hybridfree/eevblog-posts huggingface dataset:
Analog guy needs help: Bluetooth DAC for audio - Page 1
Forum section: electronics / projects

author: Dabbo56
author_rank: Contributor
timestamp: October 01, 2022, 05:56:28 pm
content: I'm designing & building a 100 Watt class AB power amp which will be capable of taking a choice of analog inputs. While I'm at it, I would like to add the functionality of being able to play music from my iPhone via Bluetooth. I've spent an hour reading about DACs and CODECs and I'm out of my depth. One solution would be to buy a consumer DAC product and rip out its guts, but I'm hoping there is a more elegant way. So far I've been unable to locate a Bluetooth DAC board which can handle all the currently used CODECs. Help, anyone??

author: dietert1
author_rank: Super Contributor
timestamp: October 01, 2022, 06:37:36 pm
content: Searching ebay for "aptX bluetooth audio" i quickly found boards for US$ 20 to 30, that was easy.One needs to test some for support of codecs and sound quality. How to do that, one can read here:https://www.sereneaudio.com/blog/how-good-is-bluetooth-audio-at-its-bestRegards, Dieter

author: Buriedcode
author_rank: Super Contributor
timestamp: October 01, 2022, 06:39:22 pm
content: When you say "codecs" I assume you mean file encoding like AAC and MP3? Or do you mean the codecs Bluetooth uses, SBC, Apt-X etc.. ?Small Bluetooth dongles are pretty cheap, and you could permenantly place it inside your amp, or buy a small CSR bluetooth audio module:https://www.amazon.co.uk/Bluetooth-Receiver-Module-Stereo-Wireless/dp/B07ZZCH11LThese modules have the advantage that you can apply external power - rather than USB micro B, and just provide audio out. Some offer inputs for buttons for paly/pause/FF/RW etc.. Just be aware that some advertise as "lossless", there is no lossless codec for bluetooth.I've had success with CSR based modules, specifically CSR8645 and CSRA64215 based.

author: Dabbo56
author_rank: Contributor
timestamp: October 02, 2022, 01:35:55 am
content: Thanks Buriedcode, I’ve gone with the CSR module

author: Haenk
author_rank: Super Contributor
timestamp: October 04, 2022, 05:26:56 am
content: (keep in mind, these BT modules often output a very loud and annoying "melody" when powering up or connecting - check before implementation)

author: darkspr1te
author_rank: Frequent Contributor
timestamp: October 04, 2022, 06:22:47 am
content: You are not kidding about the annoying power up/connection "melody" , we recently purchased 10 boom boxes for class room use and half had a loud drum roll and the other had Chinese voice , theat was quickly solved by opening and pulling the eeprom , it then defaults to the chips factory but usable settings. not applicable to all devices though.darkspr1te
Analog High Definition Protocol - Page 1
Forum section: electronics / projects

author: SignalArray
author_rank: Contributor
timestamp: November 28, 2019, 04:37:59 pm
content: Does anyone know where to find signal specifications-voltage and timing for Analog High Definition used in security CCTV?I tried internet search and could only find that AHD is an open protocol. However, I'm unable to find any AHD specs like I can for other standards like HDMI.Some sources indicate AHD is an open standard.https://www.digitalsecuritymagazine.com/en/2015/06/16/ahd-tecnologia-analogica-de-alta-definicion-y-protocolo-abierto-de-nextchip/https://www.unifore.net/analog-surveillance/analog-hd-technologies-ahd-hdtvi-hdcvi-cchdtv-hdmdi.htmlI want to make my own decoder of the AHD cameras and use it for robotics. These cameras are high resolution and some cost only 10$.
analog logic of comprator based analog stabilier pulse circuit - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: October 11, 2024, 03:52:04 pm
content: Hello, I had a problem when my power supply produced +12V and -12V not at the same time a very slowly.The following circuit solves this problem like a magic producing +12 -12 pulse at simultaniosly.However this circuit cannot handle the ripple of my power supply(only 3%).Is there a way to increase the ability of the circuit to handle the ripple as shown below?LTspice file is attached.Thanks.

author: eutectique
author_rank: Frequent Contributor
timestamp: October 11, 2024, 03:58:23 pm
content: So, you've edited your original message, which makes my original question rather obscure.

author: john23
author_rank: Frequent Contributor
timestamp: October 11, 2024, 05:13:11 pm
content: Hello, I see reset ic definition ,How can i use it to create a pulse of 12V and -12V from my power supply input?Thanks.A reset IC is used mainly for monitoring the power supply voltage of electronic devices to monitor and detect whether the voltage drops below a threshold or exceeds a certain level.https://www.ablic.com/en/semicon/products/power-management-ic/voltage-detector-reset-ic/intro/#:~:text=A%20Reset%20IC%20(a%20voltage,or%20exceeds%20a%20certain%20level.
Analog multimeter + diode bridge - dual polarity current - Page 1
Forum section: electronics / projects

author: atferrari
author_rank: Frequent Contributor
timestamp: May 10, 2015, 02:58:36 pm
content: I am about to start testing some current sources. Output varies between -1000 mA and +1000 mA. Voltages involved: -5V / +5V.I will use an analog multimeter. To make it simpler and avoid damages (wrong polarity), I considered using a diode bridge.I need this not to be fast nor extremely precise, just to allow appreciating if for equivalent control voltages (measured with a DMM) the absolute value of the currents is in the ballpark.Not sure if the use of diodes requires kind of spectial additional precautions.Gracias for any suggestions.

author: Kleinstein
author_rank: Super Contributor
timestamp: May 10, 2015, 03:36:49 pm
content: With the extra diode the source sees the extra voltage drop of about 1.5 volts. At very low currents just around 0 (so that noise includes 0) this may give a slightly different reading - a parallel cap of maybe 100 nF or so might help. Otherwise the selection of diodes is not critical - something like a bridge rectifier should work.Analog meters are usually not that sensitive - so even full scale (or even 2-5 times more) signal in the wrong polarity will not damage the meter. Usually they are protected so they can withstand the same current or voltage in both direction. How much is usually stated in the manual - this can vary substantially in between ranges and models.

author: atferrari
author_rank: Frequent Contributor
timestamp: May 10, 2015, 03:40:03 pm
content: Quote from: Kleinstein on May 10, 2015, 03:36:49 pmThanks for replying.
Analog multiplexing capacitive sensors - Page 1
Forum section: electronics / projects

author: pyrohaz
author_rank: Regular Contributor
timestamp: June 22, 2014, 10:33:30 pm
content: Hi,I've got a fair number of pads that I want to be able to sense capacitively and I'm wondering if I can multiplex them using a standard 4067 IC? I'm using the IQS228 IC for my sensing though I'm sure most 1 channel sensors would work?I've included a small schematic of my idea too. The capacitive sensors are multiplexed to the IQS228 IC though the 4067 chip and the channel of the 4067 chip is controlled by the microcontroller. The output of the IQS228 is also sent to a digital input of the microcontroller. Could anybody enlighten me on whether or not this would work?Thanks,Harris

author: dannyf
author_rank: Super Contributor
timestamp: June 23, 2014, 12:29:19 am
content: What kind of input signal does the cap sensing chip require?

author: pyrohaz
author_rank: Regular Contributor
timestamp: June 23, 2014, 06:04:19 am
content: According to the datasheet for the IQS228, its some form of (assumed pulse) waveform, biased some voltage above 0v. The main problem I'm thinking about is whether the multiplexer capacitance will pose any large problem? Its quite likely that the capacitance posed by the multiplexer will be relatively constant so hopefully the initial calibration could eradicate this problem.Any ideas?Harris

author: jmole
author_rank: Regular Contributor
timestamp: June 28, 2014, 12:43:59 am
content: You should check out the new Cypress PSoC 4200, they're on sale for $1/unit until september something, and can do capsense on any GPIO on the chip. Probably cheaper than the mux solution.

author: pyrohaz
author_rank: Regular Contributor
timestamp: July 08, 2014, 05:55:41 pm
content: Thank you all for your replies!In the end I decided to use multiplexers and design my own discreet solution implementing a digital timer and capacitor dependant oscillator.Thanks again, Harris
Analog multiplier with Hall effect sensor - Page 1
Forum section: electronics / projects

author: rodolfok
author_rank: Contributor
timestamp: March 28, 2018, 11:00:51 pm
content: I am looking for information on Hall effect applications for the realization of an analog multiplier. In literature there are several rather dated patents that use the Hall effect to multiply, for example, two currents. Searching among the various sensors available on the market, however, I found that these are designed primarily to be used as a latch or in a linear way, but using as the only variable the variation of magnetic flux and not, as necessary in a multiplier, also the variation of the biasing current of the Hall element, which is therefore practically fixed by a supply voltage which, although variable, is often regulated inside the chip which makes up the sensor, for which it can not be used as a second variable.The attached file is a USA patent from 1964.Could someone direct me to a more recent literature or to Hall effect devices that realize these characteristics?http://cloud.tapatalk.com/s/5abc1e6e749b2/US3121788_Hall_effect_multiplier.pdfInviato dal mio SM-G903F utilizzando Tapatalk
Analog output using a current-output DAC and resistors - Page 1
Forum section: electronics / projects

author: pugglewuggle
author_rank: Contributor
timestamp: April 21, 2014, 08:25:41 pm
content: Does it make sense to have a 4-20mA output DAC and use a precision (~1%) load resistor to convert this to a voltage output with the goal of having a selectable current/voltage analog output? For example, a 250 ohm resistor to give a 5V, a 500 ohm to give a 10V, etc.? Is this a bad practice to do the potential non-linearity of the resistor and lack of temperature compensation in the passives or is it okay? I know there are many chips that do this internally such as the Analog AD5755 but it is a lot more expensive (3 times as much $ per channel). Thoughts?

author: ajb
author_rank: Super Contributor
timestamp: April 22, 2014, 03:33:24 am
content: It's a fairly common technique in industrial control equipment to allow a single analog input to read a current- or voltage-output sensor. Typically the resistor is added at the input, because if you've already got a current loop driver you may as well run a current loop all the way to the receiver.Whether or not the error potential is a problem depends on the precision required by your application. Also note that a single resistor with a 4-20mA output means you won't get a 0-5V output, but rather a 1-5V output, so you lose the bottom 20% of your range. That's potentially a bigger problem since it means a substantial loss of precision.

author: pugglewuggle
author_rank: Contributor
timestamp: April 22, 2014, 04:45:49 pm
content: I am looking to output a temperature-stable linear signal in either current (4-20) or voltage... does it make sense to do this with a current-source DAC and a resistor or a dedicated IC that can do either?

author: David Hess
author_rank: Super Contributor
timestamp: April 22, 2014, 05:37:44 pm
content: The current output DACs that I am familiar with do not extend to 20 milliamps and only bipolar current switched ones support a high compliance voltage. CMOS current output DACs rely on a minimum output offset voltage for accuracy in current output mode.
Analog PWM triangle wave question--why does it work? - Page 1
Forum section: electronics / projects

author: IanB
author_rank: Super Contributor
timestamp: February 15, 2012, 07:46:13 am
content: So I'm watching the YouTube video by Hugoneus here:In this video he demonstrates the generation of a triangle wave by integrating a square wave with an op amp. In theory this is nice (and apparently in practice too, if the video is to be believed).But a question is puzzling me. What prevents the integrating op amp from integrating a constant offset voltage and making the triangle wave drift up or down until it clips at one of the extremes? Evidently the wave seems to remain centered around zero, which makes me think there is some kind of negative feedback that prevents drift. But what is it? Why does the circuit work?(I am thinking it might be the resistor placed in parallel with the feedback capacitor in the integrator?)

author: Rerouter
author_rank: Super Contributor
timestamp: February 15, 2012, 07:51:22 am
content: try changing the values of the integrator, it will clip easily, integrators are only good for small ranges, and amplitude falls as you increase frequency, this is why most function generators use a range switch, in powers of 10, any more and the amplitude would begin to seriously decrease,personally been chasing how to get a sine integrators amplitude to stay stable over 10-4000Hz without range switches,

author: IanB
author_rank: Super Contributor
timestamp: February 15, 2012, 07:54:58 am
content: No, not clip, drift.When you build an analog integrator and leave it running, it is integrating the input for an indefinite and unlimited amount of time. If the average value of the input signal is not exactly zero the integrator will be integrating a positive or negative constant. Since in reality there is always some source of non-zero offset the integrator should drift up or drift down and eventually go off scale. Why doesn't it?

author: ejeffrey
author_rank: Super Contributor
timestamp: February 15, 2012, 08:44:52 am
content: Because integrators are usually designed with a low-frequency cutoff exactly to prevent this problem. A large value resistor in parallel with the integrating capacitor gives the circuit a finite gain at DC.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 15, 2012, 09:03:39 am
content: The resistor R2 in the feedback loop of the integrator allows a path for DC to flow. Without it, the integrator topology is susceptible to instability since a capacitor looks like an open at DC.Shahriar's transfer f'n shown in green is a simplification of what's really happening; note the "for w >> 1/RC" caveat. If you work out the proper transfer f'n of the integrator, you'll discover that the filter stage is theoretically stable for all omega.
Analog scope in X-Y mode - Page 1
Forum section: electronics / projects

author: atferrari
author_rank: Frequent Contributor
timestamp: April 09, 2015, 10:28:18 am
content: Analog oscilloscope in X-Y mode.I am not sure how to quantify this based on the scope bandwith, 5 MHz:I locate the beam inside a grid of 200x200 values by applying any of 200 possible steps (0 to +3V range) to each axis.Beam initially located at (50,50). My questions:a) How long it will take to get the beam at (150,150)?b) How long to reach 0,150?c) How long to reach 150,0?d) How long for the three cases above if I start at (0,0)?I do not have my analog scope with me right now but spent some time wondering how could I actually measure this by myself. (I am affraid it is way too abvious).

author: penfold
author_rank: Frequent Contributor
timestamp: April 09, 2015, 12:21:09 pm
content: I'll assume that the channel bandwidth is the limiting factor. If you set the position as a square wave then the position will follow an exponential decay towards the final position. A 20 MHz (with 3 dB point at 20 MHz that is) scope should have the point in position within 30 ns (a few time constants at 20 MHz).

author: macboy
author_rank: Super Contributor
timestamp: April 09, 2015, 03:59:22 pm
content: Quote from: penfold on April 09, 2015, 12:21:09 pmUnfortunately, the horizontal bandwidth (X input) is usually much lower than the vertical bandwidth.If you have a function generator, you can connect both X and Y to the same sine wave signal. Start at about 1 kHz. With the right settings on the scope this will give you a straight diagonal line. Increase frequency until the line is not longer straight or becomes shorter or more vertical. You are observing the horizontal bandwidth limit. You may also see the line open up into a oval; this would be caused by low bandwidth X channel introducing a phase shift that is not equal to the higher bandwidth Y channel.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 10, 2015, 02:42:48 am
content: t_r ~= 0.35 / BW, so expect around 70ns risetime for 5MHz BW.As long as the scope is linear, it will have the same settling time (to within a given percentage of input step) for any number of divisions in the input step.The settling time to within a fixed (absolute) position will be approximately logarithmic with the number of divisions traveled, i.e., settling to within +/-1 div from 100 away will take a few t_r's, while settling within +/-1 div from 2 div away will only take about t_r/2 (since it only has to settle by 50% of the input step).Tim

author: atferrari
author_rank: Frequent Contributor
timestamp: April 10, 2015, 09:44:11 am
content: Quote from: macboy on April 09, 2015, 03:59:22 pmIt makes sense. You do not need them to have he same. Now I started to udnerstand things.

author: atferrari
author_rank: Frequent Contributor
timestamp: April 10, 2015, 09:46:05 am
content: Quote from: T3sl4co1l on April 10, 2015, 02:42:48 amConsidering my proposed shiftings analogous to step functions helps to understand what to expect.Gracias Tim.
Analog scope - On-screen text - Page 1
Forum section: electronics / projects

author: atferrari
author_rank: Frequent Contributor
timestamp: April 28, 2015, 08:03:32 pm
content: I've reworked the whole code of an old project of mine from August 2009.The results are shown in the video which happens to be my very first in life.Critics of any kind are kindly requested and will be appreciated.https://youtu.be/3GTnXEb-JmcToday I feel happy.

author: c4757p
author_rank: Super Contributor
timestamp: April 28, 2015, 08:14:54 pm
content: Funny, I think that looks nicer than most analog scope readouts I've seen (lots of higher-end analog scopes had some digital readout capability).

author: GK
author_rank: Super Contributor
timestamp: April 29, 2015, 12:45:00 am
content: Neat, but I think you took the easy route doing it with a uChttp://www.glensstuff.com/fouriersynthchargen/fouriersynthchargen.htm

author: N2IXK
author_rank: Frequent Contributor
timestamp: April 29, 2015, 01:42:55 am
content: Quote from: c4757p on April 28, 2015, 08:14:54 pmThat's probably because the the text is the only thing being written, as opposed to text vectors being multiplexed in during the retrace blanking period while one or more analog waveforms are being displayed on the same tube. Remember, an analog scope isn't a raster scan display like a TV or computer. On scopes like the Tek 7000 series, there are always artifacts introduced into both the text and the waveforms by the multiplexing.

author: atferrari
author_rank: Frequent Contributor
timestamp: April 29, 2015, 01:34:22 pm
content: A closer look with nonsensical text for tests.
Analog Signal-Data Acquisition System  - Page 1
Forum section: electronics / projects

author: cRash1001
author_rank: Contributor
timestamp: March 31, 2016, 04:04:13 pm
content: An analog sensor's output may be 0-5 VDC, 0-10 VDC, +/-5 VDC, +/-10 VDC, 0-20mA or 4-20mA. I want an IC wit 8 Channels each of which can be progammable for any one of the standard input ranges(0 to 5V, 0 to 10V, ±5V, or ±10V). The IC should be atleast 16 bits or more. So, guys any ideas?

author: Vgkid
author_rank: Super Contributor
timestamp: March 31, 2016, 05:45:17 pm
content: What about using a mcu with a multiplexed adc. That way you can get 16 bits and however many channels you need. The ads1115 is a 16bit 4ch adc.

author: Marco
author_rank: Super Contributor
timestamp: April 01, 2016, 12:08:30 am
content: An 8 channel ADC with a PGA almost gets you there, but it can't switch in the resistor for the current. You'll need the ADC, 1 resistor and a mosfet.
Analog signals and PCB routing  - Page 1
Forum section: electronics / projects

author: gogoman
author_rank: Regular Contributor
timestamp: January 10, 2021, 07:05:37 pm
content: hello on the PCB are analog signal pairs which feed the input of a instrumentation amplifier (INA). The overall trace length from source to INA is several inches.The INA converts the differential pair to single ended. The signal bandwidth is ~200khz with voltage range of 0 to 1.5V.Does the 2" length pose a problem or is it better to place the INA closer to the source.From a PCB prospective is there a recommended best practices for routing the pair, track spacing, track width and surrounding copper pour.thanks

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 14, 2021, 09:39:34 am
content: The differential pair is certainly more resistant to interference. I would shift the op-amp closer to the consumer in your case. But the conditions you specified are not very strict, although you did not specify the environment in which the board will be located. However, I think you can be quite free in these parameters.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 14, 2021, 09:53:20 am
content: Such length itself isn't a problem at all.Everything else is of higher interest; opamp BW (not signal BW), how the signals are routed, grounding, what else is on the PCB and where, and so on.

author: KT88
author_rank: Frequent Contributor
timestamp: January 14, 2021, 10:05:04 am
content: Having shorter traces is always desirable, but not always possible. The main challenge or potential source of failure is to create diferent parasitic impedances against ambient. This would result in mode conversion - the common mode disturbancese won't cancel out anymore completely. Another source of error could be an uneven amount of parasitic thermo couples that could even be at (slightly) different temperatures. That would create a more or less significant offset that changes over time and ambient temperature. The length of the traces itself is in your case no issue.CheersAndreas

author: Marchewa
author_rank: Newbie
timestamp: January 16, 2021, 12:17:43 am
content: Well, if you are very picky you can think of it in this way:Its better to place amplifier closer to source of signal, couse you can pick up something (some signal) before it gets there and than you are amplifying signal + noise you picked up. You want to reduce noise to minimum before amplifier.Still, you will rarely see the difference.sorry for bad Englishedit. Its differential pair so it may be different. Hard to tell.

author: gogoman
author_rank: Regular Contributor
timestamp: January 17, 2021, 03:41:04 pm
content: The analog signals are routed under several motor traces and are perpendicular to these traces. The INA would then remove the differential noise (I hope).Btw a ground is between the motor and analog ground.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 17, 2021, 04:05:11 pm
content: A perpendicular intersection, and even at a distance of 1.6 mm (the thickness of the board) will have a very small impact, do not worry about it.
Analog sorting network - Page 1
Forum section: electronics / projects

author: mathsquid
author_rank: Frequent Contributor
timestamp: June 13, 2025, 06:44:43 pm
content: I recently learned about sorting networks, and decided to build one out of comparators and relays that would take in four voltages and sort them from lowest to highest. Here's the result, in case anyone else finds it interesting.In this video three voltages are held constant and the fourth is a triangle wave. Lots of clicky relay goodness.

author: LaserSteve
author_rank: Super Contributor
timestamp: June 16, 2025, 03:15:22 pm
content: Are you going to post a schematic?Steve
analog switch off isolation difference between single ended and differential sw? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: June 03, 2014, 02:08:53 am
content: http://www.analog.com/static/imported-files/data_sheets/ADG5206_5207.pdfThe ADG5206 is a 16:1 mux, the ADG5207 is a 8:1 differential mux.I am interested in nice off isolation specs, I noticed that the ADG5207 has 10db more off isolation, and this is nice. How come the off isolation is 10dB better on it? Is it ok to use the 5207 for single ended signals to take advantage of the higher off isolation (leave half of it floating). I only need 5 switches but I chose this part because it has way better off isolation then anything else I could find (typically the other parts are like 20 dB less at the frequency that I am interested in. I figure I would use s1, 4, 8... skip some switches to get lower crosstalkDoes this increase in off isolation have something to do with the differential signal or is it just built differently?or I think I can put two switches in series to really get that off isolation up.

author: moffy
author_rank: Super Contributor
timestamp: June 04, 2014, 01:22:16 am
content: It is because it switches both the + and - path that you get the extra isolation. If you put the + and - path (excuse the abreviation I realise its ac) in series you should get the same isolation i.e. you are putting 2 switches in series. The feedthrough is due to parasitic capacitance across the switching devices, so if you load the outputs of the switches with R and or C you can significantly improve the off isolation.
Analog switch suggestion - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: January 07, 2020, 08:19:43 am
content: Hi,For switching two -+ 5V signals to an ADC input, I should use an analog switch, I have a board with the TS5A3160 part on it,I want to know if you know some part with this foot print to be able to accept -+5V as analog signal, any suggestions?

author: moffy
author_rank: Super Contributor
timestamp: January 09, 2020, 04:08:42 am
content: The TS12A4516 & TS12A4517 use up to +/-6v supplies and could be suitable.

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: January 09, 2020, 06:10:13 am
content: Thanks moffy
Analog Switch to Control Low Voltage AC? - Page 1
Forum section: electronics / projects

author: petersanch
author_rank: Regular Contributor
timestamp: June 15, 2021, 10:10:26 am
content: I have 2 audio amplifiers with output voltages between +10V and -10V. I want to make a digitally controlled switch to control which amplifier is driving the speaker.The clear choice is a relay for this but I want to do this using FETs if possible to take up little space on the pcb and be inexpensive. I also want the amplifier output to remain as unattenuated as possible.I found this circuit that uses a p channel and n channel to make an analog switchI can see this working for positive voltages, but will this be able to control the negative voltages from the amplifiers? Is there a better option for this?Cheers!

author: Kleinstein
author_rank: Super Contributor
timestamp: June 15, 2021, 12:18:38 pm
content: The CMOS switches are usually relatively high in resistance (e.g. 50 Ohms range) this is not really practical for a low impedance (e.g. 4 or 8 Ohms) load.The more practical way is to to have only 1 amplifier and do the switching at the amplifiers input side. Than CMOS switches are a very pratical solution.If really lower resistance FET swtiching is needed, it would be more the Photo-mos / electronic relais with MOSFET output. Some are relatively low impedance, maybe around 1 Ohms. If needed one can use 2 MOSFETs and a photovoltaic optocoupler to drive the gates. It may not be smaller of lower cost than a relais.

author: David Hess
author_rank: Super Contributor
timestamp: June 15, 2021, 05:21:23 pm
content: Almost all discrete power MOSFETs include the body diode between their drain and source, so they would need to be used in pairs for a total of 4 power MOSFETs per switch.Solid state relays which use a pair of power MOSFETs in series to isolate their body diodes and have floating drive could work, and you can make one using a photovoltaic optocoupler and a pair of power MOSFETs. 4 MOSFETs are not required because the gate drive signal is isolated. This method also does not require supply voltages greater than the voltages to be switched.
Analog switch: With separate substrate, what potential is the D-S circuit at? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: November 17, 2019, 02:22:21 pm
content: I've been reading MT-088 "Analog Switches and Multiplexers Basics". This shows separate source & substrate connections. The paper statesQuoteGiven the above, and thinking only about the NMOS half of the switch, then when the device is ON, the substrate is at -15V and the gate at "Vdd" (say +15v). The channel is "inverted" and acts as a resistor.Suppose weexplicity reference Vds to substrateby using a wire link from substrate to source. Then I wouldexpect the usual limits about Vd to apply: I cannot allow Vd to be above one Vthreshold of VGate.Now, suppose we againdisconnectsource from substrate and apply a "floating" 1v5 coin cell (positive to drain, negative to source), and assume the resulting current is within safe limits. We have forcedVd > Vsbut where does that entire voltage span (Vs...Vd) lie WRT substrate? We have not explicity made any effort to reference it to VGS in any way. Thus, I do not understand whether there would be a Vds limit (due to channel pinch-off).
analog switch - Page 1
Forum section: electronics / projects

author: Mitalius
author_rank: Contributor
timestamp: May 18, 2019, 03:19:01 am
content: I have a 2.5V DAC with two channels.I invert one of these with OpAmp.So I get:Channel A: 0V to 2.5VChannel B: -2.5V to 0VI would like to have an output on which I can switch these 2 channels at a frequency of 0.5MHz.I plan to use this to generate a signal for a current source.Now I use TS12A12511 analog switch to switch DAC channels, but it is very noisy.It is very important for me to have a good signal quality, but I can't figure out what else to do.

author: OwO
author_rank: Super Contributor
timestamp: May 18, 2019, 03:35:31 am
content: SGM3157BL1551

author: OwO
author_rank: Super Contributor
timestamp: May 18, 2019, 03:37:37 am
content: Noisy during steady state or while switching? Can you try stopping the switching action and see if the noise persists? What kind of noise? harmonics of the switching frequency or just white noise?

author: OM222O
author_rank: Frequent Contributor
timestamp: May 18, 2019, 04:20:39 am
content: a slim fit relay is pretty analogit's less than ideal but provides 0 noise. also if you get the type that only needs current to switch and then latches mechanically, it probably consumes less power than a chip that's constantly powered on as well.

author: Kleinstein
author_rank: Super Contributor
timestamp: May 18, 2019, 07:07:04 am
content: The CMOS switches mentioned so far are very low resistance. This usually comes with a relatively high charge injection. During switching here will be a charge pules going out from the switch. This could effect the DAC or inverting amplifier. Depending one the DAC signal bandwidth one could have a filter / ferrite there to avoid at least the very high frequency part.Another point is going for a higher impedance and possibly slower switch. So something like 74HC4053 (maybe single gate version of this).

author: David Hess
author_rank: Super Contributor
timestamp: May 19, 2019, 11:40:49 pm
content: Start by lowering the impedance of the analog signals at the input of the analog switch which will absorb more of the charge injection. An easy way to do this is to use operational amplifiers which can drive a capacitive load as a buffer.If you want a much higher performance circuit, then look at using currents instead of voltages and switching using a diode bridge like discrete function generators work.

author: Mitalius
author_rank: Contributor
timestamp: May 27, 2019, 08:32:41 am
content: Quote from: OwO on May 18, 2019, 03:37:37 amNoise during switching, 0.5MHz.I see outliers during every channel switch.Unfortunately, now I have no fee and I can not show the photo oscillogram

author: Mitalius
author_rank: Contributor
timestamp: May 27, 2019, 08:34:45 am
content: Quote from: OwO on May 18, 2019, 03:35:31 amBut I also have negative voltages.These switches do not fit
Analog switches for volt meter range switching - Page 1
Forum section: electronics / projects

author: leonerd
author_rank: Regular Contributor
timestamp: July 21, 2017, 11:45:52 am
content: Hi all,Dredging up an old topic, but I foundthis poston precision resistor networks used as range switches in volt meters yesterday and it exactly answers about 4 different questions I had all in one. But it leaves me with some more.Lets consider current flow for a moment. Looking again at the 1V input, with the range switch set to the lowest divide ratio of 10:1, that 1V is flowing through a total resistance of 11.111...Mohm. I make that a current flow of 90nA. What sort of analog switch chip are you going to use for that?I see "leakage current" of channels specified sometimes in units of nA already (e.g. the randomly-picked MAX351 guarantees to source or sink no more than 0.4nA, which is 0.4% of our signal here). Does that matter? I admit I don't quite understand what the leakage current is measuring, and whether it's important in this application.Given our switch is shorting a resistor to the low-impedance ground supply, I don't think charge-injection is an important parameter here, as ground will conduct that all away.Channel resistance is fairly important, at least at the highest end of the divider chain - a 10ohm channel on that 1K resistor is a massive 1% of error. Maybe on higher ratio / lower resistance end of the chain we'd be better off using discrete FETs instead of an analog switch part?Can someone suggest a suitable analog switch we could use for precision voltage measurements based on this sort of divider?

author: Kalvin
author_rank: Super Contributor
timestamp: July 21, 2017, 02:43:57 pm
content: You can use discrete MOSFETs and handpick/screen those which perform best. You should be able to find some parts achieving very low leakage current of 10pA and better quite easily. For example this JFEThttps://www.digchip.com/datasheets/parts/datasheet/513/SST4118-pdf.phphas leakage below 1pA at 25 C. Typically leakage current is specified at 25 C, and it will increase considerably at higher temperatures. There are matched MOSFETs, for examplehttp://www.aldinc.com/pdf/ALD110808.pdfand others with datasheet specifying typical leakage current of 10 pA, but handpicking suitable devices your should be able to find parts with sub-pA currents.
Analog switching thermocouple level voltages? - Page 1
Forum section: electronics / projects

author: Mazo
author_rank: Regular Contributor
timestamp: November 28, 2022, 08:17:27 pm
content: Hi,I am in a need of 6-8 thermocouples measuring circuit(type K if it matters),optimized for BOM savings.Accuracy wise anything <10degC is good enough,and even worse on temps lower than 200-300deg C.I just thought about the idea of switching them before the amplifier,and so far I don't see any glaring problem.Am I missing something obvious?

author: Kleinstein
author_rank: Super Contributor
timestamp: November 28, 2022, 08:25:16 pm
content: CMOS switch chips are quite good switching even small voltages. For low cost even the HEF4051 or 74HC4051 are OK. If there are little thermal gradients on the board they are good for sub µV voltages.An important point with CMOS switches is that they usually only work for voltage inside there supply and a tiny bit (e.g. 100 mV) outside. They also need some protection - especially the old ones are suceptible to latch up from voltage outside the supply.With multiple thermocouples one should first have a cold junction block to bring all the wires to copper and only switch after that.

author: mag_therm
author_rank: Frequent Contributor
timestamp: November 28, 2022, 08:38:59 pm
content: Here is a manually selectable 6 way switch:RS Stock No. 219-4618here are special relays for t/c with low coil power:https://www.pickeringrelay.com/applications/thermocouple-switching/

author: magic
author_rank: Super Contributor
timestamp: November 28, 2022, 08:51:21 pm
content: Quote from: Mazo on November 28, 2022, 08:17:27 pmWell, yes, it matters.Type K sensitivity is 41µV/°C, so for 10°C you need 410µV accuracy in the signal chain.0.41mV is not a huge deal.

author: Mazo
author_rank: Regular Contributor
timestamp: November 28, 2022, 10:22:56 pm
content: Quote from: mag_therm on November 28, 2022, 08:38:59 pmThank you for the links,but I am in search of design to go on a PCB and be mass produced,also it should be electronically controlled.While the relays do fit the requirements,they will click all the time while the thermocouples are "scanned" so I stray from that solution(also,I doubt that they will be cheaper than just 8 channel amplifier with no switching).------------------------------------------------------------Quote from: magic on November 28, 2022, 08:51:21 pmI am well aware of the basics and looking for more in-depth experience,if you have some please do share---------------------------------------------------------------Quote from: Kleinstein on November 28, 2022, 08:25:16 pmThanks
Analog synthesizer project - Page 1
Forum section: electronics / projects

author: ResR
author_rank: Regular Contributor
timestamp: December 21, 2013, 07:38:27 pm
content: I made this 3xOsc type analog synthesizer PCB with a 2-way filter and a extra sound effect generator using only transistors. I was planning to add an echo function also, but I have no idea how to make sound echo using transistors. Any suggestions?

author: Hideki
author_rank: Frequent Contributor
timestamp: December 21, 2013, 08:16:02 pm
content: To get an echo you need to delay the audio. You can do that using transistors, but you would need many thousands of them to get enough memory for a decent delay length.I guess the easiest way is to use a PT2399 chip - a delay/echo integrated circuit by Princeton Technologies. There are many dsigned based on it floating around on the net.

author: calexanian
author_rank: Super Contributor
timestamp: December 22, 2013, 02:21:34 am
content: The Princeton chip is good, but the fidelity gets pretty bad when you extend the delay past a half second or so. Have a look at what Metasonix is doing with their euro rack spring reverb. Accutronics now makes a tiny little spring reverb unit. May be worth a look.

author: SeanB
author_rank: Super Contributor
timestamp: December 22, 2013, 06:59:48 am
content: I have a spring delay doing nothing, a little worn. I will dig it out and take a photo or two of it.

author: ResR
author_rank: Regular Contributor
timestamp: December 22, 2013, 05:25:02 pm
content: Thanks for help, I take a look for it now when I know what to look for.

author: old gregg
author_rank: Regular Contributor
timestamp: December 24, 2013, 08:42:45 pm
content: there's also some reissue of the old BBD chips by Cool Audio. Those chips need a clock and more external components but sound is nicer (look at the electro harmonix memory , boss DM2 , both effect pedal).I didn't find the cheap princeton chip really nice (noise, artefact, ect...). Their obsolete PT2395 seemed more interesting but not made anymore (maybe some seller have them in stock though)If you have programming skills, Spin Semiconductor made available a micro-processor dedicated to audio effect, the FV1 which is in a lot of products today.

author: calexanian
author_rank: Super Contributor
timestamp: December 24, 2013, 11:33:45 pm
content: Somebody needs to write up some firmware to just write to some ram, and then read it out. An A/D in, and an D/A out. Programmable count length before repeating. Should be easy. Read out old word from memory location, write in new word. Continue to next address. After so many, go back, start over. Then we can use all of the super cheap fast ram we have out there. As much delay as you want.
Analog tempco compensation for ZnO gas sensor - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: January 09, 2020, 03:46:51 pm
content: I'd like to remove the tempco from an MQ-2 sensor. Circuitry is all analog (op-amps), minimal complexity. Perfection is not needed. Attached are two plotsEPCOS Resistance/temperature characteristicsMQ-2 Rs/RoThe plots have somewhat different axis, but I think show essentially the same thing; how resistance varies with temperature.Looking at the EPCOS NTC B=2000 curve and the MQ2 33% RH curve, and ignoring the small difference in "baseline temperature" (25C at top, 20C at bottom) then it seems below 20C, the curves track well but above the MQ-2 curve is much flatter.What I would like is that the NTC curve is simply some scaled, shifted version of the MQ2 curve, then I could believe it'd easy to implement compensation.
ANALOG TO DIGITAL CONVERTER FOR INDUSTRIAL APPLICATIONS - Page 1
Forum section: electronics / projects

author: cRash1001
author_rank: Contributor
timestamp: January 08, 2017, 06:44:00 am
content: I have been using R1SE-0505/H2-R for isolated power supply for ADC MAX1300. I was told that using the R1SE for power supply will be same as just using a LDO to supply the ADC. So, what would be better to supply power to the ADC a low noise LDO or isolated power through R1SE-0505/H2-R? Inside R1SE-0505/H2-R is a transformer with some components for oscillation.

author: kiran_shrestha
author_rank: Regular Contributor
timestamp: January 08, 2017, 02:36:56 pm
content: No.. you should use small LDO after R1SE because R1SE output is not so good for ADC... I have tried it... by the way are u making isolated current sensing...hahah.. just wondering...

author: cRash1001
author_rank: Contributor
timestamp: January 10, 2017, 02:47:30 am
content: Kiran bro, its me ditish. Its actullly for industrial application, probably for to work in conjuction with PLC or something. So, its better if just use a low noise LDO instead of R1se?

author: kiran_shrestha
author_rank: Regular Contributor
timestamp: January 10, 2017, 06:17:18 am
content: I though so ..as I have bought R1se long before.... R1SE is isolator and u can use LDO after it and run adc in low voltage 2.8 or 3.3 as R1SE has output is 5V for 5v input.
Analog TV tuner datasheet? (probably) ALPS TMDG2-731A - Page 1
Forum section: electronics / projects

author: Yansi
author_rank: Super Contributor
timestamp: July 31, 2019, 12:54:34 pm
content: Hello,today sifting through some trash, I found a tuner from a VCR set, the TMDG2-731A, probably made (or designed) by ALPS.I have quickly found a couple of service manuals including schematics, so I know the basic pinout. However, the tuner requires I2C control. Is there any standard to this or any chance finding the documentation?I have cracked it open to see the IC names, however those bastards from ALPS even re-branded the chips, so I only got some ALP029, ALP018TT and ALP115, even though it seems that each of the chips were a completely different manufacturer (considering the style of the package and font). Not very telling. Rebranding chips shall be a crime!Is the tuner worth keeping (considering a suitable documentation for the control will be found) or shall I put it back into trash with others alike? (... and put the trash where it belongs)Thanks for any hints how to ID the sucker.Y.

author: Yansi
author_rank: Super Contributor
timestamp: July 31, 2019, 03:32:12 pm
content: SO i thought: what about turning with a package type and brief IC description to a google?After a couple mins on google, I have found the main tuner/synth IC may be Texas Instruments SN761672. The pinout (at least GND pins and I2C pins) match. However, having a series resistance of 390ohm in SCL and about 800ohms in SDA looks kind-of weird, the paths still match the pinout from the service manual and pinout of the tuner IC. SDA goes to SDA, SCL goes to SCL, AS goes to AS.Okay, found one finally, see attached datasheet of the IC. So one down, two remaining.
Analog volume control for output of MAX98357A - Page 1
Forum section: electronics / projects

author: Axk
author_rank: Regular Contributor
timestamp: May 30, 2021, 02:42:14 pm
content: Need a log pot for volume control for the output of MAX98357A (small class D amp with I2S input) (3.5W output max)I know about the option of software control (in Linux in my case), but this question is about analog control.I've found some linear 2W 1-300R (the approximate range I need) pots on Aliexpress but all the LOG pots appear to be high resistance or low power, so not suitable for direct attenuation.So I'm looking for some simple solution for the push-pull output of the amp, ideally some attenuator chip that is controlled by a high resistance low power pot.

author: Caliaxy
author_rank: Frequent Contributor
timestamp: May 30, 2021, 03:11:24 pm
content: Quote from: Axk on May 30, 2021, 02:42:14 pm... because they are meant to be connected at the input of the amplifier. Why do you want to put the pot at the output?

author: Axk
author_rank: Regular Contributor
timestamp: May 30, 2021, 04:53:17 pm
content: Yes, I understand.But in my case the amplifier doesn't have analog volume control, supposed to be controlled in software so that the I2S input is at the required level.

author: Caliaxy
author_rank: Frequent Contributor
timestamp: May 30, 2021, 06:34:21 pm
content: I see. Have you considered using the "Gain" control pin? According to the data sheet, you can get five levels of gain (3, 6, 9, 12 and 15 dB) by connecting a 100K resistor (or shorting the gain input) to GND or VDD.It might be next to impossible to find a suitable pot for the output (most power pots are wire-wound and linear, as you noticed). You could experiment with a rotary switch and fixed resistors. But this might be more expensive than controlling the gain directly with a single 100K low power resistor and a rotary switch.

author: Axk
author_rank: Regular Contributor
timestamp: May 30, 2021, 08:09:39 pm
content: Thanks!I know about the gain control pin. Ideally I need the control to be smooth like with an analog amp with a pot.

author: Marco
author_rank: Super Contributor
timestamp: May 30, 2021, 08:42:55 pm
content: Quote from: Axk on May 30, 2021, 02:42:14 pmModulating the output of a class D amplifier with a rheostat is too painful for me think too much about.If you're using Linux surely you can find some way to use the 32 bit mode for doing digital gain? That's 16 bits of modulation with a 16 bit signal, plenty smooth.

author: Axk
author_rank: Regular Contributor
timestamp: May 30, 2021, 09:26:34 pm
content: Yes, that's probably what I'll have to do. Looks like there's no simple analog solution to this.

author: oPossum
author_rank: Super Contributor
timestamp: May 30, 2021, 09:40:25 pm
content: The part you are searching for is typically called an L-Pad. They are used for in-wall speaker level control and tweaking mid/tweeter levels in speaker cabinets.https://www.parts-express.com/speaker-components/crossover-components/speaker-l-pads