hybridfree/eevblog-posts huggingface dataset:
High current consumption on a CC1310 - Page 1
Forum section: electronics / projects

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: September 05, 2023, 06:22:59 pm
content: Hello everyone,Currently working on a smart sensor project and I've been banging my head trying to figure out why my PCBs consume as much as they do with no obvious issues.First of all, I've attached the partial schematic of my PCB where VMCU connects. (VMCU is coming from a 3V Coin Cell)The rest of the sensors are powered by the load switch that is enabled by the CC1310.Here are some screenshots of the layout of the PCB as well. It's a 2-layer board so I've attached pictures of both layers with the VMCU net highlighted.I've been using a Power Profiler Kit II to take the current measurements of both my and the CC1310 module I used as a dev board.(The module :https://www.aliexpress.com/item/4000185596036.html?spm=a2g0o.order_list.order_list_main.10.6d931802XMCYzd(Not affiliate))The setup is pretty straightforward: I power the PCB using the JTAG header (programmer disconnected) and measure consumption while running a TI example (pin shutdown) to measure consumption.When measuring the dev board (with nothing connected to it), I get the expected 7-8uA. When I measure my PCB though, consumption jumps to around 970uA.I've tried measuring consumption with the resistor of the battery measurement divider disconnected from VMCU but as expected nothing changed (the divider is being pulled low from the MCU to take the battery level measurement)Even tried removing the load switch altogether to ensure the rest of the system is not powered.I'm currently at a loss for what might be causing the issue so any suggestion/addition is welcome.Thank you in advance.Note: There is another issue with the PCB but did not make a fuss about it here considering it should not have any effect on the consumption but might as well include it.I've got an I2C sensor that is being powered by VSNS. When power is enabled, the MCU cannot pull SCL low unless the 10K pull-up is removed from the board.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: November 04, 2023, 01:26:57 pm
content: Hello again,Just an update on my journey of lowering the power consumption of the core.I've laid out another version of the board using the smaller package (in order to size down the board).Took special care in laying out the power path for the IC considering I had the same issue with my previous board.The peripheral circuit remained the same except for the addition of an I2C ambient light sensor.At this point, I am out of ideas.With nothing but the core running, the power consumption is north of a milliamp.Any suggestions would be highly appreciated, thank you in advance.
High current LDOs: integrated or external n-fet with charge pump - Page 1
Forum section: electronics / projects

author: ezalys
author_rank: Frequent Contributor
timestamp: September 05, 2025, 02:48:16 pm
content: I have an application where I need an amp at 28 V with low noise. At these levels, there are LDOs like the LT3080 which seem applicable. Notably there are also designs using a high side n-fet and a charge pump. The stability of a common drain configuration seems pretty nice. That said, maybe this is antiquated and the LT3080 is stable enough for most applications and the absence of a charge pump is good for low noise. When would you choose one over the other?

author: PCB.Wiz
author_rank: Super Contributor
timestamp: September 06, 2025, 12:32:30 am
content: The LT3080 does not have much margin for 'an amp at 28 V' ?Power dissipation may matter more here, what is the source supply variation and ripple?
High Current Motor Driver Schematic required - Page 1
Forum section: electronics / projects

author: praveen_khm
author_rank: Contributor
timestamp: October 30, 2014, 06:58:07 am
content: Hi,I have checked around for any opensource schematic for controlling high power DC Brushed motors, but it looks like I was not able to find any. I need to design something similar tohttp://www.dimensionengineering.com/products/sabertooth2x12from dimensionengineering. Can somebody help me with links for any opensource design schematics? Even if not, any suggestions to design one can be helpful.Thanks,Praveen

author: LukeW
author_rank: Frequent Contributor
timestamp: October 30, 2014, 11:42:17 am
content: Do you need servo feedback or are you happy with just open-loop control?

author: Kremmen
author_rank: Super Contributor
timestamp: October 30, 2014, 01:13:55 pm
content: Quote from: praveen_khm on October 30, 2014, 06:58:07 amFamiliarize yourself with the functionality of the L297 / L298 stepper driver ICs. They won't do exactly what you need but once you understand what the chips contain and how they work, it will be easy to re-implement the relevant part of the functionality to drive a DC motor. Essentially it is a H-bridge with PWM current control scheme. On top of that you still need an armature voltage control circuit with its own feedback, either from a simple tachogenerator or a pulse encoder, depending on what kind of speed controller you want to have.

author: awallin
author_rank: Frequent Contributor
timestamp: October 30, 2014, 04:32:55 pm
content: Quote from: praveen_khm on October 30, 2014, 06:58:07 amH-bride designs:http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Bridges_-_Half%2C_Full%2C_Three_Phaselinuxcnc on real-time linux can close the loop in software. (fpga-card to read encoder and output pwm required for good performance. hobby-level performance might be doable over parallel-port)or here's a very simple one:http://emergent.unpythonic.net/projects/01142347802and one with a DSPic to close the loop:http://members.shaw.ca/swstuff/dspic-servo.html
high current PCB with large air coil example? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2023, 07:10:11 am
content: I saw this vendorhttps://www.coilws.com/index.php?main_page=index&cPath=208_522_551Say the 160 amp flat coil. Has anyone seen that in a device before?I wanted to see a PCB with those coils on it.Like where would it be. Some kind of converter for a high end forklift? electric car? robot arm

author: Berni
author_rank: Super Contributor
timestamp: November 30, 2023, 08:19:12 am
content: This is likely for some very specialized applications rather than just your typical switching converter inductor. Maybe for some RF uses, perhaps shaping in some pulsed applications like pumping lasers, perhaps an igniter circuit for a giant xenon lamp..etcSwitching converters for those high currents are very common actually. All the modern high performance graphics cards have a ~1.2V 300A power supply on the board to feed the GPU with the core supply voltage. But they split up that huge switching converter over many phases to make it compact enough to fit.

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2023, 09:08:47 am
content: yeah I know you start getting the same current levels in computers but I want to see what the hell actually has that expensive square big ass coil in it

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 30, 2023, 03:05:50 pm
content: Induction heater?

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2023, 05:29:50 pm
content: I meant. Value off the shelf pcb mount coil, not a similar coil. Like a component . The induction heater will have some custom stuff built. This looks like it’s on-board mountedUnless they have that coil inside? And another work coil outside.

author: twospoons
author_rank: Frequent Contributor
timestamp: November 30, 2023, 08:54:35 pm
content: We used to use an air-core inductor of a similar size and rating as part of the pulse shaping network in electric fence energisers. This was 20 years ago, so not that exact part of course - ours was just fat copper wire wound on a plastic bobbin.

author: MarkT
author_rank: Frequent Contributor
timestamp: November 30, 2023, 10:26:11 pm
content: I've seen such a coil in a ferrite core - perhaps one use of these is with stock/custom magnetic cores? Saves on the need to wind such a core.

author: wilhe_jo
author_rank: Regular Contributor
timestamp: December 01, 2023, 09:21:24 am
content: Back when I was an employee, we used these a lot, and for ages!However, these were 6layer PCBs with extra thick copper and we used ferrite coresSo mechanically the solder joints were pretty much ok for the weight.It's just cheaper than screwing ...73

author: coppercone2
author_rank: Super Contributor
timestamp: December 01, 2023, 10:48:05 am
content: what did they do
High Current Short Circuit control, 24v welder - Page 1
Forum section: electronics / projects

author: Sandman614
author_rank: Newbie
timestamp: June 05, 2023, 03:31:12 pm
content: I hope this is the right crowd for this level of techincal question. The welding forums that I've asked this on just blather like a neanderthal "Learn how to burn some 7018 rod, and take batteries out of multiple peoples trucks".I have built a portable battery powered Mig welder, but it lacks control over voltage and current. The build uses a 4p8s LifeP04 battery pack with 200a JKBMS, the wire feeder from a cheap inverter mig welder(24v feed motor) with a 5a pwm controller, a 24v high current solenoid, and 0.035 welding wire. My end goal is a portable battery welder that will mimic/enhance the practice of stick welding using 2 car batteries and a set of jumper cables, for offroad trail repairs. Generally these repairs are larger chunks of metal like tie rods, axles, and various brackets.So to the point, what I am looking for is a means to vary the amperage on a 24v DC system from 30-200amps. What I am finding are similar to the PWM motor controller I have already used but they only seem to go up to the 60a range and I don't think that a PWM controller is the correct device for the intended use. I have already tried setting the "Continuous discharge current" in the BMS but that does not seem to be limiting the current like I believe it should. My amp clamp has gone MIA so I have not had a chance to verify this yet.

author: Kryptychon
author_rank: Contributor
timestamp: June 07, 2023, 02:40:05 pm
content: Hi,what you basically need to implement/get your hands on is a controllable current chopper.I guess you can re-purpose a mains powered welding inverter to work with DC. Basically, inside a welding inverter, mains is rectified, fed into a high voltage DC bus from which in turn the actual inverter circuit is fed.Of course there is a transformer involved to achieve galvanic isolation, but that's not a concern if you're using batteries.My approach would be to get my hands to an actual mains MIG/MAG inverter and have a look into the electronics and if the DC bus can be fed externally somehow.I can imagine the DC bus voltage in an actual inverter will be much higher that your approximately 30V (8s LiFePO4), so this needs some thinking.As you have 4p8s, you could reconfigure your pack to get around 120V of DC...maybe that's a starting point. Of course, your battery pack must be fused(!) and you will need a different BMS.Be warned, if you're going down that road, the energy stored in the DC link caps of a mains powered welding inverter is substantial. It's high voltage, high amp DC - very dangerous to fiddle around with that.The same applies for a 120V battery pack.Good luck!RegardsKryp
High current switch vs slide switch + FET. - Page 1
Forum section: electronics / projects

author: silent
author_rank: Contributor
timestamp: May 25, 2014, 11:00:47 pm
content: Hello.I have two boards in my project - #1 (main) and #2. I want to be able to manually cut off the power from #2 (drains 3A in peak). Is it a good design practice to use a small slide switch and a FET (2-way ON-ON; [5V OR GND]------[base of FET] ) or should i go with a large switch with higher current rating?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 25, 2014, 11:49:35 pm
content: If there's no special reason to do otherwise, I'd be surprised if the sw+FET were even cheaper, let alone easier to do.Special reasons might include: limiting turn-on surge current or controlled ramp-down; sparkless switching (particularly for higher voltages in explosive environments); automated control, or as a future expansion option; fault current limiting; etc.Special considerations include inrush current, peak dissipation, handling of fault current, extra voltage drop, additional current draw (at least a few microamps, due to the gate pullup resistor, depending on value and speed) and etc.Tim

author: silent
author_rank: Contributor
timestamp: May 26, 2014, 12:37:15 am
content: I'd like to use a small smd switch with p-mosfet in SO8 instead placing a larger tht one. I think I'll go with FET.
High DC Voltage measurment - Page 1
Forum section: electronics / projects

author: sanwal209
author_rank: Regular Contributor
timestamp: February 12, 2018, 08:56:36 am
content: Hi,I am currently doing a project with 8 Channel HV DC measurement. I used typical topology like first main high voltage divider then instrumentation amplifier. I am getting accurate reading but it takes 2 sec for the output to settle down. It seems like there is some high capacitance but i couldn't figure it out where.PS: High voltage negative terminal is not connected to ground of op-amp.Please help me where is the problem.

author: HighVoltage
author_rank: Super Contributor
timestamp: February 12, 2018, 09:51:58 am
content: What HV source are you measuring?How high is the voltage?How stable is the source?

author: capt bullshot
author_rank: Super Contributor
timestamp: February 12, 2018, 10:02:45 am
content: Most probably the capacitance is hidden in your supply (I assume it is floating).When connecting the HV, the local ground potential has to be moved to the middle point of your HV. This involves charging the capacitance from your local GND to earth - this kind of capacitance exists everywhere and isn't located in a single component.You don't have resistors from the "+" inputs of the input amplifiers to your local circuit ground. So the charging current has to go "through" the "+" inputs of the OP-Amps - which is bad design as it won't do so as desired.You should remove R14 and replace it by two identical resistors from the respective node to HV_M_GND. These resistors will then provide the path for the required charging current. Without these resistors, the "+" inputs will settle anywhere (depending on the leakage of the amplifier inputs), most probable outside the allowed input range of the amps. The resistors will also provide the required path of the input leakage to your local GND (HV_M_GND).

author: sanwal209
author_rank: Regular Contributor
timestamp: February 12, 2018, 12:46:14 pm
content: Source is 1000V dc battery in electric vehicle. I have attached the basic architecture of the system. So we have one main battery but there are many contactors for power distribution and we want to measure voltage at different nodes in the system which includes measurements before and after contactors.Resistance of 3Mohm in architecture is actually 3x 1M resistor. @Capt Bullshot yes you are right about it. I used the exact same thing before with separate 30k resistors and ground but i changed it because when S1 is off we will still have 6Mohm resistance between node1 and node2.Another very solution would be to use 8 separate isolated dc to dc converters and have separate ground for each channel.What do you think? can we have some solution without having this separate current path?

author: capt bullshot
author_rank: Super Contributor
timestamp: February 12, 2018, 01:25:00 pm
content: If absolutely no current leakage is allowed, you'd need to isolate each sense amplifier by using it's own DC/DC converter. Otherwise, calculate your circuit impedance by maximum allowed leakage current.
High Density Distribution Blocks - or suggest better idea? - Page 1
Forum section: electronics / projects

author: klr5205
author_rank: Regular Contributor
timestamp: August 08, 2023, 12:41:57 pm
content: A little background:I've inherited a mess of a 4 axis motor controller that is used internally where I'm employed. Since it was originally built to be as general-purpose as possible, motor and feedback wires (encoders AND resolvers) are common across multiple connectors. You'd never use more than one at a time, but it depends on what is being controlled.The reason it's a mess is that many of these common connections are made in (what I consider) sloppy ways: multiple wires from different cable assemblies crimped into the same ferrule, multiple ferrules in a screw terminal, multiple wires in a solder cup. Grounding is no better, where logic reference, motor bus reference, and earth are all used interchangeably.I would love to clean these things up. I suspect ground loops being the cause of some motor driver and power supply failures these controllers have experienced. It would be nice if I could just redesign the driver pcbs to have enough I/O such that every front panel connector wire has a dedicated connector pin on the board, but I don't know that that's in the cards right now, and it doesn't help the 8 or so units currently in existence. I wonder if I can at least get the grounds organized and eliminate the terminal sharing by adding some high-density distribution blocks which brings me to my question:What are your favorite high density low power distribution blocks? I've been eying the Phoenix PTFIX series but I wonder if there are even smaller / better options to consider? I'd like to be meaningfully smaller than your typical DIN rail terminal. The wire sizes run from 22-18awg, all stranded and ferruled, except where soldered. In most cases I'd need to split one signal into 3, so 4-6 position blocks are ideal. Din rail mount preferred but not required.I've also considered making a sort of backplane / motherboard to distribute the common signals, and that would be one method, but I think an inferior one to adding the needed connectors to the motor driver pcbs, due to the extra interconnect cabling / real estate it would require.So there you have it: I'm basically trying to put lipstick on a pig, and plumbing the depths of the internet for the prettiest shade haha

author: Terry Bites
author_rank: Super Contributor
timestamp: August 08, 2023, 02:48:01 pm
content: With TS-15 DIN rail you're not going to find much smaller.Phoenix are the goto for me.You can get nice commoning bars/ jumpers for a tidy job.Have you looked at Camden Boss CTBPD96xxx?TB series from C3?I'm sure TE have something similar, plenty of knock off's on Aliexpress
High density matrix board - Page 1
Forum section: electronics / projects

author: artag
author_rank: Super Contributor
timestamp: October 29, 2023, 08:36:22 pm
content: Does anybody sell a prototyping board with 0.050" pads ?I want to test a fix for a PCB and there isn't much space. Stripboard or square-pad board would be OK but it really needs to be on 50 thou (1.27mm) pitch to take the ICs. The nearest things I can think of are the breakout boards for SMD ICs (https://www.ebay.co.uk/itm/324852323272) or Mike's high density prototyping boards (https://www.whitewing.co.uk/protoboard.html)The first is too small and the second too large (though I might get desperate and cut it up).

author: Someone
author_rank: Super Contributor
timestamp: October 29, 2023, 09:28:03 pm
content: Not so hard to find.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 30, 2023, 04:12:19 pm
content: Make your own.
High discharge current from standard 18650 lithium battery  - Page 1
Forum section: electronics / projects

author: najrao
author_rank: Regular Contributor
timestamp: July 09, 2018, 04:05:15 am
content: The first two photos show a cordless driver battery, before and after a modest top-up charge. Fortunately, I had moved it to a safe place. I had bodged five 2.8Ah pouch cells from a RC drone battery, matched for exact voltage but not protected by a BMC.The next pic shows a 20+Ah, 11.1V pack, 3S-10P. I just scored this, and want to use it for a high drain load.It has but a modest BMC, next pic. The two 4663 mosfets in series opposition are only good for a few (<5)A, as also so are the pcb tracks and lead wires fitted. I stripped the outer shrink plastic jacket to take pics.The 10P 18650's should be good for some 40A. The inter cell connections are properly welded.I propose to fit an external mosfet disconnect switch, to be tripped by the BMC itself if it detects an abnormal condition. A 12V coil relay can also be used, if the coil is not energized in standby condition. That way, the BMC will not see the high drain current. Charging at <5A can still be done via the BMC. All wiring will be made appropriate. A 40A auto fuse may be enough, but I am looking at better current limiting/ tripping.Any further safety issues? Please explain with reasoning. Thanks for your time.Please overlook the wrong order of attachments.

author: timpattinson
author_rank: Contributor
timestamp: July 09, 2018, 04:23:37 am
content: As you are using the cells as a high drain load you should really set up some kind of over temp protection.Sent from my SM-G930F using Tapatalk

author: najrao
author_rank: Regular Contributor
timestamp: July 09, 2018, 10:56:52 am
content: Given the flat layout of the 30 cells in the pack, sensing temperature of just the one or two overheating cells is not straightforward at all. Suggestions please.I do have a high current 3S BMS, from RC battery, to 50A. I remember reading that there is a right way of connecting the battery wires, all other ways being wrong/unsafe. Do the taps go in later, or what? Help please!

author: timpattinson
author_rank: Contributor
timestamp: July 09, 2018, 11:28:21 am
content: Brute force approach to temp sensing:Connect lots of diode based temp sensors (such as LM335 from ST) in parallel, they will report the highest temperature of them all. In TO-92 package you can arrange one to touch two cells, so you don't need as many.
High efficiency voltage converter out of MOSFET driver. - Page 1
Forum section: electronics / projects

author: MasterT
author_rank: Frequent Contributor
timestamp: March 02, 2019, 03:57:51 am
content: Design idea, getting step-up or inverter converters out of MOSFET driver IC.Despite commonly used topology using switch + schottky diode as a rectifier, here is another concept, one side of the MOSFET driver served as a switch, but another side as synchronous rectifier - zero lost power. Schottky diodes are there just for initial start-up.Only step-up converter proof of concept tested so far.
High frequency 24V to TTL voltage drop - Page 1
Forum section: electronics / projects

author: andrew_c
author_rank: Regular Contributor
timestamp: April 29, 2016, 03:03:20 pm
content: Hi all. I wish to use a 24V NPN PLC output to control a 3kHz 50% duty signal to a 5V (TTL) stepper motor controller. Unfortunately I need to control about 10 signals and those 24V DIN rail optocouplers are looking rather pricey.Is there a nice simple (with as few components as possible) way to drop the voltage here? I thought about simply hooking a decent 10k resistor between the two, though I suspect fires would be started? Maybe a voltage divider - or would there be too much parasitic capacitance in the resistors?Any help appreciate. Thanks in advance guys.Andy

author: Zero999
author_rank: Super Contributor
timestamp: April 29, 2016, 06:59:26 pm
content: 3kHz is slow.You could use a resistor but you'd need to connect a Schottky diode from each input to the +5V supply to clamp the input voltage to little over 5V. 10k might be too low, as the 5V power supply could rise due too the extra current being injected into it.

author: qwaarjet
author_rank: Regular Contributor
timestamp: April 29, 2016, 07:26:31 pm
content: I had a similar problemUsed a two 6k resistors as a divider and a zener diode as a clamp works over a wide range of voltages with minimum power burn.

author: andrew_c
author_rank: Regular Contributor
timestamp: May 04, 2016, 03:00:06 pm
content: Hi guys,Thanks a lot for the valuable responses. However, I was curious about using a ULN2002A darlington array? Sorry to second guess your ideas but would it work?Thanks,Andy

author: qwaarjet
author_rank: Regular Contributor
timestamp: May 07, 2016, 03:16:56 pm
content: it could work but you may need additional parts depending if the input to the drive is sourcing or sinking.

author: andrew_c
author_rank: Regular Contributor
timestamp: May 09, 2016, 01:30:28 pm
content: So, bad timing but I've just dug out the stepper motor controllers and it looks like they have built in opto-isolation. I'll have look at how much current they draw this afternoonAndy

author: andrew_c
author_rank: Regular Contributor
timestamp: May 11, 2016, 07:02:30 am
content: Okay, so I measured 16.3mA current draw for the diode @ 5V. Plonked a 1.2k resistor in there and so far everything seems to be working great! I did notice that at 1200Hz it drops to 4V - which I've compensated for, by bringing the duty cycle up from 50 to 75%. This is by far a nice, cheap, simple solution - though only because I already have the opto-isolation built into the controller.Thanks again for the help guys.Andy
high frequency dc transfomer driver - Page 1
Forum section: electronics / projects

author: croyleje
author_rank: Regular Contributor
timestamp: October 28, 2012, 05:38:20 am
content: hello everyone i am working on a high frequency dc driver for a transformer used in an xray unit. the driver feeds 160vdc into a step-up transformer which feeds a voltage multiplier. my question is i have been doing some research and have come across a few examples of using small inductors on the input to lower the resonant frequency but i haven't found any info on sizing the inductor so does anyone have any idea how to figure that out? and my other question is would alternating the polarity from +160vdc to -160vdc at frequency increase output of the transformer? does anyone know if in high frequency dc systems like these are the transformers normally pulsed or alternated?note: i have gotten the unit working and the images are exceptable but am worried about tube life.thanksjason

author: penfold
author_rank: Frequent Contributor
timestamp: October 28, 2012, 04:25:22 pm
content: It is hard to determine the answer without a bit more information on your setup, a circuit diagram would be nice.Just to clarify, where are you considering putting the inductors, are there at the input to the driver, the transformer or the x-ray tube?

author: croyleje
author_rank: Regular Contributor
timestamp: October 28, 2012, 05:40:58 pm
content: sorry i been working on this for awhile the inductor is on the transformer primary and right now i am working on characterizing the circuit now with a 10uH and 15uH inductors but iam just picking sizes and trying to plot the output to get an idea of how size effects the circuit but i would prefer not shooting in the dark. i will draw up a simple schematic when i get home and post it thanks for the help. any ideas about the switching polarity and the effect on the secondary.thank youJason
High-Frequency Low-Current Second-Order Bandpass Active Filter Topology and Its  - Page 1
Forum section: electronics / projects

author: promach
author_rank: Frequent Contributor
timestamp: September 28, 2020, 01:23:57 pm
content: ForHigh-Frequency Low-Current Second-Order Bandpass Active Filter Topology and Its Design in 28-nm FD-SOI CMOS, why the followingcmos bandpass filter circuitdoes not work ?
high frequency oscillation in a capacitively compensated resistive divider - Page 1
Forum section: electronics / projects

author: max_torque
author_rank: Super Contributor
timestamp: November 29, 2016, 08:17:34 pm
content: I'm designing a 100:1 high voltage probe. It has a relatively low bandwidth, lets say around 1Mhz (-3dB).I've got a basic design, the DC division done by 5Meg of input resistance into 50.5K to groundParallel to this is a capacitive path, with around 25pF into 2.5nF to ground.This works quite nicely, giving a reasonably flat reponse between DC and about 3Mhz. However, above that, it begins to "ring"/ oscillate, and the attenuation falls right off (reducing to roughly 20:1 at around 7Mhz). This is more than adequate for my requirement, as the circuit includes a 5th order low pass AAF with a 2Mhz knee, so that ringing will never make it to the output.But, it would be interesting to try to reduce the ringing! Currently, the capacitive path includes around 100Ohms of resistance in series to act as a damper, this is installed prior to the high capacitors. Should i perhaps try some resistance between the high and low arms of the divider to damp the ringing further into the circuit?I guess i need to do a Spice simulation, and add some parasitic capacitance/inductance and see if i can simulate the same sort of response, giving me an idea how to eliminate it?

author: Cerebus
author_rank: Super Contributor
timestamp: November 29, 2016, 09:41:50 pm
content: My first thought is, "Is your scope lying to you?". You've got a 5M source and are presumably loading it with a 10M probe - that is definitely going to affect the measurement significantly. If you had a low impedance source I'd say try a lo-Z probe before you do anything else, but with 5M at the input this isn't even a starter.Do you have, or could you beg, steal or borrow a FET probe to try?

author: Andy Watson
author_rank: Super Contributor
timestamp: November 29, 2016, 09:52:04 pm
content: Quote from: max_torque on November 29, 2016, 08:17:34 pmIt is usually the path between your scope input (the active component) and the capacitance to ground that requires the series damping resistance - obviously this will also have a detrimental effect on your bandwidth.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 29, 2016, 10:20:28 pm
content: Plot the transient or frequency response.Tim

author: max_torque
author_rank: Super Contributor
timestamp: November 29, 2016, 10:38:55 pm
content: Indeed, no, i can't rule out the influence of the scope probe! TBH, i haven't had long enough to look at it, just time for a quick look see with a std 10M probe. I might be able to borrow a FET front end high impedance probe and use that for a look. The other issue is that i'm still waiting for the opamp that is buffering this signal to turn up from the supplier, and that will obvious add significant capacitance and some impedance to ground, which will undoubtedly change the performance characteristic somewhat
High Frequency Push/Pull Switching at Output Supply Voltage of ±30V - Page 1
Forum section: electronics / projects

author: willPowell
author_rank: Contributor
timestamp: January 31, 2022, 10:44:35 am
content: I am currently using a photocoupler solid state relay with the following datasheethttps://docs.rs-online.com/02d2/0900766b81699edf.pdf?bcs-agent-scanner=5b60e31c-44b1-bc42-9e67-a9b48284643bIt works very well but I need a slightly faster switching frequency ideally at least 20kHz plus. Are there any other push/pull ±30V optocouplers that have this frequency. If not, any other ideas much appreciated.I was looking at RF digital isolators but they all seem to be logic level.Do you guys know of any that may be an appropriate substitute just with faster switching speeds (maximum of Ton/Toff of 0.05ms)?Thanks,Will

author: jonpaul
author_rank: Super Contributor
timestamp: January 31, 2022, 10:46:33 am
content: Normally a bridge is driven by a dedicated high side driver IC, or a transformer coupled driver.Search "high side bridge driver"Differnt for IGBT/FET/BJTj

author: Kryptychon
author_rank: Contributor
timestamp: January 31, 2022, 01:14:37 pm
content: Hi,have a look at the TL250H (Datasheet) from Toshiba.I used it as a MOSFET driver at 25kHz PWM. Worked fine.Addendum: Sorry, you specified ±30V. The TLP250H does not fit here :-/

author: willPowell
author_rank: Contributor
timestamp: January 31, 2022, 01:34:44 pm
content: Thank you for your response. I think I will use an Hbridge configuration with gate drivers.

author: willPowell
author_rank: Contributor
timestamp: January 31, 2022, 02:03:33 pm
content: This Toshiba photocoupler looks great - it can go up to 30V and can both source and sink current at high frequenciesFor some reason it says in recommended operating conditions that the supply voltage should be at least 10V. [See attached photo]Is this a problem as the supply voltage can go below i.e any range from -30V to +30V?

author: Kryptychon
author_rank: Contributor
timestamp: January 31, 2022, 02:49:28 pm
content: As I understand the datasheet, the powersupply can be 35V at max, recommended is 30V.The internal circuit schematic suggests, it useses a photodiode as detector, so I suppose, 30V is a safe reverse voltage of the photodiode.Never used the TLP250 with a GND below 0V, so I cannot say for sure if it supports a symmetric power supply at all. The internal schematic makes me guess it can but not between -30V and +30V as this would exceed the maximum supply voltage rating.
High frequency PWM supported LED Driver - Page 1
Forum section: electronics / projects

author: kasunch
author_rank: Newbie
timestamp: April 29, 2016, 11:36:53 am
content: Hi,I am trying to design a high current (about 700 mA) LED driver which is capable of PWM dimming. The LED driver should support higher PWM frequencies as high as 1 MHz. The purpose of higher PWM frequencies is to use LEDs as a data communication method as well as lighting.I tried a simple constant current driver using a simple liner regulator (LM350T) together with an external MOSFET. The liner regulator wastes lot of energy as heat on high input voltages in addition to the current sense resister. I also came to know that these kind of liner regulators also have a limitation on transient response time with higher frequencies.Then I looked at available switching LED drivers such as buck-boost drivers. However, supported maximum PWM frequency of them is below 100 kHz for almost all of them (looks like this is due to their switching frequency is below 2 MHz).I appreciate it very much if you can give some pointers for achieving higher PWM frequencies.Thanks.

author: ajb
author_rank: Super Contributor
timestamp: April 29, 2016, 12:57:20 pm
content: Yeah, I don't think you're going to find anything off the shelf. A quick google shows a couple of papers on LED drivers that use GaN power stages to achieve switching frequencies in the 10+ MHz range, but I don't believe there are any integrated commercial solutions yet. Parts that use Si power stages are going to top out at 1-2MHz, as you've seen. You might be able to roll your own higher frequency converter using a GaN power stage, but getting it to operate properly at such high frequencies will not be a simple task.A much easier solution is probably to do a switching pre-regulator in constant voltage mode with a hefty output capacitor and a linear constant current stage following it.
High Gain amp for pickup coil - Page 1
Forum section: electronics / projects

author: skyler
author_rank: Regular Contributor
timestamp: January 31, 2014, 03:35:39 pm
content: Hi, I'm still a beginner at electronics and I want to build an amplifier for a magnetic pickup coil for "hearing" computer noise from hard drives etc., finding the mains lines, and just to listen to audio frequency electromagnetic waves for fun to see what it sounds like.I would like a good gain control knob to listen to very faint signals when I am far away from any interference. I don't care about that fancy automatic gain control, I just would like to hear very faint signals. (i'm sorry I don't have the decibel amount, I don't know how I could find how many DB gain I would like, I just want a device which has the capability of turning up the gain to A LOT.)What practical circuit can I build that will achieve this with fairly low noise? I would like it to take voltages in the 5-12 area so standard batteries can power it, and enough power to drive a small 8 ohm speaker with adequate volume like a cheapie walkie talkie.

author: dannyf
author_rank: Super Contributor
timestamp: January 31, 2014, 03:40:28 pm
content: google instrumentation amplifier.

author: skyler
author_rank: Regular Contributor
timestamp: January 31, 2014, 06:07:54 pm
content: Quote from: dannyf on January 31, 2014, 03:40:28 pmThere's a lot of stuff I don't understand when I googled that and found some PDFs on it
High gain Transimpedance amplifier - 40 Hz noise - Page 1
Forum section: electronics / projects

author: arivalagan13
author_rank: Contributor
timestamp: April 15, 2020, 04:40:21 pm
content: I bought the OPA656 evaluation board and configured it as TIA with a gain of 10^9. Used application circuit from the opa656 datasheet.I enclosed the amplifier in an aluminium shield to avoid EMI.The amplifier is now connected to a CRO.Now, I try to disturb the amplifier with body current (since I don't have a precision low current source), the amplifier is oscillating with a square wave with frequency roughly at 40 Hz. The amplitudes of the square wave are the saturating voltages of the opamp. The system is powered with +/-5V regulator which in turn powered from two 9V batteries and no transformers are involved in the design. The power supply is enclosed in a separate aluminium shield. Both aluminium shields are professional ingress protection box bought from SparkFun.What could have gone wrong? The CRO is of analog type and with an only single trace. I checked the ground loop to my best and found to be ok with it. And by the way, for the information, the frequency at India is 50 Hz from grid power.How do I troubleshoot such a problem?RegardsM AIndia

author: tggzzz
author_rank: Super Contributor
timestamp: April 15, 2020, 04:46:37 pm
content: Quote from: arivalagan13 on April 15, 2020, 04:40:21 pmMany many things could have gone wrong.You start by providing sufficient information for us to discount the unlikely possibilities. That should include a schematic, photos of the device's interior and exterior and test setup, and a photo of the output.

author: alanambrose
author_rank: Frequent Contributor
timestamp: April 15, 2020, 04:50:05 pm
content: Probably leakage or inadvertent coupling between output and input. A small parallel capacitor in the feedback loop (maybe only 1pF) will probably fix the problem.Alan

author: arivalagan13
author_rank: Contributor
timestamp: April 15, 2020, 05:07:13 pm
content: I'll try to add one and update.

author: arivalagan13
author_rank: Contributor
timestamp: April 15, 2020, 05:08:21 pm
content: I'll update all the details.

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 15, 2020, 08:22:01 pm
content: Gain 10e9? Isn't it too much?It needs only 5 nV to saturate opamp.I think you have to lover gain to 10e6 max.

author: Marco
author_rank: Super Contributor
timestamp: April 15, 2020, 08:32:57 pm
content: Quote from: arivalagan13 on April 15, 2020, 04:40:21 pmWhat do you mean body current?Any way, the input is virtual ground ... just set a lab power supply to 0.1V and use 100 Meg resistor to get 1 nA.
High Humidity Design - Page 1
Forum section: electronics / projects

author: cwerther
author_rank: Newbie
timestamp: December 12, 2017, 07:30:58 pm
content: I'm designing some add on's for my telescope (mirror fan control, temperature sensors, etc) and depending on the time of year it can easily be operating in the 90%+ relative humidity range. Do y'all have any suggestions for circuit design for high humidity environments?

author: Benta
author_rank: Super Contributor
timestamp: December 12, 2017, 07:36:49 pm
content: Nothing special on circuit design, but conformal coating the assembly comes to mind.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: December 14, 2017, 01:21:04 am
content: Also it would be advisable to use a 'breather valve' with a semipermeable membrane so that vapour can get out. Further, use proper cable glands. Select connectors for external connections which are sealed back and front. Maybe use a heater (resistor) in the electronics too to drive any humidity out.

author: cwerther
author_rank: Newbie
timestamp: December 14, 2017, 02:31:04 pm
content: Thanks for the suggestions. I hadn't considered the breather valve. I'm not sure how I feel about just using the heater, but hey, when it works, why not?

author: coppice
author_rank: Super Contributor
timestamp: December 14, 2017, 02:37:47 pm
content: Consider connector materials carefully, as you can seldom fully seal them from the environment. For example, in modest humidity areas you might have used silver plated connectors for your RF stuff without any problems. Try putting them in a warm moist environment, like Singapore or Hong Kong, and they go black in days. Other materials may not perform as well from an RF connection point of view, but you will need to tolerate them for their greater longevity.

author: coppice
author_rank: Super Contributor
timestamp: December 14, 2017, 02:43:37 pm
content: Quote from: cwerther on December 14, 2017, 02:31:04 pmWhat happens when the heater is off? There is nothing to stop condensation then, and it might cause corrosion. What interlocks will you have, so things don't start up until the heater has had time to dry things out?If the equipment will be subject to regular inspections, you might look at trying to seal up some areas as well as you can, and put a desiccator inside. Desiccator replacement can be part of the inspection.
High impedance short in cable - Page 1
Forum section: electronics / projects

author: Rachie5272
author_rank: Regular Contributor
timestamp: November 02, 2017, 08:26:36 pm
content: I'm trying to fix a Dell laptop power supply, which is causing the infamous "AC power adapter type cannot be determined" error. Essentially, the laptop can't communicate with the DRM chip in the power supply and complains, even though the actual power rail is just fine.I've traced the problem to a high impedance short circuit (this sounds like an oxymoron) in the power cable, between the positive wire and the 1-wire data wire. Even with the data wire unsoldered from the power supply board, it still has about 5 megaohms of resistance between it and the positive wire.My guess is the internal insulation frayed a bit, even though the cable looks fine. This resistance is enough to pull the 1-wire high, and disrupt communication with the EPROM chip.Is there anything I can do? I thought about Dave's trick of using a high current power supply to let the short burn itself out, but that won't work in this case without high voltage, which is just as likely to break down the insulation.How about a megaohm pulldown resistor to counteract it? I suppose as a last resort I could transplant the EPROM chip directly into the laptop.

author: jmelson
author_rank: Super Contributor
timestamp: November 02, 2017, 08:59:16 pm
content: Look carefully at the connector end, some conductive gunk might have gotten into it. These exposed connectors on laptops get SOOO dirty, dragging around in laptop bags for years. Not sure it can be cleaned without making it much worse. Maybe you could just bake it for a couple hours at 50C and see if it temporarily improves. I think there are guys who sell just replacement cables on eBay for a couple bucks.Jon

author: Rachie5272
author_rank: Regular Contributor
timestamp: November 02, 2017, 10:04:03 pm
content: Oddly enough, despite buying the laptop and charger used, everything was astonishingly clean, including the power connector. It must have been a corporate purchase, sitting on a shelf untouched for years before being resold.I ended up bridging the 1-wire and ground with a 24 kiloohm resistor to drop the idle voltage to around 3V, and it worked. The battery charges again, and the CPU is no longer underclocked.
High impedance voltage measuring? - Page 1
Forum section: electronics / projects

author: Artlav
author_rank: Frequent Contributor
timestamp: November 05, 2014, 01:22:05 pm
content: Let's say you want to measure voltage on an 0.1u capacitor, without affecting it (much).You touch multimeter probes to it, the display flickers for a moment and reads 0V.Oops, it's discharged now.So, how can you do it?I think something like a buffer on an ultra-low input leakage op-amp might work, but maybe there is a simple trick or tool for this?

author: robrenz
author_rank: Super Contributor
timestamp: November 05, 2014, 01:41:15 pm
content: An Electrometer will typically have greater than 100 TOhm input impedance and can easily do this.

author: HKJ
author_rank: Super Contributor
timestamp: November 05, 2014, 01:52:26 pm
content: At low voltages some meters can be switched to a high impedance input.

author: dannyf
author_rank: Super Contributor
timestamp: November 05, 2014, 07:16:22 pm
content: QuoteA 0.1uf capacitor can hold far more charges than what's needed to perform an adc, especially one with high impedance input (like a digital multi-meter).If the capacitor is of very low value, like in the pf territory, you can either use a low-leakage high impedance converter to buffer it; or rely on charge transfer - only if the meter's own capacitance is known.
High input capacitance for a NOR flash - Page 1
Forum section: electronics / projects

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: August 11, 2023, 10:37:33 am
content: Friends,I was planning to use a serial NOR flash in one of my designs. I picked up the part from micron MT25QU02GCBB which is a 2Gbit part. I plan to run it at 120MHz clock rate in qSPI mode.But when I was analysing the timing requirements, I found that it has an unexpectedly high input capacitance of 35pF. How on earth could an input buffer have a capacitance of 35pF and be expected to work at high speeds..Has anyone else seen any issues with this?

author: MK14
author_rank: Super Contributor
timestamp: August 11, 2023, 11:06:14 am
content: Quote from: EEEnthusiast on August 11, 2023, 10:37:33 amNot necessarily the same datasheet as your device, but from a similar Micron device:QuoteNon-stacked ones seem to be more like 8 pF (but may not give you the desired capacity), which is perhaps what you were expecting.https://media-www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-b/mt25q_qlkt_l_02g_cbb_0.pdf

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 11, 2023, 01:52:35 pm
content: Must be some weird way of measuring, it would be impossible to drive that capacitance at 120MHz (38 ohms).
High input impedance audio amplifier ic. - Page 1
Forum section: electronics / projects

author: geggi1
author_rank: Frequent Contributor
timestamp: October 07, 2014, 03:39:13 pm
content: Can anybody recomend a input high impedance IC to build a audio amp.The output of the amp can be less than 1W.The input impedance will have to be close to 10 Kohm.

author: Farley
author_rank: Regular Contributor
timestamp: October 07, 2014, 07:38:36 pm
content: Take a look at the TI TPA711. According to its datasheet, the application circuit shown on page 23 has an input impedance of 10k.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 07, 2014, 07:43:48 pm
content: 10K is not "high impedance" to most audio people. It is probably the average input impedance of MOST typical audio amplifier circuits.Most people would think of something more like 1M as "high-impedance". Typically for things like vintage passive e-guitar pickups, etc.Furthermore, any higher impedance input can be made "10K" with the trivial addition of aseriesparallel resistor.Thanks for the correction, Wiss.

author: wiss
author_rank: Frequent Contributor
timestamp: October 08, 2014, 10:25:10 pm
content: ... parallel ...