hybridfree/eevblog-posts huggingface dataset:
How to design a current limited 35W DC/DC converter, 24Vin to 350Vout - Page 1
Forum section: electronics / projects

author: AndersJ
author_rank: Frequent Contributor
timestamp: August 06, 2018, 11:35:17 pm
content: Any suggestions on how this can be done?

author: Evan.Cornell
author_rank: Regular Contributor
timestamp: August 07, 2018, 09:00:31 pm
content: Using Power Stage Designer (http://www.ti.com/tool/POWERSTAGE-DESIGNER), it looks like a standard boost should be realizable. At a quick glance, LM3478/LM3488 look like they could be suitable controllers for external FET.For current limit, it may perhaps be easier to implement on the input side, using something like ADI's (formerly LT) SurgeStopper parts.What is the application?

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 07, 2018, 09:01:28 pm
content: Hack a cheap inverter?

author: AndersJ
author_rank: Frequent Contributor
timestamp: August 08, 2018, 07:05:42 am
content: QuoteCharging large high voltage capacitors.

author: strawberry
author_rank: Super Contributor
timestamp: August 08, 2018, 10:14:27 am
content: SMPS need to have CC(constant current) to charge capacitor or series resistor 200R..1k to limit inrush current.1k resistor will give you 350mA instead of ~100ADont forget about ear plugs and safety glasses

author: Mazo
author_rank: Regular Contributor
timestamp: August 08, 2018, 12:55:40 pm
content: Hysteretic control of inductor current(or forced BCM/DCM) and probably a tapped inductor(1:1 is easy to get off the shelf and will do the job) is the simplest/cheapest solution I can see.And the 350V part-just gate the driving signal.Frequency of switching will vary wildly!Alot of tricks possible but complexity goes up and the charm of this simple approach is gone.You get a power limit this way not a current one but should do the job?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 08, 2018, 01:44:36 pm
content: Hi,The LT3751 is designed for this application:Link:http://www.analog.com/en/products/power-management/switching-regulators/flyback-forward-isolated-controllers/lt3751.html#product-overviewLink:http://www.analog.com/media/en/dsp-documentation/evaluation-kit-manuals/dc1322A.pdfRegards,Jay_Diddy_B
How to design a simple one-quadrant voltage follower with little dropout? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: September 18, 2019, 09:08:21 am
content: I have been designing a few debug adapters that samples target voltage for its own output buffers. However until now all designs powers the output side of the level converters using power from the target.I would like to avoid loading target power rail in my next designs, which means instead of powering the buffers directly I need a tracking regulator that uses target voltage only as a reference, while draw energy from the programmer’s own power source (usually USB.)For this tracking regulator, I need as little voltage drop as possible, especially for ones intended to work with a 5V target voltage (for example DAP405 high-speed CMSIS-DAP, which allows debugging of 5V microcontrollers.) What do I need beyond an RRIO op-amp? What topology do I need?The output buffers can be standard logic like 74LVC164245 or 74AVC4T774, or output banks on some PLD like XC2C32A or XC6SLX9.

author: dom0
author_rank: Super Contributor
timestamp: September 18, 2019, 11:34:14 am
content: Op amp voltage follower, possibly with an external NPN emitter follower, if you need more than typical op amps can supply (~5-10 mA for single supply, low voltage op amps).

author: technix
author_rank: Super Contributor
timestamp: September 18, 2019, 11:43:59 am
content: Quote from: dom0 on September 18, 2019, 11:34:14 amThere is still at least one diode drop for NPN emitter follower. Is there anything that can do next to no drop?

author: dom0
author_rank: Super Contributor
timestamp: September 18, 2019, 11:47:22 am
content: Put the NPN inside the op amps feedback loop.

author: Ian.M
author_rank: Super Contributor
timestamp: September 18, 2019, 12:24:59 pm
content: That still doesn't help if the OPAMP is running from the same supply as the collector of the emitter follower. You either need a boosted supply, or a topology similar to that used in a LDO regulator, e.g. a PNP pass transistor driven by an error amp, with the regulator's reference replaced by a fixed proportion of your target Vcc.Also, if you've got to support a 5V target, its not exceptional to encounter the case where your target Vcc is up to 10% high while USB Vbus is as low as 4.75V. That can result in target logic '1' level being over 0.7V higher than your devices, which is enough to cause issues for CMOS inputs that aren't over-voltage tolerant.I therefore suggest that you boost to say 6.5V to allow enough headroom for a simple OPAMP + emitter follower to regulate your buffer Vcc to match a target Vcc of up to 5.5V. If its only going to be powering a few buffers, there's probably no need to improve efficiency disabling the boost for target Vcc below 3.5V.
How to design a usb 2.0 type C receptacle - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: September 18, 2021, 04:46:38 pm
content: I have made a custom board , the chip on the board uses USB 2.0 to communicate to a computer and uses a type C connector. No power delivery needed just going to use the standard 4 USB pins, D-, D+, 5v, GND but just in a type C connectorI would like to know if i still need to connect all other pins (expempt those 4) to somewhere, Especially the CC and SBU pins. how about those extra data pins? Rx1,Tx1 and Rx2,Tx2? connect them to ground or just leave them floating?Is there an official recommendation in this situation>? So i can modify things for the next prototype

author: langwadt
author_rank: Super Contributor
timestamp: September 18, 2021, 05:50:59 pm
content: I believe all you have to do for a usb2.0 device is a 5.1K pulldown on each CC pin, there are usb-c connectors that don't have all the extra pins

author: drakejest
author_rank: Regular Contributor
timestamp: September 18, 2021, 06:02:53 pm
content: Quote from: langwadt on September 18, 2021, 05:50:59 pmAbout that, i have read that some cables might already come with them , wont it be a problem if i placed one on my board?

author: langwadt
author_rank: Super Contributor
timestamp: September 18, 2021, 06:42:07 pm
content: Quote from: drakejest on September 18, 2021, 06:02:53 pmI wouldn't expect resistors in the cable unless it a cable usb-c and at one end and micro-sub or similar at the other end

author: drakejest
author_rank: Regular Contributor
timestamp: September 18, 2021, 07:24:40 pm
content: Quote from: langwadt on September 18, 2021, 06:42:07 pmIf for instance that there will be 2 resistors, what might happen? 1 from the cable and 1 fom the board? because i can see that i might use a typa A to type C cable

author: langwadt
author_rank: Super Contributor
timestamp: September 18, 2021, 07:32:52 pm
content: Quote from: drakejest on September 18, 2021, 07:24:40 pmwouldn't do anything since the cc pins don't exist on the type A, so the are not used

author: Terry Bites
author_rank: Super Contributor
timestamp: September 19, 2021, 01:14:20 pm
content: Page 143 of the diktat:https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjSpv6UjovzAhUC0uAKHW8hBSkQFnoECAQQAQ&url=http%3A%2F%2Fsdpha2.ucsd.edu%2FLab_Equip_Manuals%2Fusb_20.pdf&usg=AOvVaw3BsmKK0t0Dn1uEDPHB8guw
How to design analog filter using FILTER WIZARD website - Page 1
Forum section: electronics / projects

author: manjunath
author_rank: Contributor
timestamp: September 21, 2014, 09:11:42 am
content: Hi all,I am trying to design Analog low pass and high pass filters using the site.http://www.analog.com/designtools/en/filterwizard/#/typehttp://www.analog.com/designtools/en/filterwizard/#/typeI did not get how to select DB value in Stopband and Filter response selection.Can anyone help me how to use this site.Thanks.

author: diyaudio
author_rank: Frequent Contributor
timestamp: September 21, 2014, 09:31:20 am
content: Quote from: manjunath on September 21, 2014, 09:11:42 amThere seems to be a bug when you change the value on the stopband value, anyways refresh the browser and you can changed the value. note as you increase the magnitude of the stop band so does the filter order the default is 2 stages (4-th order) at 40-db.
How to design the pulse generator correctly... - Page 1
Forum section: electronics / projects

author: Folnia
author_rank: Contributor
timestamp: September 26, 2024, 02:16:09 pm
content: Hi,I'm working on a pulse generator with 2N3904.I've gone through the AN-47 and I made one almost same ashttp://www.kerrywong.com/2013/05/18/avalanche-pulse-generator-build-using-2n3904/with only power supply changed.The BJT is 2N3904TFR manufactured by ONSEMI. I found 120V cannot work so I changed the voltage to around 134V then the pulse generated.Attached are the scheme and captured output.My questions:1) Is there any way to know calculate/simulate the minimal voltage to generated the pulse based on the spec of the BJT?2) How to calculate the theoretical pulse amplitude ? Can I use the E = 1/2 CV^2 and give an estimation of the power consumed on the 50ohm resistor?3) From the captured waveform I can see some oscillation. I used a 50ohm coaxial connected to the scope BNC directly and the BNC input resistant is 1Mohm, so there might be a negative reflection. But why there's also oscillation before the pulse?4) If the pulse amplitude is too large, is there a clever way to do an attenuation to match the 50ohm 5Vmax scope BNC connector?Thanks in advance!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 26, 2024, 02:59:07 pm
content: Simulate -- no, this mode of operation is rarely if ever modeled. (Possibly the Diodes avalanche parts have models, I forget.)Breakdown is always between Vces and Vcbo(br). This can be quite a bit higher than the datasheet minimums (a mere 40V!) but you don't really know how much more until actual testing.Adjusting the base resistor is a good way to find the sweet spot, both in terms of what Vce and Ic is needed for trigger, and over what range stable triggering will occur. I found 4.7k, and 100-120V supply, effective for the Fairchild 2N3904s I have on hand, but YMMV.Yes, a simple resistor attenuator affords any lower output amplitude.Tim

author: tggzzz
author_rank: Super Contributor
timestamp: September 26, 2024, 03:12:43 pm
content: Quote from: Folnia on September 26, 2024, 02:16:09 pm1) not that I know of, because avalanche operation is outside the specification and outside the standard Ebers-Moll model. There are a few (?Zetex?) transistors which do have avalanche specifications.2) No.3) This might be a measurement artefact, either due to lead lengths (1mm of wire is 1nH of inductance), or the interpolation functions inside your scope (use an analogue scope or RTFM).4) The pulse amplitude is poorly defined. A very narrow 1kV pulse could be "integrated" by a scope's bandwidth so that it appears the same as a 10V wider pulse. In addition, while "matching" and "attenuation" can go together, they are different.If a 250ps-300ps 2.5V step into 50ohms would suit your purposes, a 74LVC1G* generator would give more predictable results. FFI see the "show us your square wave thread".
How to detect a USB charging port? - Page 1
Forum section: electronics / projects

author: sebmadgwick
author_rank: Regular Contributor
timestamp: August 08, 2014, 04:08:49 pm
content: I understand thatthe USB spec describesa dedicated charging port (up to 1.5 A) as having a short between D+ and D- of no greater than 200R.I was considering detecting this by connecting two GPIOs to the existing D+/D- lines and having the uC run a brief routine enabling/disabling GPIO pull-ups/downs/tristate in such a way to detect this short. The GPIO would otherwise be configured HiZ to prevent interference.Is this a bad idea? I'm wondering if the one-off routine risks causing issues on a conventional port.

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: August 08, 2014, 04:52:52 pm
content: Here I have attached a PDF doc called "USB Battery charge spec 1.2". It has all the details ... I am sure it does ... I fell asleep on page 3Rest should be here:http://www.usb.org/developers/devclass_docs#approvedThey talk about detection somewhere on page 27 and up.

author: sebmadgwick
author_rank: Regular Contributor
timestamp: August 08, 2014, 05:10:18 pm
content: Thanks for the link. Document page 8 (pdf page 19) ofBC1.2_FINAL.pdfdescribes charger detection hardware and indicates the separate circuitry for detecting a DCP (Dedicated Charger Port; what I refereed to) and CDP (Charging Downstream Port).I was hoping for a simpler solution. For example, my suggestion above doesn't not require any extra hardware.

author: German_EE
author_rank: Super Contributor
timestamp: August 08, 2014, 06:47:39 pm
content: This is the first time I've come across an experiment where a variable electronic load would be useful (and I do not have one).1) Wire an ammeter and variable load across a USB port, increase the load and see what current you reach before it trips out2) Short together D+ and D- then repeat.Any volunteers to try this?

author: jakeypoo
author_rank: Regular Contributor
timestamp: August 08, 2014, 06:59:02 pm
content: There are some ICs that do the Dedicated charger detection.If you're doing battery charging check out the BQ24050 series. You could use that as an LDO as well, but maybe there are dedicated USB-powered LDOs out there.
How to detect actuator feedback voltage using Arduino/esp32? - Page 1
Forum section: electronics / projects

author: mrnams
author_rank: Newbie
timestamp: September 21, 2023, 02:39:46 pm
content: Hello,I am operating motorized ball valve using ESP32 and relay module, ball valve has two feedback voltage to detect close and open position of valve, there are two output wires one to detect close state and one to detect open state of valve. see below image.My question is how to collect feedback using Arduino/ESP32 to detect open/close state of valve ?Open state voltage between "R1(BLUE) and Negative(BLACK) will be 24v DCClose state voltage between "R2(YELLOW) and Negative(BLACK) will be 24v DC

author: jwet
author_rank: Frequent Contributor
timestamp: September 25, 2023, 03:46:04 am
content: The blue and yellow wires tell the state of valves except that they're 24v rather than the 3.3v you need. Connect a voltage divider to blue and yellow that is 100k on the top and a 10k on the bottom going to black. Take your output from the junction of the two R's to the ESP. This a 11 to 1 divider and will safely give you a logic high when there is 20-30v (24v nominal) on these lines. Before connecting ESP, use a voltmeter to verify that you don't have a wiring error and you get either 0v or >2.4v in the two valve states.
How to Detect CT Disconnection in a Leakage Current Measurement Circuit? - Page 1
Forum section: electronics / projects

author: kagoun
author_rank: Newbie
timestamp: July 22, 2025, 05:50:12 am
content: Hello everyone,I'm building a circuit to measure current. The main idea is to use a current transformer (CT) to step down the current and then measure it using three different op-amps with different gain levels, connected to the ADC channels of a microcontroller. The goal is to detect leakage current. So far, everything is working conceptually.However, I have a concern regarding a specific edge case. Since the purpose of this circuit is to measure leakage current, when there is no leakage, I expect the ADC readings to be close to zero. But if the CT wires are accidentally disconnected, I will also read zero from the ADC. My question is:How can I distinguish between these two scenarios (no leakage vs. disconnected CT)?Is it possible to detect this difference purely in software, based on what the ADC sees, without adding extra hardware to the circuit?I haven’t built the circuit in real hardware yet, so I’d like to analyze this aspect first before proceeding.Also, I have a sample project that seems to handle this. I’m attaching pictures of it below. In particular, I think the U1-P30 pin might be used for this purpose. The CT is connected between SP16 and SP12.

author: Slh
author_rank: Regular Contributor
timestamp: July 22, 2025, 07:00:31 am
content: Add a high value pull up resistor where the CT is connected. When the CT is connected the pull up will have no effect. When it's disconnected the ADC value will be near the limit.

author: kagoun
author_rank: Newbie
timestamp: July 22, 2025, 10:46:37 am
content: By 'ADC', do you mean I should connect the ADC input to the point where the pull-up resistor is and measure the voltage there?

author: Slh
author_rank: Regular Contributor
timestamp: July 24, 2025, 07:36:29 am
content: No, leave the ADC where it is and put the pull up at the input to the opamps.
How to detect USB version device plugged to – determinate max available current - Page 1
Forum section: electronics / projects

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 23, 2018, 11:26:32 pm
content: Hello,I'm making RGB LED keyboard (ATmega32u4 MCU) with changeable cable and would like to dynamically change LED MAX current according to available power. My goal is to set 800-850mA limit on USB3 and 400-450mA on USB2.According to this video (link below) USB3 type-C has "CC1" and "CC2" pins for orientation detection (they are pulled up), I assume all I have to do is to look for voltage on one of those pins. If 5V present – it's USB3, otherwise it's USB2:Any ideas, better way to detect?EDIT: I realize that this solution will only work with Type-C, not with USB3 Type-A, so still need a solution.USB3 type C pinouts:

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 24, 2018, 01:40:08 am
content: I don't think it can be made to work on type C, but on type A and B, check if the USB 3 ground is actually connected to ground.

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 24, 2018, 02:59:08 am
content: Quote from: blueskull on December 24, 2018, 01:29:02 amand watch the world burnI'm planing to sell them, so no specification raping.Other idea I have is to look for voltage/resistance on extra differential pairs on USB3, tho I have no idea if this will work (I'll try it soon).If I don't find hardware solution I have to look in to software...

author: 3dgeo
author_rank: Frequent Contributor
timestamp: December 24, 2018, 03:52:14 am
content: Quote from: blueskull on December 24, 2018, 03:23:06 amWell, I might add "let the world burn" option in my solution list for this issue, tho I have to do some testing first.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 24, 2018, 05:36:50 am
content: Quote from: blueskull on December 24, 2018, 01:45:49 amWere the standards designers really that stupid? I would have said something to the effect of that a device connected to a USB 3.0 port can use up to 900mA as long as it can determine it is in fact connected to a USB 3.0 port, and even suggest a simple circuit for that purpose.There's also USB CDP and DCP, as well as type C having a lower resistance pullup to signal high current and a digital protocol to change voltage.
How to detect when a PV controller is off ie at night - Page 1
Forum section: electronics / projects

author: towlerg
author_rank: Contributor
timestamp: July 14, 2018, 11:47:48 am
content: I thought disconnect from battery (with a relay) and measure output with potential divider and ADC of uC.To put this in context seehttps://www.eevblog.com/forum/projects/mesuring-a-12v-lead-acid-battery/?all
how to determine amount of load current to test internal resistance? - Page 1
Forum section: electronics / projects

author: jingpekto
author_rank: Newbie
timestamp: April 08, 2016, 11:54:12 am
content: hi Guys! i have this project to determine the internal resistance of the 12v deep cycle battery, i attached the datasheet.one of my problem is how to determine the effective amount of current to be drawn by the resistor load where i can already determine its internal resistance?currently i'm stating that the current to be drawn by the resistor load is 20A, so 12V/20a = 0.6 ohms, resistor rated power should be Power=(20A*20A)(0.6ohms) = 240W !! i think this is too big??i am thinking if am only putting the load for about 2 to 5 seconds to measure internal resistance, should i really need to get a 240W rated resistor load or do i only needsmaller wattage of resistor load because i'm only putting the resistor load for only 2 to 5 seconds...and is 20 amperes of load current correct to effectively determine the internal resistance?is there a minimum or maximum current to be drawn from the load if your determining the internal resistance of a 12v battery?hope you give some tips and advise guys! thanks in advance!!regards,pekto

author: Siwastaja
author_rank: Super Contributor
timestamp: April 08, 2016, 12:31:01 pm
content: DC resistance, especially for such a non-ideal battery as lead-acid, is not a constant, it's a function of (too) many parameters.The best you can get is to measure the DC resistance near the operating condition that is of interest to you. I.e., what are you going to do with the result?Usually, step test with two test currents, neither of which is zero, is used. For example, 10A and 50A. R = (U2-U1)/(I2-I1)Give it a few seconds to be meaningful for real-life seconds-long peaks.Temperature, state-of-charge and condition of the battery affect the resistance a lot. If you are just testing to analyze the condition, then keep state-of-charge and temperature constant.

author: Kilrah
author_rank: Unknown
timestamp: April 08, 2016, 12:38:07 pm
content: The averagecar battery testerwill draw about 100A on the battery during a few seconds and bring a big fat piece of wire to red hot in that time.
How to calculate battery life ? - Page 1
Forum section: electronics / projects

author: Swaroop 21
author_rank: Regular Contributor
timestamp: July 05, 2024, 11:38:58 am
content: How do I calculate the remaining backup time of a battery ?I have a home made ups for my routers in which I have used 2S 7500mAh Li-on pack, I am measuring the load current using a INA219. The circuit is boosting the 7.4V nominal to 12V using a boost converter. I have to display the remaining backup time. So I am confused how do I get it right, Unlike just displaying the battery percentage (10, 20%). I want to display the hours. The routers draw about 8W. I am currently doing it by just"int remainingTime_hours = batteryCapacity_Wh / power_W;"where batteryCapacity_Wh is 55.5Wh and the power_W varies depending on how many routers I have online. minimum is around 3W.I have a doubt that maybe I need to monitor the power going in the battery and also the power out of the battery. Or can I just do it with battery Voltage, Capacity and the load voltage, current (POWER).

author: jwet
author_rank: Frequent Contributor
timestamp: July 05, 2024, 01:24:24 pm
content: Your life calculation will only be correct when you initially go into backup mode. You need to decrement the battery capacity as the load draws on it. You could take the 55 WHr and deduct the estimated load power/60 once per minute to give a "fuel gauge" like reading. This is likely about 20% kind of accuracy- probably adequate for the application. Instead of just estimating the load, you could use the current and voltage and calculate the actual load power accurately. This will improve accuracy some but battery capacity is non linear and varies with load, temperature and battery history/cycles/age.If you want to dig in deeper, there is a lot of information on the subject. There is a formula called Peukert's law that is used in some battery fuel gauging systems to estimate the effective discharge rate of a given load. Its a non linear equation where I is raised to a fractional power to give an effective I. It was developed for Lead Acid chemistries but the physics should be similar. There is a good wiki. You still have temp and historyThe other source of some knowledge is app notes, patents and literature from chip makers like Maxim and TI describing their fuel gauge solutions. Maxim "Model Guage" could achieve something like 5% of true capacity in the real world for a phone or notebook over its life using a lot of tricks.

author: Swaroop 21
author_rank: Regular Contributor
timestamp: July 05, 2024, 02:24:11 pm
content: Indeed I am monitoring the load voltage and current using a INA219 as mentioned and also the battery voltage is monitored separately via a resistive divider which to the analog pin of ESP12F as the battery voltage is then boosted using a boost converter to 12V . I am not sure what to look for on the internet I looked up on youtube but all I could find was either the battery voltage be shown as percentage or battery capacity tester which I am not interested in. If there's any similar project where I can get the code snippet from please link it
How to determine LED Vf and If (from Monitor Backlight) - Page 1
Forum section: electronics / projects

author: kolbep
author_rank: Frequent Contributor
timestamp: February 08, 2022, 05:05:58 pm
content: Hi All,I have pulled a LED Backlight strip out of a dead laptop.The LED Strip is approx 3mm to 4mm wide, and has 10 Parallel Sets of 3 Leds in series.I would like to use the strip in another Industrial HMI that has CCFL's that have failed,(The HMI has 24vdc available, so I will be stepping that down).however as the Laptop was not working, I was unable to measure the Voltage and Current for the LED Strips.As a test, I slowly ran the set up in voltage. It barely lit at just over 3 volts. 8v gave a decent light, but without current limiting, I did not want to risk taking the strip more than that.What is an easy way to determine the maximum Vf and probably more importantly the If of the strip, As I would like to run them brighter, but do not want to risk it. My plan is to get a CC / CV module, and then hook it up to the backlight.There is no markings on the Strip or LED'sP

author: ledtester
author_rank: Super Contributor
timestamp: February 08, 2022, 06:56:09 pm
content: You can put a resistor in series with the LED strip to prevent sending too much current through it.For instance, a 1K resistor will allow at most 24 mA from a 24V power supply. I'd use a 1W resistor -- or four 1/4W resistors in parallel.Once you have 5 to 10mA going through the LED strip you'll get a good idea of what the Vf is.

author: bob91343
author_rank: Super Contributor
timestamp: February 08, 2022, 07:22:38 pm
content: Typically a single LED will draw 20 mA.

author: wraper
author_rank: Unknown
timestamp: February 08, 2022, 07:41:17 pm
content: Quote from: bob91343 on February 08, 2022, 07:22:38 pmLED will draw as much current as you push through it regardless of its ratings (until magic smoke escapes). LEDs used for backlight and illumination usually are rated for way more than 20mA.

author: TimFox
author_rank: Super Contributor
timestamp: February 08, 2022, 07:51:32 pm
content: As with other forward-biased diodes, the voltageVfacross an LED is roughly proportional to the logarithm of the current, and decreases with increasing junction temperature at constant current.Driving such a device from a constantvoltageis therefore dangerous, since the current willincreaseat a constant voltage as the junction temperature increases, possibly leading to catastrophic failure.
how to determine maximum Vref frequency for DACs? (multiplying dac) - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: March 08, 2014, 04:36:18 am
content: So I want to use a DAC as a Multiplying DAC.Essentially I want to figure out what is the maximum frequency the Vref can be before the DAC output becomes distorted (using it as a multiplier or attenuator).I understand that MDACs are designed for this, but is there a trick to finding out what the maximum frequency is for any dac so that you are not confined to what is advertized as a MDAC? (multiplying DAC).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 08, 2014, 11:02:46 am
content: Should be specified in the datasheet.Usually, they drop off around 200kHz, but beware the error and the cutoff frequency usually vary with code...Tim
How to determine the phase boost for a type 2 compensation circuit?  - Page 1
Forum section: electronics / projects

author: Patrick66
author_rank: Regular Contributor
timestamp: May 04, 2024, 10:47:41 am
content: Hello, the figure below where the orange color line is the compensator frequency response, blue color line is the plant response and the yellow line is the final open loop response for the system. May I how to determine the phase boost of the compensator at cross over frequency? Is is 90-25.7 degree which is 64.3 degree phase boost? Thank you in advance.
How to determine the physical size of SMD capacitor. - Page 1
Forum section: electronics / projects

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: December 13, 2024, 06:41:22 am
content: I need smd 3.3nF charging 48v with 1.25A pulse. Should I use small size 0608 or big size, 1206 more dissipation?

author: Andree Henkel
author_rank: Regular Contributor
timestamp: December 13, 2024, 02:10:12 pm
content: I=C*dU/dt; I=1,25A; C=3,3nVgives Voltage Slope 379V/µs across the capAre you sure?H´m current ratings are not typically to be found in datasheets for chipceramic caps of lower nF Valueso good luckyou may need some caps of smaller value in parallel of smaller size, probably preferable to one largerreverse geometrie is probably preferable for lower ESL and ESR, as you enter RF territory regarding Voltage Slopeeven better suitable could be X2Y type like:https://www.digikey.de/de/products/filter/keramikkondensatoren/60?s=N4IgjCBcpgnAHLKoDGUBmBDANgZwKYA0IA9lANogAMIAugL7EC0AzMiGpAC4BOArkVIVwNBswjQOGHAWJlIlAOxUkxRWABMdRiCYAWdpyx5B8ygFYWsRSGIa9ih9vr0gAthere are comparisons in decoupling applications comparing standard, reverse geometriy and X2Y type.bottom line for suitable decoupling of like a FPGA power rail x2y can do it with fewest caps and area, standard needs most caps and area and reversed geometry is in between.what do you actually want to achieve? Decoupling or what?

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: December 13, 2024, 07:07:42 pm
content: It is a 2.2uH inductor that gets charged with 2.5A by a pair of 3.3nF on vcc and ground. The fly wheel current in the inductor is maintained by a pair of diodes.The frequency is 300khz.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 16, 2024, 05:26:06 pm
content: The limiting factor will probably be the current handling of the interconnect.Dielectric dissipation could be as high as 1-2% for high K capacitors.
How to determine the time to acheive steady state in LED driver  - Page 1
Forum section: electronics / projects

author: Patrick66
author_rank: Regular Contributor
timestamp: March 30, 2024, 10:43:26 am
content: Hello everyone I'm currently building a flyback converter or LED driver that is operating in DCM mode and I wanted to study the difference in the time to reach steady state of 0.7A when the input increases by 20% at 70ms with different types of compensators. The figure below shows the output voltage and current waveform when 20% input voltage is introduced to the circuit at 70ms. Wanted to ask how to determine the time required to achieve steady state for the system. Thank you everyone for your time and help.
How to do AC response of SMPS in Micro-Cap 12.  - Page 1
Forum section: electronics / projects

author: MacIntoshCZ
author_rank: Regular Contributor
timestamp: March 02, 2023, 07:37:52 pm
content: I just simulated uncompensated PSU in micro-cap 12 and i would like to do AC- response but i dont know how. I am getting this error "Failed to converge during AC analysis Function source iterations."I am attaching circuitry, thanks for help.

author: jonpaul
author_rank: Super Contributor
timestamp: March 03, 2023, 02:27:45 am
content: Post only images, not ZIP or files that need downloads, as,most use tablets,or mobiles.First check schematic and nets for errors.See microcap 12 help.Jon

author: MacIntoshCZ
author_rank: Regular Contributor
timestamp: March 03, 2023, 06:43:11 am
content: I am not familiar with those settings. I would like to set V3 AC source to sweep from 10Hz to 100k ( there is 10Meg in dialog that should be changed).

author: Terry Bites
author_rank: Super Contributor
timestamp: March 03, 2023, 12:38:34 pm
content: Change the X expression to "frequency;V3"

author: MacIntoshCZ
author_rank: Regular Contributor
timestamp: March 03, 2023, 06:30:22 pm
content: frequency;V3 has same effect as only "F", but i figure out that i need to use "voltage source" instead of "sine source" and also i need to disable calculating operating point, else orror ocurs. Now i have plot but i guess its not what i seek. Gain is too low.I think maybe it does sweep before plant is stabilized. Does anyone know how where i can setup delay before it starts ac analysis? Thanks
how to drive a IV-8 VFD tube from a 12V supply - Page 1
Forum section: electronics / projects

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: November 26, 2013, 09:17:02 am
content: hello, i have run into a small problem with one of my projects.i would like to run 8 IV-8 VFD tubes from a 12V DC supply and be able to control them from a 5V micro. unfortunatly i was unable to find a translated version of the IV-8 datasheet so i gave it a go myself but some of it may be wrongi spent a good hour translating it (i don't speak or read Russian at all so I don't know if it is fully correctbut i gave it a go and its the PDF attached. if any one can read Russian i can upload the original datasheet if you want.Am i correct in saying that the anode and grid need to be AC voltage at 50V if i am directly driving it? and how do i control a VFD display as i ws told they act as triodes but i am still looking into triodes and how they work.any help on this would be great

author: Fagear
author_rank: Regular Contributor
timestamp: November 26, 2013, 10:05:49 am
content: I can read Russian.There is one scheme,take a look. Russian language, but schematics are international.Seems like translated datasheet is pretty close to original. Except:"Anode current, total segments, mA" must be "0.8 - 2.5""Grid current, mA" must be "3 - 5"

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: November 26, 2013, 10:22:31 am
content: so it isi was close, i just didnt read the datasheet i had properly i thought it was missing the +- part as it just says 0.8(in superscript)+1.7 for anode current and 3(in superscript)+2il have a look at that website now (thank you chrome for auto translation ^.^also from what i can tell from that schematic are they driving the tubes from a rectified 50V sine wave?

author: dannyf
author_rank: Super Contributor
timestamp: November 26, 2013, 12:26:24 pm
content: QuoteThat should always be the first thing you do.

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: November 26, 2013, 10:38:07 pm
content: Quote from: dannyf on November 26, 2013, 12:26:24 pmIf you read te rest of the sentence i did say that i ddnt read the datasheet properly, i was converting it from a language i did not know or have any relation too that language so i did not read te datasheet properly when translating it.

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: November 28, 2013, 08:52:25 am
content: From that design on the russian website it looks like it is using pulsed DC. Would i be able to use a boost converter to get from 12v to 50v and then pulse the output of that to get the power supply for the VFD's?
How to drive atx switching transformers? - Page 1
Forum section: electronics / projects

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: August 06, 2015, 09:27:44 am
content: Hi everyone one!Has anyone know or got a schematic or link with some information on how to drive these.My aim to to use these to convert low voltages to higher voltages. I have tried to run one on a ZVS driver and it didn't work.Thanks

author: Isad
author_rank: Frequent Contributor
timestamp: August 06, 2015, 12:15:51 pm
content: Quote from: rickselectricalprojects on August 06, 2015, 09:27:44 amHow did it not work on a zvs that works usally all the time u must have doen somthing wrong.

author: amyk
author_rank: Super Contributor
timestamp: August 06, 2015, 02:18:42 pm
content: Plenty of schematics here...http://danyk.cz/s_atx_en.html

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: August 07, 2015, 05:49:33 am
content: Quote from: Isad on August 06, 2015, 12:15:51 pmMaybe i didn't use the correct pins? What pins did you use?Thanks

author: Isad
author_rank: Frequent Contributor
timestamp: August 07, 2015, 10:33:39 am
content: Quote from: rickselectricalprojects on August 07, 2015, 05:49:33 am
How to drive multiple LEDs in turn with constant current? - Page 1
Forum section: electronics / projects

author: Folnia
author_rank: Contributor
timestamp: October 26, 2024, 01:19:45 pm
content: Hi，I'm looking for a solution for driving multiple LEDs (16pcs) in turn with adjustable constant current.Currently I'm using a constant current LED driver (current adjustable by PWM) with a 3-8 MUX, as shown the sch attached.The problem is ,the absolute current limit for per Channel of the MUX is ±20mA. So the LED current is limited pretty low.Is there any other clever solution - save the control I/O pins with large current capability?Thanks in advance!

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 26, 2024, 01:41:11 pm
content: You could use ULN2003 or similar with the common emitter going to the constant current sink.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 26, 2024, 01:50:00 pm
content: There are a gazillion different LED drivers out there, from the very cheap PT4115 (cheap enough to one for each channel) to drivers which can control 50 LEDs or more.

author: MasterT
author_rank: Frequent Contributor
timestamp: October 26, 2024, 01:51:28 pm
content: TPIC6B595TPIC6B596TPIC6C595TPIC6C596

author: Folnia
author_rank: Contributor
timestamp: October 26, 2024, 02:11:43 pm
content: Quote from: NiHaoMike on October 26, 2024, 01:41:11 pmYes I think it might be the most robust way to make it. But need to add a 3-8 encoder to control the ULN2803. Thanks!

author: Folnia
author_rank: Contributor
timestamp: October 26, 2024, 02:19:52 pm
content: Quote from: MasterT on October 26, 2024, 01:51:28 pmThat's quite a compact part, it will meet my request very well if there's a high side version .
How to drive NFET with current sink (LP5569)? - Page 1
Forum section: electronics / projects

author: tipo1000
author_rank: Newbie
timestamp: April 02, 2019, 07:02:07 am
content: I have a circuit (pic attached) where LP55231 is driving NFET and the load is a LED. It's working fine.Now I need to switch LP55231 to LP5569. The difference is that LP55231 PWM output is current source and LP5569 PWM output is current sink. (LP55231 and LP5569 functional block diagrams attached.)How do I need to change the circuit to get it work with LP5569?I tried to figure it out with LTspice, but couldn't get it to work.Thanks,Tipo

author: Wimberleytech
author_rank: Super Contributor
timestamp: April 02, 2019, 02:48:18 pm
content: Just use a complementary version.
How to drive this aircraft servo motor? - Page 1
Forum section: electronics / projects

author: georges shed
author_rank: Contributor
timestamp: July 10, 2020, 02:57:54 pm
content: Hi all,I have this collins servo motor out of a radio altimeter, and ideas how it works/ how i can drive it? It seems to have 3 coils, reference and 2 control.Thanks!

author: Renate
author_rank: Super Contributor
timestamp: July 10, 2020, 07:04:54 pm
content: Yeah, it's a selsyn or synchro, for aircraft usually 400 Hz.It was designed to have the two control windings being feed from a similar device.The two devices would be powered by a reference 400 Hz supply.If you want to make it spin around without another unit you would have to generate 2 sin/cos control phases and one reference phaseor two quadrature control phases and one variable reference phase.

author: capt bullshot
author_rank: Super Contributor
timestamp: July 10, 2020, 08:03:27 pm
content: Yes, it's kind of a resolver.There's some explanation on wikipedia and other websites:https://en.wikipedia.org/wiki/Resolver_(electrical)https://www.dynapar.com/technology/encoder_basics/resolvers/Most explanations you'll find will deal with them as position encoders, outputting electrical signals. Your device just works the other way 'round, you supply the electrical signals and the shaft rotates accordingly.More commonly used for this purpose are synchros, most probably you'll find better examples of how to use them as actuators when googling for "Synchro".Resolvers are 90° shifted two phase, while Synchros are 120° shifted three-phase. Otherwise they work the same way.

author: madires
author_rank: Super Contributor
timestamp: July 10, 2020, 08:33:46 pm
content: Synchro/Resolver Conversion Handbook - DDC:https://www.ddc-web.com/documents/synhdbk.pdfSynchro and Resolver Engineering Handbook - Moog, Inc.:https://www.moog.com/literature/MCG/synchrohbook.pdf

author: Renate
author_rank: Super Contributor
timestamp: July 11, 2020, 12:02:30 am
content: Hey, nobody mentioned the Analog Devices book:https://www.analog.com/en/education/education-library/synchro-resolver-conversion.htmlThe DDC handbook looks comprehensive, but they are unfair to absolute encoders for "monotonicity" (pg 3).I guess that they never heard of Gray code.

author: georges shed
author_rank: Contributor
timestamp: July 13, 2020, 09:15:55 am
content: Thanks you all for the reply’s! I’ll look at those links and get stuck in!
How to effectively control duty cycle in this motor control application? - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: October 08, 2018, 06:13:35 pm
content: I'm controlling a DC motor via PWM @10 kHz. Nameplate of the motor attached. I'm increasing the duty cycle in steps of 8%. Every step means a high current for a brief moment (for that motor). My question is: Do these steps changes represent a potential problem? Should I lower the step change? Or how can I vary duty cycle smoothly? I'm doing this with a microcontroller, so it's something more software oriented.

author: H.O
author_rank: Frequent Contributor
timestamp: October 08, 2018, 07:17:09 pm
content: QuoteFor the motor? I would say no, as long as the peak current is below the demagnetisation for the motor - which for that motor likely is a few hundred Amps.For the load it's driving? Possibly but that's up to you to judge.For the drive circuit? Possibly but it depends on the magnitude and duration of the current pulse and on the design of the drive circuit of course.What you're seeing is basically what you'd see if you just slapped the motor across a voltage 8% of the total supply voltage (or 8% higher than the current supply voltage). At first all that the supply sees is the resistance of wiring, the brushes and internal resistance of the armature. The current will quickly (but not instantly due to the inductance) rise to U/R and then, as the speed of the motor increases the current will drop until BEMF=U. If you want to limit the current peak then ramp up the voltage (dutycycle) in smaller steps.

author: Benta
author_rank: Super Contributor
timestamp: October 08, 2018, 07:33:47 pm
content: The motor doesn't care. A full DOL start pulls much more current. Your power switches might not like it, though.BTW, 10 kHz is probably a bit high for this kind of motor (magnetic losses), I'd suggest 2...3 kHz.* DOL = direct on line = 125 V bang on switching.
How to eliminate acoustic noise in high current circuits? - Page 1
Forum section: electronics / projects

author: MikeLemon
author_rank: Contributor
timestamp: September 24, 2018, 04:57:23 pm
content: Hello there,In every circuit I build with a simple switching mosfet at 10KHZ+ with 5A+ (to around 40A) I get audio able noises even tough I don't use any inductive components like inductors and such.Any hint on how to eliminate such noises?Thanks for helping.

author: hlavac
author_rank: Frequent Contributor
timestamp: September 24, 2018, 05:03:56 pm
content: Ceramic caps making the noise?Easiest fix may be to move up the switching frequency above 25kHz...

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 24, 2018, 05:31:29 pm
content: Yes ceramic caps can be pretty noisy especially SMD ones, transmitting vibration to the PCB they are soldered on.A few pointers:https://www.edn.com/design/components-and-packaging/4364020/Reduce-acoustic-noise-from-capacitorsNow if you don't use any ceramic cap in the power section we'll have to look elsewhere obviously.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: September 24, 2018, 05:40:01 pm
content: Could also be board layout, the traces are inductors and the PCB is a sounding board?Potting could reduce the noise.

author: SeanB
author_rank: Super Contributor
timestamp: September 24, 2018, 06:51:37 pm
content: Traces near a steel chassis, where you get nice magnetic forces turning the chassis into a speaker.

author: ejeffrey
author_rank: Super Contributor
timestamp: September 24, 2018, 08:04:29 pm
content: Also remember that your circuit includes the part *before* the switch too. If you have inductors or capacitors on the input/supply side they can make noise just as well as the load side.