hybridfree/eevblog-posts huggingface dataset:
Linear power supply question - Page 1
Forum section: electronics / beginners

author: eamoex
author_rank: Contributor
timestamp: May 17, 2020, 07:48:00 pm
content: I see these power supplies on eBayhttps://www.ebay.com/itm/Ultra-Low-Noise-linear-power-supply-LPS-PSU-KIT-5V-9V-12V-15V-18V-24V-/121940137982but I don't understand how they work. Where is the bridge rectifier, where is the transformer?

author: tunk
author_rank: Super Contributor
timestamp: May 17, 2020, 08:26:44 pm
content: It's a kit, you have to supply the transformer yourself.And I guess the four TO-220s mounted on heatsinks are the rectifier.Some more info which may be this supply:https://www.amb.org/audio/sigma11/

author: tkamiya
author_rank: Super Contributor
timestamp: May 17, 2020, 09:19:15 pm
content: According to schematic, transformer AC in goes into where it shows AC on left bottom of PCB. Bridge rectifiers are on heatsink. Kind of an odd design....

author: John B
author_rank: Frequent Contributor
timestamp: May 18, 2020, 12:03:04 am
content: It then looks like you have to bolt the whole unit to a subsequent heatsink. It looks like the pass transistors stick out the bottom.

author: tkamiya
author_rank: Super Contributor
timestamp: May 18, 2020, 01:20:03 am
content: That's MOSFET, and yes, it is meant to be bolted to the bottom of the case or heat sink.In the page itself, there is a reference to a project that this product is based on. If you go there, you can see the whole thing. There are two MOSFET devices that sticks out and are meant to bolt to the chasis. I've seen hundreds of these offers on eBay, including dis-similar designs but all stating it is for the audio low noise applications.What I got was a PCB and pile of parts. No instruction. The regulator IC was an obvious PULL and recycled parts AND different from the one that's advertised. It was lower rated (current wise) version. It also did not match the PCB. (3 pin device into 5 hole PCB pattern) NO instructions. When I complained, the seller put up a wall but when I pressed on, he quickly refunded the full amount and went away.I advise caution on these.... or at least expect all kinds of issues.

author: John B
author_rank: Frequent Contributor
timestamp: May 18, 2020, 01:24:57 am
content: I would expect fake transistors and also I would be very sceptical of the provenance of those large caps. They would be expensive if genuine and would be an obvious item to be faked as well.

author: tkamiya
author_rank: Super Contributor
timestamp: May 18, 2020, 01:38:08 am
content: The kit I bought had multiple of those large caps by NICHICON. I put it on my capacitor tester. At least capacity was correct and leakage was reasonable. But I have no reason to believe they were actually NICHICON 105C version. I'm starting to develop an aversion to those kits from these regions. Prices are too good to be true.I've actually didn't build mine. Patterns on PCB was wrong for the IC and didn't feel like spending time and working with substandard products.

author: eamoex
author_rank: Contributor
timestamp: May 18, 2020, 07:37:00 pm
content: Thanks everyone. That's enough to steer me away from these.
[SOLVED]Linear powersupply output grounding issue. - Page 1
Forum section: electronics / beginners

author: Valentin
author_rank: Newbie
timestamp: June 02, 2019, 06:26:16 pm
content: Hello wonderful people of the forum! I'm having this issue with my bench power supply, where if I connect one of its leads to ground it sinks a lot of current trough to ground. The power supply is based on an ua723(lm723) and it uses a regular transformer. I had a suspicion that maybe the transformer had bad lacquer and was causing my issue because between ground and the negative output I only had ac voltage difference which I was expecting but for some reason it syncs a bunch of current, and it fries my driving transistor(bd240) but my power transistors(2n3055) are fine, so I replaced it with a torroidal one which I know is good but sadly my problem still persists. What could be the issue?

author: Twoflower
author_rank: Frequent Contributor
timestamp: June 02, 2019, 06:34:46 pm
content: Check if the housing of the 2N3055 is insulated from the chasis. At least that was the problem on my cheap (self build) supply. The mica sheet got defective over time.

author: Valentin
author_rank: Newbie
timestamp: June 02, 2019, 07:36:28 pm
content: QuoteAh yes, it wasn't exactly that, but something very simmilar. When my father put the thing together back in the day he was relying on the metal case's powder coating as an insulator, it got damaged and so the positive side was grounded instead of the negative. I'll go get some insulators tomorrow. Thanks for the help! ^_^
Linear region of a Mosfet - Page 1
Forum section: electronics / beginners

author: swer
author_rank: Newbie
timestamp: July 07, 2010, 05:50:45 pm
content: Hello you all;I would like to use a mosfet as a resistor in it's linear region.What should I do for it?How can I define a mosfet's linear region ? Can I find it on the mosfet's datasheet ?Thanksswer

author: Zero999
author_rank: Super Contributor
timestamp: July 07, 2010, 06:51:51 pm
content: http://en.wikipedia.org/wiki/Mosfet#Modes_of_operation
linear regulator (igbt) schematic - Page 1
Forum section: electronics / beginners

author: MINING123STUDIOS
author_rank: Newbie
timestamp: June 11, 2024, 05:52:04 pm
content: Hi,I want to convert a constant 12V supply intoto a constant 5V supply.would the schematic work?d4 is BZV55B5V1 (https://assets.nexperia.com/documents/data-sheet/BZV55_SER.pdf)the igbt is IXYP60N65A5 (https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/2615/IXYP60N65A5.pdf)

author: BILLPOD
author_rank: Frequent Contributor
timestamp: June 11, 2024, 06:29:15 pm
content: Good Morning MINING123STUDIOS, what is under the blue blob???

author: Gyro
author_rank: Super Contributor
timestamp: June 11, 2024, 06:50:40 pm
content: Hi,Why an IGBT? You haven't indicated what (how much) current you need to regulate, but the IGBT indicated is optimized for high voltage, high current switching (as are most IGBTs) and the datasheet doesn't show any forward biased linear SOA (Safe Operating Area) curve.

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 11, 2024, 07:57:07 pm
content: Quote from: MINING123STUDIOS on June 11, 2024, 05:52:04 pmNo?I mean, that's generallynothow MOSFET work (and IGBT is just MOSFET slapped into BJT). You bias your gate at 5V, and the IGBT will drop its emitter to who knows what voltage depends on VGE(TH). You can do that with BJTs because VBEdrops are generally pretty small, it isn't the case with MOSFETs where VGS(TH)are often large and not well controlled.

author: David Hess
author_rank: Super Contributor
timestamp: June 11, 2024, 09:02:43 pm
content: That will work, however the Vgs(th) (threshold voltage) of a IGBP or MOSFET is poorly controlled, so the zener voltage will likely need to be trimmed for an accurate output voltage. A 2 transistor design solves that as shown below, with Q1 replaced by the IGBP or MOSFET.

author: twospoons
author_rank: Frequent Contributor
timestamp: June 11, 2024, 09:28:19 pm
content: Why reinvent the wheel? A 7805 will do a better job than an igbt + zener.

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 11, 2024, 10:01:03 pm
content: Would it work? Perhaps. If the definition of working is outputting a voltage.Would it regulate to your desired voltage? No.Besides the wide spread of the Vge(on) previously mentioned, there is no feedback.
Linear regulator control circuit feedback - Page 1
Forum section: electronics / beginners

author: obuone
author_rank: Contributor
timestamp: April 12, 2019, 08:08:22 am
content: Hello everybody.I am designing my first power supply for a while now. In the design I am trying to adopt the control circuit form Dave's uSupply but I am using different Linear regulator with 1.22V reference voltage. So to be able to go down to 0V it have to driven negative which complicates things.What are the drawbacks when having a feedback from the output (divided by 10) and directly comparing it with the set from DAC voltage. Is this configuration less stable than just injecting voltage in the set pin from the DAC with times 10 gain instead.Thank you.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 12, 2019, 08:53:14 am
content: Using the extra OP in the feedback path makes stability of the control much more difficult. The extra OP is now part or even the main part of the control loop, the regulator is more or less reduced to a kind of protected transistor with no so well known AC properties and maybe relatively poor speed. So in this case using the regulator is making the control loop more difficult than using a bare transistor instead. The main advantage is that the regulator internal over-temperature protection may be still in effect - if it still works with the reference pin higher than the output.Just adding a voltage to the reference pin is not effecting the regulator control loop very much (only the slight effect of the impedance added). So the control would be still inside the regulator chip.

author: obuone
author_rank: Contributor
timestamp: April 12, 2019, 09:01:48 am
content: I ran few simulations and at certain loads the circuit with the output feedback was oscillating, adding something like 40-50mV ripple at the output. Thought it is just an erroneous effect from the OPamp model, but your explanation makes much more sense, thanks

author: David Hess
author_rank: Super Contributor
timestamp: April 12, 2019, 05:19:08 pm
content: Taking feedback from the output eliminates all errors contributed by the regulator. If you are designing for low noise or low drift, then this is the way to do it.However like Kleinstein says, taking feedback from the output places the regulator within the control loop complicating frequency compensation. Personally I have never had problems doing this but the frequency compensation should be verified empirically which only requires a pulse or function generator and oscilloscope. If you do the frequency compensation this way, then it is possible to work back and derive the AC characteristics of the integrated regulator.
Linear Regulator in series for symmetrical PS?  - Page 1
Forum section: electronics / beginners

author: dougduck
author_rank: Newbie
timestamp: June 29, 2024, 02:56:00 am
content: What are the problems with using a linear regulator like the LM317 in series to have a symmetrical PS? (isolated windings)The most common is to use the negative regulator, but i want to manufacture some boards, and this makes it easier to make a single positive design and be able to use it in series if i need a symmetrical source.Can anyone explain to me if there would be any problem with load balancing or any other problem?

author: Andy Chee
author_rank: Super Contributor
timestamp: June 29, 2024, 04:54:52 am
content: The problem with isolated windings is that the device being powered may not like it.Is this supposed to be a generic laboratory supply? Or do you have a specific device being powered?

author: Kleinstein
author_rank: Super Contributor
timestamp: June 29, 2024, 08:27:29 am
content: It is OK to have 2 fully seprate positive regulators (including isolated transformer windings) and than series connect the 2 regulated voltages. This is how most dual lab supplies are build.It however really need them to be seprate and one can not use something like a split transformer winding.What is problematic is having the 2 regualtors from the same raw DC in series. In this can one would have to make sure that the load current is higher at the lower part (which looks like the negative side to the outside).The normal way is to use a LM317 and LM337 for the negative side or corresponding fixed voltage ones.
[SOLVED] Linear regulators still work if input voltage is too low, correct? - Page 1
Forum section: electronics / beginners

author: cdevidal
author_rank: Regular Contributor
timestamp: April 25, 2022, 12:02:21 am
content: Sanity check: If I havea 3.3V LDO such as this onewith a 300mV voltage drop and the input voltage drops to 3.4V, the output would be Vin - Vdrop = 3.1V. Correct? I don't see anything about a low-voltage lockout on this LDO.

author: golden_labels
author_rank: Super Contributor
timestamp: April 25, 2022, 12:12:06 am
content: Below the minimum supply voltage the op-amp, the voltage reference and the CE input buffers are not guaranteed to operate. So what voltage you obtain becomes unpredictable. Likely it will be below your calculated 3.04V (note:not really, see bdunham7’s comment below!), but how much below one can’t predict. It may as well turn off completely, if the CE buffers output low. Or if thermal protection pulls the gate too low.

author: cdevidal
author_rank: Regular Contributor
timestamp: April 25, 2022, 12:21:16 am
content: Got it--don't count on it.Now that I think about it, I probably don't even need to worry about this. The project is mating a 3xNiMH battery pack to an ESP32, with a lowest acceptable voltage of 3.0V, typical current of 100-200mA. Discharge curve on NiMH gives 90+% battery life at 200mAH when the cells drop to 1.2V so a regulator with a 360mV drop would do just fine.

author: bdunham7
author_rank: Super Contributor
timestamp: April 25, 2022, 12:59:05 am
content: Quote from: cdevidal on April 25, 2022, 12:02:21 amTypical behavior for LDOs is that if VINstarts going below VOUTplus the dropout voltage, the output starts to droop and becomes approximately VINminus the dropout until some point where it gives up altogether and what happens then varies. In this case, the regulator has an ENABLE pin that requires 1 volt to turn the regulator on, so presumably it would turn off at that point if it is still going. This series goes down to 1.0V, so it is possible it would continue to conduct reasonably well down to that point, although your load device would probably have quit long ago. Of course you'd want to actually test its operation if any of this was critical.Edit--looking further, it appears that the dropout voltage would start to rise when the input goes below 2.0V or so.Keep in mind that the 320mV VDOis the datasheet limit for maximum current of 600mA. Typical dropout voltage is much, much less at lower currents. Unless you are maxing this thing out current-wise, it will probably be nearly as good as you can get without a buck-boost arrangement.
Linear slew rate limiter - Page 1
Forum section: electronics / beginners

author: tsmith35
author_rank: Frequent Contributor
timestamp: October 27, 2013, 10:58:17 pm
content: I got a nice little hot air board heater (Tenma 21-10135) to preheat the bottom of my small circuit boards. It does a nice job, but it heats up very fast. Rather than do a manual ramp by turning the knob, waiting, turning again, waiting and so on, I did some searching and came up with a circuit from edaboard that should provide a nice, linear ramp rate. I know the min and max temps that the temperature control knob will allow, but I'd like to set the ramp up to about 2°C/sec.The only problem is, I'm green when it comes to designing circuits. The poster provided an image of the planned circuit, but I don't know which parts to use or how to calculate the resistor and cap values to provide what I need. Can anyone help, or just point me in the right direction? Thanks.

author: Chrisalat
author_rank: Newbie
timestamp: October 28, 2013, 07:51:43 pm
content: What about using LTsice to simulate it?http://www.linear.com/designtools/software/

author: tsmith35
author_rank: Frequent Contributor
timestamp: October 28, 2013, 08:14:36 pm
content: Quote from: Chrisalat on October 28, 2013, 07:51:43 pmThanks! I kept hoping I'd learn a bit about op-amps and circuit design, but maybe I can hack together some workable values with LTspice.
Linear Technologies 0-24v 0-3A power supply design questions.  - Page 1
Forum section: electronics / beginners

author: FotatoPotato
author_rank: Regular Contributor
timestamp: October 11, 2018, 02:44:59 am
content: Hey all,I've been searching all over the internet for different power supply designs and I found one that I really like. Its a relatively simple and quite efficient design but there is just one part I don't get about it. In the top left of my re-creation of the original schematic there is a block that contains a LTC3632 DC-DC synchronous buck converter. I put it there because it was in the original schematic but I don't know why its there and I would love to understand why its there and what purpose it serves to the power supply.I have linked both the original schematic from Linear Technologies and the Manual that goes along with it and also my re-creation of the schematic.Manual:http://www.analog.com/media/en/dsp-documentation/evaluation-kit-manuals/DC2132AF.PDFOriginal schematic:http://www.analog.com/media/en/technical-documentation/eval-board-schematic/DC2132A-1-SCH.PDFMy schematic:https://www.mediafire.com/file/7bvujejet7e4ppu/Altium_Re-Make.pdf/fileThanks

author: BravoV
author_rank: Super Contributor
timestamp: October 11, 2018, 03:15:31 am
content: Just fyi, there was a review by forum member here ->Linear Technology DC2132A CV&CC Adj. Bench Power Supply BoardAlso BOM cost about sub $50 according to Linear/Analog staff that posted in that thread too.

author: FotatoPotato
author_rank: Regular Contributor
timestamp: October 11, 2018, 03:24:28 am
content: Ohhhhhhhh.....I see now, Its for 0v operation. Thanks so much for linking that thread, I'll definitely read over it.Thanks
Linear Technology LT3042 , LDO chip with 79 dB PSRR at 1 Mhz ... - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: July 15, 2015, 04:15:42 am
content: Recently I spotted this chip, and found that it's performance on low noise output is quite impressive, cmiiw. Not sure if there are similar products from others competing manufacturers.Its the Linear Technology LT3042, linky ->LT3042 pageorPDF DatasheetFew interesting charts from the product's journal ...This made me think to use it say like powering sensitive analog front end (eg: buffering circuit and etc) as in measurement circuit/project which sometimes need to be fully "isolated" from the back end circuit, and a quite and clean power source.As isolated power means only few options (cmiiw), either using it's own separated power source which is cumbersome, or using the same power from the back end circuit which far more convenient and less complexity, but through switching power (eg: thru transformer) as in isolation requirement and of course it needs to be "cleaned".Regarding the "cleaning" part, is this chip suitable, or at least a good candidate to be used as a post regulator to power the front end sensitive analog circuit ?Or any other comments or discussion regarding it's performance are welcomed..... and NO, I'm not affiliated with Linear Technology or what so ever ...
Linear Technology sot-23  diode ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: March 29, 2020, 12:42:09 am
content: I'm looking for a dual diode's like this in LTSpice, and I can't find the same of 1 to look and see if it's in LTS. It looks nicer on the schem. to have a real part than 2 diodes.https://www.mouser.com/datasheet/2/395/BAW56%20series%20F10-248565.pdf

author: mikerj
author_rank: Super Contributor
timestamp: March 29, 2020, 09:28:58 am
content: LTSpice is primarily a simulator rather than a schematic editor so this would be very unlikely to exist as there is little need for it. However it would be easy to create your own symbol that uses your favored diode models, could be a nice simple introduction to creating your own parts.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 29, 2020, 09:52:15 am
content: Dual diodes are made for convenience (less parts) and to get good matching / same temperature.In the simulation same model diodes are perfectly matched - sometimes even too good for some circuits to start easy. So there is no need for separate dual diodes. One can just use 2 single diodes in the simulation. In this case it should be relatively close to an 1N4148.The simple models don't include case parasitic effects - so no need to include the case at this level.
linearity of an electronic system - Page 1
Forum section: electronics / beginners

author: harrysmith
author_rank: Contributor
timestamp: October 07, 2020, 09:22:10 pm
content: Hello everyone.how to know in electronics that a system is linear or non-linear. for example how to know if a sensor whatever is linear or non-linear ?

author: TimFox
author_rank: Super Contributor
timestamp: October 07, 2020, 09:37:43 pm
content: All analog systems are non-linear: the correct question is how to quantify the non-linearity. Non-linearity will depend on signal level. Possible answers, depending on what type of system and available equipment:1. For an amplifier, if you have two variable attenuators of known accuracy. Connect generator through first attenuator to amplifier input, and connect appropriate meter through second attenuator to output. Start with second attenuator at reasonably high attenuation and adjust generator and input attenuator to achieve “reasonable” level at meter. Proceed to increase input attenuator (decreasing amplifier input), noting output attenuation required to obtain same meter reading. This old-fashioned method does not rely on wide dynamic range accuracy of generator level or meter accuracy.2. Use an distortion meter (or spectrum analyzer) to measure distortion products as a function of signal level. Either harmonic distortion or two-tone modulation products.Linearity is not exactly synonymous with proportionality, when there is a constant offset with zero input for DC systems.What kind of systems are of interest to you?

author: David Hess
author_rank: Super Contributor
timestamp: October 08, 2020, 01:25:26 am
content: In either case, a known linear excitation is applied to the transducer or electronic system and the result is measured. For systems which can process AC, excitation can be a sine wave and distortion or distribution measured, a triangle wave or ramp and distribution measured, or DC levels.

author: harrysmith
author_rank: Contributor
timestamp: October 08, 2020, 01:56:55 am
content: precisely on a datasheet of a BPW41N photodiode sensor. or I can know its linearity. do we observe these graph characteristic of the datasheet. if so how ?https://pdf1.alldatasheet.com/datasheet-pdf/view/26252/VISHAY/BPW41N.html

author: Cerebus
author_rank: Super Contributor
timestamp: October 08, 2020, 01:57:25 am
content: Much more fundamentally, if you apply signal A to a system and record the response Aout, then do the same with signal B, result Bout, then apply the sum A+B as input and the output (A+B)outis the same as the sum of the previously recorded outputs Aout+ Boutthen the system is linear, by definition.

author: harrysmith
author_rank: Contributor
timestamp: October 08, 2020, 02:43:17 am
content: can we confirm the linearity from the graph of the BPW41N datasheet if yes which graph is conserne ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 08, 2020, 04:47:22 am
content: Fig.3 shows a linear response.Just how many posts are you going to write on this subject? Have you read the definition of "linearity"? Do you know how to prove a system is linear?Tim
Link between reluctance and inductance - Page 1
Forum section: electronics / beginners

author: rs20
author_rank: Super Contributor
timestamp: January 16, 2015, 07:59:45 am
content: I'll start off with my question:-- Is my understanding of inductors wrong, or-- Is my $20 eBay component identifier failing me as an L meter?Here's what I did: I wrapped a (presumably steel) nail with Kapton tape, and then wrapped a whole bunch (est. 250) of windings of enamelled copper wire around it. De-enammeled the ends with a flame, plugged it into my cheap meter, and it reads 0.7 ohms + 0.09mH. So, then I add a steel screwdriver touching both ends of the nail (yes, the nail was bent to enable this). I was expecting the screwdriver to "complete the magnetic circuit", increasing the permeance* and thus increasing the inductance. Yet, I take another reading with the meter, and it reads 0.7 ohms + 0.09mH... exactly the same as before. Am I down in the noise floor of the component identifier, or am I wrong to expect a change in inductance? I feel like gapped transformers have a lower mutual inductance because the gap sorta ""breaks"" the magnetic circuit, and was expecting a similar effect here.* (I am in no way qualified to use this term with such confidence)

author: johansen
author_rank: Super Contributor
timestamp: January 16, 2015, 09:55:04 am
content: no, you're down below the noise floor of eddy current and hysteresis eating up the energy.try the same experiment again using a ferrite core and you'll find yourself back in reasonable territory.

author: Circlotron
author_rank: Super Contributor
timestamp: January 19, 2015, 11:03:46 am
content: The circumference of the nail is probably acting as a shorted turn secondary winding. That's why transformers have strips of laminations with an insulating coating on each.
Linking/repeating IR remote signal - Page 1
Forum section: electronics / beginners

author: gbuilder
author_rank: Newbie
timestamp: April 07, 2018, 07:05:18 pm
content: I’m working on adding IR remote control to my DIY audio devices (initially DAC and preamp, but possibly others in future). Since they are out of sight I would like them to be controlled by a single IR receiver module on the end of a cable.All of my devices have an MCU which I can use to decode the IR signal and control the device accordingly, by switching relays etc.My first attempt on a single device looks like this. Simple, but working fine. Only the IR part of the device is shown here.https://ibb.co/kdKhexThe problems are:1) I need separate IR receivers for each device. Messy.2) In cases where different devices are set to respond to the same signal from the remote, (e.g. standby button), there is a risk that some might receive the signal and others not. So for example the DAC might switch off but the preamp stays on.It would be better if the devices all respond to the same IR receiver. Unfortunately, this is where my understanding of interfacing signals lets me down...Since the devices are all operating off separate power supplies I don’t think I can simply connect the IR receiver output to the different devices in parallel. Is that correct? I thought about isolating the output signal for the second device using an optocoupler, but this doesn’t seem to be working on my test circuit, shown here:https://ibb.co/bHXPsHI’d be interested to learn where I am going wrong here. I’d also love to know if anyone has already got a solution I can study.I’m aware that some brands have got proprietary link systems, and there are also standardised protocols, e.g. 12V trigger. The thing I like about my approach is that you don’t need to know anything about the other connected devices. They just receive the IR signal as if they were connected to the IR receiver directly.

author: nrxnrx
author_rank: Unknown
timestamp: April 08, 2018, 10:37:06 am
content: Amateur here, so be warned...In the case of the TSOP382xx receivers, for example, the output has a transistor pulling 30kohms from VCC to GND. The output may not be able to drive your opto directly.

author: gbuilder
author_rank: Newbie
timestamp: April 08, 2018, 01:24:24 pm
content: A veritable expert compared to me, I'm sure!I'm using a similar receiver TSOP2238 with the output arrangement you described. Optocoupler is HCPL-817.I think you could be right. If VCC is 5V and R 33kOhms then the output current is 5/33k=0.15mA, right? Fine to connect to a GPIO but perhaps not sufficient to drive the opto. I can't actually work out current requirement from the datasheet. But I will try and use a transistor to drive the opto, with the IR signal feeding the transistor base.Thanks for taking the time to look at my circuit.
links to cheap adjustable voltage triggers > switches - Page 1
Forum section: electronics / beginners

author: user1235423643
author_rank: Regular Contributor
timestamp: July 07, 2016, 12:01:04 pm
content: hello, can anyone recommend any cheap little circuits that can be setup to trigger at set voltages.for example. when i sees X voltage it will trigger a relay or transistor. and the unit can be adjusted with a pot. to X voltage.even better is there is such a unit that does high and low settings. max and min.(VSR voltage sensitive relays are on the market but cost over $50) retail stuff to $thanks

author: MosherIV
author_rank: Super Contributor
timestamp: July 07, 2016, 12:07:20 pm
content: I think this should work for youhttp://www.zen22142.zen.co.uk/Circuits/Switching/schmitt.htm

author: Seekonk
author_rank: Super Contributor
timestamp: July 07, 2016, 02:06:16 pm
content: The three terminal LM431 easily drives small relays. Check application notes.

author: Signal32
author_rank: Frequent Contributor
timestamp: July 07, 2016, 04:46:14 pm
content: Perhapshttp://www.ebay.com/itm/-/222087837604"enter a Voltage comparison with setting reference voltage, when the input voltage is greater than the reference voltage, the relay closed; when the input voltage is less than the reference voltage, the relay no action."Doesn't sound like it would have min/max function, but you can use 2 to get min/max functionality.Or this:http://www.ebay.com/itm/-/162039421625This one seems to be able to do min/max with only one unitDid you want schematics or ready-made circuits?

author: user1235423643
author_rank: Regular Contributor
timestamp: July 10, 2016, 02:44:07 pm
content: yes something ready made prebuildso it would be a Voltage Comparator ?

author: mariush
author_rank: Super Contributor
timestamp: July 10, 2016, 03:17:26 pm
content: Lots of chips like what you want.There's several sections at Digikey that have chips like what you want.PMIC - Power Supply Controllers, Monitors see , Specialized ( filter by Applications) :http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-power-supply-controllers-monitors/2556707PMIC - Supervisors :http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-supervisors/2556197PMIC Battery Management (see battery monitor or battery protection there ) :http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-battery-management/2556336PMIC - Power Management - Specialized :http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-power-management-specialized/2556708filter by overvoltage protectionSpecialized ICs (see overvoltage protection at type) :http://www.digikey.com/product-search/en/integrated-circuits-ics/specialized-ics/2556114

author: user1235423643
author_rank: Regular Contributor
timestamp: July 11, 2016, 04:12:03 pm
content: thanks. but digi key is no help.any ebay links?
Linux electronics circuit simulators - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: April 27, 2014, 01:18:21 am
content: even with the risk that somebody will hate me for the tens of posts I am starting, but this is my speed, please give me a cold showerHad a look at Oregano, but documentation is poor. Got lost on forums.Let's take a simple example: I have this LM393 and I want to implement a delay timer with it. Is it possible to simulate at least such a trivial circuit with any of this software?

author: TerminalJack505
author_rank: Super Contributor
timestamp: April 27, 2014, 01:59:45 am
content: The only Linux simulator that I have used is Qucs. It had a lot of potential but it seems like the developers abandoned the project.It's usable so you might give it a shot. A lot of the circuits I tried to simulate wouldn't. At least not without having to jack around with a bunch of parameters.

author: c4757p
author_rank: Super Contributor
timestamp: April 27, 2014, 02:07:09 am
content: Screw all the native Linux sims, run SPICE in WINE. Works a treatEdit - er... LTspice. Not just any SPICE.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 27, 2014, 05:09:38 am
content: Quote from: TerminalJack505 on April 27, 2014, 01:59:45 amSounds like normal SPICE to meGuessing Qucs is based on... 3f5, or XSpice? Which is the same basis for most any other flavor you'll cross today, give or take their own proprietary mods/extensions.Tim

author: bingo600
author_rank: Super Contributor
timestamp: April 27, 2014, 02:19:13 pm
content: I use lts-pice in Wine on a linux mint 14 , works excellent/Bingo

author: Franz Zinn
author_rank: Contributor
timestamp: April 27, 2014, 04:19:45 pm
content: If you are comfortable with the spice syntax try ngspicehttp://ngspice.sourceforge.net/

author: mrflibble
author_rank: Super Contributor
timestamp: April 27, 2014, 04:33:49 pm
content: ltspice running in wine.Nuf said.

author: richard.cs
author_rank: Super Contributor
timestamp: April 28, 2014, 08:36:49 am
content: Quote from: mrflibble on April 27, 2014, 04:33:49 pmAnother vote for this.

author: Dago
author_rank: Frequent Contributor
timestamp: April 28, 2014, 10:28:12 am
content: Quote from: mrflibble on April 27, 2014, 04:33:49 pmThis works great for me as well!
linux on arm (imx233) need supporting chip to get any real work done - Page 1
Forum section: electronics / beginners

author: pmurdock
author_rank: Contributor
timestamp: October 12, 2013, 03:26:47 pm
content: I've been toying around with embedded Linux on a freescale imx233. However I would like a bunch of sensors and such and I am not seeing alot of peripherals on these applications processors.Is it normal to have to add a cortex-m3 or atmel xmega micro to get any real work done in addition to the imx233?Granted the imx233 gives me alot of communications capabilities by the nature of Linux.. Do people just use the SPI bus to communicate with a micro to gather the data?Cheers!Paul

author: AndyC_772
author_rank: Super Contributor
timestamp: October 12, 2013, 04:18:56 pm
content: Depends what you mean by 'real work', but if you need access to peripherals and interfaces that aren't built in to the processor you're using, then a separate one to add those capabilities wouldn't be a bad idea. Another option is to see if there's a related part that does include the interfaces you need.Many, if not most, processors are developed to suit a particular target market, and incorporate a set of peripherals which are a good fit for that market. If you need anything a bit out of the ordinary, then it's pretty normal to end up with a design that's less simple and elegant than you might have hoped.If this job were easy, any fool could do it - and I'd be out of work!

author: pmurdock
author_rank: Contributor
timestamp: October 12, 2013, 11:53:03 pm
content: Thanks.. indeed I beginning to understand the complexities. It appears that in general to get a good linux capable processor one sacrifices a lot of peripherals that one would normally find on a microcontroller.Cheers!
Linux/Windows compatible USB or RS232 I2C tool  - Page 1
Forum section: electronics / beginners

author: jpyeron
author_rank: Regular Contributor
timestamp: July 24, 2021, 12:07:10 am
content: Looking for a device that can act as a master or slave for I2C and does not require proprietary software.Bought ViewTool Ginkgo USB to I2C Adapter Support Windows/Linux/Mac/Android/Raspberry Pi, USB-I2C IIC Compatible with CAN/SPI/UART/ADC/DAC/GPIOhttps://www.amazon.com/gp/product/B00ZW45VYY, but read the vendor page and it does not look very opensource friendly. They only provide binaries and binary libraries.Suggestions? Looking in the similar price point +/- 100% . Supporting other capabilities are nice too.I seehttps://www.digikey.com/en/products/detail/ftdi-future-technology-devices-international-ltd/C232HM-DDHSL-0/2714139andhttps://www.digikey.com/en/products/detail/ftdi-future-technology-devices-international-ltd/UMFT200XD-WE/6173760

author: rstofer
author_rank: Super Contributor
timestamp: July 24, 2021, 02:30:56 am
content: If you want to write all of the application code, an Arduino can work as an I2C Master or Slavehttps://www.arduino.cc/en/Tutorial/LibraryExamples/MasterReaderAny of the ARM chips can do it better and may have more I2c peripherals. The Teensy 4.1 has 3 such peripherals and runs at 600 MHz. There is an 'Arduino like' library so the code should nearly port between the Teensy and the Arduino.

author: djacobow
author_rank: Super Contributor
timestamp: July 24, 2021, 02:41:31 am
content: If you want something cooked, look at a Bus Pirate or an FTDI 2232 breakout board.Bus Pirate takes commands directly to do i2c stuff and FTDI has nice library support. Check out PyFTDI.

author: richmit
author_rank: Contributor
timestamp: July 25, 2021, 11:59:16 pm
content: In addition to the bus pirate, I also have these:I2C driver is nice. It only knows about I2C, so it is a much more limited device than the bus pirate or the Binho Nova. But sometimes a dedicated tool is more useful. It has good python support. It comes with a GUI (python) and command line tool. The tiny little display is actually useful.https://i2cdriver.com/The Binho Nova is more like the bus pirate in that it understands lots of protocols. It has a nice GUI and very good python API. Unlike the bus pirate, this one is not very comfortable to use directly via a serial terminal -- for interactive use I think they expect people to use the GUI. For the most part I only use this one via the API, and it is really good for that use case.https://binho.io/Lastly I have the Digital Discovery. This is more of a digital swiss army knife. I mostly use it as a logic analyzer, but it has very good support for I2C. Programming is done via JavaScript inside a proprietary application.https://reference.digilentinc.com/test-and-measurement/digital-discovery/start-mitch
lion battery charging - Page 1
Forum section: electronics / beginners

author: quadzillatech
author_rank: Contributor
timestamp: April 15, 2019, 12:43:42 pm
content: hi all i have a homebrew laser,its got 6x lion batterys in paralell total 14ah, powering a driver board,im currently using a charger for a single cell that outputs 600ma tops,it takes forever to charge,is there any way i can use my bench psu to charge them say upto 75% then top them off with the single cell charger,my bench psu is 0-30v max 30 amp,just wondered what the max amp ball park figure would be ok,cheers Paul m3vuv.

author: capt bullshot
author_rank: Super Contributor
timestamp: April 15, 2019, 12:51:19 pm
content: Typically, one can charge each cell at 1C to 4.2V end-of-charge voltage.So if you charge all your cells in parallel, set your supply to 4.2V / 14A and wait until the current starts to decay. At this point the cells should be largely charged. Stop at e.g. 20% of your initial current.Don't set your house on fire.Edit: Use a DMM or similar having an accuracy of better than 1% to measure the voltage. Most lab supplies don't read the voltage accurate enough.

author: Cliff Matthews
author_rank: Unknown
timestamp: April 15, 2019, 12:57:25 pm
content: Does your bench supply have current limiting? Stay safe.. each cell has a maximum charge rate.Lots of info available here.

author: quadzillatech
author_rank: Contributor
timestamp: April 15, 2019, 01:09:22 pm
content: Hi thanks for the replies,my psu has current liimiting,in so much if it goes above a preset limit the out put cuts off,not ideal,i normaly set the voltage using my fluke 85,regards m3-vuv.
Lion cell charging - Page 1
Forum section: electronics / beginners

author: Matthew98
author_rank: Regular Contributor
timestamp: April 19, 2017, 12:11:50 pm
content: Hi. Is it ok for a lion cell to raise up to 4.23 V ? This is the reading of my V meter (quite cheap) while charging with repaired Imax charger. It does its thing raising the voltage from 4.2 to 4.23 V and again and again for the cell to hold the charge better, but is it ok in this range ? I thought it was suppose to be 4.18 to 4.2 or something...Thanks !

author: MrAl
author_rank: Super Contributor
timestamp: April 19, 2017, 01:24:00 pm
content: Hello there,In a perfect world the voltage can go up to 4.250v but we dont live there we live here.What this means is that since we dont have a perfect volt meter, we have to be a little careful, and that means we should go under 4.200v just slightly.For example, if your meter reads just 1 percent low, then 4.242 willl read as 4.200 and 4.290 will read as 4.247 so it will look high but possibly ok when it is really over the limit of 4.250 and over the recommended 4.200v.A secondary issue that comes up is that longevity of the cell. The higher in voltage, the lower the life span.I keep mine charging up to 4.150v and i use a special highly accurate voltage reference to make sure my meter is reading properly. The benefit is longer cell life and the drawback is a little less charge held in the cell.It is important to use a good meter for this kind of measurement. For example if the meter is 5 percent low it might read 4.200v when it is really 4.410v which is much too high.

author: Matthew98
author_rank: Regular Contributor
timestamp: April 19, 2017, 02:00:29 pm
content: The meter showed 4.25 at the end of the charging cycle, but when the charging cycle was done, it was spot on 4.2V.I use this charger for charging it fully and than measuring its capacity by discharging, so the cells are charged by this charger only few times ...What im worried about is going it all "bang"))I might buy a voltage source for checking the meter accuracy, though. I saw few precise ones on ebay and I belive Julian Ilett reviewed them.
Lion charger high current - Page 1
Forum section: electronics / beginners

author: unblockgames
author_rank: Newbie
timestamp: March 31, 2017, 03:58:28 pm
content: @eevblog I am attempting to make a very large lion battery backpack somewhere between 60 to 120 ah. I don't want it to take a week to charge, haha. So I'd like to design my own charger circuit. I have watches your videos on lion charging but they don't go into the details of the charging module and I would like to redesign the inner workings of a charging modules so as to handle my very high current needs. I understand the genre concepts of op amp current limiting but I need a bit of .... reinforcement if you will. Please help.

author: senso
author_rank: Frequent Contributor
timestamp: March 31, 2017, 04:06:24 pm
content: All the cell will be in parallel?If not, you will need cell balancing..And some/lots of temperature sensors if you pack the cells together.

author: unblockgames
author_rank: Newbie
timestamp: March 31, 2017, 04:17:48 pm
content: 10 cells parallel per pack, 3 packs in series for 12v for discharge, circuit will put packs back in parallel for charging (essentially balancing every charge cycle)

author: chota.sanjiv
author_rank: Contributor
timestamp: April 02, 2017, 07:58:11 pm
content: First of all you will need to add some balancing circuit so that the cells connected in series can be protected from overcharge and over discharge. Depending on your application you can used active balancing (using energy from fully charged cell to charger others) or passive (dissipate the extra charge as heat) you can check solution from TI and LT for these. For charging unfortunately there is no ready made chip that can do that job, at max the li-ion charger chips can give a 10A current but not more, you will have to use off the shelf li-ion chargers or design a new one yourself. The below link may helphttp://liionbms.com/

author: james_s
author_rank: Super Contributor
timestamp: April 02, 2017, 08:07:29 pm
content: I recommend against designing your own charger. There are good high power off the shelf balancing chargers available for RC aircraft and other toys. Look at Revolectrix productshttp://www.revolectrix.com/cat.chargers.htmThey are highly regarded chargers. Most guys use a pair of converted hot swap server power supplies in series to power them. The LiPo packs typically don't have any sort of internal protection or balancing, they have a balance tap that the charger uses to monitor the cells.
Lipo Balance Charger/Protection Question - Page 1
Forum section: electronics / beginners

author: braden_sun
author_rank: Newbie
timestamp: September 28, 2020, 03:55:26 am
content: Hi all,I am trying to fully understand the following BMS circuit that includes balance charging and protection:https://github.com/ZOUDIO/BMS345. The protection IC is the TI BQ77915 and the charger IC is the TI BQ24650. I have a couple questions about how these circuits work and fit together.1. From the BQ77915 data sheet it states "An OV fault detection occurs when at least one of the cell voltages is measured above the OV threshold, VOV for a time of OV delay, tOVn_DELAY. The CHG FET is turned off." and "The state comparator is turned on when CHG is turned off. If a discharge current is detected, the device immediately switches the CHG back on." I thought current flowed from the drain to the source on a mosfet so if the CHG fet is turned on when a discharge current is detected, wouldn't current be flowing in the direction to charge the battery? I would have thought that the CHG fet is on during UV and DSG fet is on during OV? (See figure 3)2. For the BMS circuit where the charger IC, protection IC and load are connected together on the Pack+ and Pack- terminals, when the charger IC kicks on to charge the battery, the load would be powered off the charger IC and not the battery correct? So you need to account for the current consumed by the load when choosing the charge current? (See figure 1 and 2)Thanks for the help!
LiPo balance port for dual supply opamps - Page 1
Forum section: electronics / beginners

author: paulca
author_rank: Super Contributor
timestamp: December 02, 2017, 06:09:56 pm
content: The voltage across LiPo balance pins caught my attention.Using a 3 series Lipo the voltages are:0-1: 3.7V0-2: 7.4V0-3: 11.1VInteresting ....And....1-0: -3.7V1-2: +3.7VAnd...2-0: -7.4V1-3: +7.4VThose look handy.Looking towards that target of +-12V ... you could series the balance ports, maybe. Then I realised if you are going to use two batteries you might as well use two lipos for the full +12.6V and -12.6V. Then again series across different trios of cells across the packs might help differentiate out the charge voltage differences between the batteries.
LiPo battery charging problem - Page 1
Forum section: electronics / beginners

author: hap2001
author_rank: Regular Contributor
timestamp: April 28, 2024, 01:34:07 pm
content: Hello.My laptop only charges to 98% and not higher, but the voltage tops at about 13.18v, which means almost 4.4v for single cell.Is this something I should worry?Thanks.

author: Gyro
author_rank: Super Contributor
timestamp: April 28, 2024, 01:45:34 pm
content: No. In fact you should use the manufacturer's utility of some other s/w to terminate the charge at around 80%. Your battery will lastfarlonger then.

author: nate_syd
author_rank: Contributor
timestamp: April 28, 2024, 09:21:12 pm
content: If you want to know more about battery longevity - youtube some Jeff Dahn videos, he goes into depth on why you only 80% charge etc.

author: amyk
author_rank: Super Contributor
timestamp: April 28, 2024, 09:53:26 pm
content: I assume this is a 3s pack? Yes, there are lion cells which are rated at 4.4v full:https://electronics.stackexchange.com/questions/519625/4-4v-li-ion-polymer-batteryThe disadvantage of charging them to less than 4.4v is lower capacity, but the advantage is they'll last longer.

author: hap2001
author_rank: Regular Contributor
timestamp: April 29, 2024, 02:35:15 pm
content: Thank you everyone!