking for.
Amplitude stabilisation of LC oscillators - Page 1
Forum section: electronics / projects

author: Achu
author_rank: Contributor
timestamp: September 10, 2020, 07:48:55 am
content: Like diode stabilisation and FET stabilisation in RC oscillators, what methods are used for the stabilisation of amplitude in LC oscillators? I have found it very difficult to obtain a clean sinewave in LTspice for Amateur radio purposes.
AMS AS3935 Lightning Emulator/Simulator  - Page 1
Forum section: electronics / projects

author: jpanhalt
author_rank: Super Contributor
timestamp: August 23, 2016, 09:13:28 am
content: A previous thread here (https://www.eevblog.com/forum/projects/generating-~500khz-pulses/msg259709/#msg259709) asked about the waveform used to simulate the lightning signature interpreted by the AMS AS3935 Franklin lightning detector. I have almost the same question and hope that now, 3 years later, someone may have looked at the output of the AS1504 (a DAC) used in the simulator.Here is a link to the product announcement for the evaluation board:http://ams.com/eng/Support/Demoboards/Wireless-Connectivity/Wireless-Sensor-Connectivity/AS3935-Demo-KitClick on the hot link to get the operation manual. The schematic, board, BOM are provided for the emulator, but not surprisingly, no code.A PIC24 MCU is used, which seems like overkill. My understanding of that schematic is that the MCU generates a PWM (?) signal that is converted to a voltage waveform by the AS1504, which in turn modulates the 500 kHz oscillator (LC+4 MOSFETS).Simply put, has anyone looked at that modulation? I have spent only an hour or so looking at lightning research , for example this:http://www.dtic.mil/dtic/tr/fulltext/u2/a234306.pdfFrom those studies, it is apparent that a simple spark won't work. One needs a more prolonged signature. Alternatively, has anyone been involved in lightning detection who can comment on what the modulation should look like?The critical problem will be to figure out what element(s) in the waveform give distance information, if it is not intensity.Regards, John
AMS1117 as a voltage reference - Page 1
Forum section: electronics / projects

author: VanitarNordic
author_rank: Frequent Contributor
timestamp: October 21, 2018, 04:02:17 pm
content: I read in the AMS1117 datasheet that it introduces 0.2% load regulation. Besides from the graphs, it shows a stable output voltage in front of temperature variances. By this way, it is better than some chips which are namely designed to be used as the voltage reference. is this correct or I missed some other parameters?

author: mvs
author_rank: Frequent Contributor
timestamp: October 21, 2018, 09:57:48 pm
content: AMS1117 has band-gap reference inside as many other Vrefs and Vregs... It is ok for general purpose things.For advanced applications you will definitely find better references.PS Load regulation is not so important for voltage reference. Load current in typical application is usually quite low and stable.Tempco, long-term stability, initial accuracy (if no calibration desired), noise, ripple rejection @ some frequency (PSRR) are more important parameters.

author: spec
author_rank: Frequent Contributor
timestamp: October 22, 2018, 12:07:51 am
content: + VanitarNordicIt was Interesting to read your OP about the performance of voltage regulators versus precision references. So I did the comparison table below, showing the AMS AMS1117-3V3 and Microchip MCP1501&-3V3 to see how they looked side by side.The chips are around the same price from first-tier suppliers. I used the latest AMS data sheet for the 1117 which seems less optimistic than the data sheet you quoted, but all the same the 1117 still came out well.The bottom line is that if you want a reasonably good, comparatively high output current, reference voltage go for the 1117. But if you can get by with a lower output current go for a dedicated voltage reference chip and get a much more accurate initial voltage and more stability.By the way, the 1501 data sheet is superior to the 1117. I had to extrapolate some of the figures for the 1117 from graphs and there was no indication that the graphs were typical, worst-case, or what! My impression is that the performance of the 1117, as a voltage reference, would vary quite a bit between individual devices. They are still great little voltage regulator chips though!

author: VanitarNordic
author_rank: Frequent Contributor
timestamp: October 22, 2018, 12:33:53 am
content: Quote from: spec on October 22, 2018, 12:07:51 amThank you. Actually, that was not my opinion. That was my assumption based on the information which I read, otherwise I asked if I missed something or if I am right or not

author: spec
author_rank: Frequent Contributor
timestamp: October 22, 2018, 08:58:47 am
content: No probsBy the way, OP = Original Post, not Opinion
AMS1117 short circuit protection - Page 1
Forum section: electronics / projects

author: brownt
author_rank: Regular Contributor
timestamp: July 10, 2018, 07:20:22 am
content: wondering about the short circuit protection on an AMS 1117 5 volt regulator.When short circuited, the current I suppose flows through the device, it then heats up, and then what. Does it melt eventually, or continually switch on and off as it reaches the thermal cut off point, or what happens?I mean where is the protection if it heats up and melts anyway?

author: bd139
author_rank: Super Contributor
timestamp: July 10, 2018, 07:43:41 am
content: Read the data sheet:The AMS1117 series of adjustable and fixed regulators are easy to use and are protected against short circuit and thermal overloads. Thermal protection circuitry will shut-down the regulator should the junction temperature exceed 165°C at the sense point.When it cools down the regulator will start up again so it will act as an oscillator with thermal feedback until the short condition is removed.

author: JS
author_rank: Frequent Contributor
timestamp: July 10, 2018, 09:59:51 am
content: Still not recommended to have the thermal shut down to go as normal operation port as reliability at those temps is quite lower.JS

author: wraper
author_rank: Unknown
timestamp: July 10, 2018, 10:02:32 am
content: Quote from: brownt on July 10, 2018, 07:20:22 amHow about reading a datasheet?

author: bd139
author_rank: Super Contributor
timestamp: July 10, 2018, 10:13:05 am
content: Quote from: JS on July 10, 2018, 09:59:51 amYes it'll blow up eventually but it's a slow failure rather than a catastrophic board burning death fireball.
AMS117 with 13.8VDC Supply - Page 1
Forum section: electronics / projects

author: @rt
author_rank: Super Contributor
timestamp: August 08, 2023, 11:24:00 pm
content: Hi GuysI have a project with dual supply (5 & 3.3V) provided by a couple of AMS117 devices.Max supply voltages for the devices is 15V and 12V respectively.I’ve seen a circuit where one AMS device was supplied with the output of anotherin order to meet specification, but it seems like a weak idea for efficiency.Would a few power diodes in series with the 3.3V regulator be a better idea?Or something else?Each supply powers an mcu, and there’s a few 5V stock logic chips.I’ve never measured the current draw of such a circuit, but I don’t imagine it couldapproach anywhere near 1A.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: August 08, 2023, 11:41:12 pm
content: Quote from: [member=98969]rt on August 08, 2023, 11:24:00 pmA problem there is short circuit can place the whole supply across one device.Most AMS1117 parts I can find are 15V and most clones are 18V, so 13.8V regulated should be just fine.

author: artag
author_rank: Super Contributor
timestamp: August 09, 2023, 12:22:56 am
content: If you're dropping (13.8 - 3.3) across a device and taking 1A, it might happily tolerate the input voltage but it will struggle to dissipate the 10W of heat.

author: Kim Christensen
author_rank: Super Contributor
timestamp: August 09, 2023, 12:36:46 am
content: Quote from: [member=98969]rt on August 08, 2023, 11:24:00 pmThe efficiency isn't going to be worse if you daisy chain the regulators. The same amount of power will be wasted if you didn't have to daisy chain. It'll just be split differently between the two regulators but the total power wasted as heat will be the same.

author: mikerj
author_rank: Super Contributor
timestamp: August 09, 2023, 07:54:39 am
content: The general advice when you have so much headroom is to not use LDO regulators. An LM317 will work nicely with no concerns of maximum voltage and no fussiness with capacitor ESR.

author: @rt
author_rank: Super Contributor
timestamp: August 09, 2023, 11:47:01 pm
content: Or I have considered mounting USB power ports on projects, which is basically handing the problem off to ChinaI was soldering last night under a USB powered magnifier ring lamp, using a car cig lighter adapter for USB power, which reminded me how cool these switching converters can run.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 10, 2023, 07:23:37 am
content: First, AMS1117 has three ones in it's number (you forgot one both in the subject title and in your text). Getting that right helps with online searches for datasheets and such.Putting linear voltage regulators in series is "not unusual". These days, mixed logic with 5V and 3V3 chips is quite common, and there are plenty of voltage regulators for which the maximum input voltage is 6V.Concerning "efficiency". Total heat to be dissipated with linear regulators = Voltage difference times current (which is generic formula for power) and the order does not matter.When your input voltage is that high, consider using an SMPS if you want efficiency.
AmScope eyepiece issue - Page 1
Forum section: electronics / projects

author: mkahky
author_rank: Newbie
timestamp: August 24, 2024, 11:08:38 am
content: I just bought an AmScope SM-3T. The eyepieces do not seem to fit snugly into the scope. In fact they barely rest into the edge of the ocular tubes. What could I be doing wrong?

author: jfiresto
author_rank: Frequent Contributor
timestamp: August 24, 2024, 02:40:31 pm
content: I have a pair of old Zeiss eyepieces that are ribbed to reach a 30mm outer diameter. I have to turn them to snug them up in eyepiece tubes that expect a smooth and constant 30mm diameter.Have you measured the O.D. of the eyepieces and I.D. of the tubes?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 24, 2024, 02:53:01 pm
content: On my Amscope (or clone) the eyepieces are mostly round tubes (with some lenses) that slide around 20mm into the tubes sticking out of the scope. It's a loose fit with around 0.5mm of play in it. I guess this is normal and it never bothered me.

author: zapta
author_rank: Super Contributor
timestamp: August 24, 2024, 05:12:34 pm
content: Same here, it's a loose fit and when I pull my had back after looking through the microscope, they often lift a little and fall back in place.I think it's normal, but if it's annoying, you can try inserting a piece of paper or something like that.

author: magic
author_rank: Super Contributor
timestamp: August 24, 2024, 06:05:36 pm
content: I would suggest a piece of something that doesn't shed particles. Insulating or teflon tape, aluminium foil, etc.
AMSRW-7812Z ambiguous pinout in datasheet - Page 1
Forum section: electronics / projects

author: ambrozy
author_rank: Contributor
timestamp: April 11, 2025, 07:41:45 pm
content: https://www.tme.eu/Document/ed4f5c1ec676dd1361949b693405bb15/AMSRW-78Z.pdfOn the second page it shows that printed face is the one to which pins are closer, but in reality printing is on the opposite side like on the photo of the regulator on the first page, any idea what is the correct pinout? I presume this is an error in the datasheet and real printing shows pin 1 correctly but I would rather prefer to be sure, the thing is expensive for a regulator, I don't want to fry it.

author: RoGeorge
author_rank: Super Contributor
timestamp: April 12, 2025, 07:02:55 am
content: I would expect the white dot to indicate pin 1 (+V input), no matter on which side would be the markings/print.
Amstrad IC2000 MKii Amplifier - Circuit Diagram - Page 1
Forum section: electronics / projects

author: laceypaul
author_rank: Newbie
timestamp: February 19, 2021, 07:23:04 pm
content: I've just uncovered my Amstrad IC2000 Mkii Amplifier in the loft. Does anyone have a circuit diagram? Can't seem to find one online!! Thanks

author: CJay
author_rank: Super Contributor
timestamp: February 19, 2021, 10:10:49 pm
content: Can't find one from a quick google (can find 200 Mk2 or 2000MK3) but you might find it if you can dig up an article index for Television Magazine or Trader Sheets...
An Academic Question, How Many Well-Known Topologies for DSB-SC AM Demodulation? - Page 1
Forum section: electronics / projects

author: KerimF
author_rank: Frequent Contributor
timestamp: August 23, 2024, 07:36:24 am
content: Hello,I mean, if a student who was graduated lately from a faculty of RF communications at a well-known university is asked the title’s question, what will be his answer?During my MS studies, more than 4 decades ago, there were two only: Costas Loop is based on PLL and uses I-Q signals. The squaring method uses a selective filter at 2*Fc to recover (after /2) the frequency and phase of the suppressed carrier (Fc).I ask you this question because I am not sure if, in these days, there are more universally known topologies or not. From where I live, searching on the internet is limited (restricted), due to world’s regulations. My search tells me there is no more!Thank you for your help and time.Kerim

author: KerimF
author_rank: Frequent Contributor
timestamp: August 26, 2024, 12:17:17 pm
content: By getting no reply, you tell me that the two topologies above are the only ones known at all universities around the world.Thank you.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 27, 2024, 07:19:59 am
content: Quote from: KerimF on August 23, 2024, 07:36:24 amTry searching from Tor browserhttps://www.torproject.org/download/, or connect through a VPN provider. Don't know about typical DSB-SC demodulators, only visited the topic to learn the answer.

author: KerimF
author_rank: Frequent Contributor
timestamp: August 27, 2024, 10:21:10 pm
content: Quote from: RoGeorge on August 27, 2024, 07:19:59 amThank you, Georges, for the hint.It happens that if I knock on the front door of a house and the door doesn't open, I just leave in peace even if the house has many unlocked windows {Mw 10:14}
An advanced smart house platform: FPiDroid House - Page 1
Forum section: electronics / projects

author: skorpyon1992
author_rank: Newbie
timestamp: April 21, 2015, 07:15:12 pm
content: Hello everyone, I am developing a project for Digilent Design Contest 2015 and I would like a few sugestions, ideas or opinion about my project: FPiDroid House.“FPiDroid House” represents a monitoring and control platform based on FPGA structures, embedded systems and web technologies. It provides the possibility to control multiple houses from one single web interface and the posibility to use existing devices, with minor changes. I made a few modules which controls the lighting system, the window blinds, alarm system, AC and heating system.For more details, you can see the instructable (with source codes) :http://instructables.com/id/FPiDroid-House-beta/I have to mention that the source code is not translated entirely, and I still have 1 minor bug to fix, but i will update the instructable then.And some youtube videos :Any suggestion or opinions? Thanks.