hybridfree/eevblog-posts huggingface dataset:
Driving an INS128 amplifier.  - Page 1
Forum section: electronics / projects

author: mb
author_rank: Newbie
timestamp: June 04, 2016, 12:35:16 am
content: I have a question on the correct way to drive an instrument amplifier. I have an INS128 which I want to use to measure the voltage drop of a current shunt resistor. I'm not sure if I have to drive the instrument amps inputs through a couple of low impedance loads like a couple of unity gain buffers or can I connect the ins amp directly across the resistor I want to measure? Any help appreciated. Any pros, and cons on either method?Martin.

author: seriouscoinage
author_rank: Contributor
timestamp: June 04, 2016, 12:43:00 am
content: Instrumentation amplifiers are designed so they have high input impedance - there is no need for unity gain buffers. As long as the voltages you are connecting to the instrumentation amplifier are within the input voltage range of the amplifier, you can connect the current shunt directly.

author: mb
author_rank: Newbie
timestamp: June 04, 2016, 01:28:12 am
content: seriouscoinage, apart from wasting amps, what are if any considerations if buffers were used in front of the ins amp, just for the sake of discussion.

author: danadak
author_rank: Super Contributor
timestamp: June 04, 2016, 01:52:43 am
content: Is INS128 a typo, should it be INA128 ?If so that part has 10^10Zin.....Regards, Dana.

author: mb
author_rank: Newbie
timestamp: June 04, 2016, 04:09:30 am
content: its a typo INA128 is correct

author: wraper
author_rank: Unknown
timestamp: June 04, 2016, 06:38:35 am
content: Quote from: mb on June 04, 2016, 01:28:12 amReduced performance, of the most noticeable - offset and offset temperature drift would be introduced.
Driving an SFP Module with LVDS - Page 1
Forum section: electronics / projects

author: jamfletch
author_rank: Contributor
timestamp: July 30, 2025, 12:29:09 pm
content: Hi,I have an application where I'm using an FPGA to drive an optical SFP module, more precisely, this SFP module :https://docs.broadcom.com/doc/pub-005160. On the other end of the optical link, I have a CPLD that I'm communicating with, the receiving end is using the same optical SFP.I am using the FPGA's LVDS IO function to drive the SFP's differential TX inputs. I have CPLD code running that toggles an LED when I have succesful comms from the FPGA to the CPLD - thisworks, but it seems the reverse direction (i.e CPLD back to FPGA) doesn't work - I get garbled data.Now this could be an issue with the VHDL on the FPGA - due to some sort of synchronisation issue or whatever. But I need to rule the hardware out first.The only difference on the CPLD -> Optical SFP route transmitting back is that the differential voltage levels driving the SFP are just within the spec given by the linked datasheet. The FPGA module is driving the SFP with about 500mV diff, the CPLD with about 400mV. I can see though that data is going back into the FPGA from the CPLD on it's receive differential pairs by probing it with an oscilloscope, so I can conclude that at least the CPLD is driving the SFP module sufficiently to trigger the optical drivers.Is there any reason why having lower voltage levels would cause TX issues here? I feel that as long as the differential voltage is enough to trigger the optical SFP, and I can confirm that I'm seeing a differential voltage on the other end of the link, that I have sufficient voltage drive?
driving bipolar stepper with only 3 leads - Page 1
Forum section: electronics / projects

author: newmaster
author_rank: Contributor
timestamp: January 05, 2019, 10:10:10 pm
content: I have this problem I can´t figure out myself:I have a dead 4 axis CNC controller, that I can/t repair. instead, I started to think about buliding a new controller. it only needs to move 3 axis table to the right spot and then all the work will be done with rotating axis from there. the controls can be extremely simple. even if I have to manually enter coordinates for each axis, it will be fine. drive speed is not important, exept for the rotating axis.anyways, the system is built so, that they have a regular 4 wire motors, but 2 poles are connected together in the housing covering the motors, making it 3 wire drive. wiring is burried inside the machine and raplacing it would be extremely difficult. also, only one motor is reasonably well accessible.are there any off the counter stepper drivers available that can control the motors with 2 poles tied together, through 3 wires?I tried to search, but my technical english vocabulary might not be good enough. I didńt find anything useful.also, can anyone explain, what could be behind this kind of design decision? are there any benefits to it?

author: ajb
author_rank: Super Contributor
timestamp: January 05, 2019, 10:52:20 pm
content: Are you sure the steppers are 4-wire? Three-phase steppers are a thing, and there are off-the-shelf drivers for them, though they're not as common as four-wire systems. If the motors really are four-wire with two wires connected together, then you would need a bipolar power supply to drive them. Normal four-wire drivers rely on full-bridge outputs to be able to drive current in both directions through the coil, but if the motor coils are tied together then the simplest solution is to connect the coil common to ground and use a pair of half bridges with positive and negative supplies to drive each coil in either direction. If the CNC system is old, then maybe the cost in terms of silicon was enough of a reason to design it this way.

author: richard.cs
author_rank: Super Contributor
timestamp: January 06, 2019, 11:32:35 am
content: Measuring the resistance between all three pairs will tell you if they are three phase (all similar resistance) or 2 phase with a common wire (two similar, one double).

author: newmaster
author_rank: Contributor
timestamp: January 06, 2019, 12:28:07 pm
content: they are definetly bipolar motors with 4 wires. I opened up the rotating axis motor connection box to verify. unfortunately, other motors are hard to access, so rewiring them is almost impossible without disassembling the linear table.
driving compatability between DS1110S and 74ABT04 - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: July 29, 2024, 07:26:58 pm
content: Hello , I am connecting 0-3.3V pulse as an input to DS1110S.pullup current is 1mA pull down is 12mA also it was said that it could drive 10 74LS type loads as shown below.because the pull up current is drastickly lower i think we need to use pull up resistor.my load is 74ABT04 whi input capactiance is 3pF.1.what is the capcitance of typical 74LS device?2.I was tol that if i connect 74ABT04 to the output of DS1110S the i dont need pullup resistor between them.Why is that? I know we have a formula I=CdV/dt.How can we know that we dont need pullup resistor?Thanks.https://www.analog.com/media/en/technical-documentation/data-sheets/DS1110.pdfhttps://assets.nexperia.com/documents/data-sheet/74ABT04.pdf
Driving high power LEDs - Page 1
Forum section: electronics / projects

author: somlioy
author_rank: Regular Contributor
timestamp: December 14, 2017, 06:01:29 pm
content: HiGot a lamp with 9pc 50W LEDs with Vf ~ 34V and If ~ 1.5A each. The nine COBs are mounted on aluminium-angles, submerged in circulating oil.The whole unit is then to be submerged in seawater.What I'm courious about is how should the leds be driven aswell as how should it be configured. I need to be able to dim the LEDs.The controller(s) is to be placed above the sea in a separate cabinet.

author: danadak
author_rank: Super Contributor
timestamp: December 15, 2017, 12:46:33 am
content: Principally drive with a constant current source.Google "led drive application note", tons of help and references.Regards, Dana.

author: mariush
author_rank: Super Contributor
timestamp: December 15, 2017, 01:16:19 am
content: You could simply use a LED DRIVER with ability to control the brightness through a PWM pin or by setting a resistor.Note that if the led is at quite a long distance away from the control box, you should account for the wire resistance as well ( the circuit would most likely use a low value resistor like 0.1 ohm for example to measure the current ... so if you use a few meters of AWG18 wires with 21 mOhm per meter of resistance, that can affect the 0.1 ohm value) .If you want to be really accurate you could have the current sense resistor near the led and then you could use a couple of thinner wires or just one thinner wire to bring the actual voltage measured to the control IC.Check out for example Richtek RT8463GQW :https://www.digikey.com/product-detail/en/richtek-usa-inc/RT8463GQW/RT8463GQWCT-ND/6205469It can work with up to 50v and can operate in either buck mode (step-down) or boost mode (step-up) so for example you could design your circuit to either use a 12v..24v power supply and boost the voltage to ~34v (go as high as needed to get 1.5A through the led) , or you could for example use a 48v power supply and take that down to the voltage the led requires.The current is controlled through a current sense resistor, a 100mV drop sets the maximum current allowed through the leds.See page 6 of the datasheet for example circuits using analogue ( 0.2v to 1.2v range for 0..100% brightness) or pwm dimmingAnother chip worth looking up (but more expensive and boost only) would be LT3952 :https://www.digikey.com/product-detail/en/linear-technology/LT3952EFE-PBF/LT3952EFE-PBF-ND/5253630

author: somlioy
author_rank: Regular Contributor
timestamp: March 04, 2018, 01:48:10 pm
content: Sort of forgot about this...Cable down to the light will be 3 cores (2+earth) at either 1.5mm^2 or 2.5mm^2 with a length of probably around 20-30 meters.So I either has to choose between high voltage or high current, or possible something in between?

author: ocset
author_rank: Super Contributor
timestamp: March 04, 2018, 02:52:13 pm
content: What driving source do you have, or rather, would you choose to have?Is it mains 240VAC, or some DC level.Please Tell us this , and then we can give good recomendation.
Driving lots of motors for kinetic art - Page 1
Forum section: electronics / projects

author: donotdespisethesnake
author_rank: Super Contributor
timestamp: June 23, 2019, 04:05:40 pm
content: A question that pops up now and then is how to create an installation containing lots of motors, which can be coordinated to create an artistic display, aka kinetic art. A typical example :I have seen several questions on the subject, but no examples that demonstrate a solution. The engineer in me asks "what is the most cost effective solution?" and "How can we make a solution available to artists without much training in motor control?"For the sake of discussion, the BMW installation can be used. For this case, I would probably use multiple stepper motors, with a home switch. The question then is whether to use one big controller with loads of IOs, with all the motor drivers operating as slaves, or a more distributed system where the main controller communicates over a network and slaved controllers control a small cluster of motors.Ultimately I would like to create PCBs for controller and slaves, which could be used as modular building blocks for an installation.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 23, 2019, 04:41:42 pm
content: RC winch servos come to mindeasy to power and controlhttps://www.ebay.ca/itm/GRC-25T-Servo-Winch-Drum-RC-Rock-Crawler-Steering-Gear-Winch-Upgrade-Accessories/254255419000?hash=item3b32cdce78:g:dpwAAOSwlQhdCzwy

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 23, 2019, 04:44:51 pm
content: The BMW installation uses a custom winch with a stepper motor. It is extremely quiet.Winch servos are probably the easiest option, but a lot noisier.

author: DaJMasta
author_rank: Super Contributor
timestamp: June 23, 2019, 05:07:09 pm
content: My assumption would be prebuilt controller modules with serial interface so you can have many of them on a single bus without too many IOs, akin to addressable RGB LEDs. This seems to be about how most large scale options for artists are presented, and I think for people who aren't that electronics inclined, it's one of the simpler ones to conceive since you can have a single fairly standard controller manage everything, and you can still get dozens of updates a second on a long string because of the comparatively high serial bus speed for the small data packets. There's a lot of availability of various modules that can suit these needs and interface together with largely prewritten code and standard cables.I think the ones that are setup as reacting to sensor are more likely to be fully distributed, or which are connected to a more complicated single sensor (like a camera) and use a single board computer to do the required processing and mapping and then serially controlled motor drivers.
Driving MOSFETS with open drain output of Comparators. - Page 1
Forum section: electronics / projects

author: Arsh ahmad
author_rank: Regular Contributor
timestamp: June 29, 2022, 09:24:32 am
content: Is it possible to drive a MOSFET using a comparator having an Open-drain output?

author: Zero999
author_rank: Super Contributor
timestamp: June 29, 2022, 09:41:52 am
content: Yes, very slowly. Add a pull-up resistor. Again note, it'll be slow so no good for PWM.

author: Arsh ahmad
author_rank: Regular Contributor
timestamp: June 29, 2022, 09:57:24 am
content: I don't want to use it for PWN I only want to turn it on or off with an input signal.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 29, 2022, 09:59:45 am
content: With a small MOSFET (small Qg) and no concern about power dissipation and hence suitably low value pullup, such as 1kOhm, it isn't even that slow.

author: Arsh ahmad
author_rank: Regular Contributor
timestamp: June 29, 2022, 10:02:27 am
content: Yes, I think this might work.

author: Peabody
author_rank: Super Contributor
timestamp: June 29, 2022, 03:34:44 pm
content: Yes you can. I've used the INT/SQW alarm output of a DS3231 RTC, which is open drain, to turn on a P-channel mosfet. But you do need the pullup resistor so the gate never floats. I used 100K, but this was just a low-current power switch, so there were no real thermal considerations. I guess in theory it could also work with an N-channel mosfet. I feel less comfortable about that, but haven't really thought it through.They do make comparators with push/pull outputs, which would eliminate the need for the resistor, but I don't think they are common.

author: Arsh ahmad
author_rank: Regular Contributor
timestamp: June 30, 2022, 05:18:35 am
content: Thanks for the replies, I made a hardware prototype and it is able to drive both n channel as well as p channel MOSFETs.

author: Peabody
author_rank: Super Contributor
timestamp: June 30, 2022, 02:30:46 pm
content: With an N-channel mosfet, the mosfet will be turned on by the pullup resistor when the comparator output is off, so the mosfet is on by default. That also means the mosfet will be turned on when the comparator is powered down, which might not be what you want. With a P-channel mosfet, the mosfet is off by default, and only turns on when the comparator output is low. That would be considered the safer option in most cases.

author: Zero999
author_rank: Super Contributor
timestamp: June 30, 2022, 03:15:40 pm
content: Quote from: Peabody on June 30, 2022, 02:30:46 pmThat depends on whether the pull-up is connected to the same power supply as the comparator or not. The comparator might also behave in an unpredictable manner, during power cycles, especially if the ramp up/down is slow.
Driving motor from Battery or LDO? - Page 1
Forum section: electronics / projects

author: rgujju
author_rank: Newbie
timestamp: May 29, 2021, 11:45:14 am
content: Hello everyone!I am designing a smart watch and wanted to understand how to drive the motor.Should I drive the vibration motor directly from battery or from the output of the LDO?What would be the advantages and drawbacks of the choice?What difference would one make over the other?The other circuit requires about 60mA and the motor would require about 70-100mA.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 29, 2021, 12:07:17 pm
content: Does the motor run on steady DCor does it need some kind of drive waveform?

author: SeanB
author_rank: Super Contributor
timestamp: May 29, 2021, 12:42:00 pm
content: Run from the battery, with a LC filter on the motor supply, and extra filtering after your switch, which should include at least a transient suppression diode across the motor, along with some small ceramic chip capacitors close physically to the motor. Ceramic capacitor across the motor is not too critical, anything from 10-100n chip ceramic, and the LC filter as well is not too critical, just the coil must be well damped or a lossy ferrite bead type, so as not to make it a LC oscillator. Filter capacitor likely will be a high value chip ceramic type, so make sure to have some damping across the inductor to prevent making a high voltage spike that will damage the rest.99% of small vibratory motors are brushed, and are electrically noisy, but also tolerant of wide supply voltage swings, so unregulated well decoupled supply is fine.

author: rgujju
author_rank: Newbie
timestamp: May 29, 2021, 12:54:20 pm
content: QuoteIt works on DC. Its a ERM motor.QuoteMy concern about running from a battery is would the amplitude of vibration change due to drop in battery voltage from 4.2V to about 3.6V?

author: SeanB
author_rank: Super Contributor
timestamp: May 29, 2021, 01:46:34 pm
content: Not going to change much, the vibration amplitude depends on the rotating eccentric mass, and does not change much with voltage, though the frequency will change with voltage, but for a vibrator you really do not care if it is 15H or 18Hz vibration, just that it vibrated for the brief periods you need it to.
Driving old MOS chips: 6550 and 6540 : Current? - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: March 18, 2020, 10:38:40 am
content: I'm planning to build myself a small tester for 6540 MOS ROM and 6550 MOS RAM chips to diagnose a sick Pet 2001 which I recently purchased.To this end I am building up a small board based on ATSAMC20G15A-AUT for which I have a few samples in my parts bin. The I/O on a SAMC20G can sink 5mA and source 3mA.What are the actual requirements for driving these chips? 3mA will be plenty?I'm also thinking about putting current limiting R on all pins to the ZIF socket... How do I calculate those values? Just limit to 3mA?Thanks in advancePSPower and GND will be supplied separately

author: greenpossum
author_rank: Frequent Contributor
timestamp: March 18, 2020, 11:01:24 am
content: MOS gates are high impedance and current draw is negligible. You should be more concerned about the logic levels, whether the driver can provide adequate logic voltages, especially if you interfacing from BJT logic.

author: tggzzz
author_rank: Super Contributor
timestamp: March 18, 2020, 11:16:43 am
content: My first actions would be a signal integrity test: are all the voltages within the relevant logic level spec, are the setup/hold times observed, and are transitions clean. If not then that has to be sorted out first.Beyond that you have to define what tests you think are worth doing, especially the difference between basic functionality and parametric tests.What drivers were used in the PET? That should give you some clue.For DC testing I'm sure 3/5mA would be fine, but what about full speed tests? To a first approximation, CV = Q = It where C is the input capacitance, V is the voltage swing in time t. So the current to charge the load capacitance would be I=CV/t. At a guess, C=5pF (per input), V=3V (for TTL), t=5ns, giving 3mA. So, the 3/5mA output drive isn't wrong, but is close. That might matter if you are doing tight parametric tests, but is unlikely to be an issue if you are allowing plenty of margin in setup and hold times.What benefit do you expect from a current limiting resistor?Do also check whether the jellybean logic chips are OK. I've seen a 7404 (?07?) become faulty and fail to drive an unobtanium high voltage driver.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: March 18, 2020, 11:40:35 am
content: Quote from: tggzzz on March 18, 2020, 11:16:43 amTo protect the uP when there is a short in the DUT

author: tggzzz
author_rank: Super Contributor
timestamp: March 18, 2020, 11:45:08 am
content: Quote from: NivagSwerdna on March 18, 2020, 11:40:35 amOK, but don't forget to think about the V=IR drop and how that might affect signal integrity. That will require contemplating the DUT's datasheet, of course.You might consider doing the smoke test, then shorting out the resistors.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: March 18, 2020, 12:05:46 pm
content: Quote from: tggzzz on March 18, 2020, 11:45:08 amDatasheets for 6540 and 6550 devices seem as rare as bog roll.
Driving PMSM with ESC - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: December 20, 2018, 01:00:40 am
content: I have a 3-phase 6 pole permanent magnet synchronous motor that I want to drive from a cheap ebay electronic speed control. Not to do anything useful, just to see what happens. The motor has 3 hall effect sensors but I might try a sensorless controller. Motor is about 105m long and 60mm diameter. Came out of an automatic sliding door.I rotated it in a drill and it generated 17.85Hz and 5 volts. Say I want to go to much higher speeds. If I have a supply of 20VDC to the ESC, does this mean I can't or shouldn't rev the motor faster than the rpm at which it would generate 20 V peak AC?

author: Siwastaja
author_rank: Super Contributor
timestamp: December 20, 2018, 07:29:06 am
content: With the standard "optimum" 90 degree advancement, which most inverters, in most operating modes, try to tightly follow in a closed loop, the motor's back-EMF limits the current you can push into it - this basically means that available torque falls to zero when you hit the RPM you measured the "open circuit generator" voltage with. Including both mechanical and electrical losses, the actual RPM will be less. This is analogous to a circuit where you are charging a capacitor with a 20V voltage source - the current you can push through the parasitic resistances drops and finally is zero at 20V, so you can't charge it to any higher voltage (~ rpm).There is a remedy, namely field-weakening mode, which means deviating from the optimum 90 degree advancement and going over it, causing large reactive currents, which cancel out the permanent magnet field, reducing the RPM/V constant of the motor temporarily. This is only relevant when you need high speeds with small torque. It's likely the ESC won't perform in this mode, as their typical intended usage is driving propellers, meaning the mechanical loadincreaseswith speed, necessitatingincreasingtorque as well, so compromising the torque would be a dead end.Try it out - I'd guess your RPM will be somewhat limited, and the best way to overcome this is increasing DC bus voltage, not driving in field weakening mode.

author: Circlotron
author_rank: Super Contributor
timestamp: December 20, 2018, 12:00:49 pm
content: Quote from: Siwastaja on December 20, 2018, 07:29:06 amCool. Thanks.
Driving Stepper motor using 3.7V Li-Ion - Page 1
Forum section: electronics / projects

author: electroguy
author_rank: Regular Contributor
timestamp: November 27, 2012, 03:15:31 pm
content: Hi,Has anyone here had success (or failure?!) driving steppers using 3.7V Li-Ion?Need some advice for driving a stepper such as this:http://www.pololu.com/catalog/product/1204I realise that i won't be driving it to it's full potential, given that it can run up to 3.9V and single cell battery is usually less than this, but will i still get the majority of the power gm/cm (oz-in) listed?Motor won't be going overly fast, maybe 1 or 2 rps (60 to 120 RPM).I know there are some great stepper chips out there with current limit, etc... such as TI DRV8811 or Allegro A4988, but chips like these require a minimum Vin for motor to be about 8v (they use chopper current limiting, etc...)Although they *might* work with a lower Vin, I don't want to do this as it is out of spec according to the data sheet, so i am thinking of using something like this:http://www.pololu.com/catalog/product/2135Does anyone have any advice or experience for driving steppers from single cell 3.7V li-ion?

author: Kremmen
author_rank: Super Contributor
timestamp: November 27, 2012, 08:23:48 pm
content: You should be aware that the "nominal" voltage of a stepper has precious little to do with the actual voltage of the optimal power supply. The nominal voltage is the one that drives the nominal DC current through the motor stator winding through its DC resistance.The situation changes completely when you actually start stepping the motor. The instantaneous winding current is determined by the resistance and inductance of the winding, the applied voltage and elapsed time. When a DC voltage is applied to an ideal inductor, the current rises linearly from zero as a function of time. The slope is determined byt the inductance and applied voltage. So, the coil current does not rise instantaneously. If you supply only the nominal voltage then at even moderate step rates the coil current hasn't got time to raise to any useful level for torque production and you motor will either stall or never get to speed in the first place.The solution is to raise the supply voltage and limit the current at slow step ratesusing some PWM scheme. A popular mfg of stepper drives - Gecko - suggests the supply voltage should be 32 * sqrt(L) where L is the coil inductance in mH. In your motor the value is 1.7 mH resulting in recommended supply of 41 V. Quite far above 3.7 V.The fact is that you just won't get anything useful from the motor at such low supply voltages unless you are satisfied with dead slow motion.

author: electroguy
author_rank: Regular Contributor
timestamp: November 28, 2012, 11:29:11 am
content: Thanks. Looks like im going to have to step up the voltage...
Driving "STP1612PW05" IC for RGB LED - Page 1
Forum section: electronics / projects

author: amirkargar110
author_rank: Contributor
timestamp: October 16, 2018, 12:01:23 pm
content: helloI want to drive my RGB led (P/N:5050LED) with "STP1612PW05" IC,any body has the ready program of running this IC?I don't understand its datasheet and how does it work?could you help me?
Driving TEC elements - Page 1
Forum section: electronics / projects

author: blueskull
author_rank: Unknown
timestamp: July 16, 2016, 10:54:51 am
content: Recently I am playing with some temperature sensitive things so I think I can use TEC coolers to heat or cool the sensitive part.In this case, 0C~30C is fine, so I do not need accurate temperature control. However, I do need a simple and low cost solution.My question is, can I connect a TEC rated for maximum 3.6V into a 5V system, and drive it with unfiltered PWM? The 5V can be lowered to minimum 4.5V, but that is still more than the TEC's rated max voltage.

author: Pjotr
author_rank: Frequent Contributor
timestamp: July 16, 2016, 11:11:19 am
content: Quote from: blueskull on July 16, 2016, 10:54:51 amNO! The AC ripple current greatly impairs its cooling performance. You can use PWM (and it is almost always done) but you need to filter carefully to get the ripple current through the TEC as low as possible. Preferable < 10%.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 16, 2016, 11:25:32 am
content: The cooling power of the TEC follows a parabola, with a maximum cooling at about the maximum / rated current of the TEC. So more than the rate voltage will reduce the cooling effect. So a 3.6 V rated TEC at 5 V will have a similar cooling effect as at 1.4 V - less if cooling of the hot side is not perfect. This applies to the instant current with PWM too - so unfiltered PWM at 5 V is not a good idea. Even with just the nominal current it is not a good idea, as this will reduce the efficiency and lifetime of the TEC due to thermal stress.So it's better to add a resistor or use linear control of the current than using more than the nominal current/voltage.Also filtering with a kind of switched mode control (filter inductor and free wheeling diode) is an real option. There is no need to get the ripple really low. Something like a 10-20% ripple should not be a problem, so a capacitor parallel to the TEC is optional.
Driving the 113KHz Atomizer(Humidifier) - Page 1
Forum section: electronics / projects

author: LakshmiN
author_rank: Contributor
timestamp: April 26, 2021, 05:43:28 am
content: Hi,I'm trying to drive the 113KHz Atomizer with esp32(https://robu.in/product/dc-5v-ultrasonic-humidifiers-power-circuit-board-with-atomizing-chip/) with esp32But I do see that the atomizer tries to turn on and beep sound but I don't see any mist effect from the transducerThe circuit is similar to this:https://www.electroschematics.com/wp-content/uploads/2019/06/7-Atomizer-Driver-Blueprint.pngCode:#define LEDC_CHANNEL_0 0// use 4 bit precission for LEDC timer#define LEDC_TIMER_4_BIT 4// use 113KHz Hz as a LEDC base frequency#define LEDC_BASE_FREQ 113000#define LED_PIN 5void setup() {// Setup timer and attach timer to a led pinledcSetup(LEDC_CHANNEL_0, LEDC_BASE_FREQ, LEDC_TIMER_4_BIT);ledcAttachPin(LED_PIN, LEDC_CHANNEL_0);ledcWrite(LEDC_CHANNEL_0, 7);}void loop() {}Can anyone suggest what's going wrong here?

author: Marco
author_rank: Super Contributor
timestamp: April 27, 2021, 12:03:51 am
content: Why not just use the original driver board and just wire an I/O across the switch? Let the original driver worry about driving the transducer.

author: LakshmiN
author_rank: Contributor
timestamp: April 27, 2021, 02:52:22 am
content: Yeah, I tried that too connecting esp32 PWM directly(disconnected on board controller connection) to Mosfet on the original driver board and it didn't seem to provide the effect.

author: Marco
author_rank: Super Contributor
timestamp: April 27, 2021, 10:55:04 am
content: No, I don't mean the MOSFET ... I mean the main on/off switch on the driver board.Don't generate 113 kHz on the ESP32, just turn on the driver board. Might need to use a MOSFET if the switch carries power, but still that MOSFET would just be working at low frequency.

author: LakshmiN
author_rank: Contributor
timestamp: April 27, 2021, 01:19:56 pm
content: I didn't understandDriver board has Boost regulator and unknown microcontroller generating PWM @105KHz. Driver board alone works fineI'm trying to use PWM from esp32.
Driving ultrasonic transducers with motor full-bridge drivers - Page 1
Forum section: electronics / projects

author: KaneTW
author_rank: Frequent Contributor
timestamp: September 05, 2019, 07:18:02 pm
content: Motor full-bridge drivers (e.g. DRV8412) are mostly designed for inductive loads. I'm looking to drive 60W 40khz/100khz dual transducers with a static capacitance of 5nF and <25 Ohm resonance impedance with those.Ultrasonic transducers are a RLC series resonant, high-Q circuit, with the static capacitance in parallel.Is there anything to watch out for when driving potentially capacitive loads (at f < f0) with drivers designed for inductive loads? TI app notes (SLAA780A) just send the output directly to the transceiver, but that shows a lot of ringing in simulations. Adding some inductance and common-mode and differential capacitors helps a bunch, but leads to significant 2nd harmonic content at 40kHz switching frequency.Am I overthinking this? Most high-power applications just drive transducers with a square wave, so it can't be that difficult.
DRO design? - Page 1
Forum section: electronics / projects

author: Mrt12
author_rank: Regular Contributor
timestamp: July 04, 2018, 06:47:04 pm
content: Hi,I would like to make a DRO (dielectric resonator oscillator). I have some of those ceramic resonators here, for different frequencies - 2.5 GHz, 10 GHz, 12 GHz.I once made a DRO, but it was more or less designed empirically, and I assume I was just lucky that it worked :-) so I wonder whether there is a more systematic way.Is there anybody here who has experience with DROs?
Drop-in replacement for LM2576HVS-ADJ - Page 1
Forum section: electronics / projects

author: PinheadBE
author_rank: Regular Contributor
timestamp: March 07, 2022, 03:18:36 pm
content: Hi,I have a defective LM2576HVS-ADJ to replace in a studio DMX spotlight.Given that this part has become now unobtainium, I was wondering:1°) If I replace it with a LM2596HVS-ADJ, do I have to replace the output inductance with another value ?2°) Where could I reliably source a LM2576HVS-ADJ (preferably) or a LM2596HVS-ADJ (Not EBay, nor Ali, nor ....)Thanks for your inputEDIT: The input voltage is a solid 48 V. That's the reason I absolutely need a HV version of the chip

author: madires
author_rank: Super Contributor
timestamp: March 07, 2022, 03:34:49 pm
content: The LM2596 has a switching frquency of 150kHz vs. LM2576's 52kHz. So I'd assume you need to adjust the inductance (see the LM2596's datasheet for choosing the correct value).

author: thm_w
author_rank: Super Contributor
timestamp: March 08, 2022, 12:22:50 am
content: Looks like LCSC has a clone version:https://lcsc.com/product-detail/DC-DC-Converters_HGSEMI-LM2596HVS-ADJ-TR_C356713.htmlAnother option is to just get rid of the original circuit and wire in a different module.

author: Someone
author_rank: Super Contributor
timestamp: March 08, 2022, 02:18:37 am
content: Quote from: PinheadBE on March 07, 2022, 03:18:36 pmMultiple stockists are showing availability for that part, even if you only want single quantities:https://octopart.comOr use a non-adjustable version and change the feedback.
Dropping a 7V 10A PSU 1V - Page 1
Forum section: electronics / projects

author: ChristofferB
author_rank: Frequent Contributor
timestamp: October 17, 2020, 12:30:28 pm
content: Hi all!I'm in need of a dual tracking +-6V PSU delivering around 10A. It's for a modular rack so it's likely to draw much less.Funny thing, 6V is NOT a voltage offered in most low-cost (Mean Well etc.) series SMPS systems. I was going to use 2 isolated SMPS in series, center tap grounded.7,5V is however very available, and they can be trimmed down to 7.1V.So how do I best drop a 10A PSU from 7.1V to 6V ? (+-0.2V is propably ok).Two beefy series diodes bolted onto a fan cooled heat sink maybe? Wasting a bit of energy isn't a giant concern.Thanks!

author: Siwastaja
author_rank: Super Contributor
timestamp: October 17, 2020, 01:18:41 pm
content: I'd experiment modifying the feedback resistors, easily available following the voltage trim pot, to make the supply provide you with regulated 6V. The design of said Meanwell/similar supplies isverylikely stable at 6V even if the pot doesn't allow trimming it that far. You are only deviating some 15% of the official trimming range.

author: tunk
author_rank: Super Contributor
timestamp: October 17, 2020, 01:28:32 pm
content: I agree with Siwastaja, and a web search with these keywords may help:tl431 smps schematic

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 17, 2020, 01:30:51 pm
content: You may find that the onboard voltage trimmer that many PSUs have will get you there or close

author: ChristofferB
author_rank: Frequent Contributor
timestamp: October 17, 2020, 01:32:36 pm
content: That would be absolutely ideal! I don't have the PSU's yet, but does that mean that the voltage adjust pot is a smaller adjustable resistance in series with a fixed resistance?

author: Siwastaja
author_rank: Super Contributor
timestamp: October 17, 2020, 01:57:52 pm
content: I don't remember off-hand which way the pot works, i.e., it might be either a part of the top resistor or the bottom resistor of the feedback network.In any case, because it's just a finetune pot, it will have a fixed resistor in series.The chances are1) you have to add resistance in series with the trimmer2) you have to reduce resistance from whatever already exists in series with the trimmerIn both cases, it should be easy to trace on the PCB.Measure what there is and make small changes. For example, if you find a 10kOhm resistor, replace with a 8.2k or 12k resistor and see what happens.Do note that such hacks have their limits. If you want to modify the output voltage more than maybe 20%, you may need to redesign the supply.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: October 17, 2020, 06:00:24 pm
content: Thanks for the advice.I'll try it, I'm pretty sure it can be made to work. I'll update this thread when I get around to doing it, for future reference.--Chris
Drum Machine Alesis HR-16 Mods rant - Page 1
Forum section: electronics / projects

author: CaptDon
author_rank: Super Contributor
timestamp: September 19, 2024, 02:28:32 pm
content: I have an original gray HR-16 (not the B version). The O.S. and the 'sounds' are ROM's in sockets. The original version has 49 sounds, any 16 of which can be assigned to trigger from a specific MIDI note. Many folks were hot on the LinnDrum (often called the LM2 as it was a later version) sound mods for the Alesis HR-16. The mods could include an update to the HR-16 to make it an HR16B rev 2.0 just by swapping ROM/Eprom devices. So I get ready to buy a set of Eproms from the Ebay seller Vintage Synths and I ask a simple question "Do I still get at least 49 sound choices with the LinnDrum chipset? Do you have a list of the new sounds?" (I'd like to know what I am getting) The reply "No I don't". Does anyone here mess around with the old HR-16(B)?? Anyone have a downloadable pirate copy of what is already pirate-ware being sold on Ebay? Is the LinnDrum upgrade even worth the time in your experience? These HR-16's are still bringing north of $200.00 and I can't image why. Folks around the 2005 era used to simply give these things away. I may have paid $50.00 U.S.D. for mine around 1998. I gave it away and it was recently given back to me in working condition with the original battery!! Cheers mates!!

author: CaptDon
author_rank: Super Contributor
timestamp: September 20, 2024, 08:27:02 pm
content: I asked the seller "Are there still 49 sounds" and "Could you send me a list so I can see if they are worth the upgrade". The single reply answer "I don't know". I guess it is hard to know what you are selling when it is pirated pirateware even though the seller is an 'expert' on these things. Another Doubting Thomas moment, the machine uses 2 X 32 pin 256K X 8 memory as well as one piece of 28 pin 32K X 8 and his ad shows 3 pieces of 28 pin devices. Sounds like the home team is getting screwed. No thanks.
Drunk Ebaying! - Page 1
Forum section: electronics / projects

author: CrabxCore
author_rank: Contributor
timestamp: June 04, 2014, 10:05:27 pm
content: Hey everyone,Recently I bid on some old mil spec resistors on ebay, while a little drunkHere is the listing for anyone that wants to see it:http://www.ebay.com/itm/141295940590Anyways, while going through looking at all these awesome little resistors and googling data sheets I came across something different. I am hoping someone on the forum can help tell me what I am looking at. It appears to be a die of some sort.Also, If anyone wants to see more of what I ended up with just post what you want pictures of and I will do my best!Thanks,Crab

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: June 04, 2014, 10:55:57 pm
content: Looky like you gots yourselfs a thick film hybrid:http://en.wikipedia.org/wiki/Hybrid_integrated_circuit

author: CrabxCore
author_rank: Contributor
timestamp: June 04, 2014, 11:24:17 pm
content: Oh wow thats really cool!I put it under the microscope and took some pictures of it. Here is the album:http://imgur.com/a/5EIUS. You can see some areas that look like capacitors and either resistive elements or maybe p-n junctions?Thanks,Crab

author: echen1024
author_rank: Super Contributor
timestamp: June 05, 2014, 04:16:50 am
content: Ebaying drunk is never a good idea. If you're not careful, next thing you know is that 10GHz Agilent is yours!

author: KJDS
author_rank: Super Contributor
timestamp: June 05, 2014, 07:02:24 am
content: There's a Lange coupler on there

author: CrabxCore
author_rank: Contributor
timestamp: June 05, 2014, 07:46:33 am
content: Quote from: KJDS on June 05, 2014, 07:02:24 amJust looked that up. Looks like what I have! What would it be used for? I'm guessing it was for something military related as all the resistors I got are mil 55342 or something like that.
DRV8251 DC Brushed Motor Driver - Page 1
Forum section: electronics / projects

author: Tnixsw
author_rank: Contributor
timestamp: May 08, 2024, 12:42:59 am
content: Hi all,I was looking at using this device for a project that uses a 5V brushed DC motor for a printer mechanism.The device data sheet mentions that PWM can be used for speed control and that switching between driving and braking typically works best. This method allows full access to the current sense feature, which is not available during all switches OFF - (motor coasting).This seems contradictory to me as you are trying to drive the motor and then stop it in a single PWM period.I tried this and the motor doesn't seem happy.I would have thought the current sense might have been better utilized during coasting for speed control feedback by using the back EMF of the motor.I thought if someone has already used this device, they could share some experience.cheersTony

author: H.O
author_rank: Frequent Contributor
timestamp: May 08, 2024, 03:57:24 pm
content: I have not used this device and I'm not 100% sure but...The device uses a low side current sense resistor. This means that during the off period, if you use coast/all switches off, the current thru the sense resistor reverses which produces a negative voltage on the sense input, an event from which the sense amplifier in the chip then needs to recover - and this happens every PWM cycle.When using slow decay/both low side switches on, the current never flows thru the sense resistor during the off period of the normal PWM cycle, hence no negative voltage on the sense pin.Do note, however, that the device itself uses coast/all switches off during the current regulation off time.Hopefully (surely) someone will correct me if I'm wrong :-)

author: Tnixsw
author_rank: Contributor
timestamp: May 09, 2024, 04:22:05 am
content: Thanks for the reply.There isn't a current sense resistor in this device. It has an internal current mirror associated with each low side FET.It outputs a current proportional to the sensed motor current through each of the low side FETs, and with that you can use an external resistor to read a proportional voltage. Unfortunately, this only works when either of the low side FETs are on.cheersTony

author: H.O
author_rank: Frequent Contributor
timestamp: May 09, 2024, 05:41:17 am
content: Ah, you're using the DRV8251A, not DRV8251 - those are different...As it says in the datasheet, in order for the current to be properly sensed it has to flow from drain to source in the low side MOSFETs. With slow decay (both low side switches on) the current does flow from drain to source in one MOSFET hence it can be sensed. In fast decay (all switches off) the current flows in reverse, from source to drain, thru the diode so it can't be sensed.In my original post I wrote that the DRV8251 uses fast decay (all switches off) for current regulation but I must have misread that.
DRV8332 BLDC driver questions - Page 1
Forum section: electronics / projects

author: anvoice
author_rank: Frequent Contributor
timestamp: August 30, 2018, 09:17:33 am
content: I'm studying the datasheet of the DRV8332 motor driver (too big to attach) and had a couple of questions:1. The output inductor selection guide mentions that the inductors going to the motor phases should be = (Power voltage) * (delay) / ((Peak current) - (Average current)), where peak current = 10A, my average current should equal 5A, power voltage is 24V and delay is 250ns. It doesn't, however, say what the units of the inductance should be: nH or uH. Could anyone help me with that?2. The application diagram has current sense resistors going from three distinct ground pins to ground. If I understand correctly, there's no voltage-measuring capability built into the DRV8332, and they're implying I should get some op-amps then route the output of that to my microcontroller. At the same time, the device has overcurrent protection: would that imply that current sensing is not necessary unless I need to use the measured current for some application? It would be nice to omit the bulky current sense resistors from this design.Thanks a bunch.
DRV8332 problem with shunt - Page 1
Forum section: electronics / projects

author: mr1979
author_rank: Contributor
timestamp: August 28, 2017, 07:24:03 pm
content: I found problems reading current feedback through shunt resistor connected in a star topology due ti a poor layout. The resistance of the track was about 10mohm that is also value of shunt. This is my first experiance with a motor driver. Do you suggest to do only a better layout or do you think is better to use a current sense amplifier?Inviato dal mio PLK-L01 utilizzando Tapatalk
dry film in different colors? (solder resist) - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: June 16, 2024, 06:43:50 am
content: I got my laminations pretty good but I wonder if you can get solder resist dry film mask in a color other then green?I.e. yellowso you can do things like color different parts of the PCB a different color.anddo they have a specific product for text and labels?

author: quadtech
author_rank: Regular Contributor
timestamp: June 17, 2024, 02:58:18 pm
content: Dry film - not sure, but UV based solder mask is available in different colors.https://www.amazon.com/Solder-Curing-Light-Resistance-Circuit/dp/B0C5W3HFB9Interestingly, there is a multi-color Soldermask option now from JLCPCB which looks really cool -This Spectrum PCB is really cool -https://jlcpcb.com/help/article/552-How-to-design-multi-color-silkscreen-using-EasyEDA

author: coppercone2
author_rank: Super Contributor
timestamp: June 17, 2024, 04:50:47 pm
content: lol the gel, ok that stuff boils my blood.for the people that have a laser cutter ^