hybridfree/eevblog-posts huggingface dataset:
switching IC identification? - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: August 13, 2018, 02:33:21 am
content: The manufacturer of this product has abraded off the number of this SMD-8 switching device.It's in a 2-LED flashlight, one flood and one spot. Pressing the latching pushbutton once turns on the flood LED. Pressing the pushbutton again turns it off. If it is pressed again within a few seconds the spot LED illuminates; if the pushbutton is not pressed within that time period, pressing it again turns on the flood LED again.Based on the delay between successive "ON" presses of the pushbutton, the device enables one of two outputs, turning on one or the other LED.The only cap is in parallel with a resistor creating this time constant.Anyone know what part number this switch device might be?Schematic of the circuit follows. (Transistors--A13sHB--are draw intentionally vague; don't know if they're BJTs or FETs. Anybody know?) Power is a single 18650 cell.Thanks.

author: amyk
author_rank: Super Contributor
timestamp: August 13, 2018, 02:47:54 am
content: Your schematic is messy enough that it doesn't make much sense.A1sHB (not A13sHB) are SI2301DS MOSFETs.There are so many of these that your best bet is to Google "LED手电 IC" and just go through the results one-by-one for something matching.

author: iXod
author_rank: Frequent Contributor
timestamp: August 13, 2018, 03:40:35 pm
content: Schematic is readable for anyone interested.This IC has nothing to do with LED driving. LED current is set by transistors and series resistors.This IC performs solely a switching function.Thanks for your input.

author: Benta
author_rank: Super Contributor
timestamp: August 13, 2018, 04:04:31 pm
content: Probably a small 8-pin MCU. They're so cheap nowadays that making a custom IC doesn't make sense.

author: iXod
author_rank: Frequent Contributor
timestamp: August 13, 2018, 04:29:24 pm
content: Thanks for your reply.If it's a cheap MCU, why erase the ID from the chip? I mean, if it's programmed it wouldn't matter if I did know the IC number, I wouldn't have the code.And if custom IC, replacement not available so no reason to hide ID.This why I still suspect a common (not custom) part number.Thanks.

author: amyk
author_rank: Super Contributor
timestamp: August 15, 2018, 01:59:19 am
content: Quote from: iXod on August 13, 2018, 03:40:35 pmThere are special ICs that do just this switching function, and they are designed for use in LED flashlights. I believe I've seen one mentioned before in a bigclivedotcom video. It's not a microcontroller but an ASIC, because at the volumes these are made, a tiny amount of custom logic is cheaper. They have linear current regulators but in this case the manufacturer added the transistors to drive higher current LEDs.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 15, 2018, 02:03:38 am
content: It's most likely a pic of some unknown provenance, judging by the placement of the power rails.Sent from my ONEPLUS A3000 using Tapatalk
Switching multiple input rails into CN3063 LiPoly charger - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: December 20, 2015, 02:26:33 pm
content: Am I imagining things, or should that high-side-switching P-channel FET be reversed, with its source connected to the input power rail?As per the attachment image (which is taken from the datasheet.)http://www.consonance-elec.com/pdf/datasheet/DSE-CN3063.pdf

author: Paul Price
author_rank: Super Contributor
timestamp: December 20, 2015, 03:12:29 pm
content: There is no need for a P-Chan MOSFET at all, a diode, same as D1 is all that is required. Use of a P-Chan here is wasteful, nonsense.
Switching power rails - Page 1
Forum section: electronics / projects

author: Cen3mode
author_rank: Newbie
timestamp: March 02, 2021, 12:07:54 pm
content: Hi,I'm currently designing a small dev board that will have three power sources. They will be the battery, USB, and Vin. The problem is that all of these power sources will be connected to an LDO. The USB and Vin will be able to charge the battery which as I said airlier will also be connected to the LDO. Thanks in advance to anyone that helps.

author: Zero999
author_rank: Super Contributor
timestamp: March 02, 2021, 01:25:38 pm
content: What voltages are the?Simple diodes can be used to connect multiple power supplies together, with the one with the highest voltage, supplying the current, but there will be a volt drop of at least 0.6V to 0.3V, depending on whether silicon or Schottky diodes are used.An ideal diode controller IC can be used with a MOSFET, for lower voltage drop.https://www.google.com/search?client=firefox-b-e&q=ideal+diode+controller

author: Cen3mode
author_rank: Newbie
timestamp: March 02, 2021, 01:51:39 pm
content: The voltage range is from around 3V to 5V. So the diodes should cut it, right? The 0.6V drop is not a big deal for me. Thanks for the reply.
Switching power supply design question - Page 1
Forum section: electronics / projects

author: torch
author_rank: Frequent Contributor
timestamp: May 20, 2016, 01:39:43 am
content: Does the mains voltage and frequency affect the power output of a fixed voltage switching power supply with an input specification of 110 - 220VAC?Specifically, I bought some from China specified to be 15W, but can only deliver 10W when supplied with 60Hz 117VAC. Before I complain, I want to make sure it's not possible that they can deliver 15W if supplied with 50Hz or 220VAC.

author: jeroen79
author_rank: Frequent Contributor
timestamp: May 20, 2016, 02:52:17 am
content: What happens when it draws 10W at 110V? Does it just shut down? Or does the voltage drop?It would draw more current at 110V so perhaps that is the problem?

author: ZeroStatic
author_rank: Contributor
timestamp: May 20, 2016, 04:15:54 am
content: The power output of a 15W supply designed for 110-220VAC should be 15W regardless of supply voltage and frequency as long as it is within the specified range.117VAC is within the range specified.You should complain.

author: torch
author_rank: Frequent Contributor
timestamp: May 20, 2016, 03:08:28 pm
content: Above 10W, the voltage begins to sag, the product of VDC x A remaining about 10W.11.8 * .88 = 10.410.2 * 1.01 = 10.37.36 * 1.28 = 9.42Rated current is 1.25 amps. Above 1.28 amps the unit shuts down.As an experiment, I fed it through a variac that could supply up to 144VAC. The current available without voltage sag did increase slightly -- to 920 mA @12.2VDC or about 11W. I have no way to experiment with the frequency at mains voltage levels.Note that I was using a pure resistive load (decade resistance box). The resistors are only rated 5W, so I was keeping it brief to avoid overheating. Nevertheless, there was some variation as they warmed up, so the numbers are approximate.

author: Ian.M
author_rank: Super Contributor
timestamp: May 20, 2016, 03:31:27 pm
content: Input frequency wont make a lot of difference and a higher frequency may even be preferable if the design has insufficient reservoir capacitance on the primary side DC bus.Remember: Chinese Wattage and Amparage ratings are likeSears horsepower, but generally more optimistic!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 20, 2016, 10:13:31 pm
content: Yup, it's poo.Traditional ratings are inclusive, i.e., over X input range, Y output range will always be available. There may be additional Y available for some values of X, but we don't care.It seems likely that, in this case, they tested one combination and said "ship it". As a result, you get a conditional range instead.Tim
Switching power supply, output ripple - Page 1
Forum section: electronics / projects

author: staze
author_rank: Frequent Contributor
timestamp: November 04, 2014, 12:24:10 am
content: All,In my quest to diagnose issues with my Roomba, I noticed that there's a pretty significant ripple on the output of the switching power supply/charger when loaded down to 1.25A output. Opening the thing up, I noticed there's CapXon caps in there (ugh).I would assume the output cap is responsible for smoothing that ripple out, but I'm unsure if upping the capacity of that cap, or just putting a lower ESR cap in there, would do much to fix the ripple. Any thoughts? Is there somewhere else I should look?Kinda crappy (cappy?) that Roomba's cost as much as they do, yet they cheap out on the power supply.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 04, 2014, 01:18:28 am
content: What problems are you having?Ripple probably isn't a big deal if the problem is charging the battery, though I suppose there's a chance the charge controller might not be happy with it, or something.You can certainly try high quality capacitors, but do mind the control loop is probably designed to accommodate the high ESR; it may oscillate (squeal or hiss, perhaps at frequencies you can't hear) if you substitute something literally "too good".Mechanics, and how much engineering they can commit to optimizing the producibility of it, dominates the cost I'm sure.Tim
Switching power supply question. - Page 1
Forum section: electronics / projects

author: kvresto
author_rank: Regular Contributor
timestamp: December 18, 2014, 06:30:18 am
content: Hi.I’ve been following TI’s design examples, and plugging in numbers into WEBENCH (Vin=9V to 20V, and Vout=15V@1A), and have settled on a SEPIC design using the LM3478, but I have a couple of question I was hoping to get the answers to.The data sheet writes that since the presence of an inductor at the input of the SEPIC converter, the input current waveform is continuous and triangular. WEBENCH simulation seems to indicate that the input voltage does in fact have a couple of millivolts Vripple pp. My question is can I filter this so as not to interfere with other cct’s connected to the input, in this case the battery on a vehicle. Will a ferrite and cap do the job? or other? Seems a pissy amount of ripple??The data sheet for the LM3478 also recommends for applications that require very low output voltage ripple, a second stage LC filter often is a good solution. Apart from sizing this correctly, my question is the frequency of the ripple I will be filtering against is obviously the regulators switching frequency, but is there a trap here? or is that it?Thankskv.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 18, 2014, 01:12:21 pm
content: How does Webench simulate the source? An ideal voltage source allows zero ripple by definition.A typical automotive equivalent (LISN: line impedance stabilization network) is an ideal source, followed by an inductor terminated to 50 ohms. The cutoff frequency is modest (I forget if it's 500kHz or a bit over 1MHz?). This may yield quite a bit more 'spiky' ripple than you are expecting.Yes, the usual solution is additional LC filtering. Pick a cutoff frequency more than a few times below the switching frequency, and an impedance comparable to the ESR spec of your capacitors, so the filter is well damped by itself.Tim

author: kvresto
author_rank: Regular Contributor
timestamp: December 18, 2014, 07:02:47 pm
content: Hi T3sl4co1l, how do you think I should go about filtering the front end of my power supply in general, or is it worth the trouble?kv
Switching pre regulator - Page 1
Forum section: electronics / projects

author: OM222O
author_rank: Frequent Contributor
timestamp: July 23, 2020, 09:30:39 am
content: I have always used just a battery and a LDO in applications where noise is inportant but obviously battery and LDO means really awful battery life and low effeciency overall.I would like to implement a switching pre regulator , followed by a filter (ferrites and capacitors) and then the LDO. I have searched quite a bit on google but didn't find anything other than control the output of the regulator with something like a dac or digital pot but that's not ideal.Is there a way to have the output of the LDO in the feedback loop of the pre regulator so adjusting the output of the LDO, automatically adjusts the switching regulator?

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 23, 2020, 12:24:31 pm
content: Yes, look atLT3080 datasheet, p.21,'Adjustable High Efficiency Regulator'.You need only a Mosfet, and that's it. You use resistive feedback divider circuit of a DC/DC 'prereg' as it is, and just add a Mosfet Drain-Sourse in parallel to this feedback divider of a DC/DC regulator, and gate with series resistor to the linear (LDO) regulator output.I used this way to make a XL4016 as pre-regulator for LM350/LM338. Works fine.

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 23, 2020, 12:36:11 pm
content: If I'm not wrong I used usual 2N7002 Mosfet, it gives about 2.5-4 V voltage drop. So for low-drop LDO regulator you may need some logic-level (low-level) Mosfet.

author: hugo
author_rank: Regular Contributor
timestamp: July 23, 2020, 03:58:58 pm
content: TP0610 is a p channel mosfet and 2N7002 a n channel one ... you could be wrong

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 23, 2020, 04:17:52 pm
content: Oh, yes. It was BSS92.

author: David Hess
author_rank: Super Contributor
timestamp: July 23, 2020, 11:31:56 pm
content: Quote from: OM222O on July 23, 2020, 09:30:39 amYes, that can be easily done. However first I suggest reading the Linear Technology application notes written by Jim Williams about low noise switching regulators:https://www.analog.com/media/en/technical-documentation/application-notes/an70.pdfhttps://www.analog.com/media/en/technical-documentation/application-notes/an101f.pdfhttps://www.analog.com/media/en/technical-documentation/application-notes/AN118fb.pdf

author: Pawelr98
author_rank: Regular Contributor
timestamp: July 24, 2020, 01:20:27 am
content: Classy TL494 can do that because the error amplifiers can be tied to anything you want.With a bootstrap circuit (just like the LT part has) and a proper driver it should be able to drive mosfet switch and provide decent efficiency.

author: Marco
author_rank: Super Contributor
timestamp: July 24, 2020, 05:49:18 pm
content: Why not a PNP to have a little easier to predict drop?
Switching Regulator minimum output voltage question - Page 1
Forum section: electronics / projects

author: asifjahmed
author_rank: Newbie
timestamp: January 21, 2016, 03:46:45 pm
content: Hello! This is my first post in this forum!I am designing a custom board and am currently focused on the power supply. I am trying to use a Rohm BD9G101G (http://www.mouser.com/pdfdocs/bd9g101ge-2.PDF) due to its relatively low cost.Here are my design specs:Input voltage: 6.6 - 33.6 VOutput voltage: 3.3 VOutput current (RMS): 250 mAIn the data sheet, it says that the minimum output voltage is based on the minimum on pulse, which is around 100nsec. According to my calculations, this means that I cannot achieve 3.3 V if the input voltage is > 22 V. However, in one of their application notes (http://rohmfs.rohm.com/en/products/databook/applinote/ic/power/switching_regulator/bd9g101g_brd_appli-e.pdf), they have a reference circuit with 3.3 V out and 24 - 40 V in. Can someone please help me understand this better?Apologies in advance if I didn't provide all the necessary info. Any help is much appreciated!Best,-asifjahmed

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2016, 05:40:23 pm
content: Lower duty cycle is possible due to pulse skipping operation. Ripple will be higher and stability will be poor, however.If you need a large ratio of Vin/Vout, consider using a tapped inductor or a transformer, and a controller or topology suitable for that method (i.e., forward or flyback converter, rather than buck/boost).Tim

author: rsee
author_rank: Contributor
timestamp: January 22, 2016, 03:04:23 am
content: If you are into power supplies and want a little more theory, there is a multiple part course on coursera by the guys at University of Colorado, Boulder. I can't vouch for that particular course series, but I did go through some of the lectures when there was only one offering. Erickson did a great job explaining concepts I had been asking myself for awhile. Also, Erickson's book is on sale from the publisher for nearly half off. I picked up my copy two days ago and I'm super excited to dig in!

author: asifjahmed
author_rank: Newbie
timestamp: January 22, 2016, 03:24:31 am
content: Thanks Tim.My target voltage range is 6.6 - 33.6 V. So I don't necessarily need a large Vin/Vout ratio in all cases. Also, one requirement is low cost.Is using a switching regulator in pulse-skipping mode a bad idea?

author: jwm_
author_rank: Frequent Contributor
timestamp: January 24, 2016, 06:31:43 am
content: How efficient do you need to be? You can drop the input to 20v max with a linear regulator and do the rest with your switcher. Will need a heart sink, but nothing absurd.
Switching regulator Voltage Drop (Drop in TO220 style) - Page 1
Forum section: electronics / projects

author: ZeroAviation
author_rank: Contributor
timestamp: September 07, 2017, 11:36:31 pm
content: All,I am somewhat new to regulator design. Doing some research on a easy, self contained drop in regulator for a project.I am testing a VXO7805-1000, which is a 5v, 1A, TO220 style switching regulator . DataSheet ->http://www.cui.com/product/resource/vxo78-1000.pdfFrom what I understand about regulator design in general, is that the regulator is supposed to keep the voltage constant as long as you stay under its current limit.However, on this specific unit (and I have tested 2 others from same manufacturer), when I apply any load over 200ma, the voltage drops considerably.VIN = 13.5VDCNo load = 5.040V500ma = 4.762V1A = 4.475VThis much of a voltage drop will cause issues in my circuit.I have the recommended 10uF/50V on the VIN/GND and 22uF/10V on the VOUT/GND.Is this much of a voltage drop expected even under the rated current output? Or am I just not regulator smart?Thanks in advanceMatt

author: ajb
author_rank: Super Contributor
timestamp: September 08, 2017, 02:38:50 am
content: That much of a drop is definitely out of line with the specifications of the regulator. How do you have it connected, and how are you loading it?

author: David Hess
author_rank: Super Contributor
timestamp: September 08, 2017, 04:28:35 pm
content: I agree with ajb. The load regulation specification is +/-0.6% from 10% to 100% which is only 30 millivolts and you have exceeded it by at least 10 times. Something is wrong.What kind of capacitors did you use for the 10uF input and 22uF output capacitors? The application notes say to use ceramic which strikes me as odd without an explanation. This is even weirder since ripple is specified with a different capacitor configuration of a 10uF electrolytic and 1uF ceramic which is more in line with that I would expect to be required.Have you measured the input voltage across the input capacitor as the load is increased?Is the output voltage oscillating beyond the ripple specification of 75mV or 100mV at low load?How did you assemble your circuit? The input and output capacitors need to be attached with a minimum lead length.
Switching regulator with overcurrent shutdown.  Check my design. - Page 1
Forum section: electronics / projects

author: snarkysparky
author_rank: Frequent Contributor
timestamp: May 19, 2025, 07:18:52 pm
content: I need to drive a very small motor at a variable speed that will be selected by an on board potentiometer.Needs to be a switcher so no big heat sinks needed.Current threshold is not required to be precise.No microcontroller is planned.Should shut the motor down until a power reset in the event of a locked rotor or other mishap. Fires are not welcome.I looked for IC with this built in but cannot locate anything.I came up with this. R6 carries the main load current. If drop across it gets enough to turn on Q2 it should latch itself on via Q3 and let the ON/OFF of LM2576 go high ( shutdown).Needed power components for LM2576 will be placed but are not part of the schematic.Will this work? Any better ideas ?
Switching Regulator - Page 1
Forum section: electronics / projects

author: Christopher
author_rank: Frequent Contributor
timestamp: February 14, 2014, 02:13:53 pm
content: I have designed a simple buck regulator using the LT 1616.Specs:- 12V in to 3.3V out.- 25mA-100mA Minimum load, 500mA maximum load.I have designed a simple test board from the "typical implementation" on the first page of the datasheet which I'll route out some point next week. As Dave says, never trust these things.I've already simulated it with load stepping and it seems fine... But, I will be changing C4, C6 and L1 depending on what my supplier has in stock, as Linear always seem to choose Inductors which are not common!I'll be putting load stepping from min to max in on the board, so I can see what the transient response is with different caps (I have done this before. I work with Switching regulators on a daily basis, just don't design them!!)C4: TAIYO-YUDEN TMK316BJ105C6: TAIYO-YUDEN JMK316BJ106MLD1: ON SEMICONDUCTOR MBR0530D2: 1N4148L1: SUMIDA CR43-100So what I want to know:- How's the layout?- Is the FB voltage being tapped off at the right place? Something's rinigng in my head saying it should be tapped off closer to the output cap/ the output??- When choosing another inductor for L1, what are the specs I should be trying to keep the same? What specs aren't as important?- When I move this into my circuit, can the bottom layer (Blue) be tied straight into my main ground?Reading app notes on my day off today.... Maybe I'll answer some of my own questions...Thanks for your time :-)
Switching Small Transformer with a Triac  - Page 1
Forum section: electronics / projects

author: Cyberdragon
author_rank: Super Contributor
timestamp: February 02, 2018, 12:53:20 am
content: I want to replace the power switch of a device with a traic (BT-136, no heatsink) + opto-isolator circuit I salvaged to control it directly from an RPi. I don't know the exact load (I don't have a power meter), but the fuse is only 500mA, and the wires look to be 24 or 26 AWG.Will I still need a snubber? If so what values should I use?

author: james_s
author_rank: Super Contributor
timestamp: February 02, 2018, 01:27:47 am
content: It's rarely a bad idea to use a snubber, but you likely can get away without it. I suggest looking at the datasheets for opto coupler triac drivers, they typically will have some application notes.

author: Benta
author_rank: Super Contributor
timestamp: February 02, 2018, 02:44:31 pm
content: If you have the option to synchronize turn-on with the mains voltage, it's a good idea to switch the transformer on at peak mains voltage (or 90 degrees if you like).Switching on a zero volts usually drives the transformer into saturation.

author: Cyberdragon
author_rank: Super Contributor
timestamp: February 03, 2018, 03:41:16 am
content: Just a standard snubber seems to work fine, the triac stays cold.
Switching SMPSU inputs with a relay - inrush issues? - Page 1
Forum section: electronics / projects

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 18, 2023, 03:22:51 pm
content: Looking at a potential project that needs to switch the supply to a mains (110 or 230V) SMPSU, likely in the 200-500W range. We have no control over which PSU will be used but likely to be reasonable quality.Looking at pros/cons of mechanical relay vs. SSR, and concerned about the effect of inrush on relay life. need to have an expected lifetime of the order of 5-10K operations ( once/day for 10 years)Currently looking towards using a mechanical relay ( 16-20A rated).With an SSR ( probably homebrewed using HV MOSFETS rather than an off-the-shelf module), we have the advantage of being able to zero-cross switch to control inrush better.Anyone with actual experience of this ?

author: johansen
author_rank: Super Contributor
timestamp: March 18, 2023, 05:53:30 pm
content: Good power supplies have an NTC resistor on the input, for a 200 to 500watt supply the inrush is on the order of 10 to 20 amps.

author: Swake
author_rank: Frequent Contributor
timestamp: March 19, 2023, 10:31:36 pm
content: You could put an NTC on the output of the relay, so you're not relying on the one in the power supply that might not exist.You could implement a soft-start module.You could use a contactor for capacitive load instead of a relay. A decent one will certainly have a lifespan of way over 10000 cycles. Not expensive and exist in many sizes. No worries about certification/liability/etc... that is something you will have to deal with in a DIY situation.

author: uer166
author_rank: Super Contributor
timestamp: March 20, 2023, 02:44:27 am
content: If you're worried get an appropriate inrush-rated relay with a TV rating or similar such ashttps://components.omron.com/us-en/datasheet_pdf/J056-E1.pdf. TV-15 means it can handle 191A inrush and (edit: and 25k resistive load).A good PSU should have inrush protection such as an NTC, but if it's out of your control, better get something that'll work 100%.QuoteI would not attempt. You can do zero-cross turn on of a relay just as well with much less risk than silicon devices. Mains is a harsh environment, and even low power stuff is a much larger pain than doing it electromechanically. One trick I've used in production is over-voltaging the relay coil by 2x of rating, then economize to the proper hold voltage via PWM. This accelerates relay contact closure and makes timing more consistent, allowing you to get within 1ms of zero-cross reliably-ish.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 20, 2023, 11:16:49 am
content: Ah, thanks for the reference to TV ratings.TV-8 looks quite common and specced to 117A - thay should do fine.more info herehttps://components.omron.com/us-en/products/basic-knowledge/relays/applications
Switchmode PSU likely fault culprits - Page 1
Forum section: electronics / projects

author: SL4P
author_rank: Super Contributor
timestamp: May 18, 2014, 11:23:33 pm
content: Generic closed-frame Chinese PSU. 36V @ 2AWhat are the likely fault areas to explore - and what test methods to use when isolating the relevant component(s).(Yes - I know they're relatively dangerous to work on)

author: Stonent
author_rank: Super Contributor
timestamp: May 19, 2014, 12:12:30 am
content: Quote from: SL4P on May 18, 2014, 11:23:33 pmLook for a bad fuse, leaking or swelled capacitors, anything mounted to a heatsink. Look at burned traces, or parts of the board showing head discoloration. Make sure the transformer hasn't burned up.(Achmed beat me to the next question)But the question for you is, what kind of failure are you looking at? Completely 100% dead? Incorrect voltage output? Smoke?

author: SL4P
author_rank: Super Contributor
timestamp: May 19, 2014, 01:49:58 am
content: Quote from: AcHmed99 on May 19, 2014, 12:10:31 amGood point -not power up at all. No output, no DC on LED etc.

author: SL4P
author_rank: Super Contributor
timestamp: May 19, 2014, 01:45:50 pm
content: k - thanks
SX1276 RF layout - Page 1
Forum section: electronics / projects

author: uer166
author_rank: Super Contributor
timestamp: January 05, 2024, 09:01:45 am
content: This is my first real RF project and wanted to double check a few things:Does RF layout overall look reasonable?The dev board has a zillion vias to tie the 2 GND planes together in places other than around the coplanar waveguide traces. Is this necessary, or placing a via say every lambda/10 sufficient?Is there a reason why the dev board designers preferred coplanar waveguide vs. microstrip? I would generally prefer microstrip, but I copied the reference design as much as I could with the copl. waveguideWhile it's obvious that the impedance of the traces matched to 50-ohms should be 50 Ohms, what about the trace connecting from the SX1276 RF ports to the matching networks? The port impedances aren't 50 Ohms (otherwise there would be no matching network). Is it short enough to not matter?
SX1280: anyone? - Page 1
Forum section: electronics / projects

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 27, 2024, 11:48:44 pm
content: Just wondering if anyone here has used the SX1280 in a project, any feedback would be welcome.https://www.semtech.com/products/wireless-rf/lora-connect/sx1280
Sydney-siders - Iso Propyl Alcohol source - Page 1
Forum section: electronics / projects

author: DTJ
author_rank: Super Contributor
timestamp: September 23, 2018, 01:48:53 pm
content: I found a litre of Ethyl Acetate solvent and while finding what it was useful for I found a company called Sydney Solvents.Their prices for IPA seem quite reasonable. I figure Sydney forum members might find this useful.https://www.sydneysolvents.com.au/?rf=kw&kw=ISOPROPYL+ALCOHOLDisclaimer: I've no association with these guys whatsoever.

author: Leiothrix
author_rank: Regular Contributor
timestamp: September 24, 2018, 10:54:00 pm
content: IPA shows up occasionally on OzBargain.Here's a recent one:https://www.ozbargain.com.au/node/403396

author: NorthGuy
author_rank: Super Contributor
timestamp: September 24, 2018, 11:47:32 pm
content: I don't know about Australia, but in Canada you can buy a litre of isopropyl alcohol in any pharmacy for just few dollars.

author: DTJ
author_rank: Super Contributor
timestamp: September 25, 2018, 01:36:17 am
content: That sounds cheap, our Aussie pharmacies sell it for the equivalent of around $33/ litre.The local electronics places sell it for around $13/ litre.

author: DTJ
author_rank: Super Contributor
timestamp: September 25, 2018, 01:37:05 am
content: Quote from: Leiothrix on September 24, 2018, 10:54:00 pmThat's a very good deal!

author: Bud
author_rank: Super Contributor
timestamp: September 25, 2018, 11:44:39 am
content: Quote from: NorthGuy on September 24, 2018, 11:47:32 pmThat is a small bottle of 70% alcohol? I never seen 99% alcohol in pharmacies

author: Rerouter
author_rank: Super Contributor
timestamp: September 25, 2018, 12:09:01 pm
content: In Aus, you can generally find it in green bottles under the name "Isocol", And it doesn't appear to leave a residue when I have used it, only some moisture from the evaporation on humid days, Pricey, but available just about everywhere.However most Times I just buy 1L tins from RS Components,

author: GreyWoolfe
author_rank: Unknown
timestamp: September 25, 2018, 02:38:27 pm
content: Quote from: Bud on September 25, 2018, 11:44:39 amHere in the US, you can buy 91% IPA at CVS Pharmacy. I bought my 99% online from MG Chemicals.

author: KaneTW
author_rank: Frequent Contributor
timestamp: September 25, 2018, 02:52:23 pm
content: 99.9% Isopropanol is around 3EUR/liter in Germany.

author: Fleetz
author_rank: Regular Contributor
timestamp: September 25, 2018, 03:42:20 pm
content: What about any suppliers of a bioclean for ultrasonic baths for cleaning PCBs here in Oz?
Symetrix 528E audio processor to ham radio transceiver mic input matching??? - Page 1
Forum section: electronics / projects

author: Chris Wilson
author_rank: Super Contributor
timestamp: October 19, 2020, 08:56:01 pm
content: I want to take the balanced audio output from the XLR socket on a Symetrix 528E processor to my amateur radio 600 Ohm impedance microphone socket to allow extranal audio processing. I believe the transceiver has an unbalanced mic input. How should I do this please? The front mic socket is an 8 pin DIN, and there's another socket on the rear with mic input available, a 13 pin DIN. Do I need a 1:1 isolation transformer, or can I fudge it direct from the XLR to the DIN? Thankshttps://www.symetrix.co/wp-content/uploads/2016/02/528E_ds_EN-1.pdf
Symmetric 15v 4A power supply - Page 1
Forum section: electronics / projects

author: hendrix
author_rank: Contributor
timestamp: May 19, 2021, 01:29:29 pm
content: Hello,Im trying to build a power supply with +/-15v rails for a galvanometer with at least 3A output on each rail, 4A better. I have found some switching power supplies but most have a lower -15v amp rating compared to the +15v rail.As far as my research took me, I seem to have few options and would like to get the opinions of those that are more experienced than me.- Opt.1. Buy a Hengfu psu, model HF100W-D-L for $50 and be done with it. The problem that I have with this is the price, first of all, and the output quality.- Opt.2. Buy two 15v 4A power supplies from meanwell, model LRS-50-15, for $10 each and connect them for symmetric power. The problem with this option is I dont know how healthy this system is or can it be really considered a balanced power supply. If yes, what should I watch out for when doing this connection?- Opt.3. Make one using 7815? Lt3045 or something similar. I have found many designs for symmetric 15v power supplies but having a hard time finding one with 4A on each output that is relatively economical. Any pointers?Thank you for the help.

author: David Hess
author_rank: Super Contributor
timestamp: May 19, 2021, 08:49:43 pm
content: Quote from: hendrix on May 19, 2021, 01:29:29 pmThere is nothing wrong with option 2 as long as tracking is not required. A diode capable of handing the short circuit current should be placed across the output of each supply so that a short does not drive one of them negative, but this applies to any bipolar supply.QuoteOption 3 is the same as option 2 unless tracking is designed in. Tracking makes the outputs track each other so that they remain symmetrical which has advantages in some applications.
Symmetrical +-5VDC - Page 1
Forum section: electronics / projects

author: Tarien
author_rank: Contributor
timestamp: April 03, 2024, 05:06:44 pm
content: HelloIm looking for diagram (better single ic with some componnents) for making symmetrical +-5V out of +12VDC only. I found TPS65133 wich seems be great but 3x3mm is a barrier for me... I need to power up 16 band pass filters (about 68 op-amps) for my equalizer project so there is no need of much power. I think something about 300mA per section will be enough. I would like to minimalise my project as much i can so there is no possibility to mount classic transformer. Any ideas becouse im loosing my mind

author: tooki
author_rank: Super Contributor
timestamp: April 03, 2024, 05:44:43 pm
content: For what it's worth, the TPS65133 is a great little part. I used it in a project for exactly the same purpose as you -- powering op-amps -- and it worked brilliantly. It's not toooo hard to solder with hot air or an oven.Otherwise, you could create a virtual ground at 1/2 the supply voltage, and just AC-couple all your stages. Could be noisier, however.You can buy off-the-shelf DC-DC converter modules that output ±5VDC, e.g. CUI PQDE6W-Q24-D5-T (screw terminals), XP Power IR1205S (through-hole), Mean Well DPBW03F-05 (through-hole), or Traco Power TEC 3-1221 (through-hole). Each of these is capable of 300mA and costs under $15.You could also consider using a converter with a little higher output voltages (like Mornsun E1207S-2WR3 with ±7.2V) followed by some good linear 5V regulators to give you nice linear post-regulation to get rid of residual switching noise from the DC-DC converter. This DC-DC converter is only $3, but only 139mA, so you'd need a few of them to power your system. (I don't know whether those would allow you to parallel the outputs, so you'd probably need to use separate linear regulators on each converter.)If your op-amps are happy with less than ±5V, you could even use a ±5V converter and then post-regulate to ±3.3-4.5V.

author: Kim Christensen
author_rank: Super Contributor
timestamp: April 03, 2024, 07:56:37 pm
content: If you're powering this project from the AC line, you could simply use a center tapped transformer to build a bipolar supply.(I know you said from 12vdc, but what's the source of your 12v?)Another option is to not use a split supply at all, but rather create virtual ground at 6V for the OpAmps.

author: Smokey
author_rank: Super Contributor
timestamp: April 03, 2024, 08:30:38 pm
content: Quote from: tooki on April 03, 2024, 05:44:43 pmsame experience here. I use this for analog boards that don't have a dual supply input. Been on a number of designs now without any issues.

author: Zero999
author_rank: Super Contributor
timestamp: April 03, 2024, 08:43:58 pm
content: I would use one of those Mean Well DC:DC converters, with some additional filtering if necessary.https://www.tme.eu/en/details/dlc03a-05/dc-dc-converters/mean-well/https://www.tme.eu/en/details/dcwn03a-05/dc-dc-converters/mean-well/
Symmetricom / Microchip TrueTime - Page 1
Forum section: electronics / projects

author: cncjerry
author_rank: Unknown
timestamp: February 17, 2024, 11:47:40 pm
content: Hi,Anyone have experience with the subject unit?I bought a Symmetricom X72 Microchip 560-5203 10Mhz GPSDO Card. I wanted the X72 that is in it. I have experience with them having two. They are decent little Rubidium units that usually sell for around $300 and this was 1/3 that price. I had planned to pull the X72 out but then I started looking at the pictures and thinking, hey, if I can get power to it, the board has several SMA coaxial connectors, maybe I can get it running as a unit.You can discipline the X72 multiple ways so I'm not worried if I can't run the board. For instance, if you feed an X72 1pps, Lady Heather V6 will calculate the tuning word from a serial link and update the X72. You can then write the new tuning word to the X72 if the power fails. You can also discipline the X72 using EFC from a PLL/phase detector. I also disciplined it by setting the tuning word over a serial link instead of the EFC pin. Lady Heather will do this or an arduino, etc.The X72 has a secondary oscillator. You can send it an integer divider and output another sine wave. Depending on the crystal (30Mhz and 60Mhz are known) you can send it a '6' for instance and get 5Mhz or 10Mhz, 6 or 12Mhz for a '5', etc., respectively.The X72 runs ok off a wall wart if you insert an LT3045 in series to clean-up the power. If you need low phase noise, you can again phase lock the X72 sine output to a better oscillator as a clean-up. Unlike other Rb units I have, this one takes like from 10v to 15v or higher and doesn't need a secondary 5v for logic. My other Rb units need 24v for the lamp and 5V for the logic, but you can turn the 5v off when not needed.If you have a TrueTime, let me know. I've been searching around for schematics, etc.Jerry
Symmetricom TrueTime XL-AK Upgrade - Page 1
Forum section: electronics / projects

author: comsec22
author_rank: Contributor
timestamp: May 07, 2023, 06:35:56 pm
content: Hi Folks,I am looking for schematics diagrams for the XL-AK.. I would like if possible, to add a front panel 16x2 LCD ... and keyboard.Feeding the IRIG-B signal to an 800's series TCU (I have one).. will be a perfect pairCheers73's IU0CIXP.S. : As You see, the TCU show right time, via IRIG B, but wrong day number, should be 128 not 265 !

author: barshatriplee
author_rank: Regular Contributor
timestamp: May 09, 2023, 05:57:24 pm
content: I could only find this manual. The schematic is not open source I guess.

author: comsec22
author_rank: Contributor
timestamp: May 09, 2023, 06:12:58 pm
content: Day time number SOLVED !Just set F68 to 2004 then F79 (Warm Start) ! Done
Symmetricom XL-DC stays in unlock - Page 1
Forum section: electronics / projects

author: Evert-Jan
author_rank: Newbie
timestamp: February 01, 2020, 05:47:22 pm
content: Dear forum members,I bought a Symmetricom XL-DC. However, after connecting the antenna and switching on the device, the left display shows an A and unlock. The device is now on for over 24 hours and the antenna is in front of the window. I have checked if the antenna voltage of 5 Volt is present. The antenna I use has the following specifications: Frequency 1575.42 MHz +/-2 MHz ; Impedance 50 Ohm; Voltage 3V~5V. Does anyone have an idea what I am doing wrong. Thank you in advance. Evert

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 01, 2020, 06:58:24 pm
content: Hard to say, are the XL-DC and the antenna known to be good? What direction is the window looking at? Can you get any status info from the RS-232 port?

author: richnormand
author_rank: Unknown
timestamp: February 01, 2020, 09:16:49 pm
content: I had lots of issues with setting up a GPS antenna inside for my Trimble stabilised oscillator. I finally gave up as no window orientation was adequate.In particular since the window looked north (not many satellites there and bad elevation and a building in front)If you have an old Garmin NUVI or similar with a connector for an external antenna in addition to the internal one, it would allow you to find the best window for signal strength and number of locked satellites.Plugging the external antenna then tells you if it is working OK.These old units are available for a few $ on ebay and such. It is about the only way I had to evaluate the best antenna position.I ended up with a cheap ebay antenna with a magnet on the back. It allowed me to use a long pole (for trimming trees) to raise it and stick it high on a metal strap near the house roof looking at the azimuth.I then ran the signal coax in the corner of the window. Outside I also grounded the coax shield with another wire to ground for safety.Works great.Also my unit gives me realtime data of satellite position and signal strength via Lady Heather by Texaspyro (active member here) but no useful information until it acquires a satellite. That is why I used the Garmin initially.Antenna placement is key here.Hope that helps, good luck with it.

author: Evert-Jan
author_rank: Newbie
timestamp: February 01, 2020, 09:25:34 pm
content: As far as I know, the XL-DC and the antenna are good. I haven't figured out what information I can get out of the RS-232 port yet but I will definitely do that.Anyway, thanks for your information.

author: Evert-Jan
author_rank: Newbie
timestamp: February 01, 2020, 09:29:17 pm
content: Thanks for the tip I'm going to find out which antenna place works well. The window overlooks south, but an antenna outside seems like a promising option to me when I hear your experience. Thanks for your tip
Sync on green support on VGA monitors - Page 1
Forum section: electronics / projects

author: Axk
author_rank: Regular Contributor
timestamp: August 27, 2018, 12:22:07 pm
content: Trying to save a couple of pins on an FPGA board generating a VGA signal for my LCD monitor.OR-ing the green channel with (!HSYNC & !VSYNC) in my verilog so that when both HSYNC and VSYNC are low (active) then GREEN is high.Leaving the HSYNC and VSYNC high doesn't work with my monitor (it does work when I supply HSYNC and VSYNC, so I'm not totally off).Is this sync on green feature something that is in the VGA standard and supported by all monitors and I'm doing something wrong (leave the HSYNC and VSYNC low or floating?) or is this something that is only supported by some monitors?

author: Benta
author_rank: Super Contributor
timestamp: August 27, 2018, 05:59:43 pm
content: You cannot rely on sync-on-green in any system. Use the real HSYNC and VSYNC to be certain of compatibility.
Synchro nomenclature (RH, RL, R1, R2, Com, Line) - Page 1
Forum section: electronics / projects

author: Manul
author_rank: Super Contributor
timestamp: October 04, 2021, 02:59:04 pm
content: Long story short, I have a synchro bearing repeater (active, with amp) which was rebuilt. The aligment is unknown. I have digital synchro simulation device, reference generator, all good and ready to do aligment. But the designators for reference are like this: simulator "RH" and "RL", bearing repeater "Com" and "Line".So the question is, do you think RH = Com and RL = Line, or vise versa? Obviously, if I connect wrong, I will align the device 180 deg off. In some sources they also use "R1" and "R2" as reference designators.I hate this nomenclature and I hate these synchro systems, built before I was even born (really needed to vent).

author: jmelson
author_rank: Super Contributor
timestamp: October 04, 2021, 03:16:12 pm
content: I think RH is Rotor High, and RL is Rotor Low. It is not obvious from these labels what the right connection should be. I think you will have to dig up the manuals for these devices to be sure how they should be connected for proper phasing.Jon

author: Manul
author_rank: Super Contributor
timestamp: October 04, 2021, 03:37:13 pm
content: Quote from: jmelson on October 04, 2021, 03:16:12 pmI have no manuals, nothing at all. Searched web quite a lot about designators, but was not able to find how these different designators correlate to each other. It is not a tragedy to align it 180 deg off, client can just switch reference wires, but still it would impact my credibility to send them "inverted" bearing repeater.
Synchronize ADC with PWM on a PIC microcontroller - Page 1
Forum section: electronics / projects

author: JJalling
author_rank: Unknown
timestamp: May 29, 2014, 01:44:42 pm
content: Hi,I'm trying to do some back-EMF measurement with a PIC microcontroller (PIC 18F46K22), but i'm having some trouble on figureing out how to synchronize the ADC with the PWM signal.Idealy i want to measure the back-EMF voltage whenever the PWM signal is low, with a certain delay.Do you guys have an idea on how I can sync the ADC with the PWM signal to measure the Back-EMF?Thanks in advance.BR Jonas

author: msr
author_rank: Regular Contributor
timestamp: May 29, 2014, 01:51:58 pm
content: If the microcontroller you are using doesn't provide any internal mechanism to do that (ie, configured through registers) maybe you can use one pin with the Input Capture function? The PWM output will be connected to that pin so an interrupt is generated whenever a high-to-low transition is detected.

author: JJalling
author_rank: Unknown
timestamp: May 29, 2014, 02:36:41 pm
content: Idealy I want to create an interrupt whenever the ADC conversion is done and then just add the result to an array.Br Jonas

author: fcb
author_rank: Super Contributor
timestamp: May 29, 2014, 03:52:50 pm
content: Quote from: msr on May 29, 2014, 01:51:58 pmMSR's solution is possible (CCP5 can be used to trigger an AD conversion), although you'll have to understand the limitations this will impose on your PWM. Alternatively, you could use a free PWM module and drive the ADC with this (via CCP5), this would allow you to change the phase of your ADC dynamically (maybe useful if you are looking at back-EMF and need to get past all the switching noise).Personally, i'd use something from the dsPIC33 range.

author: JJalling
author_rank: Unknown
timestamp: May 30, 2014, 04:18:38 pm
content: Hmm. So if I understand it correct, you suggest I use the CCP5 as a free running trigger for the ADC?I think the dsPIC33 is a bit overkill for this application. And it doesn't have an internal EEPROM

author: dannyf
author_rank: Super Contributor
timestamp: May 30, 2014, 04:51:05 pm
content: QuoteSure.One way is to use an isr on that pwm generator, triggered at start time. In the isr, you can trigger the adc;Another is to use the pwm output pin to trigger external interrupt or pin-change interrupt and in that isr, you trigger the adc.BTW, timer input pins work for the last approach as well....

author: retrolefty
author_rank: Super Contributor
timestamp: May 30, 2014, 05:01:57 pm
content: The R/C hobby electronic speed controllers (ESC) also use back emf sensing to control the PWM driven attached motor's speed. Atmel was an early popular chip (mega8 I think) for that application and I seem to recall Atmel publishing some application notes for this application. Perhaps a search for them might be helpful?