hybridfree/eevblog-posts huggingface dataset:
Near 100% efficiency PSU - Page 1
Forum section: electronics / projects

author: german77
author_rank: Regular Contributor
timestamp: July 28, 2018, 12:34:57 am
content: I want to create a PSU that is at least 98% efficient. Just for fun. Even if that is only at a specific voltage and current. Let's say 150w at 24v, ripple voltage should be lower than 50mV, mains it's 120VAC. There is no budget, size or time limit.Even if my goal it's not meet. It will be a nice experience to see how efficient I can go.The main losses should be in the bridge rectifier, the mosfet, and rectifier diodes. Were should I start, any considerations I have to make before I start designing it, how you will improve efficiency?For now I will focus in making a simple switched PSU based on a meanwell PSU design, because it's already good.

author: CopperCone
author_rank: Super Contributor
timestamp: July 28, 2018, 01:34:03 am
content: what kind of response time ?in theory you want to minimize switching losses with low frequency, but obviously there are limits of absurdity

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 28, 2018, 01:51:26 am
content: If you don't care about power factor, you can just use a voltage doubler. Would still need active rectification since a diode drop out of 120V is quite significant at such high efficiency!

author: BrianHG
author_rank: Super Contributor
timestamp: July 28, 2018, 02:37:23 am
content: Quote from: blueskull on July 28, 2018, 01:37:44 amYou would have to think along the lines of powering up the control on the 120v, then switching that power source over to a 5v secondary side and switch open it's 120v fire-up side. This complicates the switching transformer with an additional isolated secondary, but, you would no longer loose the heat in that 115v drop to power the switching controller. It would also need to be a little nasty multiple transistor/mosfet 0 load switch circuit, but, it is easily doable.Getting the gate speed down might mean a lower frequency switcher still using egan devices which usually excell in the higher frequencies.98% is still too close to the edge. Maybe 96-97%. Also, I am saying 96-97% at 150watt load. At 20 watt load, the efficiency will still be high, but crap by comparison.
Near end of life electrolytics - Page 1
Forum section: electronics / projects

author: jitter
author_rank: Frequent Contributor
timestamp: May 20, 2024, 06:25:19 am
content: Recently I came into the posession of a decommissioned Alstom MiCom P127 protection relay (nowadays branded as Schneider).It had been in continuous use in a distribution station for over 20 years protecting 10 kV power lines and it was still fully operational.Curious as to how well the BC 136 RVI (now Vishay/BC) electrolytic caps had survived, I took them off the PCB and measured capacity and dissipation factor at 100 Hz and compared them to the values in the dataheet (https://www.vishay.com/docs/28321/136rvi.pdf).They were all still comfortably within specifications, especially dissipation factor being still way better than the specified max. E.g. one 2200 uF/10 V cap measured 0.094, specified max. is 0.21. Capacity was also higher than expected at 2.09 mF.This didn't tell the whole story, though, as I noticed some tiny amount of residue on the PCB where these caps had been touching it. It was nowhere else to be found on the PCB and invisible when the caps were still in place.But only under a microscope could I see that these things were actually leaking past the seal, but only on the negative terminal.I cut the two 2200 uF/10 V caps open, one is in the attachments, and found nothing out of the ordinary. For comparison, I cut open a new cap from my stash of the same series and size (albeit 470 uF/50 V), and about the same age, and found only slightly wetter foil when unwound.There was so little electrolyte in there that it would not have continued to leak. I wonder how degradation would have progressed if the relay had been continued to be used, but I guess the preventive maintenance didn't come a moment too soon (given the application).

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: May 21, 2024, 03:33:32 am
content: The two aging modes for electrolytic capacitors are loss of electrolyte (capacitance goes down, and ESR/loss tangent degrade rapidly) and oxide layer degradation. As oxide layer degrades, the capacitance actually goes up and the voltage rating goes down. So there are competing aging processes regarding the capacitance value.Leaking is a definite call for retirement though. It won't be in spec for much longer

author: jitter
author_rank: Frequent Contributor
timestamp: May 22, 2024, 05:13:36 am
content: Thanks for your explanation. I guess at some point there will be a snowball effect starting to take place, obviously, that had not yet happened in this device.
Near-THz Sub-Harmonic Mixers (Tektronix 75 - 140GHz) Tutorial, Teardown & Exp. - Page 1
Forum section: electronics / projects

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 13, 2023, 03:36:08 am
content: You can watch the video here: [49 Minutes]youtu.be/1XJvA6rwlB0In this episode Shahriar takes a deep dive into near-THz sub-harmonic mixers. To demonstrate the concepts, measurements and teardowns a set of Tektronix Sub-Harmonic mixers have been acquired (WM 490-F & WM 490-W) which operate from 90-140GHz & 75-110GHzrespectively. This video is organized as follows:00:00 - Introductions00:50 - Acquired near-THz sub-harmonic mixers & diplexers01:26 - Theoretical background, non-linear devices, harmonic generation06:05 - Spectrum analyzers utilizing sub-harmonic mixers, signal ID08:27 - Tektronix sub-harmonic mixer design, schematic & principle of operation15:11 - Mixer diode characterization using Keithley SMUs & I/V tracer application19:59 - Mixer teardown, analysis and microscope view of THz diode28:07 - Diplexer architecture & characterization using a 4-port Siglent network analyzer33:24 - Complete near-THz down-conversion setup using a x6 mm-wave multiplier source and Tektronix MSO68-B oscilloscope, conversion loss, harmonic number verification, signal ID process45:35 - Using a ~100GHz carrier to determine the RPM of a optical chopper48:15 - Concluding remarkswww.TheSignalPath.com/Donatewww.Patreon.com/TheSignalPathwww.YouTube.com/TheSignalPath​​​
NEC EA2 style relays for audio? - Page 1
Forum section: electronics / projects

author: iampoor
author_rank: Frequent Contributor
timestamp: November 14, 2015, 09:05:48 am
content: HiMy favorite relays, the NEC EA2 are being discontinuedI am looking for a suitable 5v or 9v relay for switching low voltage and low power audio signals (no more than 18V). Anyone have any recommendations? It doesnt have to be pin compatable with the EA2, I just need to design new relays in pretty soon before my next PCB order.Thanks!
need 10KVp-p amplifier to study for my theme - Page 1
Forum section: electronics / projects

author: colinhnu
author_rank: Newbie
timestamp: July 24, 2018, 07:09:12 am
content: My theme is to design a 10KVp-p amplifier.input: AC5Voutput： AC5KVBANDWIDTH: 1KHZ(-3db)slew rate: about 100V/usoutput current:≤3mAI have already design a AC1KV amplifier,i created the circuit and do some pspice simulations.10KVp-p amplifier design is a hardwork for me . Votage is so high, and i never study the amplifier like this voltage.I find a brife induction about high voltage amplifier from TREK. They use CASCODED MOSFET'S way to create the amplifier.Can anyone give me some suggestions, or post some amplifier circuits above 5kvp-p. Critical componets are necessary.Thanks.

author: colinhnu
author_rank: Newbie
timestamp: July 24, 2018, 07:44:45 am
content: thank you . I saw this article before. I will try to creat the circuit according to the principle of the circuits present in it.

author: Gyro
author_rank: Super Contributor
timestamp: July 24, 2018, 08:56:07 am
content: I suppose it would be cheating to use a standard amplifier topology and a step-up output transformer? It's been done for electrostatic speakers for decades.

author: dmills
author_rank: Super Contributor
timestamp: July 24, 2018, 09:37:14 am
content: Surely the way to do this is to deploy old school vacuum fets? All kinds of robust, you are unlikely to kill them, and 10kV is well within reach if you use the big transmitting types.Hell, give then sufficient air thru the anode coolers and a butch enough power feed and an AMP at 10kV is perfectly possible.Regards, Dan.

author: N2IXK
author_rank: Frequent Contributor
timestamp: July 25, 2018, 01:04:20 am
content: Quote from: dmills on July 24, 2018, 09:37:14 amYep. I was thinking that the high voltage beam triodes (Types 6BK4, 6EL4, etc.) that were once used for HV regulation in color TV sets would be perfect for this kind of high voltage, low current application.

author: Zero999
author_rank: Super Contributor
timestamp: July 25, 2018, 03:13:00 pm
content: Quote from: Gyro on July 24, 2018, 08:56:07 amYes, that's how I'd do it: use a standard audio amplifier, followed by a suitable transformer.
Need 12 volt SPDT Analog Switch IC - Page 1
Forum section: electronics / projects

author: rcbuck
author_rank: Frequent Contributor
timestamp: February 07, 2021, 01:57:08 am
content: I need to switch a 100 kHz sine wave that is in the 8-10 volt range. The switch should be SPDT and run at 12 volts. Switching speed should be less than 700 ns. I am trying to replace a CD4053 part with a smaller package. The switch needs to be a SMD part. On resistance can be anything under 600 ohms.I can find plenty of parts that run at 5 volts but there seems to be very few parts in the 12 volt range. The part needs to be $1 or less in cost. The only thing I have found is a MAX4544. The part needs to be available from Mouser or Digi-Key if possible.Any help is appreciated.
Need 2p connector with switch contacts  - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: April 29, 2020, 05:53:57 pm
content: I have a project to add a footswitch to a machine. The connector for the footswitch needs to disconnect the normal front-panel switch and also switch another separate circuit.So a 2-pole plug and a 2-pole jack that can switch 2 circuits. 1 circuit can be one of the plug’s poles. The other switch circuit needs to be isolated. Both circuits are 24vdc, low mA circuits.What comes to mind is a 1/4” audio headphone jack that switches the audio normally going to a speaker. But not a 1/4” audio jack. (c;Suggestions?Thanks.

author: FenTiger
author_rank: Regular Contributor
timestamp: April 29, 2020, 06:12:38 pm
content: Can you use a 4 pole plug, with two poles for the footswitch and the other two shorted together?Then the shorted contacts can operate a relay inside the machine and switch whatever you like.

author: iXod
author_rank: Frequent Contributor
timestamp: April 30, 2020, 01:16:37 am
content: OK, thank you for that suggestion. I'll go with it. 4-pole, 2 dedicated to switching a relay.Any recommendations for a 4-pin plug that isn't a threaded (MIL-type) connector? I keep going back to the 1/4" phono plug because it goes in deep and won't fall out and it's not a screw-in type. Of course this plug won't work here, but any such alternatives that are "deep" (actually go past the panel in this fashion)?Thanks.

author: themadhippy
author_rank: Super Contributor
timestamp: April 30, 2020, 02:10:45 am
content: What you got against the common ole garden jack plug?For years they were used to shove more than 24v and a few mill amps up speakers.There are 4 pole variants (nato 671),if however both foot switches could share a common wire you could get away with the more standard 3pole device.

author: FenTiger
author_rank: Regular Contributor
timestamp: April 30, 2020, 03:25:20 am
content: I'm a fan of these Mini XLRs.I'm not sure they'd be the best idea for a footswitch though. What happens if (when) the user accidentally treads on the cable? I think the common jack plug might handle this better.Do you need all 4 poles? If one side of the switch is grounded or powered, maybe you can combine it with one of the relay poles and get away with only 3.
Need +/- 3.3 volt supply - Page 1
Forum section: electronics / projects

author: scott216
author_rank: Regular Contributor
timestamp: March 17, 2014, 12:04:38 pm
content: I have a circuit where I take the output from a current transformer and convert it to a 0-5 VDC signal that goes to an Arduino. The circuit that does this uses a LM325D op-amp and needs +/- 5 volt supply. To provide this supply I'm using a MAX1044. I've attached schematics showing both the op-Amp circuit and MAX1044 circuit. All this works great, but I am am changing my Arduino that accepts 5 volts inputs to one that accepts 3.3 volts. For the Op-amp circuit, I think I can just change the supply voltage to +/- 3.3 volts instead of 5 volts. But I'm having more trouble finding something that will give me the +/- 3.3 volts. Any suggestions? I know I could put voltage divider on the output of the op-amp to lower the voltage going to the Arduino, which is what I'll do if I can't find a better solution.

author: Psi
author_rank: Super Contributor
timestamp: March 17, 2014, 12:09:24 pm
content: 3.3v linear reg on the 5V then feed that into the MAX1044 to get +/- 3.3V ?

author: mariush
author_rank: Super Contributor
timestamp: March 17, 2014, 02:04:25 pm
content: If you want something cheaper, use a MC34063 to invert 5v to -3.3v.. or make it -5v and then a linear regulator to get -3.3v .. total to about 1$ compared to a $3-4 max1044mc34063 calculator example:http://www.nomad.ee/micros/mc34063a/

author: scott216
author_rank: Regular Contributor
timestamp: March 17, 2014, 06:02:26 pm
content: Quote from: Psi on March 17, 2014, 12:09:24 pmThat's a good idea. For some reason I had it in my head the MAX1044 was 5 volt only, but that's not the case.
need 6.5v and 9v from a battery. whats the best way? - Page 1
Forum section: electronics / projects

author: dequo
author_rank: Contributor
timestamp: August 17, 2010, 07:26:02 am
content: I need to run an arduino at 7-12v, and two servos at 6.5v from a single battery.i will probably be using a battery made for remote control cars at around 7vthe arduino will only use about 20mA but the servos will use up to 0.6A eachi have been looking at traco voltage regulatorshttp://www.tracopower.com/General-Purpose.215.0.htmlbut i was hoping there was a cheaper and simpler way?

author: Simon
author_rank: Unknown
timestamp: August 17, 2010, 11:38:30 am
content: why do you need 12V for the arduino ? look like you can power the lot from 7V I can't see 7V doing a lot of harm to the servos but you can always put a diode in series with them

author: dequo
author_rank: Contributor
timestamp: August 17, 2010, 12:02:19 pm
content: i need the voltages to remain constant over the life of the battery charge. this is for a university project, i dont think they would appreciate me disregarding the servos rated voltage

author: saturation
author_rank: Super Contributor
timestamp: August 17, 2010, 01:55:57 pm
content: A cheap and simple way is use 2 battery packs, one for 7-12, another for 6.5. It not elegant but its fast and cheap.You make your own battery pack out of 1.2V NiMH x 10, the top of the pack is 12V and tap at the 5 -6 cells for lower voltage.If you need stricter voltage regulation you'll need a voltage regulator for each, as needed.if you need compact elegance, then a single battery pack supply with a regulator feeding each of your demands, but if you don't need that yet, why go there and spend more, unless its part of the class exercise.

author: Simon
author_rank: Unknown
timestamp: August 17, 2010, 04:28:49 pm
content: well I suggest using a higher voltage battery and a couple of buck SMPS's say 12-14 V, if your battery is 7V nominal and you want guaranteed 6.5 constantly, 7V is to close for most regs and it will soon fall to near 6.5V, so you need to start higher to ensure you always have enough voltage to make the most of the battery

author: Unknown
author_rank: Unknown
timestamp: August 17, 2010, 08:25:38 pm
content: There are some LDO regulator with very low drop-out voltages, they use a MOSFET pass element. But I don't think they will handle 12V input voltage, most top out at 5.5-6V.How about a buck or buck-boost converter to 9V and an LDO for 6.5V? Or a separate buck converter for 6.5V if the servo's draw lots of current. There are some easy to use switchers (eg. National Simple Switcher series) that need almost as few external components as a linear regulator, the only extra component is an inductor, and sometimes a diode.

author: Simon
author_rank: Unknown
timestamp: August 17, 2010, 08:47:27 pm
content: the big question here being is a higher voltage battery allowed ? if it is it makes life easier and more efficient

author: dequo
author_rank: Contributor
timestamp: August 17, 2010, 09:09:28 pm
content: thanks guys ill read into this stuff in the morning. and yeah the battery has not been chosen yet so it could be any voltage really
Need 9-Pin MicroSD Connector Info - Page 1
Forum section: electronics / projects

author: Gopika
author_rank: Newbie
timestamp: October 06, 2025, 06:26:59 am
content: Hi everyone,I need help identifying this 9-pin microSD card connector footprint. I’m looking for either the exact part or a compatible alternative.MicroSD Card Connector Details:- Pin count: 9 (8 + 1)Footprint Dimensions:- A = 2.8 mm- B = 4.7 mm- C = 14.5 mm- D = 9.74 mm- E = 1.1 mmI have attached:1. A top-down image of the footprint on my PCB with dimensions.2. The pinout diagram of the connAny suggestions, part references, or datasheets would be greatly appreciated.Hope to hear from someone soon!

author: jc101
author_rank: Frequent Contributor
timestamp: October 06, 2025, 07:31:01 am
content: This is pretty closehttps://www.we-online.com/components/products/datasheet/693071020811.pdfWurth have CAD libraries for a number of PCB designer tool, so it should be easy to pick up a footprint and compare directly on the board.

author: Alinik
author_rank: Contributor
timestamp: October 06, 2025, 08:00:29 am
content: From the footprint size, it probably refers to the Same Sky MSD-1-A component.Here you can find its datasheet:https://www.mouser.it/datasheet/3/6118/1/msd-1-a.pdfAnd here you can see the footprint:https://componentsearchengine.com/part-view/MSD-1-A/Same%20Sky
Need a cheap 3-20VDC in, 5VDC out 50mA - Page 1
Forum section: electronics / projects

author: envisionelec
author_rank: Frequent Contributor
timestamp: December 08, 2014, 01:54:48 pm
content: I am working on a cost sensitive project for myself that requires a tiny power supply that can output 5V with a 3 to 20V input, 20mA. Maximum (and unlikely) current draw would be 50mA. Operating temps can be as high as 100*C. The devices I'm finding are in the $1.00 range and I need the whole BOM to be about $1.00.What are some crafty ways I could make this work? Maybe a boost regulator with an LDO?

author: splin
author_rank: Frequent Contributor
timestamp: December 08, 2014, 03:19:25 pm
content: If efficiency is not important, the cheapest device I can see that is spec'd to 100C is the MC34063EB @ $.21 (1K+ fro Digikey), maximum voltage of 40V and typical start-up voltage of 1.5V at 25C . Max start-up voltage is not specified strangely but surely must be below your 3V minimum i/p voltage, (less minimum voltage drop of pre-regulator below - perhaps .3V).Use a couple of PNP transistors and a zener diode to limit the input voltage to below 5V, with the MC3406 boosting that to 5V. Select i/p limit to ensure MC3406 can always regulate the output properly. The series pass transistor will potentially have to dissipate up to (20V - limit voltage) x 50mA/(boost efficiency) mW. Say 50% efficiency and 4V limit voltage => 16V * 100mA = 1.5W max.Crude but cheap? You do the calculations though! Should easily get the BOM below $.5.

author: envisionelec
author_rank: Frequent Contributor
timestamp: December 08, 2014, 05:07:08 pm
content: Quote from: splin on December 08, 2014, 03:19:25 pmYes! Perfect!Another illuminating example of why this IS the best EE board on the planet.

author: envisionelec
author_rank: Frequent Contributor
timestamp: December 09, 2014, 01:48:06 pm
content: After reviewing my design, I decided to use the MC34063 in a buck (step-down) configuration only. The reason being that the circuit from which this regulator is driven always has a peak voltage of 12V, minimum. The lowest that it can drop on a continuous basis is 9V and the absolute minimum is 5V at which point there is no harm in the 34063 dropping out as the function of the remaining system will have been lost, anyway. I will not need the boost capability.Again, thank you very much for your input. I've characteristically been a person that doesn't ask for help very often due to some poor experiences earlier in life. I'll be a lot more participatory now.

author: tom66
author_rank: Super Contributor
timestamp: December 09, 2014, 03:10:22 pm
content: If you can tolerate the loss in a regulator, you only need to dissipate 0.75W, which is easily done in e.g. a DPAK or SOT223 or SOIC with larger copper pours.MC34063A is a pretty horrible converter, from a noise and regulation point of view. It also requires more passives compared to other regulators.
Need a fast industrial output driver IC, high-side mosfet. - Page 1
Forum section: electronics / projects

author: Leicester
author_rank: Newbie
timestamp: November 29, 2018, 09:43:25 am
content: Hi everyone!I'm designing a rotary encoder for a CNC spindle. My sensor outputs A/B/Ref in differential signals which I process into TTL. For the output I need a high-side switch that can switch 24v at very fast speeds (<10uS)... Currently on my prototype there is a ITS41K0S-ME-N which is way too slow, have not thought about that when I initialy designed the circuit. I use this "smart" thingy because it is protected against practically everything.Do you know anything similar but much faster? I'm struggling...Thanks for any help!/Leic

author: Benta
author_rank: Super Contributor
timestamp: November 29, 2018, 01:04:11 pm
content: You'll probably have to build it yourself.All the "smart" high-side switches I know are pretty slow.

author: jfiresto
author_rank: Frequent Contributor
timestamp: November 29, 2018, 02:24:02 pm
content: Almost all intelligent, automotive/industrial high side switches that need few external parts, such as the ITS41K0S you considered, have output delay times on the order of 100 µs – at least, as of a few years ago, when I looked.If you can find room for a few more passives, the Infineon (International Rectifier) AUIPS7221RTRL is a couple orders of magnitude faster. Mouser is the first distributor I could find that currently has themin stock.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 29, 2018, 02:41:36 pm
content: How about the LTC7003?https://www.analog.com/en/products/ltc7003.html
Need a help with a WIFI Router UPS - Page 1
Forum section: electronics / projects

author: soumyadip77
author_rank: Newbie
timestamp: January 26, 2024, 05:32:24 pm
content: Hi everyone,I was trying to build a WIFI UPS which will work on direct power and once power is gone it will switch to battery and it will charge when power is there. I had tried it by watching a diagram(Attached it) found on YT. But after adding everything the resistor mentioned got burned.Components Used3S BMSXL6009 DC-DC Boost Power Supply Module1N5822 Schottkey DiodeIRF9540N P-Channel MOSFET10K Ohm ResistorThanks guys in advance

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 27, 2024, 12:24:25 pm
content: Make sure you got a 10k resistor and not a 10 ohm resistor.

author: SeanB
author_rank: Super Contributor
timestamp: January 27, 2024, 12:32:48 pm
content: Would connect the input voltage via a diode, direct to battery pack, and let the BMS board handle the charging. Then connect the DC DC converters across the same terminals via the switch. Simpler, and so long as the wall wart supply has a maximum voltage of 12V6, and you use a schottky diode to have minimum voltage drop, the BMS will keep the battery nearly fully charged, and no need to switch over when power is lost. The one you show is way too complicated for the function, and simpler is a lot better.

author: soumyadip77
author_rank: Newbie
timestamp: January 28, 2024, 04:20:36 am
content: So you mean I don't need to use the mosfet and this many diode ? only one single diode will be connected to the input and bms connection middle? Will it auto switch without turning off the device.
Need a IoT wifi module supporting EVM board - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: April 23, 2019, 02:28:56 am
content: Hi There,Does it possible to virtual simulation of a IoT wifi module?Suggest me kindly.I am working with a WIFI module from a different company.It has JTAG interface with API, SPI protocol with main MCU and UART as well.Take a look the image below.Kindly find a suitable EVM to support it in case of IoT.I will provide all information relating to this project.Following facilities are required...1. USB to serial driver.2. Serial terminal utility.3. Wifi Mode setup4. Setup soft mode5. Command line interface6. Consol command
Need a LM393 with a non-inverting output. - Page 1
Forum section: electronics / projects

author: Hootis Tigglebits
author_rank: Contributor
timestamp: January 09, 2024, 11:20:07 pm
content: I have an IR detection board that I'm running 5VDC to. When nothing is sensed the output of the LM393 is high and when something is sensed the output is low. I need the output to be the opposite of the way it currently is. How can I find out if there's a replacement for the LM393 in an 8-SOIC package that uses the same input pins and has a non-inverting output? I know I could just use a NOT gate at the output, but I'd rather do this correctly.

author: mawyatt
author_rank: Super Contributor
timestamp: January 09, 2024, 11:36:37 pm
content: Swap the LM393 Inputs.Best,

author: tggzzz
author_rank: Super Contributor
timestamp: January 09, 2024, 11:39:28 pm
content: Try swapping pins 2 and 3.

author: Benta
author_rank: Super Contributor
timestamp: January 10, 2024, 12:40:41 am
content: Bad design, BTW.Both inputs to the comparator can be forced outside their operating voltage range.

author: pqass
author_rank: Super Contributor
timestamp: January 10, 2024, 02:04:57 am
content: If you can't swap the input pins 2 and 3, then the next best thing is to invert the output with a transistor (rather than a NOT gate).Just add an NPN; existing D output to NPN base, emitter to ground, collector is your new output. Note that his arrangement only allows you to "sink" current from the new output. If you need to "source" current, then use a PNP instead; existing D output to PNP base (through a series 1K resistor), emitter to Vcc, collector is your new output.You could implement either via lifiting the pin(s) and "air wiring" a transistor[+resistor]. I doubt you'll find a '393 equivalent with swapped inputs or inverted output.See below andhere for the simulator.Note: quirk of the sink driver has the on-board LED always on.

author: Hootis Tigglebits
author_rank: Contributor
timestamp: January 12, 2024, 07:02:28 pm
content: Thank you!
Need a simple power on delay circuit - Page 1
Forum section: electronics / projects

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: May 09, 2019, 02:44:24 am
content: Hi,I have a device that is powered by +20VDC at about 125-150mA. I need to add a circuit that once it senses the +20V has been turned on, delays the delivery of the +20V to the device for 2 Seconds or so. I don't want to use a relay. Is there a simple MOSFET high side switch circuit I could adapt?Cheers,Corby

author: TomS_
author_rank: Frequent Contributor
timestamp: May 09, 2019, 12:49:20 pm
content: Quick and hacky circuit attached. Not particularly elegant, and you might want to make sure that it doesnt output some kind of spike immediately after turn on.Q1's gate is held high via R1 while R2-3/C1 forms an RC circuit which holds Q2's gate low until C1 charges sufficiently, thus turning Q2 on which pulls Q1's gate low allowing voltage to flow.Otherwise there are things like processor supervisors which might do a lot better since they have voltage comparators and output delays built in. Some of these wont give 2 seconds of delay, but there are some out there which can use an external RC circuit to provide any delay you want (e.g. TL7705A). You'd just need to use something like a resistor divider to power it from a more acceptable voltage level.Perhaps there are other better voltage monitor circuits out there that someone may come up with.

author: ajb
author_rank: Super Contributor
timestamp: May 09, 2019, 03:16:48 pm
content: You can skip the n-channel FET and flip the RC circuit over to save a couple of components if you're okay with a slow rise time. You'll want a diode in parallel with R2 (cathode to V+) to ensure that C1 is discharged quickly on power off, otherwise you won't get the right delay after a short power blip.

author: OM222O
author_rank: Frequent Contributor
timestamp: May 09, 2019, 03:20:43 pm
content: is the circuit always outputting 20v or you need to sense that 20v is present, then delay it?RC circuit can't actively monitor the voltageI know it's very common with USB-C powered devices that they have to monitor it because the voltage can be either 5 or 20 volts, depending on what device is connected.

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: May 11, 2019, 02:05:31 am
content: Thanks for the ideas!I've some parts coming and will breadboard the circuit and play with it.Cheers,Corby
Need a SMPS solution. - Page 1
Forum section: electronics / projects

author: Boscoe
author_rank: Frequent Contributor
timestamp: May 25, 2015, 06:16:35 pm
content: So I need a compact SMPS for a project of mine. Space is at a premium and so I need to design it myself and integrate it onto my PCB ideally.Requirements:- Switch frequency 100kHz<- Two rails at 28V 2A each.- Low noise (good enough for audio).- Small.- 230Vrms input.- PFC unnecessary.The system is going to have a standby 3V3 rail so I'm thinking I could use that rail to drive a quick MCU or a small FPGA to use as the controller, I could I have a fast ADC in there too. The I use a gate driver IC from IR and design myself a small transformer. Easy? Not sure, I've never designed a SMPS before, I've always avoided it, but I'm capable.I would prefer to use an off the shelf IC but they all seem quite outdated and don't usually have 230Vrms operation reference designs.Thanks

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 25, 2015, 06:37:26 pm
content: Have you looked into the Power Integrations switcher chips? That said, you'll be better off using off the shelf solutions whenever possible.

author: DanielS
author_rank: Frequent Contributor
timestamp: May 25, 2015, 06:41:32 pm
content: Doing an AC-DC converter as your first SMPS attempt seems excessively ambitious and kind of dangerous.If you want a minimum component count solution, look at things like the TOP250. That device has nearly everything you need for the primary side of things. As far as noise goes, you can take care of most of that with a Pi-filter but then that means more space on the power supply board.

author: Boscoe
author_rank: Frequent Contributor
timestamp: May 25, 2015, 06:42:56 pm
content: Quote from: NiHaoMike on May 25, 2015, 06:37:26 pmThey look interesting. I am quite biased towards doing my own for experience etc. It looks fairly straight forward with the difficult bit getting it safe and reliable. This part scares me because I want to be able to use it in my house without having to turn it off all the time.

author: Boscoe
author_rank: Frequent Contributor
timestamp: May 25, 2015, 07:04:40 pm
content: Their information is good and there's software tools!
Need a specific breakout board - Page 1
Forum section: electronics / projects

author: AussieBruce
author_rank: Regular Contributor
timestamp: March 09, 2025, 12:43:08 pm
content: Hi, I need to go from a ribbon cable IDC connector to a row of screw terminals. There are plenty of breakout boards around, but all of them seem to be for hosting a specific microcomputer, or for DB connectors. My one needs to connect to a custom device.My application needs around 20 screw terminals, all low current and preferably on the small side. A link to a supplier (with a hobby level MOQ) would be much appreciated. Thanks in advance.

author: themadhippy
author_rank: Super Contributor
timestamp: March 09, 2025, 01:25:27 pm
content: something likes?https://www.winford.com/products/brk2x10.php

author: moffy
author_rank: Super Contributor
timestamp: March 09, 2025, 08:48:59 pm
content: Or you could design your own PCB to suit your project, it is quite inexpensive these days with JLCPCB, PCBWay etc.

author: AussieBruce
author_rank: Regular Contributor
timestamp: March 11, 2025, 08:09:25 am
content: Spot on, thanks lot!
Need a verifiable schematic for the PLJ-0802F - Page 1
Forum section: electronics / projects

author: joe burch
author_rank: Newbie
timestamp: June 03, 2024, 05:26:11 pm
content: Hello folks,Once again, I'm looking for a copy or a link to the above frequency counter. Someone was nice enough to send me a schematic of a 'comparable' unit using a PIC16F628A, but that is not what I need. I've searched the web and saw several references here about folks possessing a copy and that they had made refinements to the actual circuitSo please, if someone has either an actual copy of a link to the schematic please let me know. I have the revised code almost all done (works on the 6 digit LED version) and I don't want to have to trace everything out on the board.Thanks - in advance - for anyone's help.
Need a Watchdog - Page 1
Forum section: electronics / projects

author: steerex
author_rank: Newbie
timestamp: September 18, 2020, 01:29:18 am
content: Hey Guys,I have reached a point in my life where I need an electronic "watchdog". I live a hermit lifestyle and due to some heath conditions, I'm afraid of something happening and not being unable to notify anyone. The things I'm concerned about are things like a stroke, a diabetic coma, or slip and fall. The kind of events that leave one unable to make a call or trigger an alarm manually.What I'm considering is a device that would automatically sound an alarm and/or flash a strobe after a set period of time (perhaps 18 hours). If the device was not reset in that time frame, it would initiate an alarm. I envision a reset button somewhere in the house that would send a wireless signal to the device and reset the watchdog.There are a couple of considerations:There are many trees on my property so for visibility the device would be placed on a pole alongside my drive about 100 yards from the house. That makes it more visible for the neighbors. Because of the terrain running power and comm cables to the device is not a good option. Thus the need for wireless communication. It would also need to be battery powered with a solar charging system.The communications could be one-way and work like the remote door locks on a car. Press a remote button and it beeps to acknowledge the reset signal. So, what I'm looking for is suggestions about the best comm technology for this project. What are the options for a low cost, low current draw receiver, that will work reliably at 100 yards. I'm very comfortable with programming AVRs so a module that'll easily interface would be best.Thanks, Steve

author: nuclearcat
author_rank: Unknown
timestamp: September 18, 2020, 02:29:51 am
content: Are you sure they will be interested in helping? If yes, then you can ask them and send message directly to their phones (push notification/etc).If they don't, they will just ignore your alarm, or wont understand what is that.And 18 hours or any hours is totally useless in case of saving you. If you want to be saved, get apple watch or any other such watch, they have such functions.If you want to go DIY way, you can use TTGO wristband or watch (or two, if one is on charge, you wear another one) and write your own firmware.They can react if you stopped moving and not reacting to alarm, or have abnormal heartbeat. (They have accelerometer, heartbeat sensor, etc)
Need Advice: Current Mode DC Converter, or Voltage Follower into a Resistor - Page 1
Forum section: electronics / projects

author: TheRuler8510
author_rank: Regular Contributor
timestamp: February 13, 2015, 01:46:44 pm
content: Advice Needed:I want to generate a constant 500 mA that limited to 12V out. I want to use a 6V battery to do it.Any ideas on the best way? I could use a boost converter and use a voltage follower & MOSFET into a 1 ohm resistor, like Dave did in his current source. Or I could use a current mode DC-DC converter.Any ideas on a better way? Is there a current mode converter that would do it? Please suggest a chip to do DC-DC conversion for this.Any suggestions are welcome.Thanks in advance,
Need advice on a bubble memory investigation - Page 1
Forum section: electronics / projects

author: FrankenPC
author_rank: Unknown
timestamp: March 08, 2014, 11:12:59 pm
content: Hello.So, I bought this old Fanuc (Hitachi) bubble memory board on Ebay on a whim. I thought it would be interesting to figure out how bubble memory worked and try to make it work again in a micro controller project. I believe this is generically called the HItachi BMU 64 bubble memory board used in Fanuc CNC systems. Unfortunately, the bubble modules are only hand labeled and Google turns up squat. Anyone have any hints on where I can get info on this? Maybe a maintenance manual for the BMU, or a white paper on the architecture? Thanks for your help!Some pics.http://imageshack.com/a/img547/9850/6x7t.jpghttp://imageshack.com/a/img36/8575/sooj.jpghttp://imageshack.com/a/img36/6637/7ovf.jpghttp://imageshack.com/a/img31/9489/1frb.jpg

author: FrankenPC
author_rank: Unknown
timestamp: March 08, 2014, 11:47:28 pm
content: Located the Intel 7110 1Mbit bubble memory module which most physically resembles the no-name chip in question. Indeed the x and y coils seem to match up with the unidentified chip. But, alas, not mush else seems to match the pin out.http://www.decadecounter.com/vta/pdf2/7110.pdf

author: SeanB
author_rank: Super Contributor
timestamp: March 09, 2014, 06:39:42 am
content: I had the Intel databook on those at one time. Might still have it around.

author: mistertransistor
author_rank: Newbie
timestamp: April 06, 2014, 02:17:47 pm
content: I can help a little, but I don't have data I'm afraid.Firstly, that card should have two Hitachi 64 Kilobit bubble memory modules on it - your images seem to only show one. You can tell what these old cards hold from two things - firstly the 'BMU 64-2' part of the number, and secondly the labels on the shielding plate.64 Kbit was first generation bubble memory, it's quite old. The Intel 7110 is 1 Megabit, so has quite a different pinout. The closest equivalent you could try searching for is the TI part TIB0203, but it is 92 Kbits.However, what do you hope to do with it? That whole card, including the LSI controller, is just dedicated to driving up to 4 of those modules. You won't be able to breadboard something yourself! You might be better trying to get data on the Fanuc bus that it connects to, and use the whole card that way.

author: FrankenPC
author_rank: Unknown
timestamp: April 06, 2014, 04:34:01 pm
content: Quote from: mistertransistor on April 06, 2014, 02:17:47 pmThanks for your response. I came to the same conclusion and gave up on the unit. The driving electronics are too complicated for my level of knowledge. I was hoping to build a USB memory storage unit with it. I'm going to go with ferrous core memory instead. It's FAR simpler in operation.
Need advice on a e-bike project.  - Page 1
Forum section: electronics / projects

author: eatmorepizza
author_rank: Newbie
timestamp: September 17, 2015, 01:05:09 am
content: Hello all and thank you for viewing. I'm working on a fun project for my kids and I wanted to get some advice/info for this build.I have received a free MX-350 razor Dirt bike and I've decided to upgrade the components. The stock system is 24v controller with a 350 watt motor and 2-12v 7ah lead acid in series. I'm heavy into many hobbies and have an abundance of lipo packs and single cells as well.So first order of business was to purchase a new controller that is capable of handling 36v and an upgraded motor. That's the easy part. What I need help with is designing a Lipo management system for the lipo cells.The configuration will be 2 sets of - (9) 5000mah cells in series (33.3v-37.8v) and then in parallel doubling the capacity to 10ah.On eBay I've found lipo pcm boards up to 7 cells only so I'm left with either (6) 3 cell lipo pcm or single cell pcm for each cell. I need help crunching some data. These lipo pcm units have amp ratings and I needed help deciding which would be appropriate.Projected data -36volt500 watt motorThat would pull roughly 14ampsIf I were to use a single pcm on eac lipo rated at 5 amps would that remain 5 amps throughout the output leads or will it multiply?Thank you.

author: eatmorepizza
author_rank: Newbie
timestamp: September 20, 2015, 10:34:40 pm
content: Anyone?
Need advice on filtering current clamp signal - Page 1
Forum section: electronics / projects

author: mike buba
author_rank: Contributor
timestamp: November 08, 2021, 04:12:44 pm
content: Hi,I need advice on filtering a current clamp signal. I am using aPico TA167 200 A / 2000 Acurrent clamp (BNC connector) and a Rigol DS1054 oscilloscope. When I am measuring 2-3 A (on the lower range (200 A)), the signal is full of noise.I know, I should have gotten a 20 or 30 A probe, but this wasthe cheapest from PicoI could find, and at the time of buying I didn't know about manufacturers like Hantek or Tecpel and Tektronix was too expensive.Now I am stuck with a 200 A probe and need to measure only up to 20 A.

author: bob91343
author_rank: Super Contributor
timestamp: November 08, 2021, 07:16:26 pm
content: Perhaps you can characterize the interfering signal. It might be a local broadcast station or similar.

author: CaptDon
author_rank: Super Contributor
timestamp: November 09, 2021, 02:12:57 pm
content: First thought, Wind the conductor 10 times through your clamp. Now your 200A clamp becomes a 20A clamp. Now have a look at the noise/etc. If the noise is real then it should be factored as a 'real' component and not filtered out. 20khz interference?Sounds like a SMPS very close by, like even the one inside your scope? Or possibly your LED/CFL lighting?
Need advice on how to properly manage Data channels on USB desktop device. - Page 1
Forum section: electronics / projects

author: ItsRickss
author_rank: Newbie
timestamp: February 02, 2024, 09:14:13 pm
content: Hi everyone! First time here, I'll try to be as clear as I can. I apologize for bad english in advance.I'm developing an ESP32-based desktop device which measures power consumption of different devices connected through it. It uses a INA219 sensor to measure power. It has 4 different input (IN) and output (OUT) connectors (USB Micro, USB-A, USB-C and a T-Block), IN voltage is short-circuited between all of the IN connectors, then it goes through a fuse, to a Shunt Resistor of the INA219 sensor, and then through another fuse towards the OUT connectors.Power measurement works, it displays and saves the data of any device connected through it, but I wanted to allow the device to work as a "passive, non-interrupting data device", i.e. I wanted it JUST to interrupt the power source channel, and leave the rest of the Data channels intact, allowing the device to be recognized by my computer, or to allow Fast Charge from a charger, which I understand works by using the Data channels.For that purpose, the ESP-32 and sensors attached to it work either independently or parasitively from the power source, and the D+ and D- channels of the USB jacks are uninterrumpted between the IN and OUT connectors.I just tested the device and it works (yey! it measures power being consumed) BUT when I connect my cellphone through the device to my computer (USB_A COMPUTER -> USB_C Device IN -> USB_A Device OUT -> USB_C Cellphone IN) it doesn't recognizes the cell. Fast Charger doesn't work either.I thought that by only interrupting the power supply, there would be no issues of Data being transmitted, but I really don't know much about USB comm. protocols. Also I am ignorant of the issues of changing from USB types (from USB "A_to_C", then from "C_to_A" and finally from "A_to_C" again)I'd appreciate any input on how to apporach this issue. I attach a picture of the basic schematic of the device.

author: magic
author_rank: Super Contributor
timestamp: February 02, 2024, 11:00:10 pm
content: If the only thing you have done is inserting a small resistance in series with Vbus, this shouldn't be a problem unless output voltage drops below 4.75V.Perhaps an issue with D+/D- connections, then? How exactly are they made? Are they shorted together between multiple connectors of different type?USB 1.1/2.0 needs a straight differential pair, without branches and with constant 90Ω (IIRC) wave impedance from the host all the way to the device. It will tolerate some degree of sloppiness, but not a lot of it.
Need advice on remapping quite a few inputs/outputs. - Page 1
Forum section: electronics / projects

author: Pasky
author_rank: Regular Contributor
timestamp: April 22, 2015, 04:22:58 am
content: So my project will involve me taking logic inputs and mapping them in any configuration I want to 40 5V logic outputs. I know a CPLD can do this but I don't think any exist with 40 inputs and outputs. I'd also level shifters as most fpga's/cpld's are now 3.3V and not 5V. Would this be the best way to do this? Are there any CPLD's out there that can take 40 inputs and also has 40 outputs? Re-programming it I would like to rely on USB so I'd need a USB controller as well I suppose. I'd like to avoid muxers and the like to allow to reduce the input/output requirements on the CPLD as I'd like the board to be as small as possible as well with as few parts as possible since the concept is extremely simple.Am I going about this the wrong way or am I on the right track here? Thank you for any help and/or advice you can supply!
Need Advice - Power Conversion Question - Page 1
Forum section: electronics / projects

author: rfdes
author_rank: Regular Contributor
timestamp: September 14, 2020, 12:20:16 pm
content: I have a need for a 35VDC @ 120mA power supply which needs to be created from a 28V DC supply. I've been looking at PWM boost converters but feel that there may be another option that I am not aware of. My big challenge is to keep the design footprint as small as reasonable.I would appreciate some alternative suggestions as to how an achieve this design.ThanksJim

author: Siwastaja
author_rank: Super Contributor
timestamp: September 14, 2020, 01:11:51 pm
content: Boost is simple and alright, the limitation of the simplest design being that it "leaks" the 28VDC input directly through the diode even if it's turned "off", and hence cannot provide short circuit protection; unless you add an extra protected switch.If this doesn't matter, I'm sure boost will be the smallest and cheapest. I think your spec can be achieved in about 15x15mm area quite easily.