hybridfree/eevblog-posts huggingface dataset:
How to charge NiMH cell from single solar cell? - Page 1
Forum section: electronics / projects

author: Mad ID
author_rank: Regular Contributor
timestamp: July 06, 2017, 09:21:55 am
content: Hi,I'm having trouble finding a circuit which can charge 1.4V NiMH battery from a single solar cell.The cell is ExCellLight with 1.15V open circuit voltage. It's very small, I expect 100uA charging current in my application.The problem I have is that all of the energy harvesting circuits I've looked at require at least 2V battery voltage (e.q. two NiMH cells in series).The other problem is that standard boost converters like TPS610985 won't startup from a high-impedance source.If I connect it to a 1V power supply with 50R series resistor the TPS never starts, output voltage stays at 0.5V. The same thing if I connect them to the solar cell.Does anyone have an idea how to realize this circuit?Thanks!

author: tszaboo
author_rank: Super Contributor
timestamp: July 06, 2017, 09:35:08 am
content: Linear Technology has energy harvesting ICs, which work down to 0.2V. After that, you need a low IQ charger. Though, it is probably cheaper to buy bigger/more solar cell.

author: OiD
author_rank: Regular Contributor
timestamp: July 07, 2017, 03:02:09 pm
content: As NAND said, go for a dedicated IC for such low voltages and if nothing is stoping you go for a more suitable solar cell. All conversions lose some energy so the closer you get the better.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 07, 2017, 03:31:24 pm
content: Use a calculator solar cell?

author: edavid
author_rank: Super Contributor
timestamp: July 07, 2017, 05:22:28 pm
content: Use a QX5252F or other solar lawn light IC.Or, take apart a lawn light.

author: Audioguru
author_rank: Super Contributor
timestamp: July 08, 2017, 03:38:15 am
content: Quote from: edavid on July 07, 2017, 05:22:28 pmNo.A solar garden light circuit uses a 2V or more solar panel that charges the 1.4V battery through a Schottky diode. The circuit boosts the battery voltage to feed the 3V LED, it does not boost the solar panel voltage.

author: edavid
author_rank: Super Contributor
timestamp: July 08, 2017, 04:54:57 am
content: Quote from: Audioguru on July 08, 2017, 03:38:15 amYou can connect the solar cell to the battery input, and the battery where the LED would normally go.The QX5252 will operate on 0.9V.
How to check if there is a good signal on LAN9514's downstream Ethernet port - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: March 31, 2022, 05:19:11 pm
content: Hi,I am using this hub chip LAN9514 that has a USB in and 4xUSB "out" and 1xLAN "out" (i.e. downstream ports). It is connected through another IC of the same type. So this one is further down the SBU tree.The software guy has not developed any drivers/software yet. So, in order to test the PCB, how can I check if there is a good signal out of the LAN port without any software?If I plug it into a router the LED on the router initially blinks on and off and then becomes stable on. I assume that means the link is established and working.But on the LAN9514 side the link LED keeps blinking on and off at random rates/intervals.Any idea what that combination means? Is that enough to assume that the link is working correctly at least on the hardware or not?I was thinking to perhaps buy a Ethernet tester like this one, but not sure if it would show anything?https://www.amazon.co.uk/KOLSOL-Network-Standards-Distance-Function/dp/B08CMRCDNB/ref=sr_1_1_sspa?crid=10FAL9R96EXHJ&keywords=ethernet+tester+with+speed&qid=1648746613&sprefix=ethernet+tester%2Caps%2C110&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUE4NEczOE9BNEZJRUwmZW5jcnlwdGVkSWQ9QTAxNDE5OTUzTzI4T0hQUko2UlY4JmVuY3J5cHRlZEFkSWQ9QTAyNzk1NjkyUFRROFlKRkpTMDI0JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==Thank you

author: tooki
author_rank: Super Contributor
timestamp: March 31, 2022, 05:27:02 pm
content: Uh… connect your Ethernet port to a small Ethernet switch and see if the link status goes up? (I would assume that this would occur even without software initialization.)

author: ricko_uk
author_rank: Super Contributor
timestamp: March 31, 2022, 06:14:05 pm
content: Thank you Tooki,I updated the OP...If I plug it into a router the LED on the router initially blinks on and off and then becomes stable on. I assume that means the link is established and working...But on the LAN9514 side the link LED keeps blinking on and off at random rates/intervals.Any idea what that means? Is that enough to assume that the link is working correctly at least on the hardware?Thank you

author: nctnico
author_rank: Super Contributor
timestamp: March 31, 2022, 11:06:44 pm
content: Connect it to a switch without any network traffic to avoid blinking a combined link / activity LED.

author: ricko_uk
author_rank: Super Contributor
timestamp: April 01, 2022, 01:22:26 am
content: Thank you nctnico,I did think so but wasn't sure that was 100% correct in all cases.
How to check stability/integrity of voltage reference IC? - Page 1
Forum section: electronics / projects

author: Red_Micro
author_rank: Regular Contributor
timestamp: January 05, 2021, 10:17:08 pm
content: I'm using TL431 shunt regulator as the voltage reference of 2.5V for an ADC. If I don't add a cap at the output, this introduces non-linearities in the ADC measurements. When I add a 10uF cap, the reference becomes more stable reducing accuracy errors in ADC. My question is how I can measure or see this behavior with let's say an scope? How can I see this instability of the regulator to understand how it changes when sampling?

author: bob91343
author_rank: Super Contributor
timestamp: January 05, 2021, 10:40:31 pm
content: You could build two of them and use a differential probe.
How to Choose a Switching Mode Power Supply - Page 1
Forum section: electronics / projects

author: phil_jp1
author_rank: Regular Contributor
timestamp: August 05, 2012, 07:05:33 pm
content: Hey everyone,I wrote a little article where I explain what different parameters from switching power supplies datasheets mean.So, if anyone needs to make a heads or tails of info in a psu datasheets - you're welcome to read my article:http://goo.gl/Hxsnrp.s. hope that Curiosity rover lands safely.
How to choose common mode choke for reducing EMI due to vibration motor - Page 1
Forum section: electronics / projects

author: Sai teja
author_rank: Regular Contributor
timestamp: November 28, 2018, 09:18:21 am
content: Hi ,In my application, I am using cointype vibration motors and ERM vibration motors for giving vibration alerts.As per the reference provided below, a common mode choke could be placed to reduce EMI and improve EMC. However the specifications of the common mode choke are not provided. Can any one guide me through the process of selecting the common mode choke for vibration motor?https://www.precisionmicrodrives.com/content/ab-005-electromagnetic-compatibility-emc-emi-for-vibe-motors/Specification of ERM vibration motor :Rated Voltage : 8VRPM : 7500Operating current : 350 milli ampsSpecification of cointype vibration motor :Rated Voltage : 5VRPM : 12000Operating current : 100 milli ampsSomeone help me in this regard.

author: TimNJ
author_rank: Super Contributor
timestamp: November 29, 2018, 11:15:55 pm
content: I don't know anything about ERM vibration motors, but, I think you should start by analyzing the current EMI profile of the device + driver and try to identify the problem frequencies. Once you understand what your problems are, you can better select or design a component to help solve it.

author: DaJMasta
author_rank: Super Contributor
timestamp: November 29, 2018, 11:35:12 pm
content: Do you already have the cap very close to the motor terminals? From the link you provided, a 100nF MLCC cap alone seems to do a great job as a start. Good decoupling of the motor driver could also go a long way to keeping noise out of the power system.

author: Sai teja
author_rank: Regular Contributor
timestamp: November 30, 2018, 05:49:16 am
content: I placed cap as shown in the reference. I am wondered how to choose choke for motor.
How to close a switch - Page 1
Forum section: electronics / projects

author: J4e8a16n
author_rank: Regular Contributor
timestamp: April 01, 2016, 09:38:43 pm
content: Hi,When the voltage rises higher than the zener diode voltage threshold the lamp is on.How can I manage for this to happen instantly (no relay)?JPD

author: Andy Watson
author_rank: Super Contributor
timestamp: April 01, 2016, 09:57:21 pm
content: "Instantly" ?I'm not sure I understand your problem. Are you saying that you want the lamp to go to full brightness when the zener starts to conduct? If so, use the zener to trigger a thyristor.

author: dacman
author_rank: Frequent Contributor
timestamp: April 01, 2016, 09:59:47 pm
content: I'd suggest hooking an op amp up as a comparator.

author: J4e8a16n
author_rank: Regular Contributor
timestamp: April 02, 2016, 10:08:41 am
content: Hi,Thanks for your suggestions.I will try themJPD

author: Krampmeier
author_rank: Regular Contributor
timestamp: April 02, 2016, 02:48:27 pm
content: Another option with low part count would be a shunt voltage reference (such as the TL431) and a transistor instead of the zener diode.http://www.reuk.co.uk/TL431-Battery-Voltage-Monitor.htmwill give you a starting point.

author: J4e8a16n
author_rank: Regular Contributor
timestamp: April 02, 2016, 03:18:31 pm
content: I will try that as this is for a battery charger;o)JPD
how to compensate Vcb transconductance modulation in BJT CC CE - Page 1
Forum section: electronics / projects

author: strawberry
author_rank: Super Contributor
timestamp: December 17, 2021, 12:40:01 pm
content: is there a circuit that could do?

author: razvan784
author_rank: Regular Contributor
timestamp: December 17, 2021, 08:51:58 pm
content: Cascode?

author: TimFox
author_rank: Super Contributor
timestamp: December 18, 2021, 08:56:33 pm
content: Another advantage to the cascode connection (base of upper transistor coupled, possibly through a capacitor, to the emitter of lower transistor) is that the base currentIB1of the input transistor is also modulated byVCB. When that current flows through the source impedance, it imposes a voltage at the input which is a non-linear function of the input voltage. Since that voltage actually exists at the input terminal, the non-linear distortion cannot be removed by negative feedback, which only changes the gain for the parasitic voltage. The cascode with the upper transistor tries to keepVCBof the input transistor constant as the actual input voltage changes, thus reducing the unwanted change in input transistor base current.

author: mawyatt
author_rank: Super Contributor
timestamp: December 19, 2021, 12:04:22 am
content: There's a discussion of a cascode like amplifier that you might find useful, see post #9https://www.eevblog.com/forum/rf-microwave/common-gate-wideband-rf-amplifiers/Best,

author: David Hess
author_rank: Super Contributor
timestamp: December 19, 2021, 01:19:42 am
content: A cascode is one way. Another way is to add emitter degeneration.
How to connect a piezo speaker to a microcontroller? - Page 1
Forum section: electronics / projects

author: zapta
author_rank: Super Contributor
timestamp: January 17, 2014, 06:41:01 am
content: I have an AVR atmega328P MCU that generates 5V square wave 2-4Khz and I would like to connect to it a no name 10mm piezoelectric passive sounder I picked at a local surplus store. It measures as 10nF but don't know its inductance. I read somewhere that the MCU needs protection because mechanical impacts on the piezo, will send high voltage back to the MCU and damage it.I am looking for a simple way to safely connect the piezo the MCU. Any suggestion how to do it? For example is this a safe and reasonable way? Should I add a serial resistor between the diodes and the piezo to limit the current due to the piezo's capacitance?

author: miceuz
author_rank: Frequent Contributor
timestamp: January 17, 2014, 07:54:35 am
content: Piezo element is capacitive, so you want to drive it via a transistor as it takes relatively big gulps of current on every on and off. That and possible high voltage spikes as you've mentioned

author: zapta
author_rank: Super Contributor
timestamp: January 17, 2014, 04:51:45 pm
content: Thanks miceuz, that's simple enough. I will give it a try.I saw also similar circuits but with a additional diode in parallel to the resistor.

author: nctnico
author_rank: Super Contributor
timestamp: January 17, 2014, 06:36:24 pm
content: Quote from: miceuz on January 17, 2014, 07:54:35 amIf you replace the R* with an inductor then you double the swing.

author: zapta
author_rank: Super Contributor
timestamp: January 17, 2014, 10:01:58 pm
content: Quote from: nctnico on January 17, 2014, 06:36:24 pmHow do I choose the inductance? (assuming frequency and piezo's datasheet are given).

author: nctnico
author_rank: Super Contributor
timestamp: January 17, 2014, 10:18:36 pm
content: Quote from: zapta on January 17, 2014, 10:01:58 pmSomewhere around 5mH to 10mH should do. You should do the math to determine how long you can turn the transistor on without saturating the inductor. The duty cycle should also be less then 50%.

author: Zero999
author_rank: Super Contributor
timestamp: January 17, 2014, 11:20:40 pm
content: You should be able to drive a piezo directly from an MCU output and don't worry about the diodes, the MCU has them built in. Just connect the piezo directly to the MCU IO pin.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: January 17, 2014, 11:23:28 pm
content: I am also driving the piezo directly from the mcu pin thru a 100n cap without any problems.

author: Zero999
author_rank: Super Contributor
timestamp: January 18, 2014, 01:55:16 pm
content: A series capacitor is not a bad idea is it blocks DC which can be bad for piezos.For more volume, connect the piezo between two I/O pins and drive them out of phase with one another.
How to connect an atomizer disc and Computer fan - Page 1
Forum section: electronics / projects

author: CAMPPAIN
author_rank: Newbie
timestamp: December 10, 2023, 08:40:11 pm
content: Hello Everyone. I hope this makes sense. But I am trying to connect an atomizer disc (like the ones used for oil diffusers) and a water-resistant computer fan to operate from the same power source (a portable battery preferred).I want to power two atomizer discs and possibly 3 fans to help pull the mist up and through some pipes. The fans are 12v and the atomizer discs are 4.5 - 5.0 working voltage.Is this possible and if so how would I have to wire this up?Thank you for any and all help.
How to connect ECL output to 50 Ohm load? - Page 1
Forum section: electronics / projects

author: Mrt12
author_rank: Regular Contributor
timestamp: August 06, 2024, 06:46:49 pm
content: Hi,I am currently thinking about the following.I have a MC100LVEP16 ECL driver. Its outputs go to an SMA connector each, and on the receiver side I plan to add the Thevenin parallel termination resistors. I think this should work, as the ECL output sees a 50 Ohm transmission line, that is terminated in 50 Ohms at the far end, so it should be good.However, what can I do when I want to connect the output to an oscilloscope? this will present a 50 Ohm load to ground, so it will not work in that case. And when I place the Thevenin termination resistors close to the ECL output, I think it is wrong because, as far as I understand, the terminations shall be at the load and not at the source, right?So how should I design my ECL output, such that it will work with a 50 Ohm load to ground as well?
How to connect negative resistance ? - Page 1
Forum section: electronics / projects

author: Michael George
author_rank: Contributor
timestamp: October 02, 2015, 01:16:30 am
content: I was reading this article about negative resistance:https://www.maximintegrated.com/en/app-notes/index.mvp/id/1868Would you tell me where the two terminals of negative resistance are, Please ?Any resistor have two terminals. If I made a negative resistance as shown in the figure, Where are the two terminals? I need to connect negative resistance in series (or in parallel) with other positive resistors but I don't know how, because I don't know were the terminals of the negative resistor are.there are three possibilities in my mind:1- Two terminals are Vin and Vo.2- Vin and ground.3- Vo and ground.Thank you very much,

author: Paul Rose
author_rank: Regular Contributor
timestamp: October 02, 2015, 02:07:06 am
content: between Vin and groundseehttps://en.wikipedia.org/wiki/Negative_impedance_converter

author: Michael George
author_rank: Contributor
timestamp: October 02, 2015, 08:11:43 am
content: @Paul RoseThank you for answering my question, I would be very grateful if you would tell me more about this circuit.Upon your answer "Vin is one of the negative resistor terminals". I will connect Vin to a terminal of a positive resistor. so that they are in series. I expect that the circuit will work like a short circuit, Am I right? If no, How can I connect a positive resistor with the negative resistor?

author: Dave
author_rank: Super Contributor
timestamp: October 02, 2015, 11:28:32 am
content: It wouldn't act like a short, more like a comparator.If you applied a positive voltage to the input (like in your example), the opamp's output would slam into the positive rail.If you applied a negative voltage, it would slam into the negative rail.You can't have it behave like a short, because that would mean that it should be able to pull an infinite current, which would only be possible if there was an infinite voltage across resistor R3.

author: Michael George
author_rank: Contributor
timestamp: October 02, 2015, 04:47:46 pm
content: So, How can I connect a series positive resistor to a negative resistance op-amp?

author: Dave
author_rank: Super Contributor
timestamp: October 03, 2015, 04:03:49 am
content: The same way you just did.
How to connect power to MT6820-B controller board - Page 1
Forum section: electronics / projects

author: omer987
author_rank: Newbie
timestamp: January 15, 2022, 11:23:38 pm
content: How the power and ground wires from 5V 2A power supply should be connected to that board configuration:https://content.instructables.com/ORIG/FIV/93BN/KQZ7IZ6G/FIV93BNKQZ7IZ6G.jpg?auto=webp&frame=1&width=1024&height=1024&fit=bounds&md=266b8e602b50194bce6f0f6f734338b5Thanks in advance
How to connect the ID-NET signal wires  to maiboard  - Page 1
Forum section: electronics / projects

author: colinhnu
author_rank: Newbie
timestamp: October 10, 2018, 08:26:38 am
content: AS the images showing the function of ID-NET NETWORK.I dont know how to connect ID+/ID- signal wires to my mainboard CPU.ID+/ID- is I2C wire? RS485 wires or any other kind of wires,or add another IC to realize this ID-NET function. if someone knows,PLS help.Thanks.
How to connect the input of common collector ? - Page 1
Forum section: electronics / projects

author: Michael George
author_rank: Contributor
timestamp: September 28, 2015, 09:00:52 pm
content: I would like to know what considerations I should keep in mind while connecting input to a common collector (emitter follower) configuration. Would you tell me the rules of thumb, please ?If I want to connect the cell phone output (earpiece) or PC's output or any other input to the common collector input, Does it affect the base voltage or base current ? or should I change the values of bias resistors ?Is there limitations of input source voltage or current ?I mean an input voltage source can be in mv or in 10's of volts. Does the circuit accepts all kinds of inputs?Can I measure the input impedance of transistor using a multi-meter instead of calculating it ? Can I do the same thing for the input source?Sorry about asking too many questions, and thank you very much.

author: Fank1
author_rank: Regular Contributor
timestamp: September 28, 2015, 11:05:52 pm
content: Start here, some good tutorials in every day context.http://my.integritynet.com.au/purdic/index.html
How to control DC 30 amps and pneumatic central lock valve - Page 1
Forum section: electronics / projects

author: tlhsglm
author_rank: Contributor
timestamp: December 27, 2019, 06:16:06 am
content: Hi fellows,1- I have to control(just on/off) a mini compressor, 12v 21 amperes.What is the fastest way to do this?2- I will use a valve that drives 2 cylinders.That valve has a specialy, it have central locking, when i lift the load with cylinders, i will lock the valve to prevent load go down.This is important, i dont want compressor to work always.when i want the load to go down, i will simply make valve to stop locking.Is anybody work with this valves?How can i do that?Valve is 12v 4W.

author: Kalin
author_rank: Regular Contributor
timestamp: December 27, 2019, 04:31:03 pm
content: Some more information will be needed about the valve and what exactly you are looking for to control it, but for 12V 30A I would either use a Solid State Relay or a contactor. What are you using for process control, ie: do you have a PLC or are you planning to use an arduino or is this entirely discrete controls(pushbuttons and limit switches)?

author: i_am_fubar
author_rank: Regular Contributor
timestamp: December 27, 2019, 05:14:47 pm
content: 30A 12v is well within MOSFET territory if you want solid state. But SS relay is also option
How to control multiple micro stepper motor using a microcontroller ? - Page 1
Forum section: electronics / projects

author: NinjaCoder
author_rank: Newbie
timestamp: January 22, 2017, 03:05:32 am
content: I found cool little micro stepper motors off Aliexpress (Links Down). Each stepper require 4 wire and i require to control12 stepper motorusing a microcontroller what are viable option'sMicro Stepper Ali Link :https://www.aliexpress.com/item/50pcs-2-Phase-4-Wire-Micro-15-Step-Motor-Screw-Rod-Stepper-Stepping-Motor-Free-shipping/32222560547.html

author: ataradov
author_rank: Super Contributor
timestamp: January 22, 2017, 03:33:21 am
content: They are standard bipolar motors. The easiest way to control them is to use a driver IC. The popular ones are Allegro A4988 and TI DRV8825.They will take step and direction inputs, so you still will need 24 GPIOs on a micro.

author: NinjaCoder
author_rank: Newbie
timestamp: January 22, 2017, 03:51:34 am
content: Can we use shift registers for multiplexing ?

author: ataradov
author_rank: Super Contributor
timestamp: January 22, 2017, 03:56:52 am
content: For step and direction - sure. They must have LOAD pin that sets all outputs to a new value at the same time. But you still need a driver ICs.It may be possible to actually drive motor windings directly from shift registers, but that may get sketchy for production devices. For experiments, I did try to drive them from MCU pins directly and it worked fine, but obviously exceeded absolute maximum ratings on the MCU, so not something you want to do on real devices.

author: NinjaCoder
author_rank: Newbie
timestamp: January 22, 2017, 04:22:40 am
content: So i decided to go with A4988 and i only need half of stepper working at a time ( 6 x A4988 ) ie 12 gpio pin and a control input to switch between the inputs ! How can i implement switching between the inputs ??

author: ataradov
author_rank: Super Contributor
timestamp: January 22, 2017, 04:27:42 am
content: A4988 has enable input. Use that to control what drivers are enabled at what time.

author: mathsquid
author_rank: Frequent Contributor
timestamp: January 22, 2017, 03:36:18 pm
content: Quote from: NinjaCoder on January 22, 2017, 03:51:34 amYes. I built a CNC controller that uses two or three daisy-chained 74HC595 shift registers to let me control three bipolar stepper motors using 3 pins on a microcontroller. There's no reason you couldn't daisy-chain more 595s to control 12 stepper motors.For each stepper motor, I have a cheap ebay-sourced driver to power the motor.
How to convert HDMI to MIPI DSI  (1920x1080) - Page 1
Forum section: electronics / projects

author: luigi
author_rank: Newbie
timestamp: February 20, 2019, 04:50:17 pm
content: I am trying to drive a FullHD LCD display from HDMI signal.The display requires MIPI DSI signal and for that I will need to perform this conversion. The de facto standard IC for this job is the TC358779XBG/TC358870XBG for UHD. (The datasheet is attached)However in the datasheet available to download from Toshiba it is not specified how to configure the chip's internal registers by the I2C interface.Without that information the chip is useless. And I guess that this lack of information is due to something related to the HDMI license or whatever other commercial reason.I must integrate the chip into my own board so I can't use the cheap chinese boards already available.I believe that this kind of conversion is possible using FPGA but that is out of my current skill set.I am aware of the project from hackaday.io using Spartan6 but probably will require me to customize the code to fit my particular LCD.Anyone has any suggestion regarding these comments?

author: Andrey_irk
author_rank: Regular Contributor
timestamp: February 21, 2019, 12:59:16 am
content: Yeah DS for the chip doesn't seem to be available. I've only found a thread on NXP's website where a guy was trying to create a driver for it.https://community.nxp.com/thread/481534There is his mail. Try to contact him, maybe he'll help.Did you consider using microcontrollers to do that? I know that it'll be more labour-intensive (even if you find one supporting both interfaces), but it may be better than paying $$$ for a datasheet.In the thread the other guy mentions I.MX 8M evaluation kit that is exactly what you're trying to build.

author: Andrey_irk
author_rank: Regular Contributor
timestamp: February 21, 2019, 01:05:49 am
content: https://datasheet.octopart.com/TC358870XBG(EL,H4)-Toshiba-datasheet-33023052.pdfSimilar thing, but with all the necessary information.

author: ebclr
author_rank: Super Contributor
timestamp: February 21, 2019, 03:53:16 am
content: https://item.taobao.com/item.htm?spm=a230r.1.14.67.34ea5e89LOPd86&id=545962298653&ns=1&abbucket=20#detail

author: luigi
author_rank: Newbie
timestamp: February 23, 2019, 03:58:25 am
content: Quote from: Andrey_irk on February 21, 2019, 01:05:49 amI think you just saved me $10K.Somehow I did not look on Octopart, because I assumed that all PDFs available online were equal than the first 5 results on Google...Thanks!
How to cool SMT power packages and measure its temperature? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: November 18, 2018, 04:21:25 pm
content: Let's say I have a SMT power transistor in DPAK. How do I cool it and allow me to take temperature measurement of the heatsink?

author: SeanB
author_rank: Super Contributor
timestamp: November 18, 2018, 07:37:28 pm
content: Do it the recommended way the manufacturers use. Take the heatsink and drill a 1mm hole through it to contact the middle of the rear surface of the package, mount the device and use a ( preferably calibrated) welded tip thermocouple and a blob of heatsink compound to measure the temperature. Caution is that the thermocouple will be in electrical contact with the device, so will have the same voltage excursions as the device.Less accurate is to place the thermocouple on the heatsink next to the device, insulated by 2 thicknesses of Kapton tape from the device and heatsink, and taped down so it is firmly in contact with the side of the device but is still insulated. Will have a constant temperature difference to true temperature of the device, but at least will give you an indication within 5C or so of actual base of device temperature.

author: technix
author_rank: Super Contributor
timestamp: November 18, 2018, 10:19:16 pm
content: Quote from: SeanB on November 18, 2018, 07:37:28 pmI don’t really need the accurate temperature here, just a rough ballpark reading for implementing an overheat protection. Is there any simpler solution like place a temperature sensor chip somewhere and thermally bond it to the same heat sink as the power MOSFET?

author: langwadt
author_rank: Super Contributor
timestamp: November 18, 2018, 10:21:54 pm
content: Quote from: technix on November 18, 2018, 10:19:16 pmcan't use a protected mosfet?

author: technix
author_rank: Super Contributor
timestamp: November 18, 2018, 10:26:24 pm
content: Quote from: langwadt on November 18, 2018, 10:21:54 pmThe device in question has a USB uplink. Sure I can use a protected MOSFET but I also need to let the main MCU know that the thermal protection has tripped. So instead of a protected MOSFET I would prefer a temperature sensor and a normal MOSFET, and use the MCU to implement the thermal protection with uplink. It is cheaper and serves my purpose.

author: langwadt
author_rank: Super Contributor
timestamp: November 18, 2018, 11:59:47 pm
content: Quote from: technix on November 18, 2018, 10:26:24 pmthere are plenty of cheap switches with temp/current protection and error output, and you can toast a fet faster than an external temperature sensor can reactso calculation power dissipation would probably be a safer option

author: technix
author_rank: Super Contributor
timestamp: November 19, 2018, 05:04:58 am
content: Quote from: langwadt on November 18, 2018, 11:59:47 pmHow do I do that in a constant current load? Just rely on the input current and input voltage sense lines?
how to copy msp340f673x - Page 1
Forum section: electronics / projects

author: cciollolo
author_rank: Newbie
timestamp: September 20, 2016, 05:29:17 pm
content: hi guys i have a problem : i must copy one chip msp340f673x with Spy Bi-Wire connection . I know nothing of these chips, but i tried with IAR and CCS but i didn't find the option to read from the chip the flash,ram,fram. If it is possible ,i think to buy the lanchpad and mod them to program my chip .Thanks in advance !

author: Fred27
author_rank: Unknown
timestamp: September 20, 2016, 05:37:05 pm
content: You need a bit of software called mspflasher. It can read and write from the flash memory on the chip (unless it's been deliberately protected). It's free and can be downloaded from TI.Any of the newer Launchpads (not the G2) will provide the hardware (FET) needed to connect to it.

author: cciollolo
author_rank: Newbie
timestamp: September 20, 2016, 07:16:29 pm
content: hi fred27 thanks so much for the reply, i would buy msp-exp430g2 and connect the 2 wire SBWTDIO /SBWTCK (and power) to my chip . Is it possible ? if the chip is protected , i can't read and write or only write ? should i program the chip with specific program to read the ram or fram memory ?

author: Fred27
author_rank: Unknown
timestamp: September 21, 2016, 08:00:35 am
content: No - any MSP430 Launchpad *except* the G2. Try the F5529 or any of the FR ones.The documentation with mspflasher will explain how to use it.

author: cciollolo
author_rank: Newbie
timestamp: October 24, 2016, 09:29:02 am
content: Hi fred ... I bought the lauchpad 5529 and i tried to read the chip , but appears " the debug interface to the devices has been secured ". Is there a possibility to read this device ? The device should be mps430fr57x and i seen that there are another 2 pins (13 p2.0 and 14 p2.1) that are connected with 2 pad for programming contact .

author: Fred27
author_rank: Unknown
timestamp: October 24, 2016, 10:49:09 am
content: I don't think so. It's possible to protect the firmware on an MSP430. It sounds like someone has done that - presumably to stop you copying it!Sent from my Nexus 6 using Tapatalk
How to create a capacitive touch pad in Kicad? - Page 1
Forum section: electronics / projects

author: redgear
author_rank: Frequent Contributor
timestamp: August 30, 2020, 03:11:17 pm
content: I am trying to create a touch pad for use with the CAP1203 IC. How do I create a rectangular touch pad in Kicad?Something like this:Thanks

author: janoc
author_rank: Super Contributor
timestamp: August 30, 2020, 04:36:06 pm
content: Create a new footprint and draw this as a pin. There are plenty of options for the pin shape in Kicad.

author: langwadt
author_rank: Super Contributor
timestamp: August 30, 2020, 04:37:53 pm
content: create a new foot print with one smd pad, shape rectangle with rounded corners

author: redgear
author_rank: Frequent Contributor
timestamp: August 30, 2020, 04:40:16 pm
content: Quote from: janoc on August 30, 2020, 04:36:06 pmThanks....I will try doing it.Quote from: langwadt on August 30, 2020, 04:37:53 pmThank you. I cannot use a rectangle, as you can see, the shape is not closed.Edit: I tried but I am not able to create a shape like the one in the image. I can only create a rounded rectangle footprint.

author: langwadt
author_rank: Super Contributor
timestamp: August 30, 2020, 05:03:09 pm
content: Quote from: redgear on August 30, 2020, 04:40:16 pmbut your drawing is just a rounded rectangle, it just shows the trace connecting to it

author: redgear
author_rank: Frequent Contributor
timestamp: August 30, 2020, 05:23:18 pm
content: Quote from: langwadt on August 30, 2020, 05:03:09 pmI guess no.Thisis a Sparkfun breakout board in a different shape. You can see that the shapes do not complete.

author: janoc
author_rank: Super Contributor
timestamp: August 30, 2020, 06:36:59 pm
content: Quote from: redgear on August 30, 2020, 05:23:18 pmOf course those shapes "do complete" (are closed). The lines going out of them are traces added after the shape has been placed on the board in order to connect them to the connector/header pins.I think you should have a look at the Kicad tutorials that show how the PCB layout actually works ...
How to create a simple HV PWM generator - Page 1
Forum section: electronics / projects

author: DejanC
author_rank: Regular Contributor
timestamp: January 05, 2024, 03:46:43 pm
content: Hi,I would like some help in creating a safe but high-frequency (as much as is possible) HV generator using some simple components. I know I need a signal generator, a gate driver and possibly some isolation. Can anyone provide some reference or a circuit they have come across that is able to do this?400 Vpp and up to 10 MHz (maybe less) would be ideal.

author: DejanC
author_rank: Regular Contributor
timestamp: January 05, 2024, 07:08:39 pm
content: BUMP ^

author: inse
author_rank: Super Contributor
timestamp: January 05, 2024, 07:13:56 pm
content: Patience you must have, my young Padawan. Have patience and all will be revealed.

author: DejanC
author_rank: Regular Contributor
timestamp: January 05, 2024, 07:25:52 pm
content: Patience is a weak point for sure. I asked Chat GPT but wondering if anyone has had any experience building one, or pointers on what to consider.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: January 06, 2024, 10:29:21 pm
content: Quote from: DejanC on January 05, 2024, 03:46:43 pmYou have not mentioned power, or loads, but 400V at 10MHz is a RF transmitter.Your title mentions PWM, but you give no info on what range or step size.This also looks like a duplicate thread.

author: inse
author_rank: Super Contributor
timestamp: January 06, 2024, 10:31:26 pm
content: I was thinking the same and smiling to myself what might happen once this would go operational
HOW TO CREATE FEEDBACK LOOP IN HF ultra-wideband - Page 1
Forum section: electronics / projects

author: genekuli
author_rank: Newbie
timestamp: January 23, 2021, 02:26:55 am
content: If I hook up a HF ultra-wideband (UWB) amplifier with a transmitting UWB antenna (out) and a receiving UWB antenna (in) and have the antennas very close (few inches) to each other inside a metal box (~40cm) so as to produce a feedback loop, then due to the noise and harmonics of the over-driven amplifier clipped-waveform, it would then add more frequencies with each loop, resulting in an exponential growth in the amount of frequencies (to the limit of the amplifier and antennas), is that correct?
How to create multiple simultaneous signal sources from a single reference sourc - Page 1
Forum section: electronics / projects

author: john1998
author_rank: Newbie
timestamp: July 09, 2018, 02:27:41 am
content: I wanted to build a circuit which would produce a set of signals of different frequencies in different channels simultaneously using a single reference source. I also want the frequencies to be changeable. I am looking to generate frequencies in kHz and MHz range. On searching on the web I came across PLL. I wanted to know if I can do it using PLL or any other methods. It should be fully analog.

author: Nitrousoxide
author_rank: Regular Contributor
timestamp: July 09, 2018, 12:34:25 pm
content: What do you mean by "signals"? Are these just pure CW tones?What frequency is the source? Are you going to divide or multiply the base clock?What range exactly do you need? What is the minimum frequency spacing required?When you say analog, do you mean discrete parts? Are you allowed to use CMOS/TTL components?I would highly advise doing this in discrete/analog form unless you had a really good reason as digital is simpler and faster. There are clock management IC's that can do this already.However, a PLL will work. Here is a good TI app note on fractional PLL's:http://www.ti.com/lit/an/swra029/swra029.pdf

author: David Hess
author_rank: Super Contributor
timestamp: July 09, 2018, 04:15:14 pm
content: PLL (phased locked loop) frequency multiplication will work but is not all analog since it requires a digital divider. Another good option is to use DDS (direct digital synthesis) which relies on a phase accumulated and DAC and is available in a single IC.What kind of frequency resolution do you want? PLL frequency synthesis gets complicated if you want greater resolution than the reference frequency.
How to deal with EMC  - Page 1
Forum section: electronics / projects

author: old gregg
author_rank: Regular Contributor
timestamp: December 27, 2015, 06:52:46 pm
content: Hi,I've idea for producing in small quantity some electronic devices. But I started looking around and came the EMC europe thingy.It's a bit of a blur and obviously I don't have money to make tested my product by laboratories. Although it seems that it is not necessary for selling (otherwise how to explain the free availability of tube amps and such full of Non RHOS substances products).Could someone explain a bit more about it with pratical exemple ?thanks

author: old gregg
author_rank: Regular Contributor
timestamp: December 28, 2015, 12:33:10 pm
content: Hi,That the conclusion I reached as well, I just needed to be confident enough about my design to be EMC compliant. But with that kind of legislation, we're never sure enough.thanks.

author: acbern
author_rank: Frequent Contributor
timestamp: December 29, 2015, 09:24:33 pm
content: Quote from: blueskull on December 27, 2015, 07:01:51 pmThats actually not true. Not all products need a CE mark. There is a list of products that need it. Others don't. That does not necessarily mean that you do not need to comply with EMC requirements. What exactly is the question.See also here:https://www.eevblog.com/forum/projects/selling-your-product-in-the-eu-what-kind-of-regulatory-requirements-am-i-lookin/msg706370/#msg706370
How to decide dimensions of PCB heatsink(Need help plese) - Page 1
Forum section: electronics / projects

author: Sai teja
author_rank: Regular Contributor
timestamp: September 13, 2017, 06:58:15 am
content: Hello, I am using MCP73213 IC for charging my 2S Li Ion battery. I want to use this IC for 1 ampere charging during constant current charge cycle.My specifications are as follows.Input source voltage : 9 volts(10 % accurate)charge current : 1 ampere during constant charging cycleMax power dissipation for such application is as follows : (9.9 volts -6 volts)* 1 ampere = 3.9 WThermal resistance of IC : 62 C/WSo rise of temperature during max power dissipation : 62*3.9 = 241 centigrade.But according to datasheet, IC will die at 150 centigrade.Datasheet of MCP73213 :http://ww1.microchip.com/downloads/en/DeviceDoc/20002190C.pdfI would like to place PCB heat sink below MCP73213 IC to allow power dissipation. What should be the dimension of PCB heat sink. I am really confused. Please help me in this regard.

author: danadak
author_rank: Super Contributor
timestamp: September 13, 2017, 11:47:04 am
content: These might help -http://www.ti.com/lit/an/snva183b/snva183b.pdfhttp://www.ti.com/lit/an/snva419c/snva419c.pdfhttps://www.nxp.com/downloads/en/thermal-model/IC26_CHAPTER_6.pdfAnd Webbench, a sim and design tool, free, online -http://www.ti.com/design-tools/overview.html?keyMatch=webbench&tisearch=Search-EN-Everything&rec=trueRegards, Dana.
How to decide maximum input current required in linear charging method? - Page 1
Forum section: electronics / projects

author: Sai teja
author_rank: Regular Contributor
timestamp: September 13, 2017, 07:16:21 am
content: I am using MCP73213 IC for my charging application. I would like to use the maximum capacity of the IC for charging. i.e., 1 ampere charge current during constant current charge cycle. What the maximum input current required for this application. I want to use 9 volt adapter as input. Please help me in this regard.Thankyou.

author: sleemanj
author_rank: Super Contributor
timestamp: September 13, 2017, 07:46:32 am
content: Read page 18 of the datasheet

author: Sai teja
author_rank: Regular Contributor
timestamp: September 13, 2017, 08:36:22 am
content: According to my knowledge Ireg(which is mentioned in page 18 of datasheet) is the current from charging IC to battery.Is it same as input source current?I would like to know amount of maximum source current required from power adapter.

author: sleemanj
author_rank: Super Contributor
timestamp: September 13, 2017, 09:29:35 am
content: The input current will be very close to the output current (should be about 2ma higher for the IC to run itself, plus LED current depending on the resistor you use).
how to demodulate signal using xr2211 ic for low freq 180hz and 340hz - Page 1
Forum section: electronics / projects

author: Kheshav
author_rank: Newbie
timestamp: December 17, 2023, 12:29:50 pm
content: i m trying to do fsk demodulation using xr2211 ic for f1=180hz and f2=340hz and baudrate of 206i using this datasheethttps://assets.maxlinear.com/web/documents/xr2211av104.pdfand my values areR0=39k + 10k(pot)C0=0.1ufR1= 100kC1=5.6nfRf=510kCf=2.2nfRb=2.2MRL=5.1ki m not getting proper fsk data at pin 7can anyone tell me what i am doing wrongthis my circuit diagram

author: Terry Bites
author_rank: Super Contributor
timestamp: December 17, 2023, 01:42:20 pm
content: With the components shown, your centre frequency is only 41Hz. It needs to be centred between the upper and lower fsk frequencies. More like 250Hz so Co~15n.
How to derate PWM current measurement? - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: April 27, 2019, 09:18:56 pm
content: If I know the duty cycle of the pure pulsed DC voltage, and my AC/DC RMS clamp meter tells me it sees 20 amps, is there a direct relationship between duty cycle and true current I can use to know the real current? (Frequency is unknown but this shouldn't be a factor as long as it is within the specifications of the meter.)For example, I know that for 50 percent duty cycle it's common knowledge that real current is 10 percent above measured. Likewise, is there a known relationship for other duty cycles?It is inconvenient to measure "directly" using a shunt, so a clamp meter is my only option right now.Thanks.
How to design a basic mains switch-mode converter? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: December 23, 2017, 04:16:12 pm
content: Like those el-cheapo phone chargers, but with proper isolation and protection. How can I do this? I am still a bit intimidated by winding my own transformer.

author: prasimix
author_rank: Unknown
timestamp: December 23, 2017, 05:39:11 pm
content: Select then one of already available transformer. I found one in Poland, Feryster, andhereis my first eval. board based TNY266 and their TI-EE16-1534. If you have different requirements, check Feryster'stransformer list.Other possibility is Myrra transforms available thruFarnell, e.g. model 74000, 74001, 74002, 74003, 74010, etc. or perhaps Hahn available thruTME.If you are in China it is easy to imagine another myriad manufacturers of ready made flyback transformers.

author: fourtytwo42
author_rank: Super Contributor
timestamp: December 23, 2017, 05:43:52 pm
content: Quote from: prasimix on December 23, 2017, 05:39:11 pmUnfortunately I think that is exactly the problem the OP has, an awful lot of Chinese transformers DO NOT meet safety standards! Buy from a reputable European/American sourceI should add to this that if you are considering winding your own transformer please ensure you are familiar with the internal construction methods required to meet safety standards first, your life may depend upon it!

author: Phoenix
author_rank: Frequent Contributor
timestamp: December 24, 2017, 12:08:12 am
content: Check out Power integrations PI expert design tool. It designes the whole circuit including transformer core and windings. Will be simple but not the cheapest solution.Sent from my G8441 using Tapatalk

author: ebclr
author_rank: Super Contributor
timestamp: December 24, 2017, 12:16:15 am
content: "reputable European/American source"Who is a China reseller......

author: janekm
author_rank: Unknown
timestamp: December 24, 2017, 07:32:27 am
content: Quote from: blueskull on December 24, 2017, 12:44:40 amBoth true, though unfortunately I found that at least some of the e-waste reusers (In principle a good thing both for the environment and safety) re-box the power supply PCBs (Delta is popular, as is Emerson or one of their sub-brands, both as reputable as it gets), together with a newly-printed label complete with lots of typos. Which makes it a bit less useful for re-importing into western countries...I've also ordered from the Shanghai Meanwell distributor

author: jaycee
author_rank: Regular Contributor
timestamp: December 24, 2017, 11:29:50 am
content: Myrra make some off-the-shelf transformers for use in off-line SMPS circuitshttp://myrra.com/flyback/Ultimately though, don't try to wind your own unless you already have experience. Just one small failure in insulation and you have a live secondary == destruction of the load, and probably you as well.

author: Ice-Tea
author_rank: Super Contributor
timestamp: December 24, 2017, 11:42:16 am
content: If you end up doing it yourself for some reason: I second the PI suggestion. Perfect for starters.